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WECC-0100 TPL-001-WECC-CRT-3 System PerformanceDrafting Team (DT)

Response to Comments / Posting 3July 24 through August 24, 2015

Posting 3

The WECC-0100 TPL-001-WECC-CRT-3, System Performance Drafting Team (DT) thanks everyone who submitted comments on the proposed document.

Posting

This document was last posted for a 30-day public comment period from July 24 through August 24, 2015.

WECC distributed the notice for the posting on July 23, 2015. The DT asked stakeholders to provide feedback on the proposed document through a standardized electronic template. WECC received comments from 13 respondents representing six of the eight Industry Segments, as shown in the WECC Standards Voting Sector table that follows.

Location of Comments

All comments received on the document can currently be viewed in their original format on the project page under the “Submit and Review Comments” accordion.

Changes in Response to Comment

After consideration of comments received, the DT made the following changes:

Purpose Statement

Purpose: To facilitate coordinated near-term and long-term transmission planning for the Western Interconnection, and to facilitate the exchange of the associated plan-ning information for normal and abnormal conditions.

This document applies to all transmission planning studies conducted within the Interconnection of the Western Electricity Coordinating Council (WECC).

Facilities Section

4.1. Facilities:

4.2.1. This document applies to Bulk Electric System (BES) substations buses.

1

Comment Report Form for WECC-0100 2

4.2.2. Each of the following elements is specifically excluded from this Crite-rion:

4.2.2.1. Non-BES buses.

4.2.2.2. Line side series capacitor buses

4.2.2.3. Line side series reactor buses

4.2.2.4. Dedicated shunt capacitor buses

4.2.2.5. Dedicated shunt reactor buses

4.2.2.6. Metering, fictitious, or other points of interconnection modeled solely for measuring electrical quantities; and,

4.2.2.7. Other buses specifically excluded by each Planning Coordi-nator or Transmission Planner internal to their system.

Requirements and Measures

Requirement WR1.1 now reads (emphasis added):

1.1. Steady-state voltages at all applicable Bulk-Electric System (BES) buses shall stay within each of the following limits:

1.1.1 95 percent to 105 percent of nominal for P01 event (system normal pre-contingency powerflow);

1.1.2 90 percent to 110 percent of nominal for P1-P72 events (post-contingency powerflow).

Requirement WR1.5 and 1.6 Rationale Box has been redrafted for clarity.

Requirement WR1.1.6 now includes the word “all” as a definitive (emphasis added):

1.6 All oscillations that do not show positive damping within a 30-second time frame shall be deemed unacceptable.

Requirement WR2 typo has been corrected from R2 to WR2.

1 P0 through P7 refers to the categories of contingencies identified in Table 1 of NERC Standard TPL-001-4, Transmission System Planning Performance Requirements. 2 Previously cited


Requirement WR5 was redrafted for clarity (emphasis added):

WR5. Each Transmission Planner and Planning Coordinator shall use the following mini-mum criteria when identifying voltage stability:

Effective Date

The Effective Date has been redrafted as follows:

“The Effective Date is the later of January 1, 2016 or the Effective Date of TPL-001-4, Transmission Plan-ning Performance System Requirements, Requirements R2-R6 and R8.”

Implementation Plan

An Implementation Plan was included in the preamble of Posting 3.

Minority Position

The DT opted not to accept Modesto’s suggestion to identify all entities containing specific tariff requirements. Including a static list of each entity would require a full examination of all entities within WECC. Further, it would require re-opening this document each time an entity changed.

Action Plan

TEXT

Pending items from the Posting 1 include:

Evaluation of whether to adopt, modify, or delete WR1.4 Table W-1. To do so is within the scope of the Standards Authorization Request but is not mandated. (Xcel)

Evaluation of whether to retain the PRC-024-1 curve in the document. (Idaho Power)

White paper

o The drafting team committed to pursuing a white paper to address simulations needed to justify and refine the proposed criteria. Drafting efforts on the paper have begun in consultation with the Modeling Validation Work Group. (BPA, Xcel)

Contacts and Appeals

If you feel your comment has been omitted or overlooked, please contact the Manager, WECC Standards Processes, W. Shannon Black, at [email protected]. In addition, there is a WECC Reliability Standards Appeals Process.


