Chapter 6
Simulation results and analysis
129
CHAPTER 6
SIMULATION RESULTS AND ANALYSIS
6.1 INTRODUCTION
The MATLAB/Simulink simulation models of the proposed SHAF topology
for harmonic compensation in low and medium voltage power distribution systems
are discussed in chapters 4 and 5 respectively. The simulation results of LV test
system model are presented in section 6.2 and that of MV test system model are
presented and analysed in section 6.3 of this chapter.
In section 6.2, first the performance of the LV distribution system model
without any compensation is presented. Then, the LV test system performance with
shunt active filter compensation is presented followed by results of the LV test system
with proposed SHAF compensation for harmonic mitigation. The performance of
SAF and SHAF in reducing THDi is compared for low voltage test system. Using this
we are able to validate the effectiveness of the proposed SHAF compensation scheme.
In section 6.3 first the performance results of MV test system model without
any compensation are presented followed by the performance results of MV test
system with ACSLI based SAPF compensation and ACSLI based shunt hybrid active
power filter(SHAPF) compensation. The capability of the proposed ACSLISHAPF in
reducing THDI and improving power factor is evaluated. Finally, Total Harmonic
Distortion (THD) of source current with the proposed ACSLISHAPF and basic
ACSLISAPF are compared.
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Chapter 6
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130
6.2 RESULTS OF HARMONIC MITIGATION IN LV TEST
SYSTEM
In this section performance results of low voltage test system simulink model
without any compensation developed in section 4.2 are presented first followed by
results with SAF compensation along with its controllers developed in section 4.4 and
with proposed SHAF compensation developed in section 4.3.
6.2.1 Results of LV test System without any Compensation
The simulink model of LV test system without any compensation is developed
in chapter 4, section 4.2. It consists of a three-phase full-bridge diode rectifier load
connected to the distribution system in order to obtain the distorted load current. The
results of simulation are shown in Fig. 6.1 including three phase load current
waveforms, three phase source current waveforms and three phase source voltage
waveforms without any type of compensation.
6.1(a)
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Chapter 6
Simulation results and analysis
6.1(b)
6.1(c)
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131
Chapter 6
Simulation results and analysis
132
6.1(d)
Fig. 6.1 Results of LV test system without any compensation: (a) Non linear load current
for three phases (b) Source current for three phases (c) Three phase source
voltages (d) Phase angle comparison between source voltage and source current
for phase-a.
As can be seen, the resulting load current is highly distorted. It deviates
significantly from a sinusoidal waveform. This distorted load current leads to
distortion in the source currents and source voltage waveform as seen in Fig. 6.1(b)
and Fig. 6.1(c) respectively. The distortion in the source voltage waveforms is due to
the presence of source inductor (Ls) and distorted currents drawn by the load. The
source voltage and currents for phase-a are shown in Fig. 6.1(d) in which it is
observed that source current is out of phase with source voltage leading to poor power
factor due to reactive currents taken by the nonlinear load.
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Chapter 6
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133
6.2.2 Results of LV Test System with basic SAF Compensation
The basic configuration of SAF is shown in Fig. 6.2. The simulation results of
the basic shunt APF are shown in Fig. 6.3. When the SAPF is connected, the injected
compensation current (if) forces the source current (is) to become a near sinusoidal
waveform.
Fig. 6.2 SAPF Configuration.
Applying Kirchhoff’s Current Law (KCL) at the point of common coupling
(PCC), we get
is= iL- i f
(6.1)
where ‘is’ is the source current after compensation, ‘iL’ is the load current and ‘if’ is
the compensation current. The ideal current source is controlled to inject a
compensation current (if ) such that it cancels out the reactive and harmonic parts of
load current. In other words, reference value of if is equivalent to the summation of
iL,q and iL,h :
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Chapter 6
Simulation results and analysis
𝑖∗𝑓= iL,q+ iL,h
134
(6.2)
Simulation based on Eqn.(6.2) is carried out to verify the effectiveness of the
𝑖∗𝑓 under ideal compensation condition. Fig. 6.3 shows the simulation results of this
analysis. It is seen that the source current (is) waveform is obtained mathematically by
subtracting if from iL using Eqn.(6.1). Therefore the source current shown in Fig. 6.3
has very less harmonic content and also as seen from Fig. 6.4 the source current
waveform is in phase with the source voltage (vs) waveform, resulting in near unity
power factor.
Fig. 6.3 Simulation results of LV system with basic SAPF compensation -load current,
SAPF compensation current and source current waveforms for phase– a.
