TPL-007-1 NERC petition

UNITED STATES OF AMERICA
BEFORE THE
FEDERAL ENERGY REGULATORY COMMISSION

North American Electric Reliability
Corporation

)
)

Docket No. _______

PETITION OF THE
NORTH AMERICAN ELECTRIC RELIABILITY CORPORATION
FOR APPROVAL OF PROPOSED RELIABILITY STANDARD
TPL-007-1 TRANSMISSION SYSTEM PLANNED PERFORMANCE FOR
GEOMAGNETIC DISTURBANCE EVENTS
Gerald W. Cauley
President and Chief Executive Officer
North American Electric Reliability Corporation
3353 Peachtree Road, N.E.
Suite 600, North Tower
Atlanta, GA 30326
(404) 446-2560
(404) 446-2595 – facsimile

Charles A. Berardesco
Senior Vice President and General Counsel
Holly A. Hawkins
Associate General Counsel
Lauren A. Perotti
Counsel
North American Electric Reliability Corporation
1325 G Street, N.W., Suite 600
Washington, D.C. 20005
(202) 400-3000
(202) 644-8099 – facsimile
[email protected]
[email protected]
[email protected]
Counsel for the North American Electric
Reliability Corporation

January 21, 2014

TABLE OF CONTENTS

I.

EXECUTIVE SUMMARY .................................................................................................... 2

II.

NOTICES AND COMMUNICATIONS ................................................................................ 5

III. BACKGROUND .................................................................................................................... 5
A.

Regulatory Framework ..................................................................................................... 6

B.

NERC Reliability Standards Development Process ......................................................... 7

C.

History of Project 2013-03, Geomagnetic Disturbance Mitigation ................................. 8

IV. JUSTIFICATION FOR APPROVAL .................................................................................. 10
A.

Proposed Definition of “Geomagnetic Disturbance Vulnerability Assessment............. 11

or “GMD Vulnerability Assessment" ....................................................................................... 11
B.
Applicability of Proposed Reliability Standard TPL-007-1 – Transmission System
Planned Performance for Geomagnetic Disturbance Events .................................................... 13
C.

The Benchmark GMD Event.......................................................................................... 15
1.

The Proposed Benchmark GMD Event Sets a High Benchmark for Reliability........ 16

2.
The Benchmark GMD Event Can be Directly Applied to the Performance of GMD
Vulnerability Assessments .................................................................................................... 18
3.
The Proposed Benchmark GMD Event Includes the Necessary Parameters to Support
Assessment of Known GMD Related Vulnerabilities .......................................................... 19
4.
Additional Benchmark GMD Event Considerations in the Standards Development
Process .................................................................................................................................. 20
D.

Transformer Thermal Impact Assessment ..................................................................... 23

E.
Requirements in Proposed Reliability Standard TPL-007-1 – Transmission System
Planned Performance for Geomagnetic Disturbance Events .................................................... 24
F.

Implementation of Proposed Reliability Standard TPL-007-1 ...................................... 33

G.

Commission Directives and Issues Addressed ............................................................... 35
1.

Benchmark GMD Event and Timing: Order No. 779, Paragraph 2 ........................... 35

2.

Costs and Benefits: Order No. 779, Paragraph 28...................................................... 36

3.

Identification of Facilities and Wide-Area Assessment: Order No. 779, ................... 37

Paragraph 51 ......................................................................................................................... 37
4.

Assessment Parameters: Order No. 779, Paragraph 67 .............................................. 38

5.

Improvements in Scientific Understanding of GMDs: Order No. 779,...................... 41

Paragraph 68 ......................................................................................................................... 41
ii

TABLE OF CONTENTS
6.

Plans to Protect Against Instability, Uncontrolled Separation, or .............................. 41

Cascading Failures of the Bulk-Power System: Order No. 779, Paragraph 79 .................... 41
7.
Performance of Vulnerability Assessments and Developing Plans to Mitigate
Identified Vulnerabilities: Order No. 779, Paragraph 82 ...................................................... 42

H.
V.

8.

Strict Liability: Order No. 779, Paragraph 84 ............................................................ 43

9.

Automatic Blocking Measures: Order No. 779, Paragraph 85 ................................... 43

10.

Reliability Goals: Order No. 779, Paragraph 86 ........................................................ 44

11.

Implementation Plan: Order No. 779, Paragraph 91 .................................................. 45
Enforceability of Proposed Reliability Standard TPL-007-1 ......................................... 46

CONCLUSION ..................................................................................................................... 48

Exhibit A

Proposed Reliability Standard, TPL-007-1 – Transmission System Planned
Performance for Geomagnetic Disturbance Operations

Exhibit B

Implementation Plan for Proposed Reliability Standard TPL-007-1

Exhibit C

Order No. 672 Criteria for Proposed Reliability Standard TPL-007-1

Exhibit D

Benchmark Geomagnetic Disturbance Event Description

Exhibit E

Transformer Thermal Impact Assessment White Paper

Exhibit F

Screening Criterion for Transformer Thermal Impact Assessment

Exhibit G

Analysis of Violation Risk Factors and Violation Severity Levels

Exhibit H

Consideration of Issues and Directives

Exhibit I

Summary of Development History and Complete Record of Development

Exhibit J

Standard Drafting Team Roster for Project 2013-03, Geomagnetic Disturbance
Mitigation

ii

UNITED STATES OF AMERICA
BEFORE THE
FEDERAL ENERGY REGULATORY COMMISSION

North American Electric Reliability
Corporation

)
)

Docket No. _______

PETITION OF THE
NORTH AMERICAN ELECTRIC RELIABILITY CORPORATION
FOR APPROVAL OF PROPOSED RELIABILITY STANDARD
TPL-007-1 TRANSMISSION SYSTEM PLANNED PERFORMANCE FOR
GEOMAGNETIC DISTURBANCE EVENTS
Pursuant to Section 215(d)(1) of the Federal Power Act (“FPA”)1 and Section 39.52 of the
Federal Energy Regulatory Commission’s (“FERC” or “Commission”) regulations, the North
American Electric Reliability Corporation (“NERC”)3 hereby submits proposed Reliability
Standard TPL-007-1 – Transmission System Planned Performance for Geomagnetic Disturbance
Events and the accompanying definition of “Geomagnetic Disturbance Vulnerability Assessment
or GMD Vulnerability Assessment” (“Definition”) for Commission approval. NERC submits
the proposed Reliability Standard in response to the Commission’s directive in Order No. 779 to
develop a Reliability Standard that requires owners and operators of the Bulk-Power System to
conduct initial and on-going vulnerability assessments of the potential impact of benchmark
geomagnetic disturbance events on the Bulk-Power System equipment and the Bulk-Power
System as a whole.4

1

16 U.S.C. § 824o (2012).
18 C.F.R. § 39.5 (2014).
3
The Commission certified NERC as the electric reliability organization (“ERO”) in accordance with
Section 215 of the FPA on July 20, 2006. N. Am. Elec. Reliability Corp., 116 FERC ¶ 61,062 (2006) (“ERO
Certification Order”).
4
Order No. 779, Reliability Standards for Geomagnetic Disturbances, 143 FERC ¶ 61,147 (“Order No.
779”).
2

1

NERC requests that the Commission approve proposed Reliability Standard TPL-007-1
(Exhibit A) and the Definition and find that the proposed Reliability Standard and Definition are
just, reasonable, not unduly discriminatory or preferential, and in the public interest.5 NERC
also requests approval of: (i) the associated implementation plan (Exhibit B) for the proposed
Reliability Standard; and (ii) the associated Violation Risk Factors (“VRFs”) and Violation
Severity Levels (“VSLs”) (Exhibits A and G). The NERC Board of Trustees adopted proposed
Reliability Standard TPL-007-1 on December 17, 2014.
As required by Section 39.5(a)6 of the Commission’s regulations, this petition presents
the technical basis and purpose of proposed Reliability Standard TPL-007-1, a demonstration
that the proposed Reliability Standard meets the criteria identified by the Commission in Order
No. 6727 (Exhibit C), and a summary of the development history (Exhibit I).
I.

EXECUTIVE SUMMARY
Geomagnetic disturbances (“GMDs”) occur during solar storms when the sun ejects

charged particles directed toward the earth, and the magnetic field associated with these charged
particles interacts with the earth’s magnetic field. This interaction could cause geomagneticallyinduced currents (also known as “GICs”) to flow in an electric power system through
transmission lines and grounded transformer windings. GMDs can be of varying intensity, and
their impact on an electric power system is dependent on a number of factors, including where
the geomagnetic storm is located, the magnitude and direction of the geomagnetic fields, the

5

Unless otherwise designated, all capitalized terms shall have the meaning set forth in the Glossary of Terms
Used in NERC Reliability Standards, available at http://www.nerc.com/files/Glossary_of_Terms.pdf.
6
18 C.F.R. § 39.5(a) (2013).
7
The Commission specified in Order No. 672 certain general factors it would consider when assessing
whether a particular Reliability Standard is just and reasonable. See Rules Concerning Certification of the Electric
Reliability Organization; and Procedures for the Establishment, Approval, and Enforcement of Electric Reliability
Standards, Order No. 672, FERC Stats. & Regs. ¶ 31,204, at P 262, 321-37, order on reh’g, Order No. 672-A,
FERC Stats. & Regs. ¶ 31,212 (2006) (“Order No. 672”).

