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IEEE TRANSACTIONS ON POWER DELIVERY, VOL. 24, NO. 2, APRIL 2009
Characteristics of the Magnetic Energy Recovery
Switch (MERS) as a Series FACTS Controller
Jan Arild Wiik, Member, IEEE, Fransisco Danang Wijaya, and Ryuichi Shimada, Member, IEEE
Abstract—Developing active series compensation in transmission systems is challenging due to the large currents and voltage
capabilities required. The main purpose of this paper is to show
that the magnetic energy recovery switch (MERS) can be an attractive new series compensator by applying appropriate control.
The MERS is similar to a single-phase full bridge, meaning that
compared to the gate-commutated series capacitor, it has twice
the number of active switches. However, advantages, such as the
double voltage–current operating range, eliminating the need
for reverse blocking switches, zero current turn-on, and a lower
current conduction period of each switch can make the MERS an
attractive alternative. The basic characteristics of the MERS have
been found to be similar to a series connection of a voltage source
and a capacitor in steady state. With this dual characteristic, a
control method has been developed where the minimization of
the harmonics in the series-injected voltage and stable operation
during large setpoint changes have been achieved. The resulting
subharmonic characteristic also indicates a low risk of subsynchronous resonance. Experimental results verify the proposed
configuration and control.
Index Terms—Capacitor-compensated transmission lines,
load-flow control, power electronics, power system stability, power
transmission control.
I. INTRODUCTION
S
ERIES compensation has been used for many years as an
effective method of increasing and influencing the flow of
power in ac transmission lines. The fixed series capacitor was
the initial technology that is able to reduce the equivalent line
impedance by canceling parts of the inductive voltage drop.
Due to problems with subsynchronous resonance (SSR) and the
inability to actively control the size of the injected capacitive
voltage, power-electronics-based technologies were developed,
which are now referred to as flexible ac transmission systems
(FACTS) controllers.
The first series-connected FACTS controller was the
thyristor-controlled series capacitor (TCSC). The TCSC
has been shown not to contribute to SSR [1] and can control the
equivalent reactance. However, the operating range in steady
state is usually limited.
The static synchronous series compensator (SSSC) consists
of a voltage-source inverter and a coupling transformer injecting
Manuscript received October 29, 2007; revised March 09, 2008. Current version published March 25, 2009. Paper no. TPWRD-00656-2007.
The authors are with the Tokyo Institute of Technology, Tokyo 152-8550,
Japan (e-mail: jan.wiik@nr.titech.ac.jp; danang@torus.nr.titech.ac.jp; rshimada@nr.titech.ac.jp).
Digital Object Identifier 10.1109/TPWRD.2008.2005879
Fig. 1. Configuration of the MERS.
the series voltage into the grid [2]. It can provide controllable
compensating voltage over an identical capacitive and inductive
range, independent of the magnitude of the line current. The
operating range is significantly larger. However, this also comes
with greater complexity and costs.
The GTO thyristor-controlled series capacitor or gate-commutated series capacitor (GCSC) was introduced in 1992 [3]. It
consists of two antiparallel GTOs (or similar) in parallel with
a series capacitor. By controlling the timing of the switches,
the equivalent reactance can be decreased continuously to zero,
meaning an increase in the operating range compared to the
TCSC [4]. The subharmonic characteristics are also promising
[5]. One of the challenges with this configuration is the need for
reverse blocking switches. This increases the onstate losses. Additionally, due to the slow onswitching response of high-power
semiconductor devices, the timing of the turn-on is complex due
to the need for switching at the close to zero capacitor voltage.
The magnetic energy recovery switch (MERS) was developed for reactive compensation and voltage control of loads or
generators [6], [7]. It is attractive for high-power applications
due to simple primary control and use of asymmetric switches.
In [8] and [9], the MERS configuration was suggested to be
used for series compensation in transmission systems, where
a brief introduction to the basic principles was given. This
paper describes, in greater detail, the control characteristics for
achieving robust control as well as reduced harmonics in the
injected voltage. In particular, the resulting power-flow control
and subharmonic characteristics are investigated. Where relevant, comparison of the GCSC and the MERS is included due
to the similarities between these two devices.
