2010 International Conference on Power System Technology
A Novel Design of Flexible Controlled Shunt
Reactor
Zheng Wei-jie, and Zhou Xiao-xin, Fellow, IEEE
tackle with for the extra and ultra high voltage line [9-11].
This paper proposed a novel design of flexible controlled
Abstract—This paper proposed a novel design of flexible
controlled shunt reactor (FCSR) which can suppress shunt reactor (FCSR) which can suppress over-voltages of
over-voltages of high voltage transmission line in various high voltage transmission line in various situations flexibly, it
situations flexibly, it not only has the smoothly and wide range not only has the smoothly and wide range continuously
continuously controllable features for the power frequency
over-voltage regulation, but also has the fast-switching ability controllable features for the power frequency over-voltage
and the nonlinear characteristics which can competent to rapid regulation, but also has the fast-switching ability and the
change in tide as well as the switching surge or impulse nonlinear characteristics which can competent to rapid change
overvoltage control. It has stable control characteristics and fast in tide as well as the switching surge or impulse overvoltage
transient response which can meet the various needs of the control.
system, and has a broad application prospects. The magnetic
Flexible controlled shunt reactor also can simplify the
circuit structure and working principle of FCSR are analyzed as
system
reactive power and voltage control in power grid,
well as the technical features in the paper. Computer simulation
results used in standard power system example and practical dynamically compensate charging power in transmission line,
operation parameters confirmed the above advantages and eliminating generator self-excitation, damping system
effectiveness. It opens a new way to the voltage control and resonance, suppress secondary arc current and so on [11]-[15],
reactive power regulation of ultra high voltage transmission line.
it has excellent stable control characteristics and fast transient
response which can meet the various needs of the system, and
Index Terms-- flexible controlled shunt reactor, over-voltage
has a broad application prospects.
suppression, reactive power regulation,
The magnetic circuit structure and working principle of
flexible
controlled shunt reactor are analyzed as well as the
I. NOMENCLATURE
technical features in the paper. Computer simulation results
Ultra High Voltage, UHV
used in standard power system example and practical
Static Var Compensator, SVC
operation parameters confirmed the above advantages and
Flexible Controlled Shunt Reactor, FCSR
effectiveness of flexible controlled shunt reactor.
Electromagnetic transient software of ETSDAC has contained
II. INTRODUCTION
the model by program, it's novel, effective and practical,
Ultra high voltage (UHV) alternate current power which not only provides an innovative design for controlled
transmission lines have tremendous capacitive charging power, shunt reactor, but also opens a new way to the voltage control
huge trend of rapid change in tide, and limited insulation and reactive power regulation of ultra high voltage
margin[1]-[3], which cause enormous challenges to the system transmission line.
reactive power regulation, over-voltage suppression.
The traditional reactive power compensation devices III. THE CLASSIFICATION AND DESCRIPTION OF OVERVOLTAGE
[4-8]such as: general high voltage shunt reactors, low-voltage
IN ULTRA HIGH VOLTAGE TRANSMISSION LINE
switching shunt capacitors and reactors group, generator-phase
Power system over-voltage is due to the power system
operation and static var compensator (SVC) are generally failure and / or switching caused electromagnetic energy
unable to meet the need of both reactive power regulation and conversion, which brought about transient or longer duration
for over-voltage suppression.
of higher voltage than rated and may pose a threat to the
The transient over-voltage and switching surge result from power electrical devices [1]. Over-voltage is an
different causes and have diverse performance and harm to the electromagnetic transient phenomena in power system, which
power transmission which are also complicated problem to can divided into switching and temporary over-voltage.
This work was supported in part by The National Key Technology R&D
Program in 11th five-year plan of China
Zheng Wei jie is in China Electric Power Research Institute, Haidian
District of Beijing (dianlidianzi_@163.com).
Zhou Xiao xin is in China Electric Power Research Institute, Haidian
District of Beijing
978-1-4244-5939-1/10/$26.00©2010 IEEE
Temporary over-voltage is which occurred after the transition
process in a sustained longer than 0.1s to a few seconds or
even hours of continuing over-voltage [16]-[19]. As the
modern extra and ultra high voltage power system protection
are maturing, there is little temporary over-voltage occurrence
in the extra and ultra high voltage grid which appears over the
2
duration more than a few seconds. Temporary over-voltage, it
also includes frequency and resonant over-voltage.
Frequency of power frequency over-voltage is line
frequency or close to it [1]. The cause of frequency
over-voltage including the capacitance effects in non-loaded
line, asymmetry ground fault caused normal phase voltage
hoist, load mutation, and so on, which is closely related to the
system construction, capacity, parameters and mode of
operation[20]. Generally, the amplitude of frequency
over-voltage is limited, while its duration is long. Power
frequency over-voltage is important to the extra and ultra high
voltage system, because:
1,It directly affects the amplitude of switching over-voltage
2, It is important basis of arrester rated voltage.
