Comment Report Form forWECC-0101
Variance to MOD-026-1
Verification of Models and Data for Generator Excitation Control System or Plant Volt/VAR Control Function
Variance to MOD-027-1
Verification of Models and Data for Turbine/Governor and Load Control or Active
Power/Frequency Control Functions
The WECC-0101 Variance Drafting Team (AKA: Generator Validation Conversion Drafting Team) (DT) thanks everyone who submitted comments on the proposed documents.
Posting
This document was last posted for a30-day public comment period fromJuly 29, 2014 through August 29, 2014.
WECC distributed the notice for the posting onJuly 25, 2014 with a reminder distributed on August 21, 2014. The DT asked stakeholders to provide feedback on the proposed document through a standardized electronic template.WECC received comments from11 companies representingfive of the eight Industry Segments, as shown in the table on the following page.
Location of Comments
All comments received on the document can be viewed in their original formathere.
Changes in Response to Comment
Section references contained in these responses are subject to change. Unless otherwise specified, parallel changes will be made to both MODs.
After consideration of comments received, the WECC-0101 Generator Validation Conversion Drafting Team (DT) made the following changes to Posting 1 for reconsideration during subsequent postings:
Effective Date
The Effective Date was: 1) modified to apply equally to both digital and non-digital units, 2) modified extending the hard-coded dates thereby acknowledging that the time-lines of the underlying standards have already begin to run, 3) an additional compliance tier of 75% was added between 50% and 100%.
The Effective Date now reads (similarly for both standards):
5.Effective Date
The Effective Date of Section 5.2, 5.3 and 5.4 are replaced in their entirety as follows:
5.2For 30% of an entity’s applicable-unit gross MVA, the Effective Date is the latter of either July 1, 2019, or Applicable Regulatory Approval.
5.3For 50% of an entity’s applicable-unit gross MVA, the Effective Date is the latter of either July 1, 2020 or Applicable Regulatory Approval.
5.4For 75% of an entity’s applicable-unit gross MVA, the Effective Date is the latter of either July 1, 2021 or Applicable Regulatory Approval.
5.5For 100% of an entity’s applicable-unit gross MVA, the Effective Date is the latter of either July 1, 2022 or Applicable Regulatory Approval.
Different Treatment for Digital and Non-Digital
This difference was removed. The document now applies to both digital and non-digital equally.
Sampling Rate
The sampling rate is no addressed in either MOD-26 or MOD-27. Suggestions to change the sampling rate proposed in the variance were accepted. The DT adopted the approach that minimum sampling should be 10 times per second or 10 times the measured bandwidth of the control system if the bandwidth of the control system is less than 1 Hz.
For MOD-026, this results in a sampling rate of 30 samples per second or higher. For MOD-027 the following language is added at E.B.2.1.6:
3) Recorded signal shall have a minimum sampling rate of 10 times per second or 10 times the measured bandwidth of the control system if the bandwidth of the control system is less than 1 Hz.
Clarification
At MOD-26, E.B.2.1.7., the DT added phrasing to clarify the language addressed real and reactive power output.
Cost-Benefit Analysis
The DT concluded it was not in the best position to perform a cost-benefit analysis on the proposed variance. The DT agreed to invite the industry to provide its comments on the actual costs of the proposed variance and let the data speak for itself.
Periodicity of Revalidation
The DT agreed that language could be added to lessen the administrative burden and require action only when permanent changes were made to the system. The DT made the following change:
MOD-026
E.B.4Each[SP1] Generator Owner shall provide to its Transmission Planner revised model and validation data, to include each of the below numbered items, each time a permanent change is made to the operating characteristics of its generator or excitation control system, within 30 days [SP2]of making that permanent change. [Violation Risk Factor: Lower] [Time Horizon: Operations Planning]
1)Generator open circuit saturation
2)Steady-state generator output power, reactive power, voltage, generator field current and voltage at stated operating point (i.e. V-curves)
3)Inertia
4)Synchronous machine impedances and time constants
5)Automatic Voltage Regulator
6)Power system stabilizer
7)Over-excitation limiter
8)Under-excitation limiter
9)Reactive power compensation
M.E.B.4Each Generator Owner will have evidence that it provided to its Transmission Planner revised model and validation data, to include each of numbered criteria in Requirement E.A.4, each time a permanent change is made to the operating characteristics of its generator or excitation control system, within 30 days of making that permanent change, as required in Requirement E.A.4.
For auditing purposes a permanent change is any alteration in operating characteristics extending beyond 30 days, and specifically excludes changes in operating characteristics resulting during routine maintenance or unique operating circumstances lasting less than 30 days.
Evidence may include, but is not limited to:
- Dated documentation communicating to the Transmission Planner the operating characteristics existing prior to and after the permanent changes were implemented;
- Dated documentation communicating to the Transmission Planner the Generator Owner’s plan to leave the changes in place longer than 30 days.
Load Rejection
For MOD-27, the DT has previously proposed to strike the reference to load rejection tests from the document. The DT reconsidered. The load rejection language will be retained.