The first part of this paper discusses the fundamental
principles and characteristics of the MERS for use as a series-connected FACTS controller. The second part describes the
suggested control system and the resulting series compensation
characteristics. This is followed by experimental results and
finally a conclusion.
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WIIK et al.: CHARACTERISTICS OF THE MERS AS A SERIES FACTS CONTROLLER
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Fig. 2. Switching patterns for one current cycle. The left part shows the resulting curves when controlling the minimum capacitor voltage V
and the length
of the bypass period with a reference. The upper right figure shows the MERS with an indication of the values plotted in the left. The right lower figure shows
the flow of the current through the MERS for the different areas illustrated on the left.
II. FUNDAMENTAL PRINCIPLES OF MERS
A. Configuration
The circuit configuration of the MERS is shown in Fig. 1.
It consists of four controllable switches (such as GTOs), four
diodes, and a dc capacitor. For a three-phase circuit, there will
be one MERS per phase. In principle, the MERS configuration is
the same as a single-phase full-bridge inverter (or a transformerless SSSC [10]), but the application and operation principle
differ. Compared to a conventional single-phase full bridge, the
capacitance of the dc capacitor is several times smaller, due to
the capacitor voltage being allowed to vary greatly and to become zero during each fundamental cycle (50 or 60 Hz). On the
other hand, the full-bridge configuration tries to keep a constant
voltage, resulting in a large capacitor. The MERS configuration
also uses line-frequency switching, meaning that each switch is
turned on and off only once during a fundamental cycle. This
has the advantage of reducing the switching losses, which is extremely important for high-power applications.
B. Basic Operation Principle
The primary objective of the MERS operation is being able
to control the size of the capacitive series-injected voltage. This
is achieved by controlling the path of the current through the
device. The current flows used for one fundamental cycle are illustrated on the right side of Fig. 2 and consist of charging, discharging, and bypassing the capacitor. The resulting switching
patterns and resulting waveforms are shown in the left part of the
figure. Two basic setpoints are used. The minimum dc capacitor
is controlled by entering the bypass mode when
voltage
the capacitor voltage goes below the
reference. In the
figure, this means controlling the timing when going from state
A to B or from state D to E. The other control variable is the
length of the bypass period, meaning the length of area B or E.
This is controlled by adjusting the timing when going from area
B to C or from E to F. The timing is adjusted by giving an angle
reference , which is related to the phase of the current. The
reference gives the distance from where the phase of the current
is 90 or 270 to the point of control.
and the reference, the series-injected
By setting the
voltage can be controlled from zero to the rated voltage for
all currents within the device rating. The operating range of the
MERS is illustrated in Fig. 3, together with the operating range
of the GCSC and the SSSC. The MERS can be seen to have
approximately twice the operating range of the GCSC and the
same capacitive voltage operating range as the SSSC.
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IEEE TRANSACTIONS ON POWER DELIVERY, VOL. 24, NO. 2, APRIL 2009
Fig. 4. Equivalent circuits used for studying the resulting MERS voltage. (a)
. (b) MERS represented by
MERS represented with an equivalent reactance
and a reactance
connected in series.
a voltage source
V
X
X
Fig. 3. Comparison of the voltage–current operating range for MERS, GCSC,
and SSSC.
A special case can be achieved by controlling
to zero.
For this case, the voltage across the capacitor will be zero for
parts of the period. The control of the bypass area will then result
in similar operation as for the GCSC. The control response in
this area will ideally be less than half a cycle, which is also the
case for the GCSC.
values, the response will be decided by
For higher
the current at the time of control. If the peak capacitor voltage
setpoint, it is possible to reach
is higher than the new
a new value in less than half a cycle. However, in a practical
implementation, the switching (transition from A to B) will be
performed at a value lower than the peak capacitor value in order
to avoid an initial reduction in the injected series voltage and to
prevent the voltage from being distorted during the transition.