3, It affects the relay level
4, It may pose threat to the security of system device.
Switching over-voltage is caused by the transient transition
course aroused by the breaker and disconnecting link
operation, which not only include the normal operation, such
as the closing and reclosing over-voltage in the line and
transformer or reactor, but also include over-voltage in the
opening and fault as well as clearance of fault [1]. The
switching over-voltage has the characteristics of high
amplitude, high frequent oscillation, heavy damping, brief
duration， and so on. The affection of switching over-voltage
to device insulation and protection equipments mainly
depends on the amplitude and waveform and duration. The
wave front gradient of switching over-voltage is generally
lower than thunder over-voltage.
Switching overvoltage is an important dependence of
insulation in ultra voltage transmission line.
Basic principle of high-voltage magnetically controlled
shunt reactor is the use of ferromagnetic materials, by
changing the rectifier to the field winding excitation into DC,
to change the saturation of ferromagnetic materials, thereby
changing the equivalent permeability [3].
Fig. 1.
Panoramic photo of magnetically controlled shunt reactor equipments
Fig. 2. Diagram for couple curve of magnetization
By changing the flow angle of silicon control, the direct
exciting current changed, thereby the saturation of iron
changed accordingly.
Metal oxide surge arrester is also known as
pressure-sensitive arresters. It is a new composite metal oxide
surge arresters without spark gaps [23]-[26]. Varistors are
polycrystalline semiconductor ceramic components with the
ideal valve characteristics sintered by zinc oxide or bismuth
oxide and other metal oxide. It present great resistance in
frequency voltage, which can be rapid and effective
suppression frequency continuous current, so it is dispense
with spark gap to crush out the continued flow caused by the
frequency arc; In the over-voltage, its resistance has become
very small, can discharge lightning current splendidly.
Therefore, metal oxide surge arrester has a wide application in
power system.
In recent years, with the metal oxide surge arrester
manufacturing level increases, the ability to limit overvoltage
rising. At the present stage of ultra high voltage research, the
substation and line side have adopted the metal oxide surge
arrester rated voltage of 828kv
Fig. 3.
Compound metal oxide surge arrester equipment
As showed in the figure 2, with the increase of iron saturation,
Metal oxide surge arrester generally used in conjunction
the magnetic conductivity decreased [20]-[22], so the output of with the closing resistor, different system operation and line
flexible controlled shunt reactor is increased.
length has different levels of closing resistor voltage, Input
3
resistance after the closing, continuous investing time to
increase closing resistance can reduce over-voltage of closing
statistics, the effect of the way depends on the transmission
system.
As the requirements of west to east power transmission,
most of the ultra voltage transmission line is long, the
charging power is huge, the high voltage shunt reactor is
necessary to compensation. As the shunt reactor is connected
to the line, the inductive reactive power compensated to the
capacitive power, decreased the frequency voltage [11]-[12].
In the generally under compensated condition, the input
impedance from the front line is capacitive, while the
numerical value is increased, non-load line capacitive current
decreased, in the same source reactor situation, the front
voltage rise is decreased. As a result, the input of shunt reactor
can decreased the front and end frequency over-voltage.
The flexible controlled shunt reactor can be regulated on
line, which can meet multi-aspect needs. In the extra\ultra high
voltage grid, the flexible controlled shunt reactor has the
following functions
It can simplify the reactive and voltage control measures.
As the output of flexible controlled shunt reactor can be
regulated continuously according to the system needs. In the
variation range of system, there is no necessary to equip other
reactive power devices, so the flexible controlled shunt reactor
can simplify reactive and voltage control.
It can suppress the frequency over-voltage. In the state of
normal operation, the flexible controlled shunt reactor can
smoothly regulate output to stabilize the voltage according to
the transmission line. In the time of load rejection, flexible
controlled shunt reactor can quickly adjust to the requested
capability.
Flexible controlled shunt reactor can dynamically
compensate the capacitive reactive power. The power system
should prepare sufficient dynamic reactive power to insure the
system stability and economy operation.
The flexible controlled shunt reactor can solve the problem
and contradiction between overvoltage suppression of long
line heavy load and reactive compensation, which can meet
the needs of multi-aspects.
The configuration design of flexible controlled shunt
reactor is showed in the figure, the magnetically controlled
shunt reactor is located in the center, while the fixed capacity
shunt reactors are arranged in both sides, the capacity
combination is flexible according to the situation, which can
compensate the reactive power quickly. The metal oxide surge
arrester is designed into the top of flexible controlled shunt
reactor, which can suppress the switching surge and
over-voltage.