Minority Comments Summary
- The DT disagreed with APS that the variance was not needed. The variance is needed to address a data shortfall occurring prior to the trigger events on the underlying MODs.
- The Applicability threshold remains the same as the Bulk-Electric System (BES). The BES threshold proposed is higher than the existing WECC Generator Unit Modeling Validation Policy (Policy). The NERC drafting team that created the underlying MODs indicated that 80% of WECC members were already compliant at the lower thresholds of the GUMV Policy; thus, using the BES threshold should not impose undue burden or surprise. Finally, the existing threshold contained in the approved MODs was not the result of any one single technical study; rather, it was a distillation of many studies reviewed by the industry resulting in industry consensus. By comparison, the proposed thresholds reflect the results of the well-vetted BES proceedings buttressed by an even more stringent threshold as adopted by the nearly 200-members of the WECC Planning Coordination Committee (PCC).
- Changes the WECC Policy fall to the PCC and not to the DT.
- For purposes of compliance, the use of a pre-existing WECC certification issued under the WECC Policy will not be accepted because the certificate could predate any changes to the system.
- The DT notes that a technical study was not conducted to support the existing 75 MVA threshold. Rather, that number was set as an estimation threshold to include 80% of the Interconnection’s units. As proposed the variance would adopt the BES Threshold relying on the depth of the expertise that went into that proceeding.
- Although the DT agreed that an informal communications process should exist between the Generator Operator and the Transmission Planner, creation of that process was outside the scope of this project and would be better addressed at the WECC Standing Committee level.
- The DT declined the opportunity to interpret the meaning of the BES definition; however, it suggested that its intent was to include Synchronous Condensers in the applicability of the variance(s).
Action Plan
The DT will request that the WECC Standards Committee post these responses. Further, the DT will request that Posting 3 of this project be provided to the industry for comment.
Sections such as the Violation Severity Levels and Violation Risk Factors will be updated after the Requirements are further developed.
Contacts and Appeals
If you feel your comment has been omitted or overlooked, please contact the Manager, WECC Standards Processes, W. Shannon Black, at addition, there is a WECC Reliability Standards Appeals Process.[1]
The WECC Standards Voting Sectors are:
1 — Transmission Sector
2 — Generation Sector
3 — Marketers and Brokers Sector
4 — Distribution Sector
5 — System Coordination Sector
6 — End Use Representative Sector
7 — State and Provincial Representatives Sector
8 — Other Non-Registered WECC Members and Participating Stakeholders Sector
Commenter / Organization / WECC Standards Voting Sectors1 / 2 / 3 / 4 / 5 / 6 / 7 / 8
1 / Janet Smith / Arizona Public Service Company / X / X / X / X / X
2 / Alex Chua / Pacific Gas and Electric / X / X / X / X / X
3 / Jim Miernyk / PacifiCorp / X / X / X / X / X
4 / Pamela Hunter / Southern Power Company[2] / - / - / - / - / - / - / - / -
5 / Hamid Zakery / Calpine Company / X
6 / Edwin Tso / Metropolitan Water District of Southern California / X
7 / Leland McMillian / PPL Montana, LLC / X / X
8 / Cain Braveheart / Bonneville Power Administration / X / X / X / X
9 / David Lemmons / Xcel Energy / Public Service Company of Colorado / X / X / X / X / X
10 / Joshua Anderson / Salt River Project / X / X / X / X / X
11 / Eric Bakie / Idaho Power / X / X / X
Index to Questions, Comments, and Responses
Question
- The drafting team invites comments on all aspects of the proposed variances. Please be specific as to which document your comments should apply: 26 or 27.
- 1 -
1.The drafting team invites comments on all aspects of the proposed variances. Please be specific as to which document your comments should apply: 26 or 27.
Summary Consideration: / See summary in the preamble of this document.Commenter / Yes / No / Comment
APS / Since the current NERC standard already takes into account variation on the impact of generator size in relation to the interconnection, AZPS does not believe that there is a need for the suggested variance nor is the variance technically justified. Creating a variance to an industry developed NERC Standard, including significant WECC participation, should require a demonstrable need for the variance and not simply a continuation of current policy. Additionally, AZPS does not see where our comments from the previous comment period were addressed. We have included our previous comments for your convenience.
Question: Do you agree with the change in the applicable facility threshold?
Comments: No, AZPS supports the need for accurate generator model information and we value the work done by the MOD-026-1 and MOD-027-1 drafting teams. We believe significant attention was paid to developing the applicability limits as demonstrated by the variation across interconnections.
AZPS does not believe there has been sufficient, if any, technical justification for the revised, more stringent applicability threshold. Creating a variance to a NERC standard should require that a demonstrable need for the variance exists and is not simply reflective of continuing a current policy.
Question: Do you agree with the change in the Effective Dates?
Comments: No, AZPS supports the need for accurate generator model information. However, we believe there is very limited benefit to creating a variance to require analog units to be tested every five years. The population of analog units is small and decreasing as units are upgraded or retired. AZPS believes that it is not appropriate to pursue a variance unless a technical justification for the variance has been demonstrated. It should not simply be a continuation of an existing policy.