From Fig. 6.3 the source current contains appreciable amount of lower order
harmonics. This is due to the unavoidable switching ripple of the compensation
current, the presence of source inductor (Ls) and large amount of harmonics drawn by
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Chapter 6
Simulation results and analysis
135
Nonlinear load . When harmonic frequency switching ripple is injected into the point
of common coupling (PCC), it corrupts the source voltage, load current and source
current waveforms.
Fig. 6.4 Source voltage and source current for phase–a
(a)
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Chapter 6
Simulation results and analysis
136
(b)
Fig. 6.5 (a) Three phase SAF compensation currents and b) Three phase source currents
of SAF compensated LV test system model.
The three phase SAF compensating currents and source currents of the test
system with SAF compensation are shown in Fig. 6.5. It is seen that due to SAF
compensating currents the source currents attained near sinusoidal form. The
performance of SAF mainly depends on the technique used for estimating reference
signal for compensating currents. The synchronous reference frame theory
performance results and fuzzy logic based DC bus voltage controller results are
presented in the following sections.
 Results of Compensation Current Reference Estimation
Fig. 6.6 shows the estimated compensating reference currents in a-b-c
reference frame produced by d-q-0 theory based reference compensating current
estimator. As can be seen, the current waveforms are distorted. They deviate
significantly from sinusoidal waveform and resembles the harmonic content in the
source current. It can therefore be concluded that the application of d-q-0 theorem to
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Chapter 6
Simulation results and analysis
137
estimate the compensation current reference for the proposed SAF work very well.
Fig. 6.6. Compensation reference currents in a-b-c reference frame.
 Results of Fuzzy Logic based DC Bus Voltage Control
5000
4500
Capacitor voltage(Volts)
4000
3500
3000
2500
2000
1500
1000
500
0
0
0.5
1
Time (sec)
1.5
2
Fig. 6.7 DC bus capacitor voltage.
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Chapter 6
Simulation results and analysis
138
The DC bus capacitor voltage of SAF is shown in Fig. 6.7. From this Fig. 6.7,
it is seen that the DC bus capacitor voltage is maintained constant at reference value
of 4700V by using fuzzy logic controller. It has reached the steady state value after
0.5 sec.
6.2.3 Results
of
LV
System
Model
with
Proposed
SHAF
Compensation
Section 6.2.2 clearly demonstrated that the harmonic distortion in the source
current is reduced significantly by the use of basic shunt APF. However, an
appreciable amount of harmonic content still remains in the source current
waveforms. To reduce the dominant 5th and 7th order harmonics, tuned passive filter is
placed in parallel with the SAPF at the PCC in the proposed SHAF topology. The
TPF provides a path for 5th and 7th order harmonics. The MATLAB/Simulink model
of test system with the proposed SHAF topology is developed in Chapter 4, section
4.3.
Fig. 6.8 shows the simulation results of test system model with the proposed
SHAF compensation. When SHAF is applied, the injected compensation current (if)
forces the source current (is) to become near sinusoidal waveform and in phase with
the source voltage waveform, resulting in unity power factor. Comparing to the
simulation results with only SAPF as shown in Fig. 6.3, the harmonic content in the
source current is greatly reduced. It can be concluded that the TPF provides a path for
the 5th and 7th order harmonics to flow. This is evident by the fact that harmonic
content present in the TPF current waveform as seen in Fig. 6.8. Hence, the filtering
performance of SAPF is improved by the proposed SHAF topology.
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Chapter 6
Simulation results and analysis
139
Fig. 6.8 Non linear load current, SAF compensation current, TPF current and source
current for phase-a of LV test system with proposed SHAF compensation.
The three phase SAF currents, TPF currents and source currents of LV test
system with proposed SHAF compensation are shown in Fig. 6.9.
(a)
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Chapter 6
Simulation results and analysis
140
(b)
(c)
Fig. 6.9 Three phase a) SAF currents b) TPF currents and c) Source currents of SHAF
compensated LV test system.
From Fig. 6.9. it is seen that due to compensation action of SAF current and
TPF current the source current reached near pure sinusoidal wave form.
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Simulation results and analysis
141
Fig. 6.10 LV test system source voltage and source current comparison for phase-a with
SHAF compensation.
The Fig. 6.10 shows LV test system source voltage and current for phase-a
with proposed SHAF compensation. From the Fig. 6.10 it is seen the source voltage is
in phase with source current leading to unity power factor. Thus the performance of
proposed SHAF topology is superior to that of SAF compensation in improving
power factor. This is evident by comparing Fig. 6.4 and Fig. 6.10.