The WECC Standards Voting Sectors are:

1 — Transmission Sector2 — Generation Sector 3 — Marketers and Brokers Sector4 — Distribution Sector 5 — System Coordination Sector6 — End Use Representative Sector7 — State and Provincial Representatives Sector8 — Other Non-Registered WECC Members and Participating Stakeholders Sector

Commenter Organization WECC Standards Voting Sectors

1 2 3 4 5 6 7 8

1 Spencer Tacke Modesto Irrigation District X X X X X

2 James Hirning Western Area Power Administration

X X X X X

3 Gordon Comegys G2 Power Consulting X3

4 Ryan Hubbard Tri-State Generation and Transmission, Inc.

X X X X X

5 Eleanor Ewry Puget Sound Energy X X X X X

6 Venkataramakrishnan Vinnakota

BC Hydro X X X X

7 Hamody Hindi MVWGX4

8 Gary Trent Tucson Electric X X X

9 Jeff Watkins NV EnergyX5

3 Not registered in the Ballot Body4 Not registered in the Ballot Body.


Commenter Organization WECC Standards Voting Sectors

1 2 3 4 5 6 7 8

10 Jeremy Brownrigg Platt River X X X X X

11 Joshua Anderson Salt River Project X x X X X

12 Stephanie Lu Seattle City Light X X X X X

13 Anupama Pandey Pacific Gas and Electric X X

14 Marcus Lotto DECIDE WHETHER TO ADDRESS LATE COMMENTS.

Southern California Edison

5 Not registered in the Ballot Body.


Index to Questions, Comments, and Responses

Question

1. The drafting team welcomes comments on all aspects of the document.


1. The drafting team invites comments on all aspects of the document.

Summary Consideration: See summary in the preamble of this document.

Commenter Yes No Comment

Modesto 1. Recommendation that the Rationale document, which includes the waveform diagrams, should be part of the TPL-001-WECC-CRT-3 Criterion document in total.

2. Under the Rational for Requirement WR1.2, please indi-cate who the "certain entities are" that are bound by state tariffs that establish the eight percent voltage de-viation. Also, in regards to the statement that the eight percent target is established based on sound engineer-ing judgment, making an engineering judgment still re-quires a reference point. Where is that reference and supporting data for the eight percent value?

3. Recommend revising Section 1.3's phrase "within 10 seconds" to "within 20 seconds". This recommendation is based on observation of demonstrated actual system FIDVR event data, indicating that typical voltage recov-ery times to within 80% of the pre-event voltage value, are larger than 10 seconds, and are typically 15 to 20 seconds.

4. Recommend revising Section 1.6 to add the word "All" before the word "Oscillations".

Issue 1: Move Rationale to the Main Body Pending Issue 2: Under the Rational for Requirement WR1.2, designate all entitiesThe DT opted not to accept Modesto’s suggestion. Including a static list of each entity would require a full examination of all entities within WECC. Further, it would require re-opening this document each time an entity changed. Issue 3: Supporting data for 8% reference pointPending Issue 4: Revise Section 1.3's phrase "within 10 seconds" to "within 20 seconds"Pending Issue 5: Section 1.6, add “All” before “Oscillations”

The word was added.

Western Area Power Administration

1. WR1.1.2. The upper limit has changed since posting 2.

In order for this to move forward it needs to return to 110 per-




cent of nominal.

ANSI/NEMA C84.1 shows the maximum system and utilization voltages as 1.05. The statement on system voltage in C84.1 Sec-tion 5.1.1 does not preclude voltages outside this range, but state "The occurrence of service voltages outside these limits should be infrequent." Additionally, in the Scope of the docu-ment, Section 1.1, the standard states "In defining maximum system voltage, voltage transients and temporary over voltages caused by system conditions such as faults, load rejection, and the like are excluded." And, Section 2.2.3 states that the maxi-mum system voltage is "the highest system voltage for which equipment and other components are designed for satisfactory continuous operation without de-rating of any kind." This does not preclude their use at higher voltages with de-rating. Equip-ment manufacturers tell us that they state their high-end volt-age level for operation is deemed as 1.05 p.u., but the equip-ment will not malfunction at voltages outside this. 1.10 p.u. has been the threshold used since the 1970's as the high-bookend voltage to hold to for any studied contingency. Therefore, this limit is historically proven, and to propose a change here would unravel years of planning studies.

2. WR1.3, WR1.4, and WR1.5 seem like adequate efforts to measure system performance, but in practice, at times, they may be unclear whether they are measuring system perfor-mance or system modeling. For example, suppose there is one pumping load bus in a neighboring system that slightly dips be-low these criteria in a transient study after a contingency. There is not a specific relay modeled to trip the load, although the planner believes some sort of protection could trip it. Even if the load hangs one, it does not affect other bus voltages in the system. Has the performance criterion been violated?

Requiring a strict adherence to these stated values may be diffi-cult for some contingencies, especially P5 through P7 events, which allow for Non-Consequential load loss.

Additionally, entities are currently completing TPL studies ac-cording to the TPL-001-4 to be compliant by January 1, 2016.




Likely, entities have already adopted a criterion of their own or are using the prior "finger" diagram.

These criteria could be revised to allow for more latitude if they are violated. For example, perhaps these criteria could be la-beled as a "proxy" for distribution level relay operation. In this manner, the planner must assume loads on these buses tripped, and the planner must also show the disturbance is con-tained (even if the load does not trip).

