Transmission Relay Loadability Reliability Standard, 091511 FERC, RM08-13-004

Docket Nº:RM08-13-004
Party Name:Transmission Relay Loadability Reliability Standard
Judge Panel:Before Commissioners: Jon Wellinghoff, Chairman; Marc Spitzer, Philip D. Moeller, John R. Norris, and Cheryl A. LaFleur. Nathaniel J. Davis, Sr., Deputy Secretary.
Case Date:September 15, 2011
Court:Federal Energy Regulatory Commission

136 FERC ¶ 61, 185

Transmission Relay Loadability Reliability Standard

No. RM08-13-004

United States of America, Federal Energy Regulatory Commission

September 15, 2011


Before Commissioners: Jon Wellinghoff, Chairman; Marc Spitzer, Philip D. Moeller, John R. Norris, and Cheryl A. LaFleur.


1. In this order, the Commission addresses requests for clarification or reconsideration of Order No. 733-A, which addressed requests for rehearing and clarification of our Final Rule on the North American Electric Reliability Corporation’s (NERC) Reliability Standard PRC-023-1 regarding “relay loadability.”1 The petitioners seek further clarification of several matters that were clarified in Order No. 733-A. We address these requests substantively and, in part, grant clarification and, in part, deny requests for clarification.

2. In addition, the petitioners seek clarification or reconsideration regarding certain issues arising from the Final Rule, Order No. 733 that should have been raised at an earlier stage of this proceeding, on rehearing. These arguments are rejected as untimely requests for rehearing of Order No. 733. The petitioners also seek to augment the record by submitting expert affidavits and request that the Commission clarify or reconsider Order No. 733-A in light of the supplemented record. As discussed below, we reject the attempt to expand the record at this late stage of the proceeding. While we reject the untimely arguments and affidavits on procedural grounds, we nonetheless review these matters in a summary manner and deny the requests on substantive grounds.

I. Background

3. On March 18, 2010, the Commission issued Order No. 733, which approved Reliability Standard PRC-023-1 (Transmission Relay Loadability) submitted to the Commission by NERC, the Commission-certified Electric Reliability Organization (ERO) for the United States. The Reliability Standard requires transmission owners, generator owners, and distribution providers to set load-responsive phase protection relays2 according to specific criteria in order to ensure that the relays reliably detect and protect the electric network from all fault conditions but do not limit transmission loadability3 or inhibit system operators’ ability to protect system reliability. Pursuant to section 215(d)(5) of the Federal Power Act (FPA), 4 the Commission directed the ERO to develop certain modifications to PRC-023-1 and to develop a new Reliability Standard that requires the use of protective relay systems that can differentiate between faults and stable power swings and, when necessary, phase-out relays that cannot meet this requirement.

4. On February 17, 2011, the Commission issued Order No. 733-A providing clarifications and granting rehearing, in part, and denying rehearing, in part. Among other matters addressed in the order, the Commission clarified its directives to modify PRC-023-1 to include a mandatory test for planning coordinators to use to identify which facilities below 200 kV are critical to the reliability of the bulk electric system (and therefore subject to the Standard) and to revise Attachment A to make the Standard applicable to supervisory relays. Additionally, the Commission clarified a directive requiring NERC to develop a new Reliability Standard addressing stable power swings by requiring the use of protective relays that can differentiate between faults and stable power swings and, when necessary, phase-out relays that cannot meet this requirement. The Commission also offered clarification regarding the applicability of the Standard to backup protective relays located at a generator step-up transformer.

5. In addition, Order No. 733-A articulated the structure established by section 215 of the FPA by which the Commission, and not solely the ERO, has the responsibility and authority to identify reliability gaps. The ERO is authorized to address reliability matters through its Reliability Standards development process, and the Commission through its review of proposed Reliability Standards and authority to direct modifications or new Standards that address specific issues necessary to carry out the purposes of section 215.

