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Exhibit A
Proposed Reliability Standard TPL-007-2 – Transmission System Planned Performance for
Geomagnetic Disturbance Operations
Proposed Reliability Standard TPL-007-2 – Transmission System Planned Performance for
Geomagnetic Disturbance Operations - Clean
TPL‐007‐2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
A. Introduction
1.
Title:
Events
Transmission System Planned Performance for Geomagnetic Disturbance
2.
Number:
TPL‐007‐2
3.
Purpose: Establish requirements for Transmission system planned performance
during geomagnetic disturbance (GMD) events.
4.
Applicability:
4.1. Functional Entities:
4.1.1. Planning Coordinator with a planning area that includes a Facility or
Facilities specified in 4.2;
4.1.2. Transmission Planner with a planning area that includes a Facility or
Facilities specified in 4.2;
4.1.3. Transmission Owner who owns a Facility or Facilities specified in 4.2; and
4.1.4. Generator Owner who owns a Facility or Facilities specified in 4.2.
4.2. Facilities:
4.2.1. Facilities that include power transformer(s) with a high side, wye‐
grounded winding with terminal voltage greater than 200 kV.
5.
Effective Date: See Implementation Plan for TPL‐007‐2.
6.
Background: During a GMD event, geomagnetically‐induced currents (GIC) may cause
transformer hot‐spot heating or damage, loss of Reactive Power sources, increased
Reactive Power demand, and Misoperation(s), the combination of which may result in
voltage collapse and blackout
B. Requirements and Measures
R1. Each Planning Coordinator, in conjunction with its Transmission Planner(s), shall
identify the individual and joint responsibilities of the Planning Coordinator and
Transmission Planner(s) in the Planning Coordinator’s planning area for maintaining
models, performing the study or studies needed to complete benchmark and
supplemental GMD Vulnerability Assessments, and implementing process(es) to
obtain GMD measurement data as specified in this standard. [Violation Risk Factor:
Lower] [Time Horizon: Long‐term Planning]
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TPL‐007‐2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
M1. Each Planning Coordinator, in conjunction with its Transmission Planners, shall provide
documentation on roles and responsibilities, such as meeting minutes, agreements,
copies of procedures or protocols in effect between entities or between departments
of a vertically integrated system, or email correspondence that identifies an
agreement has been reached on individual and joint responsibilities for maintaining
models, performing the study or studies needed to complete benchmark and
supplemental GMD Vulnerability Assessments, and implementing process(es) to
obtain GMD measurement data in accordance with Requirement R1.
R2. Each responsible entity, as determined in Requirement R1, shall maintain System
models and GIC System models of the responsible entity’s planning area for
performing the study or studies needed to complete benchmark and supplemental
GMD Vulnerability Assessments. [Violation Risk Factor: High] [Time Horizon: Long‐
term Planning]
M2. Each responsible entity, as determined in Requirement R1, shall have evidence in
either electronic or hard copy format that it is maintaining System models and GIC
System models of the responsible entity’s planning area for performing the study or
studies needed to complete benchmark and supplemental GMD Vulnerability
Assessments.
R3. Each responsible entity, as determined in Requirement R1, shall have criteria for
acceptable System steady state voltage performance for its System during the GMD
events described in Attachment 1. [Violation Risk Factor: Medium] [Time Horizon:
Long‐term Planning]
M3. Each responsible entity, as determined in Requirement R1, shall have evidence, such
as electronic or hard copies of the criteria for acceptable System steady state voltage
performance for its System in accordance with Requirement R3.
Benchmark GMD Vulnerability Assessment(s)
R4. Each responsible entity, as determined in Requirement R1, shall complete a
benchmark GMD Vulnerability Assessment of the Near‐Term Transmission Planning
Horizon at least once every 60 calendar months. This benchmark GMD Vulnerability
Assessment shall use a study or studies based on models identified in Requirement R2,
document assumptions, and document summarized results of the steady state
analysis. [Violation Risk Factor: High] [Time Horizon: Long‐term Planning]
4.1. The study or studies shall include the following conditions:
4.1.1. System On‐Peak Load for at least one year within the Near‐Term
Transmission Planning Horizon; and
4.1.2. System Off‐Peak Load for at least one year within the Near‐Term
Transmission Planning Horizon.
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TPL‐007‐2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
4.2. The study or studies shall be conducted based on the benchmark GMD event
described in Attachment 1 to determine whether the System meets the
performance requirements for the steady state planning benchmark GMD event
contained in Table 1.
4.3. The benchmark GMD Vulnerability Assessment shall be provided: (i) to the
responsible entity’s Reliability Coordinator, adjacent Planning Coordinators, and
adjacent Transmission Planners within 90 calendar days of completion, and (ii) to
any functional entity that submits a written request and has a reliability‐related
need within 90 calendar days of receipt of such request or within 90 calendar
days of completion of the benchmark GMD Vulnerability Assessment, whichever
is later.
4.3.1. If a recipient of the benchmark GMD Vulnerability Assessment provides
documented comments on the results, the responsible entity shall
provide a documented response to that recipient within 90 calendar days
of receipt of those comments.
M4. Each responsible entity, as determined in Requirement R1, shall have dated evidence
such as electronic or hard copies of its benchmark GMD Vulnerability Assessment
meeting all of the requirements in Requirement R4. Each responsible entity, as
determined in Requirement R1, shall also provide evidence, such as email records,
web postings with an electronic notice of posting, or postal receipts showing recipient
and date, that it has distributed its benchmark GMD Vulnerability Assessment: (i) to
the responsible entity’s Reliability Coordinator, adjacent Planning Coordinators, and
adjacent Transmission Planners within 90 calendar days of completion, and (ii) to any
functional entity that submits a written request and has a reliability‐related need
within 90 calendar days of receipt of such request or within 90 calendar days of
completion of the benchmark GMD Vulnerability Assessment, whichever is later, as
specified in Requirement R4. Each responsible entity, as determined in Requirement
R1, shall also provide evidence, such as email notices or postal receipts showing
recipient and date, that it has provided a documented response to comments received
on its benchmark GMD Vulnerability Assessment within 90 calendar days of receipt of
those comments in accordance with Requirement R4.
R5. Each responsible entity, as determined in Requirement R1, shall provide GIC flow
information to be used for the benchmark thermal impact assessment of transformers
specified in Requirement R6 to each Transmission Owner and Generator Owner that
owns an applicable Bulk Electric System (BES) power transformer in the planning area.
The GIC flow information shall include: [Violation Risk Factor: Medium] [Time Horizon:
Long‐term Planning]
5.1. The maximum effective GIC value for the worst case geoelectric field orientation
for the benchmark GMD event described in Attachment 1. This value shall be
provided to the Transmission Owner or Generator Owner that owns each
applicable BES power transformer in the planning area.
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TPL‐007‐2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
5.2. The effective GIC time series, GIC(t), calculated using the benchmark GMD event
described in Attachment 1 in response to a written request from the
Transmission Owner or Generator Owner that owns an applicable BES power
transformer in the planning area. GIC(t) shall be provided within 90 calendar
days of receipt of the written request and after determination of the maximum
effective GIC value in Part 5.1.
M5. Each responsible entity, as determined in Requirement R1, shall provide evidence,
such as email records, web postings with an electronic notice of posting, or postal
receipts showing recipient and date, that it has provided the maximum effective GIC
values to the Transmission Owner and Generator Owner that owns each applicable
BES power transformer in the planning area as specified in Requirement R5, Part 5.1.
Each responsible entity, as determined in Requirement R1, shall also provide evidence,
such as email records, web postings with an electronic notice of posting, or postal
receipts showing recipient and date, that it has provided GIC(t) in response to a
written request from the Transmission Owner or Generator Owner that owns an
applicable BES power transformer in the planning area.
R6. Each Transmission Owner and Generator Owner shall conduct a benchmark thermal
impact assessment for its solely and jointly owned applicable BES power transformers
where the maximum effective GIC value provided in Requirement R5, Part 5.1, is 75 A
per phase or greater. The benchmark thermal impact assessment shall: [Violation Risk
Factor: Medium] [Time Horizon: Long‐term Planning]
6.1. Be based on the effective GIC flow information provided in Requirement R5;
6.2. Document assumptions used in the analysis;
6.3. Describe suggested actions and supporting analysis to mitigate the impact of
GICs, if any; and
6.4. Be performed and provided to the responsible entities, as determined in
Requirement R1, within 24 calendar months of receiving GIC flow information
specified in Requirement R5, Part 5.1.
M6. Each Transmission Owner and Generator Owner shall have evidence such as electronic
or hard copies of its benchmark thermal impact assessment for all of its solely and
jointly owned applicable BES power transformers where the maximum effective GIC
value provided in Requirement R5, Part 5.1, is 75 A per phase or greater, and shall
have evidence such as email records, web postings with an electronic notice of
posting, or postal receipts showing recipient and date, that it has provided its thermal
impact assessment to the responsible entities as specified in Requirement R6.
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TPL‐007‐2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
R7. Each responsible entity, as determined in Requirement R1, that concludes through the
benchmark GMD Vulnerability Assessment conducted in Requirement R4 that their
System does not meet the performance requirements for the steady state planning
benchmark GMD event contained in Table 1, shall develop a Corrective Action Plan
(CAP) addressing how the performance requirements will be met. The CAP shall:
[Violation Risk Factor: High] [Time Horizon: Long‐term Planning]
7.1. List System deficiencies and the associated actions needed to achieve required
System performance. Examples of such actions include:
Installation, modification, retirement, or removal of Transmission and
generation Facilities and any associated equipment.
Installation, modification, or removal of Protection Systems or Remedial
Action Schemes.
Use of Operating Procedures, specifying how long they will be needed as
part of the CAP.
Use of Demand‐Side Management, new technologies, or other initiatives.
7.2. Be developed within one year of completion of the benchmark GMD
Vulnerability Assessment.
7.3. Include a timetable, subject to revision by the responsible entity in Part 7.4, for
implementing the selected actions from Part 7.1. The timetable shall:
7.3.1. Specify implementation of non‐hardware mitigation, if any, within two
years of development of the CAP; and
7.3.2. Specify implementation of hardware mitigation, if any, within four years
of development of the CAP.
7.4. Be revised if situations beyond the control of the responsible entity determined
in Requirement R1 prevent implementation of the CAP within the timetable for
implementation provided in Part 7.3. The revised CAP shall document the
following, and be updated at least once every 12 calendar months until
implemented:
7.4.1. Circumstances causing the delay for fully or partially implementing the
selected actions in Part 7.1;
7.4.2. Description of the original CAP, and any previous changes to the CAP,
with the associated timetable(s) for implementing the selected actions in
Part 7.1; and
7.4.3. Revisions to the selected actions in Part 7.1, if any, including utilization of
Operating Procedures if applicable, and the updated timetable for
implementing the selected actions.
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TPL‐007‐2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
7.5. Be provided: (i) to the responsible entity’s Reliability Coordinator, adjacent
Planning Coordinator(s), adjacent Transmission Planner(s), and functional
entities referenced in the CAP within 90 calendar days of development or
revision, and (ii) to any functional entity that submits a written request and has a
reliability‐related need within 90 calendar days of receipt of such request or
within 90 calendar days of development or revision, whichever is later.
7.5.1. If a recipient of the CAP provides documented comments on the results,
the responsible entity shall provide a documented response to that
recipient within 90 calendar days of receipt of those comments.
M7. Each responsible entity, as determined in Requirement R1, that concludes, through
the benchmark GMD Vulnerability Assessment conducted in Requirement R4, that the
responsible entity’s System does not meet the performance requirements for the
steady state planning benchmark GMD event contained in Table 1 shall have evidence
such as dated electronic or hard copies of its CAP including timetable for
implementing selected actions, as specified in Requirement R7. Each responsible
entity, as determined in Requirement R1, shall also provide evidence, such as email
records or postal receipts showing recipient and date, that it has revised its CAP if
situations beyond the responsible entity's control prevent implementation of the CAP
within the timetable specified. Each responsible entity, as determined in Requirement
R1, shall also provide evidence, such as email records, web postings with an electronic
notice of posting, or postal receipts showing recipient and date, that it has distributed
its CAP or relevant information, if any, (i) to the responsible entity’s Reliability
Coordinator, adjacent Planning Coordinator(s), adjacent Transmission Planner(s), and
functional entities referenced in the CAP within 90 calendar days of development or
revision, and (ii) to any functional entity that submits a written request and has a
reliability‐related need within 90 calendar days of receipt of such request or within 90
calendar days of development or revision, whichever is later as specified in
Requirement R7. Each responsible entity, as determined in Requirement R1, shall also
provide evidence, such as email notices or postal receipts showing recipient and date,
that it has provided a documented response to comments received on its CAP within
90 calendar days of receipt of those comments, in accordance with Requirement R7.
Supplemental GMD Vulnerability Assessment(s)
R8.
Each responsible entity, as determined in Requirement R1, shall complete a
supplemental GMD Vulnerability Assessment of the Near‐Term Transmission Planning
Horizon at least once every 60 calendar months. This supplemental GMD Vulnerability
Assessment shall use a study or studies based on models identified in Requirement
R2, document assumptions, and document summarized results of the steady state
analysis. [Violation Risk Factor: High] [Time Horizon: Long‐term Planning]
8.1. The study or studies shall include the following conditions:
8.1.1. System On‐Peak Load for at least one year within the Near‐Term
Transmission Planning Horizon; and
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TPL‐007‐2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
8.1.2. System Off‐Peak Load for at least one year within the Near‐Term
Transmission Planning Horizon.
8.2. The study or studies shall be conducted based on the supplemental GMD event
described in Attachment 1 to determine whether the System meets the
performance requirements for the steady state planning supplemental GMD
event contained in Table 1.
8.3. If the analysis concludes there is Cascading caused by the supplemental GMD
event described in Attachment 1, an evaluation of possible actions designed to
reduce the likelihood or mitigate the consequences and adverse impacts of the
event(s) shall be conducted.
8.4. The supplemental GMD Vulnerability Assessment shall be provided: (i) to the
responsible entity’s Reliability Coordinator, adjacent Planning Coordinators,
adjacent Transmission Planners within 90 calendar days of completion, and (ii) to
any functional entity that submits a written request and has a reliability‐related
need within 90 calendar days of receipt of such request or within 90 calendar
days of completion of the supplemental GMD Vulnerability Assessment,
whichever is later.
8.4.1. If a recipient of the supplemental GMD Vulnerability Assessment
provides documented comments on the results, the responsible entity
shall provide a documented response to that recipient within 90 calendar
days of receipt of those comments.
M8. Each responsible entity, as determined in Requirement R1, shall have dated evidence
such as electronic or hard copies of its supplemental GMD Vulnerability Assessment
meeting all of the requirements in Requirement R8. Each responsible entity, as
determined in Requirement R1, shall also provide evidence, such as email records,
web postings with an electronic notice of posting, or postal receipts showing recipient
and date, that it has distributed its supplemental GMD Vulnerability: (i) to the
responsible entity’s Reliability Coordinator, adjacent Planning Coordinators, adjacent
Transmission Planners within 90 calendar days of completion, and (ii) to any
functional entity that submits a written request and has a reliability‐related need
within 90 calendar days of receipt of such request or within 90 calendar days of
completion of the supplemental GMD Vulnerability Assessment, whichever is later, as
specified in Requirement R8. Each responsible entity, as determined in Requirement
R1, shall also provide evidence, such as email notices or postal receipts showing
recipient and date, that it has provided a documented response to comments
received on its supplemental GMD Vulnerability Assessment within 90 calendar days
of receipt of those comments in accordance with Requirement R8.
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TPL‐007‐2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
R9.
Each responsible entity, as determined in Requirement R1, shall provide GIC flow
information to be used for the supplemental thermal impact assessment of
transformers specified in Requirement R10 to each Transmission Owner and
Generator Owner that owns an applicable Bulk Electric System (BES) power
transformer in the planning area. The GIC flow information shall include: [Violation
Risk Factor: Medium] [Time Horizon: Long‐term Planning]
9.1. The maximum effective GIC value for the worst case geoelectric field orientation
for the supplemental GMD event described in Attachment 1. This value shall be
provided to the Transmission Owner or Generator Owner that owns each
applicable BES power transformer in the planning area.
9.2. The effective GIC time series, GIC(t), calculated using the supplemental GMD
event described in Attachment 1 in response to a written request from the
Transmission Owner or Generator Owner that owns an applicable BES power
transformer in the planning area. GIC(t) shall be provided within 90 calendar
days of receipt of the written request and after determination of the maximum
effective GIC value in Part 9.1.
M9. Each responsible entity, as determined in Requirement R1, shall provide evidence,
such as email records, web postings with an electronic notice of posting, or postal
receipts showing recipient and date, that it has provided the maximum effective GIC
values to the Transmission Owner and Generator Owner that owns each applicable
BES power transformer in the planning area as specified in Requirement R9, Part 9.1.
Each responsible entity, as determined in Requirement R1, shall also provide
evidence, such as email records, web postings with an electronic notice of posting, or
postal receipts showing recipient and date, that it has provided GIC(t) in response to a
written request from the Transmission Owner or Generator Owner that owns an
applicable BES power transformer in the planning area.
R10. Each Transmission Owner and Generator Owner shall conduct a supplemental
thermal impact assessment for its solely and jointly owned applicable BES power
transformers where the maximum effective GIC value provided in Requirement R9,
Part 9.1, is 85 A per phase or greater. The supplemental thermal impact assessment
shall: [Violation Risk Factor: Medium] [Time Horizon: Long‐term Planning]
10.1. Be based on the effective GIC flow information provided in Requirement R9;
10.2. Document assumptions used in the analysis;
10.3. Describe suggested actions and supporting analysis to mitigate the impact of
GICs, if any; and
10.4. Be performed and provided to the responsible entities, as determined in
Requirement R1, within 24 calendar months of receiving GIC flow information
specified in Requirement R9, Part 9.1.
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TPL‐007‐2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
M10. Each Transmission Owner and Generator Owner shall have evidence such as
electronic or hard copies of its supplemental thermal impact assessment for all of its
solely and jointly owned applicable BES power transformers where the maximum
effective GIC value provided in Requirement R9, Part 9.1, is 85 A per phase or greater,
and shall have evidence such as email records, web postings with an electronic notice
of posting, or postal receipts showing recipient and date, that it has provided its
supplemental thermal impact assessment to the responsible entities as specified in
Requirement R10.
