WECC Planning Committee
Underfrequency Load Shedding
Review Group Update
March 25, & 26, 2014
UFLSRG
Underfrequency Load Shedding Review
Group (UFLSRG)
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2
Philip Augustin
Kent Bolton
Desmond Chan
Eleanor Ewry
Roy Gearhart
Irina Green
Mark Hanson
Richard Hydzik
Danny Johnson
Gerald Keenan
Stephanie Lu
Grace Martinez
Chris Pink
Steve Rueckert
Jerry Rust
Hari Singh
Dede Subakti
Branden Sudduth
Shilpa Toppo
Mike VanRemoortere
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.
o Other measures
o
o
o
o
3
Typical Frequency Event WECC
(Average of 5 events, T-5 to T+60)
Typical WECC Frequency Excursion
60.02
60
Point A
59.98
Point B
59.96
Point C
59.94
59.92
59.9
0
6
12
18
24
30
Seconds
36
42
4
48
54
60
After a disturbance – loss of generation
- what happens?
If frequency is still declining then what?
5
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.
6
UFLSRG Concepts to Remember
o UFLS Plan is to protect against cascading
resource loss
o WECC RAS 1 is a separation Scheme –
 COI and Four Corners
 North Island
 South Island
7
UFLSRG
o 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
8
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
9
UFLSRG
o 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.
10
UFLSRG
o Islands Simulated
 WECC
 North Island (Canada, further separation Alberta)
 South Island
 SW Outage event and all combinations
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UFLSRG
2014 current WECC Plan
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12
59.5
59.3
59.2
59.1
59.0
58.9
58.8
58.7
58.6
58.5
58.3
SILT
----- (~3,200 MW)
NW
5.6%
NW
5.6%
WECC other 5.3%
NW
5.6%
WECC other 5.9%
NW
5.6%
WECC other 6.3%
NW
5.6%
WECC other 6.7%
WECC other 6.7%
Case-Islands
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14HS4
island
Pgen
WECC
Neutral
173,594 167,475 0
Pload
PSched 10%
Export
6,445
NORTH 76,655
67,167
SOUTH 96,939
Import
100,307 -6,445
Feb 2014
15%
20%
25%
16,747
25,121
33,495
41,869
13,162
16,520
19,878
23,237
3,586
8,601
13,616
18,632
Area
unit
Pmax
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
1200
30
PG AND E
Diablo
Canyon
70
PSCOLORADO Comanche3
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
54
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Area_Name
805
MSSC Loss
WECC 14,141 MW
N-Island 6,647 MW
S-Island 7,494 MW
Project Loss
Pmax
ALBERTA
Genesee
1,371
ARIZONA
Palo Verde
4,132
2,830
50
B.C.HYDRO
Gordon
Shrum
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
2,400
30
PG AND E
Diablo
Canyon
70
PSCOLORADO Comanche
22
SAN DIEGO
Encina
946
64
SIERRA
Valmy
565
24
SOCALIF
Ormond
1,500
52
FORTISBC
Waneta
480
73
WAPA R.M.
Craig
63
WAPA U.M.
Ft Peck
Area
54
14
15
Area_Name
1,530
1,374
108
Project Loss
WECC 33,344 MW
N-Island 16,409 MW
S-Island 16,935 MW
UFLSRG
o Performance
 The WECC Plan performed as designed under
simulations
 Load Shedding Occurs;
 Frequency decline was arrested;
and,
 Recovery was observed.
16
UFLSRG
o SW Outage Events
 Initial outage exceeded the 25% resources loss of
the UFLS Plan, therefore not a credible island for
UFLS – beyond standard requirements
o Canada and Alberta
 During the past 10 years these islands have not
formed due to an underfrequency event.
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UFLSRG
o Review of the last unplanned large loss of
generation
o June 14, 2004
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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
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Event Summary
 Bird Excrement Caused Fault on WestwingLiberty 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
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20
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TIME
21
8:00:58
7:58:05
7:55:12
7:52:19
7:49:26
7:46:34
7:43:41
7:40:48
7:37:55
Frequency Chart
Frequency(HZ)
60.1
60
59.9
59.8
59.7
59.6
59.5
Generation Tripped
 Palo Verde Units 1, 2 & 3
 Red Hawk Units 1 & 2
 Duke Arlington Unit 1
 Other Units
3796 MW
206 MW
420 MW
188 MW
Total 4610 MW
22
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
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UFLSRG Future 2014-15
o Islands Simulated
 E.B.1 & E.B.2 - Planning Coordinators shall
participate and identify one or more islands to serve
as the basis…
o UFLSRG has reviewed the past 10 years and
configuration of the Western Interconnection
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UFLSRG
o Proposed Islands to be Simulated 2014-15
 WECC
 North Island
 South Island
o Motion to Approve the Islands to be Simulated
by the WECC UFLSRG for the period 2014-15
are: WECC, North Island, and South Island.
25
UFLSRG
o UFLS Review Group leadership
 To quote Forrest Gump “ I’m not a smart man”
 Volunteered for one year in 2008
o Transferring leadership to Chris Pink
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Questions?