Enhancement of Power Quality using Tapped Inductor FC-TCR
R. V. D. RAMA RAO
Department of Electrical and Electronics Engineering, Narasaraopeta Engineering College
Narasaraopet, Andhra Pradesh, India
S. S. DASH
Department of Electrical and Electronics Engineering, SRM University, Chennai, India
Abstract: This Paper deals with digital simulation of FC-TCR, which can enhance the Power Quality of a power system.
Reactive power is controlled by using tapped inductor system. This system reduces THD in the line current. Smooth
variation of reactive power can be obtained by varying the firing angle of TCR. This circuit eliminates switching
transients and improves the life of the capacitors. The simulation was performed using MATLAB Simulink and the
simulation results are presented. The simulation results are similar to the analytical results.
Introduction
T closed) to zero (Thyristor valve T open) by the method
of firing delay angle control. The fixed capacitor (FC)
and the TCR constitute a basic var generator arrangement
(FC-TCR). The constant capacitive var generation of C
is opposed by the variable var absorption of the TCR.
In the control of electric power systems, systems and
procedures are used to compensate dynamically the
detrimental effects of non-linear loads. The compensation
process should be carried out without important alteration
of the source signals quality. Some benefits are expected
using compensation losses reduction in the distribution
lines, harmonic content aminoration, and power factor
improvement. The dynamic behavior of industrial loads
requires the use of compensator that can be adopted to
load changes. Unfortunately, the techniques frequently
used for Compensation is based on circuit controllers
that alter the waveform of the signals subject to the
control. Such is the case of the static compensator, which
must perform harmonic cancellation, reactive power
compensation, power factor correction, and energy
saving. Although the static compensator is commonly
used and studied under sinusoidal voltage conditions,
waveforms corresponding to the controlled current
present high harmonic content.
Calculation of the firing angle can be made in the
time domain or in the frequency domain, using different
approaches. Assuming the supply voltage is sinusoidal,
calculation of the firing angle is obtained with minimum
complexity. However, the modification of TCR firing
angle, increasing from limits � = 0 to ��= � 2 , produces
increasing distortion of the current in the TCR branch,
and consequently that of the line current. It increases the
rms value of the line current and the THD, and
deteriorates the power factor. This situation is still more
degraded where voltage is not a pure sine wave.
This paper focuses on the Thyristor-Controlled
Reactor (TCR). The compensator with TCR controls the
current in the reactor L from a maximum (Thyristor valve
FC-TCR System
E-mail: munu_dash2k@yahoo.com, ramrvd@yahoo.com
I J E E S R, 3(1) June 2013
In the literature [1] to [20], the simulation of tapped
FC-TCR is not presented. In the present work, an attempt
is made to simulate Tapped FC-TCR system using
MATLAB Simulink software.
The FC-TCR System is shown in Fig. 1. Fixed capacitor
cannot produce variation in the reactive power .A
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R. V. D. Rama Rao & S. S. Dash
thyristor controlled reactor is connected in parallel with
the capacitor to produce variation in the reactive power.
Voltage and Current waveforms of TCR are shown in
Fig. 2.
performance is improved if the fixed capacitor is
substituted by an LC branch tuned to a value close to
the fundamental frequency of the network voltage .
Thyristors T1& T2 can select different inductance
values of the TCR, maintaining simultaneously high PF
and low THDI values. In fig. 3 L min is selected to limitthe
short circuit when the tags are reduced.The capacitor
across the load is for reactive power compensation. The
reactive power variation can not be obtained using fixed
capacitor. Thyristor controlled reactor is used to obtain
variation in the reactive power. Further variation can
be obtained by using tapped reactor system. Step
variation of inductance can be obtained using the M 1,
M 2 & M 3.
3. Simulation Results
Figure 1: FC-TCR Basic Circuit
Figure 2: TCR Waveforms
The thyristor current is as follows
R� � �
� �t
2V
i1 �
(sin(�t � �)) � sin (� � �)e L � � �
Z
Extinction angle bcan be obtained by the relation
sin (� � �) � sin (� � �) e
� R � � ��� �
� ��
�
� L �� � �
2. Tapped Inductor FC-TCR
Tapped inductor FC-TCR simulation circuit is shown in
Fig. 4. Pulses required by the IGBTs are generated using
the sources V2, V3, V4 & V5. The switches I1 to I4 produce
stepped variation in the current. Each choke is modeled
as a series combination of resistance & its inductance.
The input current waveform time in seconds and current
in amperes for x and y axis respectively is shown in Fig.
5, The switching pulses for M1 & M2 between time in
seconds and current in amperes for x and y axis
respectively are given in Fig. 6. The voltage across tapped
reactor between time in seconds and voltage in volts for
x and y axis respectively is shown in Fig. 7. The switching
pulses for the switches I1 to I4 are shown time in seconds
and current in amperes for x and y axis respectively in
Fig.8, at different instances the pulses are given to study
the variation of current. The current through TCR
between time in seconds and current in amperes for x
and y axis respectively is shown in Fig. 9. It can be seen
that inductance is cut out by closing the respective switch.
This increases the current in stepped manner. Output
current time in seconds and current in amperes for x and
y axis respectively and voltage waveforms time in
seconds and voltage in volts for x and y axis respectively
are shown in Figs. 10 & 11 respectively. The variation of
Active time in seconds and power in watts for x and y
axis respectively and Reactive power time in seconds
and power in kvar for x and y axis respectively is shown
in Fig. 12.
Basic TSR TCR circuit is shown in Fig. 3. when the
FC-TCR is supplied with a non-sinusoidal voltage, the
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I J E E S R, 3(1) June 2013
Enhancement of Power Quality using Tapped Inductor FC-TCR
Figure 3: The Basic FC-TCR Circuit
Figure 4: Simulink Circuit Diagram of FC-TCR
I J E E S R, 3(1) June 2013
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R. V. D. Rama Rao & S. S. Dash
Figure 5: Input Current
Figure 9: Current Through TCR
Figure 6: S1 & S2 Switching Pulses for TCR
Figure 10:Output Current
Figure 7: Voltage Across Tapped Reactors
Figure 11: Output Voltage
Figure 8: Switching Pulses for Controlled Reactors
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Figure 12:Active and Reactive Power
I J E E S R, 3(1) June 2013
Enhancement of Power Quality using Tapped Inductor FC-TCR
Conclusion
Reactive power compensation using Tapped inductor FCTCR was studied. Circuit model for tapped inductor FCTCR system was developed. It is used for simulation
studies using Matlab Simulink. The variation in reactive
power was smoother when using FC-TCR as compared
to Thyristor switched capacitors. The ability of this
system is that it can adjust the inductance to maintain
the power quality Thus the FC-TCR system is a viable
alternative to the thyristor switched capacitor bank. The
hardware is reduced since fixed capacitor does not require
any controlled switches. The value of THD for the input
current is reduced. The proposed tapped inductor system
does not introduce any switching transients. The analysis
and simulation results are presented. The simulation
results closely agree with the theoretical and analytical
values
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Figure 13:Experimental Circuit for FC-TCR
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Figure 14:Controlled Wave Forms
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