6.2.4 Harmonic Distortion Analysis for LV Test System
The THD is the most common indicator to determine the quality of AC
waveforms. Using the Fast Fourier Transform (FFT), the harmonic spectrum of the
source current under different compensation conditions are presented. Then, the THD
comparison is carried out for the simulation results. The harmonic spectrum of the
source current of LV test system without compensation is shown in Fig. 6.11. From
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Chapter 6
Simulation results and analysis
142
the spectra plot, it can be seen that the source current contains large amount of
harmonic current components of frequencies below 1 kHz and the THDi is 12.4%.
Fig. 6.11 Harmonic spectrum of phase-a load current of LV test system without any
compensation.
The Harmonic spectrum of the three phase source current with basic SAPF
compensation is shown in Fig. 6.12 for all three phases-a,b,c.
(a)
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Chapter 6
Simulation results and analysis
143
(b)
(c)
Fig. 6.12 Harmonic spectrum of source current with basic SAPF compensation
(a) Phase-a (b) Phase-b (c) Phase-c.
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Chapter 6
Simulation results and analysis
144
From Fig. 6.12 it is seen that the basic shunt APF successfully filters the
harmonic current components caused by the nonlinear load. This is evident by the
reduction of source current THD from 12.4% to nearly 2%, but still there are some
low order harmonics present in the source current harmonic spectrum.
Fig. 6.13 shows the harmonic spectrum of the source current with the
proposed SHAF compensation. It is seen that the THDI is reduced to 1.62%. In
comparison to Fig. 6.12, the source current harmonic spectrum is almost free of
harmonic components. This implies that the proposed SHAF compensates the
distorted source currents including dominant 5th and 7th order harmonics. The source
current THD comparison is carried for different compensations in Table 6.1.
(a)
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Chapter 6
Simulation results and analysis
145
(b)
(c)
Fig. 6.13 Harmonic spectrum of source current of LV test system with proposed SHAF
compensation (a) Phase-a (b) Phase-b (c) Phase-c.
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Simulation results and analysis
146
Table 6.1 THD comparison of source current of LV test system for different
compensations.
THDI (%)
Type of compensation
Without compensation
With basic SAF Compensation
With proposed SHAF compensation
Isa
Isb
Isc
12.4
12.4
12.4
2
1.86
1.95
1.62
1.39
1.52
The source current THD is reduced from 12.4 % to 2 % with basic shunt APF.
With the proposed SHAF, the source current THD is further reduced to 1.62 %. Thus,
the harmonic filtering performance of the proposed SHAF topology is superior
compared to the basic shunt APF which is well below the harmonic limit imposed by
IEEE Standard 519.
6.3 RESULTS OF HARMONIC MITIGATION IN MV TEST
SYSTEM
This section presents the simulation results of the simulink model of the
proposed 7-level SHAF for harmonic mitigation in a MV distribution system
developed in chapter 5. It presents the simulation results of MV test system model
without any compensation in section 6.3.1 first, followed by the results of MV test
system with basic seven level SAPF in section 6.3.2 , followed by the results of MV
system with proposed 7-level SHAPF compensation in section 6.3.3. The Results of
performance of ACSLSAF are presented and analysed and then compared with the
results of the proposed ACSLSHAPF for mitigating harmonics in medium voltage test
system.
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Chapter 6
Simulation results and analysis
6.3.1 Results of MV Test System without any Compensation
(a)
(b)
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147
Chapter 6
Simulation results and analysis
148
(c)
(d)
Fig. 6.14 Simulation results of MV test system without compensation a) Three phase
nonlinear load currents
source voltages
b) Three phase source currents c) Three phase
d) Phase angle comparison between source voltage and
source current for phase-a.
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Chapter 6
Simulation results and analysis
149
The simulink model of medium voltage test system developed in chapter 5,
section 5.2 consists of a three-phase full-bridge diode rectifier load connected to a
three phase distribution source of voltage 4.5 kV(peak) in order to obtain the distorted
load current. Fig. 6.14 shows the simulation results of MV test system without any
compensation .
It shows three phase Load currents, source currents, source voltages, and
phase angle comparison between source voltage and source current waveforms of
phase-a. As can be seen, the resulting load current is highly distorted and deviated
significantly from sinusoidal waveform. This distorted load current leads to distortion
in the source current and source voltage waveforms. The distortion in the source
voltage waveform is due to the presence of source inductor (Ls) and distorted currents
drawn by the load. The source voltage and source current for phase-a are shown in
Fig. 6.14(d) in which it is seen that source current is out of phase with source voltage
leading to poor power factor.
