Title: Subsynchronous Resonance
Next Group:
Next Step:
Status: Approved on 06/13/2017
Effective Dates:

All sections except for Section




Date Gov Body Action Taken Next Steps
06/13/2017 BOARD Approved
05/25/2017 TAC Recommended for Approval Revision Request Consideration
04/13/2017 PRS Recommended for Approval Revision Request Consideration
03/09/2017 PRS Recommended for Approval PRS for Impact Analysis review
06/11/2014 PRS Deferred/Tabled PRS for consideration
05/15/2014 PRS Deferred/Tabled PRS for consideration
09/19/2013 PRS Deferred/Tabled PRS for consideration

Voting Record

Date Gov Body Motion Result
06/13/2017 BOARD Approved NPRR562 as recommended by TAC in the 5/25/17 TAC Report. Passed
05/25/2017 TAC To recommend approval of NPRR562 as recommended by PRS in the 4/13/17 PRS Report. Passed
04/13/2017 PRS To endorse and forward to TAC the 3/9/17 PRS Report, as revised by PRS, and Revised Impact Analysis for NPRR562 with a recommended priority of 2017 and rank of 1990. Passed
03/09/2017 PRS To recommend approval of NPRR562 as amended by the 3/3/17 ERCOT comments Passed
06/11/2014 PRS To table NPRR562. Passed
05/15/2014 PRS Table NPRR562 for one month. Passed
09/19/2013 PRS To table NPRR562. Passed

Vote tallies here reflect individual votes, not the weight of the votes by market segment. Affirmative votes are not recorded in these vote tallies. For additional details on the voting record, please consult the Recommendation or Action Report, or the official vote tally if available, as posted in the key documents.


Status: Approved
Date Posted: Aug 12, 2013
Sponsor: ERCOT
Urgent: No
Sections: 2.1, 2.2, 3.1.1,, 3.22 (new), 3.22.1 (new), (new), (new), (new), (new), 3.21.2 (new), and 3.22.3 (new)
Description: This Nodal Protocol Revision Request (NPRR) creates new requirements for the identification, study, mitigation of, and protection against Subsynchronous Resonance (SSR).
Reason: SSR is a potentially harmful phenomenon involving coincident oscillation between two or more Transmission Elements or Generation Resources at frequencies lower than the normal operating frequency (60 Hz) of the ERCOT System. The ERCOT System has recently become more vulnerable to SSR because of the introduction of series capacitors for voltage support, although other Transmission Elements (including poorly tuned power electronic devices) and generator control systems can also create SSR. Without proper mitigation, SSR can quickly destroy resonating Transmission Elements and/or Generation Resources and lead to cascading Outages. It is therefore essential to carefully study and mitigate this risk. This NPRR is intended to create a process for investigating and addressing SSR risk and to clarify the responsibilities of the various Entities affected.

Key Documents

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