Jerry RustChair - Underfrequency Load Shedding

Criterion Team

WECC Regional Criterion PRC-006-WECC-CRT-1 (Project WECC-0065) Underfrequency Load

Shedding Criterion September 9, 2011

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• Purpose of UFLS• Background• Current Situation• Purpose of PRC-006-WECC-CRT-1• Proposed Criteria• Implementation• Next Steps

PRC-006-WECC-CRT-1

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Last automatic protection scheme to arrest the frequency decline after a disturbance

Load Shedding Occurs; Frequency decline was arrested; and, Recovery was observed.

PRC-006-WECC-CRT-1

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July 2 & 3, 1996 and August 10, 1996 Western Interconnection wide disturbances

oWECC Disturbance Report Complete review of the Underfrequency load

shedding programs Coordination with generator off-nominal frequency

protection requirements Coordination of automatic and manual load

restoration Coordination between and within sub-regions of the

Western Interconnection

Background - PRC-006-WECC-CRT-1

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November 8, 1996 ad hoc Underfrequency Issues Work Group (UIWG) formed

o Determine if a uniform UFLS program can be specified for all of WECC

o If yes, recommend a uniform off-nominal frequency program

o Recommend a policy regarding the automatic restoration of load

o Recommend a policy regarding intentional tripping of tie lines and generators due to underfrequency

Background - PRC-006-WECC-CRT-1

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The Western Electricity Coordinating Council Operating and Planning Committees have established a joint goal to review the effectiveness of the design and implementation of the WECC Coordinated Off-Nominal Frequency Load Shedding and Restoration Program

WECC 2009 Goals for UFLS

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•WECC UFLS – Test EffectivenessoReview of frequency set pointsoReview of Generator tripping set pointsoReview of Automatic Restoration

•Address the NERC registered entities – Correct Entities and inventory•Consistent with PRC standards – Gen Standards•Address Variable Generation•Full and detailed documentationoSouthern Island Load Tripping PlanoNWPP UFLS PlanoOthers

WECC 2009 Goals for UFLS

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•Inventory•Topology (variable generation)•SimulateoVarious CasesoSolve for Worst Case Contingency

•Recommended Changes if Necessary

WECC 2009 Approach for UFLS

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•Findings October 2009•Changes if NecessaryoRecommendations October 2009

•Full and detailed documented Plan – First quarter 2010 (if not sooner)

WECC 2009 Time-Frame for UFLS

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•Over 200 simulations utilizing the existing inventory of relay and associated armed load verifies the following:

Load Shedding Occurs; Frequency decline was arrested; and, Recovery was observed.

•The WECC plans still performed under simulation as originally designed.

WECC 2009 Findings for UFLS

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NERC PRC-006-0 is categorized as a fill-in-the-blank standard.  The WECC Board of Directors has instructed WECC to utilize the Process for Developing and Approving WECC Standards whenever drafting criteria to meet NERC fill-in-the-blank requirements and to categorize the resultant work product as a criterion under the WECC Document Categorization procedures. 

Purpose - PRC-006-WECC-CRT-1

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• No Changes to Existing Plan• Consolidate the Existing Plan• Define how to implement Existing Plan• Develop timelines to NERC requirements• Define responsible entities

Goals - PRC-006-WECC-CRT-1

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• WECC Coordinated Plan - consolidated 12 pages, approved 1st quarter 2011 by the OC and PCC, approved by WECC Board of Directors 2nd quarter 2011

• WECC Coordinated Plan recognizes sub-plans, such as NWPP and SILT

• No changes to the existing plan

Consolidation - PRC-006-WECC-CRT-1

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• WECC Coordinated Plan first level of underfrequency load shedding occurs at 59.5 Hz (SILT) next at 59.3 Hz (NWPP) and then 59.1 Hz (the remaining WECC)

• WECC Coordinated Plan may be changed in accordance with WECC process

• WECC Coordinated Plan currently meets NERC Reliability Standards

Consolidation - PRC-006-WECC-CRT-1

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• The WECC JGC established the requirement for a UFLS “Review Group”

• A joint regional group comprised of WECC Balancing Authorities, Planning Coordinators, Transmission Operators, and Transmission Planners created by the WECC Joint Guidance Committee to review and maintain an accurate underfrequency load shedding database and simulation models reflecting the WECC Off-Nominal Frequency Load Shedding Plan.

