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Scott Berry

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Indiana Municipal Power Agency

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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?


1) If not, please provide specific suggestions.


2) R3 through R7 add specificity and scope to the NERC PRC-006-1 standard requirements pertaining to identification and mitigation of islands as noted below.   

a. The Planning Coordinator needs to include additional items in their island identification criteria (R3).

b. The Planning Coordinator shall supply their island identification criteria (R4) and respond (R5) to any comments received on the island identification criteria from affected entities.

c. The Planning Coordinator shall identify and document islands by: applying the island identification criteria at least every 60 months (R6), supplying the results of applying the island identification criteria to affected entities (R6, Part 6.1), inviting, in writing, the participation of applicable entities, in the establishment of the mitigation plan (R6, Part 6.2) and establishing a mitigation plan to balance generation and Load and restore frequency in each area of islanding should the area of islanding become separated from the interconnection (R6, Part 6.3).

d. .Affected Distribution Providers, Transmission Owners and Generator Owners shall implement their portion of any mitigation plan (for the island(s)) as determined by the Planning Coordinator (R7).

Do you agree with the added specificity and scope pertaining to how islands are identified and addressed?


2) If not, please provide specific suggestions.


3) R8 and R9 extend the scope of the NERC PRC-006-1 standard to apply to Generator Owners’ underfrequency trip characteristics in planning UFLS programs as noted below. 

a. The premature tripping of a generating unit may have a very negative effect on the Bulk Electric System during a frequency excursion, and thus it is important to include a Generator Owner requirement within a standard dealing with UFLS. Generator Owners are required to either: 1) Set underfrequency protection in accordance with PRC-006-RFC-01 Attachment 1 (Time vs. Frequency curve) for generators that have automatic underfrequency protection installed, 2) establish and follow procedures for underfrequency operation in accordance with PRC-006-RFC-01 Attachment 1, for generators that do not have automatic underfrequency protection installed, or 3) arrange for Load shedding to be installed by mutual agreement with Distribution Providers, in addition to that required by the Planning Coordinator in Requirement R1 or Requirement R2, for generators that cannot meet the specifications in PRC-006-RFC-01 Attachment 1. (R8) (Note: the Time vs. Frequency curve in Attachment 1 is consistent with the curves in the NERC PRC-006-1 and draft PRC-024-1 standards (R11)).

b. Generator Owners (which are required to comply with R8) are required to supply underfrequency trip setting data to populate the Planning Coordinator’s UFLS data base (R9).  It is important for the Planning Coordinators to have such generator data in order to perform an accurate UFLS assessment (R10).  (This requirement may be removed once the NERC PRC-024-1 standard is completed and approved.)

Do you agree with the extended scope to include Generator Owners?


3) If not, please provide specific suggestions.

IMPA does not believe that Generator Owners should be in the regional standard for PRC-006-RFC-1.  The NERC PRC-006 standard removed Generator Owners from the standard due to PRC-024-1 being applicable to Generator Owners and being the generator ride-thru standard.  During an under frequency event, the generator will see a frequency decline and voltage will not remain the same or constant.  In addition, the frequency decline will be followed by a frequency over shoot (over frequency condition) in which relays must be set correctly or generators will trip off on an over frequency condition that was created by the initial under frequency event.  It is this over frequency condition in which some generators will not be able to adjust their over frequency relays in order to prevent damage to their unit (referencing the current PRC-024 curves).  In addition, the current draft copy of PRC-024 allows the generator trip within the "no trip zone" if the frequency rate of change is more than 2.5 Hz/sec which is needed protection against an Aurora event.  The current curve in PRC-006-RFC-1 is not complete since it does not give an upper limit and does not stipulate nominal conditions.  There needs to be a "no trip zone" and that is not shown completely or even labeled in PRC-006-RFC-1 Attachment 1.
In addition, the RFC UFLS draft standard does not consider that the generators might trip off line for other reasons besides an under freqency relay pickup.  Many generators will trip off line due to motors (heating issue with under frequency), controls (contacts dropping out or controls that are frequency sensative), or other plant limitations (gas turbines could possibly trip off due to fuel control issues caused by the frequency change) caused by under frequency event.  The NERC PRC-024 draft standard does consider this situation and has included it in its standards.
IMPA does not believe in making Generator Owner responsible for arranging Load shedding if it cannot set its under frequency protection relays to the proper curve set points due to possible damage to the unit during an under frequency event.  The Generator Owner will find it difficult to reach a mutual agreement with a Distribution Provider to load shed an equivalent amount of load to the Generator Owner's generation.  There is no incentive for the Distribution Provider to shed load and it may not even be enough to equal the Generator Owner's generation.  In today's marketplace Generator Owners are not necessarily connected in any way (physically or in business terms) to Distribution Providers.  Plus, trying to coordinate a load shedding scheme to know when and how much load is online is impossible.  If a Generator Owner cannot meet the settings due to possible damage to its generation unit and it cannot reach an agreement with a Distribution Provider, what choice is left for the Generator Owner to choose?  The Generator Owner does need an exception if it cannot set its underfrequency relays to the RFC UFLS standard requirements due to equipment limitations.
If a load shedding agreement is reached between a Generator Owner and a Distribution Provider, it will probably involve some form of financial compensation.  A regional or NERC standard should not force entities into some form of a financial compensation agreement.  It can create a market disadvantage for a generating entity and give advantages to other entities.  In addition, a reliability standard should not force a Generator Owner to choose between possible equipment damage and intentionally violating a reliability standard in order to generate power, if the Generator Owner cannot reach a load shedding agreement with a local Distribution Provider.