GMD Measurement Data Processes
R11. Each responsible entity, as determined in Requirement R1, shall implement a process
to obtain GIC monitor data from at least one GIC monitor located in the Planning
Coordinator's planning area or other part of the system included in the Planning
Coordinator's GIC System model. [Violation Risk Factor: Lower] [Time Horizon: Long‐
term Planning]
M11. Each responsible entity, as determined in Requirement R1, shall have evidence such
as electronic or hard copies of its GIC monitor location(s) and documentation of its
process to obtain GIC monitor data in accordance with Requirement R11.
R12. Each responsible entity, as determined in Requirement R1, shall implement a process
to obtain geomagnetic field data for its Planning Coordinator’s planning area.
[Violation Risk Factor: Lower] [Time Horizon: Long‐term Planning]
M12. Each responsible entity, as determined in Requirement R1, shall have evidence such
as electronic or hard copies of its process to obtain geomagnetic field data for its
Planning Coordinator’s planning area in accordance with Requirement R12.
C. Compliance
1.
Compliance Monitoring Process
1.1. Compliance Enforcement Authority: “Compliance Enforcement Authority”
means NERC or the Regional Entity, or any entity as otherwise designated by an
Applicable Governmental Authority, in their respective roles of monitoring
and/or enforcing compliance with mandatory and enforceable Reliability
Standards in their respective jurisdictions.
1.2. Evidence Retention: The following evidence retention period(s) identify the
period of time an entity is required to retain specific evidence to demonstrate
compliance. For instances where the evidence retention period specified below
is shorter than the time since the last audit, the Compliance Enforcement
Authority may ask an entity to provide other evidence to show that it was
compliant for the full‐time period since the last audit.
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TPL‐007‐2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
The applicable entity shall keep data or evidence to show compliance as
identified below unless directed by its Compliance Enforcement Authority to
retain specific evidence for a longer period of time as part of an investigation.
For Requirements R1, R2, R3, R5, R6, R9, and R10, each responsible entity
shall retain documentation as evidence for five years.
For Requirements R4 and R8, each responsible entity shall retain
documentation of the current GMD Vulnerability Assessment and the
preceding GMD Vulnerability Assessment.
For Requirement R7, each responsible entity shall retain documentation as
evidence for five years or until all actions in the Corrective Action Plan are
completed, whichever is later.
For Requirements R11 and R12, each responsible entity shall retain
documentation as evidence for three years.
1.3. Compliance Monitoring and Enforcement Program: As defined in the NERC
Rules of Procedure, “Compliance Monitoring and Enforcement Program” refers
to the identification of the processes that will be used to evaluate data or
information for the purpose of assessing performance or outcomes with the
associated Reliability Standard.
Page 10 of 40
TPL‐007‐2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
Table 1: Steady State Planning GMD Event
Steady State:
a. Voltage collapse, Cascading and uncontrolled islanding shall not occur.
b. Generation loss is acceptable as a consequence of the steady state planning GMD events.
c. Planned System adjustments such as Transmission configuration changes and re‐dispatch of generation are allowed if such
adjustments are executable within the time duration applicable to the Facility Ratings.
Category
Initial Condition
Event
Interruption of
Firm
Transmission
Service Allowed
Load Loss
Allowed
1. System as may be
Benchmark GMD
postured in response
Event ‐ GMD Event to space weather
with Outages
information1, and then
2. GMD event2
Reactive Power compensation devices
and other Transmission Facilities
removed as a result of Protection
System operation or Misoperation due
to harmonics during the GMD event
Yes3
Yes3
1. System as may be
postured in response
to space weather
information1, and then
2. GMD event2
Reactive Power compensation devices
and other Transmission Facilities
removed as a result of Protection
System operation or Misoperation due
to harmonics during the GMD event
Yes
Yes
Supplemental
GMD Event ‐ GMD
Event with
Outages
Table 1: Steady State Performance Footnotes
1. The System condition for GMD planning may include adjustments to posture the System that are executable in response to
space weather information.
2. The GMD conditions for the benchmark and supplemental planning events are described in Attachment 1.
3. Load loss as a result of manual or automatic Load shedding (e.g., UVLS) and/or curtailment of Firm Transmission Service may
be used to meet BES performance requirements during studied GMD conditions. The likelihood and magnitude of Load loss or
curtailment of Firm Transmission Service should be minimized.
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TPL‐007‐2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
Violation Severity Levels
R#
R1.
R2.
Violation Severity Levels
Lower VSL
N/A
N/A
Moderate VSL
N/A
N/A
High VSL
Severe VSL
N/A
The Planning Coordinator, in
conjunction with its
Transmission Planner(s),
failed to determine and
identify individual or joint
responsibilities of the
Planning Coordinator and
Transmission Planner(s) in
the Planning Coordinator’s
planning area for
maintaining models,
performing the study or
studies needed to complete
benchmark and
supplemental GMD
Vulnerability Assessments,
and implementing
process(es) to obtain GMD
measurement data as
specified in this standard.
The responsible entity did
not maintain either System
models or GIC System
models of the responsible
entity’s planning area for
performing the studies
The responsible entity did
not maintain both System
models and GIC System
models of the responsible
entity’s planning area for
performing the studies
Page 12 of 40
TPL‐007‐2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
R#
Violation Severity Levels
Lower VSL
Moderate VSL
High VSL
needed to complete
benchmark and
supplemental GMD
Vulnerability Assessments.
R3.
R4.
N/A
N/A
N/A
The responsible entity
completed a benchmark
GMD Vulnerability
Assessment, but it was more
than 60 calendar months
and less than or equal to 64
calendar months since the
last benchmark GMD
Vulnerability Assessment.
The responsible entity's
completed benchmark GMD
Vulnerability Assessment
failed to satisfy one of the
elements listed in
Requirement R4, Parts 4.1
through 4.3;
OR
The responsible entity
completed a benchmark
GMD Vulnerability
Assessment, but it was more
than 64 calendar months
and less than or equal to 68
calendar months since the
The responsible entity's
completed benchmark GMD
Vulnerability Assessment
failed to satisfy two of the
elements listed in
Requirement R4, Parts 4.1
through 4.3;
OR
The responsible entity
completed a benchmark
GMD Vulnerability
Assessment, but it was more
than 68 calendar months
and less than or equal to 72
calendar months since the
Severe VSL
needed to complete
benchmark and
supplemental GMD
Vulnerability Assessments.
The responsible entity did
not have criteria for
acceptable System steady
state voltage performance
for its System during the
GMD events described in
Attachment 1 as required.
The responsible entity's
completed benchmark GMD
Vulnerability Assessment
failed to satisfy three of the
elements listed in
Requirement R4, Parts 4.1
through 4.3;
OR
The responsible entity
completed a benchmark
GMD Vulnerability
Assessment, but it was more
than 72 calendar months
since the last benchmark
Page 13 of 40
TPL‐007‐2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
R#
R5.
R6.
Violation Severity Levels
Lower VSL
Moderate VSL
High VSL
Severe VSL
last benchmark GMD
Vulnerability Assessment.
last benchmark GMD
Vulnerability Assessment.
GMD Vulnerability
Assessment;
OR
The responsible entity does
not have a completed
benchmark GMD
Vulnerability Assessment.
The responsible entity
provided the effective GIC
time series, GIC(t), in
response to written request,
but did so more than 90
calendar days and less than
or equal to 100 calendar
days after receipt of a
written request.
The responsible entity
provided the effective GIC
time series, GIC(t), in
response to written request,
but did so more than 100
calendar days and less than
or equal to 110 calendar
days after receipt of a
written request.
The responsible entity
provided the effective GIC
time series, GIC(t), in
response to written request,
but did so more than 110
calendar days after receipt
of a written request.
The responsible entity did
not provide the maximum
effective GIC value to the
Transmission Owner and
Generator Owner that owns
each applicable BES power
transformer in the planning
area;
OR
The responsible entity did
not provide the effective GIC
time series, GIC(t), upon
written request.
The responsible entity failed
to conduct a benchmark
thermal impact assessment
for 5% or less or one of its
solely owned and jointly
owned applicable BES power
The responsible entity failed
to conduct a benchmark
thermal impact assessment
for more than 5% up to (and
including) 10% or two of its
solely owned and jointly
The responsible entity failed
to conduct a benchmark
thermal impact assessment
for more than 10% up to
(and including) 15% or three
of its solely owned and
The responsible entity failed
to conduct a benchmark
thermal impact assessment
for more than 15% or more
than three of its solely
owned and jointly owned
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TPL‐007‐2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
R#
Violation Severity Levels
Lower VSL
Moderate VSL
High VSL
Severe VSL
transformers (whichever is
greater) where the
maximum effective GIC
value provided in
Requirement R5, Part 5.1, is
75 A or greater per phase;
OR
The responsible entity
conducted a benchmark
thermal impact assessment
for its solely owned and
jointly owned applicable BES
power transformers where
the maximum effective GIC
value provided in
Requirement R5, Part 5.1, is
75 A or greater per phase
but did so more than 24
calendar months and less
than or equal to 26 calendar
months of receiving GIC flow
information specified in
Requirement R5, Part 5.1.
owned applicable BES power
transformers (whichever is
greater) where the
maximum effective GIC
value provided in
Requirement R5, Part 5.1, is
75 A or greater per phase;
OR
The responsible entity
conducted a benchmark
thermal impact assessment
for its solely owned and
jointly owned applicable BES
power transformers where
the maximum effective GIC
value provided in
Requirement R5, Part 5.1, is
75 A or greater per phase
but did so more than 26
calendar months and less
than or equal to 28 calendar
months of receiving GIC flow
information specified in
Requirement R5, Part 5.1;
OR
The responsible entity failed
to include one of the
jointly owned applicable BES
power transformers
(whichever is greater) where
the maximum effective GIC
value provided in
Requirement R5, Part 5.1, is
75 A or greater per phase;
OR
The responsible entity
conducted a benchmark
thermal impact assessment
for its solely owned and
jointly owned applicable BES
power transformers where
the maximum effective GIC
value provided in
Requirement R5, Part 5.1, is
75 A or greater per phase
but did so more than 28
calendar months and less
than or equal to 30 calendar
months of receiving GIC flow
information specified in
Requirement R5, Part 5.1;
OR
The responsible entity failed
to include two of the
applicable BES power
transformers (whichever is
greater) where the
maximum effective GIC
value provided in
Requirement R5, Part 5.1, is
75 A or greater per phase;
OR
The responsible entity
conducted a benchmark
thermal impact assessment
for its solely owned and
jointly owned applicable BES
power transformers where
the maximum effective GIC
value provided in
Requirement R5, Part 5.1, is
75 A or greater per phase
but did so more than 30
calendar months of receiving
GIC flow information
specified in Requirement R5,
Part 5.1;
OR
The responsible entity failed
to include three of the
required elements as listed
Page 15 of 40
TPL‐007‐2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
R#
Violation Severity Levels
Lower VSL
Moderate VSL
High VSL
Severe VSL
required elements as listed
required elements as listed
in Requirement R6, Parts 6.1
in Requirement R6, Parts 6.1 in Requirement R6, Parts 6.1 through 6.3.
through 6.3.
through 6.3.
The responsible entity's
Corrective Action Plan failed
to comply with one of the
elements in Requirement
R7, Parts 7.1 through 7.5.
The responsible entity's
Corrective Action Plan failed
to comply with two of the
elements in Requirement R7,
Parts 7.1 through 7.5.
The responsible entity's
Corrective Action Plan failed
to comply with three of the
elements in Requirement
R7, Parts 7.1 through 7.5.
The responsible entity's
Corrective Action Plan failed
to comply with four or more
of the elements in
Requirement R7, Parts 7.1
through 7.5;
OR
The responsible entity did
not have a Corrective Action
Plan as required by
Requirement R7.
The responsible entity's
completed supplemental
GMD Vulnerability
Assessment failed to satisfy
one of elements listed in
Requirement R8, Parts 8.1
through 8.4;
OR
The responsible entity
completed a supplemental
GMD Vulnerability
Assessment, but it was more
The responsible entity's
completed supplemental
GMD Vulnerability
Assessment failed to satisfy
two of elements listed in
Requirement R8, Parts 8.1
through 8.4;
OR
The responsible entity
completed a supplemental
GMD Vulnerability
Assessment, but it was more
The responsible entity's
completed supplemental
GMD Vulnerability
Assessment failed to satisfy
three of the elements listed
in Requirement R8, Parts 8.1
through 8.4;
OR
The responsible entity
completed a supplemental
GMD Vulnerability
Assessment, but it was more
The responsible entity's
completed supplemental
GMD Vulnerability
Assessment failed to satisfy
four of the elements listed in
Requirement R8, Parts 8.1
through 8.4;
OR
The responsible entity
completed a supplemental
GMD Vulnerability
Assessment, but it was more
R7.
R8.
Page 16 of 40
TPL‐007‐2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
R#
R9.
R10.
Violation Severity Levels
Lower VSL
Moderate VSL
High VSL
Severe VSL
than 60 calendar months
and less than or equal to 64
calendar months since the
last supplemental GMD
Vulnerability Assessment.
than 64 calendar months
and less than or equal to 68
calendar months since the
last supplemental GMD
Vulnerability Assessment.
than 68 calendar months
and less than or equal to 72
calendar months since the
last supplemental GMD
Vulnerability Assessment.
than 72 calendar months
since the last supplemental
GMD Vulnerability
Assessment;
OR
The responsible entity does
not have a completed
supplemental GMD
Vulnerability Assessment.
The responsible entity
provided the effective GIC
time series, GIC(t), in
response to written request,
but did so more than 90
calendar days and less than
or equal to 100 calendar
days after receipt of a
written request.
The responsible entity
provided the effective GIC
time series, GIC(t), in
response to written request,
but did so more than 100
calendar days and less than
or equal to 110 calendar
days after receipt of a
written request.
The responsible entity
provided the effective GIC
time series, GIC(t), in
response to written request,
but did so more than 110
calendar days after receipt
of a written request.
The responsible entity did
not provide the maximum
effective GIC value to the
Transmission Owner and
Generator Owner that owns
each applicable BES power
transformer in the planning
area;
OR
The responsible entity did
not provide the effective GIC
time series, GIC(t), upon
written request.
The responsible entity failed
to conduct a supplemental
thermal impact assessment
for 5% or less or one of its
The responsible entity failed
to conduct a supplemental
thermal impact assessment
for more than 5% up to (and
The responsible entity failed
to conduct a supplemental
thermal impact assessment
for more than 10% up to
The responsible entity failed
to conduct a supplemental
thermal impact assessment
for more than 15% or more
Page 17 of 40
TPL‐007‐2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
R#
Violation Severity Levels
Lower VSL
Moderate VSL
High VSL
Severe VSL
solely owned and jointly
owned applicable BES power
transformers (whichever is
greater) where the
maximum effective GIC
value provided in
Requirement R9, Part 9.1, is
85 A or greater per phase;
OR
The responsible entity
conducted a supplemental
thermal impact assessment
for its solely owned and
jointly owned applicable BES
power transformers where
the maximum effective GIC
value provided in
Requirement R9, Part 9.1, is
85 A or greater per phase
but did so more than 24
calendar months and less
than or equal to 26 calendar
months of receiving GIC flow
information specified in
Requirement R9, Part 9.1.
including) 10% or two of its
solely owned and jointly
owned applicable BES power
transformers (whichever is
greater) where the
maximum effective GIC
value provided in
Requirement R9, Part 9.1, is
85 A or greater per phase;
OR
The responsible entity
conducted a supplemental
thermal impact assessment
for its solely owned and
jointly owned applicable BES
power transformers where
the maximum effective GIC
value provided in
Requirement R9, Part 9.1, is
85 A or greater per phase
but did so more than 26
calendar months and less
than or equal to 28 calendar
months of receiving GIC flow
information specified in
Requirement R9, Part 9.1
OR
(and including) 15% or three
of its solely owned and
jointly owned applicable BES
power transformers
(whichever is greater) where
the maximum effective GIC
value provided in
Requirement R9, Part 9.1, is
85 A or greater per phase;
OR
The responsible entity
conducted a supplemental
thermal impact assessment
for its solely owned and
jointly owned applicable BES
power transformers where
the maximum effective GIC
value provided in
Requirement R9, Part 9.1, is
85 A or greater per phase
but did so more than 28
calendar months and less
than or equal to 30 calendar
months of receiving GIC flow
information specified in
Requirement R9, Part 9.1;
OR
than three of its solely
owned and jointly owned
applicable BES power
transformers (whichever is
greater) where the
maximum effective GIC
value provided in
Requirement R9, Part 9.1, is
85 A or greater per phase;
OR
The responsible entity
conducted a supplemental
thermal impact assessment
for its solely owned and
jointly owned applicable BES
power transformers where
the maximum effective GIC
value provided in
Requirement R9, Part 9.1, is
85 A or greater per phase
but did so more than 30
calendar months of receiving
GIC flow information
specified in Requirement R9,
Part 9.1;
OR
Page 18 of 40
TPL‐007‐2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
R#
Violation Severity Levels
Lower VSL
R11.
R12.
N/A
N/A
Moderate VSL
High VSL
Severe VSL
The responsible entity failed
to include one of the
required elements as listed
in Requirement R10, Parts
10.1 through 10.3.
The responsible entity failed
to include two of the
required elements as listed
in Requirement R10, Parts
10.1 through 10.3.
The responsible entity failed
to include three of the
required elements as listed
in Requirement R10, Parts
10.1 through 10.3.
N/A
The responsible entity did
not implement a process to
obtain GIC monitor data
from at least one GIC
monitor located in the
Planning Coordinator’s
planning area or other part
of the system included in the
Planning Coordinator’s GIC
System Model.
N/A
The responsible entity did
not implement a process to
obtain geomagnetic field
data for its Planning
Coordinator’s planning area.
N/A
N/A
D. Regional Variances
None.
E. Associated Documents
Attachment 1
Page 19 of 40
TPL‐007‐2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
Version History
Version
1
2
Date
Action
Change
Tracking
December 17,
Adopted by the NERC Board of Trustees
2014
New
November 9,
Adopted by the NERC Board of Trustees
2017
Revised to
respond to
directives in FERC
Order No. 830.
Page 20 of 40
TPL‐007‐2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
Attachment 1
Calculating Geoelectric Fields for the Benchmark and Supplemental GMD Events
The benchmark GMD event1 defines the geoelectric field values used to compute GIC flows that
are needed to conduct a benchmark GMD Vulnerability Assessment. It is composed of the
following elements: (1) a reference peak geoelectric field amplitude of 8 V/km derived from
statistical analysis of historical magnetometer data; (2) scaling factors to account for local
geomagnetic latitude; (3) scaling factors to account for local earth conductivity; and (4) a
reference geomagnetic field time series or waveform to facilitate time‐domain analysis of GMD
impact on equipment.