C. Semiconductor Switch Considerations
With the high voltage and current levels used in FACTS applications, the resulting device stress during switching (on, off) and
during onstate conditions is of great importance. From Fig. 2,
the active switches in the MERS circuit (S1 – S4) can be seen
to go from the nonconducting to conducting state with zero current switching (ZCS). In the practical implementation, the active
switches are turned on well before conduction starts, ensuring
zero current turn-on with simple implementation. This is good
from a switch point of perspective since it can eliminate the need
for a turn-on snubber (anode reactor), which is usually required
for high-power semiconductors, such as GTOs and integrated
gate-commutated thyristors (IGCTs). The turn-on snubber is
usually a costly and lossy component. The GCSC must, on the
other hand, be designed for turn-on at full current.
The active switches in the MERS are turned off when the
voltage across the switches and the capacitor are equal to
. With
being equal to 0, zero voltage switching
(ZVS) will be achieved at turn-off. To also achieve the defined
must be increased.
operating range for lower currents,
values will occur at reduced currents,
However, high
limiting the maximum value of the turn-off losses. Together,
with the low switching frequency, the resulting switching losses
in the MERS circuit will be low.
One active switch in the MERS circuit will, on average, be
on one-quarter of a fundamental cycle (a single bypass can be
performed every second time in the upper and lower path). For
the GCSC, in the worst case, the average current conduction period will be half a cycle and the worst-case losses be accordingly
large. Even though the total number of switches is doubled with
the MERS solution, further investigations are needed to determine which configuration has the worst-case losses. Worst-case
losses are an important cost driver since they influence the required cooling and current ratings of the switches.
Due to only the dc voltage appearing across the MERS capacitor, reverse blocking capability of the active switches is not necessary. On the other hand, the GCSC requires reverse blocking
capability. Reverse blocking switches result in higher onstate
voltage and losses. In addition, the availability of such switches
at high-power levels is currently limited.
D. Series Voltage Characteristics
This section examines the resulting series-injected voltage
based on the control described in the previous section. The analysis is based on the equivalent circuits shown in Fig. 4.
The MERS equivalent compensating reactance (Fig. 4(a)) can
be expressed as
(1)
where
is the first harmonic voltage component of the series
is equal to
with
injected voltage, is the current, and
being the capacitance of the dc capacitor (derivation in Appendix A). All values are given in per unit and a sinusoidal current is assumed. Compensating reactance is in this paper is referred to as a quantity being positive when the reactance is capacitive. The MERS equivalent compensating reactance can be
found to be dependent on the current as well as the control set.
points and
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WIIK et al.: CHARACTERISTICS OF THE MERS AS A SERIES FACTS CONTROLLER
831
By representing the MERS as a voltage source
and a com[Fig. 4(b)], the current dependency is
pensating reactance
removed as shown in the following expression:
(2)
(3)
(4)
This means that the MERS has similar characteristics to a
voltage source and a capacitor connected in series at the fundamental frequency when operating in steady state.
, various combinations of
and will
For a given
be solutions to (1). The combination to use can be optimized in
order to reduce the harmonic distortion in the injected voltage.
The rms value of the injected series voltage is given as
Fig. 5. Optimal combination of V
=I and for different
sulting relative distortion is shown in the lower graph.
X
. The re-
(5)
is the distortion voltage. The optimal setpoint
where
combinations can be found by using (1) and (5), and minimizing
. Due to the relative complexity
the distortion component
of the equations, a numerical approach was used for solving
the equations.
being equal to one, are shown in Fig. 5.
The results, with
The upper part shows the ideal combinations of
and
. The lower part shows the relative distortion in the injected
voltage which is defined as the distortion voltage divided by the
first harmonic component of the voltage.
In a transmission system, a small series voltage injection with
high relative distortion is not a main concern due to the low influence on the bus voltages and the resulting harmonic currents
circulating. The absolute size of the distortion is more important
and has been calculated in the whole operating range as shown in
Fig. 6. The values have been related to the nominal value of the
MERS device, which, in a real case, would be several times less
than the nominal line voltage. It can be seen that the largest distortion occurs for low currents and high injected series voltage.