2

geomagnetic latitude of the electric power system, the local geology (i.e., electrical conductivity
of the ground), and the characteristics of the electric power system.
During a GMD event, GIC flow in transformers can substantially increase absorption of
reactive power and create harmonics, resulting in a risk of voltage instability or voltage collapse.
In some cases, GIC flow in power transformers can cause increased transformer hot-spot heating,
which can lead to equipment loss of life or damage. The science regarding the impacts of GMDs
on electric power systems is still evolving, and much remains to be learned about the unique
threat GMDs pose to the reliability of the Bulk-Power System. However, as the Commission
noted in Order No. 779, “while there is an ongoing debate as to how a severe GMD event will
most likely impact the Bulk-Power System, there is a general consensus that GMD events can
cause wide-spread blackouts due to voltage instability and subsequent voltage collapse, thus
disrupting the reliable operation of the Bulk-Power System.”8
Proposed Reliability Standard TPL-007-1, together with Commission-approved
Reliability Standard EOP-010-1, addresses the unique risks posed by a high-impact, lowfrequency GMD event on the reliable operation of the Bulk-Power System and is responsive to
the Commission’s concerns articulated in Order No. 779. As the Commission established in
Order No. 779, the proposed Reliability Standard "should include Requirements whose goal is to
prevent instability, uncontrolled separation, or cascading failures of the Bulk-Power system
when confronted with a benchmark GMD event."9 The proposed standard is responsive to this
directive by requiring owners and operators of the Bulk-Power System to conduct initial and ongoing assessments of the potential impact of a defined GMD event (referred to herein as the

8
9

Order No. 779 at P 24 (internal citation omitted).
Order No. 779 at P 84.

3

“Benchmark GMD Event”) on Bulk-Power System equipment and the Bulk-Power System as a
whole. The Benchmark GMD Event used to develop the proposed standard10 is based on a 1-in100 year frequency of occurrence, and is supported by rigorous technical analysis of modern
measurement data and publicly-available models. The proposed Benchmark GMD Event sets a
high benchmark for reliability, as it represents the most severe GMD event expected in a 100year period as determined by a statistical analysis of recorded geomagnetic data. Additionally,
the proposed standard specifies parameters for assessments that will identify impacts from this
Benchmark GMD Event and requires corrective action to protect against instability, uncontrolled
separation, and cascading failures of the Bulk-Power System.
The proposed Reliability Standard represents a significant milestone in NERC's ongoing
efforts to understand and address the unique reliability risks that high-impact, low-frequency
GMD events pose to the Bulk-Power System. The assessments and other actions required by the
proposed standard complement the Operating Plans, Processes, and Procedures required in the
Commission-approved EOP-010-1 Reliability Standard to address GMD impacts to the BulkPower System. Additionally, implementation of the proposed Reliability Standard will provide
opportunities to further mature the tools, models, and techniques for assessing potential impacts
of GMDs. Accordingly, for the reasons stated above and as discussed more fully herein, NERC
requests that the Commission approve proposed Reliability Standard TPL-007-1 and find that the
proposed Reliability Standard is just, reasonable, not unduly discriminatory or preferential, and
in the public interest.

10

See Order No. 779 at P 54 (“The Second Stage GMD Reliability Standard must identify what severity
GMD events (i.e., benchmark GMD events) that responsible entities will have to assess for potential impacts on the
Bulk-Power System.”)

4

II.

NOTICES AND COMMUNICATIONS
Notices and communications with respect to this filing may be addressed to the

following:11
Valerie Agnew*
Director of Standards
North American Electric Reliability Corporation
3353 Peachtree Road, N.E.
Suite 600, North Tower
Atlanta, GA 30326
(404) 446-2560
(404) 446-2595 – facsimile
[email protected]

Charles A. Berardesco*
Senior Vice President and General Counsel
Holly A. Hawkins*
Associate General Counsel
Lauren A. Perotti*
Counsel
North American Electric Reliability Corporation
1325 G Street, N.W., Suite 600
Washington, D.C. 20005
(202) 400-3000
(202) 644-8099 – facsimile
[email protected]
[email protected]
[email protected]
III.

BACKGROUND
In Order No. 779, the Commission directed NERC to develop a set of Reliability

Standards to address GMDs in two stages. In the first stage, NERC developed Reliability
Standard EOP-010-1, requiring owners and operators of the Bulk-Power System to develop and
implement operational procedures to mitigate the effects of GMDs consistent with the reliable
operation of the Bulk-Power System. The Commission approved Reliability Standard EOP-0101 in Order No. 797.12 In the second stage, the Commission directed NERC to develop one or
more proposed Reliability Standards that require owners and operators of the Bulk-Power
System to conduct initial and on-going vulnerability assessments of the potential impact of

11

Persons to be included on the Commission’s service list are identified by an asterisk. NERC respectfully
requests a waiver of Rule 203 of the Commission’s regulations, 18 C.F.R. § 385.203 (2014), to allow the inclusion
of more than two persons on the service list in this proceeding.
12
Order No. 797, Reliability Standard for Geomagnetic Disturbance Operations, 147 FERC ¶ 61,209, reh’g
denied, Order No. 797-A, 149 FERC ¶ 61,027 (2014) (“Order No. 797”).

5

benchmark GMD events on Bulk-Power System equipment and the Bulk-Power System as a
whole.13 This second stage is addressed in proposed Reliability Standard TPL-007-1.
The following background information is provided below: (a) an explanation of the
regulatory framework for NERC Reliability Standards; (b) an explanation of the NERC
Reliability Standards development process; and (c) the history of Project 2013-03, Geomagnetic
Disturbance Mitigation.
A.

Regulatory Framework

By enacting the Energy Policy Act of 2005,14 Congress entrusted the Commission with
the duties of approving and enforcing rules to ensure the reliability of the Nation’s Bulk-Power
System, and with the duties of certifying an ERO that would be charged with developing and
enforcing mandatory Reliability Standards, subject to Commission approval. Section 215(b)(1)15
of the FPA states that all users, owners, and operators of the Bulk-Power System in the United
States will be subject to Commission-approved Reliability Standards. Section 215(d)(5)16 of the
FPA authorizes the Commission to order the ERO to submit a new or modified Reliability
Standard. Section 39.5(a)17 of the Commission’s regulations requires the ERO to file with the
Commission for its approval each Reliability Standard that the ERO proposes should become
mandatory and enforceable in the United States, and each modification to a Reliability Standard
that the ERO proposes should be made effective.
The Commission has the regulatory responsibility to approve Reliability Standards that
protect the reliability of the Bulk-Power System and to ensure that such Reliability Standards are

13
14
15
16
17

Order No. 779 at PP 2, 67.
16 U.S.C. § 824o (2012).
Id. § 824o(b)(1).
Id. § 824o(d)(5).
18 C.F.R. § 39.5(a) (2014).

6

just, reasonable, not unduly discriminatory or preferential, and in the public interest. Pursuant to
Section 215(d)(2) of the FPA18 and Section 39.5(c)19 of the Commission’s regulations, the
Commission will give due weight to the technical expertise of the ERO with respect to the
content of a Reliability Standard.
B.

NERC Reliability Standards Development Process

The proposed Reliability Standard was developed in an open and fair manner and in
accordance with the Commission-approved Reliability Standard development process.20 NERC
develops Reliability Standards in accordance with Section 300 (Reliability Standards
Development) of its Rules of Procedure and the NERC Standard Processes Manual.21 In its ERO
Certification Order, the Commission found that NERC’s proposed rules provide for reasonable
notice and opportunity for public comment, due process, openness, and a balance of interests in
developing Reliability Standards and thus addresses certain of the criteria for approving
Reliability Standards.22 The development process is open to any person or entity with a
legitimate interest in the reliability of the Bulk-Power System. NERC considers the comments
of all stakeholders, and a vote of stakeholders and the NERC Board of Trustees is required to
approve a Reliability Standard before the Reliability Standard is submitted to the Commission
for approval.

18

16 U.S.C. § 824o(d)(2).
18 C.F.R. § 39.5(c)(1).
20
Rules Concerning Certification of the Electric Reliability Organization; and Procedures for the
Establishment, Approval, and Enforcement of Electric Reliability Standards, Order No. 672, FERC Stats. & Regs. ¶
31,204, order on reh’g, Order No. 672-A, FERC Stats. & Regs. ¶ 31,212 (2006).
21
The NERC Rules of Procedure are available at http://www.nerc.com/AboutNERC/Pages/Rules-ofProcedure.aspx. The NERC Standard Processes Manual is available at
http://www.nerc.com/comm/SC/Documents/Appendix_3A_StandardsProcessesManual.pdf.
22
116 FERC ¶ 61,062 at P 250 (2006).
19

7

C.

History of Project 2013-03, Geomagnetic Disturbance Mitigation

In June 2010, NERC identified that GMDs posed a serious threat to the reliable operation
of the Bulk-Power System and that addressing this issue required significant staff and industry
attention. Since that time, NERC has spent a substantial amount of time and effort working with
experts across the North American power industry, U.S. and Canadian government agencies,
transformer manufacturers, and other vendors to develop a scientifically sound understanding of
the potential risks GMDs may pose to reliability.
In early 2011, a NERC-sponsored GMD Task Force was formed to “develop a technical
white paper describing the evaluation of scenarios of potential GMD impacts, identifying key
bulk power system parameters under those scenario conditions, and evaluating potential
reliability implications of these incidents.”23 The GMD Task Force issued an interim report
evaluating the effects of GMDs on the Bulk-Power System in February 2012.24 Using an open
process involving leading experts from industry, government and private researchers, and
equipment and software vendors, the GMD Task Force has continued to support the development
of tools and methods for assessing and mitigating GMD impacts.
In October 2012, the Commission issued a Notice of Proposed Rulemaking (“NOPR”)
proposing to direct that NERC submit to the Commission for approval proposed Reliability
Standards that address the risks posed by GMDs to the reliable operation of the Bulk-Power
System.25 The NOPR stated that GMD vulnerabilities are not adequately addressed in the

23

NERC, Board of Trustees Minutes, Exhibit J, at 1 (Nov. 4, 2010), available at
http://www.nerc.com/docs/docs/bot/BOT-1110m-open-complete.pdf.
24
North American Electric Reliability Corp., 2012 Special Reliability Assessment Interim Report: Effects of
Geomagnetic Disturbances on the Bulk Power System (February 2012) (“2012 NERC Interim GMD Report”),
available at http://www.nerc.com/files/2012GMD.pdf.
25
Reliability Standards for Geomagnetic Disturbances, Notice of Proposed Rulemaking, 77 Fed. Reg. 64,935
(Oct. 24, 2012), 141 FERC ¶ 61,045 (2012) (“NOPR”).