3. In WR1.6, there should be some additional language to clarify what will probably be confusion about whether the "30 second time frame" is simply any 30 second window, or whether it is specifically the 30 second window that begins after fault clear-ing (or after a no fault P2.1 event) and ends exactly 30 seconds later.

4. WR2 and WR3 allow any entity to have different require-ments than those given in WR1. The effectively makes WR1 NOT a requirement.

Furthermore, allowing entities to define more stringent or less stringent voltage limits on certain parts of their system for the steady-state simulation will be nearly impossible to implement unless WECC [begins] sic asking for bus voltage limit criteria to be input into base cases (similar to the MVA ratings). In the transient simulations, there may not be any good way for enti-ties to monitor varying requirements that have been defined on each bus in other systems.

Additionally, there is no clear mechanism to enforce whether entities are abiding by less restrictive or more restrictive limits that have been defined. What happens if an entity defines a less restrictive limit, but then later desires to go back to the limit stated in WR1?

WR2 and WR3, therefore, do not provide value to this docu-ment if it is to remain a criterion.

5. In WR4, the first bullet should be clarified to say "results in




steady-state facility loading." The second bullet may be too stringent in identifying potential cascading as "any" applicable BES bus voltage outside the stated transient limit. As explained above, strict adherence to these stated values may be difficult for some contingencies, especially P5 though P7 events, which allow for some Non-Consequential load loss.

6. Western would prefer that this re-write be categorized as a Guideline vs. Criteria document. WR1 includes what can be in-terpreted as criteria - the voltage levels for N-0 and N-1; how-ever, WR2 and Wr3 allow folks to have differing "criteria". So it seems, this basically undoes WR1 and the document no longer reads as a Criteria. Categorizing as a Guideline can be accom-plished by doing away with WR1 through WR4 as proposed and re-write WR6 to say that each TP and PC shall provide its TPL-001-4 R5 voltage criteria upon request. Put WR1 and WR4 as a Guideline. Then WR5 and WR6 become WR1 and WR2 respec-tively.

7. The introduction says, "This document applies to all transmis-sion planning studies conducted at the Western Interconnec-tion level." WR5 requires the Transmission Planner and Plan-ning Coordinator to identify voltage stability. Does this mean that the Criterion requires WECC entities to perform a post-transient voltage stability analysis for annual TPL assessments, even though NERC TPL-001-4 only requires steady-state, tran-sient, and short-circuit analysis? Perhaps more clarity could be added here to answer that question.

8. As currently written, the proposed criterion doesn't state anything about allowable effects on your neighbors, which is what some folks seemed concerned about. The current TPL Cri-terion Table speaks specifically about allowable effects on your neighbor. This issue needs to be addressed.

9. There seem to be some minor formatting errors, and the words "Transmission Planner" and "Planning Coordinator" should be spelled out throughout the document.

Issue 1: WR1.1.2. Return upper limit to 110% (as in Posting 2)




The DT accepted the suggestion. WR1.1 now reads:

1.1. Steady-state voltages at all applicable Bulk-Electric System (BES) buses shall stay within each of the following limits:

1.1.1 95 percent to 105 percent of nominal for P06 event (system normal pre-con-tingency powerflow);

1.1.2 90 percent to 110 percent of nominal for P1-P77 events (post-contingency powerflow).

Issue 2: WR1.3, WR1.4, and WR1.5 revise to allow more latitude / proxy for distribution PENDINGIssue 3: WR1.6, clarify “30 second time frame" – a general or specific windowPENDINGIssue 4: WR2 and WR3 cancel out WR1 – WR1 is voidThe DT does not concur that WR2 and WR3 cancel out WR1. To clarify the interaction between the three requirements, the following information has been added to the Rationale block. WR1 is designed to state the base criteria at which the study must be conducted – unless otherwise speci-fied. WR1 is the default whereas WR2 and WR3 allow for an exception to the default. Neither WR2 nor WR3 changes the WR1 default; rather, both WRs create an allowable deviation form the default. WR2 allows for a more stringent approach without changing the WR1 default. A more stringent approach may be used in accordance with WR2 so long as all the affected parties agree. Similarly, WR3 al-lows deviation from the default with the additional protection that when used, other Transmission Plan-ners and Planning Coordinfators are allowed to use the same criteria on that part of the system for the same category of planning events (e.g., P1 and P2). Issue 5: Impossible to implement without WECC interventionPending Issue 6: What happens if an entity defines a less restrictive limit, but then later desires to go back to the limit stated in WR1?Pending Issue 7: WR4, bullet 1 clarify to say “results in steady-state facility loading."Pending Issue 8: Guideline or CriteriaThe DT agreed to request that the Planning Coordinating Committee (PCC) place an approval item on its October 2015 agenda to seek industry consensus on which type of document this project should repre-sent: a WECC Criterion or a WECC Guideline. The DT consensus remains that the document should be