6.3.2 Results of MV Test System with basic 7-Level SAPF
Compensation
This section presents the simulation results of MV test system model with
basic seven level SAPF compensation developed in Chapter 5, section 5.3. The
Fig. 6.15 shows the single phase and three phase seven level output voltage wave
forms of asymmetric cascaded inverter based SAPF.
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Simulation results and analysis
150
(a)
(b)
Fig. 6.15 Seven level voltages generated by the asymmetric cascaded inverter for
(a) Phase-a (b) Phases a, b and c.
From this Fig. 6.15, it is evident that the reference current estimator and
CSFMCSH PWM method are worked satisfactorily and produced required gating
signals for asymmetric cascaded seven level inverter to generate required seven level
output voltage. The three phase compensating currents injected by ACSLI SAPF for
harmonic mitigation and three phase source currents after ACSLISAPF compensation
are shown in Fig. 6.16.
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Chapter 6
Simulation results and analysis
151
(a)
(b)
Fig. 6.16. (a)Three phase ACSLISAPF currents and (b) Three phase source currents
with ACSLI based SAPF compensation for MV test system.
From this Fig. 6.16, it is seen that the harmonic content in the source current is
very much reduced with SLI SAPF compensation and the wave form attained near
sinusoidal form compared to source current waveform without any compensation in
Fig. 6.14(b). The source current THD is also reduced from 12.4% to 3.51 % from
THD analysis given in section 6.3.4. For ease of comparison the load current, SAPF
compensating current and source currents for phase-a only are shown in Fig. 6.17,
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Chapter 6
Simulation results and analysis
152
when the MV test system is compensated with basic ACSLI based SAPF.
Fig. 6.17 Load current, filter current and source current for phase- a of MV test system
with ACSLI based SAPF compensation.
From the Fig. 6.17, it is observed that the load current is heavily distorted in
phase–a and the ACSLI based SAPF has injected suitable harmonic current to
compensate the load harmonics and hence the source current is almost pure
sinusoidal. Also the filter current is injected at the PCC such that source current is
sinusoidal and it is forced to be in phase with the voltage at the AC mains after
compensation of ACSLI based APF, leading to near unity power factor which is
evident from the Fig. 6.18.
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Chapter 6
Simulation results and analysis
153
Fig. 6.18 Phase angle comparison between source voltage and source current for
phase–a after compensation with ACSLISAF.
The performance of SAF mainly depends on the technique used for estimating
reference signal for compensating currents and the method adopted to generate gating
signals for voltage source inverter. The results of synchronous reference frame d-q
theory, fuzzy logic based DC bus voltage controller and CSFSHPWM are presented
in the following sections.
 Results of d-q-0 Theory in SLISAPF compensation
In this section, the results of d-q theory based reference compensating current
estimator model are presented. Fig. 6.19 shows the estimated compensating reference
currents produced by d-q-0 theory estimator model in a-b-c reference frame. As can
be seen from Fig. 6.19(a) the estimated compensation current waveforms are distorted
showing the harmonic content in the load current. Figure 6.19(b) shows the reference
three phase current wave forms for PWM after subtracting with actual compensating
currents.
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Chapter 6
Simulation results and analysis
154
(a)
(b)
Fig. 6.19 (a) Compensation reference currents in a-b-c reference frame and b) Three
phase modulating signals for CSFSHPWM for ACSLISAPF compensation.
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Chapter 6
Simulation results and analysis
155
It can therefore be concluded that the application of d-q theorem to estimate
the compensation current reference for the proposed SAPF work very well.
 Results of Fuzzy Logic based DC Bus Voltage Control
Fig. 6.20 DC bus capacitor voltage on LV cell.
The DC bus capacitor voltage is controlled by using fuzzy logic controller on
the LV cell of ACSLI as explained in section 5.3.2. The Fig. 6.20 shows the DC bus
capacitor voltage on LV cell. It is noted that the Fuzzy Logic Controller maintained
1.5 kV (LV cell) capacitor voltage constant.
 Results of CSFSHPWM
The switching devices of each phase leg of ACSLI are controlled by
CSFSHPWM model developed in section 5.3.2 in which triangular carrier signals are
compared with reference sinusoidal signal generated by reference current estimator. A
small section of the adopted carrier signals and modulating signal for controlling two
H-bridges of phase-a of ACSLI are shown in Fig. 6.21 and the generated gating
signals are shown in Fig. 6.22.