The supplemental GMD event is composed of similar elements as described above, except (1) the
reference peak geoelectric field amplitude is 12 V/km over a localized area; and (2) the
geomagnetic field time series or waveform includes a local enhancement in the waveform.2
The regional geoelectric field peak amplitude used in GMD Vulnerability Assessment, Epeak, can
be obtained from the reference geoelectric field value of 8 V/km for the benchmark GMD event
(1) or 12 V/km for the supplemental GMD event (2) using the following relationships:
8
12
⁄
⁄
(1)
(2)
where, α is the scaling factor to account for local geomagnetic latitude, and β is a scaling factor
to account for the local earth conductivity structure. Subscripts b and s for the β scaling factor
denote association with the benchmark or supplemental GMD events, respectively.
Scaling the Geomagnetic Field
The benchmark and supplemental GMD events are defined for geomagnetic latitude of 60 and
must be scaled to account for regional differences based on geomagnetic latitude. Table 2
provides a scaling factor correlating peak geoelectric field to geomagnetic latitude. Alternatively,
the scaling factor is computed with the empirical expression:
0.001
.
(3)
where, L is the geomagnetic latitude in degrees and 0.1 ≤ α ≤ 1.
1 The Benchmark Geomagnetic Disturbance Event Description, May 2016 is available on the Related Information webpage for
TPL‐007‐1: http://www.nerc.com/pa/Stand/TPL0071RD/Benchmark_clean_May12_complete.pdf.
2 The extent of local enhancements is on the order of 100 km in North‐South (latitude) direction but longer in East‐West
(longitude) direction. The local enhancement in the geomagnetic field occurs over the time period of 2‐5 minutes. Additional
information is available in the Supplemental Geomagnetic Disturbance Event Description, October 2017 white paper on the
Project 2013‐03 Geomagnetic Disturbance Mitigation project webpage: http://www.nerc.com/pa/Stand/Pages/Project‐2013‐
03‐Geomagnetic‐Disturbance‐Mitigation.aspx.
Page 21 of 40
TPL‐007‐2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
For large planning areas that cover more than one scaling factor from Table 2, the GMD
Vulnerability Assessment should be based on a peak geoelectric field that is:
calculated by using the most conservative (largest) value for α; or
calculated assuming a non‐uniform or piecewise uniform geomagnetic field.
Table 2: Geomagnetic Field Scaling Factors for the
Benchmark and Supplemental GMD
Events
Geomagnetic Latitude
(Degrees)
Scaling Factor1
()
≤ 40
0.10
45
0.2
50
0.3
54
0.5
56
0.6
57
0.7
58
0.8
59
0.9
≥ 60
1.0
Scaling the Geoelectric Field
The benchmark GMD event is defined for the reference Quebec earth model described in Table
4. The peak geoelectric field, Epeak, used in a GMD Vulnerability Assessment may be obtained by
either:
Calculating the geoelectric field for the ground conductivity in the planning area and the
reference geomagnetic field time series scaled according to geomagnetic latitude, using
a procedure such as the plane wave method described in the NERC GMD Task Force GIC
Application Guide;3 or
Using the earth conductivity scaling factor β from Table 3 that correlates to the ground
conductivity map in Figure 1 or Figure 2. Along with the scaling factor from equation
(3) or Table 2, β is applied to the reference geoelectric field using equation (1 or 2, as
applicable) to obtain the regional geoelectric field peak amplitude Epeak to be used in
GMD Vulnerability Assessments. When a ground conductivity model is not available, the
planning entity should use the largest β factor of adjacent physiographic regions or a
technically justified value.
3 Available at the NERC GMD Task Force project webpage: http://www.nerc.com/comm/PC/Pages/Geomagnetic‐Disturbance‐
Task‐Force‐(GMDTF)‐2013.aspx.
Page 22 of 40
TPL‐007‐2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
The earth models used to calculate Table 3 for the United States were obtained from publicly
available information published on the U. S. Geological Survey website.4 The models used to
calculate Table 3 for Canada were obtained from Natural Resources Canada (NRCan) and reflect
the average structure for large regions. A planner can also use specific earth model(s) with
documented justification and the reference geomagnetic field time series to calculate the β
factor(s) as follows:
⁄8 for the benchmark GMD event
(4)
⁄12 for the supplemental GMD
(5)
where, E is the absolute value of peak geoelectric in V/km obtained from the technically justified
earth model and the reference geomagnetic field time series.
For large planning areas that span more than one β scaling factor, the most conservative (largest)
value for β may be used in determining the peak geoelectric field to obtain conservative results.
Alternatively, a planner could perform analysis using a non‐uniform or piecewise uniform
geoelectric field.
Applying the Localized Peak Geoelectric Field in the Supplemental GMD Event
The peak geoelectric field of the supplemental GMD event occurs in a localized area.5 Planners
have flexibility to determine how to apply the localized peak geoelectric field over the planning
area in performing GIC calculations. Examples of approaches are:
Apply the peak geoelectric field (12 V/km scaled to the planning area) over the entire
planning area;
Apply a spatially limited (12 V/km scaled to the planning area) peak geoelectric field (e.g.,
100 km in North‐South latitude direction and 500 km in East‐West longitude direction)
over a portion(s) of the system, and apply the benchmark GMD event over the rest of the
system; or
Other methods to adjust the benchmark GMD event analysis to account for the localized
geoelectric field enhancement of the supplemental GMD event.
4 Available at http://geomag.usgs.gov/conductivity/.
5 See the Supplemental Geomagnetic Disturbance Description white paper located on the Project 2013‐03 Geomagnetic
Disturbance Mitigation project webpage: http://www.nerc.com/pa/Stand/Pages/Project‐2013‐03‐Geomagnetic‐Disturbance‐
Mitigation.aspx.
Page 23 of 40
TPL‐007‐2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
Figure 1: Physiographic Regions of the Continental United States6
Figure 2: Physiographic Regions of Canada
6 Additional map detail is available at the U.S. Geological Survey: http://geomag.usgs.gov/.
Page 24 of 40
TPL‐007‐2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
Table 3: Geoelectric Field Scaling Factors
Earth model
Scaling Factor
Benchmark Event
(b)
Scaling Factor
Supplemental
Event
(s)
AK1A
0.56
0.51
AK1B
0.56
0.51
AP1
0.33
0.30
AP2
0.82
0.78
BR1
0.22
0.22
CL1
0.76
0.73
CO1
0.27
0.25
CP1
0.81
0.77
CP2
0.95
0.86
FL1
0.76
0.73
CS1
0.41
0.37
IP1
0.94
0.90
IP2
0.28
0.25
IP3
0.93
0.90
IP4
0.41
0.35
NE1
0.81
0.77
PB1
0.62
0.55
PB2
0.46
0.39
PT1
1.17
1.19
SL1
0.53
0.49
SU1
0.93
0.90
BOU
0.28
0.24
FBK
0.56
0.56
PRU
0.21
0.22
BC
0.67
0.62
PRAIRIES
0.96
0.88
SHIELD
1.0
1.0
ATLANTIC
0.79
0.76
Page 25 of 40
TPL‐007‐2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
Rationale: Scaling factors in Table 3 are dependent upon the frequency content of the
reference storm. Consequently, the benchmark GMD event and the supplemental GMD event
may produce different scaling factors for a given earth model.
The scaling factor associated with the benchmark GMD event for the Florida earth model (FL1)
has been updated based on the earth model published on the USGS public website.
Table 4: Reference Earth Model (Quebec)
Layer Thickness (km)
Resistivity (Ω-m)
15
20,000
10
200
125
1,000
200
100
∞
3
Reference Geomagnetic Field Time Series or Waveform for the Benchmark GMD
Event7
The geomagnetic field measurement record of the March 13‐14 1989 GMD event, measured at
the NRCan Ottawa geomagnetic observatory, is the basis for the reference geomagnetic field
waveform to be used to calculate the GIC time series, GIC(t), required for transformer thermal
impact assessment.
The geomagnetic latitude of the Ottawa geomagnetic observatory is 55; therefore, the
amplitudes of the geomagnetic field measurement data were scaled up to the 60 reference
geomagnetic latitude (see Figure 3) such that the resulting peak geoelectric field amplitude
computed using the reference earth model was 8 V/km (see Figures 4 and 5). The sampling rate
for the geomagnetic field waveform is 10 seconds.8 To use this geoelectric field time series when
a different earth model is applicable, it should be scaled with the appropriate benchmark
conductivity scaling factor b.
7 Refer to the Benchmark Geomagnetic Disturbance Event Description white paper for details on the determination of the
reference geomagnetic field waveform: http://www.nerc.com/pa/stand/Pages/TPL0071RI.aspx.
8 The data file of the benchmark geomagnetic field waveform is available on the Related Information webpage for TPL‐007‐1:
http://www.nerc.com/pa/stand/Pages/TPL0071RI.aspx.
Page 26 of 40
TPL‐007‐2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
Figure 3: Benchmark Geomagnetic Field Waveform
Red Bn (Northward), Blue Be (Eastward)
Figure 4: Benchmark Geoelectric Field Waveform
EE (Eastward)
Page 27 of 40
TPL‐007‐2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
Figure 5: Benchmark Geoelectric Field Waveform
EN (Northward)
Reference Geomagnetic Field Time Series or Waveform for the Supplemental GMD
Event9
The geomagnetic field measurement record of the March 13‐14, 1989 GMD event, measured at
the NRCan Ottawa geomagnetic observatory, is the basis for the reference geomagnetic field
waveform to be used to calculate the GIC time series, GIC(t), required for transformer thermal
impact assessment for the supplemental GMD event. The supplemental GMD event waveform
differs from the benchmark GMD event waveform in that the supplemental GMD event
waveform has a local enhancement.
The geomagnetic latitude of the Ottawa geomagnetic observatory is 55; therefore, the
amplitudes of the geomagnetic field measurement data were scaled up to the 60 reference
geomagnetic latitude (see Figure 6) such that the resulting peak geoelectric field amplitude
computed using the reference earth model was 12 V/km (see Figure7). The sampling rate for the
geomagnetic field waveform is 10 seconds.10 To use this geoelectric field time series when a
different earth model is applicable, it should be scaled with the appropriate supplemental
conductivity scaling factor s.
9 Refer to the Supplemental Geomagnetic Disturbance Event Description white paper for details on the determination of the
reference geomagnetic field waveform: http://www.nerc.com/pa/Stand/Pages/Project‐2013‐03‐Geomagnetic‐Disturbance‐
Mitigation.aspx.
10 The data file of the benchmark geomagnetic field waveform is available on the NERC GMD Task Force project webpage:
http://www.nerc.com/comm/PC/Pages/Geomagnetic‐Disturbance‐Task‐Force‐(GMDTF)‐2013.aspx.
Page 28 of 40
TPL‐007‐2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
4000
2000
Time (min)
200
400
600
800
1000
1200
1400
1600
1800
2000
Bx, By (nT)
0
-2000
-4000
-6000
-8000
-10000
Figure 6: Supplemental Geomagnetic Field Waveform
Red BN (Northward), Blue BE (Eastward)
Figure 7: Supplemental Geoelectric Field Waveform
Blue EN (Northward), Red EE (Eastward)
Page 29 of 40
TPL‐007‐2 – Supplemental Material
Guidelines and Technical Basis
The diagram below provides an overall view of the GMD Vulnerability Assessment process:
The requirements in this standard cover various aspects of the GMD Vulnerability Assessment
process.
Benchmark GMD Event (Attachment 1)
The benchmark GMD event defines the geoelectric field values used to compute GIC flows that
are needed to conduct a benchmark GMD Vulnerability Assessment. The Benchmark
Geomagnetic Disturbance Event Description, May 201611 white paper includes the event
description, analysis, and example calculations.
Supplemental GMD Event (Attachment 1)
The supplemental GMD event defines the geoelectric field values used to compute GIC flows that
are needed to conduct a supplemental GMD Vulnerability Assessment. The Supplemental
Geomagnetic Disturbance Event Description, October 201712 white paper includes the event
description and analysis.
Requirement R2
A GMD Vulnerability Assessment requires a GIC System model, which is a dc representation of
the System, to calculate GIC flow. In a GMD Vulnerability Assessment, GIC simulations are used
to determine transformer Reactive Power absorption and transformer thermal response. Details
for developing the GIC System model are provided in the NERC GMD Task Force guide:
Application Guide for Computing Geomagnetically‐Induced Current in the Bulk Power System,
December 2013.13
Underground pipe‐type cables present a special modeling situation in that the steel pipe that
encloses the power conductors significantly reduces the geoelectric field induced into the
11 http://www.nerc.com/pa/stand/Pages/TPL0071RI.aspx.
12
http://www.nerc.com/pa/Stand/Pages/Project‐2013‐03‐Geomagnetic‐Disturbance‐Mitigation.aspx.
http://www.nerc.com/comm/PC/Geomagnetic%20Disturbance%20Task%20Force%20GMDTF%202013/GIC%20Application
%20Guide%202013_approved.pdf.
13
Page 30 of 40
TPL‐007‐2 – Supplemental Material
conductors themselves, while they remain a path for GIC. Solid dielectric cables that are not
enclosed by a steel pipe will not experience a reduction in the induced geoelectric field. A
planning entity should account for special modeling situations in the GIC system model, if
applicable.
Requirement R4
The Geomagnetic Disturbance Planning Guide,14 December 2013 developed by the NERC GMD
Task Force provides technical information on GMD‐specific considerations for planning studies.
Requirement R5
The benchmark thermal impact assessment of transformers specified in Requirement R6 is based
on GIC information for the benchmark GMD Event. This GIC information is determined by the
planning entity through simulation of the GIC System model and must be provided to the entity
responsible for conducting the thermal impact assessment. GIC information should be provided
in accordance with Requirement R5 each time the GMD Vulnerability Assessment is performed
since, by definition, the GMD Vulnerability Assessment includes a documented evaluation of
susceptibility to localized equipment damage due to GMD.
The maximum effective GIC value provided in Part 5.1 is used for the benchmark thermal impact
assessment. Only those transformers that experience an effective GIC value of 75 A or greater
per phase require evaluation in Requirement R6.
GIC(t) provided in Part 5.2 is used to convert the steady state GIC flows to time‐series GIC data
for the benchmark thermal impact assessment of transformers. This information may be needed
by one or more of the methods for performing a benchmark thermal impact assessment.
Additional information is in the following section and the Transformer Thermal Impact
Assessment White Paper,15 October 2017.
The peak GIC value of 75 Amps per phase has been shown through thermal modeling to be a
conservative threshold below which the risk of exceeding known temperature limits established
by technical organizations is low.
Requirement R6
The benchmark thermal impact assessment of a power transformer may be based on
manufacturer‐provided GIC capability curves, thermal response simulation, thermal impact
screening, or other technically justified means. Approaches for conducting the assessment are
presented in the Transformer Thermal Impact Assessment White Paper ERO Enterprise‐Endorsed
14
http://www.nerc.com/comm/PC/Geomagnetic%20Disturbance%20Task%20Force%20GMDTF%202013/GMD%20Planning
%20Guide_approved.pdf.
15 http://www.nerc.com/pa/Stand/Pages/Project‐2013‐03‐Geomagnetic‐Disturbance‐Mitigation.aspx.
Page 31 of 40
TPL‐007‐2 – Supplemental Material
Implementation Guidance16 for this requirement. This ERO‐Endorsed document is posted on the
NERC Compliance Guidance17 webpage.
Transformers are exempt from the benchmark thermal impact assessment requirement if the
effective GIC value for the transformer is less than 75 A per phase, as determined by a GIC analysis
of the System. Justification for this criterion is provided in the Screening Criterion for Transformer
Thermal Impact Assessment White Paper,18 October 2017. A documented design specification
exceeding this value is also a justifiable threshold criterion that exempts a transformer from
Requirement R6.
The benchmark threshold criteria and its associated transformer thermal impact must be
evaluated on the basis of effective GIC. Refer to the white papers for additional information.
Requirement R7
Technical considerations for GMD mitigation planning, including operating and equipment
strategies, are available in Chapter 5 of the Geomagnetic Disturbance Planning Guide,19
December 2013. Additional information is available in the 2012 Special Reliability Assessment
Interim Report: Effects of Geomagnetic Disturbances on the Bulk‐Power System, 20 February 2012.
Requirement R8
The Geomagnetic Disturbance Planning Guide,21 December 2013 developed by the NERC GMD
Task Force provides technical information on GMD‐specific considerations for planning studies.
The supplemental GMD Vulnerability Assessment process is similar to the benchmark GMD
Vulnerability Assessment process described under Requirement R4.
Requirement R9
The supplemental thermal impact assessment specified of transformers in Requirement R10 is
based on GIC information for the supplemental GMD Event. This GIC information is determined
by the planning entity through simulation of the GIC System model and must be provided to the
entity responsible for conducting the thermal impact assessment. GIC information should be
provided in accordance with Requirement R9 each time the GMD Vulnerability Assessment is
performed since, by definition, the GMD Vulnerability Assessment includes a documented
evaluation of susceptibility to localized equipment damage due to GMD.
16 http://www.nerc.com/pa/comp/guidance/EROEndorsedImplementationGuidance/TPL‐007‐1_Transformer_Thermal_Impact_
Assessment_White_Paper.pdf.
17 http://www.nerc.com/pa/comp/guidance/Pages/default.aspx.
18 http://www.nerc.com/pa/Stand/Pages/Project‐2013‐03‐Geomagnetic‐Disturbance‐Mitigation.aspx.
19 http://www.nerc.com/comm/PC/Geomagnetic%20Disturbance%20Task%20Force%20GMDTF%202013/GMD%20Planning
%20Guide_approved.pdf.
20 http://www.nerc.com/pa/RAPA/ra/Reliability%20Assessments%20DL/2012GMD.pdf.
21 http://www.nerc.com/comm/PC/Geomagnetic%20Disturbance%20Task%20Force%20GMDTF%202013/GMD%20Planning
%20Guide_approved.pdf.
Page 32 of 40
TPL‐007‐2 – Supplemental Material
The maximum effective GIC value provided in Part 9.1 is used for the supplemental thermal
impact assessment. Only those transformers that experience an effective GIC value of 85 A or
greater per phase require evaluation in Requirement R10.