When limiting the MERS operating range to the same maximum
harmonic distortion level as with the GCSC, the operating range
for the MERS will be 71% larger than the GCSC.
III. CONTROL METHOD AND RESULTING SERIES
COMPENSATION CHARACTERISTICS
A. Robust and Low-Voltage Distortion Control
Section II-D identified that basic MERS operation uses two
control parameters: 1) the minimum capacitor voltage setpoint
and 2) the angle reference . Fig. 7 illustrates a possible
control system used when applying the MERS in transmission
Fig. 6. Series voltage distortion related to the nominal voltage of the MERS
device in the whole voltage–current operating range. Distortion values are illustrated with contour lines. The harmonic distortion in the GCSC will be the same
as for the MERS in the GCSC operating range.
systems. A secondary control system will be used to control
the power flow or provide active damping in the case of power
system oscillations. Due to the use of two primary setpoints for
the MERS gate control, a translation is suggested to be used between the primary gate control and the secondary power-flow
control system in order to simplify the design of the secondary
control system. This section discusses the design of such a translation. The translation should consider the following:
• MERS series voltage should increase for increasing setpoints and be close to linear;
• translation dependency on feedback variables should be
low in order to make robust control;
• low harmonic distortion.
A possible approach would be to use the MERS equivalent
as the secondary setpoint and then perform transreactance
lation based on Fig. 5. This control method would give optimal
harmonic distortion in the injected voltage. The drawback is the
direct dependency between the current and the resulting
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IEEE TRANSACTIONS ON POWER DELIVERY, VOL. 24, NO. 2, APRIL 2009
Fig. 9. Equivalent diagram of the transmission line with MERS. Voltage amplitudes of the receiving and sending end are set constant.
Fig. 7. MERS control system overview. The translation block is used between
the secondary and primary control.
steady-state validity of the proposed method, simple power-flow
estimations were performed. A grid representing the MERS in
series with a transmission line is shown in Fig. 9 and the resulting power flow can be expressed as
(6)
Fig. 8. Relationship between the setpoint from the secondary control and the
resulting compensating reactance and series voltage-source equivalent.
setpoint. This means that the translation is strongly dependent
on a feedback variable, leading to less robust control.
In order to reduce the translation dependency on the curis
rent, the following method is proposed. The reactance
first linearly increased for increasing setpoints. After a certain
setpoint is linearly inreactance value is reached, the
creased. The relationship between the secondary setpoint
and the steady-state characteristic of the MERS is shown in
Fig. 8.
will be equal to a reactance control setpoint ( )
for values less than 0.5; hence, the reactance control area. For
will translate to a series
values higher than 0.5, a given
voltage source equivalent value, hence, a voltage-control area.
reference is also adjusted in
In the voltage-control area, the
order to achieve low distortion and to reduce the dependency
on the current feedback. In summary, the dual characteristic
of the MERS device (series connection of the reactance and
voltage source) introduces some complexity when translating
a secondary control setpoint to primary control setpoints.
B. Power-Flow Control Characteristics
A method for translating an external setpoint to internal setpoints was suggested in the previous section. To confirm the
where
is the voltage magnitude of the receiving and sending
end of the transmission line,
is the transmission-line reactance, and is the voltage phase-angle difference between the
sending and receiving end. A similar equation can be found for
is not part
the SSSC, but then, the compensating reactance
of the expression [11].
The power-flow control characteristics of the MERS have
been investigated by using (6) and the parameters shown in
Table I as an example. Fig. 10(a) shows the resulting power
flows for different setpoints and different phase-angle differences. It can be seen that the characteristics in the reactance
control and the series voltage-control area are different. The reactance control area is more dependent on the current while the
series voltage-control area has a constant and similar slope for
all three cases. The linear slope shows that the characteristic is
very similar to that of a pure series-injected voltage. This means
in the voltage-control area
that the influence of varying the
is limited (low-current dependency). Fig. 10(a) also shows that
is limited
depending on the size of and the current, the
due to the MERS voltage-rating constraint.