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Chapter 6
Simulation results and analysis
Fig. 6.21 Carrier signals and reference signal for phase-a of CSFSHPWM.
Fig. 6.22 A small section of the gating signals for phase–a of ACSLI.
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156
Chapter 6
Simulation results and analysis
157
6.3.3 Results of MV Test System with proposed ACSLI based SHAPF
Compensation
This section presents the simulation results of the proposed ACSLI based
SHAPF compensated medium voltage system simulink model developed in chapter 5,
section 5.3. The nonlinear current load current is compensated using a three-phase
ACSLI based SHAF associated with d-q theory for compensating reference current
estimation and CSFMCSHPWM for generating gating signals.
 Results of D-Q Theory Based Compensating Current Reference
Estimator in ACSLISHAPF Compensation
The reference currents estimated by d-q-0 theory based reference current
estimator in a-b-c reference frame are shown in Fig. 6.23.
Fig. 6.23 The reference compensating currents in a-b-c reference frame for ACSLI
based SHAPF compensation.
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Chapter 6
Simulation results and analysis
158
It is seen that the peak value of reference currents are less in this case
compared to reference currents in SAPF compensation shown in Fig. 6.19(a). This is
due to the absorption of 5th and 7th harmonic currents by the TPF connected in parallel
with the load in addition to SAPF in this hybrid filter. This is observed in a-b-creference frame currents which proves the effectiveness of reference compensating
current estimator in evaluating the harmonic content in the load current.
 Results of CSFSHPWM in ACSLISHAPF Compensation
The Fig. 6.24 shows the modulating signal generated and the triangular carrier
signals for phase–a in this topology.
Fig. 6.24 Modulating signal and the triangular carrier signals of CSFSHPWM of
phase–a in SHAPF compensation.
The seven level single phase and three phase output voltages of ACSLI in
SHAPF topology is shown in Fig. 6.25. It is seen that the seven level output voltage is
not disturbed due to the addition of TPF in ACSLI based SAPF model.
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Chapter 6
Simulation results and analysis
159
.
(a)
(b)
Fig. 6.25 Output voltage of ACSLI based SAF for a) Phase-a b) Three phases.
The three phase compensating currents injected by ACSLI based SAPF in
SHAPF topology is shown in Fig. 6.26 and the three phase TPF currents are shown in
Fig. 6.27. Due to these harmonic compensating currents the source current is free
from harmonics and is as shown in Fig. 6.28.
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Chapter 6
Simulation results and analysis
160
Fig. 6.26 Compensating three phase currents of ACSLI based SAF in SHAF topology.
Fig. 6.27 Three phase tuned passive filter currents in ACSLISHAF topology.
Fig. 6.28 Three phase source current of MV test system with ACSLI based SHAPF
compensation.
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Chapter 6
Simulation results and analysis
161
For the ease of comparison the load current, SAPF current, TPF current and
source current for phase-a are given Fig. 6.29.
Fig. 6.29 Load current, ACSLI based SAF current, tuned passive filter current and
source current for phase- a with ACSLI based SHAF compensation.
From the Fig. 6.29, it is seen that the combination of SAF current and tuned
passive filter current effectively compensated for the harmonics in the load current
and reduced the THD in source current from 12.4% to1.01% as presented in section
6.3.4.
6.3.4 Harmonic Distortion Analysis for MV Test System
In this section the harmonic spectrum of the source current using the FFT
under different compensation conditions are presented. Then, the THD comparison is
carried out for the simulation results. The spectrum of the source current without
compensation is shown in Fig. 6.30 for phase-a. From the spectra plot, it can be seen
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Chapter 6
Simulation results and analysis
162
that the source current contains large amount of harmonic current components of
frequencies below 1 kHz and the THD in source current is 12.4%. It is seen that the
most dominant are 5th and 7th order harmonics in the spectra plot.
Fig.6.30 Harmonic spectrum of phase–a source current of MV test system without any
compensation.
The spectrum of three phase source currents of MV test system with basic
ACSLISAPF compensation is shown in Fig. 6.31. The ACSLISAPF successfully
filtered the harmonic current components caused by the nonlinear load.
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Chapter 6
Simulation results and analysis
(a)
(b)
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Chapter 6
Simulation results and analysis
164
(c)
Fig. 6.31 Harmonic spectra of source currents of MV test system with ACSLISAPF
compensation a) For phase–a b) For phase-b and c) For phase-c.