6 P0 through P7 refers to the categories of contingencies identified in Table 1 of NERC Standard TPL-001-4, Transmission System Planning Performance Requirements. 7 Previously cited




WECC Criterion. The DT is seeking final disposition on the issue and is in hopes of solidifying consensus by the voting con-stituency. Although an earlier PCC straw poll (July 2013) had concluded that a WECC Criterion best suited the project, subsequent understanding of document categorization and the current trajectory of the project may have swayed that advisory position.Issue 9: WR5 / Does this mean that the CRT requires entities perform a post-transient voltage sta-bility analysis for annual TPL assessments, even though NERC TPL-001-4 only requires steady-state, tran-sient, and short-circuit analysis?To clarify the language, the DT redrafted WR5 as follows:

WR5. Each Transmission Planner and Planning Coordinator shall use the following minimum criteria when identifying voltage stability: (emphasis added)

Issue 10: Silent on allowable effects on your neighborsThe DT disagrees with WAPA’s interpretation of the interaction between WR1, WR2, and WR3. Please re-fer to the language added to the WR1 Rationale block. WR2 protects ones neighbors in that a more strin-gent criteria cannot be used without communication and collaboration between the affected parties. WR3 protects ones neighbors in that one’s neighbors are allowed to use the less stringent criteria to prevent any adverse impact. Issue 11: Formatting

The document will be screened for technical writing at or near the termination of the drafting process.

G2 Power The rationale for WR1.2 states "only automatic post-contingency actions including capacity or reactor switching are considered when calculating voltage deviation". Please provide a maximum time for automatic actions. For example, automatic voltage controls at some generators slowly restore high side voltage at the GSU to a voltage schedule 10-20 minutes after the initial voltage deviation. Should this action be included in the calculation?

Issue 1: Rationale WR1.2 / Provide maximum time for automatic actions

Clarification of the WR was added in the Rationale box.The following sentence has been elaborated. “By default, only automatic post-contingency actions occurring in the studied timeframe, including capacitor or reactor switching, are considered when calculating voltage deviation.” (emphasis added)

This rationale recognizes that differing time windows may be studied at different times.

Tri-State Here are the comments gathered from people at Tri-State.




There are three diagrams, the first showing FIDVR crite-ria, the second showing normal voltage recovery crite-ria, but I can't tell what the third one is or why it is there.

The second diagram should have two time spans shown, one for length of voltage dip less than 80% of pre-con-tingent voltage, and the other for length of dip less than 70% of the same.

Is there a voltage dip minimum value that should not be exceeded for any length of time?

Does the voltage dip criteria apply to the FIDVR re-sponse plots as well? I would think so.

The initial voltage does not line up on Figure 2.

After reading the Technical Discussion, I disagree with the conclusions and resulting recommendations. Given that the P0-P7 events have different fault types, and given that the IEEE Standard 1668 has recommended criteria for different fault types, I disagree with the blan-ket approach to the recommended criteria of "not be-low 70% for more than 30 cycles for all P1-P7events." This is a fairly major departure from the criteria used currently, and it is not appropriate for all events in the P1-P7 range. In other words, the events that are speci-fied as 3-phase faults in the P1-P7 event definitions should adhere to the more stringent criteria recom-mended in IEEE 1668 of "not below 70% for more than 6 cycles," which also lines up better with the practices in place currently.

Issue 1: What does the third diagram cover? PendingIssue 2: Diagram 2 should only have two time spans: 1) length of voltage dip less than 80% of pre-contingent voltage, 2) length of dip less than 70% of the same.PendingIssue 3: Is there a voltage dip minimum value that should not be exceeded for any length of time?Pending




Issue 4: Does the voltage dip criteria apply to the FIDVR response plots as well?PendingIssue 5: Figure 2 does not line upPendingIssue 6: Disagrees with white paper conclusions

Pending

Puget Sound Energy In general we agree with the comments and recommendations of the LMTF.

For WR1.1.1, please specify that post transient voltage limits apply to the steady state powerflow post-contingency results and not the dynamic simulation settling voltage.

For Phase 2 composite load models, which model FIDVR, 10 seconds to recover to 80%, may not be long enough. 15 sec-onds may be more appropriate.

For WR1.1.2 consider revising the limits to 90 percent to 110 percent of nominal for P1-P7 events (post-contingency) or pro-vide a technical justification for limiting voltage to 105 percent post-contingency. An upper limit of 105 percent is too stringent for multiple contingencies.