8

existing Reliability Standards, and that this therefore constitutes a reliability gap — because
GMD events can cause the Bulk-Power System to collapse suddenly and can potentially damage
equipment on the Bulk-Power System.26
In May 2013, the Commission issued Order No. 779 directing NERC to develop
proposed Reliability Standards addressing GMD events in two stages, as explained above. In
June 2014, the Commission issued Order No. 797, approving the first stage GMD Reliability
Standard EOP-010-1. Reliability Standard EOP-010-1 mitigates the effects of GMDs on the
Bulk-Power System by requiring applicable entities to implement Operating Plans and Operating
Procedures or Processes. This petition addresses the second stage GMD Reliability Standard.
Proposed Reliability Standard TPL-007-1 is based on sound research and industryleading engineering approaches. The standard drafting team that developed the proposed
standard includes engineers, planners, and operators that are at the forefront of the industry's
GMD activities, including an experienced representative from Canada, as well as a leading space
weather researcher from NASA.27 Several members of the standard drafting team are also
leaders of the NERC GMD Task Force. Through the NERC GMD Task Force, the standard
drafting team has worked collaboratively with scientific and technical organizations, equipment
manufacturers, software vendors, and colleagues throughout the industry to develop state-of-theart guidelines, modeling approaches, and technical resources that underpin the proposed
Reliability Standard.

26

Id. at P 4.
The standard drafting team roster for Project 2013-03, Geomagnetic Disturbance Mitigation is attached as
Exhibit J to this petition.

27

9

IV.

JUSTIFICATION FOR APPROVAL
As discussed in detail in Exhibit C, proposed Reliability Standard TPL-007-1—

Transmission System Planned Performance for Geomagnetic Disturbance Events addresses the
Commission’s criteria in Order No. 672 and is just, reasonable, not unduly discriminatory or
preferential, and in the public interest. As described more fully herein and in Exhibit C, the
proposed Reliability Standard contains significant reliability benefits for the Bulk-Power System
and addresses the directives and concerns identified by the Commission in Order No. 779.
The purpose of proposed Reliability Standard TPL-007-1 is to establish requirements for
planned Transmission system performance during GMD events. The provisions of the proposed
standard raise the level of preparedness among applicable entities by requiring these entities to
plan for the reliable operation of the Bulk-Power System during the Benchmark GMD Event - a
severe, 1-in-100 year GMD event.
The proposed standard includes the proposed definition of GMD Vulnerability
Assessment. GMD Vulnerability Assessments provide the framework for evaluating potential
impacts of the Benchmark GMD Event on Bulk-Power System equipment and the Bulk-Power
System as a whole. Using a planning approach, the proposed Reliability Standard includes
requirements for coordinating responsibilities among applicable entities, developing and
maintaining models, establishing performance criteria and assessing performance, exchanging
relevant information necessary to coordinate the actions of applicable entities, and developing
Corrective Action Plans to address performance deficiencies.
This section of the petition addresses: (i) the description of the proposed Definition; (ii)
the applicability of proposed Reliability Standard TPL-007-1; (iii) the description and technical
basis for the Benchmark GMD Event; (iv) the description and technical basis for thermal impact
assessments for power transformers; (v) the description of the proposed Requirements; and (vi)
10

the description of the proposed implementation plan. This section also provides a brief summary
of how proposed Reliability Standard TPL-007-1 addresses the Commission’s directives from
Order No. 779 and concludes with a discussion of the enforceability of the proposed standard.
A.

Proposed Definition of “Geomagnetic Disturbance Vulnerability Assessment
or “GMD Vulnerability Assessment"

The following Definition is proposed for inclusion in the Glossary of Terms Used in
NERC Reliability Standards:
Geomagnetic Disturbance Vulnerability Assessment or GMD
Vulnerability Assessment: Documented evaluation of potential
susceptibility to voltage collapse, Cascading, or localized damage of
equipment due to geomagnetic disturbances.
The GMD Vulnerability Assessment is an integral part of the proposed Reliability
Standard and provides the framework for evaluating potential impacts of the Benchmark GMD
Event on Bulk-Power System equipment and the Bulk-Power System as a whole.28 It also
provides the means to allow for the identification of “facilities most at-risk from severe
geomagnetic disturbance” in accordance with Order No. 779.29
Figure 1 below provides a graphical depiction of the GMD Vulnerability Assessment
process. A summary description follows.

28

See Order No. 779 at P 67. See also Order No. 779 at P 24 (“[T]here is a general consensus that GMD
events can cause wide-spread blackouts due to voltage instability and subsequent voltage collapse, thus disrupting
the reliable operation of the Bulk-Power System.”)
29
Order No. 779 at P 51.

11

Figure 1.

GMD Vulnerability Assessment Process

In the GMD Vulnerability Assessment process outlined in the diagram above, the
transmission system GIC flows are calculated by applicable Transmission Planners and Planning
Coordinators for the Benchmark GMD Event using GIC system models. These models represent
the direct current (dc) characteristics of the transmission system, including applicable power
transformers, transmission lines, GIC reduction or blocking devices, and reactive power
compensation devices.30 The GIC flow information at each applicable power transformer is used
with power transformer electrical models to determine the maximum reactive power losses; the
maximum reactive power losses are applied to the power flow analysis required by the GMD
Vulnerability Assessment. Additionally, using transformer thermal models and GIC flow
information at each applicable power transformer, Transmission Owners and Generator Owners
conduct transformer thermal impact assessments to determine the additional hot-spot heating that
could be caused by the Benchmark GMD Event. Results of the power flow analysis and
transformer thermal impact assessments are evaluated according to assessment criteria. When

30

NERC GMD Task Force, Application Guide for Computing Geomagnetically-Induced Current in the BulkPower System at 18-25 (December 2013), available at
http://www.nerc.com/comm/PC/Geomagnetic%20Disturbance%20Task%20Force%20GMDTF%202013/GIC%20A
pplication%20Guide%202013_approved.pdf. (“GIC Application Guide”)

12

mitigation measures are determined to be necessary, steps in the GMD Vulnerability Assessment
process are repeated to recalculate GIC flows and reevaluate transmission system performance.
The Geomagnetic Disturbance Planning Guide, developed by the NERC GMD Task Force in
2013, provides detailed technical guidance to support GMD-specific studies that are used in the
GMD Vulnerability Assessment process.31
As described more fully below, proposed Reliability Standard TPL-007-1 contains
requirements to develop the models, studies, and assessments necessary to build a picture of
overall GMD vulnerability and identify where mitigation measures may be necessary.
B.
Applicability of Proposed Reliability Standard TPL-007-1 – Transmission
System Planned Performance for Geomagnetic Disturbance Events
Proposed Reliability Standard TPL-007-1 is applicable to: (1) Planning Coordinators with
a planning area that includes a power transformer(s) with a high side, wye-grounded winding
with terminal voltage greater than 200 kV; (2) Transmission Planners with a planning area that
includes a power transformer(s) with a high side, wye-grounded winding with terminal voltage
greater than 200 kV; (3) Transmission Owners that own a Facility or Facilities that include a
power transformer(s) with a high side, wye-grounded winding with terminal voltage greater than
200 kV; and (4) Generator Owners that own a Facility or Facilities that include a power
transformer(s) with a high side, wye-grounded winding with terminal voltage greater than 200
kV.32

31

NERC GMD Task Force, Geomagnetic Disturbance Planning Guide (Dec. 2013), available at
http://www.nerc.com/comm/PC/Geomagnetic%20Disturbance%20Task%20Force%20GMDTF%202013/GMD%20
Planning%20Guide_approved.pdf (“GMD Planning Guide”).
32
A power transformer with a “high side wye-grounded winding” refers to a power transformer with
windings on the high voltage side that are connected in a wye configuration and have a grounded neutral connection.

13

The applicability section of proposed Reliability Standard TPL-007-1 is consistent with
Order No. No. 779 and Order No. 797. As the Commission noted in Order No. 779, “[b]ecause
many Bulk-Power System transformers are grounded, the GIC appears as electrical current to the
Bulk-Power System and flows through the ground connection and conductors, such as
transformers and transmission lines.”33 The applicability of proposed Reliability Standard TPL007-1 recognizes the technical considerations of the impact of a GMD event on the Bulk-Power
System.
Proposed Reliability Standard TPL-007-1 complements the stage one GMD Reliability
Standard, EOP-010-1, which is applicable to Reliability Coordinators and those Transmission
Operators with a Transmission Operator Area that includes a power transformer with a high side
wye-grounded winding with terminal voltage greater than 200 kV. EOP-010-1 requires these
entities to implement Operating Plans and Operating Procedures or Processes to mitigate the
effects of GMDs on the Bulk-Power System.
The standard drafting team determined that a voltage threshold of greater than 200 kV for
proposed Reliability Standard TPL-007-1 is appropriate because the effect of GICs in networks
less than 200 kV would have a negligible impact on the reliability of the interconnected
transmission system. This finding is supported by operating experience and the preponderance
of peer-reviewed studies on GMD effects34 and is consistent with the scope and purpose of both
the proposed Reliability Standard and the Commission-approved EOP-010-1 Reliability
Standard.

33

Order No. 779 at P 6 (citing 2012 NERC Interim GMD Report at ii).
See Petition of the North American Electric Reliability Corporation for Approval of Proposed Reliability
Standard EOP-010-1, RM14-1-000 (Nov. 14, 2013) at Exhibit D.

34

14

C.

