Upload
others
View
1
Download
0
Embed Size (px)
Citation preview
Copyright © SEL 2004
Local and Wide-AreaNetwork Protection Systems
Improve Power System Reliability
A. Guzman
D. Tziouvaras
E. O. Schweitzer
Schweitzer Engineering Laboratories, Inc.
K. E. Martin
Bonneville Power Administration
Power System Challenges
l Load-generation separation
l Environmental restrictions (NIMBY)
l Limited network growth
l Network resource optimization
l Separate companies for G,T,D
Main Causes ofWide-Area System Disruptions
l Voltage collapse
l Rotor angle instability
Voltage Collapse Per Carson Taylor
“A power system at a givenoperating state and subject to a
given disturbance undergoes voltage collapse if post-disturbance equilibrium voltages are below acceptable limits”
Power System Voltage Stability, EPRI,
ISBN 0-07-063184-0
Generation ≠ Load DuringTransient Angle Instability
Generators cannot deliver their total output power to the system
Voltage Collapse EvolvesInto Angle Instability
0.1 0.2 0.3 0.4 0.5 0.6 0.7Time (s)
Vo
ltag
e (p
u)
-0.8
-0.4
0
0.4
0.8
Slow Fault Clearing TimeInitiates Voltage Collapse
Zone2
Zone2
Zone2
51
51
Restof PowerSystem
Reverse Zone 3 Element Operated During Low Voltage Conditions
X
R
Overload
Out-of-Step Detection LogicAvoids Zone 1 Tripping
Transmission Line TrippingDuring System Oscillation in Idaho
Wide-Area Protection Systems
Protection systems to minimize riskof wide-area disruptions and increase
system power transfer capability
Wide-Area Network Undervoltage Load-Shedding Scheme (BC Hydro)
Rest ofPowerSystem
Load Load
LoadArea
1U/V
Area2
U/V
U/VArea 3
U/V Load Shedding Is EnabledOnly if Synchronous Condenser Output Is Close to Rated Output
t1
MVAR Output Close to Rated
U/V
ShedBlock 1
Area 1
Area 2
Area 3
Area 3SynchCond
AND1
AND2
OR 1 AND
3
t2
t3
ShedBlock 2
ShedBlock 3
U/V
U/V
Area 2 Generation Depends on System Real-Time Transmission Capability (CFE)
Area 1HeavyLoad
Real Power andOpen Line Monitor
Area 3LightLoad
Area2
Line 1Line 2Line 3
Scheme Sheds Generation WhenTwo Lines Open and P > 1100 MW
Line 1
Line 2
Line 3
TwoLinesOpen
1100 MW
AndTrip ExcessGenerationin Area 2
Line Open
Σ–+
Line Open
Line Open
MW
MW
MW
Wide Area Protection Schemesin the Western United States
Kemano
Colstrip
Malin
John Day
Peace River
Midpoint
Jim Bridger
IPP
CaptainJack
GrandCoulee
ChiefJoseph
Four Corners
Tesla
SanOnofre
Palo Verde
Enhance Power Transfer Through Wide-Area Network Protection (US)
Line
3Li
ne 2
Line
1North Intertie
South Intertie
East Intertie
Area 4Area 1
Real Power andOpen Line Monitor
Area 2 Area 3
Real PowerMonitor
Line 4
Line 6Line 5
Line
7
Line
8
Pacific NW
PG&E SCE
Inter-Area Power Flow Determines Set of Actions to Avoid Disruption
0-1500
A2 to A3(MW)
A2 to A1(MW)
I,II
IV
III
V
IV III
I,II V
No Actionsin Area 2
900
0
3675
Set IV Actions for Three-Line-Open Condition Between Area 1 and Area 2
l Area 2 informs Area 1 of line-open conditions in the intertie
l Pacific NW WAPS trips generation
l System separates into north and south networks
l System sheds pump load in Area 2
l Resistor dynamic brake inserted at Area 1
Model to Study Voltage Stability(Kundur, Power System Stability and Control)
11
1
10
Open
Open
5
2
376
8
9
Z=Constant
P=1692 MWQ=485 MVAR
P=207 MWQ=58 MVAR
Z=Constant
I=Constant
P=3844 MWQ=1194 MVAR
Voltages for Buses 8 and 9 DropBelow the 95 Percent Threshold for
Two-Line Loss Between Buses 6 and 7
0 5 10 15 20 25 30
Vol
tage
(pu
)
Seconds0.8
0.9
1
0.95Bus 8
Bus 9
Threshold
Inverse-Time Undervoltage Elements Shed Low-Voltage Loads First
0.2 0.4 0.6 0.8Voltage (pu)
Sec
onds
0
5
10
15
Bus 8 Voltage Recovers Afterthe ITUV Element Drops the Bus 9 Load
0 5 10 15 20 25 30
Vol
tage
(pu)
Seconds0.8
0.9
1
1.1Bus 8
Bus 9
Synchronized Phasor Measurements in the Western United States
Synchronized PhasorMeasurement System at BPA
PMU
PDC
StreamReaderdisplay and recording
Direct dataexchange withother utilities
Phasor DataConcentrator
(PDC)
SCADA
Data storage
Analog datameasurement–substations
Data inputand management
–control center
Other displays
Operation monitors–display and alarms Real-time
system controls
PMU
PMU
PDC
Voltage andreactivestability
Inter-areaangle limits
StreamReader Application
Wide-Area Protection / Control UsingSynchronized Phasor Measurements
PDC(data concentrator
that inputsand correlatesphasor data)
SVC
WACS Controller(calculations,
outputs)
Wideband data output by Ethernet
Digital outputs toWAPS controller
WAPS Controller(access to
trip circuits)
Dynamic Brake
Generator Trip
PMU
PMU
PMU
Voltage Swing for a DoublePalo Verde Outage (2700 MW)
Vol
tage
(pu)
CouleePearl
JohnDay
Olinda
Malin
Seconds
Tuesday, June 03 13:56:56 2003
200 2 4 6 8 10 12 14 16 18
1.2
1.10
1.00
0.90
0.80
Response to 750 MW Lossin Northeast Washington
Freq
uenc
y D
evia
tion
From
Nom
inal
- m
Hz
51 52 53 54 55 56 57
Seconds - starting at 15:41:44 on 7/7/99
Malin
GrandCoulee
Vincent
–.020 Hz
0.9 s
0
–20
–40
–60
Grand Coulee Frequency,Coulee-Vincent Phase Angle,
Los Angeles Generator Output
54
Generator Outputin Los Angeles Area
Phase Angle FromCoulee to Vincent
InitialFault
Grand CouleeFrequency
mH
z/D
egre
es
Seconds - starting at 15:41:44 on 7/7/9951 51.5 52 52.5 53 53.5
90
80
70
60
50
40
30
20
1400 MW Dynamic Brakeat Chief Joseph Substation
Conclusions (1)
l Use breaker failure together with direct transfer trip instead of Zones 2 and 3 for backup protection
l Timely, appropriate actions are required to avoid system disruptions
l Wide-area protection systems minimize risk of system disruptions and increase power transfer capacity
Conclusions (2)
l Time-synchronized measurements improve power system dynamics assessmentt They can be used for analysis and controls
l Inverse-time undervoltage elements optimize load shedding to prevent system voltage collapse without communications!