Contents
Reignition and Restrikes
• Normal and Abnormal Transients
• Reignition
– Reactor Switching
• Restrike
By :- Himanshu Bahirat
EE5220 : Power System Transients
Date:- February 22, 2010
– Capacitor switching
– Three phase capacitor switching
– Grounded vs. Ungrounded banks
Normal and Abnormal Transients
• Normal Transients
– Transients during energization
• Up to 2 p.u. voltages
• No trapped charges assumed
– Capacitor Energization inrush currents and voltages
Reactor Switching
• Trapped Energy
• High Frequency oscillations of reactor voltage
• Dielectric Breakdown
• Abnormal Transients
– During denergization
Rs
• Trapped charges
• Very high voltages and currents
• Current Chopping
– Interruption of currents
• Restrikes and Reignitions
Ls
CB
SC
Vs
Reactor
Circuit Breaker Current : Reignition
Interruption of circuit current with
reignition
Reactor Voltage :Reignition
4
900
[p.u]
After Reignition
[A]
3
700
2
500
1
Reactor Side recovery
Voltage : High frequency
300
0
Reignition : Current
100
-1
75
[A]
-100
0
10
20
(f ile Reactor_Switching_reignitions_P56.pl4; x-v ar t) c:SRC
30
40
[ms]
50
-2
50
-REACT
25
-3
0
-4
-25
8.1
8.3
8.5
8.7
8.9
(file Reactor_Switching_reignitions_P56.pl4; x-var t) v:REACT
factors:
1
8.88E-06
offsets:
0
0
-50
-75
-100
8.20
8.25
8.30
8.35
8.40
(f ile Reactor_Switching_reignitions_P56.pl4; x-v ar t) c:SRC
8.45
8.50
Reignition : Definition
Capacitor Switching
A reignition occurs when a current is interrupted
at current zero and then re-establishes itself within
one-eight of a power frequency cycle [2].
120
900
[kV]
Reignition
region
8.55 [ms] 8.60
-REACT
• Switching of normal load current
• Deenergization at system peak voltage
• Trapped charge on the capacitor
[A]
80
600
40
300
V
0
Ls
CB
V
0
-40
-300
-80
-600
-120
-900
0
10
(file Reactor_Switching_reignitions_P56.pl4; x-var t) v:SRC
20
c:XX0001-REACT
30
40
[ms]
50
Vs
Cap Bank
[ms]
9.1
Capacitor Bank Trapped Voltage and
TRV
Restrikes and Voltage Escalation
800
16
[kA]
[kV]
12
600
Trapped Voltage on Capacitor Bank
after deenergization
8
400
Circuit Breaker TRV
150
4
200
300
[kV]
0
[kV]
100
200
50
100
0
-4
-200
-8
0
0
-400
-12
-100
-50
-600
-16
0
-200
10
(file Restrike_Basics.pl4; x-var t) v:CAPA
20
30
40
[ms]
50
c:BUSA -CLRA
-100
-300
0
10
20
(f ile Restrike_Basics.pl4; x-v ar t) v :BUSB -CLRB
-150
0
10
(f ile Restrike_Basics.pl4; x-v ar t) v :CAPB
20
30
40
[ms]
30
40
[ms]
v :BUSC -CLRC
50
v :CAPC
50
• Voltage escalation with multiple restrikes
• Stored Voltage on Capacitor Bank increase with each restrike. (1st
– 3.p.u. 2nd – 5 p.u
• Very high transient current spikes
Restrikes : TRV
Restrikes :Bus Voltage
6.0
800
[V]
[kV]
3.4
500
0.8
200
-100
-1.8
-400
-4.4
-700
0
-7.0
0
10
(file Restrike_Basics.pl4; x-var t) v:BUSA -CLRA
factors:
1
7.61E-06
offsets:
0
0
20
30
40
[ms]
50
10
(f ile Restrike_Basics.pl4; x-v ar t) v :BUSA
20
30
40
[ms]
50
Restrikes :Ungrounded banks
Capacitor Bank Voltage
Restrikes :Ungrounded banks
Circuit Breaker TRV
4
3
[V]
[V]
3
2
2
1
1
0
0
-1
-1
-2
-2
0
10
(file Restrike_Basics.pl4; x-var t) v:CAPC
factors:
1
7.61E-06
offsets:
0
0
20
30
40
[ms]
50
v:CAPA
7.61E-06
0
-3
• Higher trapped voltages than the case of grounded banks.
• Restrike on phase A results in escalation on phase c.
• First restrike trapped voltage increases to about 3.5 p.u
Restrike : Definition
-4
-5
0
10
(file Restrike_Basics.pl4; x-var t) v:BUSA -CLRA
factors:
1
7.61E-06
offsets:
0
0
20
30
40
[ms]
50
v:BUSC -CLRC
7.61E-06
0
Restrike and Reignition: Comparison
The term “restrike” is defined as a re-establishment of the current,
one-quarter cycle or longer, following interruption of a capacitive
current at a normal current zero [1].
120
120
900
[kV]
[A]
Reignition
region
80
Restrike region
900
40
[kV]
600
300
[A]
80
600
0
Restrike region
40
0
300
0
0
-40
-300
-80
-600
-40
-300
-80
-600
-120
-120
-900
0
10
(file Reactor_Switching_reignitions_P56.pl4; x-var t) v:SRC
20
c:XX0001-REACT
30
40
[ms]
50
-900
0
10
(file Reactor_Switching_reignitions_P56.pl4; x-var t) v:SRC
20
c:XX0001-REACT
30
40
[ms]
50
Conclusions
References
• Abnormal transients are a result of trapped
charges and energy.
• Reignitions and restrikes can lead to very
magnitude transients.
• Multiple restrikes can damage circuit breakers
and other equipments.
• Ungrounded Banks result in higher magnitude of
transients than grounded banks.
• Can controlled with use of surge arresters.
1. N. E. Dillow, I. B. Johnson, N. R. Schultz, and A. E. Were, "Switching Capacitive
Kilovolt-Amperes with Power Circuit Breakers," AIEE Transactions, pp. 188-200, 1952.
2. R. D. Garzon, High Voltage Circuit Breakers:Design and Applications: Marcel
Dekker, Inc.,1996.
3. Shui-cheong Kam “Modelling of Restriking and Reignition Phenomena in Threephase Capacitor and Shunt Reactor Switching”.
http://www.itee.uq.edu.au/~aupec/aupec06/htdocs/content/pdf/77.pdf
4. Allan Greenwood. Electrical Transients in Power Systems. Wiley, New York,
NY.