GIC(t) provided in Part 9.2 is used to convert the steady state GIC flows to time‐series GIC data
for the supplemental thermal impact assessment of transformers. This information may be
needed by one or more of the methods for performing a supplemental thermal impact
assessment. Additional information is in the following section.
The peak GIC value of 85 Amps per phase has been shown through thermal modeling to be a
conservative threshold below which the risk of exceeding known temperature limits established
by technical organizations is low.
Requirement R10
The supplemental thermal impact assessment of a power transformer may be based on
manufacturer‐provided GIC capability curves, thermal response simulation, thermal impact
screening, or other technically justified means. Approaches for conducting the assessment are
presented in the Transformer Thermal Impact Assessment White Paper ERO Enterprise‐Endorsed
Implementation Guidance22 discussed in the Requirement R6 section above. A later version of the
Transformer Thermal Impact Assessment White Paper,23 October 2017, has been developed to
include updated information pertinent to the supplemental GMD event and supplemental
thermal impact assessment.
Transformers are exempt from the supplemental thermal impact assessment requirement if the
effective GIC value for the transformer is less than 85 A per phase, as determined by a GIC analysis
of the System. Justification for this criterion is provided in the revised Screening Criterion for
Transformer Thermal Impact Assessment White Paper,24 October 2017. A documented design
specification exceeding this value is also a justifiable threshold criterion that exempts a
transformer from Requirement R10.
The supplemental threshold criteria and its associated transformer thermal impact must be
evaluated on the basis of effective GIC. Refer to the white papers for additional information.
Requirement R11
Technical considerations for GIC monitoring are contained in Chapter 6 of the 2012 Special
Reliability Assessment Interim Report: Effects of Geomagnetic Disturbances on the Bulk‐Power
System, 25 February 2012. GIC monitoring is generally performed by Hall effect transducers that
are attached to the neutral of the wye‐grounded transformer. Data from GIC monitors is useful
for model validation and situational awareness.
22 http://www.nerc.com/pa/comp/guidance/EROEndorsedImplementationGuidance/TPL‐007‐1_Transformer_Thermal_Impact_
Assessment_White_Paper.pdf.
23 http://www.nerc.com/pa/Stand/Pages/Project‐2013‐03‐Geomagnetic‐Disturbance‐Mitigation.aspx.
24 http://www.nerc.com/pa/Stand/Pages/Project‐2013‐03‐Geomagnetic‐Disturbance‐Mitigation.aspx.
25 http://www.nerc.com/pa/RAPA/ra/Reliability%20Assessments%20DL/2012GMD.pdf.
Page 33 of 40
TPL‐007‐2 – Supplemental Material
Responsible entities consider the following in developing a process for obtaining GIC monitor
data:
Monitor locations. An entity's operating process may be constrained by location of
existing GIC monitors. However, when planning for additional GIC monitoring installations
consider that data from monitors located in areas found to have high GIC based on system
studies may provide more useful information for validation and situational awareness
purposes. Conversely, data from GIC monitors that are located in the vicinity of
transportation systems using direct current (e.g., subways or light rail) may be unreliable.
Monitor specifications. Capabilities of Hall effect transducers, existing and planned,
should be considered in the operating process. When planning new GIC monitor
installations, consider monitor data range (e.g., ‐500 A through + 500 A) and ambient
temperature ratings consistent with temperatures in the region in which the monitor will
be installed.
Sampling Interval. An entity's operating process may be constrained by capabilities of
existing GIC monitors. However, when possible specify data sampling during periods of
interest at a rate of 10 seconds or faster.
Collection Periods. The process should specify when the entity expects GIC data to be
collected. For example, collection could be required during periods where the Kp index is
above a threshold, or when GIC values are above a threshold. Determining when to
discontinue collecting GIC data should also be specified to maintain consistency in data
collection.
Data format. Specify time and value formats. For example, Greenwich Mean Time (GMT)
(MM/DD/YYYY HH:MM:SS) and GIC Value (Ampere). Positive (+) and negative (‐) signs
indicate direction of GIC flow. Positive reference is flow from ground into transformer
neutral. Time fields should indicate the sampled time rather than system or SCADA time
if supported by the GIC monitor system.
Data retention. The entity's process should specify data retention periods, for example 1
year. Data retention periods should be adequately long to support availability for the
entity's model validation process and external reporting requirements, if any.
Additional information. The entity's process should specify collection of other
information necessary for making the data useful, for example monitor location and type
of neutral connection (e.g., three‐phase or single‐phase).
Requirement R12
Magnetometers measure changes in the earth's magnetic field. Entities should obtain data from
the nearest accessible magnetometer. Sources of magnetometer data include:
Page 34 of 40
TPL‐007‐2 – Supplemental Material
Observatories such as those operated by U.S. Geological Survey and Natural Resources
Canada, see figure below for locations:26
Research institutions and academic universities;
Entities with installed magnetometers.
Entities that choose to install magnetometers should consider equipment specifications and data
format protocols contained in the latest version of the INTERMAGNET Technical Reference
Manual, Version 4.6, 2012.27
26
27
http://www.intermagnet.org/index‐eng.php.
http://www.intermagnet.org/publications/intermag_4‐6.pdf.
Page 35 of 40
TPL‐007‐2 – Supplemental Material
Rationale
During development of TPL‐007‐1, text boxes were embedded within the standard to explain the
rationale for various parts of the standard. The text from the rationale text boxes was moved to
this section upon approval of TPL‐007‐1 by the NERC Board of Trustees. In developing TPL‐007‐2,
the SDT has made changes to the sections below only when necessary for clarity. Changes are
marked with brackets [ ].
Rationale for Applicability:
Instrumentation transformers and station service transformers do not have significant impact on
geomagnetically‐induced current (GIC) flows; therefore, these transformers are not included in
the applicability for this standard.
Terminal voltage describes line‐to‐line voltage.
Rationale for R1:
In some areas, planning entities may determine that the most effective approach to conduct a
GMD Vulnerability Assessment is through a regional planning organization. No requirement in
the standard is intended to prohibit a collaborative approach where roles and responsibilities are
determined by a planning organization made up of one or more Planning Coordinator(s).
Rationale for R2:
A GMD Vulnerability Assessment requires a GIC System model to calculate GIC flow which is used
to determine transformer Reactive Power absorption and transformer thermal response.
Guidance for developing the GIC System model is provided in the Application Guide Computing
Geomagnetically‐Induced Current in the Bulk‐Power System,28 December 2013, developed by the
NERC GMD Task Force.
The System model specified in Requirement R2 is used in conducting steady state power flow
analysis that accounts for the Reactive Power absorption of power transformer(s) due to GIC in
the System.
The GIC System model includes all power transformer(s) with a high side, wye‐grounded winding
with terminal voltage greater than 200 kV. The model is used to calculate GIC flow in the network.
The projected System condition for GMD planning may include adjustments to the System that
are executable in response to space weather information. These adjustments could include, for
example, recalling or postponing maintenance outages.
The Violation Risk Factor (VRF) for Requirement R2 is changed from Medium to High. This change
is for consistency with the VRF for approved standard TPL‐001‐4 Requirement R1, which is
proposed for revision in the NERC filing dated August 29, 2014 (Docket No. RM12‐1‐000). NERC
guidelines require consistency among Reliability Standards.
28
http://www.nerc.com/comm/PC/Geomagnetic%20Disturbance%20Task%20Force%20GMDTF%202013/GIC%20Application
%20Guide%202013_approved.pdf.
Page 36 of 40
TPL‐007‐2 – Supplemental Material
Rationale for R3:
Requirement R3 allows a responsible entity the flexibility to determine the System steady state
voltage criteria for System steady state performance in Table 1. Steady state voltage limits are
an example of System steady state performance criteria.
Rationale for R4:
The GMD Vulnerability Assessment includes steady state power flow analysis and the supporting
study or studies using the models specified in Requirement R2 that account for the effects of GIC.
Performance criteria are specified in Table 1.
At least one System On‐Peak Load and at least one System Off‐Peak Load must be examined in
the analysis.
Distribution of GMD Vulnerability Assessment results provides a means for sharing relevant
information with other entities responsible for planning reliability. Results of GIC studies may
affect neighboring systems and should be taken into account by planners.
The Geomagnetic Disturbance Planning Guide,29 December 2013 developed by the NERC GMD
Task Force provides technical information on GMD‐specific considerations for planning studies.
The provision of information in Requirement R4, Part 4.3, shall be subject to the legal and
regulatory obligations for the disclosure of confidential and/or sensitive information.
Rationale for R5:
This GIC information is necessary for determining the thermal impact of GIC on transformers in
the planning area and must be provided to entities responsible for performing the thermal impact
assessment so that they can accurately perform the assessment. GIC information should be
provided in accordance with Requirement R5 as part of the GMD Vulnerability Assessment
process since, by definition, the GMD Vulnerability Assessment includes documented evaluation
of susceptibility to localized equipment damage due to GMD.
The maximum effective GIC value provided in Part 5.1 is used for transformer thermal impact
assessment.
GIC(t) provided in Part 5.2 can alternatively be used to convert the steady state GIC flows to time‐
series GIC data for transformer thermal impact assessment. This information may be needed by
one or more of the methods for performing a thermal impact assessment. Additional guidance is
available in the Transformer Thermal Impact Assessment White Paper,30 October 2017.
A Transmission Owner or Generator Owner that desires GIC(t) may request it from the planning
entity. The planning entity shall provide GIC(t) upon request once GIC has been calculated, but
29
http://www.nerc.com/comm/PC/Geomagnetic%20Disturbance%20Task%20Force%20GMDTF%202013/GMD%20Planning
%20Guide_approved.pdf.
30 http://www.nerc.com/pa/Stand/Pages/Project‐2013‐03‐Geomagnetic‐Disturbance‐Mitigation.aspx.
Page 37 of 40
TPL‐007‐2 – Supplemental Material
no later than 90 calendar days after receipt of a request from the owner and after completion of
Requirement R5, Part 5.1.
The provision of information in Requirement R5 shall be subject to the legal and regulatory
obligations for the disclosure of confidential and/or sensitive information.
Rationale for R6:
The transformer thermal impact screening criterion has been revised from 15 A per phase to 75
A per phase [for the benchmark GMD event]. Only those transformers that experience an
effective GIC value of 75 A per phase or greater require evaluation in Requirement R6. The
justification is provided in the Screening Criterion for Transformer Thermal Impact Assessment
White Paper,31 October 2017.
The thermal impact assessment may be based on manufacturer‐provided GIC capability curves,
thermal response simulation, thermal impact screening, or other technically justified means. The
transformer thermal assessment will be repeated or reviewed using previous assessment results
each time the planning entity performs a GMD Vulnerability Assessment and provides GIC
information as specified in Requirement R5. Approaches for conducting the assessment are
presented in the Transformer Thermal Impact Assessment White Paper,32 October 2017.
Thermal impact assessments are provided to the planning entity, as determined in Requirement
R1, so that identified issues can be included in the GMD Vulnerability Assessment (R4), and the
Corrective Action Plan (R7) as necessary.
Thermal impact assessments of non‐BES transformers are not required because those
transformers do not have a wide‐area effect on the reliability of the interconnected Transmission
system.
The provision of information in Requirement R6, Part 6.4, shall be subject to the legal and
regulatory obligations for the disclosure of confidential and/or sensitive information.
Rationale for R7:
The proposed requirement addresses directives in Order No. 830 for establishing Corrective
Action Plan (CAP) deadlines associated with GMD Vulnerability Assessments. In Order No. 830,
FERC directed revisions to TPL‐007 such that CAPs are developed within one year from the
completion of GMD Vulnerability Assessments (P 101). Furthermore, FERC directed
establishment of implementation deadlines after the completion of the CAP as follows (P 102):
Two years for non‐hardware mitigation; and
Four years for hardware mitigation.
The objective of Part 7.4 is to provide awareness to potentially impacted entities when
implementation of planned mitigation is not achievable within the deadlines established in Part
31
32
http://www.nerc.com/pa/Stand/Pages/Project‐2013‐03‐Geomagnetic‐Disturbance‐Mitigation.aspx.
http://www.nerc.com/pa/Stand/Pages/Project‐2013‐03‐Geomagnetic‐Disturbance‐Mitigation.aspx.
Page 38 of 40
TPL‐007‐2 – Supplemental Material
7.3. Examples of situations beyond the control of the of the responsible entity (see Section 7.4)
include, but are not limited to:
Delays resulting from regulatory/legal processes, such as permitting;
Delays resulting from stakeholder processes required by tariff;
Delays resulting from equipment lead times; or
Delays resulting from the inability to acquire necessary Right‐of‐Way.
Rationale for Table 3:
Table 3 has been revised to use the same ground model designation, FL1, as is being used by
USGS. The calculated scaling factor for FL1 is 0.74. [The scaling factor associated with the
benchmark GMD event for the Florida earth model (FL1) has been updated to 0.76 in TPL‐007‐2
based on the earth model published on the USGS public website.]
Rationale for R8 – R10:
The proposed requirements address directives in Order No. 830 for revising the benchmark GMD
event used in GMD Vulnerability Assessments (P 44, P 47‐49). The requirements add a
supplemental GMD Vulnerability Assessment based on the supplemental GMD event that
accounts for localized peak geoelectric fields.
Rationale for R11 – R12:
The proposed requirements address directives in Order No. 830 for requiring responsible
entities to collect GIC monitoring and magnetometer data as necessary to enable model
validation and situational awareness (P 88; P. 90‐92). GMD measurement data refers to GIC
monitor data and geomagnetic field data in Requirements R11 and R12, respectively. See the
Guidelines and Technical Basis section of this standard for technical information.
The objective of Requirement R11 is for entities to obtain GIC data for the Planning
Coordinator's planning area or other part of the system included in the Planning Coordinator's
GIC System model to inform GMD Vulnerability Assessments. Technical considerations for GIC
monitoring are contained in Chapter 9 of the 2012 Special Reliability Assessment Interim
Report: Effects of Geomagnetic Disturbances on the Bulk‐Power System (NERC 2012 GMD
Report). GIC monitoring is generally performed by Hall effect transducers that are attached to
the neutral of the transformer and measure dc current flowing through the neutral.
The objective of Requirement R12 is for entities to obtain geomagnetic field data for the
Planning Coordinator's planning area to inform GMD Vulnerability Assessments.
Magnetometers provide geomagnetic field data by measuring changes in the earth's magnetic
field. Sources of geomagnetic field data include:
Observatories such as those operated by U.S. Geological Survey, Natural Resources
Canada, research organizations, or university research facilities;
Installed magnetometers; and
Commercial or third‐party sources of geomagnetic field data.
Page 39 of 40
TPL‐007‐2 – Supplemental Material
Geomagnetic field data for a Planning Coordinator’s planning area is obtained from one or more
of the above data sources located in the Planning Coordinator’s planning area, or by obtaining a
geomagnetic field data product for the Planning Coordinator’s planning area from a government
or research organization. The geomagnetic field data product does not need to be derived from
a magnetometer or observatory within the Planning Coordinator’s planning area.
Page 40 of 40
Proposed Reliability Standard TPL-007-2 – Transmission System Planned Performance for
Geomagnetic Disturbance Operations - Redline
TPL-007-1 2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
Standard Development Timeline
This section is maintained by the drafting team during the development of the standard and will be removed when the standard is
adopted by the NERC Board of Trustees (Board).
Description of Current Draft
Completed Actions
Date
Standards Committee approved Standard Authorization Request
(SAR) for posting
December 14, 2016
SAR posted for comment
December 16, 2016 –
January 20, 2017
45-day formal comment period with initial ballot
June 28 – August 11,
2017
Anticipated Actions
Date
10-day final ballot
October 2017
Board adoption
November 2017
Draft 2 of TPL-007-2
October 2017
Page 1 of 48
TPL-007-1 2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
New or Modified Term(s) Used in NERC Reliability Standards
This section includes all new or modified terms used in the proposed standard that will be included in the Glossary of Terms Used in
NERC Reliability Standards upon applicable regulatory approval. Terms used in the proposed standard that are already defined and
are not being modified can be found in the Glossary of Terms Used in NERC Reliability Standards. The new or revised terms listed
below will be presented for approval with the proposed standard. Upon Board adoption, this section will be removed.
Term(s):
None
Draft 2 of TPL-007-2
October 2017
Page 2 of 48
TPL-007-1 2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
Upon Board adoption, the rationale boxes will be moved to the Supplemental Material Section.
A. Introduction
1.
Title:
Transmission System Planned Performance for Geomagnetic Disturbance Events
2.
Number:
TPL-007-12
3.
Purpose:
events.
Establish requirements for Transmission system planned performance during geomagnetic disturbance (GMD)
4.
Applicability:
4.1. Functional Entities:
4.1.1. Planning Coordinator with a planning area that includes a Facility or Facilities specified in 4.2;
4.1.2. Transmission Planner with a planning area that includes a Facility or Facilities specified in 4.2;
4.1.3. Transmission Owner who owns a Facility or Facilities specified in 4.2; and
4.1.4. Generator Owner who owns a Facility or Facilities specified in 4.2.
4.2. Facilities:
4.2.1. Facilities that include power transformer(s) with a high side, wye-grounded winding with terminal voltage
greater than 200 kV.
5.
Effective Date: See Implementation Plan for TPL-007-12.
6.
Background: During a GMD event, geomagnetically-induced currents (GIC) may cause transformer hot-spot heating or
damage, loss of Reactive Power sources, increased Reactive Power demand, and Misoperation(s), the combination of
which may result in voltage collapse and blackout.
Draft 2 of TPL-007-2
October 2017
Page 3 of 48
TPL-007-1 2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
B. Requirements and Measures
R1. Each Planning Coordinator, in conjunction with its Transmission Planner(s), shall identify the individual and joint
responsibilities of the Planning Coordinator and Transmission Planner(s) in the Planning Coordinator’s planning area for
maintaining models, and performing the study or studies needed to complete benchmark and supplemental GMD
Vulnerability Assessment(s), and implementing process(es) to obtain GMD measurement data as specified in this standard.
[Violation Risk Factor: Lower] [Time Horizon: Long-term Planning]
M1. Each Planning Coordinator, in conjunction with its Transmission Planners, shall provide documentation on roles and
responsibilities, such as meeting minutes, agreements, copies of procedures or protocols in effect between entities or
between departments of a vertically integrated system, or email correspondence that identifies an agreement has been
reached on individual and joint responsibilities for maintaining models, and performing the study or studies needed to
complete benchmark and supplemental GMD Vulnerability Assessment(s), and implementing process(es) to obtain GMD
measurement data in accordance with Requirement R1.