The Benchmark GMD Event

Proposed Reliability Standard TPL-007-1 requires applicable entities to conduct initial
and on-going assessments of the potential impact of the Benchmark GMD Event on Bulk-Power
System equipment and the Bulk-Power System as a whole. The purpose of the Benchmark
GMD Event is to provide a defined event for assessing system performance during a low
probability, high magnitude GMD event as required by the proposed TPL-007-1 Reliability
Standard. The Benchmark GMD Event defines the geoelectric field values used to compute GIC
flows that are needed to conduct a GMD Vulnerability Assessment. As the Commission noted in
Order No. 779, the Benchmark GMD Event must be technically justified to “define the scope of
the Second Stage GMD Reliability Standards (i.e., responsible entities should not be required to
assess GMD events more severe than the benchmark GMD events).”35 The proposed Benchmark
GMD Event is technically supported by modern measurement data and publicly-available
models. Further, the proposed Benchmark GMD Event sets a high benchmark for reliability, as
it represents the most severe GMD event expected in a 100-year period as determined by a
statistical analysis of recorded geomagnetic data.
As discussed below, the proposed Benchmark GMD Event is described in terms that can
be directly applied to the performance of GMD Vulnerability Assessments required by proposed
Reliability Standard TPL-007-1. Further, the proposed Benchmark GMD Event supports the
assessment of known GMD-related vulnerabilities with the potential to impact the reliable
operation of the Bulk-Power System, such increased reactive power consumption in power
transformers, loss of reactive power sources, and increased transformer hot-spot heating. The
Benchmark Geomagnetic Disturbance Event Description white paper included as Exhibit D

35

Order No. 779 at P 2.

15

provides additional description of the parameters of the Benchmark GMD Event, explains the
technical details that led to the selection of these parameters, and demonstrates how they should
be applied to obtain entity-specific values.
Thus, the proposed Benchmark GMD Event addresses the Commission’s directive to
specify what severity GMD event an entity must assess for potential impacts on the Bulk-Power
System and defines the scope for proposed Reliability Standard TPL-007-1.
1.
The Proposed Benchmark GMD Event Sets a High Benchmark for
Reliability
The proposed Benchmark GMD Event sets a high benchmark for reliability, as it
represents the most severe GMD event expected in a 100-year period as determined by a
statistical analysis of recorded geomagnetic data. The Benchmark GMD Event used to develop
the proposed standard is based on a 1-in-100 year frequency of occurrence, which is a
conservative planning criterion for electric power systems.36 A 1-in-100 year occurrence rate
addresses risks from a GMD event on the order of the March 1989 GMD event, which has
caused known impacts to the Bulk-Power System, and reasonably protects against impacts from
more extreme GMD events.
The March 1989 GMD event, which impacted the North American Bulk-Power System
by causing a blackout in Quebec,37 is considered to be a 1-in-50 year GMD event and one of the
strongest for which detailed and accurate records are available.38 The Carrington Event of 1859
was stronger than the March 1989 GMD event, but limited information is available to accurately

36

For additional information, see Benchmark Geomagnetic Disturbance Event Description (Exhibit D) at 5
and Appendix I.
37
For more information about the March 1989 GMD event, see 2012 NERC Interim GMD Report at i.
38
See Jeffrey J. Love, Credible Occurrence Probabilities for Extreme Geophysical Events: Earthquakes,
Volcanic Eruptions, Magnetic Storms, GEOPHYSICAL RES. LETTERS (May 2012) (hereinafter “Love (2012)”).

16

describe this event.39 A Carrington-type event is considered to be a 1-in-150 year GMD event,
but uncertainty in the occurrence rate is even greater than that for the March 1989 GMD event.40
Thus, the selection of a 1-in-100 year occurrence rate for the Benchmark GMD Event provides a
high level of assurance that the Bulk-Power System is planned for reliable operations during a
severe GMD event.
The Benchmark GMD Event is technically-supported by the use of modern measurement
data and statistical techniques. The Benchmark GMD Event expands on work conducted by the
NERC GMD Task Force in which 1-in-100 year geoelectric field amplitudes were calculated
from a well-known source of dense high-resolution geomagnetic data commonly used in space
weather research.41 This approach was adapted to develop the Benchmark GMD Event which
supports, through the GMD Vulnerability Assessments required by proposed Reliability
Standard TPL-007-1, the identification of GMD impacts with the potential to cause "instability,
uncontrolled separation, or cascading failures of the Bulk-Power System.”42 Additional extreme
value analysis was performed to determine that the geoelectric field associated with the proposed
Benchmark GMD Event exceeds the 95% confidence bound, which indicates that the likelihood
of a GMD event exceeding the proposed benchmark during a 100-year period is low.

39

This is the largest recorded GMD event, named after the British astronomer Richard Carrington.
See id.
41
A. Pulkkinen et al., Generation of 100-year Geomagnetically Induced Current Scenarios, SPACE WEATHER
(2012); see also 2012 NERC Interim GMD Report at 20-23.
42
The Commission indicated in Order No 779 that the proposed Reliability Standard should include
"Requirements whose goal is to prevent instability, uncontrolled separation, or cascading failures of the Bulk-Power
System when confronted with a benchmark GMD event." Order No. 779 at P. 84. Appendix I to the Benchmark
Geomagnetic Disturbance Event Description white paper (Exhibit D) describes how the Benchmark GMD Event
was developed to support assessment of these impacts.
40

17

2.
The Benchmark GMD Event Can be Directly Applied to the
Performance of GMD Vulnerability Assessments
The proposed Benchmark GMD Event is described by parameters that are usable by
applicable entities in conducting their GMD Vulnerability Assessments. While there are a
variety of measurements and indices that can be used to describe GMD conditions,43 assessment
of GMD effects on an electric power system requires the calculation of GICs that result from the
geoelectric fields produced by the earth’s varying magnetic field during a GMD event. The
geoelectric field produced during a GMD event is dependent upon the geomagnetic latitude and
earth conductivity where the electric power system is located and is the direct physical parameter
leading to the creation of GICs, as described in technical references.44 Consequently, the
proposed Benchmark GMD Event is described in terms of the geoelectric field (V/km) for use by
applicable entities in conducting GMD Vulnerability Assessments.
Although the Benchmark GMD Event is described in proposed Reliability Standard TPL007-1 as a single event, it includes several components within its framework for assessing GMD
vulnerabilities. The Benchmark GMD Event includes technically-justified scaling factors to
enable applicable entities to tailor the geoelectric field to their specific location for conducting
GMD Vulnerability Assessments. This accounts for differences in the intensity of a GMD event
due to geographical considerations, such as geomagnetic latitude and local earth conductivity.45
The geomagnetic latitude scaling factor is based on modern global scientific observations for

43

These include the A index, K index, and G scales that are used by space weather monitoring and
forecasting organizations to describe geomagnetic storm severity and the disturbance storm time (Dst) index
measuring the amplitude of the main phase disturbance for a magnetic storm. Many of these indices were originally
designed for scientific or research purposes.
44
See generally GIC Application Guide.
45
See Benchmark Geomagnetic Disturbance Event Description (Exhibit D).

18

major storms since late 1980s.46 Scaling factors for earth conductivity take into account that the
induced geoelectric field depends on local earth conductivity, and that different parts of the
continent have different earth conductivity and deep earth structure. The Benchmark GMD
Event includes default scaling factors for earth conductivity based on publicly-available earth
models. These technically-justified scaling factors allow the applicable entities of proposed
Reliability Standard TPL-007-1 to perform GMD Vulnerability Assessments according to entityspecific criteria.47
3.
The Proposed Benchmark GMD Event Includes the Necessary
Parameters to Support Assessment of Known GMD Related Vulnerabilities

The Benchmark GMD Event also includes the parameters necessary to support
assessment of various known GMD-related vulnerabilities that have the potential to impact the
reliable operation of the Bulk-Power System. GMD events have the potential to produce electric
power system impacts, such as increased reactive power consumption in power transformers,
loss of reactive power sources, and increased transformer hot-spot heating. For the purpose of
conducting GMD Vulnerability Assessments, some impacts, such as reactive power losses,
should be considered as having a nearly-instantaneous effect on an electric power system. Other
impacts, like increased transformer hot spot heating, affect an electric power system over longer
periods of time during a GMD event, and thus should not be assumed to occur instantaneously.
To address these considerations, the proposed Benchmark GMD Event includes both: (i) a peak

46

The studied storms reveal that the propagation of auroral boundaries stops at about 50 degrees of
geomagnetic latitude. This is a repeating feature of the geospace system under strong solar driving conditions and
scaling over the band between 40-60 degrees of geomagnetic latitude. See C. Ngwira and A. Pulkinnen et al.,
Extended Study of Extreme Geoelectric Field Event Scenarios for Geomagnetically Induced Current Applications,
11 SPACE WEATHER 121 (2013)).
47
In Order No. 779, the Commission recognized the need for tailored assessments based on "geographic
location and geology" and stated the expectation that "vulnerability assessments would be based on uniform criteria
(e.g., geographic location and geology) but the values for such criteria would be entity-specific." Order No. 779 at P
70.

19

geoelectric field magnitude for assessing near-instantaneous voltage impacts, as discussed
previously; and (ii) a waveshape for calculating a GIC time-series that is used in assessing
thermal impacts in power transformers, as discussed in more detail below.
An analysis of the high resolution magnetometer data from several GMD events, as
shown in the Benchmark Geomagnetic Disturbance Event Description white paper (Exhibit D),
indicates that the March 1989 GMD event provides a conservative worst-case waveshape for
conducting transformer thermal impact assessments. Consequently, the Benchmark GMD Event
waveshape is based on magnetometer data of the March 1989 GMD event recorded by the
Ottawa geomagnetic observatory.48 To conduct a transformer thermal assessment, an applicable
Transmission Owner or Generator Owner uses GIC flows based on the March 1989 GMD event
waveshape, magnified to the statistically-derived 1-in-100 year geoelectric field strength. Thus,
the Benchmark GMD Event provides a 1-in-100 year benchmark for assessing GMD impacts to
Bulk-Power System equipment.
4.
Additional Benchmark GMD Event Considerations in the Standards
Development Process

Past reports and ongoing scientific research reflect varying perspectives on the potential
severity of GMD events. As the Commission recognized in Order No. 779, there is no consensus
on benchmark GMD events for assessing the vulnerability of the Bulk-Power System.49
Accordingly, the proposed Benchmark GMD Event was evaluated throughout the development
of the proposed standard, resulting in a benchmark supported by rigorous technical analysis of

48

In the Benchmark Geomagnetic Disturbance Event Description white paper (Exhibit D), an analysis of
available GMD events with 10-second magnetic data was conducted to determine that the March 1989 GMD event
represented the most conservative selection. See id. at 15-16.
49
See Order No. 779 at P 71 ("[T]here is currently no consensus on benchmark GMD events, and the
Commission does not identify specific benchmark GMD events for NERC to adopt. Instead, this issue should be
considered in the NERC standards development process so that any benchmark GMD events proposed by NERC
have a strong technical basis.").