Although the high frequency harmonic components (i.e. greater than 1 kHz)
are filtered significantly, appreciable amount of lower order harmonics still remain in
the source current spectrum. The most dominant are 5th and 7th order harmonics. To
eliminate these harmonics shunt tuned passive filters are connected in addition to
ACSLISAPF in the proposed hybrid filter. The source current harmonic spectrum of
MV test system with the proposed ACSLSHAPF compensation is shown in Fig. 6.32.
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Chapter 6
Simulation results and analysis
(a)
(b)
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165
Chapter 6
Simulation results and analysis
166
(c)
Fig. 6.32 Source current harmonic spectra of MV test system with ACSLISHAPF
compensation a) For phase –a b) For phase-b and c) For phase-c
From the Fig. 6.32, it is seen that the proposed ACSLISHAPF reduces the
THD in nonlinear load current well below the limit specified by IEEE. This implies
that the proposed hybrid APF effectively compensates the load current harmonics.
The source current THD is reduced from 12.4 % to 3.51 % with ACSLISAPF and
with the proposed ACSLISHAPF, the source current THD is further reduced to 1.01
%. Thus, the harmonic filtering performance of the proposed ACSLISHAF topology
is superior compared to the ACSLISAPF which is well below the harmonic limit
imposed by IEEE Standard 519. The source current THD comparison is carried out
for ACSLISAPF and ACSLISHAPF compensations in Table 6.2.
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Chapter 6
Simulation results and analysis
167
Table 6.2 THD comparison of source current of MV system for different compensations.
THD (%)
Isa
Isb
Isc
Without compensation
12.4
12.4
12.4
With ACSLISAPF Compensation
3.51
3.28
3.44
With proposed ACSLISHAPF
1.01
1.29
1.25
Type of compensation
compensation
6.3.5 Response of proposed ACSLI based SHAPF for 3-phase Fault
To test the ability and flexibility of the proposed three-phase ACSLI based
SHAPF configuration in compensating the current harmonics under dynamic
conditions a three phase fault is introduced at time 0.04s and cleared at time 0.072s in
the MV system model developed in chapter 5, section 5.4. The Fig. 6.33 shows the
load current, filter compensating current and source currents of ACSLISHAF
compensated test system with three phase fault.
Ph.D Thesis submitted to Jawaharlal Nehru Technological University Anantapur, Anantapur.
Chapter 6
Simulation results and analysis
(a)
(b)
Ph.D Thesis submitted to Jawaharlal Nehru Technological University Anantapur, Anantapur.
168
Chapter 6
Simulation results and analysis
169
(c)
Fig. 6.33 Three phase (a) Load Currents and b) Compensating currents and (c) Source
currents of ACSLISHAF compensated test system for three phase fault.
From the Fig. 6.33, it is seen that the distortion in source current is very less
compared to that of load current due to the presence of ACSLISHAPF compensation.
From the results the proposed ACSLI based SHAPF is capable of compensating
harmonics at the time of faults under dynamic conditions.
6.4 CONCLUSION
This chapter presented the results obtained from the simulations of SHAF
compensated LV test system and MV test system. Simulation and tests were
conducted aiming to illustrate the effectiveness of the proposed shunt hybrid APF in
harmonic mitigation in low voltage test system. The effectiveness of d-q theory in
estimating compensation reference current is demonstrated. In addition, the
Ph.D Thesis submitted to Jawaharlal Nehru Technological University Anantapur, Anantapur.
Chapter 6
Simulation results and analysis
170
effectiveness of fuzzy logic controller in maintaining DC bus voltage is discussed.
The simulation results are analysed and discussed. Finally, a detailed THD analysis on
source current spectrums is carried out to validate the harmonic filtering performance
of the proposed SHAPF topology in comparison to the basic SAPF compensation in
LV system.
The results of the proposed three-phase ACSLI based SHAPF shown that it
has compensated the distortion in the line current caused by nonlinear load in a
medium voltage distribution system. Based on the results, the proposed SHAPF
topology is capable of responding effectively to the harmonics caused by the threephase diode rectifier load. The total harmonic distortion of the source current without
compensation is high; about 12.4 % in each phase and THDi with SLI based SAPF is
3.51%. When compensation is made with the proposed ACSLISHAPF, the total
harmonic distortion is reduced to 1.01%, which is fairly good. Thus ACSLISHAPF
performance is superior compared to SLI based SAPF and has better response under
dynamic conditions.
Ph.D Thesis submitted to Jawaharlal Nehru Technological University Anantapur, Anantapur.