WECC Planning Committee Underfrequency Load Shedding Review Group Update March 25, & 26, 2014

UFLSRG Underfrequency Load Shedding Review Group (UFLSRG) Philip Augustin Richard Hydzik Jerry Rust Kent Bolton Danny Johnson Hari Singh Desmond Chan Gerald Keenan Dede Subakti Eleanor Ewry Stephanie Lu Branden Sudduth Roy Gearhart Grace Martinez Shilpa Toppo Irina Green Chris Pink Mike VanRemoortere Mark Hanson Steve Rueckert Gregory Vassallo

After a disturbance – loss of generation - what happens? Devices respond to a frequency change Frequency sensitive load – motors Frequency sensitive generation – governors Automatic Generation control – AGC Contingency Reserve Deployment – generation, curtailment interruptible load, etc. Other measures

Typical WECC Frequency Excursion * 07/16/96 Typical WECC Frequency Excursion Point A Point B Point C Seconds * 4

After a disturbance – loss of generation - what happens? If frequency is still declining then what?

Purpose of UFLS Last automatic protection scheme to arrest the frequency decline after a disturbance Load Shedding Occurs; Frequency decline was arrested; and, Recovery was observed.

UFLSRG Concepts to Remember UFLS Plan is to protect against cascading resource loss WECC RAS 1 is a separation Scheme – COI and Four Corners North Island South Island

UFLSRG PRC-006-1 Broken down into these Requirements Joint review including historical events - E.B.1 Identified Island – E.B.2 A Regional UFLS Plan & simulation - E.B.R3. through R5. Adopted by the WECC Board A Regional UFLS Data Base – R6. thru R9. Established through PRC-006-WECC-CRT-1

UFLSRG Simulation of the Plan Once every 5 years - By November 1, 2014 (first year) – E.B.4 UFLSRG Identified Islands and Scenarios E.B.1 & E.B.2 based upon prior simulations and Southwest Outage 14 different scenarios

UFLSRG Simulation and Report Findings WECC technical review and formatting – will be posted for review – approval at July meetings Performance of the various UFLS settings demonstrated the applied relays will provide adequate protection for the resource losses totaling up to 25% or greater in the defined islands Frequency excursion will experience conditions that would have 58.0Hz encroached but not passed Studies illustrated that the frequency arrestment utilized the full 5-step load shed and resulted in acceptable trajectory for frequency recovery In some cases, a few of the island configurations are showing 15-seconds anti-stalling features being engaged.

UFLSRG Islands Simulated WECC North Island (Canada, further separation Alberta) South Island SW Outage event and all combinations

UFLSRG 59.5 SILT ----- (~3,200 MW) 59.3 NW 5.6% 59.2 NW 5.6% 2014 current WECC Plan 59.5 SILT ----- (~3,200 MW) 59.3 NW 5.6% 59.2 NW 5.6% 59.1 WECC other 5.3% 59.0 NW 5.6% 58.9 WECC other 5.9% 58.8 NW 5.6% 58.7 WECC other 6.3% 58.6 NW 5.6% 58.5 WECC other 6.7% 58.3 WECC other 6.7%

Case-Islands 14HS4 island Pgen Pload PSched 10% 15% 20% 25% WECC 173,594 167,475 Neutral 16,747 25,121 33,495 41,869 NORTH 76,655 67,167 Export 6,445 13,162 16,520 19,878 23,237 SOUTH 96,939 100,307 Import -6,445 3,586 8,601 13,616 18,632 Feb 2014

