Reliability Standards-FAC-010-2.1

Standard FAC-010-2.1 — System Operating Limits Methodology for the Planning Horizon
A. Introduction
1.

Title:

System Operating Limits Methodology for the Planning Horizon

2.

Number:

FAC-010-2.1

3.

Purpose:
To ensure that System Operating Limits (SOLs) used in the reliable planning of
the Bulk Electric System (BES) are determined based on an established methodology or
methodologies.

4.

Applicability
4.1. Planning Authority

5.

Effective Date:

April 19, 2010

B. Requirements
R1.

R2.

The Planning Authority shall have a documented SOL Methodology for use in developing
SOLs within its Planning Authority Area. This SOL Methodology shall:
R1.1.

Be applicable for developing SOLs used in the planning horizon.

R1.2.

State that SOLs shall not exceed associated Facility Ratings.

R1.3.

Include a description of how to identify the subset of SOLs that qualify as IROLs.

The Planning Authority’s SOL Methodology shall include a requirement that SOLs provide
BES performance consistent with the following:
R2.1.

In the pre-contingency state and with all Facilities in service, the BES shall
demonstrate transient, dynamic and voltage stability; all Facilities shall be within their
Facility Ratings and within their thermal, voltage and stability limits. In the
determination of SOLs, the BES condition used shall reflect expected system
conditions and shall reflect changes to system topology such as Facility outages.

R2.2.

Following the single Contingencies 1 identified in Requirement 2.2.1 through
Requirement 2.2.3, the system shall demonstrate transient, dynamic and voltage
stability; all Facilities shall be operating within their Facility Ratings and within their
thermal, voltage and stability limits; and Cascading or uncontrolled separation shall
not occur.
R2.2.1. Single line to ground or three-phase Fault (whichever is more severe), with
Normal Clearing, on any Faulted generator, line, transformer, or shunt
device.
R2.2.2. Loss of any generator, line, transformer, or shunt device without a Fault.
R2.2.3. Single pole block, with Normal Clearing, in a monopolar or bipolar high
voltage direct current system.

R2.3.

Starting with all Facilities in service, the system’s response to a single Contingency,
may include any of the following:
R2.3.1. Planned or controlled interruption of electric supply to radial customers or
some local network customers connected to or supplied by the Faulted
Facility or by the affected area.

1

The Contingencies identified in R2.2.1 through R2.2.3 are the minimum contingencies that must be studied but are
not necessarily the only Contingencies that should be studied.
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Standard FAC-010-2.1 — System Operating Limits Methodology for the Planning Horizon
R2.3.2. System reconfiguration through manual or automatic control or protection
actions.
R2.4.

To prepare for the next Contingency, system adjustments may be made, including
changes to generation, uses of the transmission system, and the transmission system
topology.

R2.5.

Starting with all Facilities in service and following any of the multiple Contingencies
identified in Reliability Standard TPL-003 the system shall demonstrate transient,
dynamic and voltage stability; all Facilities shall be operating within their Facility
Ratings and within their thermal, voltage and stability limits; and Cascading or
uncontrolled separation shall not occur.

R2.6.

In determining the system’s response to any of the multiple Contingencies, identified
in Reliability Standard TPL-003, in addition to the actions identified in R2.3.1 and
R2.3.2, the following shall be acceptable:
R2.6.1. Planned or controlled interruption of electric supply to customers (load
shedding), the planned removal from service of certain generators, and/or
the curtailment of contracted Firm (non-recallable reserved) electric power
Transfers.

R3.

R4.

R5.

The Planning Authority’s methodology for determining SOLs, shall include, as a minimum, a
description of the following, along with any reliability margins applied for each:
R3.1.

Study model (must include at least the entire Planning Authority Area as well as the
critical modeling details from other Planning Authority Areas that would impact the
Facility or Facilities under study).

R3.2.

Selection of applicable Contingencies.

R3.3.

Level of detail of system models used to determine SOLs.

R3.4.

Allowed uses of Special Protection Systems or Remedial Action Plans.

R3.5.

Anticipated transmission system configuration, generation dispatch and Load level.

R3.6.

Criteria for determining when violating a SOL qualifies as an Interconnection
Reliability Operating Limit (IROL) and criteria for developing any associated IROL
Tv.

The Planning Authority shall issue its SOL Methodology, and any change to that methodology,
to all of the following prior to the effectiveness of the change:
R4.1.

Each adjacent Planning Authority and each Planning Authority that indicated it has a
reliability-related need for the methodology.

R4.2.

Each Reliability Coordinator and Transmission Operator that operates any portion of
the Planning Authority’s Planning Authority Area.

R4.3.

Each Transmission Planner that works in the Planning Authority’s Planning Authority
Area.