4) R10 and R11 extend the scope of NERC PRC-006-1 standard by including requirements to assess UFLS program implementation (in addition to UFLS program design required in the NERC PRC-006-1 standard) as noted below. 

a. The Planning Coordinator is to perform, document and make available an assessment of the effectiveness of the “implementation” of the UFLS programs.  The NERC PRC-006-1 standard only requires an assessment of the “design” of the UFLS programs.  This assessment will assess the effectiveness of the implemented UFLS programs using the information contained in the Planning Coordinator’s database which, while satisfying the design requirements, may exceed the design specifications (R10).

b. Applicable Distribution Providers, Transmission Owners and Generator Owners are to complete any required changes to the implementation of the UFLS program based on any implementation deficiencies noted in the Planning Coordinator’s assessment.  The NERC PRC-006-1 standard only requires the applicable entities to provide automatic tripping of Load in accordance with the UFLS program design and does not account for any changes which may be found necessary based on the Planning Coordinator’s assessment of implementation.  Such changes may be necessary for the overall effectiveness of the UFLS program when arresting frequency excursions.  The three calendar year completion interval was chosen to give applicable entities a reasonable amount of time for making changes in the field (R11).

Do you agree with the need to assess UFLS program implementation as well as design?


4) If not, please provide specific suggestions.

The Distribution Provider, Transmission Owner, and Generator Owner need a way of providing feedback on the Planning Coordinator's assessment, especially if there is an action or requirement in the implementation of the UFLS program that cannot be performed or met by a Distribution Provider, Transmission Owner, or Generator Owner.  Currently, requirement 10 (R10) requires the Planning Coordinator to establish an assessment of effectiveness of the implementation of the UFLS program and requirement 11 (R11) makes the Distribution Provider, Transmission Owner, and/or Generator Owner complete the required changes to the implementation of the UFLS program without giving any feedbak to the Planning Coordiantor (the NERC standard does not cover assessment of effectiveness).  Neither requirement addresses the issue if a Planning Coordinator is asking these entities to perform an action in an implementaton plan that violates an equipment limitation, equipment safety issue, or equipment's warranty.  The owners of the equipment need to have an input into the process and a say if the equipment is able to meet the requirements in the updated implementation of the UFLS program due to an assessment of effectiveness.

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


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

IMPA is answering no for the previous and below listed reasons
IMPA appreciates all the work the SDT has put into this standard and we realize at one time this regional standard may have been needed.  However, IMPA does not believe there is still a need for this standard for a few reasons.  First FERC has just released a NOPR indicating its intent to approve PRC-006-1.  The NOPR commenting period ends on November 21, 2011, and IMPA believes that FERC will take action on PRC-006-1 in the first quarter of 2012.  In addition, NERC is in the progress of completing PRC-024-1 which sets the requirements for the generator to ride through frequency and voltage excursions.  PRC-024-1 is the standard that fully covers the generators.  NERC has PRC-024-1 scheduled to be complete in the first quarter of 2012.  IMPA believes that only one standard is needed to ensure generators stay online during a frequency excursion and if two standards are applicable to generators in the RFC area, it will cause confusion and inefficiencies on the generator entities when trying to comply with two separate standards.  This also is true with PRC-006-1 and only needing one standard for entities to comply with the requirements.
The second reason is the RFC UFLS draft standard might proved guidance to the Planning Coordinators, but it may be too constraining to some Planning Coordinators who span more than just the RFC footprint.  Planning Coordinators should be able to write one UFLS program to cover their area.  If a Planning Coordinator's area covers three regions, it will probably have to write an UFLS program for each area in its applicable region in order to ensure compliance with each Regional UFLS program.  If the Planning Coordinators try to write one UFLS program to cover the NERC and three Regional standards, then conflicts may arise and it may make the UFLS program difficult to audit.  Planning Coordinators need flexibility and the NERC standard ensure coordination of UFLS programs among Planning Coordinators.
It is the belief of IMPA that the work on this regional standard should be halted.  It has been said many times that the standard drafting teams represent the industry.  If one looks back at the last commenting period, 15 of the 16 (there was one abstention) commenting entities believed that the standard was not ready for balloting, and 12 entities (including PJM and MISO) stated that they believed that the work of the RFC UFLS standard development should be suspended in lieu of the NERC PRC-006-1 standard development.  As for covering reliability, we believe that the two NERC standards (PRC-006-1 and PRC-024-1) should be allowed to be implemented and then determine if any reliability gaps exist in the UFLS program.  This includes allowing these two NERC standards to replace the old legacy UFLS documents.  One also needs to remember that we are not creating an UFLS program from scratch and that there is UFLS protection even today.
If the work continues on the UFLS standard the applicability section needs to be corrected to reflect the same applicability section as NERC PRC-006-1.  The addition of "UFLS entities" consistent with NERC PRC-006-1, with Transmission Owners and Distribution Providers listed under it, needs to be added under the applicability section.  This will also require using "UFLS entities" throughout the standard instead of Distribution Providers in most cases.

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