R2. Each responsible entity, as determined in Requirement R1, shall maintain System models and GIC System models of the
responsible entity’s planning area for performing the study or studies needed to complete benchmark and supplemental
GMD Vulnerability Assessment(s). [Violation Risk Factor: High] [Time Horizon: Long-term Planning]
M2. Each responsible entity, as determined in Requirement R1, shall have evidence in either electronic or hard copy format that
it is maintaining System models and GIC System models of the responsible entity’s planning area for performing the study
or studies needed to complete benchmark and supplemental GMD Vulnerability Assessment(s).
R3. Each responsible entity, as determined in Requirement R1, shall have criteria for acceptable System steady state voltage
performance for its System during the benchmark GMD events described in Attachment 1. [Violation Risk Factor: Medium]
[Time Horizon: Long-term Planning]
M3. Each responsible entity, as determined in Requirement R1, shall have evidence, such as electronic or hard copies of the
criteria for acceptable System steady state voltage performance for its System in accordance with Requirement R3.
Benchmark GMD Vulnerability Assessment(s)
Draft 2 of TPL-007-2
October 2017
Page 4 of 48
TPL-007-1 2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
R4. Each responsible entity, as determined in Requirement R1, shall complete a benchmark GMD Vulnerability Assessment of
the Near-Term Transmission Planning Horizon at least once every 60 calendar months. This benchmark GMD Vulnerability
Assessment shall use a study or studies based on models identified in Requirement R2, document assumptions, and
document summarized results of the steady state analysis. [Violation Risk Factor: High] [Time Horizon: Long-term Planning]
4.1. The study or studies shall include the following conditions:
4.1.1. System On-Peak Load for at least one year within the Near-Term Transmission Planning Horizon; and
4.1.2. System Off-Peak Load for at least one year within the Near-Term Transmission Planning Horizon.
4.2. The study or studies shall be conducted based on the benchmark GMD event described in Attachment 1 to determine
whether the System meets the performance requirements for the steady state planning benchmark GMD event
contained in Table 1.
4.3. The benchmark GMD Vulnerability Assessment shall be provided within 90 calendar days of completion: (i) to the
responsible entity’s Reliability Coordinator, adjacent Planning Coordinators, and adjacent Transmission Planners, and
within 90 calendar days of completion, and (ii) to any functional entity that submits a written request and has a
reliability-related need within 90 calendar days of receipt of such request or within 90 calendar days of completion of
the benchmark GMD Vulnerability Assessment, whichever is later.
4.3.1. If a recipient of the benchmark GMD Vulnerability Assessment provides documented comments on the
results, the responsible entity shall provide a documented response to that recipient within 90 calendar days
of receipt of those comments.
Draft 2 of TPL-007-2
October 2017
Page 5 of 48
TPL-007-1 2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
M4. Each responsible entity, as determined in Requirement R1, shall have dated evidence such as electronic or hard copies of
its benchmark GMD Vulnerability Assessment meeting all of the requirements in Requirement R4. Each responsible entity,
as determined in Requirement R1, shall also provide evidence, such as email records, web postings with an electronic
notice of posting, or postal receipts showing recipient and date, that it has distributed its benchmark GMD Vulnerability
Assessment within 90 calendar days of completion: (i) to its the responsible entity’s Reliability Coordinator, adjacent
Planning Coordinator(s), and adjacent Transmission Planner(s) within 90 calendar days of completion, and (ii) to any
functional entity who has submittedthat submits a written request and has a reliability-related need within 90 calendar
days of receipt of such request or within 90 calendar days of completion of the benchmark GMD Vulnerability Assessment,
whichever is later, as specified in Requirement R4. Each responsible entity, as determined in Requirement R1, shall also
provide evidence, such as email notices or postal receipts showing recipient and date, that it has provided a documented
response to comments received on its benchmark GMD Vulnerability Assessment within 90 calendar days of receipt of
those comments in accordance with Requirement R4.
R5. Each responsible entity, as determined in Requirement R1, shall provide GIC flow information to be used for the
benchmark transformer thermal impact assessment of transformers specified in Requirement R6 to each Transmission
Owner and Generator Owner that owns an applicable Bulk Electric System (BES) power transformer in the planning area.
The GIC flow information shall include: [Violation Risk Factor: Medium] [Time Horizon: Long-term Planning]
5.1. The maximum effective GIC value for the worst case geoelectric field orientation for the benchmark GMD event
described in Attachment 1. This value shall be provided to the Transmission Owner or Generator Owner that owns
each applicable BES power transformer in the planning area.
5.2. The effective GIC time series, GIC(t), calculated using the benchmark GMD event described in Attachment 1 in
response to a written request from the Transmission Owner or Generator Owner that owns an applicable BES power
transformer in the planning area. GIC(t) shall be provided within 90 calendar days of receipt of the written request
and after determination of the maximum effective GIC value in Part 5.1.
M5. Each responsible entity, as determined in Requirement R1, shall provide evidence, such as email records, web postings with
an electronic notice of posting, or postal receipts showing recipient and date, that it has provided the maximum effective
GIC values to the Transmission Owner and Generator Owner that owns each applicable BES power transformer in the
planning area as specified in Requirement R5, Part 5.1. Each responsible entity, as determined in Requirement R1, shall also
provide evidence, such as email records, web postings with an electronic notice of posting, or postal receipts showing
recipient and date, that it has provided GIC(t) in response to a written request from the Transmission Owner or Generator
Owner that owns an applicable BES power transformer in the planning area.
Draft 2 of TPL-007-2
October 2017
Page 6 of 48
TPL-007-1 2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
R6. Each Transmission Owner and Generator Owner shall conduct a benchmark thermal impact assessment for its solely and
jointly owned applicable BES power transformers where the maximum effective GIC value provided in Requirement R5,
Part 5.1, is 75 A per phase or greater. The benchmark thermal impact assessment shall: [Violation Risk Factor: Medium]
[Time Horizon: Long-term Planning]
6.1. Be based on the effective GIC flow information provided in Requirement R5;
6.2. Document assumptions used in the analysis;
6.3. Describe suggested actions and supporting analysis to mitigate the impact of GICs, if any; and
6.4. Be performed and provided to the responsible entities, as determined in Requirement R1, within 24 calendar months
of receiving GIC flow information specified in Requirement R5, Part 5.1.
M6. Each Transmission Owner and Generator Owner shall have evidence such as electronic or hard copies of its benchmark
thermal impact assessment for all of its solely and jointly owned applicable BES power transformers where the maximum
effective GIC value provided in Requirement R5, Part 5.1, is 75 A per phase or greater, and shall have evidence such as
email records, web postings with an electronic notice of posting, or postal receipts showing recipient and date, that it has
provided its thermal impact assessment to the responsible entities as specified in Requirement R6.
Rationale for Requirement R7: The proposed requirement addresses directives in Order
No. 830 for establishing Corrective Action Plan (CAP) deadlines associated with GMD
Vulnerability Assessments. In Order No. 830, FERC directed revisions to TPL-007 such that
CAPs are developed within one year from the completion of GMD Vulnerability
Assessments (P 101). Furthermore, FERC directed establishment of implementation
deadlines after the completion of the CAP as follows (P 102):
•
Two years for non-hardware mitigation; and
•
Four years for hardware mitigation.
The objective of Part 7.4 is to provide awareness to potentially impacted entities when
implementation of planned mitigation is not achievable within the deadlines established
in Part 7.3. Examples of situations beyond the control of the of the responsible entity (see
Section 7.4) include, but are not limited to:
Draft 2 of TPL-007-2
October 2017
Page 7 of 48
TPL-007-1 2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
•
Delays resulting from regulatory/legal processes, such as permitting;
•
Delays resulting from stakeholder processes required by tariff;
•
Delays resulting from equipment lead times; or
•
Delays resulting from the inability to acquire necessary Right-of-Way.
R7. Each responsible entity, as determined in Requirement R1, that concludes, through the benchmark GMD Vulnerability
Assessment conducted in Requirement R4, that their System does not meet the performance requirements for the steady
state planning benchmark GMD event contained in of Table 1, shall develop a Corrective Action Plan (CAP) addressing how
the performance requirements will be met. The Corrective Action Plan CAP shall: [Violation Risk Factor: High] [Time
Horizon: Long-term Planning]
7.1. List System deficiencies and the associated actions needed to achieve required System performance. Examples of
such actions include:
•
Installation, modification, retirement, or removal of Transmission and generation Facilities and any associated
equipment.
•
Installation, modification, or removal of Protection Systems or Remedial Action SchemesSpecial Protection
Systems.
•
Use of Operating Procedures, specifying how long they will be needed as part of the Corrective Action PlanCAP.
•
Use of Demand-Side Management, new technologies, or other initiatives.
7.2. Be developed within one year of completion of the benchmark reviewed in subsequent GMD Vulnerability
Assessments until it is determined that the System meets the performance requirements contained in Table 1.
7.3. Be provided within 90 calendar days of completion to the responsible entity’s Reliability Coordinator, adjacent
Planning Coordinator(s), adjacent Transmission Planner(s), functional entities referenced in the Corrective Action
Plan, and any functional entity that submits a written request and has a reliability-related need. Include a timetable,
subject to revision by the responsible entity in Part 7.4, for implementing the selected actions from Part 7.1. The
timetable shall:
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7.3.1. If a recipient of the Corrective Action Plan provides documented comments on the results, the responsible
entity shall provide a documented response to that recipient within 90 calendar days of receipt of those
comments. Specify implementation of non-hardware mitigation, if any, within two years of development of
the CAP; and
7.3.1.7.3.2.
Specify implementation of hardware mitigation, if any, within four years of development of the CAP.
7.4. Be revised if situations beyond the control of the responsible entity determined in Requirement R1 prevent
implementation of the CAP within the timetable for implementation provided in Part 7.3. The revised CAP shall
document the following, and be updated at least once every 12 calendar months until implemented:
7.4.1. Circumstances causing the delay for fully or partially implementing the selected actions in Part 7.1;
7.4.2. Description of the original CAP, and any previous changes to the CAP, with the associated timetable(s) for
implementing the selected actions in Part 7.1; and
7.4.3. Revisions to the selected actions in Part 7.1, if any, including utilization of Operating Procedures if applicable,
and the updated timetable for implementing the selected actions.
7.4.7.5.
Be provided within 90 calendar days of completion: (i) to the responsible entity’s Reliability Coordinator,
adjacent Planning Coordinator(s), adjacent Transmission Planner(s), and functional entities referenced in the
Corrective Action Plan, andCAP within 90 calendar days of development or revision, and (ii) to any functional entity
that submits a written request and has a reliability-related need within 90 calendar days of receipt of such request or
within 90 calendar days of development or revision, whichever is later.
7.4.1.7.5.1. If a recipient of the Corrective Action PlanCAP provides documented comments on the results, the
responsible entity shall provide a documented response to that recipient within 90 calendar days of receipt of
those comments.
M7. Each responsible entity, as determined in Requirement R1, that concludes, through the benchmark GMD Vulnerability
Assessment conducted in Requirement R4, that the responsible entity’s System does not meet the performance
requirements for the steady state planning benchmark GMD event contained in of Table 1 shall have evidence such as
dated electronic or hard copies of its CAP Corrective Action Plan including timetable for implementing selected actions, as
specified in Requirement R7. Each responsible entity, as determined in Requirement R1, shall also provide evidence, such
as email records or postal receipts showing recipient and date, that it has revised its CAP if situations beyond the
responsible entity's control prevent implementation of the CAP within the timetable specified. Each responsible entity, as
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determined in Requirement R1, shall also provide evidence, such as email records, web postings with an electronic notice
of posting, or postal receipts showing recipient and date, that it has distributed its CAP Corrective Action Plan or relevant
information, if any, (i) to the responsible entity’s Reliability Coordinator, adjacent Planning Coordinator(s), adjacent
Transmission Planner(s), and functional entities referenced in the Corrective Action Plan CAP within 90 calendar days of
development or revision, and (ii) to any functional entity that submits a written request and has a reliability-related need,
within 90 calendar days of receipt of such request or within 90 calendar days of development or revision, whichever is later
as specified in Requirement R7. Each responsible entity, as determined in Requirement R1, shall also provide evidence,
such as email notices or postal receipts showing recipient and date, that it has provided a documented response to
comments received on its CAP Corrective Action Plan within 90 calendar days of receipt of those comments, in accordance
with Requirement R7.
Supplemental GMD Vulnerability Assessment(s)
Rationale for Requirements R8 – R10: The proposed requirements address directives in
Order No. 830 for revising the benchmark GMD event used in GMD Vulnerability
Assessments (P 44, P 47-49). The requirements add a supplemental GMD Vulnerability
Assessment based on the supplemental GMD event that accounts for localized peak
geoelectric fields.
R8.
Each responsible entity, as determined in Requirement R1, shall complete a supplemental GMD Vulnerability Assessment
of the Near-Term Transmission Planning Horizon at least once every 60 calendar months. This supplemental GMD
Vulnerability Assessment shall use a study or studies based on models identified in Requirement R2, document
assumptions, and document summarized results of the steady state analysis. [Violation Risk Factor: High] [Time Horizon:
Long-term Planning]
8.1. The study or studies shall include the following conditions:
8.1.1. System On-Peak Load for at least one year within the Near-Term Transmission Planning Horizon; and
8.1.2. System Off-Peak Load for at least one year within the Near-Term Transmission Planning Horizon.
8.2. The study or studies shall be conducted based on the supplemental GMD event described in Attachment 1 to
determine whether the System meets the performance requirements for the steady state planning supplemental
GMD event contained in Table 1.
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8.3. If the analysis concludes there is Cascading caused by the supplemental GMD event described in Attachment 1, an
evaluation of possible actions designed to reduce the likelihood or mitigate the consequences and adverse impacts of
the event(s) shall be conducted.
8.4. The supplemental GMD Vulnerability Assessment shall be provided: (i) to the responsible entity’s Reliability
Coordinator, adjacent Planning Coordinators, adjacent Transmission Planners within 90 calendar days of completion,
and (ii) to any functional entity that submits a written request and has a reliability-related need within 90 calendar
days of receipt of such request or within 90 calendar days of completion of the supplemental GMD Vulnerability
Assessment, whichever is later.
8.4.1. If a recipient of the supplemental GMD Vulnerability Assessment provides documented comments on the
results, the responsible entity shall provide a documented response to that recipient within 90 calendar days
of receipt of those comments.
M8. Each responsible entity, as determined in Requirement R1, shall have dated evidence such as electronic or hard copies of
its supplemental GMD Vulnerability Assessment meeting all of the requirements in Requirement R8. Each responsible
entity, as determined in Requirement R1, shall also provide evidence, such as email records, web postings with an
electronic notice of posting, or postal receipts showing recipient and date, that it has distributed its supplemental GMD
Vulnerability: (i) to the responsible entity’s Reliability Coordinator, adjacent Planning Coordinators, adjacent Transmission
Planners within 90 calendar days of completion, and (ii) to any functional entity that submits a written request and has a
reliability-related need within 90 calendar days of receipt of such request or within 90 calendar days of completion of the
supplemental GMD Vulnerability Assessment, whichever is later, as specified in Requirement R8. Each responsible entity,
as determined in Requirement R1, shall also provide evidence, such as email notices or postal receipts showing recipient
and date, that it has provided a documented response to comments received on its supplemental GMD Vulnerability
Assessment within 90 calendar days of receipt of those comments in accordance with Requirement R8.
R9.
Each responsible entity, as determined in Requirement R1, shall provide GIC flow information to be used for the
supplemental thermal impact assessment of transformers specified in Requirement R10 to each Transmission Owner and
Generator Owner that owns an applicable Bulk Electric System (BES) power transformer in the planning area. The GIC flow
information shall include: [Violation Risk Factor: Medium] [Time Horizon: Long-term Planning]
9.1. The maximum effective GIC value for the worst case geoelectric field orientation for the supplemental GMD event
described in Attachment 1. This value shall be provided to the Transmission Owner or Generator Owner that owns
each applicable BES power transformer in the planning area.
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9.2. The effective GIC time series, GIC(t), calculated using the supplemental GMD event described in Attachment 1 in
response to a written request from the Transmission Owner or Generator Owner that owns an applicable BES power
transformer in the planning area. GIC(t) shall be provided within 90 calendar days of receipt of the written request
and after determination of the maximum effective GIC value in Part 9.1.
M9. Each responsible entity, as determined in Requirement R1, shall provide evidence, such as email records, web postings
with an electronic notice of posting, or postal receipts showing recipient and date, that it has provided the maximum
effective GIC values to the Transmission Owner and Generator Owner that owns each applicable BES power transformer in
the planning area as specified in Requirement R9, Part 9.1. Each responsible entity, as determined in Requirement R1, shall
also provide evidence, such as email records, web postings with an electronic notice of posting, or postal receipts showing
recipient and date, that it has provided GIC(t) in response to a written request from the Transmission Owner or Generator
Owner that owns an applicable BES power transformer in the planning area.
R10. Each Transmission Owner and Generator Owner shall conduct a supplemental thermal impact assessment for its solely and
jointly owned applicable BES power transformers where the maximum effective GIC value provided in Requirement R9,
Part 9.1, is 85 A per phase or greater. The supplemental thermal impact assessment shall: [Violation Risk Factor: Medium]
[Time Horizon: Long-term Planning]
10.1. Be based on the effective GIC flow information provided in Requirement R9;
10.2. Document assumptions used in the analysis;
10.3. Describe suggested actions and supporting analysis to mitigate the impact of GICs, if any; and
10.4. Be performed and provided to the responsible entities, as determined in Requirement R1, within 24 calendar months
of receiving GIC flow information specified in Requirement R9, Part 9.1.
M10. Each Transmission Owner and Generator Owner shall have evidence such as electronic or hard copies of its supplemental
thermal impact assessment for all of its solely and jointly owned applicable BES power transformers where the maximum
effective GIC value provided in Requirement R9, Part 9.1, is 85 A per phase or greater, and shall have evidence such as
email records, web postings with an electronic notice of posting, or postal receipts showing recipient and date, that it has
provided its supplemental thermal impact assessment to the responsible entities as specified in Requirement R10.
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GMD Measurement Data Processes
Rationale for Requirements R11 and R12: The proposed requirements address directives
in Order No. 830 for requiring responsible entities to collect GIC monitoring and
magnetometer data as necessary to enable model validation and situational awareness (P
88; P. 90-92). GMD measurement data refers to GIC monitor data and geomagnetic field
data in Requirements R11 and R12, respectively. See the Guidelines and Technical Basis
section of this standard for technical information.