If a recipient of the SOL Methodology provides documented technical comments on the
methodology, the Planning Authority shall provide a documented response to that recipient
within 45 calendar days of receipt of those comments. The response shall indicate whether a
change will be made to the SOL Methodology and, if no change will be made to that SOL
Methodology, the reason why. (Retirement approved by FERC effective January 21, 2014.)

C. Measures
M1. The Planning Authority’s SOL Methodology shall address all of the items listed in
Requirement 1 through Requirement 3.
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Standard FAC-010-2.1 — System Operating Limits Methodology for the Planning Horizon
M2. The Planning Authority shall have evidence it issued its SOL Methodology and any changes to
that methodology, including the date they were issued, in accordance with Requirement 4.
If the recipient of the SOL Methodology provides documented comments on its technical
review of that SOL methodology, the Planning Authority that distributed that SOL
Methodology shall have evidence that it provided a written response to that commenter within
45 calendar days of receipt of those comments in accordance with Requirement 5. (Retirement
approved by FERC effective January 21, 2014.)
D. Compliance
1.

Compliance Monitoring Process
1.1. Compliance Monitoring Responsibility
Regional Reliability Organization
1.2. Compliance Monitoring Period and Reset Time Frame
Each Planning Authority shall self-certify its compliance to the Compliance Monitor at
least once every three years. New Planning Authorities shall demonstrate compliance
through an on-site audit conducted by the Compliance Monitor within the first year that it
commences operation. The Compliance Monitor shall also conduct an on-site audit once
every nine years and an investigation upon complaint to assess performance.
The Performance-Reset Period shall be twelve months from the last non-compliance.
1.3. Data Retention
The Planning Authority shall keep all superseded portions to its SOL Methodology for 12
months beyond the date of the change in that methodology and shall keep all documented
comments on its SOL Methodology and associated responses for three years. In addition,
entities found non-compliant shall keep information related to the non-compliance until
found compliant. (Deleted text retired-Retirement approved by FERC effective January
21, 2014.)
The Compliance Monitor shall keep the last audit and all subsequent compliance records.
1.4. Additional Compliance Information
The Planning Authority shall make the following available for inspection during an onsite audit by the Compliance Monitor or within 15 business days of a request as part of an
investigation upon complaint:
1.4.1

SOL Methodology.
Documented comments provided by a recipient of the SOL Methodology on its
technical review of a SOL Methodology, and the associated responses.
(Retirement approved by FERC effective January 21, 2014.)

2.

1.4.2

Superseded portions of its SOL Methodology that had been made within the past
12 months.

1.4.3

Evidence that the SOL Methodology and any changes to the methodology that
occurred within the past 12 months were issued to all required entities.

Levels of Non-Compliance for Western Interconnection: (To be replaced with VSLs once
developed and approved by WECC)
2.1. Level 1:
There shall be a level one non-compliance if either of the following
conditions exists:
2.1.1

The SOL Methodology did not include a statement indicating that Facility
Ratings shall not be exceeded.
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Standard FAC-010-2.1 — System Operating Limits Methodology for the Planning Horizon
2.1.2

No evidence of responses to a recipient’s comments on the SOL Methodology.
(Retirement approved by FERC effective January 21, 2014.)

2.2. Level 2:
The SOL Methodology did not include a requirement to address all of the
elements in R2.1 through R2.3 and E1.
2.3. Level 3:
There shall be a level three non-compliance if any of the following
conditions exists:
2.3.1

The SOL Methodology did not include a statement indicating that Facility
Ratings shall not be exceeded and the methodology did not include evaluation of
system response to one of the three types of single Contingencies identified in
R2.2.

2.3.2

The SOL Methodology did not include a statement indicating that Facility
Ratings shall not be exceeded and the methodology did not include evaluation of
system response to two of the seven types of multiple Contingencies identified in
E1.1.

2.3.3

The System Operating Limits Methodology did not include a statement
indicating that Facility Ratings shall not be exceeded and the methodology did
not address two of the six required topics in R3.

2.4. Level 4:
with R4

The SOL Methodology was not issued to all required entities in accordance

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Standard FAC-010-2.1 — System Operating Limits Methodology for the Planning Horizon
3.

Violation Severity Levels:

Requirement

Lower

Moderate

High

Severe

R1

Not applicable.

The Planning Authority has a
documented SOL Methodology
for use in developing SOLs
within its Planning Authority
Area, but it does not address
R1.2

The Planning Authority has a
documented SOL Methodology
for use in developing SOLs
within its Planning Authority
Area, but it does not address
R1.3.

The Planning Authority has a
documented SOL Methodology
for use in developing SOLs
within its Planning Authority
Area, but it does not address
R1.1.
OR
The Planning Authority has no
documented SOL Methodology
for use in developing SOLs
within its Planning Authority
Area.