• WECC Review Group to receive the required information and assure WECC Coordinated Plan performs under simulation as designed

PRC-006-WECC-CRT-1

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• Underfrequency load shedding entities (UFLS Entities) shall mean all entities that are responsible for the ownership, operation, or control of UFLS equipment as required by the Coordinated Plan. Such entities may include one or more of the following:

Transmission Owner Distribution Provider

PRC-006-WECC-CRT-1

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• BA peak load is armed in accordance with WECC Coordinated Plan

• BA to allocate its historical peak load to TOPs• TOPs must identify which sub-area Coordinated Plan they

are following (e.g. NWPP, SILT, or WECC)• TOPs or its agent to coordinate with UFLS Entities to

assure underfrequency relays are in place and armed in accordance with the WECC Coordinated Plan

PRC-006-WECC-CRT-1

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• The criterion allows for flexibility of various combinations of the UFLS Entities to meet the requirements and fulfill the WECC Coordinated Plan

PRC-006-WECC-CRT-1

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Each Transmission Operator or its agent shall produce documentation showing how it coordinated implementation of each sub-area Coordinated Plan of the Coordinated Plan with its UFLS Entities. Documentation may include, but is not limited to, evidence of how the adopted sub-area Coordinated Plan of the Coordinated Plan is implemented among the TOP and the UFLS Entities.

PRC-006-WECC-CRT-1

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Each UFLS Entity or its agent shall coordinate and provide documentation of its responsibilities in meeting the Coordinated Plan to the Review Group. Documentation shall include:

A listing of its responsibilities as required under the Coordinated Plan.

A designation of the agent responsible for all data submission to demonstrate compliance with the Coordinated Plan

PRC-006-WECC-CRT-1

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• Each UFLS Entity or its agent shall compile their respective Coordinated Plan data and dynamics file in the WECC-defined format, as listed in the Coordinated Plan – Data Submittals Requirements (Attachment B of this criterion), for its entire load and annually, by June 1, submit Attachment B to the Review Group and to the UFLS Entity’s respective Transmission Operator.

PRC-006-WECC-CRT-1

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• Each Generator Owner shall annually compile and submit to the Review Group, no later than June 1, their respective Coordinated Plan data and dynamics file for its generation, in the format defined in Attachment B of this criterion.

PRC-006-WECC-CRT-1

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• The Review Group to coordinate and perform all post-event analyses associated with the Coordinated Plan.

PRC-006-WECC-CRT-1

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• It is anticipated that this document will be ready for WECC standing committee and Board of Director approval in time to be effective on January 1, 2012. If the necessary approvals are received in time for an effective date of January 1, 2012, the following dates will be enforced:

• Balancing Authority shall meet R5 for the first time on June 1, 2012

• UFLS Entities shall meet R9 for the first time on June 1, 2012.

Time-Frame PRC-006-WECC-CRT-1

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• Generator Owners will meet R12 for the first time on June 1, 2012.

• The Review Group will complete the first annual review of the Coordinated Plan by November 1, 2012.

• If the necessary approvals are not obtained in time for this criterion to become effective on January 1, 2012, then the dates above will be incremented to 2013.

Time-Frame PRC-006-WECC-CRT-1

Questions?

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• Level 1 32 pto Level 2 28 pt

Level 3 24 pt

PRC-006-WECC-CRT-1

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• Level 1 32 pto Level 2 28 pt

Level 3 24 pt

PRC-006-WECC-CRT-1