FERC approves revised reliability standard proposed by NERC for reclosing relays
FERC directs that NERC develop a modification to the reliability standard to include maintenance and testing of supervisory relays
FERC on Jan. 22 approved, under the Federal Power Act, a revised reliability standard, PRC-005-3 – Protection System and Automatic Reclosing Maintenance – submitted by NERC.
FERC said in its order that it also approves one new definition and six revised definitions referenced in the reliability standard, the assigned violation risk factors and violation severity levels, as well as NERC’s implementation plan, according to GenerationHub.
Consistent with Order No. 758, the reliability standard requires applicable entities to test and maintain certain autoreclosing relays as part of a protection system maintenance program. However, FERC added, to ensure that proper maintenance and testing is done for all parts of a reclosing relay scheme that can affect the reliable operation of the bulk power system, FERC directs that NERC develop a modification to the reliability standard to include maintenance and testing of supervisory relays.
NERC on Jan. 22 said that it is pleased with the action taken by FERC at its Jan. 22 open meeting to approve the standard, which promotes reliability by ensuring that certain reclosing relays are subject to the standard’s mandatory maintenance requirements.
Noting that FERC directed NERC to modify the standard to include supervisory relays associated with applicable reclosing relay schemes, NERC said that it will respond to FERC’s directive and appreciates FERC’s approval of the standard.
According to FERC’s order, NERC, in its February 2014 petition seeking approval of PRC-005-3, said that reclosing relays are used “on transmission systems to restore elements to service following automatic circuit breaker tripping” and are “typically installed to lessen the burden on transmission operators of manually restoring transmission lines.”
NERC also said that “while more efficient restoration of transmission lines following temporary faults does provide an inherent reliability benefit, certain applications of reclosing relays can result in undesired relay operation or operation not consistent with relay design, leading to adverse reliability impacts.”
FERC noted that in 2007, in Order No. 693, it approved an initial set of reliability standards that NERC submitted, including initial versions of four protection system and load-shedding-related maintenance standards, including PRC-005-1.
Additionally, FERC directed that NERC develop a revision to PRC-005-1 to incorporate a maximum time interval during which to conduct maintenance and testing of protection systems, and to consider combining into one standard the various maintenance and testing requirements for all of the maintenance and testing-related reliability standards for protection systems, underfrequency load shedding (UFLS) equipment and undervoltage load shedding (UVLS) equipment.
In February 2012, FERC issued Order No. 758 accepting NERC’s proposed interpretation of PRC-005-1, which identified the types of protection system equipment to which the reliability standard applied. Additionally, FERC directed NERC to develop modifications to the standard to address gaps highlighted by the proposed interpretation, including the need to address reclosing relays that may affect bulk power system reliability.
FERC also said that in its February 2014 petition, NERC maintained that PRC-005-3 promotes reliability by making certain reclosing relays subject to a mandatory maintenance program, including adding detailed tables of minimum maintenance activities and maximum maintenance intervals for the reclosing relays.
NERC said that the purpose of the standard is to “document and implement programs for the maintenance of all protection systems and automatic reclosing affecting the reliability of the bulk electric system so that they are kept in working order.”
FERC noted that NERC also proposed to include a new definition as part of the revised standard. Automatic reclosing includes reclosing relay and control circuitry associated with the reclosing relay.
Additionally, NERC proposed modifications to four defined terms referenced in PRC-005-2, protection system maintenance plan, component type, component, and countable event, to reflect the inclusion of automatic reclosing components.
Prior to issuance of Order No. 758, NERC had begun developing revisions to its initial maintenance standards for protection systems and underfrequency and undervoltage load shedding equipment in response to the Order No. 693 directives. FERC added that it approved those revisions, reflected in the consolidated reliability standard, PRC-005-2, in December 2013 in Order No. 793.
NERC’s implementation plan for PRC-005-3 incorporates the phased-in implementation period approved for PRC-005-2 with the addition of compliance dates for the new requirements for automatic reclosing components. PRC-005-2 will be retired in the United States immediately before the effective date of PRC-005-3, on the first day of the first calendar quarter 12 months following regulatory approval.
According to NERC, FERC added, applicable entities will continue to calculate compliance dates for protection system components by counting forward from the FERC approval date of PRC-005-2, and for automatic reclosing components by counting forward from the effective date of FERC approval of PRC-005-3. Also, for newly identified automatic reclosing components – for instance, resulting from the addition or retirement of generating units – compliance would be required by the end of the third calendar year following identification of those components.
FERC also noted that it issued last July a notice of proposed rulemaking (NOPR) proposing to approve PRC-005-3, and stating that it had “concerns whether the thresholds are too narrow.”
Based on those concerns, FERC proposed to require NERC to submit a report examining the effectiveness of the revised standard in identifying reclosing relay schemes that could affect the reliable operation of the bulk power system based on actual operations data and simulated system conditions from planning assessments.
The NOPR proposed, for instance, that NERC enhance the granularity of its existing misoperations database “to gather relevant information regarding events that involve autoreclosing relays, such as distance from the fault, whether the relay reclosed into the fault, and whether that reclosure caused or exacerbated an event.”
Among those commenting on the NOPR were NERC, the Edison Electric Institute and IDACORP’s Idaho Power.
FERC noted that it adopts its NOPR proposal and approves PRC-005-3 “as just, reasonable, not unduly discriminatory or preferential and in the public interest.”
It also said that it directs NERC to develop one modification to the reliability standard pertaining to the inclusion of supervisory relays for applicable reclosing relay schemes.
FERC noted that there are an estimated 23 generating plants in PJM Interconnection that meet the inclusion criteria of the proposed standard, representing about 47,000 MW of the about 184,000 MW within PJM. Based on 2012 data, total installed capacity in the continental U.S. is about 1.2 million MW, FERC said, adding that applying the PJM ratio to that total results in an estimated 144 plant sites nationwide to which PRC-005-3 would be applicable.
FERC said it also assumes that a substation will be located within 10 miles of each plant site, resulting in an estimated total number of entities that meet the inclusion criteria of 288. Furthermore, FERC said it assumes that all generator owners and transmission owners must review their existing plant and substation sites to determine applicability under the proposed standard.
Affected entities must do a one-time review of their existing reclosing scheme maintenance program to ensure that it contains at a minimum certain activities listed in PRC-005-3, and that the activities are done within a certain applicable maximum interval. If the existing reclosing scheme maintenance program does not meet the criteria in the reliability standard, the entity will have to make certain adjustments to the program, FERC added.
Among other things, FERC said that the final rule is effective 60 days after publication in the Federal Register.