The technical justification document includes two bullet points in the Proposed Criterion section. In comparing the bullet points to the graphs, it looks like the first bullet is applicable to delayed recovery and the second bullet is applicable to normal recovery. If this is the case, can it be clearly stated? If this is not the case, can the graphs be revised to include both criteria (i.e. Figure 1 does not include the 70% and 80% criteria of the sec-ond bullet and Figure 2 does not include the criteria of the first bullet).

Issue 1: WR1.1.1, please specify that post transient voltage limits apply to the steady state powerflow post-contingency results and not the dynamic simulation settling voltage.




PendingIssue 2: For Phase 2 composite load models, which model FIDVR, 10 seconds to recover to 80%, may not be long enough. 15 seconds may be more appropriate.Pending

Issue 3: WR1.1.2 / 110%Please see the response to WAPA Issue 1 wherein the language was changed for clarification.Issue 4: Clarify what bullets apply to / revise the graphsPending

BC Hydro BC Hydro appreciates the efforts of the WECC Performance Drafting Team in revising WECC Criterion TPL 001-WECC-CRT and posting it for comments.

BC Hydro has the following comments for your consideration:1.How would the frequency issue stated in TPL-001-WECC-CRT-2.1 Table W-1 be addressed, if at all? Should TPL-001-WECC-CRT include additional requirements and measures to specify acceptable off-nominal frequency deviations at BES buses, particularly in situations where islanding is an acceptable consequence of the disturbance being studied? 2.WR1.2 reads "Post-Contingency steady-state low voltage deviation at each applicable BES bus serving load (having no intermediate connection) shall not exceed eight percent for P1 events". Is there a glossary entry that explains what "BES bus serving load (having no intermediate connection)" means? 3.WR1.2 (and elsewhere): Is it necessary to indicate that the voltage levels being referred to are the positive sequence voltages from dynamic simulation and powerflow study results and not individual phase voltages when simulating single-phase or other unbalanced system conditions?4.WR1.2 should be reworded to make it clearer; suggested wording: "For P1 events, the Post-Contingency steady-state voltage shall not be less than 92% of the pre-contingency voltage at each applicable BES bus serving load (having no intermediate connection)". This would make it consistent with WR1.3, WR1.4 and WR1.5 that also make reference to "pre-contingency voltage". 5.Both WR1.3 and WR1.4 refer to transient stability voltage




response at applicable BES buses serving loads. Will there be any voltage requirement for non-load serving BES buses? 6.WR1.4 voltage dip requirements for a load serving BES bus for P1 to P7 events match those in IEEE Standard 1668 for single-and two-phase fault ride-through according to the associated white paper. However the majority of the events in P1, P3 and P6 are 3-phase disturbances. Wouldn't the WR1.4 requirement (not below 70% for 0.5 second for single- and two-phase faults) be too lenient for these 3-phase fault events based on the 3-phase fault ride through (not below 70% for 6 cycles) stated by the same IEEE source? 7.WR5 requires positive var margin at increased transfer and increased load for voltage stability assessment. The applicable power factors for each type of analysis should be stated for clarity. We suggest that the following be added to WR5: Transfer increases, should be achieved by scaling up the MW output levels on the sending end generators and scaling down the MW output levels on the receiving end generators or adding a unity power factor load. For load increase at each load bus, both the real and reactive powers should be scaled up using the same power factor of each applicable bus in the base cases.8.WR1.5: The Rationale for Requirement WR1.5 seems to be related to WR1.6. 9.WR2: In the Rationale for Requirement WR2, shouldn't the references to "R2" be changed to "WR2" to make it clear that those references are to the (WECC) TPL-001-WECC-CRT-3 and not to the NERC TPL-001-4? 10.Rationale for Requirement WR4: 1.If the term "cascading" used in this requirement does not have the same meaning as the NERC defined term "Cascading", perhaps a different word/phrase should be used. If found appropriate WR4: Change "…the potential for cascading or uncontrolled islanding" to "…the potential for subsequent unconstrained loss of multiple system elements or uncontrolled islanding". This would avoid giving the impression that the word "cascading" was the NERC-defined term "Cascading"11.For any fault, can all load be divided into two categories, (a) consequential (i.e., within the protection zone of the fault) and




(b) non-consequential (i.e., outside the protection zone of the fault)? If so, perhaps some confusion can be prevented by eliminating the double-negatives. For example, instead of saying that "the load loss is not non-consequential", simply say that "the load loss is not non-consequential"Minor Comments (typos/clarifications):

12.Rationale for Requirement WR1.2: Change "….including capacity or reactor switching…." To "….including capacitor or reactor switching…."

Issue 1: Addressing frequency issue in Table W-1

Pending

Issue 2: WR1.2 meaning of "BES bus serving load (having no intermediate connection)"

No, this project is not proposing a defined term. The phase “having no intermediate connection” means immediately adjacent with nothing in between.

