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Power System Dynamics Analysis
Complexity in the WSCC
August 10, 1996 System Disturbance
David P. Chassin, October 16, 2002
Contact: david.chassin@pnl.gov
6Nov98
August 1996 West Coast Blackout
Summary of Events
WSCC 8-10-96 15:48 PAST major disturbance
4 islands, 7.5M customers out up to 9 hours
Initiating event: 500 kV Keeler-Allston flashover to trees
Trip cause: poor right-of-way maintenance
Numerous supporting events
Follow-up events
COI limit lowered to 3200 MW (Aug 11)
Account for limits at McNary (exciter) and The Dalles (fish)
Raised Aug 12-14 to 3600 MW to avoid blackouts in CA
2
PNNL and Power Systems
DOE Transmission Reliability Program
Real-Time Grid Reliability Management
Reliability and Markets, Load as a Resource
Distributed Energy Resources Integration
Infrastructure Assurance Outreach Program
Utility vulnerability assessments
Interaction with NERC, others on security topics
Interest in SCADA security
Energy System Transformation Initiative
Integrated econophysics modeling and simulation
Next generation power technology development
3
Wide-Area Measurement System
Dynamic monitor network supports advanced
analysis
“Better information supports
better - and faster - decisions.”
Disturbances Unobserved
response
System planning
Power
System operation
System
Automatic control
Observed
response
Measurement
Decision Information Based
Processes Information
System
4
Real-Time System Data
Collected from various monitors throughout the grid
Bonneville Power Administration Phasor Data Concentrator
5
Power System Measurement Tools
Tools for managing data & signal analysis
6
“Ringdown” Analysis Tool
Advanced dynamic analysis
Malin MW
Extracting a linear model 1 20 0
Brake in sertion #2, 09/04/97
(Alberta stro ng ly co nn ected)
Un filtered sign als
from measured data PACI Mode: 0.294 Hz @ 5 .3 % damping
Albe rta : 0.418 Hz @ 5.1% da mping
1 10 0
1 00 0
model fitting w indow
9 00
Da ta c ollec ted on D ittme r P PS M
s ample r ate = 60 /se cond
Re fer e nc e tim e 0 9-0 4-97 23 H4 2m 35 s
1 65 1 70 1 75 1 80
Time in Seco nd s
•Dynamic analysis
•Model validation
•Control design
7
Advanced Dynamic System
Analysis and Model Validation
August 10, 1996 post-disturbance analysis
Determine if model
calibration is needed.
4600 Observed COI Power (Dittmer Control Center)
4400
4200
4000
4600 Simulated COI Power (initial WSCC base case )
4400
4200
4000
0 10 20 30 40 50 60 70 80 90
Time in Seconds
Currently working with western utilities to improve power grid models
8
Power System Econophysics
3
1.6 2 1.6Q 2
PQ 4π
2
PJM 1999 Load/Price Probability Distributions Qe
20.85
100%
2π 0.85
Q = Qmax (11/P2)4.54 80%
$1,000
Probability
60%
$750
40%
Price ($/MWh)
$500 20%
0%
$250
20000 25000 30000 35000 40000 45000
Quantity (MWh/h)
$0 100%
20000 30000 40000 50000
Quantity (MWh/h) 80%
Probability
Cout Qin 60%
40%
Abstract Control control Thermodynamic
process process
Transactive Cprofit
State m data State x
Qwaste
20%
Machine 0%
Cin Qout
$10 $100 $1,000
Price ($/MWh)
9
Grid Friendly™ Appliances
60.020
60.000
Four Corners Unit 5 Tripped with 710 MW on May 8, 2002 At 13:38
PDT
Grid-friendly appliances…
With GFA: Frequency Excursion Arrests at 59.950 Hz within 0.7 …rapid, automatic response to grid crises
59.980 sec.
…platform for active communication &
Frequency (Hz)
59.960 control
59.940
…pre-heat/pre-cool to coast through peaks
…utilize & value thermal storage
…increase reliability & security
59.920
59.900 …unnoticeable by consumer
59.880
Without GFA: Frequency Drops to 59.886 Hz within 5.8
sec.
