Comment Report Form for WECC Standard VAR-001-WECC-1 – Voltage and Reactive Control
WECC-0071
Posting 1 Responses
Open: March 23, 2011
Closed: May 19, 2011
Comment Report Form
WECC Criteria TPL-001-WECC-CRT-1 – System Performance Criterion
The WECC-0071 (TPL-001-WECC-CRT-2 System Performance Criterion) Criterion Drafting Team thanks everyone who submitted comments on the TPL-001-WECC-CRT-2 System Performance Criterion. This criterion was posted for a 45-day public comment period from March 23, 2011 through May 9, 2011. WECC distributed the notice for this posting on March 22, 2011. The drafting team asked stakeholders to provide feedback on the criterion through a special Criterion Comment Form. WECC received comments from seven companies representing three of the 10 Industry Segments, as shown in the table on the following pages.
In this “Consideration of Comments” document, stakeholder comments have been organized so that it is easier to see the responses associated with each question. All comments received on the standard can be viewed in their original format at:
http://www.wecc.biz/Standards/Development/WECC-0071/Lists/WECC0071%20%20TPL%20%20001%20%20WECC%20%20CRT%20%202%20%20System%20Performan/AllItems.aspx.
If you feel that your comment has been overlooked, please let WECC know immediately. WECC’s goal is to give every comment serious consideration in this process. If you feel there has been an error or omission, please contact the Director of Standards, Steve Rueckert at . In addition, there is a WECC Reliability Standards Appeals Process.[1]
The Industry Segments are:
1 — Transmission Owners
2 — RTOs, ISOs
3 — Load-serving Entities
4 — Transmission-dependent Utilities
5 — Electric Generators
6 — Electricity Brokers, Aggregators, and Marketers
7 — Large Electricity End Users
8 — Small Electricity End Users
9 — Federal, State, Provincial Regulatory or other Government Entities
10 – Regional Reliability Organizations, Regional Entities
Commenter / Organization / Industry Segment /1 / 2 / 3 / 4 / 5 / 6 / 7 / 8 / 9 / 10 /
1. / Peter Krzykos
Engineering Supervisor, Transmission Planning and Engineering
Bajarang Agrawal
Engineering Manager, Technical Projects Engineering
Jonathan Stahlhut
Engineer III, Transmission Planning and Engineering / Arizona Public Service Company / ü
2. / Brian K. Keel / SRP / ü
3. / Andrew J. Meyer, PE / Tucson Electric Power Co. / ü
4. / John Cummings / PPL Energy Plus / ü
5. / Aaron Paulson
Submitted on behalf of following SME's, ChuckMatthewsand Rebecca Berdahl / BonnevillePower Administration / ü
6. / Bill Pascoe / Consultant for TransWest Express / ü
7. / Dave Hagen / PacifiCorp / ü
Index to Questions, Comments and Responses
Question / Page1. Do you agree that there is still a need for adjacent circuit criteria that is more stringent than the NERC Planning Standards? Yes/No. If you answered yes to the above question, please provide reasons why you support the need. If you answered no, please explain your answer and provide the technical justification in support of your answer. / 4
2. Do you agree with changing the separation distance between structure center lines in the proposed Adjacent Transmission Circuit definition to 250 feet from the 500 feet or the length of the longest span in the Common Corridor definition? Yes/No. If yes, please provide reasons why you support the change. If no, please provide reasons why you disagree with the change and propose refinements to criterion and associated definition. / 5
3. Do you agree with the change to make requirement WRS1.1 apply to only Adjacent Transmission Circuits that are both 300 kV or greater? Yes/No. If yes, please provide reasons why you support the voltage limit. If no, please explain what refinements should be made and why. / 5
4. Do you agree with excluding circuits from complying with requirement WRS1.1 when the circuits on separate towers are adjacent for less than two miles to allow for substation entrances, pinch points, and river crossings? Yes/No. If yes, please provide reasons why you support the two mile limit. If no, please provide a recommendation on how the provision should be changed. Please provide technical justification for your recommendation. / 7
5. Do you agree with the drafting team that it is appropriate to remove and retire the definition for Common Corridor? Yes/No. If yes, please provide reasons why you support the removal. If no, please explain why you believe a definition for Common Corridor should be retained. / 8
6. Will the number of Adjacent Transmission Circuits in your transmission system that are required to be studied and mitigated with a higher performance level be reduced because of the refinements proposed in TPL-001-WECC-CRT-2? Yes/No. If yes, please provide the number of Adjacent Transmission Circuits that will no longer be held to the previous performance level and the number of Adjacent Transmission Circuits that will still be held to the higher performance level. If no, please provide the number of Adjacent Transmission Circuits that will still be held to the higher performance level. / 10
7. Do you believe that the refinements proposed in TPL-001-WECC-CRT-2 will reduce reliability? Yes/No. If yes, please explain what impact to reliability that the refinements will cause. In addition, recommend refinements to the criteria that would address your concerns. If no, please explain why reliability in the Western Interconnection will not be reduced. / 10
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Comment Report Form for WECC Standard VAR-001-WECC-1 – Voltage and Reactive Control
1. Do you agree that there is still a need for adjacent circuit criteria that are more stringent than the NERC Planning Standards? Yes/No. If you answered yes to the above question, please provide reasons why you support the need. If you answered no, please explain your answer and provide the technical justification in support of your answer.
