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David Thorne

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Potomac Electric Power Company

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Alvin Depew
Carl Kinsley

1) Subsequent to a review performed by NERC staff, the SDT has reformatted and modified certain requirements of the draft PRC-006-RFC-01 standard. Do you agree with the reformatted structure and modified requirements of the standard?

No

1) If not, please provide specific suggestions.

No.  It does not appear that this draft lines up with all requirements with NERC PRC-006-1.  This RFC standard should be reviewed and modified to be consistent with and conform to all the applicable requirements of NERC PRC-006-1.
Some inconsistencies are described below:
1)  NERC Standard PRC-006-1 establishes nationwide performance criteria for UFLS schemes, including frequency versus time plots, which prescribe limits (both over and under frequency) within which the simulated system frequency response must remain.   Adherence to this performance criterion should be mentioned in the RFC standard.   
2)  NERC PRC-006-1 standard provides a frequency versus time threshold for generator over/under frequency tripping, within which individual generator frequency tripping must be modeled.   It appears that the generator underfrequency tripping criteria outlined in Requirement R12 of the RFC standard falls inside these NERC threshold boundaries, requiring detailed modeling of all generators.   In addition, this RFC standard does not establish any criterion for overfrequency tripping of generators, or for the collection of overfrequency trip points, which would be necessary to satisfy the modeling and performance criteria established by NERC PRC-006-1.   Over/under frequency generator tripping criteria should be established in the RFC standard consistent with NERC PRC-006-1 and PRC-024-1.
3) NERC PRC-006-1 imposes V/Hz limits as part of the UVLS performance criteria.  There is no mention of V/Hz criteria in the RFC standard.
4)  V4 of Draft 6 of PRC-006-RFC-01 removed all applicability qualifiers from paragraph 4.3 Generator Owners.   Without some form of applicability qualifier it is unclear what generator facilities are in scope for this standard.  As such, one might mistakenly conclude that it applies to small units not connected to the BES.  This standard should be consistent with NERC PRC-006-1, which limits generator applicability to the following:
• any facility consisting of one or more units connected to the BES at a common bus with total generation above 75 MVA (gross nameplate rating)
• individual generating units greater than 20 MVA (gross nameplate rating) directly connected to the BES
• generating plants/facilities greater than 75 MVA (gross aggregate nameplate rating) directly connected to the BES

2) Time Horizons have been added to the Requirements. Do you agree that the Time Horizons are appropriate for the requirements?

Yes

2) If not, please provide specific suggestions.

 

3) The Measures have been modified to include more examples on how to assess performance and outcomes for the purpose of determining compliance with the requirements.  Do you agree that the Measures are appropriate?

No

3) If not, please provide specific suggestions.

The term “BES” should precede the phrase “capacitor banks” in Measurement M3 to be consistent with previous drafts of the standard and with Requirement 14.7, which requires overvoltage tripping data only on capacitor banks connected to the BES.    R3 and R16.2 should also use BES preceding capacitor banks.  The intent of these requirements and measures is to ensure adequate control of overvoltages on the BES following an UFLS event and should not be applicable to capacitor banks installed on lower voltage distribution facilities.

4) The Violation Severity Levels (VSLs) have been modified to be consistent with the modified requirements and based on NERC and the FERC guidelines.  Do you agree that the VSLs are appropriate?

Yes

4) If not, please provide specific suggestions.

 

5) The Violation Risk Factors (VRFs) have been modified to be consistent with the modified requirements and based on NERC and the FERC guidelines.  Do you agree that the VRFs are appropriate?

Yes

5) If not, please provide specific suggestions.

 

6) The Standard Drafting Team believes the standard is ready for Category Ballot.  Do you agree?

No

6) If not, please provide specific suggestions that would make it acceptable to you.

See responses above

Created at 9/7/2012 10:09 AM by System Account
Last modified at 9/7/2012 10:09 AM by System Account