20

modern measurement data and publicly-available models. The use of modern measurement data
and statistical techniques provides for a state-of-the-art Benchmark GMD Event for use in GMD
Vulnerability Assessments required by proposed Reliability Standard TPL-007-1.
As discussed above, the proposed Benchmark GMD Event is more intense than the
March 1989 GMD event to appropriately address the risks of a high-impact, low frequency
GMD event.50 The standard drafting team also examined other historical GMD events in
developing the proposed Benchmark GMD Event, some of which are described below.
Geomagnetic Storm of 1921
Some reports examining the effects of GMD events on the power system suggested that
the geomagnetic storm of 1921 is a 1-in-100-year event. These reports described the potential
impacts a GMD event of this magnitude could have on the grid.51 After much consideration, the
standard drafting team determined, that with limited direct observations of the magnetic fields, it
was not possible to include the 1921 event in a rigorous determination of the 1-in-100-year
Benchmark GMD Event characteristics. Without this data, it was also not possible to perform a
more-detailed analysis of the impacts of the 1921 event on the modern electric power system.52

50

Some estimate the March 1989 GMD Event is a 1-in-50 year event. See Love (2012), supra n. 38. The
Benchmark GMD Event magnifies the March 1989 GMD event waveshape to the statistically-derived 1-in-100 year
geoelectric field strength to provide a 1-in-100 year intensity.
51
See Oak Ridge National Laboratory, FERC EMP-GIC Metatech Report Meta-R-319 at 3-22 (January
2010), available at http://web.ornl.gov/sci/ees/etsd/pes/pubs/ferc_Meta-R-319.pdf (“Meta R-319”); see also
National Research Council of the National Academies, Severe Space Weather Events – Understanding Societal and
Economic Impacts, a Workshop Report at 3, 77 (2008), available at http://www.nap.edu/catalog/12507/severespace-weather-events--understanding-societal-and-economic-impacts.
52
The 2011 JASON Summer Study sponsored by U.S. Department of Homeland Security reported that the
authors were "not convinced that the worst-case scenario [of Meta-R-319] is plausible." See JASON, Impacts of
Severe Space Weather on the Electric Grid, JSR-11-320 at 2 (2011).

21

Carrington Event of 1859
Another extreme GMD event that has been considered by some researchers as a basis for
risk assessment is the Carrington Event of 1859. Like the 1921 GMD event, high-quality
geomagnetic field data are not available that would allow direct determination of the geoelectric
fields experienced during the Carrington Event. Research is being conducted to examine the
capability for complex dynamic space weather prediction models to determine the geoelectric
fields produced by Carrington-like space weather conditions.53 However, at present, these
efforts are a basic research endeavor aimed at assessing performance of the dynamic space
weather prediction models. Furthermore, the occurrence rate of a Carrington-type GMD event is
uncertain, but it is estimated to be a 1-in-150 year event, as discussed previously.54
July 2012 Coronal Mass Ejection
Some researchers have examined, through simulations, the potential geomagnetic effects
of a powerful coronal mass ejection observed by NASA spacecraft in July 2012.55 Since the July
2012 coronal mass ejection did not impact the earth, research analyses require relying on space
science models for estimating its geomagnetic impact. Due to the complex nature of the space
weather phenomena and relatively immature state of modern space science models, dynamic
model-based assessments contain inherent uncertainties that are not always well known. While
events such as the July 2012 coronal mass ejection provide a valuable research opportunity for
the space weather community to improve its space weather prediction modeling capabilities, the

53

C. Ngwira et al., Modeling Extreme "Carrington-type" Space Weather Events Using Three-dimensional
Global MHD Simulations, 119 J. OF GEOPHYSICAL RES.: SPACE PHYSICS 4456 (2014)).
54
See Love (2012), supra n. 38.
55
See C. Ngwira et al., Simulation of the 23 July 2012 Extreme Space Weather Event: What if This Extremely
Rare CME was Earth Directed?, 11 SPACE WEATHER 671 at 677 (2013) (concluding that "had the 23 July CME hit
Earth, there is a possibility that it could have produced comparable or slightly larger geomagnetically induced
electric fields to those produced by previously observed Earth directed events such as the March 1989 storm or the
Halloween 2003 storms."); see also D.N. Baker et al., A Major Solar Eruptive Event in July 2012: Defining Extreme
Space Weather Scenarios, 11 SPACE WEATHER 585 (2013).

22

standard drafting team determined that observed geomagnetic data is more appropriate for direct
application to the Benchmark GMD Event description and the proposed Reliability Standard.

Given the varying nature and degree of scientific uncertainty in the events described
above, the proposed Reliability Standard and accompanying Benchmark GMD Event incorporate
rigorous technical analysis that is representative of the complex nature of space weather
phenomena, and therefore reflects a balanced and practical approach in the proposed TPL-007-1
Reliability Standard.
D.

Transformer Thermal Impact Assessment

Large power transformers connected to the high voltage and extra high voltage
Transmission systems can experience both increased winding and structural hot spot heating as a
result of GIC flow during GMD events. Proposed Reliability Standard TPL-007-1 requires
owners of such transformers to conduct thermal analyses of their transformers to determine if the
transformers would be able to withstand the thermal effects associated with the Benchmark
GMD Event. The Transformer Thermal Impact Assessment White Paper (Exhibit E) discusses
methods that can be employed to conduct such analyses, including example calculations.
Transformers are exempt from the thermal impact assessment requirement included in the
proposed standard if the maximum effective GIC in the transformer is less than 75 A per phase
during the Benchmark GMD Event as determined by an analysis of the system.56 Based on
available power transformer measurement data and as described in the Screening Criterion for
Transformer Thermal Impact Assessment white paper (Exhibit F), transformers with an

56

See Screening Criterion for Transformer Thermal Impact Assessment (Exhibit F) for technical justification
of the thermal impact screening criterion. The 75 A per phase threshold is based on the Benchmark GMD Event
waveshape and resulting GIC time series in order to identify those applicable transformers that may experience
excessive hot spot heating during the Benchmark GMD Event. The criterion should not be interpreted as a
continuous value of 75 A per phase effective GIC.

23

effective GIC of less than 75 A per phase during the Benchmark GMD Event are unlikely to
exceed known temperature limits established by technical organizations. To provide an added
measure of conservatism, the 75 A per phase threshold, although derived from measurements of
single-phase units, is applicable to transformers with all core types (e.g., three-limb, threephase).
E.
Requirements in Proposed Reliability Standard TPL-007-1 – Transmission
System Planned Performance for Geomagnetic Disturbance Events
The purpose of proposed Reliability Standard TPL-007-1 is to establish requirements for
Transmission system planned performance during GMD events. The proposed Reliability
Standard consists of seven Requirements, Table 1 – Steady State Planning Events, and
Attachment 1 – Calculating Geoelectric Fields for the Benchmark GMD Event. Table 1 sets
forth requirements for System steady state performance. Attachment 1 explains how to calculate
geoelectric fields to establish the Benchmark GMD Event.
Proposed Requirement R1 requires Planning Coordinators, in conjunction with
Transmission Planner(s), to identify the 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 GMD Vulnerability Assessment(s).
Proposed Requirements R2, R3, R4, R5, and R7 therefore refer to the “responsible entity, as
determined by Requirement R1,” when identifying which applicable Planning Coordinators or
Transmission Planners are responsible for maintaining models and performing the necessary
study or studies.
Proposed Requirement R2 is intended to ensure that the responsible entities maintain
models for performing the studies needed to complete GMD Vulnerability Assessment(s)
required by proposed Requirement R4. Proposed Requirement R3 requires the responsible
24

entities to have criteria for acceptable System steady state voltage performance during a
Benchmark GMD Event.
Proposed Requirement R4 requires the responsible entities to complete a GMD
Vulnerability Assessment of the Near-Term Transmission Planning Horizon once every 60
calendar months.
Proposed Requirement R5 requires the responsible entities to provide GIC flow
information to Transmission Owners and Generator Owners that own a Bulk Electric System
(BES) power transformer in the planning area. This information is necessary for applicable
Transmission Owners and Generator Owners to conduct the thermal impact assessments required
by proposed Requirement R6. Proposed Requirement R6 requires applicable Transmission
Owners and Generator Owners to conduct thermal impact assessments where the maximum
effective GIC value provided in proposed Requirement R5, Part 5.1 is 75 A per phase or greater.
Proposed Requirement R7 requires the responsible entities to develop a Corrective
Action Plan when its GMD Vulnerability Assessment indicates that its System does not meet the
performance requirements of Table 1 – Steady State Planning Events. The Corrective Action
Plan must address how the performance requirements will be met, must list the specific
deficiencies and associated actions that are necessary to achieve performance, and must set forth
a timetable for completion.
Collectively, the proposed Requirements, Table 1, and Attachment 1 address the
Commission’s directives in Order No. 779 and are intended to establish requirements for
Transmission system planned performance during GMD events. Provided below is a
justification of the proposed Reliability Standard on a requirement-by-requirement basis.

25

Proposed Requirements

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 GMD
Vulnerability Assessment(s).

Proposed Requirement R1 requires applicable Planning Coordinators, in conjunction with
Transmission Planner(s), to identify the 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 GMD Vulnerability Assessment(s). This
determination sets forth the roles and responsibilities for applicable Planning Coordinators and
Transmission Planners for Requirements R2 through R5 and R7 of proposed Reliability Standard
TPL-007-1 and is designed to allow for differences in regional organizations and to provide
flexibility. 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). Proposed Requirement R1 ensures that the responsibilities within a
planning area are clearly articulated and understood, particularly where there are joint
responsibilities.