MSSC Loss WECC 14,141 MW N-Island 6,647 MW S-Island 7,494 MW unit Area Area_Name unit Pmax 54 ALBERTA Genesee 500 14 ARIZONA Palo Verde12 2756 50 B.C.HYDRO Revelstok345 1,505 11 EL PASO Riogd_G8 150 60 IDAHO Brownlee 5 259 21 IMPERIALCA El Steam 4 80 26 LADWP Scatt3g 460 20 MEXICO-CFE LRP-u4 290 62 MONTANA Colstrip 800 18 NEVADA HigginS3 330 10 NEW MEXICO San Juan 4 544 40 NORTHWEST CGS 1150 65 PAC J Bridger 12 1100 30 PG AND E Diablo Canyon 1200 70 PSCOLORADO Comanche3 805 22 SAN DIEGO Encina 5 329 64 SIERRA Valmy G2 300 24 SOCALIF Ormond2 750 52 FORTISBC Waneta 120 73 WAPA R.M. MBPP-1 605 63 WAPA U.M. Ft Peck 108 WECC 14,141 MW N-Island 6,647 MW S-Island 7,494 MW

Project Loss WECC 33,344 MW N-Island 16,409 MW S-Island 16,935 MW Area Area_Name Project Loss Pmax 54 ALBERTA Genesee 1,371 14 ARIZONA Palo Verde 4,132 50 B.C.HYDRO Gordon Shrum 2,830 11 EL PASO Newman6 288 60 IDAHO Brownlee 746 21 IMPERIALCA El Steam 263 26 LADWP Inter Mtn 1,900 20 MEXICO-CFE Pres. Juarez 1,128 62 MONTANA Colstrip 2,306 18 NEVADA Lenzie 1,170 10 NEW MEXICO San Juan 1,834 40 NORTHWEST Coulee 3ph 4,598 65 PAC J Bridger 2,200 30 PG AND E Diablo Canyon 2,400 70 PSCOLORADO Comanche 1,530 22 SAN DIEGO Encina 946 64 SIERRA Valmy 565 24 SOCALIF Ormond 1,500 52 FORTISBC Waneta 480 73 WAPA R.M. Craig 1,374 63 WAPA U.M. Ft Peck 108 WECC 33,344 MW N-Island 16,409 MW S-Island 16,935 MW

UFLSRG Load Shedding Occurs; Frequency decline was arrested; and, Performance The WECC Plan performed as designed under simulations Load Shedding Occurs; Frequency decline was arrested; and, Recovery was observed.

UFLSRG SW Outage Events Canada and Alberta Initial outage exceeded the 25% resources loss of the UFLS Plan, therefore not a credible island for UFLS – beyond standard requirements Canada and Alberta During the past 10 years these islands have not formed due to an underfrequency event.

UFLSRG Review of the last unplanned large loss of generation June 14, 2004

Disturbance Overview June 14, 2004 at 0741 MST * 07/16/96 Disturbance Overview June 14, 2004 at 0741 MST Westwing 500 kV / 230 kV and Palo Verde 500 kV subs cleared Generation Tripped - 4610 MW’s Load Interrupted - 996 MW’s *

* 07/16/96 Event Summary Bird Excrement Caused Fault on Westwing-Liberty 230 kV Line Westwing WW1022 breaker failed to trip (single point of failure – Auxiliary Relay) APS System Operators thought WW 1022 breaker was in the open position during restoration *

* 07/16/96 Frequency Chart *

Generation Tripped Palo Verde Units 1, 2 & 3 3796 MW * 07/16/96 Generation Tripped Palo Verde Units 1, 2 & 3 3796 MW Red Hawk Units 1 & 2 206 MW Duke Arlington Unit 1 420 MW Other Units 188 MW Total 4610 MW *

System Restoration System Frequency recovered within 16 minutes * 07/16/96 System Restoration System Frequency recovered within 16 minutes COI was over its OTC limit for 13.5 minutes APS and SRP SOs focused on getting power to Palo Verde *

UFLSRG Future 2014-15 Islands Simulated E.B.1 & E.B.2 - Planning Coordinators shall participate and identify one or more islands to serve as the basis… UFLSRG has reviewed the past 10 years and configuration of the Western Interconnection

UFLSRG Proposed Islands to be Simulated 2014-15 WECC North Island South Island

UFLSRG UFLS Review Group leadership To quote Forrest Gump “ I’m not a smart man” Volunteered for one year in 2008 Transferring leadership to Chris Pink

Questions?