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ERCOT Planning Horizon SOL Methodology Update. Jeff Billo. Background. Per FAC-010-2.1 the Planning Authority (ERCOT) is to establish a documented SOL methodology for its area ERCOT has issued a change to the methodology and communicated that change per Requirement 4
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ERCOT Planning Horizon SOL Methodology Update Jeff Billo RPG
Background • Per FAC-010-2.1 the Planning Authority (ERCOT) is to establish a documented SOL methodology for its area • ERCOT has issued a change to the methodology and communicated that change per Requirement 4 • Why are we making these changes? • Better align planning horizon SOL/ IROL methodology with TPL-003 and PRC-023 • Learn from Southwest Event • What changes are we making? • General rewrite • Add SOL/ IROL identification for steady-state cascade conditions • Better define IROL identification • Effective January 1, 2013 RPG
How does PRC-023 fit in? • Defines transmission circuit relay loadability requirements for Transmission Owners • Provides 13 different methods for TOs to set their phase protective relay settings • Based on this we have used the conservative assumption that transmission circuits loaded above 150% of their normal rating or 115% of their emergency (2-hour) rating will trip • Assumption used for screening purposes only • Limitation • Applies only to facilities 200 kV or higher or 100-200 kV facilities that the Planning Coordinator identifies as ‘critical to the reliability of the BES’ RPG
PRC-023 Side Note • Assume all 345 kV facilities set per PRC-023 • Run separate analysis to identify 138 kV circuits that will lead to Cascade event if relays are set between 100% loading and PRC-023 loadability requirements • Report 138 kV circuits as ‘critical to reliability’ if meet this criterion RPG
How is ERCOT applying this? • In ERCOT’s TPL standard analysis, no facilities should be loaded above 100% for Category A or B contingencies • If the analysis shows that for a Category C (multi-element) contingency facilities will be loaded above 150% of the normal rating or 115% of the emergency rating then we will assume that the facility will trip • If this causes a Cascade condition then ERCOT Planning will investigate and take one or more of the following actions if the Cascade condition is confirmed (per Category C Planning process): • Plan an upgrade • Plan a Mitigation Plan (including RAPs and/or load shed) RPG
How is ERCOT applying this? • An SOL will be created when … • Manual system adjustment (switching, load shed, etc.) is required in order to prevent cascading or voltage collapse; • A stability limit is identified; • Voltage stability margin is less than 5% for NERC Category B contingencies or 2.5% for Category C contingencies; or • Post disturbance frequency is not within 59.4 Hz to 60.4 Hz • The SOL will be classified as an IROL if the load loss (either via manual load shed or as a consequence of the event) is greater than four times 1% of the load in the case • The IROL Tv will be defined as the lower of the relay trip setting time delay or 30 minutes RPG
Comments or Questions? Send formal comments to: jbillo@ercot.com March 12, 2010 RPG
Appendix March 12, 2010 RPG
Quick Example on Facility Ratings (courtesy of WECC) Load Shed (15 min) Limit Exceedance = Go beyond limit Limit Violation = Exceed limit for a time duration longer than required mitigation time Emergency (2 hour) Normal (continuous) 0 MVA RPG
Quick Example on Facility Ratings Load Shed (15 min) Emergency (2 hour) Normal (continuous) Operate in this range all you want. Nothing is being exceeded, nothing is being violated. 0 MVA RPG
Quick Example on Facility Ratings Load Shed (15 min) • Operate in this range for no more than 2 hours: • You are exceeding the normal rating. • You are violating the limit if you operate in this range for longer than 2 hours. Emergency (2 hour) Normal (continuous) 0 MVA RPG
Quick Example on Facility Ratings • Operate in this range for no more than 15 minutes: • You are exceeding the emergency rating. • You are violating the limit if you operate in this range for longer than 15 minutes. Load Shed (15 min) Emergency (2 hour) Normal (continuous) 0 MVA RPG
Quick Example on Facility Ratings • You can’t operate over this limit. If you do you may damage equipment, cause safety problems and/or trip the facility • You are exceeding the load shed rating. • To exceed the highest time-limit rating established is to violate the limit. Load Shed (15 min) Emergency (2 hour) Normal (continuous) 0 MVA RPG
Quick Example on Facility Ratings Normal (continuous) = Emergency (2 hour) = Load Shed (15 min) • If all ratings are the same, you can never operate over the normal limit. If you do you may damage equipment, cause safety problems and/or trip the facility • You are exceeding the load shed rating. • To exceed the highest time-limit rating established is to violate the limit. 0 MVA RPG