II. Request for Clarification of Reconsideration

6. On March 21, 2011, the Edison Electric Institute and the National Rural Electric Cooperative Association (collectively, EEI/NRECA) jointly filed a timely motion and the American Public Power Association and the Transmission Access Policy Study Group (collectively, APPA/TAPS) together filed a motion, in both instances, requesting clarification or reconsideration of Order No. 733-A.5

7. In general, both motions assert the Commission based its directives on a faulty understanding of the Blackout Report6 or an incorrect characterization of relay engineering. Both motions also reprise issues addressed in Order No. 733-A relating to the Commission exceeding its statutory authority by failing to give “due weight” to the technical expertise of the ERO and by giving overly prescriptive directives. Finally, EEI/NRECA seek clarification or reconsideration of language that they characterize as suggesting that the Commission expects 100 percent relay security and of the Commission’s directive regarding generator relays.

III. Discussion

8. Below, we address the following five matters that are appropriately before us as requests for clarification of Order No. 733-A: (1) stable power swings; (2) due weight to the ERO; (3) scope of Commission directives; (4) expected relay performance; and (5) relays located at generators. On these matters, we grant clarification, in part, and deny clarification, in part.

9. In addition, certain arguments raised in the requests for clarification and/or reconsideration do not pertain to clarifications made by the Commission in Order No. 733-A. Likewise, EEI/NRECA submit two affidavits to support their pleadings. As discussed below, we reject the untimely pleadings and affidavits on procedural grounds. As we explain, however, even if these pleadings and affidavits were properly before us, they would not cause us to revisit our previous decisions.7

A. Stable Power Swings

10. Reliability Standard PRC-023-1 applies to steady state8 relay loadability without regard to dynamic conditions or stable power swings.9 Rather than ordering the ERO to modify PRC-023-1 to address stable power swings, Order No. 733 directed the ERO to develop a new Reliability Standard that requires the use of protective relay systems that can differentiate between faults and stable power swings and, when necessary, phase-out relays that cannot meet this requirement. In Order No. 733-A, the Commission reaffirmed its belief that not addressing stable power swings constitutes a gap in the current Reliability Standards, clarified its expectations regarding phasing-out zone 3 relays, 10 and affirmed that the ERO has flexibility in how it addresses the directive.

11. EEI/NRECA assert the Blackout Report does not support the need for a Reliability Standard addressing stable power swings. They believe the Blackout Report neither recommends that such a Standard be created, nor does its analysis support such a Standard. According to EEI/NRECA, relays tripped during the August 2003 Blackout not because of the inability of relays to distinguish faults from stable power swings, but because of faults and severe over-loading conditions without faults. In response to the Commission’s statement regarding protection system applications currently used to block tripping of relay elements during stable power swings, 11 EEI/NRECA identify technical limitations of certain protection schemes mentioned by the Commission in Order No. 733-A. They claim that a Reliability Standard that requires relays to distinguish between stable power swings and faults threatens to decrease Bulk-Power System reliability.12 Finally, they assert that the Commission has inserted “dynamic loadability” conditions into PRC-023-1 thus introducing “a concept unknown in the industry” and contradicting the intent of the Reliability Standard. For these reasons, the Trade Associations seek clarification of the rationale supporting the directives.

Commission Determination

12. The Commission addressed this issue in both Order Nos. 733 and 733-A13 and is not persuaded that further clarification is necessary. The Blackout Report summarizes how the August 2003 Blackout cascade was triggered, identifies the role played by zone 3/zone 2 relays operating unnecessarily when faults did not exist, 14and recommends addressing the problem of such relays tripping unnecessarily.15It takes no position, however, on whether to address the problem based on either a steady-state loading approach or a stable power swings approach. Had the Blackout Report taken a position as to how to address the problem of relays tripping unnecessarily, the Commission would nevertheless be authorized by section 215(d)(5) of the FPA to identify gaps in reliability and direct the ERO to submit a new Reliability Standard or a modification to an existing Standard to address such gaps. The ERO designed Reliability Standard PRC-023-1 to address the steady-state aspects of relay loadability, 16but did not address the aspects of the problem associated with stable power swings. The Commission identified the failure to address stable power swings as a gap in the current Reliability Standards that must be addressed and directed that it be addressed in a separate Reliability Standard.17

13. As we explained in Order No. 733, the Commission’s concern that stable power swings should not cause unnecessary relay operations is consistent with good...

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