Underfrequency Load Shedding Assessment Report Kent Bolton January 30, 2014 JGC Meeting SLC, UT

2 UFLSTF formed in 2009 by PCC & OC o Review effectiveness of Plan Designed to arrest declining frequency Assist recovery of frequency after UFLS events Coordinated Plan

3 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

4 Coordination exists within the Coordinated Plan Anti-stalling and overshoot in accordance with Coordinated Plan Main Findings, cont.

5 13hsp1aspring on-peak 13hs2summer on-peak 13ls1summer off-peak 14hw2winter on-peak 14lw1winter off-peak Base Cases

6 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

7 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 Islands, cont.

8 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 o Doesn’t increase recovery frequency 30-sec, 60-sec stages required? Results

9 Abnormal topology – September 2011 o San Diego, IV, CFE – 50% imports Variable Generation o Increased amounts impact freq. recovery Results, cont.

10 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 Conclusions

11 Plot

12 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

13 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.

14 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 Recommendations, cont.

15 UFLSRG Mtg – SLC, Ut Feb , Data Request o GO Submittals due 6/1/14 o UFLS Entity Submittals due 7/1/14 Next Steps

Questions?