This comment form is no longer interactive because the comment period is closed.

WECC - Regional Reliability Standard | VAR-501-WECC-3

Description:

Start Date: 12/12/2016
End Date: 01/25/2017

Associated Ballots:

Ballot Name Project Standard Pool Open Pool Close Voting Start Voting End

Filter:

Hot Answers

Southern Company, Segment(s) 1, 3, 5, 6, 8/3/2016

- 0 - 0

Lynda Kupfer, On Behalf of: Lynda Kupfer, , Segments 1, 3, 5

- 0 - 0

Other Answers

Laura Nelson, On Behalf of: Laura Nelson, , Segments 1

- 0 - 0

Bishnu Sapkota, On Behalf of: GE - GE Power Systems Energy Consulting, WECC, Segments 10

- 0 - 0

Richard Jackson, On Behalf of: U.S. Bureau of Reclamation, , Segments 1, 5

- 0 - 0

Hot Answers

Southern Company, Segment(s) 1, 3, 5, 6, 8/3/2016

- 0 - 0

Lynda Kupfer, On Behalf of: Lynda Kupfer, , Segments 1, 3, 5

- 0 - 0

Other Answers

Laura Nelson, On Behalf of: Laura Nelson, , Segments 1

- 0 - 0

We have reviewed the proposed standard VAR-501-WECC-3, Power System Stabilizers.  In general, the document looks good, however, we see a need for adjustment on the requirement R3 of the document. 

The requirement R3 states that the final PSS gain should be between 1/3 (10 dB) to 1/2 (6 dB) of the maximum practical gain that could be achieved during PSS commissioning.  The maximum practical gain may also be associated with the interactions of the PSS with low-order torsional modes of the turbine-generator unit which may or may not be evaluated during the PSS commissioning test.  Accordingly, the PSS gain may need to be kept lower than 1/3 of the maximum practical gain that can be proved during the testing.  The reason for this recommendation is to avoid any potential detrimental issues associated with the above-mentioned torsional interactions.  So, we would recommend to make adjustment in the statement as follows:

 

The final PSS gain should not be greater than 1/3 of the maximum practical gain.

Bishnu Sapkota, On Behalf of: GE - GE Power Systems Energy Consulting, WECC, Segments 10

- 0 - 0

Richard Jackson, On Behalf of: U.S. Bureau of Reclamation, , Segments 1, 5

- 0 - 0

Hot Answers

  1. Redline, page 14, Section Requirement R3, first sentence:  What is RRS?  Should RSS be RRS (regional reliability standard)?
  2. With regard to the draft standard section R3.3:    PSS Gain shall be set to between 1/3 and 1/2 of maximum practical gain.

    The SDT should define “maximum practical gain”.  Is this meant to be the gain value resulting in the threshold of instability?  In defining the maximum practical gain, one must account for older PSS systems and the newer dual input PSS units using the integral of accelerating power which are stable at significantly higher gains.

Southern Company, Segment(s) 1, 3, 5, 6, 8/3/2016

- 0 - 0

Comment:

Please clarify the conditions and timing under which an automatic voltage regulator without PSS, or a PSS that cannot meet the tuning requirements in R3 would have to be replaced. 

Our interpretation for R4 is that only if we were replacing the voltage regulator on an existing exciter would we have to add PSS to a unit that doesn’t currently have it.  

R3.5 provides an exemption for PSS that cannot be tuned but R5 requires repair or replacement within 24 months of determining it cannot be tuned to the standard requirements.  Because R3 is effective 5 years after approval for existing systems, would we then have 2 years after that to replace PSS that cannot be tuned to the specifications? 

Lynda Kupfer, On Behalf of: Lynda Kupfer, , Segments 1, 3, 5

- 0 - 0

Other Answers

Laura Nelson, On Behalf of: Laura Nelson, , Segments 1

- 0 - 0

Please refer to the comment for question 2.

Bishnu Sapkota, On Behalf of: GE - GE Power Systems Energy Consulting, WECC, Segments 10

- 0 - 0

Richard Jackson, On Behalf of: U.S. Bureau of Reclamation, , Segments 1, 5

- 0 - 0

Hot Answers

 

 

Southern Company, Segment(s) 1, 3, 5, 6, 8/3/2016

- 0 - 0

Lynda Kupfer, On Behalf of: Lynda Kupfer, , Segments 1, 3, 5

- 0 - 0

Other Answers

Laura Nelson, On Behalf of: Laura Nelson, , Segments 1

- 0 - 0

Bishnu Sapkota, On Behalf of: GE - GE Power Systems Energy Consulting, WECC, Segments 10

- 0 - 0

In general, Reclamation supports the changes proposed in VAR-501-WECC-3. Reclamation requests that the standard be revised to contain clarifying language regarding the allowance for a PSS to be out of service in R2: Is a PSS outage of 30 minutes considered a violation or not? During what interval is “more than 30 minutes” considered a violation – per occurrence, or a total per year?

 

Reclamation suggests that R3 be clarified to state that each Generator Owner shall tune its PSS to meet “ALL” the following criteria (3.1 “and” 3.2 “and” 3.3 “and” 3.4 “OR” 3.5) in order to better align with the VSL for R3 which indicates a violation if ANY of the criteria are not met.

 

R4 by itself can be misinterpreted to mandate installation of PSS on existing generators.  To avoid confusion, BOR recommends copying the text of the "Mandate to Install a PSS" section (on page 8 of the Clean version) to a third bullet under R4. 

 

R5 may be overly restrictive given procurement issues that entities, especially federal agencies, could experience. The clause “or a plan to repair or replace not to exceed 36 months” should be included to offset the possibility of unforeseen delays that could cause a possible violation beyond the entity's control.

 

In the Evidence Retention section, it is unclear what the phrase "plus calendar current" means

Richard Jackson, On Behalf of: U.S. Bureau of Reclamation, , Segments 1, 5

- 0 - 0

Hot Answers

Southern Company, Segment(s) 1, 3, 5, 6, 8/3/2016

- 0 - 0

Lynda Kupfer, On Behalf of: Lynda Kupfer, , Segments 1, 3, 5

- 0 - 0

Other Answers

Laura Nelson, On Behalf of: Laura Nelson, , Segments 1

- 0 - 0

Bishnu Sapkota, On Behalf of: GE - GE Power Systems Energy Consulting, WECC, Segments 10

- 0 - 0

Richard Jackson, On Behalf of: U.S. Bureau of Reclamation, , Segments 1, 5

- 0 - 0