Issue 3: WR1.2 (et al) Is it necessary to indicate that the voltage levels are the positive sequence voltages - and not individual phase voltages

Pending

Issue 4: WR1.2 Suggested rewording

Pending

Issue 5: WR1.3 and WR1.4 Will there be any voltage requirement for non-load serving BES buses?

Pending

Issue 6: WR1.4 Too Lenient/ IEEE 1668

Pending

Issue 7: WR5 Clarify power factors

Pending

Issue 8: WR1.5, the Rationale for Requirement WR1.5 seems to be related to WR1.6.

Requirement WR1.5 and 1.6 Rationale Box has been redrafted for clarity.

Issue 9: WR2 typo




The typo was corrected.

Issue 10: Rationale for Requirement WR4 – Clarify cascading

Pending

Issue 11: Can load be divided into two categories: 1) consequential, and 2) non-consequential / Double negatives

Pending

Issue 12: More Typos

See response to G2 Power, Issue 1.

MVWG These are the comments from the WECC MVWG Load Modeling Task Force (LMTF) based on a recent conference call and subsequent email discussions:

Comment 1: For WR1 1.1, Please specify that the post transient voltage limits apply to the steady state power flow post contingency result, not to the dynamic simulation settling voltage. These voltages may be significantly different, especially considering end-use load tripping modeled in dynamic simulations not modeled in steady state power flow simulations.Comment 2: (SCE, APS): For composite load model phase 2, which models FIDVR, 10 seconds to recover to 80% may not be long enough. The group suggests 15 seconds is more appropriate.

Comment 3: (PS, PG&E, PAC, CAISO, others) For WR1 1.1.2, 105 percent of nominal for P1-P7 is too low. Instead, we propose 110% for P1-P7.

Issue 1: WR1 1.1, Please specify that the post transient voltage limits apply to the steady state power flow post contingency result, not to the dynamic simulation settling voltage.

Pending

Issue 2: For composite load model phase 2, which models FIDVR, 10 seconds to recover to 80% may not be long enough. The group suggests 15 seconds is more appropriate.

Pending




Issue 3: WR1 1.1.2, 105% vs. 110%

Please see the response to WAPA Issue 1 wherein the language was changed for clarification.

Tucson Electric Tucson Electric

Applicability Comments:4.2.2 - This document applies only to Bulk-Electric System (BES) substations (sic) buses.Comment: Requirement WR4 references facility loading. Facility loading is not applicable to substation buses but to branch elements. The applicability to facilities section should be updated to reflect this reference.4.2.4 - Please define each of the buses listed in 4.2.4.1 through 4.2.4.4. It is not clear if this is excluding only fictitious buses necessary to model the referenced capacitors and reactors or if it is any bus that is connected to a capacitor or reactor.4.2.4.5 - This section should include buses included to model the bus between the line and transformer of transformer-terminated lines.Requirements and Measures comments:WR1 - Please include a new Table W-1.WR1.1.1 - Define "nominal." The rationale section indicates that "nominal" voltage may vary from entity to entity but it does not indicate if it can vary within an entity. Does nominal carry across the system or can it vary on a bus by bus basis?WR1.3 - Please clarify "BES buses serving load (having no intermediate connection)". It is not clear if the load serving bus is the bus the load serving transformer is connected to or is it the bus that the feeder on the load side of the transformer is connected to. Per the BES definition BES is only 100kV or above unless inclusion/exclusion criteria is met and the low-side bus of a load-serving transformer does not typically meet the inclusion criteria.WR1.4 - "or remain below 80% of pre-contingency voltage for more than two seconds for all P1-P7 category events." This is inconsistent with WR1 1.3which allows recovery to 80% of pre-contingency voltage within 10 seconds for all P1-P7 category events.WR1 1.3 and WR1.4 - Develop a new finger diagram and include




durations allowed on the finger diagram.Rationale for WR1.5 This appears to be additional rationale for WR1.6. There is no reference to a 30-second time frame in WR1.5 but there is in WR1.6.WR4 - Since cascading is not the NERC defined term, please use a different term to avoid confusion.

WR4, 1st Bullet - "or exceeds 125% of the highest applicable facility rating." If the trip setting is known (and it should be known for your own facilities) then the trip setting should be used. The 125% threshold should only be used for facilities where the trip setting is not known. If the known trip setting is 150% of the continuous rating, this should take precedence over the 125% of the highest rating. WR5.1 through WR5.4 - Make the language consistent with the WECC Guide to WECC/NERC Planning Standards I.D: Voltage Support and Reactive Power. Otherwise, it looks like both a flow margin and a load margin must be studied and regroup so that transfer path requirements are together and load area requirements are together as shown below:WR5.1 For transfer paths, all P0-P1 events shall demonstrate a positive reactive power margin at a minimum of 105 percent of transfer path flow.WR5.2 For transfer paths, all P2-P7 events shall demonstrate a positive reactive power margin at a minimum of 102.5 percent of transfer path flow.WR5.3 For load areas, all P0-P1 events shall demonstrate a positive reactive power margin at a minimum of 105 percent of forecasted peak load.