The objective of Requirement R11 is for entities to obtain GIC data for the Planning
Coordinator's planning area or other part of the system included in the Planning
Coordinator's GIC System model to inform GMD Vulnerability Assessments. Technical
considerations for GIC monitoring are contained in Chapter 9 of the 2012 Special
Reliability Assessment Interim Report: Effects of Geomagnetic Disturbances on the BulkPower System (NERC 2012 GMD Report). GIC monitoring is generally performed by Hall
effect transducers that are attached to the neutral of the transformer and measure dc
current flowing through the neutral.
The objective of Requirement R12 is for entities to obtain geomagnetic field data for the
Planning Coordinator's planning area to inform GMD Vulnerability Assessments.
Magnetometers provide geomagnetic field data by measuring changes in the earth's
magnetic field. Sources of geomagnetic field data include:
•
Observatories such as those operated by U.S. Geological Survey, Natural
Resources Canada, research organizations, or university research facilities;
•
Installed magnetometers; and
•
Commercial or third-party sources of geomagnetic field data.
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Geomagnetic field data for a Planning Coordinator’s planning area is obtained from one
or more of the above data sources located in the Planning Coordinator’s planning area, or
by obtaining a geomagnetic field data product for the Planning Coordinator’s planning
area from a government or research organization. The geomagnetic field data product
does not need to be derived from a magnetometer or observatory within the Planning
Coordinator’s planning area.
R11. Each responsible entity, as determined in Requirement R1, shall implement a process to obtain GIC monitor data from at
least one GIC monitor located in the Planning Coordinator's planning area or other part of the system included in the
Planning Coordinator's GIC System model. [Violation Risk Factor: Lower] [Time Horizon: Long-term Planning]
M11. Each responsible entity, as determined in Requirement R1, shall have evidence such as electronic or hard copies of its GIC
monitor location(s) and documentation of its process to obtain GIC monitor data in accordance with Requirement R11.
R12. Each responsible entity, as determined in Requirement R1, shall implement a process to obtain geomagnetic field data for
its Planning Coordinator’s planning area. [Violation Risk Factor: Lower] [Time Horizon: Long-term Planning]
M8.M12. Each responsible entity, as determined in Requirement R1, shall have evidence such as electronic or hard copies of its
process to obtain geomagnetic field data for its Planning Coordinator’s planning area in accordance with Requirement R12.
C. Compliance
1.
Compliance Monitoring Process
1.1. Compliance Enforcement Authority: “As defined in the NERC Rules of Procedure,: “Compliance Enforcement
Authority” means NERC or the Regional Entity, or any entity as otherwise designated by an Applicable
Governmental Authority, in their respective roles of monitoring and/or enforcing compliance with the
NERCmandatory and enforceable Reliability Standards in their respective jurisdictions.
1.2. Evidence Retention: The following evidence retention periodsperiod(s) identify the period of time an entity is
required to retain specific evidence to demonstrate compliance. For instances where the evidence retention
period specified below is shorter than the time since the last audit, the CEACompliance Enforcement Authority
may ask an entity to provide other evidence to show that it was compliant for the full-time period since the last
audit.
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TPL-007-1 2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
The Planning Coordinator, Transmission Planner, Transmission Owner, and Generator OwnerThe applicable
entity shall keep data or evidence to show compliance as identified below unless directed by its Compliance
Enforcement Authority to retain specific evidence for a longer period of time as part of an investigation:.
•
For Requirements R1, R2, R3, R5, R6, R9, and R6R10, each responsible entity shall retain documentation as
evidence for five years.
•
For Requirements R4 and R8, each responsible entity shall retain documentation of the current GMD
Vulnerability Assessment and the preceding GMD Vulnerability Assessment.
•
For Requirement R7, each responsible entity shall retain documentation as evidence for five years or until
all actions in the Corrective Action Plan are completed, whichever is later.
•
For Requirements R11 and R12, each responsible entity shall retain documentation as evidence for three
years.
1.3. Compliance Monitoring and Enforcement Program: As defined in the NERC Rules of Procedure, “Compliance
Monitoring and Enforcement Program” refers to the identification of the processes that will be used to evaluate
data or information for the purpose of assessing performance or outcomes with the associated Reliability
Standard.
Compliance Audits
Self-Certifications
Spot Checking
Compliance Investigations
Self-Reporting
Complaints
1.4. Additional Compliance Information
None
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Table 1 –: Steady State Planning EventsGMD Event
Steady State:
a. Voltage collapse, Cascading and uncontrolled islanding shall not occur.
b. Generation loss is acceptable as a consequence of the steady state planning event. GMD events.
c. Planned System adjustments such as Transmission configuration changes and re-dispatch of generation are allowed if such
adjustments are executable within the time duration applicable to the Facility Ratings.
Event
Interruption of
Firm
Transmission
Service Allowed
Load Loss
Allowed
Category
Initial Condition
Benchmark GMD
Event - GMD Event
with Outages
1. System as may be
postured in response
to space weather
information1, and then
2. GMD event2
Reactive Power compensation devices
and other Transmission Facilities
removed as a result of Protection
System operation or Misoperation due
to harmonics during the GMD event
Yes3
Yes3
Supplemental
GMD Event - GMD
Event with
Outages
1. System as may be
postured in response
to space weather
information1, and then
2. GMD event2
Reactive Power compensation devices
and other Transmission Facilities
removed as a result of Protection
System operation or Misoperation due
to harmonics during the GMD event
Yes
Yes
Table 1 –: Steady State Performance Footnotes
1. The System condition for GMD planning may include adjustments to posture the System that are executable in response to
space weather information.
2. The GMD conditions for the benchmark and supplemental planning eventevents are described in Attachment 1 (Benchmark GMD
Event). .
3. Load loss as a result of manual or automatic Load shedding (e.g.., UVLS) and/or curtailment of Firm Transmission Service may
be used to meet BES performance requirements during studied GMD conditions. The likelihood and magnitude of Load loss or
curtailment of Firm Transmission Service should be minimized.
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Violation Severity Levels
R#
Time
Horizon
Violation Severity Levels
VRF
Lower VSL
Moderate VSL
High VSL
Severe VSL
N/A
The Planning
Coordinator, in
conjunction with its
Transmission
Planner(s), failed to
determine and identify
individual or joint
responsibilities of the
Planning Coordinator
and Transmission
Planner(s) in the
Planning Coordinator’s
planning area for
maintaining models,
and performing the
study or studies needed
to complete benchmark
and supplemental GMD
Vulnerability
Assessment(s), and
implementing
process(es) to obtain
GMD measurement
data as specified in this
standard.
LongLower
term
Planning
R1.
Draft 2 of TPL-007-2
October 2017
N/A
N/A
Page 17 of 48
TPL-007-1 2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
R#
Time
Horizon
Violation Severity Levels
VRF
Lower VSL
Moderate VSL
High VSL
Severe VSL
N/A
The responsible entity
did not maintain either
System models or GIC
System models of the
responsible entity’s
planning area for
performing the study or
studies needed to
complete benchmark
and supplemental GMD
Vulnerability
Assessment(s).
The responsible entity
did not maintain both
System models and GIC
System models of the
responsible entity’s
planning area for
performing the study or
studies needed to
complete benchmark
and supplemental GMD
Vulnerability
Assessment(s).
N/A
The responsible entity
did not have criteria for
acceptable System
steady state voltage
performance for its
System during the
benchmark GMD events
described in
Attachment 1 as
required.
LongHigh
term
Planning
R2.
N/A
LongMedium
term
Planning
R3.
Draft 2 of TPL-007-2
October 2017
N/A
N/A
Page 18 of 48
TPL-007-1 2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
R#
Time
Horizon
LongHigh
term
Planning
R4.
Draft 2 of TPL-007-2
October 2017
Violation Severity Levels
VRF
Lower VSL
Moderate VSL
High VSL
Severe VSL
The responsible
entity completed a
benchmark GMD
Vulnerability
Assessment, but it
was more than 60
calendar months and
less than or equal to
64 calendar months
since the last
benchmark GMD
Vulnerability
Assessment.
The responsible
entity's completed
benchmark GMD
Vulnerability
Assessment failed to
satisfy one of the
elements listed in
Requirement R4, Parts
4.1 through 4.3;
OR
The responsible entity
completed a
benchmark GMD
Vulnerability
Assessment, but it was
more than 64 calendar
months and less than
or equal to 68 calendar
months since the last
benchmark GMD
Vulnerability
Assessment.
The responsible entity's
completed benchmark
GMD Vulnerability
Assessment failed to
satisfy two of the
elements listed in
Requirement R4, Parts
4.1 through 4.3;
OR
The responsible entity
completed a benchmark
GMD Vulnerability
Assessment, but it was
more than 68 calendar
months and less than or
equal to 72 calendar
months since the last
benchmark GMD
Vulnerability
Assessment.
The responsible entity's
completed benchmark
GMD Vulnerability
Assessment failed to
satisfy three of the
elements listed in
Requirement R4, Parts
4.1 through 4.3;
OR
The responsible entity
completed a benchmark
GMD Vulnerability
Assessment, but it was
more than 72 calendar
months since the last
benchmark GMD
Vulnerability
Assessment;
OR
The responsible entity
does not have a
completed benchmark
GMD Vulnerability
Assessment.
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TPL-007-1 2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
R#
Time
Horizon
LongMedium
term
Planning
R5.
Draft 2 of TPL-007-2
October 2017
Violation Severity Levels
VRF
Lower VSL
Moderate VSL
High VSL
Severe VSL
The responsible
entity provided the
effective GIC time
series, GIC(t), in
response to written
request, but did so
more than 90
calendar days and
less than or equal to
100 calendar days
after receipt of a
written request.
The responsible entity
provided the effective
GIC time series, GIC(t),
in response to written
request, but did so
more than 100
calendar days and less
than or equal to 110
calendar days after
receipt of a written
request.
The responsible entity
provided the effective
GIC time series, GIC(t),
in response to written
request, but did so
more than 110 calendar
days after receipt of a
written request.
The responsible entity
did not provide the
maximum effective GIC
value to the
Transmission Owner
and Generator Owner
that owns each
applicable BES power
transformer in the
planning area;
OR
The responsible entity
did not provide the
effective GIC time
series, GIC(t), upon
written request.
Page 20 of 48
TPL-007-1 2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
LongMedium
term
Planning
R6.
Draft 2 of TPL-007-2
October 2017
The responsible
entity failed to
conduct a
benchmark thermal
impact assessment
for 5% or less or one
of its solely owned
and jointly owned
applicable BES power
transformers
(whichever is
greater) where the
maximum effective
GIC value provided in
Requirement R5, Part
5.1, is 75 A or greater
per phase;
OR
The responsible
entity conducted a
benchmark thermal
impact assessment
for its solely owned
and jointly owned
applicable BES power
transformers where
the maximum
effective GIC value
provided in
Requirement R5, Part
The responsible entity
failed to conduct a
benchmark thermal
impact assessment for
more than 5% up to
(and including) 10% or
two of its solely owned
and jointly owned
applicable BES power
transformers
(whichever is greater)
where the maximum
effective GIC value
provided in
Requirement R5, Part
5.1, is 75 A or greater
per phase;
OR
The responsible entity
conducted a
benchmark thermal
impact assessment for
its solely owned and
jointly owned
applicable BES power
transformers where
the maximum effective
GIC value provided in
Requirement R5, Part
5.1, is 75 A or greater
The responsible entity
failed to conduct a
benchmark thermal
impact assessment for
more than 10% up to
(and including) 15% or
three of its solely
owned and jointly
owned applicable BES
power transformers
(whichever is greater)
where the maximum
effective GIC value
provided in
Requirement R5, Part
5.1, is 75 A or greater
per phase;
OR
The responsible entity
conducted a benchmark
thermal impact
assessment for its solely
owned and jointly
owned applicable BES
power transformers
where the maximum
effective GIC value
provided in
Requirement R5, Part
5.1, is 75 A or greater
The responsible entity
failed to conduct a
benchmark thermal
impact assessment for
more than 15% or more
than three of its solely
owned and jointly
owned applicable BES
power transformers
(whichever is greater)
where the maximum
effective GIC value
provided in
Requirement R5, Part
5.1, is 75 A or greater
per phase;
OR
The responsible entity
conducted a benchmark
thermal impact
assessment for its solely
owned and jointly
owned applicable BES
power transformers
where the maximum
effective GIC value
provided in
Requirement R5, Part
5.1, is 75 A or greater
per phase but did so
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R#
Time
Horizon
Draft 2 of TPL-007-2
October 2017
Violation Severity Levels
VRF
Lower VSL
Moderate VSL
High VSL
Severe VSL
5.1, is 75 A or greater
per phase but did so
more than 24
calendar months and
less than or equal to
26 calendar months
of receiving GIC flow
information specified
in Requirement R5,
Part 5.1.
per phase but did so
more than 26 calendar
months and less than
or equal to 28 calendar
months of receiving
GIC flow information
specified in
Requirement R5, Part
5.1;
OR
The responsible entity
failed to include one of
the required elements
as listed in
Requirement R6, Parts
6.1 through 6.3.
per phase but did so
more than 28 calendar
months and less than or
equal to 30 calendar
months of receiving GIC
flow information
specified in
Requirement R5, Part
5.1;
OR
The responsible entity
failed to include two of
the required elements
as listed in Requirement
R6, Parts 6.1 through
6.3.
more than 30 calendar
months of receiving GIC
flow information
specified in
Requirement R5, Part
5.1;
OR
The responsible entity
failed to include three
of the required
elements as listed in
Requirement R6, Parts
6.1 through 6.3.
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TPL-007-1 2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
R#
Time
Horizon
LongHigh
term
Planning
R7.
Draft 2 of TPL-007-2
October 2017
Violation Severity Levels
VRF
Lower VSL
Moderate VSL
High VSL
Severe VSL
N/A The responsible
entity's Corrective
Action Plan failed to
comply with one of
the elements in
Requirement R7,
Parts 7.1 through 7.5.
The responsible
entity's Corrective
Action Plan failed to
comply with one two
of the elements in
Requirement R7, Parts
7.1 through 7.35.
The responsible entity's
Corrective Action Plan
failed to comply with
two three of the
elements in
Requirement R7, Parts
7.1 through 7.35.
The responsible entity's
Corrective Action Plan
failed to comply with
four or moreall three of
the elements in
Requirement R7, Parts
7.1 through 7.35;
OR
The responsible entity
did not have a
Corrective Action Plan
as required by
Requirement R7.
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R#
Time
Horizon
R8.
Draft 2 of TPL-007-2
October 2017
Violation Severity Levels
VRF
Lower VSL
Moderate VSL
High VSL
Severe VSL
The responsible
entity completed a
supplemental GMD
Vulnerability
Assessment, but it
was more than 60
calendar months and
less than or equal to
64 calendar months
since the last
supplemental GMD
Vulnerability
Assessment.
OR
The responsible
entity's completed
supplemental GMD
Vulnerability
Assessment failed to
satisfy one of
elements listed in
Requirement R8,
Parts 8.1 through
8.4;
The responsible
entity's completed
supplemental GMD
Vulnerability
Assessment failed to
satisfy two of elements
listed in Requirement
R8, Parts 8.1 through
8.4;
OR
The responsible entity
completed a
supplemental GMD
Vulnerability
Assessment, but it was
more than 64 calendar
months and less than
or equal to 68 calendar
months since the last
supplemental GMD
Vulnerability
Assessment.
The responsible entity's
completed
supplemental GMD
Vulnerability
Assessment failed to
satisfy three of the
elements listed in
Requirement R8, Parts
8.1 through 8.4;
OR
The responsible entity
completed a
supplemental GMD
Vulnerability
Assessment, but it was
more than 68 calendar
months and less than or
equal to 72 calendar
months since the last
supplemental GMD
Vulnerability
Assessment.
The responsible entity's
completed
supplemental GMD
Vulnerability
Assessment failed to
satisfy four of the
elements listed in
Requirement R8, Parts
8.1 through 8.4;
OR
The responsible entity
completed a
supplemental GMD
Vulnerability
Assessment, but it was
more than 72 calendar
months since the last
supplemental GMD
Vulnerability
Assessment;
OR
The responsible entity
does not have a
completed
supplemental GMD
Vulnerability
Assessment.
Page 24 of 48
TPL-007-1 2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
R#
Time
Horizon
R9.
Draft 2 of TPL-007-2
October 2017
Violation Severity Levels
VRF
Lower VSL
Moderate VSL
High VSL
Severe VSL
The responsible
entity provided the
effective GIC time
series, GIC(t), in
response to written
request, but did so
more than 90
calendar days and
less than or equal to
100 calendar days
after receipt of a
written request.
The responsible entity
provided the effective
GIC time series, GIC(t),
in response to written
request, but did so
more than 100
calendar days and less
than or equal to 110
calendar days after
receipt of a written
request.
The responsible entity
provided the effective
GIC time series, GIC(t),
in response to written
request, but did so
more than 110 calendar
days after receipt of a
written request.
The responsible entity
did not provide the
maximum effective GIC
value to the
Transmission Owner
and Generator Owner
that owns each
applicable BES power
transformer in the
planning area;
OR
The responsible entity
did not provide the
effective GIC time
series, GIC(t), upon
written request.
Page 25 of 48
TPL-007-1 2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
R10.