The power-flow control range for the MERS, GCSC, and
SSSC are shown in Fig. 10(b) for different voltage phase-angle
differences. For the sample case, the rated voltage with a rated
compensating reactance occurs at which is equal to 30 . For
less than 30 , the control range of the MERS is larger than
that of the GCSC and half of the SSSC. The large control range
for low can be important in applications related to loop flows.
Additionally, it will provide increased potential for damping oscillations in the power system.
C. Subharmonic Characteristics
The subharmonic characteristics of series-connected FACTS
devices can be performed by connecting the device to a current
source and observing the voltage response [12]. Fig. 11 shows
the circuit that was used in the investigations. Due to difficulty
in obtaining analytical expressions of the frequency response,
simulations were used as a basis. A simulation model with the
control fixed to the first harmonic of the current component was
used [ideal phase-locked loop (PLL)]. In order to investigate the
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WIIK et al.: CHARACTERISTICS OF THE MERS AS A SERIES FACTS CONTROLLER
833
Fig. 11. Circuit for investigation of the subharmonic characteristics for the
MERS device.
Fig. 10. Steady-state power-flow estimations. (a) Dependency between the
U
setpoint and power flow for three voltage phase-angle differences.
(b) Power-flow control range of three technologies for different voltage
phase-angle differences.
TABLE I
PARAMETERS USED IN MERS POWER-FLOW CALCULATIONS
subharmonic characteristics of the MERS, steps were carried
out as follows.
• For each subharmonic frequency, a current of the given
frequency was injected, superimposed on to a current of the
base frequency of 50 Hz.
• The resulting voltage waveform was evaluated for a given
time period and the amplitude of the first harmonic and the
given subharmonic frequency were identified with Fourier
analysis.
• Based on Fourier analysis, the equivalent resistance and
reactance for the different subharmonic frequencies were
estimated.
Several tests were performed with a different equivalent reactance
. The resulting subharmonic characteristic of the
MERS device is shown in Fig. 12. The characteristics changes
immediately when entering the subharmonic frequency domain.
The equivalent negative MERS reactance is reduced for decreasing frequencies, and there is also a large equivalent resistance in the whole subharmonic frequency domain damping
Fig. 12. Subharmonic response of the MERS device. Reduced capacitive reactance and a rong resistive characteristic in the subharmonic frequency domain
indicate good subharmonic characteristics and a low chance for initiating SSR.
possible subharmonic oscillations. These two observations indicate that the installations of MERS in a transmission line will
not initiate subharmonic resonance.
An illustration of a time response of the MERS for a subharmonic frequency of 10 Hz is shown in Fig. 13. It can be seen
that the subharmonic of the current and the voltage is almost in
phase, meaning a highly resistive characteristic. By analyzing
the active power frequency spectrum, resulting resistive power
at a given subharmonic frequency can be found to be equal to
the power injected into the fundamental frequency. This must
be the case since there is no active element in the MERS device
where steady-state power can be stored.
equal to zero, the subharmonic characteristic of
With
the MERS will be similar to that of the GCSC. Investigations
show that the influence of the PLL is important for the GCSC
characteristics [5]. Future work should study the development
of optimal PLL for the MERS.
IV. EXPERIMENTAL RESULTS
In order to investigate the performance and stability of the
proposed configuration, some experiments were conducted. The
configuration of the experimental setup is shown in Fig. 14.
The MERS, a Y – transformer and inductors are connected
in series to form a loop. The transformer connection shifts the
voltage 30 , meaning that power will automatically flow in the
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IEEE TRANSACTIONS ON POWER DELIVERY, VOL. 24, NO. 2, APRIL 2009
Fig. 13. MERS voltage response with subharmonic current injection at 10 Hz,
overloaded on a 50-Hz base current. The resulting subharmonic components of
voltage and current have been extracted and can be seen to be almost in phase,
indicating a resistive characteristic.
1 transformer creates a 30
Fig. 15. Experimental results when applying step in series-injected voltage
from close to zero to rated voltage. (a) Time trends with an initial current of
1 A. (b) The initial current is 3 A.
Fig. 14. Illustration of experimental setup. The Yphase shift and initiates loop flow.