WR5.4 For load areas, all P2-P7 events shall demonstrate a positive reactive power margin at a minimum of 102.5 percent of forecasted peak load.

Issue 1: 4.2.2 - This document applies only to Bulk-Electric System (BES) substations (sic) buses.

The facilities section has been revised as follows. Typographical errors will be further scrutinized during technical writing.

4.2. Facilities:




4.2.3. This document applies to Bulk Electric System (BES) substations buses.

4.2.4. Each of the following elements is specifically excluded from this Crite-rion:

4.2.4.1. Non-BES buses.

4.2.4.2. Line side series capacitor buses

4.2.4.3. Line side series reactor buses

4.2.4.4. Dedicated shunt capacitor buses

4.2.4.5. Dedicated shunt reactor buses

4.2.4.6. Metering, fictitious, or other points of interconnection mod-eled solely for measuring electrical quantities; and,

4.2.4.7. Other buses specifically excluded by each Planning Coordinator or Transmission Planner internal to their system.

Issue 2: WR4 references facility loading. Facility loading is not applicable to substation buses but to branch elements. The applicability to facilities section should be updated to reflect this reference.

Pending

Issue 3: WR4.2.4 - Define each of the buses listed in 4.2.4.1 through 4.2.4.4. Clarify: Does this exclude only fictitious buses necessary to model the referenced capacitors and reactors or if it is any bus that is connected to a capacitor or reactor?

Pending

Issue 4: WR4.2.4.5 - This section should include buses included to model the bus between the line and transformer of transformer-terminated lines.

Pending

Requirements and Measures comments:

Issue 5: WR1 - Please include a new Table W-1.

Pending

Issue 6: WR1.1.1 - Define "nominal." Does nominal carry across the system or can it vary on a bus by bus basis?

The use of the term nominal cares its generic definition as contained in the dictions.

Pending




Issue 7: WR1.3 - Please clarify "BES buses serving load (having no intermediate connection)".

Pending

Issue 8: WR1.4 – Not sure what they want???

Pending

Issue 9: WR1 1.3 and WR1.4 - Develop a new finger diagram and include durations allowed on the finger diagram.

Pending

Issue 10: WR1.5 Rationale –relocate to WR1.6?

Clarified.

Issue 11: WR4 – Don’t use “c”ascading – use a different word

Pending

Issue 12: WR4, 1st Bullet

Pending

Issue 13: WR5.1 through WR5.4 - Make the language consistent with the WECC Guide to WECC/NERC Planning Standards I.D: Voltage Support and Reactive Power.

Pending

Issue 14: WR5.1 through 5.4 – Suggested Redraft

Pending

NV Energy Comment 1:

Requirement WR1 states:Each Transmission Planner and Planning Coordinator shall use the following base criteria in its Planning Assessment, unless otherwise specified in accordance with Requirements WR2 and WR3.WR2 ensures that if planning entities use a more stringent requirement than WR1, they cannot impose that requirement




on other systems.WR3 ensures that if planning entities use a less stringent requirement than WR1, they shall allow other planners to have the same impact on the part of the systemBased on the wording of WR1, it is implied that exceptions to the criteria are allowed, but not explicitly stated. The wording in WR1 should be re-worded to include the allowance of exceptions to the requirements.Comment 2:We recommend that 10% should be used in requirement WR1.2 instead of 8%. This is based on the many years of experience of using 10% successfully. In addition, for today's power system and the new modeling tools (specifically enhancing ability to perform transient and voltage stability analysis) the meaning of having a specific limit on the voltage deviation is not very significant. There's no proof that an 8% limit would guarantee that the system remains stable and no load loss occurs while 10% wouldn't.Comment 3:Requirement WR1.3 states:Transient stability voltage response at applicable BES buses serving load shall recover to at least 80 percent of pre-contingency voltage within 10 seconds of the initiating event for all P1-P7 category events.The white paper discussing the rationale for this states that "Based upon past experience and sound engineering judgment it is proposed that the voltage must recover to at least 80% of the pre-disturbance voltage. Even though there is no hard technical justification for 80%, it is widely understood that if the voltage did not recover to at least 80%, there could be unintended consequences such as protection system Misoperation which could result in cascading. In addition, recovering in a maximum of 10 seconds seems like a reasonable time to recover during a FIDVR event based on experience and engineering judgment. " The voltage recovery of 80% could, however, potentially affect relay loadability of a transmission line based on the calculations used in PRC-023. Based on the technical reference paper Fault-Induced Delayed Voltage Recovery issued by the NERC Transmission Issues




Subcommittee and System Protection and Control Subcommittee, Section 5 specifically addresses system protection considerations to address the FIDVR phenomenon. In short, PRC-023 requirements R1.1 and R1.2 are calculated so that transmission line relays do not operate at or below a certain percentage of the circuit rating. The calculation is based on 0.85 pu voltage rating. If the voltage is allowed to recover to at least 80%, then the relay loadability rating will be decreased beyond what was calculated (If R1.1 was chosen to have a loadability rating of 150% at 0.85 pu voltage, then the rating goes down to 141% at 0.80 pu voltage).