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 GMD Vulnerability
Assessment(s).

Proposed Requirement R2 builds upon Requirement R1, and it is intended to ensure that
the responsible entities maintain System models and GIC System models for performing the
studies needed to complete GMD Vulnerability Assessment(s) as required in proposed
26

Requirement R4. A GMD Vulnerability Assessment requires a GIC System model to calculate
GIC flow, which is then used to determine transformer Reactive Power absorption and
transformer thermal response.
The GIC System model includes all power transformer(s) in the planning area with a high
side, wye-grounded winding with terminal voltage greater than 200 kV. Technical guidance for
developing the GIC System model is provided in the GIC Application Guide.
The System model specified in proposed 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. Steady state power flow analysis is required by the
GMD Vulnerability Assessment, as specified in proposed Requirement R4.

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 event described in Attachment 1.

Proposed Requirement R3 specifies that the responsible entity shall establish the System
steady state voltage performance criteria for use in the GMD Vulnerability Assessment. Steady
state voltage limits are an example of System steady state performance criteria. Proposed
Requirement R3 provides flexibility for development of more sophisticated methods of
determining voltage stability.

27

R4.

Each responsible entity, as determined in Requirement R1, shall complete a GMD
Vulnerability Assessment of the Near-Term Transmission Planning Horizon once
every 60 calendar months. This 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.
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 in Table 1.
4.3.
The GMD Vulnerability Assessment shall be provided within 90 calendar
days of completion to the responsible entity’s Reliability Coordinator,
adjacent Planning Coordinators, adjacent Transmission Planners, and to any
functional entity that submits a written request and has a reliability-related
need.
4.3.1. If a recipient of the 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.

Proposed Requirement R4 requires the responsible entities (as determined in
Requirement R1) to complete a GMD Vulnerability Assessment of the Near-Term Transmission
Planning Horizon once every 60 calendar months. The “Near Term Transmission Planning
Horizon” is defined in the Glossary of Terms Used in NERC Reliability Standards as “The
transmission planning period that covers Year One through five.”57 Requirement R4 Part 4.1
specifies that studies must be conducted for both On-Peak Load and Off-Peak Load conditions in
order to account for a range of System Reactive Power resources in the assessment. Table 1 –
Steady State Planning Events establishes uniform performance criteria and assessment details.
Because some devices that are susceptible to harmonic impacts may affect System steady state

57

“Year One” is defined in the Glossary of Terms Used in NERC Reliability Standards as “The first twelve
month period that a Planning Coordinator or a Transmission Planner is responsible for assessing. For an assessment
started in a given calendar year, Year One includes the forecasted peak Load period for one of the following two
calendar years. For example, if a Planning Assessment was started in 2011, then Year One includes the forecasted
peak Load period for either 2012 or 2013.”

28

performance, Table 1 requires responsible entities to remove such devices from the analysis
when assessing System performance. Proposed Requirement R4 establishes consistent
parameters for the responsible entities to conduct initial and on-going GMD Vulnerability
Assessments that meet the directives in Order No. 779.58

R5.

Each responsible entity, as determined in Requirement R1, shall provide GIC flow
information to be used for the transformer thermal impact assessment 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:
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.

Proposed Requirement R5 is intended to ensure that Transmission Owners and Generator
Owners can access GIC flow information in order to perform the transformer thermal impact
assessment required in proposed Requirement R6. GIC information should be provided in
accordance with proposed 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 GIC flow information
specified in Part 5.1 and Part 5.2 of proposed Requirement R5 support various methods for

58

Order No. 779 directed that "[e]ach responsible entity under the Second Stage GMD Reliability Standards
would then be required to assess its vulnerability to the benchmark GMD events consistent with the five assessment
parameters identified in the NOPR and adopted in this Final Rule." Order No. 779 at P. 67.

29

performing transformer thermal impact assessments. These methods are described in the
Transformer Thermal Impact Assessment White Paper, included as Exhibit E to this petition.

R6.

Each Transmission Owner and Generator Owner shall conduct a 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 thermal impact assessment shall:
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.

Proposed Requirement R6 requires Transmission Owners and Generator Owners to
conduct thermal impact assessments for their solely and jointly-owned power transformers with a
high side, wye-grounded winding with terminal voltage greater than 200 kV where the maximum
effective GIC value for the worst case geoelectric field orientation for the Benchmark GMD
Event described in Attachment 1 is 75 A per phase or greater. Transformers are exempt from the
thermal impact assessment requirement if the maximum effective GIC in the transformer is less
than 75 A per phase during the Benchmark GMD Event as determined by an analysis of the
system. Based on available power transformer measurement data, transformers with an effective
GIC of less than 75 A per phase during the Benchmark GMD Event are unlikely to exceed
known temperature limits established by technical organizations. Additional information is
available in the Screening Criterion for Transformer Thermal Impact Assessment white paper,
included as Exhibit F to this petition.
Thermal impact assessments are provided to the responsible entity, as determined in
proposed Requirement R1, so that identified issues can be included in the GMD Vulnerability
Assessment (Requirement R4) and the Corrective Action Plan (Requirement R7) as necessary.
30

Thermal impact assessments of non-BES transformers are not required because those
transformers do not pose a risk of Bulk-Power System instability, uncontrolled separation, or
Cascading.

R7.

Each responsible entity, as determined in Requirement R1, that concludes, through
the GMD Vulnerability Assessment conducted in Requirement R4, that their
System does not meet the performance requirements of Table 1 shall develop a
Corrective Action Plan addressing how the performance requirements will be met.
The Corrective Action Plan shall:
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 Special
Protection Systems.
• Use of Operating Procedures, specifying how long they will be needed as
part of the Corrective Action Plan.
• Use of Demand-Side Management, new technologies, or other initiatives.
7.2. Be 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.
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.

When a responsible entity’s GMD Vulnerability Assessment does not meet the
performance requirements of Table 1 – Steady State Planning Events, proposed Requirement R7
mandates that it must develop a Corrective Action Plan addressing how the performance
requirements of Table 1 will be met. A “Corrective Action Plan” is defined in the Glossary of
Terms Used in NERC Reliability Standards as “[a] list of actions and an associated timetable for
implementation to remedy a specific problem.” The Corrective Action Plan must list the System
31

deficiencies and associated actions needed to achieve performance as set forth in Section 7.1 of
proposed Requirement R7. To ensure accountability, the responsible entities must review these
deficiencies in subsequent GMD Vulnerability Assessments until such time that the System
meets the performance requirements of Table 1. Proposed Requirement R7 is technology-neutral
and provides flexibility for the responsible entities to select appropriate mitigation strategies,
subject to the vulnerabilities identified in the assessments and as supported by technical
guidance. These mitigating strategies may include installation of hardware (e.g., GIC blocking
or monitoring devices), equipment upgrades, training, or enhanced Operating Procedures.59
With this range of potential mitigation strategies, it is appropriate to provide flexibility to the
responsible entities with respect to establishing timetables for completion.
The Corrective Action Plan must 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. This provision
ensures that there is coordination and communication among the functional entities. The
provision of information in proposed Requirement R7 Part 7.3 shall be subject to the legal and
regulatory obligations for the disclosure of confidential and/or sensitive information.
For the reasons described above, the proposed Reliability Standard is just and reasonable
and is designed to protect against instability, uncontrolled separation, or cascading failures of the
Bulk-Power System as a result of a Benchmark GMD Event through the performance of initial
and on-going GMD Vulnerability Assessments.

59

Mitigating measures and approaches, including geomagnetically-induced current reduction devices,
monitoring, and system reconfiguration, are discussed in Chapters 9 and 10 of the 2012 NERC Interim GMD Report
and Chapter 5 of the GMD Planning Guide (Dec. 2013).

32

F.

Implementation of Proposed Reliability Standard TPL-007-1

The implementation plan for proposed Reliability Standard TPL-007-1, included as
Exhibit B to this petition, provides a multi-phased approach to implementation over a five-year
period as follows:
•

Requirement R1, pertaining to establishing responsibilities among applicable
Planning Coordinators and Transmission Planners, shall become effective on the
first day of the first calendar quarter that is six months after regulatory
approval.60

•

Requirement R2, requiring the maintenance of System models and GIC System
models for performing the study or studies needed to complete GMD
Vulnerability Assessments, shall become effective on the first day of the first
calendar quarter that is 18 months after regulatory approval.

•

Requirement R5, which requires the responsible Planning Coordinators and
Transmission Planners to provide GIC flow information to applicable
Transmission Owners and Generator Owners for the transformer thermal impact
assessments specified in Requirement R6, shall become effective on the first day
of the first calendar quarter that is 24 months after regulatory approval.

•

Requirement R6, which requires applicable Transmission Owners and Generator
Owners to conduct thermal impact assessments and provide the results to the
responsible Planning Coordinators or Transmission Planners, shall become

60

“Regulatory approval” refers specifically to the date that the standard is approved by an applicable
governmental authority or as otherwise provided for in a jurisdiction where approval by an applicable governmental
authority is required for a standard to go into effect. The implementation plan also provides effective dates where
approval by an applicable governmental authority is not required for a standard to go into effect.

33

effective on the first day of the first calendar quarter that is 48 months after
regulatory approval.
•

Requirements R3, R4, and R7, which address establishing criteria for acceptable
System steady state voltage performance during the Benchmark GMD Event,
performing GMD Vulnerability Assessments, and developing Corrective Action
Plans to address identified vulnerabilities, respectively, shall become effective on
the first day of the first calendar quarter that is 60 months after regulatory
approval.

