GWG Conference Call held 2/5/10

Attendees:

Mitch Williams, Jim Fehr, Blake Mertens, Mike Sheriff, Andrew Lachowsky, Kevin Goolsby, and Scott Jordan

SPP Compliance feedback for sections of the SPP Criteria that the GWG has influence over and are in need of clarification on added verbiage for compliance issues. This feedback is a result of recent regulatory audits and the scrutiny that the oversight groups have had concerning the wording of documents used as proof of being compliant.

The group discussed the feedback concerning Sections 7 and 12 fo the SPP Criteria. The high level discussion will follow the proposed section edits in the form of bullet points.

7.8.4 Generator Performance during Temporary Excursions

7.8.4.1 Excursions in Frequency and Voltage

Generators shall be able to sustain temporary excursions in under frequency, over frequency, under voltage, and overvoltage conditions. The protective relay systems regarding these conditions shall be coordinated with SPP system under frequency and under voltage load shedding schemes. SPP’s under frequency load shedding plan allows for three stages of load shed at frequencies of 59.3, 59.0, and 58.7 Hz. The members shall shed 10% of their load at each stage in an effort to stop the decline in frequency. Control Areas may elect to implement a fourth stage at 58.5 Hz which can call for the opening of tie-lines, removal of generating units from buses, additional steps of load shedding, or the breakup of the transmission system into predetermined islands with balanced amounts of generation and load in each island. Due to the structure of the under frequency load shedding plan, it is necessary that generators be able to sustain frequencies to at least 58.5 Hz so that the load shedding plan works as designed. Any generator that must trip off line prior to system frequency declining to 58.5 Hz must have a block of load equal to the generator’s output capability tripped at the same frequency as the generating unit.

In the absence of a regional or control area under voltage load shedding plan, generators shall be able to sustain non-interruptible operation at voltages between 92%90%[M.J.1] and 105% of the nominal transmission voltage at the generator bus. During Emergency and/or transient system conditions, all reasonable measures should be taken to avoid tripping of the generator due to high or low voltage.

  • Kevin Goolsby will also seek input from the SPCWG on this section.
  • Remove verbiage concerning voltage in the first sentence of the first paragraph and the reference in the first sentence of the second paragraph.
  • Align the voltage bandwidth with either Section 3.3 of the criteria or look at any reference in the Generator Interconnect Process documentation.

12.0 ELECTRICAL FACILITY RATINGS

  • Generator section does not state that the most limiting element will be the rating like it does in the transmission section.
  • Generator Capability testing needs a clearer statement about being a way to rate generation or not. Does SPP want to use capability test to rate the units and use these ratings in the models?
  • 12.2.10.2 States relay settings are to be considered in the ratings. We need to make sure that generation also has a statement concerning relays settings and their review for rating of the equipment.

12.1 Rating of Generating Equipment

To provide a basis for comparing operating margin of various entities and to assure reasonable distribution of the margin, generating equipment shall be uniformly and consistently rated topermit accurate planning. Procedures are herein established for rating generating units andestablishing a system of records so that changes in capacity during the life of the equipmentcan be recognized. These procedures define the framework under which the ratings are to beestablished while recognizing the necessity of exercising judgment in their determination. Theterms defined and the ratings established pursuant to these procedures shall be used for SPPpurposes, including determining capacity margins for both planning and operating purposes,scheduling maintenance, and preparation of reports of other information for industryorganizations, news media, and governmental agencies. These ratings are not intended torestrict daily operating practices associated with SPP operating reserve sharing, for which moredynamic ratings may be necessary. Each member shall test its generating equipment inaccordance with the procedures contained herein. On the basis of these tests summer andwinter net capability ratings for each generating unit and station on the member's electricsystem shall be established. This net capability is referenced in many NERC documents as netdependable capacity that is the maximum capacity a unit can sustain over a specified periodmodified for seasonal limitations and reduced by the capacity required for station service orauxiliaries. The summer net capability of each unit may be used as the winter net capabilitywithout further testing, at the option of the member. As a minimum, each member shall conducttests on all its generating equipment which is designated as a part of the resource for supplyingits own peak load and minimum capacity margin requirement of these Criteria. The seasonal netcapabilities, gross capabilities, and auxiliary loads shall be furnished to SPP for all existinggenerating units and upon installation of new generating units and shall be revised at othertimes when necessary. The net generating limits will be equal to or less than the most limiting major electrical component including but not limited to bus, breakers, switches, transformers, or generating protection relays. Members shall annually report the seasonal net generating unitcapability in conjunction with the Department of Energy 411 Report data gathering effort and insure that the generator limits are used in determining the data contained in MDWG power flow models . Duringthe capability test the net capability shall be reported. Additionally, the unit’s gross capabilityand auxiliary load shall be reported. The gross capability and auxiliary load shall be determinedfrom the test or using such methods as use of manufacturer data, commissioning data,performance tracking, etc. Data used to determine net capability shall be obtained from testing.

  • Discussed that the feedback form the oversight groups was inferring the generation components are being treated like transmission system components.
  • Ensure that the major electrical components are referenced and not the individual systems of the generator itself that are test during the capability testing.
  • Add verbiage to section 12.1. This is already a lengthy section but it is felt that this is the best place to insert the needed verbiage.
  • Try to incorporate all of the oversight groups feedback in this section.

[M.J.1]This aligns the voltage bandwidth to section 3.3