…mass customization/marketing
59.860
0.0 10.0 20.0 30.0 40.0 50.0
Seconds (from 13:38:20 PDT)
Grid-Friendly Appliance Controller
Loads and Reserves on a
Typical U.S. Peak Day 106 =100
Residential
(non-GFA)
10%
Industrial
28% Residential
(GFA) 20%
GFA potential
exceeds US
Operating operating reserve
Commercial
29%
reserves requirements! “…given enough ants, you can move a mountain!...”
13% impromptu reaction from a utility power engineer
10
Overview of WSCC August 10, 1996
15:48 PAST Disturbance
Based on WSCC Disturbance Report
Approved by WSCC Operations
Committee on October 18, 1996
High northwest transmission loading
High imports to CA
Heavy imports from Canada
and Idaho
COI at 4750 MW
Similar to conditions prior to
7/2/96 disturbance
Warning signs visible
Previous high-load issues
Small power/large voltage
swings
Suggested voltage support
problems in NW
12
Equipment out of service
Lines
500 kV: Big Eddy-Ostrander,
John Day-Marion, and Marion-
Lane (reactive support around
Portland) flashover to trees
115 kV: Allston-Rainer degraded
x x hdwr, Longview-Lexington cable
installation.
x
Breakers
500 kV: Marion, Keeler
(modifications)
Transformers
500/230 kV: Keeler (modification)
Static VAR Comp (SVC)
Keeler reduced support to
500 kV (tied to 230 kV side)
13
Triggering Events
15:42:37 Keller-Allston
Sags into trees, flashes, trips
Overload par-lines hold 5 min
McNary react-power at max
15:47:29 St. Johns-Merwin
Lines trip on relay malfunc.
KA par-line loads increase
! ! ! 15:47:36 Ross-Lexington
!
Tree flashover and trip
207 MW from Swift lost
System voltage sags
! 15:47:36 McNary
Units trip, exciter problem
System power/voltage osc. begins
ID-UT-CO-AZ-NM-NV Surge
COI power flows down east side
Out-of-step trips
CA-AZ remain tied together
14
Final Result
28,000 MW of under-frequency load shedding
20,000 MW of undesired generation loss
Four major islands
Northern California (North of LA to Oregon border)
Losses: 11,600 MW load; 7,900 MW generation
Frequency excursions: 58.54 – 60.7 – 58.3, restored in 2.5 hrs.
Southern California (SoCal, NV, AZ, NM, El Paso, Baja)
Losses: 15 820 MW load; 13,500 MW generation
Frequency excursions: 61.3 – 58.5, restored in 70 min.
Northern (BC, OR, WA, MT, WY, ID)
Losses: 2,100 MW load; 5,700 MW generation
Frequency excursions: 60.4, restored in 7 minutes
Alberta
Losses: 970 MW load; 146 MW generation
Frequency excursions: 60.4 – 59.0, restored in 6 minutes
15
Open Questions re. Complexity
Report only identifies the incontrovertible points
and fails to address more controversial questions:
Why was line maintenance inadequate?
Why was system operated in single-contingency mode?
Why did AZ-CA separation scheme fail to operate?
Why did models fail to predict oscillations?
Why did system damping fail?
Lesson for us:
Don’t go just by the official reports. Much more is not
reported or discussed because of sensitivities. The
social dynamics of a tightly knit community factors into
what is knowable. We have to look deeper.
16
Problems Persist
WECC Oct 8 2002 15:31 PDT
60.050
60.000
480 MW generation dropped
59.950
2900 MW generation tripped
1400 MW Chief Joe brake inserted
59.900
59.850
Freq
59.800
59.750
59.700
59.650
~350 MW load loss
59.600
~86 MW UFLS
59.550
22:30:43.20 GMT
22:30:51.84 GMT
22:31:00.48 GMT
22:31:09.12 GMT
22:31:17.76 GMT
22:31:26.40 GMT
22:31:35.04 GMT
22:31:43.68 GMT
22:31:52.32 GMT
22:32:00.96 GMT
22:32:09.60 GMT
Time
17
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