TABLE II
SPECIFICATIONS OF THE EXPERIMENTAL CIRCUIT FOR POWER-FLOW CONTROL
circuit when voltage is applied. As a result, the equivalent of
the configuration is shown in the lower part of Fig. 14, meaning
good representation of a transmission line. The specifications of
the experimental circuit are given in Table II.
setpoints and using the
The control is based on giving
translation shown in Fig. 8. SH7045 microcontroller hardware
was used, and control was performed 512 times every 50-Hz
cycle. Monitoring and giving setpoints were performed from a
desktop PC.
In order to test the stability of the proposed control system,
setpoint changes were applied, and the resulting relarge
sponse was studied. The setpoint change was chosen so that the
initial series MERS voltage was close to zero and the voltage
after the step was close to the rated voltage of 130 V. Tests
were performed for different power-supply voltages, meaning
different initial current flows.
Fig. 15(a) shows the experimental results when the initial current was 1 A. The increase in series-injected voltage depends on
building up a voltage across the dc capacitor. With a small initial
current, this buildup takes longer than for the case with larger
current. The time response indicated in the figure has been defined as the time it takes for the rms current to exceed 90% of
the steady-state current step change. Fig. 15(b) shows the case
for a larger initial current of 3 A. The time response has now
been improved.
Fig. 16 gives a summary of the step change experiments.
The no-compensation and full-compensation currents are indicated in the upper part of the figure. The area between the
two lines indicates the current control range for the MERS. The
control range when using a GCSC with same voltage rating is
also indicated. This shows that the MERS can improve the control range for small initial current flows. The lower part of the
figure shows the time response for the different steps applied.
The aforementioned 90% criterion has been used for evaluation.
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WIIK et al.: CHARACTERISTICS OF THE MERS AS A SERIES FACTS CONTROLLER
Fig. 16. Estimations of the time response for different power-supply voltages
and initial currents.
When the power-supply voltage and the no compensation current increases, the time response improves. For higher current,
the response will be similar to that of the GCSC, since the rewill be low. For very low initial currents, the required
sponse will be reduced. The results indicate that for initial currents higher than 0.12 p.u. (1 A), the response will be better than
100 ms.
Steps going from rated voltage compensation to close to zero
compensation were also investigated and were found to have a
response between 50 and 80 ms. In general, the up and down
step responses were found to be limited by the ability of the
PLL to track the resulting current. This limit was taken into account in the design of the control; however, a detailed discussion regarding optimal step response and PLL design is out of
the scope of this paper.
835
moving the turn-on snubber. On the other hand, the GCSC must
be designed to turn-on at full current. The MERS switch turn-off
at high current is performed when the voltage across the capacitor is low, keeping the off switching losses low. Due to the presence of the dc voltage across the capacitor, reverse blocking capability of the switches is not needed. The GCSC requires, on
the other hand, reverse blocking capability, which has less availability for high-power ratings and also increased onstate voltage
and losses. Finally, the onstate period is a maximum quarter of
a cycle, while the GCSC is maximum on half a cycle. A long
onstate period means higher losses per switch and the need for
higher current ratings and cooling for each switch.
The transient response of the suggested system has been investigated with small-scale experiments by applying step in setpoints from zero compensation to rated compensation. Stable
operation was demonstrated with fast response. For small current levels, the response is slower than the case for larger current
levels, due to the need for voltage build up across the capacitor.
For initial current levels higher than 0.12 p.u., the response in
the current change was faster than 100 ms.
Subharmonic analysis has been performed by using idealized simulations. Resistive characteristics have been identified
in the subharmonic frequency domain, indicating a reduced risk
of subsynchronous resonance. The characteristics are similar to
that of the GCSC in the reactance control area. Future studies
should be performed to investigate the influence of PLL design
and verification on the benchmark grid.
In summary, the investigations indicate the potential for using
the MERS as a series compensator in transmission systems.
