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

2. 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

3. 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

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

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

6. 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.

7. 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

8. 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

9. 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

10. 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.

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

12. UFLSRG 59.5 SILT ----- (~3,200 MW) 59.3 NW 5.6% 59.2 NW 5.6%
2014 current WECC Plan
SILT (~3,200 MW)
NW %
NW %
WECC other %
NW %
WECC other %
NW %
WECC other 6.3%
NW %
WECC other 6.7%
WECC other 6.7%

13. 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

14. 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

15. 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

16. 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.

17. 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.

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

19. 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 MW’s
Load Interrupted MW’s *

20. *
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 *

21. *
07/16/96
Frequency Chart *

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

23. 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 *

24. 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

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

26. 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

27. Questions?