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WECC – 0070 Governor Droop Criterion First Team Meeting Background

WECC – 0070 Governor Droop Criterion First Team Meeting Background. WECC – 0070 First Team Meeting. Purpose What are we addressing? No NERC Standard MORC Section 1.C.2 . WECC – 0070 First Team Meeting. Purpose

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WECC – 0070 Governor Droop Criterion First Team Meeting Background

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  1. WECC – 0070Governor Droop CriterionFirst Team Meeting Background

  2. WECC – 0070 First Team Meeting • Purpose • What are we addressing? • No NERC Standard • MORC Section 1.C.2

  3. WECC – 0070 First Team Meeting • Purpose A. Current MORC contains a criterion requiring governors to be set at a 5% droop. With the proposed retirement of existing MORC, a new governor droop criterion needs to be developed or similar droop criterion to MORC Section 1.C.2 needs to be retained.  Currently MORC Section 1.C.2 requires that governor droop shall be set at 5% to provide an equitable and coordinated system response to load/generation imbalances.  It may be more appropriate to develop governor droop criteria that require: 1. An effective governor droop response for an area (e.g. 10% or some other percentage), 2. A criteria that permits a range of governor droop settings (e.g. from 4% to 5%), 3. A combination area droop response and generator setting range. 

  4. WECC – 0070 First Team Meeting

  5. WECC – 0070 First Team Meeting Current Criteria MORC 1.C.2: 2.Governors. To provide an equitable and coordinated system response to load/generation imbalances, governor droop shall be set at 5%. Governors shall not be operated with excessive deadbands, and governors shall not be blocked unless required by regulatory mandates.

  6. WECC – 0070 First Team Meeting • The goal of the criterion development would be to develop a governor droop or control criterion that is more technically based and enhances system reliability. •  The objective is to develop a regional criterion as a replacement to current MORC Section 1.C.2. The ORCWG recommends that a criterion be developed to address governor droop settings.  The drafting team should develop a governor droop criteria that contain a range for droop settings and/or if appropriate an area (system) droop performance requirement.

  7. WECC – 0070 First Team Meeting • On February 3, 2010 the Standards Request Routing Committee (SRRC) met via telephone to discuss assignment of WECC-0070, Governor Droop Criterion.  The SRRC concluded the Request was in scope and assigned drafting to the OC.  Mr. Hulls, chair of the OC, assigned the drafting task to the Operating Reliability Criteria Work Groupwith augmentation to be sought from individuals with experience in generator controls. 

  8. WECC – 0070 First Team Meeting • Comments received during the 30 day Criterion request comment period – abridged-

  9. WECC – 0070 Standard Request Comments • Fred Le Blanc, Burbank Water and Power • The criterion should specify a minimum droop setting for governors.  I would propose the minimum to be 5% droop.  There are valid reasons (especially with combined cycle units) that one would want to have a 4% or better droop setting. • Establishing an Interconnection wide performance of say 10 percent might be problematic if we do not meet that.  We need to use caution if we do this.

  10. WECC – 0070 Standard Request Comments • Want a policy that addresses the unique characteristics of different types of governors and plants. • Pelton type turbines have essentially two governors.  • The deflector governor operates on a 5% speed droop.  • The needles governor controls water flow and maintains a constant flow regardless of speed.  Speed regulation is physically not possible due to 8 mile long penstock with 1000 ft of head.  • The current policy of "set droop to 5%" doesn't seem to adequately address the different types of turbines and plants.

  11. WECC – 0070 Standard Request Comments • Baj Agrawal, APS • The scope looks good however, the drafting committee should be allowed to change it if needed.

  12. WECC – 0070 Standard Request Comments • Mark Thompson, Kevin Wiens, AESO • The drafting team should consider what “success” would look like when considering governor droop (e.g., is success based on the setting or value of droop in the governor system, or is it the MW performance from the droop setting, or is it related to the performance of the Balancing Area. • The considerations also need to examine system operation and governor droop from wide range of possible operating conditions including system restoration, system normal, etc. • Considerations to allow droop settings be changed to accommodate specific operating conditions such as under black start.

  13. WECC – 0070 Standard Request Comments • Mark Thompson, Kevin Wiens, AESO • Ensure that this standard will not conflict with other requirements and consider how this could enhance other requirements. • Droop needs to be clearly defined – is it a characteristic of performance or is a setting? Suggested things to consider are the  basis on how droop would be measured and/or set. (.i.e. MW capability, MVA, Nameplate, valve) • Suggest considerations for other generator technologies, eg: • Wind generation • Photovoltaic • Batteries • Consideration that droop could be adaptive or could be intentionally non-linear such as in blackstart.

  14. WECC – 0070 Standard Request Comments • Koehn, BPA • AGC supports a more detailed look into changing the existing droop settings.  Although a required droop characteristic is a decent goal, we have seen over the past decades that it is not sufficient to insure an adequate response to frequency deviations.   Our preference is that they go back and recreate the frequency response SAR and go forth with a standard, but if this is not possible, the 5% should be maintained with the allowance that it can be set between 4 and 6 % droop response.    