The proposed implementation plan provides for the proper sequencing of system and
equipment assessments performed by various applicable entities to build an overall assessment of
GMD vulnerability. In accordance with Order No. 779, the proposed implementation plan
provides an appropriate time period for applicable entities to obtain tools, models, and data
required for GMD Vulnerability Assessments.61 In many cases, applicable entities will be
developing GIC system models needed for proposed Requirement R2 and obtaining transformer
thermal models needed for proposed Requirement R6 for the first time. The proposed
implementation plan allows sufficient time for the necessary analysis and coordination. The
proposed implementation plan also provides the necessary time for the development of viable
Corrective Action Plans to address identified vulnerabilities. These Corrective Action Plans may
require entities to develop, perform, or validate new or modified studies, assessments, or
procedures to meet the requirements of the proposed standard. Further, some mitigation
measures may have significant budget, siting, or construction planning requirements. Therefore,

61

Order No. 779 at P 68 (“When developing the Second Stage GMD Reliability Standards implementation
schedule, NERC should consider the availability of validated tools, models, and data necessary to comply with the
Requirements.”).

34

the five-year phased implementation plan reflects an appropriate and realistic timeframe for
compliance with proposed Reliability Standard TPL-007-1.
G.

Commission Directives and Issues Addressed

As explained in Exhibit H, the proposed Reliability Standard addresses all of the
Commission’s directives in Order No. 779 with respect to Stage 2 of the GMD Reliability
Standards. In addition, the proposed Reliability Standard addresses a number of concerns and
issues identified for consideration by the Commission.
Provided below is an explanation of how the proposed Reliability Standard addresses
each Commission directive or how it addresses a concern or issue identified by the Commission
in Order No. 779.
1.

Benchmark GMD Event and Timing: Order No. 779, Paragraph 2

In Order No. 779, the Commission directed NERC to “submit, within 18 months of the
effective date of this Final Rule, one or more Reliability Standards that require owners and
operators of the Bulk-Power System to conduct initial and on-going vulnerability assessments of
the potential impact of benchmark GMD events on Bulk-Power System equipment and the BulkPower System as a whole.”62 The Commission also stated that the proposed Reliability Standard
must “identify ‘benchmark GMD events’ that specify what severity GMD events a responsible
entity must assess for potential impacts on the Bulk-Power System.”63
Proposed Reliability Standard TPL-007-1 requires initial and on-going vulnerability
assessments of the impact of a Benchmark GMD Event, as described herein. The severity of
GMD events is specified in the Benchmark GMD Event, which is set forth in Attachment 1. The

62
63

Order No. 779 at P 2.
Id.

35

benchmark provides a defined event for assessing system performance as required by the
proposed Reliability Standard. It also defines the geoelectric field values used to compute GIC
flows for a GMD Vulnerability Assessment.
Order No. 779 became effective on July 22, 2013. The instant petition is being submitted
within 18 months, in compliance with the Commission’s directive.64
2.

Costs and Benefits: Order No. 779, Paragraph 28

In Order No. 779, the Commission stated that it “expect[ed] NERC and industry [to]
consider the costs and benefits of particular mitigation measures as NERC develops the
technically-justified Second Stage GMD Reliability Standards.”65 While not a directive, NERC
solicited comments on mitigation costs from stakeholders during formal comment periods in
order to address the Commission’s concerns related to consideration of costs.
The standard drafting team chose a planning standard approach to meet the directives for
the second stage GMD Reliability Standard, which allows applicable entities flexibility to select
mitigation measures based on a variety of considerations, including costs. Like other existing
planning standards, proposed Reliability Standard TPL‐007‐1 does not prescribe specific
mitigation measures or strategies. When mitigation is necessary to meet the performance
requirements specified in the standard, applicable entities can evaluate options using criteria
which could include cost considerations.

64
65

Order No. 779 at P 18.
Order No. 779 at P 28.

36

3.

Identification of Facilities and Wide-Area Assessment: Order No. 779,
Paragraph 51

In Order No. 779, the Commission directed NERC to “‘identify facilities most at-risk
from severe geomagnetic disturbance’ and ‘conduct wide-area geomagnetic disturbance
vulnerability assessment’ as well as give special attention to those Bulk-Power System facilities
that provide service to critical and priority loads.”66
When fully implemented, proposed Reliability Standard TPL-007-1 will enable wide‐area
assessment of GMD impact. Through the standard development process, industry has provided
projections on the time required for obtaining validated tools, models, and data necessary for
conducting GMD Vulnerability Assessments. The five‐year phased implementation plan has
been tailored accordingly and reflects a realistic timeline for the performance of GMD
Vulnerability Assessments.
Corrective Action Plans required by proposed Reliability Standard TPL-007-1 provide
the means to address risk to all applicable facilities from a Benchmark GMD Event, not only
those determined to be most at‐risk in wide‐area assessments. Additionally, the proposed
Reliability Standard enhances NERC’s ability to further assess the reliability risks that GMDs
pose to the Bulk‐Power System through the reliability assessment functions described in Section
800 of the NERC Rules of Procedure. Once the proposed standard is fully implemented, NERC
and the Regional Entities will be better able to assess further the potential impacts of GMD
events on the Bulk‐Power System as a whole.

66

Order No. 779 at P 51 (internal citation omitted).

37

4.

Assessment Parameters: Order No. 779, Paragraph 67

In Order No. 779, the Commission stated that each responsible entity under the Second
Stage GMD Reliability Standards would “be required to assess its vulnerability to the benchmark
GMD events consistent with the five assessment parameters identified in the NOPR and adopted
in this Final Rule.”67 The proposed Reliability Standard requires applicable entities to perform
assessments that will identify the impacts from the Benchmark GMD Event on the
interconnected transmission system. The five assessment parameters are addressed as follows:
a)
Parameter No. 1: The Reliability Standards should contain
uniform evaluation criteria for owners and operators to follow when
conducting their assessments.
Evaluation criteria are uniformly established in proposed Requirement R4, Table 1 –
Steady State Planning Events, and Attachment 1 – Calculating Geoelectric Fields for the
Benchmark GMD Event. Proposed Requirement R4 specifies system conditions. Table 1
establishes uniform performance criteria. Attachment 1 describes the procedure for calculating
the Benchmark GMD Event for use in the GMD Vulnerability Assessment.
b)
Parameter No. 2: The assessments should, through studies and
simulations, evaluate the primary and secondary effects of GICs on
Bulk-Power System transformers, including the effects of GICs
originating from and passing to other regions.
Proposed Requirements R4 and R6 address assessments of the effects of GICs on
applicable transformers. Proposed Requirement R4 specifies that the responsible Planning
Coordinators or Transmission Planners (as determined in Requirement R1) must conduct GMD
Vulnerability Assessments that include steady state analysis to ensure transformer reactive losses

67

Order No. 779 at P 67 (internal citation omitted).

38

from the Benchmark GMD Event do not produce voltage collapse, Cascading, and uncontrolled
islanding. Proposed Requirement R6 specifies that applicable Transmission Owners and
Generator Owners must conduct thermal impact assessments of applicable power transformers.
Proposed Requirement R4 Part R4.3 provides for information-sharing so that the effects of GICs
in other planning areas are factored into GMD Vulnerability Assessments. Specifically,
proposed Requirement R4 Part 4.3 specifies that GMD Vulnerability Assessments must be
provided to the responsible entity's Reliability Coordinator, adjacent Planning Coordinators,
adjacent Transmission Planners, and to any functional entity that submits a written request and
has a reliability related need.
c)
Parameter No. 3: The assessments should evaluate the effects
of GICs on other Bulk-Power System equipment, system operations,
and system stability, including the anticipated loss of critical or
vulnerable devices or elements resulting from GIC-related issues.
In addition to assessing heating and reactive power effects in transformers, proposed
Requirements R4 and Table 1 – Steady State Planning Events address assessments of the effects
of GICs on other Bulk‐Power System equipment, system operations, and system stability,
including the loss of devices due to GIC impacts. The study or studies conducted by the
applicable Planning Coordinators and Transmission Planners in complying with Requirement R4
must evaluate the performance of the System during a Benchmark GMD Event to prevent
voltage collapse, Cascading, and uncontrolled islanding. Devices that Planning Coordinators and
Transmission Planners anticipate may be susceptible to harmonic impacts as a result of GIC are
to be removed from the System in the analysis, since these devices may affect System
performance. Thus, the GMD Vulnerability Assessment includes the effects caused by GIC on
the reliable operation of the Bulk-Power System.
39

d)
Parameter No. 4: In conjunction with assessments by owners
and operators of their own Bulk-Power System components, widearea or Regional assessments of GIC impacts should be performed. A
severe GMD event can cause simultaneous stresses at multiple
locations on the Bulk-Power System, potentially resulting in a
multiple-outage event. In predicting GIC flows, it is necessary to take
into consideration the network topology as an integrated whole (i.e.,
on a wide-area basis).
Proposed Reliability Standard TPL-007-1 accounts for wide‐area impacts by requiring
information exchange and involving appropriate entities. Proposed Requirement R4 and
Requirement R7 specify that GMD Vulnerability Assessments and Corrective Action Plans must
be provided to Reliability Coordinators, adjacent Planning Coordinators and Transmission
Planners, and the functional entities specifically referenced in the plans. Reliability Coordinators
work together to maintain real‐time reliable operations in the wide area. The information in
GMD Vulnerability Assessments and Corrective Action Plans from entities in the Reliability
Coordinator area will support this function. Planning Coordinators integrate plans within their
areas and coordinate plans with adjacent Planning Coordinators as described in the NERC
Functional Model.68
e)
Parameter No. 5: The assessments should be periodically
updated, taking into account new facilities, modifications to existing
facilities, and new information, including new research on GMDs, to
determine whether there are resulting changes in GMD impacts that
require modifications to Bulk-Power System mitigation schemes.
Proposed Reliability Standard TPL-007-1 requires GMD Vulnerability Assessments to be
periodically updated, not to exceed every 60 calendar months from the preceding GMD

68

NERC, Reliability Functional Model Technical Document v. 5 (Dec. 2009) at 10-11, available at
http://www.nerc.com/pa/Stand/Functional%20Model%20Archive%201/FM_Technical_Document_V5_2009Dec1.p
df.

40

Vulnerability Assessment. The periodicity was established with consideration to the highimpact, low-frequency nature of the Benchmark GMD Event.
5.