Since there is no hard technical justification for using 80%, perhaps it should be changed to 85% to avoid decreasing the relay loadability and to correspond with relay loadability calculations in PRC-023

Issue 1: Requirement WR1 states:

See response to WAPA, Issue 4.

Issue 2: WR1.2 10%

See response to WAPA, Issue 1.

Issue 3: WR1.3 80% recovery – change to 85% to correspond with PRC-023

Pending

Platte River PRPA is in agreement and support of Western Area Power Administration's comments. Thanks!

Thank you. Please see responses to WAPA.

Salt River Project We would like to avoid ambiguity and misunderstanding about which are the BES buses that serve load. We recommend clarifying them as follows:

1.BES bus serving load is the bus with direct transformation from BES level voltage to distribution level voltage that serves customer load. 2.BES bus serving load does not constitute bus with direct transformation to a bus serving generation auxiliary load.




We feel this will provide a little bit more clarity for the requirement 1.4.

Issue 1: WR1.4 No Intermediate – suggested language

Pending

Seattle City Light Thank you for the opportunity to comment. Here are comments from SCL.

In Applicability 4.2.3, do not use the term "Western Interconnection" because it is not a NERC defined term. This came up in discussions when talking about FAC-010, and we would like to pass this on to this drafting team as well.

Regarding WR1.1.2, it is recommended to increase the high voltage limit to either 110 percent for P1-P7 events as used in the previous criteria or something that is at least higher than 105 percent, perhaps considering the equipment capabilities. Equipment ratings are typically the limiting factor for high voltage limits and they are typically higher than 105 percent of the base voltage. For example, typical 230kV equipment is rated by the manufacturer for a maximum voltage of 245kV and for 115kV equipment to be rated for a maximum voltage of 123kV. The actual per unit rating is different for each voltage level, but both are fairly close to 1.065pu. Please also consider that the high voltage limit for P1-P7 would be appropriately higher than P0 (system normal). Perhaps there is a place for duration based emergency ratings for voltage, as there are for thermal ratings.

Issue 1: Applicability 4.2.3, do not use the term "Western Interconnection"

This language was removed from the Applicability section and the following statement added below the purpose statement.

“This document applies to all transmission planning studies conducted within the Interconnection of the Western Electricity Coordinating Council (WECC).”

Issue 2: WR1.1.2. 110%

Please response to WAPA Issue 1.




Pacific Gas and Electric WR1.2 and 1.3

Please clarify what "having no intermediate connection" means.WR1.5 and 1.6The Rationale for requirement box above WR1.6 appears to be addressing rationale for WR1.5 and WR1.6. To avoid confusion, please split the rationale into two boxes, one for each requirement.WR2WR2 and the rationale for WR2 does not clearly identify the use of a more stringent criteria developed by a planning entity by others. According to the language in the document, "The rationale for Requirement R2 is to ensure that Planning entities do not impose more stringent requirements on systems other than their own. It may use more stringent criteria on its system but may not impose more stringent criteria on others." Does it mean that if a planning entity develops a more stringent requirement for its system, other planning entities are not required to use the same criteria on that part of the system for the same category of planning events?WR41. The first bullet states that, "when a post contingency analysis results in a facility loading that is either in excess of a known BES facility trip setting, or exceeds 125% of the highest applicable facility rating for the BES facility studied." To add clarity, please include the rationale for the use of 125% of the highest facility rating and how it relates to the PRC standard.

2. The terms "unrestrained successive load loss" and "unrestrained successive generation loss" in the third bullet are not defined. Please include a short description of these two terms in the rationale for this requirement.

Issue 1: WR1.2 and 1.3 - Please clarify what "having no intermediate connection" means.

Pending

Issue 2: WR1.5 and 1.6

Please see response to Tucson Electric Issue 10.

Issue 3: WR2 Rationale Box – “Does it mean that if a planning entity develops a more stringent requirement for its system, other planning entities are not required to use the same criteria on that part




of the system for the same category of planning events?”

Pending

Issue 4: WR4, Bullet 1, include the rationale for the use of 125%

Pending

Issue 5: WR4, Bullet 3 - Include a description of the terms "unrestrained successive load loss" and "unrestrained successive generation loss"

Pending

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