  15. WECC – 0070 Standard Request Comments • Koehn, BPA • This was discussed quite a bit at the NERC Resources Subcommittee a few years ago and they came to the conclusion that while it is perfect if all governors are set with a 5% droop, it is not unreliable to have a range of settings with a maximum deviation of +/- 2%.  Having the ability to set the droop response to between 4% and 6% would achieve this goal and still maintain system reliability.

  16. WECC – 0070 Standard Request Comments • Eleanor Ewry, PSE • PSE would like the criterion to more fully address the subject of non-responsive units running on thermal limits or load control.

  17. WECC – 0070 Standard Request Comments • PPL Energy Plus • The “Detailed Description” on the WECC website states the existing 5% droop fails to provide balanced governor response. • Please provide statistically significant supporting documentation from actual events for this statement? • Please provide statistically significant proof that this compromises grid reliability? • How does the drafting team advocating a non-uniform droop criterion in the west plan to coordinate the criterion with any plans the WECC has to implement a Frequency Responsive Reserves (FRR) requirement? • Please explain the relationship between the two programs.

  18. WECC – 0070 Standard Request Comments • PPL Energy Plus • Does the drafting team recognize: • That lower droop will create more wear and tear on equipment and has other cost-related implications?  • That assigning droop other than a uniform value (i.e. 5%) has cost allocation /cross-subsidization implications?

  19. WECC – 0070 Standard Request Comments • PPL Energy Plus • How does the drafting team plan: • To avoid creating an atmosphere where certain generators are assigned lower droop (such as hydro/thermal) and others (such as wind and solar) are allowed higher droops? • To account for the fact that many older machines may not be able to physically have a droop other than 5% or could be limited to 5% maximum or minimum?

  20. WECC – 0070 Standard Request Comments • PPL Energy Plus • Since lower droop leads to more oscillatory behavior by machines, has the drafting team coordinated droops of less than 5% with the various oscillatory modes in the WECC, modes that are not captured in the PSS/E and PSLF models? • Who will be responsible to assign droop to specific machines if the droop is no longer uniformly 5%?  • How does the drafting team plan to guard against a balancing authority, possibly with affiliated generation, assigning lower droops to non-affiliates?

  21. WECC – 0070 Standard Request Comments • PPL Energy Plus • Does “technically-based” criterion mean the criterion is based on the two models (PSLF and PSS/E) used in the WECC? Would the drafting team please provide a statistical analysis of the error in how the models described governor performance during disturbances vs. how plant governors actually performed? • If a “technically-based” criterion means a study-based methodology is adopted for assigning droop: • How do you address concerns that many generator owners have that computer models fail to capture the nuances of machines and their governors and that abandoning a uniform 5% in favor of assigning droop based on computer models (which are full of assumptions) could actually result a decrease in grid reliability? • Do you anticipate large amounts of time spent by study engineers needed to establish a study-based methodology or criterion for assigning droop and then actually assigning the droop in an economically just way?

  22. WECC – 0070 Standard Request Comments • PPL Energy Plus • Would you please detail the pro’s and con’s of developing a study-based method for assigning droop vs. a fair, simple method that treats all generators the same? • If you proposes to move away from a uniform (i.e. 5%) droop, does the drafting team plan to have the Reliability Coordinators involved in assigning droop to avoid discrimination? • What if different seasons or times of day required different droops: does the drafting team anticipate an hourly or daily “droop schedule”?

  23. WECC – 0070 Standard Request CommentsPPL Energy Plus • The idea behind a uniform droop setting is to get all generators to respond similarly to frequency changes and thus restore grid frequency. Since generator owners may want to tune their units or plants to optimize droop settings, would the drafting team investigate allowing generator owners the following options? • Droop by plant vs. droop by unit. • Droop by fleet vs. droop by plant. • There are generation-only balancing authorities and possibly wind generation-only BAs. • How would the WECC assign droop to generation-only BAs?  • Is the technology available for wind-only or solar-only BA’s to provide droop? If not, where would this droop come from?

  24. WECC – 0070 Standard Request CommentsPPL Energy Plus • Would the drafting team explain the unique situation in the WECC that requires a different criterion than the rest of the nation? • It appears that the drafting team anticipates increased transfer capabilities on many tie-lines as a result of non-uniform governor droop settings. Has the drafting team calculated the benefit-cost ratio of implementing a generator-based non-uniform governor droop setting approach versus using non-generator based methods to achieve the same increase in transfer capability?

  25. WECC – 0070 Standard Request CommentsPPL Energy Plus • Does the drafting team anticipate that with new governor settings in the WECC, all WECC path ratings might need to be re-established? Assuming this true: • Would the drafting team prioritize which paths to re-rate first? • Does the drafting team believe that the existing path rating would stay in-place until the new studies are complete? • Does the drafting team anticipate some path ratings will increase and some will decrease with new governor droop settings and if so, how does the WECC plan to make transmission owners and generators who lose capacity or the ability to sell their output economically whole?

  26. WECC – 0070 Team Meeting

  27. WECC – 0070 Team Meeting • Timeline? • How to get to conclusion? • What studies need to be conducted? • Propose Sub-team? • Next Meetings?

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