Improvements in Scientific Understanding of GMDs: Order No. 779,
Paragraph 68

In Order No. 779, the Commission stated that NERC should consider “developing
Reliability Standards that can incorporate improvements in the scientific understanding of
GMDs.”69 NERC considered and addressed the Commission’s concerns.
The Requirements in proposed Reliability Standard TPL-007-1 are performance‐based,
which allows applicable entities to use state of the art tools and methods to accomplish the
specified reliability objectives. The standard does not contain prescriptive requirements for
applicable entities to use specific tools, models, or procedures which would limit the
applicability of improvements in scientific understanding. Furthermore, the use of modern
magnetometer data and statistical methods in determining the Benchmark GMD Event supports
reevaluation as additional magnetometer data are collected during future solar cycles.

6.

Plans to Protect Against Instability, Uncontrolled Separation, or
Cascading Failures of the Bulk-Power System: Order No. 779,
Paragraph 79

In Order No. 779, the Commission directed NERC to submit for approval one or more
Reliability Standards that, in the event potential impacts from a benchmark GMD event are
identified:
[R]equire owners and operators of the Bulk-Power System to
develop and implement a plan to protect against instability,
uncontrolled separation, or cascading failures of the Bulk-Power
69

Order No. 779 at P 68.

41

System, caused by damage to critical or vulnerable Bulk-Power
System equipment, or otherwise, as a result of a benchmark GMD
event.70
This directive is addressed by proposed Requirement R7 of proposed Reliability Standard
TPL-007-1. An entity must develop a Corrective Action Plan in the event its System fails to
meet specified performance criteria. Proposed Requirement 7 Part 7.1 lists acceptable actions,
which are not limited to considering Operating Procedures or enhanced training.

7.
Performance of Vulnerability Assessments and Developing Plans to
Mitigate Identified Vulnerabilities: Order No. 779, Paragraph 82
In Order No. 779, the Commission stated, “As with the First Stage GMD Reliability
Standards, the responsible entities should perform vulnerability assessments of their own systems
and develop the plans for mitigating any identified vulnerabilities.”71 As discussed above, the
proposed standard requires applicable entities to conduct assessments on their systems and
develop plans to mitigate identified vulnerabilities. In proposed Requirement R1, applicable
Planning Coordinators and Transmission Planners identify responsibilities for maintaining
models and performing studies needed for GMD Vulnerability Assessments, as specified in
Requirement R4. In proposed Requirement R6, applicable Transmission Owners and Generator
Owners are required to conduct thermal impact assessments of applicable BES power
transformers and, if necessary, specify mitigating actions. Proposed Requirement R7 requires
the responsible Planning Coordinator or Transmission Planner (as determined in Requirement
R1) to develop a Corrective Action Plan in the event that it concludes, through the GMD
Vulnerability Assessment, that its system does not meet performance requirements.

70
71

Order No. 779 at P 79.
Order No. 779 at P 82.

42

8.

Strict Liability: Order No. 779, Paragraph 84

The Commission noted in Order No. 779 that the second stage Reliability Standards
“should not impose ‘strict liability’ on responsible entities for failure to ensure the reliable
operation of the Bulk-Power System in the face of a GMD event of unforeseen severity, as some
commenters fear.”72 In accordance with Order No. 779, proposed Reliability Standard TPL-0071 establishes requirements for evaluating and mitigating the impacts of a Benchmark GMD
Event on the reliable operation of the Bulk-Power System, but does not impose strict liability on
responsible entities for failure to ensure reliable operation during a GMD event of unforeseen
severity. Instead, the proposed Reliability Standard is designed to ensure the reliable operation
of the Bulk-Power System in response to the identified Benchmark GMD Event. The
identification of a robust and technically-justified Benchmark GMD Event in the Reliability
Standard addresses the concern that responsible entities might otherwise be required to prevent
instability, uncontrolled separation, or cascading failures of the Bulk-Power System when
confronted with GMD events of unforeseen severity.

9.

Automatic Blocking Measures: Order No. 779, Paragraph 85

In Order No. 779, the Commission stated that it would not require the use of automatic
blocking measures in the second stage GMD Reliability Standards. The Commission stated,
“given that some responsible entities have or may choose automatic blocking measures, the

72

Order No. 779 at P 84.

43

NERC standards development process should consider how to verify that selected blocking
measures are effective and consistent with the reliable operation of the Bulk-Power System.”73
The GMD Vulnerability Assessment process considers all mitigation measures in
modeling, assessment, and mitigation requirements. Proposed Requirement R2 specifies that the
responsible entity (i.e. the Planning Coordinator or Transmission Planner(s), as determined in
Requirement R1) shall maintain system models for performing GMD Vulnerability Assessments,
which will include automatic blocking measures that are part of the system as described in the
technical guidance.74 The responsible entity must perform studies based on these models, as
required in proposed Requirement R4, to verify effectiveness and the reliable operation of the
Bulk-Power System. When an applicable Transmission Owner or Generator Owner (R6) or
responsible Planning Coordinator or Transmission Planner (R7) identifies a need for mitigation
actions such as blocking measures, proposed Requirements R6 and R7 specify that information
must be shared with planning entities. A planning entity is in the best position to identify
whether selected mitigation actions are effective to address the GMD impacts identified in the
GMD Vulnerability Assessment and are consistent with the reliable operation of its System. In
this way, the standards development process has addressed evaluation of automatic blocking
measure effectiveness on the reliable operation of the Bulk-Power System.
\
10.

Reliability Goals: Order No. 779, Paragraph 86

In Order No. 779, the Commission stated that “the NERC standards development process
should consider how the reliability goals of the proposed Reliability Standards can be achieved

73
74

Order No. 779 at P 85.
See generally GIC Application Guide.

44

by a combination of automatic measures including, for example, some combination of blocking,
improved “withstand” capability, instituting specification requirements for new equipment,
inventory management, and isolating certain equipment that is not cost effective to retrofit.”75
This suggestion is addressed by proposed Requirement R7 of proposed Reliability
Standard TPL-007-1. When a responsible Planning Coordinator or Transmission Planner
concludes through the GMD Vulnerability Assessment that its System does not meet
performance requirements, it is required to develop a Corrective Action Plan. The plan must list
deficiencies and the associated actions needed to achieve required performance. Proposed
Requirement R7 provides examples of such actions, including installation or modification of
equipment, use of Operating Procedures, and other actions specified in the Requirement.

11.

Implementation Plan: Order No. 779, Paragraph 91

In Order No. 779, the Commission specified a number of considerations for NERC in
developing an implementation plan for the second stage GMD Reliability Standard. The
Commission stated:
As stated in the NOPR, in a proposed implementation plan, we
expect that NERC will consider a multi-phased approach that
requires owners and operators of the Bulk-Power System to
prioritize implementation so that components considered vital to the
reliable operation of the Bulk-Power System are protected first. We
also expect, as discussed above, that the implementation plan will
take into account the availability of validated tools, models, and data
that are necessary for responsible entities to perform the required
GMD vulnerability assessments.76

75
76

Order No. 779 at P 86.
Order No. 779 at P 91.

45

NERC’s implementation for proposed Reliability Standard TPL-007-1 is included as
Exhibit B to this petition. As described above, the proposed implementation plan provides a
multi-phased approach to implementation over a five-year period.
Phased implementation will provide the necessary time for applicable entities to develop
the required models and for proper sequencing of system and equipment assessments performed
by various applicable entities to build an overall assessment of GMD vulnerability. The
proposed implementation plan takes into account the availability of validated tools, models, and
data that are necessary to perform GMD Vulnerability Assessments.
Additionally, phased implementation will provide the necessary time for the development
of viable Corrective Action Plans, which may require entities to develop, perform, or validate
new or modified studies, assessments, and procedures to meet the TPL-007-1 requirements.
Some mitigation measures may have significant budgeting, siting, or construction planning
requirements.
GMD Vulnerability Assessment results are necessary to identify components that are
vital to reliable operation during a benchmark GMD event. Therefore, a phased implementation
approach will provide an appropriate time period for applicable entities to develop Corrective
Action Plans that address identified impacts in a prioritized manner.

H.

Enforceability of Proposed Reliability Standard TPL-007-1

The proposed Reliability Standard includes Violation Risk Factors (“VRFs”) and
Violation Severity Levels (“VSLs”). The VSLs provide guidance on the way that NERC will
enforce the Requirements of the proposed Reliability Standard. The VRFs are one of several
elements used to determine an appropriate sanction when the associated Requirement is violated.
The VRFs assess the impact to reliability of violating a specific Requirement. The VRFs and
46

VSLs for the proposed Reliability Standards comport with NERC and Commission guidelines
related to their assignment. For a detailed review of the VRFs, the VSLs, and the analysis of
how the VRFs and VSLs were determined using these guidelines, please see Exhibit G.
The proposed Reliability Standard also include Measures that support each Requirement
by clearly identifying what is required and how the Requirement will be enforced. These
Measures help ensure that the Requirements will be enforced in a clear, consistent, and nonpreferential manner and without prejudice to any party.77

77

Order No. 672 at P 327 (“There should be a clear criterion or measure of whether an entity is in compliance
with a proposed Reliability Standard. It should contain or be accompanied by an objective measure of compliance so
that it can be enforced and so that enforcement can be applied in a consistent and non-preferential manner.”).

47

V.

CONCLUSION

For the reasons set forth above, NERC respectfully requests that the Commission
approve:
•

the proposed Definition;

•

the proposed Reliability Standard in Exhibit A;

•

the other associated elements in the Reliability Standard in Exhibit A, including the
VRFs and VSLs (Exhibits A and G); and

•

the implementation plan, included in Exhibit B.

Respectfully submitted,
/s/ Lauren A. Perotti
Charles A. Berardesco
Senior Vice President and General Counsel
Holly A. Hawkins
Associate General Counsel
Lauren A. Perotti
Counsel
North American Electric Reliability Corporation
1325 G Street, N.W., Suite 600
Washington, D.C. 20005
(202) 400-3000
(202) 644-8099 – facsimile
[email protected]
[email protected]
[email protected]

Counsel for the North American Electric
Reliability Corporation
Date: January 21, 2014

48