Summary Consideration:
Commenter / Yes / No / Comment /Arizona Public Service Company
Peter Krzykos
Engineering Supervisor, Transmission Planning and Engineering
Bajarang Agrawal
Engineering Manager, Technical Projects Engineering
Jonathan Stahlhut
Engineer III, Transmission Planning and Engineering / No / The NERC Planning Standards cover the appropriate contingencies that should be studied in the Planning Horizon. There is no evidence that the adjacent lines in WECC have higher probability of simultaneous outage compared to other interconnection. There is no reason for WECC to have this additional requirement.
Response: WECC has been collecting data on common mode outages for transmission systems 200 kV and above; e.g., common tower vs. common corridor separate tower. To date, two years of data have been analyzed. While the probability of a common corridor is similar or within an order of magnitude of the common tower outage rate, there are no outage data to demonstrate that the TPL-001-WECC-CRT-2-System Performance Criteria should be removed. At this time the drafting team is hesitant to remove the criteria based upon the limited data. Since the outage data are limited, the Reliability Subcommittee will continue to review the outage data to determine whether the outage data would support refinements to the current criteria. The drafting team is preparing a report that will provide the analysis from the WECC outage data.
Brian K. Keel
SRP
/ Yes / I think it is still appropriate criteria to use because of the line lengths and environments.
Response: Thank you.
Andrew J. Meyer, PE
Tucson Electric Power Co.
/ No / Adjacent circuits on separate towers do not need to be evaluated using more stringent criteria as TEP evaluates all double contingencies regardless of whether they have a common mode.
Response: WECC has been collecting data on common mode outages for transmission systems 200 kV and above; e.g., common tower vs. common corridor separate tower. To date, two years of data have been analyzed. While the probability of a common corridor is similar or within an order of magnitude of the common tower outage rate, there are no outage data to demonstrate that the TPL-001-WECC-CRT-2-System Performance Criteria should be removed. At this time the drafting team is hesitant to remove the criteria based upon the limited data. Since the outage data are limited, the Reliability Subcommittee will continue to review the outage data to determine whether the outage data would support refinements to the current criteria. The fact that TEP runs more double contingencies than the required is noted as the criteria and NERC standards contain minimum requirements. The drafting team is preparing a report that will provide the analysis from the WECC outage data.
John Cummings
PPL Energy Plus
/ No / The drafting team has made an effort to make this criteria (TPL - (001 thru 004) – WECC – CRT-2-System Performance Criteria (“Criteria”)) less strict than currently in-place in the WECC. PPL requests that the drafting team go even further and retire these Criteria and use only NERC Table 1 for planning in the west. PPL is concerned that these Criteria will actually reduce reliability by making it more difficult to site and build new transmission lines. If the Criteria are not retired, PPL has the following questions that the drafting team should answer to justify keeping these unique “west-only” Criteria.
1.What technical aspects of the western Bulk Electric System are so unique from the east that it justifies each of the more stringent Requirements of these Criteria?
2.Can the drafting team please use benefit/cost analysis to justifying the more restrictive, west-only Criteria in order to explain why the west-only criteria is better than other methods to compensate for those unique west-only characteristics?
3.In what specific way(s) does the NERC Table 1 fail to protect the Bulk Electric System in the west and what is the chance this will affect reliability in the west?
Response: WECC has been collecting data on common mode outages for transmission systems 200 kV and above; e.g., common tower vs. common corridor separate tower. To date, two years of data have been analyzed. While the probability of a common corridor is similar or within an order of magnitude of the common tower outage rate, there are no outage data to demonstrate that the TPL-001-WECC-CRT-2-System Performance Criteria should be removed. At this time the drafting team is hesitant to remove the criteria based upon the limited data. Since the outage data are limited, the Reliability Subcommittee will continue to review the outage data to determine whether the outage data would support refinements to the current criteria. The drafting team is preparing a report that will provide the analysis from the WECC outage data.