Draft 2 of TPL-007-2
October 2017
The responsible
entity failed to
conduct a
supplemental
thermal impact
assessment for 5% or
less or one of its
solely owned and
jointly owned
applicable BES power
transformers
(whichever is
greater) where the
maximum effective
GIC value provided in
Requirement R9, Part
9.1, is 85 A or greater
per phase;
OR
The responsible
entity conducted a
supplemental
thermal impact
assessment for its
solely owned and
jointly owned
applicable BES power
transformers where
the maximum
effective GIC value
The responsible entity
failed to conduct a
supplemental thermal
impact assessment for
more than 5% up to
(and including) 10% or
two of its solely owned
and jointly owned
applicable BES power
transformers
(whichever is greater)
where the maximum
effective GIC value
provided in
Requirement R9, Part
9.1, is 85 A or greater
per phase;
OR
The responsible entity
conducted a
supplemental thermal
impact assessment for
its solely owned and
jointly owned
applicable BES power
transformers where
the maximum effective
GIC value provided in
Requirement R9, Part
9.1, is 85 A or greater
The responsible entity
failed to conduct a
supplemental thermal
impact assessment for
more than 10% up to
(and including) 15% or
three of its solely
owned and jointly
owned applicable BES
power transformers
(whichever is greater)
where the maximum
effective GIC value
provided in
Requirement R9, Part
9.1, is 85 A or greater
per phase;
OR
The responsible entity
conducted a
supplemental thermal
impact assessment for
its solely owned and
jointly owned
applicable BES power
transformers where the
maximum effective GIC
value provided in
Requirement R9, Part
9.1, is 85 A or greater
The responsible entity
failed to conduct a
supplemental thermal
impact assessment for
more than 15% or more
than three of its solely
owned and jointly
owned applicable BES
power transformers
(whichever is greater)
where the maximum
effective GIC value
provided in
Requirement R9, Part
9.1, is 85 A or greater
per phase;
OR
The responsible entity
conducted a
supplemental thermal
impact assessment for
its solely owned and
jointly owned
applicable BES power
transformers where the
maximum effective GIC
value provided in
Requirement R9, Part
9.1, is 85 A or greater
per phase but did so
Page 26 of 48
TPL-007-1 2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
R#
Time
Horizon
Draft 2 of TPL-007-2
October 2017
Violation Severity Levels
VRF
Lower VSL
Moderate VSL
High VSL
Severe VSL
provided in
Requirement R9, Part
9.1, is 85 A or greater
per phase but did so
more than 24
calendar months and
less than or equal to
26 calendar months
of receiving GIC flow
information specified
in Requirement R9,
Part 9.1.
per phase but did so
more than 26 calendar
months and less than
or equal to 28 calendar
months of receiving
GIC flow information
specified in
Requirement R9, Part
9.1
OR
The responsible entity
failed to include one of
the required elements
as listed in
Requirement R10,
Parts 10.1 through
10.3.
per phase but did so
more than 28 calendar
months and less than or
equal to 30 calendar
months of receiving GIC
flow information
specified in
Requirement R9, Part
9.1;
OR
The responsible entity
failed to include two of
the required elements
as listed in Requirement
R10, Parts 10.1 through
10.3.
more than 30 calendar
months of receiving GIC
flow information
specified in
Requirement R9, Part
9.1;
OR
The responsible entity
failed to include three
of the required
elements as listed in
Requirement R10, Parts
10.1 through 10.3.
Page 27 of 48
TPL-007-1 2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
R#
Time
Horizon
Violation Severity Levels
VRF
Lower VSL
R11.
R12.
N/A
N/A
Moderate VSL
N/A
N/A
High VSL
Severe VSL
N/A
The responsible entity
did not implement a
process to obtain GIC
monitor data from at
least one GIC monitor
located in the Planning
Coordinator’s planning
area or other part of
the system included in
the Planning
Coordinator’s GIC
System Model.
N/A
The responsible entity
did not implement a
process to obtain
geomagnetic field data
for its Planning
Coordinator’s planning
area.
C. Regional Variances
None.
D. Associated Documents
Attachment 1
Draft 2 of TPL-007-2
October 2017
Page 28 of 48
TPL-007-1 2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
Version History
Version
1
2
Draft 2 of TPL-007-2
October 2017
Date
Action
December 17,
Adopted by the NERC Board of Trustees
2014
TBD
Revised to respond to directives in FERC
Order No. 830.
Change
Tracking
New
Revised
Page 29 of 48
TPL-007-1 2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
Attachment 1
Calculating Geoelectric Fields for the Benchmark and Supplemental GMD Events
The benchmark GMD event 1 defines the geoelectric field values used to compute GIC flows that
are needed to conduct a benchmark GMD Vulnerability Assessment. It is composed of the
following elements: (1) a reference peak geoelectric field amplitude of 8 V/km derived from
statistical analysis of historical magnetometer data; (2) scaling factors to account for local
geomagnetic latitude; (3) scaling factors to account for local earth conductivity; and (4) a
reference geomagnetic field time series or waveshape waveform to facilitate time-domain
analysis of GMD impact on equipment.
The supplemental GMD event is composed of similar elements as described above, except (1) the
reference peak geoelectric field amplitude is 12 V/km over a localized area; and (2) the
geomagnetic field time series or waveform includes a local enhancement in the waveform.2
The regional geoelectric field peak amplitude used in GMD Vulnerability Assessment, Epeak, can
be obtained from the reference geoelectric field value of 8 V/km for the benchmark GMD event
(1) or 12 V/km for the supplemental GMD event (2) using the following relationships:
𝐸𝐸𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝 = 8 × 𝛼𝛼 × 𝛽𝛽 𝑏𝑏 (𝑉𝑉 ⁄𝑘𝑘𝑘𝑘)
𝐸𝐸𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝 = 12 × 𝛼𝛼 × 𝛽𝛽 𝑠𝑠 (𝑉𝑉 ⁄𝑘𝑘𝑘𝑘)
(1)
(2)
where, α is the scaling factor to account for local geomagnetic latitude, and β is a scaling factor
to account for the local earth conductivity structure. Subscripts b and s for the β scaling factor
denote association with the benchmark or supplemental GMD events, respectively.
Scaling the Geomagnetic Field
The benchmark and supplemental GMD events is are defined for geomagnetic latitude of 60° and
it must be scaled to account for regional differences based on geomagnetic latitude. Table 2
provides a scaling factor correlating peak geoelectric field to geomagnetic latitude. Alternatively,
the scaling factor α is computed with the empirical expression:
𝛼𝛼 = 0.001 × 𝑒𝑒 (0.115×𝐿𝐿)
(23)
where, L is the geomagnetic latitude in degrees and 0.1 ≤ α ≤ 1.
The benchmark Benchmark GMD Geomagnetic Disturbance event Event description Description, May 2016 is available on the
Related Information webProject 2013-03 Geomagnetic Disturbance Mitigation project page for TPL-007-1:
http://www.nerc.com/pa/Stand/TPL0071RD/Benchmark_clean_May12_complete.pdf.
2 The extent of local enhancements is on the order of 100 km in North-South (latitude) direction but longer in East-West
(longitude) direction. The local enhancement in the geomagnetic field occurs over the time period of 2-5 minutes. Additional
information is available in the Supplemental Geomagnetic Disturbance Event Description, October 2017 white paper on the
Project 2013-03 Geomagnetic Disturbance Mitigation project webpage: http://www.nerc.com/pa/Stand/Pages/Project-201303-Geomagnetic-Disturbance-Mitigation.aspx.
1
Draft 2 of TPL-007-2
October 2017
Page 30 of 48
TPL-007-1 2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
For large planning areas that cover more than one scaling factor from Table 2, the GMD
Vulnerability Assessment should be based on a peak geoelectric field that is:
•
calculated by using the most conservative (largest) value for α; or
•
calculated assuming a non-uniform or piecewise uniform geomagnetic field.
Table 2: –
Geomagnetic Field Scaling Factors for
the Benchmark and Supplemental GMD
Events
Geomagnetic Latitude
(Degrees)
Scaling Factor1
(α)
≤ 40
0.10
45
0.2
50
0.3
54
0.5
56
0.6
57
0.7
58
0.8
59
0.9
≥ 60
1.0
Scaling the Geoelectric Field
The benchmark GMD event is defined for the reference Quebec earth model described in Table
4. The peak geoelectric field, Epeak, used in a GMD Vulnerability Assessment may be obtained by
either:
•
Calculating the geoelectric field for the ground conductivity in the planning area and the
reference geomagnetic field time series scaled according to geomagnetic latitude, using
a procedure such as the plane wave method described in the NERC GMD Task Force GIC
Application Guide; 3 or
•
Using the earth conductivity scaling factor β from Table 3 that correlates to the ground
conductivity map in Figure 1 or Figure 2. Along with the scaling factor α from equation
(23) or Table 2, β is applied to the reference geoelectric field using equation (1 or 2, as
applicable) to obtain the regional geoelectric field peak amplitude Epeak to be used in
GMD Vulnerability Assessments. When a ground conductivity model is not available, the
planning entity should use the largest β factor of adjacent physiographic regions or a
technically justified value.
Available at the NERC GMD Task Force project webpage: http://www.nerc.com/comm/PC/Pages/Geomagnetic-DisturbanceTask-Force-(GMDTF)-2013.aspxhttp://www.nerc.com/comm/PC/Pages/Geomagnetic-Disturbance-Task-Force-(GMDTF)2013.aspx.
3
Draft 2 of TPL-007-2
October 2017
Page 31 of 48
TPL-007-1 2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
The earth models used to calculate Table 3 for the United States were obtained from publicly
available information published on the U. S. Geological Survey website. 4 The models used to
calculate Table 3 for Canada were obtained from Natural Resources Canada (NRCan) and reflect
the average structure for large regions. A planner can also use specific earth model(s) with
documented justification and the reference geomagnetic field time series to calculate the β
factor(s) as follows:
𝛽𝛽𝑏𝑏 = 𝐸𝐸 ⁄8 for the benchmark GMD event
(34)
𝛽𝛽𝑠𝑠 = 𝐸𝐸 ⁄12 for the supplemental GMD
(5)
where, E is the absolute value of peak geoelectric in V/km obtained from the technically justified
earth model and the reference geomagnetic field time series.
For large planning areas that span more than one β scaling factor, the most conservative (largest)
value for β may be used in determining the peak geoelectric field to obtain conservative results.
Alternatively, a planner could perform analysis using a non-uniform or piecewise uniform
geoelectric field.
Applying the Localized Peak Geoelectric Field in the Supplemental GMD Event
The peak geoelectric field of the supplemental GMD event occurs in a localized area.5 Planners
have flexibility to determine how to apply the localized peak geoelectric field over the planning
area in performing GIC calculations. Examples of approaches are:
•
Apply the peak geoelectric field (12 V/km scaled to the planning area) over the entire
planning area;
•
Apply a spatially limited (12 V/km scaled to the planning area) peak geoelectric field (e.g.,
100 km in North-South latitude direction and 500 km in East-West longitude direction)
over a portion(s) of the system, and apply the benchmark GMD event over the rest of the
system; or
•
Other methods to adjust the benchmark GMD event analysis to account for the localized
geoelectric field enhancement of the supplemental GMD event.
Available at http://geomag.usgs.gov/conductivity/.
See the Supplemental Geomagnetic Disturbance Description white paper located on the Project 2013-03 Geomagnetic
Disturbance Mitigation project webpage: http://www.nerc.com/pa/Stand/Pages/Project-2013-03-Geomagnetic-DisturbanceMitigation.aspx.
4
5
Draft 2 of TPL-007-2
October 2017
Page 32 of 48
TPL-007-1 2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
Figure 1: Physiographic Regions of the Continental United States 6
Figure 2: Physiographic Regions of Canada
6
Additional map detail is available at the U.S. Geological Survey: http://geomag.usgs.gov/.
Draft 2 of TPL-007-2
October 2017
Page 33 of 48
TPL-007-1 2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
Table 3: – Geoelectric Field Scaling Factors
Draft 2 of TPL-007-2
October 2017
USGS
Earth model
Scaling Factor
Benchmark Event
(β b)
Scaling Factor
Supplemental
Event
(β s)
AK1A
0.56
0.51
AK1B
0.56
0.51
AP1
0.33
0.30
AP2
0.82
0.78
BR1
0.22
0.22
CL1
0.76
0.73
CO1
0.27
0.25
CP1
0.81
0.77
CP2
0.95
0.86
FL1
0.7476
0.73
CS1
0.41
0.37
IP1
0.94
0.90
IP2
0.28
0.25
IP3
0.93
0.90
IP4
0.41
0.35
NE1
0.81
0.77
PB1
0.62
0.55
PB2
0.46
0.39
PT1
1.17
1.19
SL1
0.53
0.49
SU1
0.93
0.90
BOU
0.28
0.24
FBK
0.56
0.56
PRU
0.21
0.22
BC
0.67
0.62
PRAIRIES
0.96
0.88
SHIELD
1.0
1.0
ATLANTIC
0.79
0.76
Page 34 of 48
TPL-007-1 2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
Rationale: Scaling factors in Table 3 are dependent upon the frequency content of the
reference storm. Consequently, the benchmark GMD event and the supplemental GMD event
may produce different scaling factors for a given earth model.
The scaling factor associated with the benchmark GMD event for the Florida earth model (FL1)
has been updated based on the earth model published on the USGS public website.
Table 4: – Reference Earth Model (Quebec)
Layer Thickness (km)
Resistivity (Ω-m)
15
20,000
10
200
125
1,000
200
100
∞
3
Reference Geomagnetic Field Time Series or Waveform for the Benchmark GMD Event
Waveform for the Benchmark GMD Event 7
The geomagnetic field measurement record of the March 13-14 1989 GMD event, measured at
the NRCanNARCan’s Ottawa geomagnetic observatory, is the basis for the reference
geomagnetic field waveform to be used to calculate the GIC time series, GIC(t), required for
transformer thermal impact assessment.
The geomagnetic latitude of the Ottawa geomagnetic observatory is 55°; therefore, the
amplitudes of the geomagnetic field measurement data were scaled up to the 60° reference
geomagnetic latitude (see Figure 3) such that the resulting peak geoelectric field amplitude
computed using the reference earth model was 8 V/km (see Figures 4 and 5). The Ssampling rate
for the geomagnetic field waveform waveshape is 10 seconds.8 To use this geoelectric field time
series when a different earth model is applicable, it should be scaled with the appropriate
benchmark conductivity scaling factor βb.
Refer to the Benchmark Geomagnetic Disturbance GMD Event Description white paper for details on the determination of the
reference geomagnetic field waveformwaveshape: http://www.nerc.com/pa/stand/Pages/TPL0071RI.aspx.
8 The data file of the benchmark geomagnetic field waveshape waveform is available on the Related Information webpage for
TPL-007-1NERC GMD Task Force project page: http://www.nerc.com/pa/stand/Pages/TPL0071RI.aspx.
7
Draft 2 of TPL-007-2
October 2017
Page 35 of 48
TPL-007-1 2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
Figure 3: Benchmark Geomagnetic Field WaveformWaveshape
Red Bn (Northward), Blue Be (Eastward)
Figure 4: Benchmark Geoelectric Field WaveformWaveshape
EE (Eastward)
Draft 2 of TPL-007-2
October 2017
Page 36 of 48
TPL-007-1 2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
Figure 5: Benchmark Geoelectric Field WaveformWaveshape
EN (Northward)
1.5.1.4.
Reference Geomagnetic Field Time Series or Waveform for the Supplemental GMD
Event9
The geomagnetic field measurement record of the March 13-14, 1989 GMD event, measured at
the NRCan Ottawa geomagnetic observatory, is the basis for the reference geomagnetic field
waveform to be used to calculate the GIC time series, GIC(t), required for transformer thermal
impact assessment for the supplemental GMD event. The supplemental GMD event waveform
differs from the benchmark GMD event waveform in that the supplemental GMD event
waveform has a local enhancement.
The geomagnetic latitude of the Ottawa geomagnetic observatory is 55°; therefore, the
amplitudes of the geomagnetic field measurement data were scaled up to the 60° reference
geomagnetic latitude (see Figure 6) such that the resulting peak geoelectric field amplitude
computed using the reference earth model was 12 V/km (see Figure7). The sampling rate for the
geomagnetic field waveform is 10 seconds. 10 To use this geoelectric field time series when a
different earth model is applicable, it should be scaled with the appropriate supplemental
conductivity scaling factor βs.
Refer to the Supplemental Geomagnetic Disturbance Event Description white paper for details on the determination of the
reference geomagnetic field waveform: http://www.nerc.com/pa/Stand/Pages/Project-2013-03-Geomagnetic-DisturbanceMitigation.aspx.
10 The data file of the benchmark geomagnetic field waveform is available on the NERC GMD Task Force project webpage:
http://www.nerc.com/comm/PC/Pages/Geomagnetic-Disturbance-Task-Force-(GMDTF)-2013.aspx.
9
Draft 2 of TPL-007-2
October 2017
Page 37 of 48
TPL-007-1 2 – Transmission System Planned Performance for Geomagnetic Disturbance Events
4000
2000
Time (min)
200
400
600
800
1000
1200
1400
1600
1800
2000
Bx, By (nT)
0
-2000
-4000
-6000
-8000
-10000
Figure 6: Supplemental Geomagnetic Field Waveform
Red BN (Northward), Blue BE (Eastward)
12 V/km
Figure 7: Supplemental Geoelectric Field Waveform
Blue EN (Northward), Red EE (Eastward)
Draft 2 of TPL-007-2
October 2017
Page 38 of 48
TPL-007-2 – Supplemental Material
Guidelines and Technical Basis
The diagram below provides an overall view of the GMD Vulnerability Assessment process:
Geomagnetic
Field
B(t)
Earth
Conductivity
Model
Potential
Mitigation
Measures
Geoelectric
Field
E(t)
dc
System
Model
GIC
Transformer vars
Model
(Electrical)
GIC(t)
Power Flow
Analysis
Transformer
Model
(Thermal)
Fail
Bus
Voltages
Line Loading &
var Reserves
Assessment
Criteria
Operating
Procedures
and
Pass
Mitigation
Measures
(if needed)
Temp(t)
Critical Temperatures
The requirements in this standard cover various aspects of the GMD Vulnerability Assessment
process.
Benchmark GMD Event (Attachment 1)
The benchmark GMD event defines the geoelectric field values used to compute GIC flows that
are needed to conduct a benchmark GMD Vulnerability Assessment. The Benchmark
Geomagnetic Disturbance Event Description, May 2016 11A white paper that includes the event
description, analysis, and example calculations is available on the Project 2013-03 Geomagnetic
Disturbance Mitigation project page.
Supplemental GMD Event (Attachment 1)
The supplemental GMD event defines the geoelectric field values used to compute GIC flows that
are needed to conduct a supplemental GMD Vulnerability Assessment. The Supplemental
Geomagnetic Disturbance Event Description, October 2017 12 white paper includes the event
description and analysis.
Requirement R2
A GMD Vulnerability Assessment requires a GIC System model, which is a dc representation of
the System, to calculate GIC flow. In a GMD Vulnerability Assessment, GIC simulations are used
to determine transformer Reactive Power absorption and transformer thermal response. Details
for developing the GIC System model are provided in the NERC GMD Task Force guide:
11
12
http://www.nerc.com/pa/stand/Pages/TPL0071RI.aspx.
http://www.nerc.com/pa/Stand/Pages/Project-2013-03-Geomagnetic-Disturbance-Mitigation.aspx.