APPENDIX
DERIVATION OF MERS VOLTAGE EQUATIONS
V. CONCLUSION
The MERS is suggested as a new series-connected FACTS
device. The MERS is similar to a single-phase full bridge, but
the capacitor is several times smaller. A control method has been
suggested, where by controlling the current path through the
device, it is possible to inject zero to rated voltage for all currents
within the device rating.
In steady state, the resulting characteristic is similar to a capacitor and a voltage source connected in series. The optimal
combinations of reactance and voltage setpoints have been developed so that harmonics in the injected voltage are kept low,
while, at the same time, robust control is achieved. By limiting the harmonic distortion to the same level as for the GCSC,
the current-voltage operating range will be 71% larger than the
GCSC. The larger operating range is shown to provide improved
power-flow control capability at low rotor-angle differences,
which also implies improved potential for damping oscillations
in the power system.
The semiconductor device stress resulting from the suggested
control and configuration has been found to be low. Switch
turn-on is performed at zero current, giving potential for re-
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correction,” in Proc. PCIM Eur., Nuremberg, Germany, 2006.
[8] J. A. Wiik, F. D. Widjaya, T. Isobe, T. Kitahara, and R. Shimada,
“Series connected power flow control using magnetic energy recovery
switch (MERS),” presented at the PCC, Nagoya, Japan, 2007.
[9] J. A. Wiik, F. D. Wijaya, and R. Shimada, “An innovative series
connected power flow controller, magnetic energy recovery switch
(MERS),” presented at the Power Eng. Soc. General Meeting, Tampa,
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53–58, Jan. 2001.
Jan Arild Wiik (M’06) was born in Lorenskog,
Norway, in 1973. He received the M.Sc. degree in
electrical engineering from Norwegian University
of Science and Technology, Trondheim, Norway, in
1998.
From 1998 to 2005, he was a Researcher with
ABB Corporate Research, Billingstad, Norway. In
2005, he joined the Solutions Research Organization
at the Tokyo Institute of Technology, Tokyo, Japan,
in the Solutions Research Organization. Tokyo.
His main fields of interest are power electronics
and power systems, including applications in the area of grid integration of
renewable energy.
Fransisco Danang Wijaya was born in Yogyakarta,
Indonesia, in 1974. He received the B.E.E and M.E.E
degrees from Gadjah Mada University, Yogyakarta,
Indonesia, in 1997 and 2001, respectively, and is currently pursuing the Ph.D. degree in energy sciences
at the Tokyo Institute of Technology, Tokyo, Japan.
He has been a Lecturer and Researcher in the Electrical Engineering Department at Gadjah Mada University since 1998. His research interests are in the
area of energy conversion, electrical machines, and
power electronics.
Ryuichi Shimada (M’94) was born in Tochigi,
Japan. He received the B.E.E and M.E.E degrees
from the Tokyo Institute of Technology, Tokyo,
Japan, in 1970 and 1972, respectively, and the
D.Eng. degree in electrical engineering from the
Tokyo Institute of Technology, Tokyo, Japan, in
1975.
From 1975 to 1988, he was a Researcher of
Nuclear Fusion development and an Electrical Engineer at the Japan Atomic Energy Research Institute,
Tokai-mura, Ibaraki, Japan. He joined the development of the world largest Tokamak-type fusion experimental machine JT-60.
He was Group Leader of the power supplies development of JT-60. In 1988,
he was a responsible Director of JT-60 operation and experiment. In 1983,
he joined the Princeton Plasma Physics laboratory at Princeton University to
begin the large Tokamak Fusion Test Reactor. In 1988, he became an Associate
Professor in the Department of Electrical and Electronics Engineering at the
Tokyo Institute of Technology. In 1990, he became a Professor and joined the
Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology,
where he is currently Professor with the Department of Energy Science.
Prof. Shimada received the 1985 Outstanding Achievement Award from the
Institute of Electrical Engineers of Japan and the 1976 and 2000 Outstanding
Paper Award from the Institute of Electrical Engineers of Japan. Recently, he
has received the 2003 Excellent Published Book Award from the Institute of
Electrical Engineers of Japan.
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