Control Design For Shunt Active Power Filter Based On p-q Theory In Photovoltaic Grid-Connected System

International Journal of Power Electronics and Drive System (IJPEDS)
Vol. 9, No. 3, September 2018, pp. 1064~1071
ISSN: 2088-8694, DOI: 10.11591/ijpeds.v9.i3.pp1064-1071  1064
Journal homepage: http://iaescore.com/journals/index.php/IJPEDS
Control Design for Shunt Active Power Filter Based on
p-q Theory in Photovoltaic Grid-Connected System
Moh. Jauhari1
, Dedet Candra Riawan2
, Mochamad Ashari3
1
Department of Industrial Electric Engineering, Politeknik Negeri Madura (Poltera), Indonesia
2,3
Department of Electrical Engineering, Institut Teknologi Sepuluh Nopember (ITS) Surabaya, Indonesia
Article Info ABSTRACT
Article history:
Received Jan 30, 2018
Revised Jul 23, 2018
Accepted Aug 6, 2018
This paper presents the control for Shunt Active Power (SAPF) filter in
photovoltaic (PV) systems connected to the grid. The proposed configuration
of the system consists of a photovoltaic array that connected to the grid
through the three-phase inverter topology that also serves as an active filter.
Photovoltaic is coupled in parallel with the direct curret (DC) side of the
active filter. With this configuration, can be obtained three advantages,
namely the elimination of harmonic currents caused by nonlinear load,
reactive power injection, and injection of active power generated
photovoltaic. The p-q Theory is used to calculate the harmonic reference
current to be used to control the active filter coupled fotovoltaic in generating
anti-harmonic currents. The results show that system can reduce harmonic
distortion from THD 27.22% to be THD 1.05%, whereas when the active
power from photovoltaic injected, the THD become 2.01%. Power sharing
can also be seen from this study.
Keyword:
Photovoltaic
p-q Theory
Reference current
SAPF
THD
Copyright © 2018 Institute of Advanced Engineering and Science.
All rights reserved.
Corresponding Author:
Moh. Jauhari,
Departement of Industrial Electric Engineering,
Politeknik Negeri Madura,
Jl. Raya Camplong km. 4, Taddan, Camplong, Sampang, East Java, Indonesia.
Email: mohjauhari51@gmail.com
1. INTRODUCTION
The development of power electronics equipment that used as an interface between the load and the
electrical system affects the power quality in particular the emergence of electrical harmonics [1]. the power
electronics converter is a nonlinear load that injects the harmonic current on the grid. the non linear load is
the main cause of harmonic distortion that occurs in the electrical system. Variable Speed Drives (VSD),
Uninterruptible Power Supply (UPS), Switched Mode Power Supply (SMPS) [2].
Harmonic distortion causes some unexpected conditions on the electrical system. Harmonic
distortion can decrease the accuracy of the electrical meter. Harmonic distortion may also cause excessive
dissipation of electrical equipment so as to increase the cost of the bill. Furthermore, harmonic distortion
causes electrical equipment not to work on the specified power quality standards causing a decrease in the
lifetime of the electrical equipment [3].
Passive filter is one method used to reduce current harmonic distortion. These passive filters use a
combination of inductors and capacitors to eliminate harmonics at a predetermined frequency. The drawback
of this is a passive filter harmonic compensation provided is fixed, so it can not eliminate the frequency
harmonics that are not specified [4]. Active Power Filter (APF) has advantages that can eliminate various
frequency harmonics that arise. In active power filter, there are an inverter and controllers to control the
compensation current to eliminate the harmonic currents distortion that arise [5]-[6]. Shunt active power filter
(SAPF) arranged in parallel with the non-nilier load. The shunt active power filter has advantages in
dimension than in series type [7].