Draft 2 of TPL-007-2
October 2017
Page 39 of 48
TPL-007-2 – Supplemental Material
Application Guide for Computing Geomagnetically-Induced Current in the Bulk Power System,
December 2013.13
Underground pipe-type cables present a special modeling situation in that the steel pipe that
encloses the power conductors significantly reduces the geoelectric field induced into the
conductors themselves, while they remain a path for GIC. Solid dielectric cables that are not
enclosed by a steel pipe will not experience a reduction in the induced geoelectric field. A
planning entity should account for special modeling situations in the GIC system model, if
applicable.
Requirement R4
The Geomagnetic Disturbance GMD Planning Guide, 14 December 2013 developed by the NERC
GMD Task Force provides technical information on GMD-specific considerations for planning
studies.It is available at:
Requirement R5
The benchmark transformer thermal impact assessment of transformers specified in
Requirement R6 is based on GIC information for the Benchmark benchmark GMD Event. This GIC
information is determined by the planning entity through simulation of the GIC System model
and must be provided to the entity responsible for conducting the thermal impact assessment.
GIC information should be provided in accordance with Requirement R5 each time the GMD
Vulnerability Assessment is performed since, by definition, the GMD Vulnerability Assessment
includes a documented evaluation of susceptibility to localized equipment damage due to GMD.
The maximum effective GIC value provided in Part 5.1 is used for the benchmark transformer
thermal impact assessment. Only those transformers that experience an effective GIC value of
75 A or greater per phase require evaluation in Requirement R6.
http://www.nerc.com/comm/PC/Geomagnetic%20Disturbance%20Task%20Force%20GMDTF%202013/GIC%20Application
%20Guide%202013_approved.pdf.
14 http://www.nerc.com/comm/PC/Geomagnetic%20Disturbance%20Task%20Force%20GMDTF%202013/GMD%20Planning
%20Guide_approved.pdf.
13
Draft 2 of TPL-007-2
October 2017
Page 40 of 48
TPL-007-2 – Supplemental Material
GIC(t) provided in Part 5.2 is used to convert the steady state GIC flows to time-series GIC data
for the benchmark transformer thermal impact assessment of transformers. This information
may be needed by one or more of the methods for performing a benchmark thermal impact
assessment. Additional information is in the following section and the Transformer Thermal
Impact Assessment White Paper, 15 October 2017thermal assessment whitepaper.
The peak GIC value of 75 Amps per phase has been shown through thermal modeling to be a
conservative threshold below which the risk of exceeding known temperature limits established
by technical organizations is low.
Requirement R6
The benchmark thermal impact assessment of a power transformer may be based on
manufacturer-provided GIC capability curves, thermal response simulation, thermal impact
screening, or other technically justified means. Approaches for conducting the assessment are
presented in the Transformer Thermal Impact Assessment wWhite pPaper posted on the project
pageERO Enterprise-Endorsed Implementation Guidance 16 for this requirement. This EROEndorsed document is posted on the NERC Compliance Guidance 17 webpage.
Transformers are exempt from the benchmark thermal impact assessment requirement if the
effective GIC value for the transformer is less than 75 A per phase, as determined by a GIC analysis
of the System. Justification for this criterion is provided in the Screening Criterion for Transformer
Thermal Impact Assessment wWhite pPaper posted on the project page, 18 October 2017. A
documented design specification exceeding this value is also a justifiable threshold criterion that
exempts a transformer from Requirement R6.
The benchmark threshold criteria and its associated transformer thermal impact must be
evaluated on the basis of effective GIC. Refer to the white papers for additional information.
Requirement R7
Technical considerations for GMD mitigation planning, including operating and equipment
strategies, are available in Chapter 5 of the Geomagnetic Disturbance GMD Planning Guide, 19
December 2013. Additional information is available in the 2012 Special Reliability Assessment
Interim Report: Effects of Geomagnetic Disturbances on the Bulk-Power System, 20 February 2012.
http://www.nerc.com/pa/Stand/Pages/Project-2013-03-Geomagnetic-Disturbance-Mitigation.aspx.
http://www.nerc.com/pa/comp/guidance/EROEndorsedImplementationGuidance/TPL-007-1_Transformer_Thermal_Impact_
Assessment_White_Paper.pdf.
17 http://www.nerc.com/pa/comp/guidance/Pages/default.aspx.
18 http://www.nerc.com/pa/Stand/Pages/Project-2013-03-Geomagnetic-Disturbance-Mitigation.aspx.
19 http://www.nerc.com/comm/PC/Geomagnetic%20Disturbance%20Task%20Force%20GMDTF%202013/GMD%20Planning
%20Guide_approved.pdf.
20 http://www.nerc.com/pa/RAPA/ra/Reliability%20Assessments%20DL/2012GMD.pdf.
15
16
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Requirement R8
The Geomagnetic Disturbance Planning Guide, 21 December 2013 developed by the NERC GMD
Task Force provides technical information on GMD-specific considerations for planning studies.
The supplemental GMD Vulnerability Assessment process is similar to the benchmark GMD
Vulnerability Assessment process described under Requirement R4.
Requirement R9
The supplemental thermal impact assessment specified of transformers in Requirement R10 is
based on GIC information for the supplemental GMD Event. This GIC information is determined
by the planning entity through simulation of the GIC System model and must be provided to the
entity responsible for conducting the thermal impact assessment. GIC information should be
provided in accordance with Requirement R9 each time the GMD Vulnerability Assessment is
performed since, by definition, the GMD Vulnerability Assessment includes a documented
evaluation of susceptibility to localized equipment damage due to GMD.
The maximum effective GIC value provided in Part 9.1 is used for the supplemental thermal
impact assessment. Only those transformers that experience an effective GIC value of 85 A or
greater per phase require evaluation in Requirement R10.
GIC(t) provided in Part 9.2 is used to convert the steady state GIC flows to time-series GIC data
for the supplemental thermal impact assessment of transformers. This information may be
needed by one or more of the methods for performing a supplemental thermal impact
assessment. Additional information is in the following section.
The peak GIC value of 85 Amps per phase has been shown through thermal modeling to be a
conservative threshold below which the risk of exceeding known temperature limits established
by technical organizations is low.
Requirement R10
The supplemental thermal impact assessment of a power transformer may be based on
manufacturer-provided GIC capability curves, thermal response simulation, thermal impact
screening, or other technically justified means. Approaches for conducting the assessment are
presented in the Transformer Thermal Impact Assessment White Paper ERO Enterprise-Endorsed
Implementation Guidance 22 discussed in the Requirement R6 section above. A later version of the
Transformer Thermal Impact Assessment White Paper, 23 October 2017, has been developed to
http://www.nerc.com/comm/PC/Geomagnetic%20Disturbance%20Task%20Force%20GMDTF%202013/GMD%20Planning
%20Guide_approved.pdf.
22 http://www.nerc.com/pa/comp/guidance/EROEndorsedImplementationGuidance/TPL-007-1_Transformer_Thermal_Impact_
Assessment_White_Paper.pdf.
23 http://www.nerc.com/pa/Stand/Pages/Project-2013-03-Geomagnetic-Disturbance-Mitigation.aspx.
21
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TPL-007-2 – Supplemental Material
include updated information pertinent to the supplemental GMD event and supplemental
thermal impact assessment.
Transformers are exempt from the supplemental thermal impact assessment requirement if the
effective GIC value for the transformer is less than 85 A per phase, as determined by a GIC analysis
of the System. Justification for this criterion is provided in the revised Screening Criterion for
Transformer Thermal Impact Assessment White Paper, 24 October 2017. A documented design
specification exceeding this value is also a justifiable threshold criterion that exempts a
transformer from Requirement R10.
The supplemental threshold criteria and its associated transformer thermal impact must be
evaluated on the basis of effective GIC. Refer to the white papers for additional information.
Requirement R11
Technical considerations for GIC monitoring are contained in Chapter 6 of the 2012 Special
Reliability Assessment Interim Report: Effects of Geomagnetic Disturbances on the Bulk-Power
System, 25 February 2012. GIC monitoring is generally performed by Hall effect transducers that
are attached to the neutral of the wye-grounded transformer. Data from GIC monitors is useful
for model validation and situational awareness.
Responsible entities consider the following in developing a process for obtaining GIC monitor
data:
24
25
•
Monitor locations. An entity's operating process may be constrained by location of
existing GIC monitors. However, when planning for additional GIC monitoring installations
consider that data from monitors located in areas found to have high GIC based on system
studies may provide more useful information for validation and situational awareness
purposes. Conversely, data from GIC monitors that are located in the vicinity of
transportation systems using direct current (e.g., subways or light rail) may be unreliable.
•
Monitor specifications. Capabilities of Hall effect transducers, existing and planned,
should be considered in the operating process. When planning new GIC monitor
installations, consider monitor data range (e.g., -500 A through + 500 A) and ambient
temperature ratings consistent with temperatures in the region in which the monitor will
be installed.
•
Sampling Interval. An entity's operating process may be constrained by capabilities of
existing GIC monitors. However, when possible specify data sampling during periods of
interest at a rate of 10 seconds or faster.
•
Collection Periods. The process should specify when the entity expects GIC data to be
collected. For example, collection could be required during periods where the Kp index is
http://www.nerc.com/pa/Stand/Pages/Project-2013-03-Geomagnetic-Disturbance-Mitigation.aspx.
http://www.nerc.com/pa/RAPA/ra/Reliability%20Assessments%20DL/2012GMD.pdf.
Draft 2 of TPL-007-2
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TPL-007-2 – Supplemental Material
above a threshold, or when GIC values are above a threshold. Determining when to
discontinue collecting GIC data should also be specified to maintain consistency in data
collection.
•
Data format. Specify time and value formats. For example, Greenwich Mean Time (GMT)
(MM/DD/YYYY HH:MM:SS) and GIC Value (Ampere). Positive (+) and negative (-) signs
indicate direction of GIC flow. Positive reference is flow from ground into transformer
neutral. Time fields should indicate the sampled time rather than system or SCADA time
if supported by the GIC monitor system.
•
Data retention. The entity's process should specify data retention periods, for example 1
year. Data retention periods should be adequately long to support availability for the
entity's model validation process and external reporting requirements, if any.
•
Additional information. The entity's process should specify collection of other
information necessary for making the data useful, for example monitor location and type
of neutral connection (e.g., three-phase or single-phase).
Requirement R12
Magnetometers measure changes in the earth's magnetic field. Entities should obtain data from
the nearest accessible magnetometer. Sources of magnetometer data include:
26
•
Observatories such as those operated by U.S. Geological Survey and Natural Resources
Canada, see figure below for locations: 26
•
•
Research institutions and academic universities;
Entities with installed magnetometers.
http://www.intermagnet.org/index-eng.php.
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TPL-007-2 – Supplemental Material
Entities that choose to install magnetometers should consider equipment specifications and data
format protocols contained in the latest version of the INTERMAGNET Technical Reference
Manual, Version 4.6, 2012. 27
Rationale
During development of TPL-007-1this standard, text boxes were embedded within the standard
to explain the rationale for various parts of the standard. Upon BOT approval, tThe text from the
rationale text boxes was moved to this section upon approval of TPL-007-1 by the NERC Board of
Trustees. In developing TPL-007-2, the SDT has made changes to the sections below only when
necessary for clarity. Changes are marked with brackets [ ].
Rationale for Applicability:
Instrumentation transformers and station service transformers do not have significant impact on
geomagnetically-induced current (GIC) flows; therefore, these transformers are not included in
the applicability for this standard.
Terminal voltage describes line-to-line voltage.
Rationale for R1:
In some areas, planning entities may determine that the most effective approach to conduct a
GMD Vulnerability Assessment is through a regional planning organization. No requirement in
the standard is intended to prohibit a collaborative approach where roles and responsibilities are
determined by a planning organization made up of one or more Planning Coordinator(s).
Rationale for R2:
A GMD Vulnerability Assessment requires a GIC System model to calculate GIC flow which is used
to determine transformer Reactive Power absorption and transformer thermal response.
Guidance for developing the GIC System model is provided in the GIC Application Guide
Computing Geomagnetically-Induced Current in the Bulk-Power System, 28 December 2013,
developed by the NERC GMD Task Force. and available at:
The System model specified in Requirement R2 is used in conducting steady state power flow
analysis that accounts for the Reactive Power absorption of power transformer(s) due to GIC in
the System.
The GIC System model includes all power transformer(s) with a high side, wye-grounded winding
with terminal voltage greater than 200 kV. The model is used to calculate GIC flow in the network.
http://www.intermagnet.org/publications/intermag_4-6.pdf.
http://www.nerc.com/comm/PC/Geomagnetic%20Disturbance%20Task%20Force%20GMDTF%202013/GIC%20Application
%20Guide%202013_approved.pdf.
27
28
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The projected System condition for GMD planning may include adjustments to the System that
are executable in response to space weather information. These adjustments could include, for
example, recalling or postponing maintenance outages.
The Violation Risk Factor (VRF) for Requirement R2 is changed from Medium to High. This change
is for consistency with the VRF for approved standard TPL-001-4 Requirement R1, which is
proposed for revision in the NERC filing dated August 29, 2014 (Docket No. RM12-1-000). NERC
guidelines require consistency among Reliability Standards.
Rationale for R3:
Requirement R3 allows a responsible entity the flexibility to determine the System steady state
voltage criteria for System steady state performance in Table 1. Steady state voltage limits are
an example of System steady state performance criteria.
Rationale for R4:
The GMD Vulnerability Assessment includes steady state power flow analysis and the supporting
study or studies using the models specified in Requirement R2 that account for the effects of GIC.
Performance criteria are specified in Table 1.
At least one System On-Peak Load and at least one System Off-Peak Load must be examined in
the analysis.
Distribution of GMD Vulnerability Assessment results provides a means for sharing relevant
information with other entities responsible for planning reliability. Results of GIC studies may
affect neighboring systems and should be taken into account by planners.
The Geomagnetic Disturbance GMD Planning Guide, 29 December 2013 developed by the NERC
GMD Task Force provides technical information on GMD-specific considerations for planning
studies. It is available at:The provision of information in Requirement R4, Part 4.3, shall be subject
to the legal and regulatory obligations for the disclosure of confidential and/or sensitive
information.
Rationale for R5:
This GIC information is necessary for determining the thermal impact of GIC on transformers in
the planning area and must be provided to entities responsible for performing the thermal impact
assessment so that they can accurately perform the assessment. GIC information should be
provided in accordance with Requirement R5 as part of the GMD Vulnerability Assessment
process since, by definition, the GMD Vulnerability Assessment includes documented evaluation
of susceptibility to localized equipment damage due to GMD.
The maximum effective GIC value provided in Part 5.1 is used for transformer thermal impact
assessment.
http://www.nerc.com/comm/PC/Geomagnetic%20Disturbance%20Task%20Force%20GMDTF%202013/GMD%20Planning
%20Guide_approved.pdf.
29
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GIC(t) provided in Part 5.2 can alternatively be used to convert the steady state GIC flows to timeseries GIC data for transformer thermal impact assessment. This information may be needed by
one or more of the methods for performing a thermal impact assessment. Additional guidance is
available in the Transformer Thermal Impact Assessment wWhite pPaper, 30 October 2017.
A Transmission Owner or Generator Owner that desires GIC(t) may request it from the planning
entity. The planning entity shall provide GIC(t) upon request once GIC has been calculated, but
no later than 90 calendar days after receipt of a request from the owner and after completion of
Requirement R5, Part 5.1.
The provision of information in Requirement R5 shall be subject to the legal and regulatory
obligations for the disclosure of confidential and/or sensitive information.
Rationale for R6:
The transformer thermal impact screening criterion has been revised from 15 A per phase to 75
A per phase [for the benchmark GMD event]. Only those transformers that experience an
effective GIC value of 75 A per phase or greater require evaluation in Requirement R6. The
justification is provided in the Screening Criterion for Transformer Thermal Impact Assessment
White Paper, 31 October 2017white paper.
The thermal impact assessment may be based on manufacturer-provided GIC capability curves,
thermal response simulation, thermal impact screening, or other technically justified means. The
transformer thermal assessment will be repeated or reviewed using previous assessment results
each time the planning entity performs a GMD Vulnerability Assessment and provides GIC
information as specified in Requirement R5. Approaches for conducting the assessment are
presented in the Transformer Thermal Impact Assessment White Paper, 32 October 2017.
Thermal impact assessments are provided to the planning entity, as determined in Requirement
R1, so that identified issues can be included in the GMD Vulnerability Assessment (R4), and the
Corrective Action Plan (R7) as necessary.
Thermal impact assessments of non-BES transformers are not required because those
transformers do not have a wide-area effect on the reliability of the interconnected Transmission
system.
The provision of information in Requirement R6, Part 6.4, shall be subject to the legal and
regulatory obligations for the disclosure of confidential and/or sensitive information.
http://www.nerc.com/pa/Stand/Pages/Project-2013-03-Geomagnetic-Disturbance-Mitigation.aspx.
http://www.nerc.com/pa/Stand/Pages/Project-2013-03-Geomagnetic-Disturbance-Mitigation.aspx.
32 http://www.nerc.com/pa/Stand/Pages/Project-2013-03-Geomagnetic-Disturbance-Mitigation.aspx.
30
31
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Rationale for R7:
Corrective Action Plans are defined in the NERC Glossary of Terms:
A list of actions and an associated timetable for implementation to remedy a specific
problem.
Corrective Action Plans must, subject to the vulnerabilities identified in the assessments, contain
strategies for protecting against the potential impact of the Bbenchmark GMD event, based on
factors such as the age, condition, technical specifications, system configuration, or location of
specific equipment. Chapter 5 of the NERC GMD Task Force Geomagnetic Disturbance GMD
Planning Guide, 33 December 2013 provides a list of mitigating measures that may be appropriate
to address an identified performance issue.
The provision of information in Requirement R7, Part 7.3 [Part 7.5 in TPL-007-2], shall be subject
to the legal and regulatory obligations for the disclosure of confidential and/or sensitive
information.
Rationale for Table 3:
Table 3 has been revised to use the same ground model designation, FL1, as is being used by
USGS. The calculated scaling factor for FL1 is 0.74. [The scaling factor associated with the
benchmark GMD event for the Florida earth model (FL1) has been updated to 0.76 in TPL-007-2
based on the earth model published on the USGS public website.]
http://www.nerc.com/comm/PC/Geomagnetic%20Disturbance%20Task%20Force%20GMDTF%202013/GMD%20Planning
%20Guide_approved.pdf.
33
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| File Type | application/pdf |
| File Title | Microsoft Word - Exhibit A FAC-003-2 Clean and Redline Version.docx |
| Author | baughanc |
| File Modified | 2018-05-10 |
| File Created | 2018-01-09 |