Aaron Paulson BonnevillePower Administration
360-418-8687
Submitted on behalf of following SME's, ChuckMatthewsand Rebecca Berdahl / Yes / There are major paths between sub-regions within the Western Interconnection where an outage of two adjacent circuits (greater than 300 kV) could result in a major disturbance that would affect multiple sub-regions within WECC. Planning of major new transmission lines (greater than 300 kV) needs to consider this impact.
There are also two general comments regarding the proposed criteria. The terms “frequency”, “event frequency”, “event outage frequency”, and “mean time between failure” are used interchangeably throughout the document (WRS1.1, WRS1.4, WRS 5, WMS6, and in the table). Consistency or clarification is needed to indicate that these terms all imply “mean time between failure”. Preferably only one term (such as MTBF) should be used throughout the document to avoid any confusion.
Clarification is needed regarding event frequency determination in WRS1.1 and performance category adjustment in WRS1.4. Specifically, it needs to be clarified that each utility determines the event frequency for WRS1.1 if there is more than 30 years of historical data, and if there is less than 30 years of historical data WRS1.4 requires Board approval for a performance level adjustment, a utility.
Response: The drafting team will look into consistent language within the scope of this project. The recommendations in this comment are outside the scope of the current project standard request. Implementing the recommendations in the second and third paragraphs will have to be addressed in subsequent project for refinements to these criteria.
Bill Pascoe
Consultant for TransWest Express
/ No / The risk of a simultaneous N-2 outage involving circuits on separate structures is sufficiently small that a requirement significantlymore stringent than the NERC Planning Standards is not warranted.
Response: WECC has been collecting data on common mode outages for transmission systems 200 kV and above; e.g., common tower vs. common corridor separate tower. To date, two years of data have been analyzed. While the probability of a common corridor is similar or within an order of magnitude of the common tower outage rate, there are no outage data to demonstrate that the TPL-001-WECC-CRT-2-System Performance Criteria should be removed. At this time the drafting team is hesitant to remove the criteria based upon the limited data. Since the outage data are limited, the Reliability Subcommittee will continue to review the outage data to determine whether the outage data would support refinements to the current criteria. The drafting team is preparing a report that will provide the analysis from the WECC outage data.
Dave Hagen, PacifiCorp / PacifiCorp appreciates the effort the WECC-0071 drafting team has made in the development of the TPL– (001 thru 004)–WECC–CR–2 proposal.
The drafting team’s charter was to propose revisions to Requirement WRS1.1 that would permit more efficient use of rights-of-way while promoting the use of separate towers instead of multi-circuit towers while maintaining an acceptable level of reliability for the Western Interconnection. We believe the proposed revisions have that effect and support these changes. However, PacifiCorp would like to make a general comments and recommendations.
The present NERC standard and WECC criteria require Category D events to be studied including loss of all lines in a corridor. No specific performance is mandated; rather, these events are evaluated for risk and consequence. While the proposed revisions are helpful in the sense that the demonstrable improvement in reliability for adjacent circuits on separate structures is recognized, these changes make it even more important that the risk associated with multiple high capacity circuits in close proximity be more strongly addressed than is presently the case.
There is general recognition that the most cost effective preemptive strategy against the simultaneous loss of multiple transmission lines involves ensuring adequate separation distance between lines at the planning stage. Unfortunately it is also very difficult to convince the public and regulatory agencies/bureaus that the consequence of loss of all lines in a corridor due to fire, storms, or other extreme but low probability events is significant enough to justify the cost and environmental impact of wider or multiple corridors. Instead, the general sentiment is to push more and more lines into close proximity regardless of the perceived risk. And the proposed changes to the WECC criteria may, over time, result in even more parallel lines in the same corridor than would be the case with the existing criteria.
Therefore PacifiCorp requests that the drafting team consider further changes to the WECC criteria that limit the amount of capacity that can be in the same corridor, or find some other mechanism to strengthen our collective ability to provide adequately separation where multiple high capacity lines are planned for the same parallel corridor. This is particularly important for long DC lines and AC lines at or above 500 kV. In addition TPL-004 events analysis and risk assessments should be required and documented as part of the Three Phase Rating Review Process to ensure that all interconnected parties agree to and understand the consequences of “Category D” events.
Response: The intent of the current criteria request is to look at the difference between common tower and adjacent circuits on separate towers. The comment goes beyond the intent of the current criterion request. The drafting team believes this comment would be more appropriate in a separate standard request or should be vetted in other forums.
2. Do you agree with changing the separation distance between structure center lines in the proposed Adjacent Transmission Circuit definition to 250 feet from the 500 feet or the length of the longest span in the Common Corridor definition? Yes/No. If yes, please provide reasons why you support the change. If no, please provide reasons why you disagree with the change and propose refinements to criterion and associated definition.