Int J Pow Elec & Dri Syst ISSN: 2088-8694 
Control Design for Shunt Active Power Filter Based on p-q Theory in... (Moh. Jauhari)
1065
The p-q Theory introduced by Professor Akagi in 1983 [8]. This Theory explains the concept of
active and reactive power in the instantaneous calculation algorithm. Than, the p-q Theory developed in the
application of power flow calculations and harmonic distorted component calculations to determine the
reference current [9]-[11].
The generation of reference current of active power filter influenced by the performance of active
power filter control system in response to the load changes. Closed-loop control proportional-integral (PI) is
used to regulate DC side voltage and power flow of active power filter [12]-[14]. The use of closed-loop
control systems improve the accuracy of p-q Theory in the generation of the reference current in the range of
larger currents.
Research and development of photovoltaic grid-connected systems has increased very significantly
in the last two centuries. Three-phase inverter Sinusoidal Pulse width modulation (SPWM) control system
used to transfer active power that generated by photovoltaic into the grid [15]-[18].
This paper, photovoltaic coupled in parallel with the shunt active power filter so that with this
system, the shunt active power filter not only can reduce harmonic currents but also can supply the active
power that generated by photovoltaic. P-q theory is used to control active power filters in determining
harmonic reference currents.
The contribution of this paper is to combine the functions of an active power filter into the
photovoltaic grid-connected systems so that by the proposed design system, it will be obtained three
advantages, namely harmonic current compensation, reactive power compensation, and the of active power
compensation that generated by photovoltaic. Basic p-q Theory is modified to perform the function of active
power compensation. Photovoltaic array voltage is increased by using quadratic boost converter with a
voltage conversion ratio is relatively larger than conventional boost converter.
2. SYSTEM DESIGN
2.1. Shunt Active Power Filter In Photovoltaic Grid-Connected System
The active power filter design on Photovoltaic Grid-Connected System consists of two main
components, namely the shunt active power filter which are arranged in parallel with a nonlinear load, and
photovoltaic that arranged in parallel with the DC side voltage of the Voltage Source Inverter (VSI). Active
power filter serves to eliminate harmonics at the source based on the control system that used. In addition, the
active filter also serves to compensate for reactive power into the load [19]. Active power filter coupled
photovoltaic can inject active power to be supplied into the grid. Notation SAPF+PV show shunt active filter
system coupled photovoltaic.
Figure 1 shows the configuration of the filter active in photovoltaic grid-connected system. Active
power filters coupled photovoltaic connected to the distribution network through a Point of Common
Coupling (PCC) through the LF inductor. The LF Inductor is not as inductor for passive filter but as an
inductor coupling that serves as a filter switching VSI [20].
The DC voltage at the photovoltaic array is connected to the DC-DC to obtain high DC voltage
[21]-[22]. Quadratic converter is used as a DC-DC converter because the ratio of input and output voltages
are relatively large [23]. The layout of inductors, capacitors, diodes, and switch on quadratic boost converter
as shown in Figure 2. Correlation of the input and output voltage of quadratic boost converter as in the
following Equation (1):
vout
vin
=
1
(1−D)2 (1)
where D is the duty cycle.
Figure 1. Effects of selecting different switching under dynamic condition

 ISSN: 2088-8694
Int J Pow Elec & Dri Syst, Vol. 9, No. 3, September 2018 : 1064 – 1071
1066
Figure 2. Quadratic converter topology
2.2. Control System On The Shunt Active Power Filter Coupled Photovoltaic
The p-q Theory is used to calculate the reference current of shunt active power filter. Reference
current is a signal current waveform of the anti-harmonics current. Than, the Reference current is used to
control the switching pattern of shunt active power filter so that anti-harmonic current can be generated.
Anti-harmonic current waveform is used to eliminate the harmonic current waveform.
The first step in the calculation of the reference current generation is to transform the three-phase
voltages and currents in abc coordinates into two phases in αβ coordinates using clarke transformation. This
transformation is necessary to simplify the calculation of instantaneous power at a later stage [24]. Equation
(2) shows the Clarke transformation of voltage while equation (3) shows the current clarke transformation.
[
vα
vβ
] = √
2
3
[
1
−1
2
−1
2
0
√3
2
√3
2
] [
va
vb
vc
] (2)
[
Iα
Iβ
] = √
2
3
[
1
−1
2
−1
2
0
√3
2
√3
2
] [
Ia
Ib
Ic
] (3)
Based on the p-q Theory, instantaneous active and reactive power can be expressed in a
multiplication operation voltages and currents in the αβ coordinates as in Equation (4).
[
p
q] = [
vα vβ
-vβ
vα
] [
Iα
Iβ
] (4)
Instantaneous power p and q in equation (4) consists of the AC component (p~ and q~) and the DC
component (P and Q). DC components are fundamental components while the AC component is a harmonic
component, so that:
[
p
q] = [
P + p~
Q + q~
] (5)
To calculate the current value of the equation (4), the equation is reversed, so that would be
obtained:
[
Iα
Iβ
] =
1
vα
2+ vβ
2 [
vα -vβ
vβ vα
] [
p
q] (6)
Figure 3 shows the calculation step of p-q Theory in generating a reference current signal. The
voltage and current on the source side is read by the sensor is then used as input for the calculation of the
reference current generation. The reference current is then compared with the current compensation of active
power filter using hysteris current control method to produce a switching pattern on the VSI of active power
filter.
From Equation (5) and Equation (6) can be seen that for eliminating reactive power from the source
is to making negative value of q in equation (6). To separate the harmonic component to the fundamental
component, p power only use the AC components. Then the PPV power of the photovoltaic added. Power
losses in the VSI is represented as Ploss. so that the reference current is:

1067
[
Icα*
Icβ*
] =
1
vα
2+ vβ
2 [
vα -vβ
vβ vα
] [
p~ − Ploss + PPV
-q
] (7)
Figure 3. Block diagram of p-q Theory calculation
Reference current in Equation (7) is then transformed from the αβ coordinates into abc coordinate
with Equation (8):
[
Ica*
Icb*
Icc*
] = √
2
3
[
1 0
−1
2
√3
2
−1
2
−√3
2 ]
[
Icα*
Icβ*
] (8)
2.3. Parameter
Table 1 shows the parameters that used in the simulation of shunt active power filter in the active
filter in photovoltaic grid-connected system.
Table 1. The Parameter Value of Shunt Active Power Filter Coupled Photovoltaic
Parameters Value
VSource 3ϕ 380 volt
frequency 50 Hz
Load 6-pulsa rectifier 1700 watt, 10 var
VDC 850 volt
DC-link capacitor 20 uF
LF Inductor 55 mH
PPV 250 watt
PI constans Kp=10, K1=15
Converter component L1=25 μH, L2=150 μH,
C1=68,544 μF, C2=52,735 μF
3. RESULT AND ANALYSIS
SAPF+PV system configuration as shown in Figure 2 is simulated with MATLAB / Simulink to
determine the performance of the system. Time sampling is 0.000006s. The scenario which was performed
during the simulation includes, power flows from the source, PV and load. Simulations time line performed
during 0.2s. For the firs 0.1s, the system is operated as pure SAPF then for the next second power from PV is
injected.
3.1. Active Power And Reactive Power Of Shunt Active Power Filter In Photovoltaic Grid-Connected
System
Shunt active power filter coupled photovotaic actively controlled in order to supply the active and
reactive power to the load or to the grid. Simulations conducted under a constant load 1700 watts and 210

 ISSN: 2088-8694
1068
var. The system serves as a pure SAPF at t=0.02s until t=0.1s, during this period, all of the needs of active
power served by the source. Then in the period t=0.1s to t=0.2s, photovoltaic power is injected so that the
needs of active power is supplied by photovoltaic. As for the reactive power, all the needs of the load served
by the shunt active power filter. Figure 4 and Figure 5 respectively show the relationship between the active
and reactive power of source, load, and SAPF+PV. The simulation results show that the SAPF+PV systems
are already able to control the power flow of active and reactive power.
Figure 4. Active power curve of source, load and
SAPF+PV
Figure 5. Reactive power curve of source, load and
SAPF+PV
3.2. The Dc Side Voltage Of Of Shunt Active Power Filter In Photovoltaic Grid-Connected System
In accordance with the design, the DC side voltage is kept constant at a reference voltage of 850
volts. Figure 6 shows the DC side voltage can be kept constant according to the voltage reference despite the
process of photovoltaic power injection at t=0.1 s. it indicates that the DC side voltage regulator is already
working optimally.
Figure 6. The DC side voltage of SAPF+PV
3.3. Shunt Active Power Filter Simulation In Photovoltaic Grid-Connected System
Figure 7 shows the simulation results of the shunt active power filter active in photovoltaic grid-
connected system. The voltage that used in the calculation of the reference current is the voltage of each
phase. compensation results show that the current resources has been a pure sinusoidal. In addition, the
compensation current waveform is different at the time of photovoltaic injected active power into the grid.
0.04
0.02 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2
0
-500
Active
Power
(watt)
1500
1000
Time (s)
SAPF+PV
Source
Load
0
500
2000
2500
-1000
0.04
0.02 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2
0
0
Reactive
Power
(var)
200
150
Time (s)
SAPF+PV
Source
Load
50
100
250
300
0.04
0.02 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2
0
Time(s)
1000
800
600
400
200
0
Vdc
(V)
-200