Issue 1: The need for a Variance
APS suggests it finds no need for the proposed Variance. The DT disagrees.
Unlike the underlying NERC Standards, the proposed WECC Variance(s) addresses more than just re-validation of units. The charge of the Standards Authorization Request (SAR), among other things, was to review the WECC Generating Unit Model Validation Policy (GUMVP) to determine the content of the proposed variance.
Under the existing MOD 26/27, only review and re-validation of data are addressed. Neither document addresses the initial baseline validation of data as proposed in the variances. This concept of initial validation contained in the GUMVP (predominately in Section 2) has been in place within WECC for over a decade and forms a voluntary foundation upon which enhanced modeling accuracy has been built. The proposed variance will change the data collection from voluntary to mandatory thereby enhancing the accuracy of the models and the subsequent operation of the grid upon which those models are based.
Without the variance, WECC has less reliable information regarding units more recently placed into service as well as older units, the equipment of which has been altered prior to the mandated revalidation covered by the existing NERC Standards or of which has never been validated.
Finally, the DT suggests that methodology proposed in the variance is more accurate (more granular) than that required under the NERC Standards.
Issue 2: Addressing Previous Comments – Contact WECC.
APS states it does not see where its comments from the previous comment period were addressed. WECC would remind APS and all industry entities to contact WECC as soon as practical after reaching such a conclusion. To assist the industry in assuring its comments are considered, each Response to Comment form produced by each drafting team contains the following information:
“Contacts and Appeals
If you feel your comment has been omitted or overlooked, please contact the Manager, WECC Standards Processes, W. Shannon Black, at . In addition, there is a WECC Reliability Standards Appeals Process.[3]”
That said, the DT notes that it did address APS’ comments in the Posting 1 Response to Comments document.
The team’s response was the same as it was for the Metropolitan Water District. Responses to Comments received in Posting 1 (as with all WECC drafting teams) are posted in the Team Site Development Table in the column titled “Responses to Comments.”
Issue 3: Applicability Threshold – PCC approved
The DT notes the commenter’s concern as to the change in the applicability threshold. If accepted, the change would lower the individual generator MVA threshold down from 75 MVA (as required in the current MOD-026 and MOD-027) to 20 MVA for individual generators thereby matching the definition of the Bulk-Electric System (BES). The DT notes the proposed threshold is still higher than the currently approved GUMV Policy, in effect since July 2006, that states:
A.3.Applicability
A.3.1.Facilities Affected: This policy statement applies to generating facilities connected to the [WECC] transmission grid at 60 kV or higher voltage (both new and existing, synchronous and non-synchronous) with single unit capacity of 10 MVA and larger, or facilities with aggregate capacity of 20 MVA and larger.” Policy, A.3.Applicability
Under the WECC Document Categorization Policy, the Policy applies to WECC members and is currently subject to adherence and monitoring. As such, it is presumed that WECC members are already using the lower Policy threshold for modeling purposes than is proposed under the BES definition and as approved under the existing standards. Thus, there should be no new burden or undue surprise.
This conclusion is further buttressed in the WECC Field Test Report Regarding MOD-026 - Verification of Models and Data for Generator Excitation System Functions and MOD-027 - Verification of Generator Unit Frequency Response (located in the Documents section of the WECC-0101 Team Site)that was conducted as part of the NERC 2007-2009 Generation Verification Project (covering MODs 26 and 27) conducted circa 2007. The Field Test notes in the background section that even in circa 2007, “approximately 80% of the [WECC] generators required to validate their data (generators larger than 10 MW) in WECC have met those requirements on a voluntary basis.”
Although a separate technical study to justify the BES threshold for purposes of this project was not conducted, the 10/20 MVA threshold contained in the GUMV Policy has been vetted and approved by the entire Planning Coordinating Committee (PCC – July 18-19, 2012). Since the PCC approved the threshold, and whereas the threshold has been in effect within WECC for multiple years, it is presumed that if the threshold were fallacious issues would have surfaced at the PCC. Further, since the DT is only proposing to match the threshold of the BES – not lower it to match the GUMV Policy, in light of the extensive vetting of the BES definition the DT believes the industry has already stated it threshold preference as approved by NERC/FERC.
Finally, since the existing approved thresholds were established by consensus – not a technical study - to include only an estimated 80% of Interconnection generation, by default this excludes 20% of all WECC generation. When coupled with FERC’s noted concern that generation at the 20 MVA level can have a significant impact on reliability (see Fn 7), the DT believes matching the variance threshold to the BES will meet FERC’s concerns while also including a portion of the heretofore excluded 20%.
Issue 4: Retain the ApplicabilityThreshold supported by the NERC Technical Studies
The commenter suggests that the existing thresholds should be left unchanged because the NERC drafting team for MOD-026-1 and MOD-027-1 established the applicability threshold based on technical studies whereas the WECC DT has failed to supply a technical study to justify the change.