Flexible controlled shunt reactor can quickly compensate
the reactive power in time of need, also can be smoothly
regulated to approach the objective voltage in precision, which
has comprehensive advantages and reduce the investment in a
better effect.
Fig. 4. Schematic diagram of flexible controlled shunt reactor
The operation theory and reactive capacity calculations of
flexible controlled shunt reactor were as follows:
In the normal operation, K1，K2，K5 closed，K3，K4
open, set the connection voltage is U , the input capacity
can be calculated:
X1 X 2
X1 + X 2
X 12 X mc
X eqI =
X 12 + X mc
X1 X 2
X mc
X1 + X 2
=
X1 X 2
+ X mc
X1 + X 2
X 1 X 2 X mc
=
X 1 X 2 + X 1 X mc + X 2 X mc
X 12 =
QI =
=
while，
(1)
(2)
U2
X eqI
U 2 ( X 1 X 2 + X 1 X mc + X 2 X mc )
X 1 X 2 X mc
I
X mc
= f (α I )
(3)
(4)
If the capacitive charging power of transmission line
increased, the voltage of connection point rise, then K3 closed,
the input capacity calculations were as follows:
4
X 1 X 2 X mc
X 1 X 2 + X 1 X mc + X 2 X mc
X eqII =
X 1 X 2 X mc
X3 +
X 1 X 2 + X 1 X mc + X 2 X mc
X3 ⋅
Q IV =
X 2 X mc X 3 + X 1 X 2 X mc )
Q II =
(5)
IV
open K1,K2, The input capacity Q calculations of flexible
controlled shunt reactor were as follows:
U
X eqII
I
X mc
= f (α I )
X eqV = X mc
X3X4
X3 + X4
(7)
X
= X 1 X 2 X 3 X 4 X mc ( X 1 X 2 X 3 X 4 + X 1 X mc X 3 X 4 +
X 2 X mc X 3 X 4 + X 1 X 2 X mc X 3 + X 1 X 2 X mc X 4 )
(9)
2
U
X eqIII
V
mc
2
(15)
2
U
U
= V
V
X eq X mc
= f (α )
IV. SIMULATION AND RESULTS
The design of flexible controlled shunt reactor proposed in
the paper is verified by the standard single-generator infinite
system example in use of the electromagnetic transient
software of ETSDAC which is research and developed
independently by CEPRI. The diagram circuits are as
following figure 5 and 6. BUS-3 is or not connected with the
flexible controlled shunt reactor separately in different
example as comparison. The faults occurred in time 2 second
in both examples, the instantaneous voltage waveforms were
recorded and compared in stable and transient state, error
comparisons was made to confirm the validity of proposed
flexible controlled shunt reactor.
= U 2 ( X 1 X 2 X 3 X 4 + X 1 X mc X 3 X 4 +
X 2 X mc X 3 X 4 + X 1 X 2 X mc X 3 + X 1 X 2 X mc X 4 ) /
X 1 X 2 X 3 X 4 X mc
while，
III
X mc
= f (α III )
(10)
(11)
When there is heavy load in the transmission line, the
voltage of connection fell, then open K1, The input capacity
Q IV calculations of flexible controlled shunt reactor was as
follows:
X eqIV =
X mc X 2
X mc + X 2
Fig. 5.
(12)
(16)
while，
(17)
α is the flow angle α of silicon control, which can be
regulated to change the direct exciting current, the saturation
of iron changed accordingly, as well as the capacity of
controlled shunt reactor, consequently the voltage can be
regulated smoothly.