1069
Figure 7. Simulation results of the shunt active power filter active in photovoltaic grid-connected system
In this study, analysis of harmonic component content is done by using Fast Fourier Trasform (FFT)
Analysis with the maximum frequency that used in the calculation of Total Hamonic Distorsion (THD) is
1000 Hz. The magnitude of the fundamental component and harmonic components expressed in percent
units. The magnitude of the first order or the fundamental frequency would be 100%, which is the largest
magnitude, whereas in the other order will be smaller than the first order. Figure 8-10 shows the harmonic
spectrum in the time before and after compensated.
Figure 8. THD of current source before compensated
Figure 9. THD of current source before compensated in pure SAPF mode
Figure 10. THD of current source before compensated in SAPF+PV mode
0.04
0.02 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2
0
0.04
0.02 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2
0
0.04
0.02 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2
0
0.04
0.02 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2
0
Time (s)
-5
5
0
Isabc
(A)
-4
4
0
ILabc
(A)
-2
2
0
Ica
(A)
400
0
Vabc
(V)
-400

 ISSN: 2088-8694
1070
From the simulation results, the THD of current source before compensated is 27.22% as shown in
Figure 8. Meanwhile, after the compensated, the THD of current source is 1.05% when the system is
operating as a pure SAPF as shown in Figure 9. When SAPF coupled with PV, the THD of current source is
2.01% as shown in Figure 10.
4. CONCLUSION
In this paper, the design of shunt active power filter based on p-q Theory in photovoltaic grid-
connected system has been proposed. The p-q Theory is used to calculate the reference current. From the
simulation results, can be obtained some key points as follows:
a Vdc voltage can be kept constant corresponding reference voltage of 850 Volt.
b Control of active and reactive power flow can work according to the p-q Theory.
c SAPF+PV systems are designed to reduce the value of THD that generated by 6-pulse rectifier 1700
Watt from 27.22% to 1.05%. While, when the active power from photovoltaic is injected, the THD
becomes 2.01%.
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BIOGRAPHIES OF AUTHORS
Moh. Jauhari received bachelor of Engineering (Electrical) from Institut Teknologi Sepuluh
Nopember (ITS) Surabaya, Indonesia In 2015. In 2017, he received his Master degree from ITS,
He joined POLTERA as lecturer in 2017.
Email: mohjauhari51@gmail.com
Dedet Candra Riawan received the Bachelor Degree in Electrical Engineering from Sepuluh
Nopember Institute of Technology (ITS), Indonesia in 1999 and joined ITS as lecturer in 2000.
He received his PhD, and Master Engineering degree from Curtin University of Technology,
Australia, in 2006 and 2010 respectively. His interest of research is in power electronics and its
application in renewable energy.
Email: dedet.riawan@ee.its.ac.id
Mochamad Ashari recieved his bachelor degree from Institut Teknologi Sepuluh Nopember
(ITS) Surabaya, Indonesia in 1989 and joined ITS as lecturer in 1990. In 1998 and 2001, he
received his Master and PhD. degrees from Curtin University, Australia. He became Professor to
the Department in 2009. His research interests include applications of power electronics for grid
systems, power quality, and renewable energy. He has received research grants from many
institutions including ABB, JICA-Japan, Indonesia government.
Email : ashari@ee.its.ac.id

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