R2

The Planning Authority’s SOL
Methodology is missing one
requirement as described in
R2.1, R2.2, R2.3, R2.4, R2.5, or
R2.6.

The Planning Authority’s SOL
Methodology is missing two
requirements as described in
R2.1, R2.2, R2.3, R2.4, R2.5, or
R2.6

The Planning Authority’s SOL
Methodology is missing three
requirements as described in
R2.1, R2.2, R2.3, R2.4, R2.5, or
R2.6.

The Planning Authority’s SOL
Methodology is missing four or
more requirements as described
in R2.1, R2.2-, R2.3, R2.4, R2.5,
or R2.6

R3

The Planning Authority has a
methodology for determining
SOLs that includes a description
for all but one of the following:
R3.1 through R3.6.

The Planning Authority has a
methodology for determining
SOLs that includes a description
for all but two of the following:
R3.1 through R3.6.

The Planning Authority has a
methodology for determining
SOLs that includes a description
for all but three of the following:
R3.1 through R3.6.

The Planning Authority has a
methodology for determining
SOLs that is missing a
description of four or more of the
following: R3.1 through R3.6.

R4

One or both of the following:
The Planning Authority issued its
SOL Methodology and changes
to that methodology to all but
one of the required entities.
For a change in methodology,
the changed methodology was
provided up to 30 calendar days
after the effectiveness of the
change.

One of the following:
The Planning Authority issued its
SOL Methodology and changes
to that methodology to all but
one of the required entities AND
for a change in methodology, the
changed methodology was
provided 30 calendar days or
more, but less than 60 calendar
days after the effectiveness of
the change.
OR

One of the following:
The Planning Authority issued its
SOL Methodology and changes
to that methodology to all but
one of the required entities AND
for a change in methodology, the
changed methodology was
provided 60 calendar days or
more, but less than 90 calendar
days after the effectiveness of
the change.
OR

One of the following:
The Planning Authority failed to
issue its SOL Methodology and
changes to that methodology to
more than three of the required
entities.
The Planning Authority issued its
SOL Methodology and changes
to that methodology to all but
one of the required entities AND
for a change in methodology, the
changed methodology was

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Standard FAC-010-2.1 — System Operating Limits Methodology for the Planning Horizon

Requirement

R5
(Retirement

Lower

The Planning Authority received
documented technical comments
on its SOL Methodology and

Moderate

High

Severe

The Planning Authority issued its
SOL Methodology and changes
to that methodology to all but
two of the required entities AND
for a change in methodology, the
changed methodology was
provided up to 30 calendar days
after the effectiveness of the
change.

The Planning Authority issued its
SOL Methodology and changes
to that methodology to all but
two of the required entities AND
for a change in methodology, the
changed methodology was
provided 30 calendar days or
more, but less than 60 calendar
days after the effectiveness of
the change.
OR
The Planning Authority issued its
SOL Methodology and changes
to that methodology to all but
three of the required entities
AND for a change in
methodology, the changed
methodology was provided up to
30 calendar days after the
effectiveness of the change.

provided 90 calendar days or
more after the effectiveness of
the change.
OR
The Planning Authority issued its
SOL Methodology and changes
to that methodology to all but
two of the required entities AND
for a change in methodology, the
changed methodology was
provided 60 calendar days or
more, but less than 90 calendar
days after the effectiveness of
the change.
OR
The Planning Authority issued its
SOL Methodology and changes
to that methodology to all but
three of the required entities
AND for a change in
methodology, the changed
methodology was provided 30
calendar days or more, but less
than 60 calendar days after the
effectiveness of the change.
The Planning Authority issued its
SOL Methodology and changes
to that methodology to all but
four of the required entities AND
for a change in methodology, the
changed methodology was
provided up to 30 calendar days
after the effectiveness of the
change.

The Planning Authority received
documented technical comments
on its SOL Methodology and

The Planning Authority received
documented technical comments
on its SOL Methodology and

The Planning Authority received
documented technical comments
on its SOL Methodology and

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Standard FAC-010-2.1 — System Operating Limits Methodology for the Planning Horizon

Requirement

Lower

Moderate

High

Severe

approved by FERC
effective January
21, 2014.)

provided a complete response in
a time period that was longer
than 45 calendar days but less
than 60 calendar days.

provided a complete response in
a time period that was 60
calendar days or longer but less
than 75 calendar days.

provided a complete response in
a time period that was 75
calendar days or longer but less
than 90 calendar days.
OR
The Planning Authority’s
response to documented
technical comments on its SOL
Methodology indicated that a
change will not be made, but did
not include an explanation of
why the change will not be
made.

provided a complete response in
a time period that was 90
calendar days or longer.
OR
The Planning Authority’s
response to documented
technical comments on its SOL
Methodology did not indicate
whether a change will be made
to the SOL Methodology.

