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Underfrequency Load Shedding Assessment Report Kent Bolton. January 30, 2014 JGC Meeting SLC, UT. Coordinated Plan. UFLSTF formed in 2009 by PCC & OC Review effectiveness of Plan Designed to arrest declining frequency Assist recovery of frequency after UFLS events. Main Findings.
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Underfrequency Load Shedding Assessment Report Kent Bolton January 30, 2014 JGC Meeting SLC, UT
Coordinated Plan • UFLSTF formed in 2009 by PCC & OC • Review effectiveness of Plan • Designed to arrest declining frequency • Assist recovery of frequency after UFLS events
Main Findings • Coordinated Plan maintained since 1998 with last review in 2009 • UFLS data base developed through PRC-006-WECC-CRT-1 • UFLS relay data consistent with WECC Base Case data • Several simulations evaluated – frequency in each case returned to safe operating range
Main Findings, cont. • Coordination exists within the Coordinated Plan • Anti-stalling and overshoot in accordance with Coordinated Plan
Base Cases • 13hsp1a spring on-peak • 13hs2 summer on-peak • 13ls1 summer off-peak • 14hw2 winter on-peak • 14lw1 winter off-peak
Islands • WECC-WI Island (WI) • Canada Island (C) • North Island (N) • North Island w/o Alberta (NBF) • North Island w/o Canada (NWC) • AESO Island (A) • BC Hydro Island (BF) • South Island (S) • Imperial Valley Island (IV) • Mexico CFE Island (CF)
Islands, cont. • San Diego Island (SD) • San Diego Area Island w/ Mexico and Imperial Valley (SIC) • San Diego Area Island w/ Imperial Valley (SDI) • San Diego Area Island w/ Mexico (SDC) • Impact of Variable generation
Results • Normal topologies exhibit successful demonstration of UFLS • Including 25% imbalance cases, all frequencies recovered to > 58 Hz but not > 59.5 Hz • 15-sec anti-stalling stage • Doesn’t increase recovery frequency • 30-sec, 60-sec stages required?
Results, cont. • Abnormal topology – September 2011 • San Diego, IV, CFE – 50% imports • Variable Generation • Increased amounts impact freq. recovery
Conclusions • Coordinated Plan is adequate in safety-net use and application • Increased use of anti-stall component • WECC Base Case and program model should be reviewed
Recommendations • Assure automatically switched reactive devices are modeled • Assure voltage regulators and PSS are correctly represented • Review gen settings to assure correct representation • Continue to annually simulate island scenarios
Recommendations, cont. • Load controller and governor settings in WECC base cases need review • Review WECC base cases for accuracy under extreme events – long and short term • Review initial stage load shedding and anti-stalling settings to determine if adjustments are necessary
Recommendations, cont. • Review simulation results to determine if Coordinated Plan needs modification • Review V/Hz results and determine a defined method for measurement of performance • Include composite load model in next year’s assessment
Next Steps • UFLSRG Mtg – SLC, Ut Feb. 18-19, 2014 • 2014 Data Request • GO Submittals due 6/1/14 • UFLS Entity Submittals due 7/1/14