(8)
X3X4
X 1 X 2 X mc
⋅
X + X 4 X 1 X 2 + X 1 X mc + X 2 X mc
= 3
X3X4
X 1 X 2 X mc
+
X 3 + X 4 X 1 X 2 + X 1 X mc + X 2 X mc
Q III =
QV =
(6)
If the capacitive charging power of transmission line
increased, the voltage of connection point rise, if it was
insufficient to close K3, then close K4. The input capacity
calculations of flexible controlled shunt reactor were as
follows:
X eqIII
(14)
2
X 1 X 2 X mc ) / X 1 X 2 X 3 X mc
X 34 =
(13)
If opening K1 was insufficient to improve the voltage, then
= U 2 ( X 1 X 2 X 3 + X 1 X mc X 3 + X 2 X mc X 3 +
while，
IV
X mc
= f (α IV ) ，
while，
= X 1 X 2 X 3 X mc ( X 1 X 2 X 3 + X 1 X mc X 3 +
2
U 2 U ( X mc + X 2 )
=
X eqIV
X mc X 2
System diagram for comparison simulation calculation
5
Fig. 6. System diagram for flexible controlled shunt reactor simulation
calculation
1.5011
1.5021
1.5031
1.5041
1.5051
1.5061
1.5071
1.508
1.5091
1.51
1.5111
1.512
1.5131
1.514
1.5151
1.516
1.5171
1.518
1.5191
1.52
1.5211
1.522
1.5231
1.0021
0.94174
0.78921
0.55943
0.27488
‐0.03657
‐0.34444
‐0.61859
‐0.83219
‐0.96433
‐1.0021
‐0.94173
‐0.7892
‐0.55941
‐0.27487
0.036577
0.34445
0.6186
0.8322
0.96434
1.0021
0.94174
0.78921
‐0.46928
‐0.17249
0.1412
0.44108
0.69778
0.88619
0.98787
0.99285
0.90065
0.7203
0.46945
0.17265
‐0.14104
‐0.44091
‐0.69762
‐0.88603
‐0.9877
‐0.99269
‐0.90049
‐0.72014
‐0.46929
‐0.17249
0.1412
‐0.5328
‐0.76925
‐0.93041
‐1.0005
‐0.97267
‐0.84963
‐0.64343
‐0.37426
‐0.06846
0.24403
0.53263
0.76908
0.93023
1.0003
0.97249
0.84946
0.64326
0.37409
0.068288
‐0.2442
‐0.5328
‐0.76925
‐0.93041
TABLE II
AMPLITUDES OF VOLTAGE IN TRANSIENT STATE AFTER FLEXIBLE CONTROLLED
SHUNT REACTOR REGULATION
Time/(s) Fig. 7.
Instantaneous value waveform of fault frequent overvoltage
Fig. 8. Instantaneous value waveform of FCSR voltage control adjustment
simulation
TABLE I
AMPLITUDES OF VOLTAGE IN TRANSIENT STATE BEFORE FLEXIBLE
CONTROLLED SHUNT REACTOR REGULATION
Time/(s) 1.5001
Phase A(p.u) 0.96434
Phase B(p.u) ‐0.72014
Phase C(p.u) ‐0.24421
3.5
3.5011
3.5021
3.5031
3.504
3.5051
3.5061
3.5071
3.508
3.509
3.5101
3.5111
3.512
3.513
3.5141
3.5151
3.516
3.517
3.5181
3.5191
3.52
3.521
3.5221
3.5231
Phase A(p.u) 0.98263
0.87088
0.67403
0.41134
0.10852
‐0.20478
‐0.49789
‐0.74213
‐0.91359
‐0.99547
‐0.97977
‐0.86803
‐0.67118
‐0.40849
‐0.10568
0.20762
0.50073
0.74496
0.91641
0.99829
0.98259
0.87085
0.67399
0.4113
Phase B(p.u) ‐0.31303
‐0.00331
0.30663
0.58646
0.80878
0.95184
1.0016
0.95326
0.81149
0.59019
0.31102
0.001302
‐0.30864
‐0.58846
‐0.81078
‐0.95384
‐1.0036
‐0.95525
‐0.81348
‐0.59218
‐0.313
‐0.00329
0.30666
0.58649
Phase C(p.u) ‐0.6696
‐0.86757
‐0.98066
‐0.9978
‐0.9173
‐0.74706
‐0.50373
‐0.21113
0.1021
0.40528
0.66876
0.86673
0.97982
0.99696
0.91646
0.74622
0.50289
0.21029
‐0.10293
‐0.40612
‐0.66959
‐0.86756
‐0.98065
‐0.99779
6
From the above waveforms and data comparison, the
voltage regulation was in high precision, the waveforms
before and after fault almost fit together perfectly.
The requirement of UHV frequency overvoltage is under
1.4pu, flexible controlled shunt reactor can smoothly regulate
the output volume automatically according to the transmission
power, which can stabilize the voltage.
The designed model also reflects the flexible control of
switching over-voltage, which will be introduced with the
controller algorithm in another paper.
[12]
[13]
[14]
[15]
V. CONCLUSIONS
The paper analyzed the functions and application prospects
of voltage flexible controlled shunt reactor which is more
suitable than SVC for extra and ultra power grid. A designed
model was proposed which describes the configuration and
flexible characteristics. It not only reflects the smoothly and
continuously controllable features of saturated magnetic
circuit, but also be suitable for the quickly compensation
response. Computer simulation results used in standard power
system example confirmed the accuracy of model. It is novel,
neat, numerical stability and practical, which provides the
necessary implement for the voltage regulation of ultra high
voltage transmission line. The simulation experience for
switching surge suppression and control methods will be
introduced in further research.
[16]
[17]
[18]
[19]
[20]
[21]
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VII. BIOGRAPHIES
Zheng Wei-jie was born in 1982, PHD, He is in China
Electric Power Research Institute
Zhou Xiao xin is in China Electric Power Research Institute, Haidian
District of Beijing，IEEE fellow