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Standard FAC-010-2.1 — System Operating Limits Methodology for the Planning Horizon
E. Regional Differences
1.

The following Interconnection-wide Regional Difference shall be applicable in the Western
Interconnection:
1.1. As governed by the requirements of R2.5 and R2.6, starting with all Facilities in service,
shall require the evaluation of the following multiple Facility Contingencies when
establishing SOLs:
1.1.1

Simultaneous permanent phase to ground Faults on different phases of each of
two adjacent transmission circuits on a multiple circuit tower, with Normal
Clearing. If multiple circuit towers are used only for station entrance and exit
purposes, and if they do not exceed five towers at each station, then this
condition is an acceptable risk and therefore can be excluded.

1.1.2

A permanent phase to ground Fault on any generator, transmission circuit,
transformer, or bus section with Delayed Fault Clearing except for bus
sectionalizing breakers or bus-tie breakers addressed in E1.1.7

1.1.3

Simultaneous permanent loss of both poles of a direct current bipolar Facility
without an alternating current Fault.

1.1.4

The failure of a circuit breaker associated with a Special Protection System to
operate when required following: the loss of any element without a Fault; or a
permanent phase to ground Fault, with Normal Clearing, on any transmission
circuit, transformer or bus section.

1.1.5

A non-three phase Fault with Normal Clearing on common mode Contingency of
two adjacent circuits on separate towers unless the event frequency is determined
to be less than one in thirty years.

1.1.6

A common mode outage of two generating units connected to the same
switchyard, not otherwise addressed by FAC-010.

1.1.7

The loss of multiple bus sections as a result of failure or delayed clearing of a bus
tie or bus sectionalizing breaker to clear a permanent Phase to Ground Fault.

1.2. SOLs shall be established such that for multiple Facility Contingencies in E1.1.1 through
E1.1.5 operation within the SOL shall provide system performance consistent with the
following:
1.2.1

All Facilities are operating within their applicable Post-Contingency thermal,
frequency and voltage limits.

1.2.2

Cascading does not occur.

1.2.3

Uncontrolled separation of the system does not occur.

1.2.4

The system demonstrates transient, dynamic and voltage stability.

1.2.5

Depending on system design and expected system impacts, the controlled
interruption of electric supply to customers (load shedding), the planned removal
from service of certain generators, and/or the curtailment of contracted firm (nonrecallable reserved) electric power transfers may be necessary to maintain the
overall security of the interconnected transmission systems.

1.2.6

Interruption of firm transfer, Load or system reconfiguration is permitted through
manual or automatic control or protection actions.

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Standard FAC-010-2.1 — System Operating Limits Methodology for the Planning Horizon
1.2.7

To prepare for the next Contingency, system adjustments are permitted, including
changes to generation, Load and the transmission system topology when
determining limits.

1.3. SOLs shall be established such that for multiple Facility Contingencies in E1.1.6 through
E1.1.7 operation within the SOL shall provide system performance consistent with the
following with respect to impacts on other systems:
1.3.1

Cascading does not occur.

1.4. The Western Interconnection may make changes (performance category adjustments) to
the Contingencies required to be studied and/or the required responses to Contingencies
for specific facilities based on actual system performance and robust design. Such
changes will apply in determining SOLs.
Version History
Version

Date

Action

Change Tracking

1

November 1,
2006

Adopted by Board of Trustees

New

1

November 1,
2006

Fixed typo. Removed the word “each” from
the 1st sentence of section D.1.3, Data
Retention.

01/11/07

2

June 24, 2008

Adopted by Board of Trustees; FERC Order
705

Revised

Changed the effective date to July 1, 2008
Changed “Cascading Outage” to
“Cascading”
Replaced Levels of Non-compliance with
Violation Severity Levels

Revised

January 22,
2010

Updated effective date and footer to April
29, 2009 based on the March 20, 2009
FERC Order

Update

2.1

November 5,
2009

Adopted by the Board of Trustees — errata
change Section E1.1 modified to reflect the
renumbering of requirements R2.4 and R2.5
from FAC-010-1 to R2.5 and R2.6 in FAC010-2.

Errata

2.1

April 19, 2010

Errata

2.1

February 7,
2013

FERC Approved — errata change Section
E1.1 modified to reflect the renumbering of
requirements R2.4 and R2.5 from FAC-0101 to R2.5 and R2.6 in FAC-010-2.
R5 and associated elements approved by
NERC Board of Trustees for retirement as
part of the Paragraph 81 project (Project
2013-02) pending applicable regulatory
approval.

2

2

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Standard FAC-010-2.1 — System Operating Limits Methodology for the Planning Horizon

2.1

November 21,
2013

R5 and associated elements approved by
FERC for retirement as part of the
Paragraph 81 project (Project 2013-02)

2.1

February 24,
2014

Updated VSLs based on June 24, 2013
approval.

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