ArticlePDF Available

Combined operation of photovoltaic and active power filter system connected to nonlinear load

  • Université frères Mentouri Constantine 1

Abstract and Figures

Currently, photovoltaic inverters are used in electricity production. They must therefore meet the requirements and needs of the electricity grid. They are not only used to provide active and reactive power, but also contribute to other tasks such as power quality, frequency and voltage regulation. This paper presents a photovoltaic system connected to the grid via an inverter combined with a parallel active filter. The model aims to provide active power to the grid as well as reactive power with a higher power quality. Thus, this model can compensate for harmonics caused by the grid or non-linear loads. The command of this model requires a robust and reliable control system to perform the three above-mentioned tasks (quality, frequency and voltage regulation). Consequently, the instantaneous power method was chosen for this model. This system was simulated in the Matlab/Simulink program to validate its function. Key words: Photovoltaic system (PV), Active power filter (APF), Grid connected, Instantaneous power theory, Maximum power point tracking (MMPT).
Content may be subject to copyright.
Roum. Sci. Techn.– Électrotechn. et Énerg.
Vol. 64, 4, pp. 371–376, Bucarest, 2019
1Faculty of Technology Sciences, Frères Mentouri-Constantine 1 University, Algeria
2Institute of Electrical Engineering and Computer Science, Silesian University of Technology, Poland
* Correspondent author:
Key words: Photovoltaic system (PV), Active power filter (APF), Grid connected, Instantaneous power theory, Maximum power
point tracking (MMPT).
Currently, photovoltaic inverters are used in electricity production. They must therefore meet the requirements and needs of the
electricity grid. They are not only used to provide active and reactive power, but also contribute to other tasks such as power
quality, frequency and voltage regulation. This paper presents a photovoltaic system connected to the grid via an inverter
combined with a parallel active filter. The model aims to provide active power to the grid as well as reactive power with a higher
power quality. Thus, this model can compensate for harmonics caused by the grid or non-linear loads. The command of this
model requires a robust and reliable control system to perform the three above-mentioned tasks (quality, frequency and voltage
regulation). Consequently, the instantaneous power method was chosen for this model. This system was simulated in the
Matlab/Simulink program to validate its function.
In recent years, renewable energy sources (RES) have
required more auxiliary services on the grid such as
conventional power stations. In addition, these renewable
energy sources must provide clean energy to the grid with
minimum total harmonic distortion (THD).
Photovoltaic power plants are currently being developed
in global electricity generation through the development of
solar panels and PV inverters for the main equipment [1].
Unfortunately, photovoltaic systems only operate during the
day and they are switched off during the night. Therefore,
they will not provide continuous active power to the grid
and their availability rate is low compared to the
conventional power plant [2].
Several studies [3–26] have been carried out to improve
the quality of the PV energy system. These studies are
based on the combination of an active filter with
photovoltaic systems to inject active power with low levels
of total harmonic distortion.
The inverter is the key equipment in a photovoltaic
system because it can control and provide several options
such as active and reactive power supply [9]. The PV
system can also contribute to improve power quality,
voltage and frequency regulation [6]. In addition, its main
role is to transform direct current (dc) energy into (ac) to
adapt the PV parameters to the grid [10].
Two types of inverters are commonly used in the PV
system, the voltage source inverter (VSI) and the current
source inverter (CSI). The first converter VSI needs dc link
capacitor to generate a constant dc voltage and requires an
ac filter inductor to generate ac voltage.
In this work, a voltage source inverter (VSI) is used
instead of the current source inverter (CSI) to provide
reactive power supply [7]. To perform the filtration function,
the PV inverter must inject the opposite current to
compensate for the non-linear current [11].This function also
requires a source to supply the voltage source inverter. Two
condensers dc are used in the proposed system [12]. The
filter control must take into account the dc voltage control.
When a photovoltaic system becomes unavailable at
night or during low illumination days, the installation
remains functional and compensates for grid harmonics [2].
This is considered as another advantage of the proposed
model. Several methods have been used to control PV
inverters [13–15]. The majority of these methods can inject
active and reactive power into the grid, with low or high
This paper presents an analysis and a simulation of a grid
connected PV system with an active power filter (APF).
The advantage of this topology is that it operates with one
voltage source inverter to control active and reactive power
and it compensates for harmonics, unlike the conventional
topologies that need two inverters for this function. The
control of the proposed system is based on the
instantaneous power theory applied to this system.
The reminder of the paper is organized as follows:
Section 2 describes the proposed model and the equipment.
Section 3 introduces the controller used in the model. The
results are presented in Section 4, while Section 5 draws
conclusions and presents some future work.
The system consists of a photovoltaic array, a capacitor,
a boost converter with a maximum power point tracker
(MPPT), an input dc capacitor, a voltage source inverter
(VSI) and an inductive filter (Fig. 1). The global system is
connected to the grid and the nonlinear load. In addition, it
uses an alternative solution with a proportional resonant
controller [8]. With an infinite gain at the resonant
frequency, the proportional resonant (PR) controller can
achieve high performance both in the elimination of steady-
state errors in the stationary frame and in the minimization
of load current distortion.
The simple model of a PV cell includes a dc power
source IL, a bypass diode, a shunt resistance Rsh and a series
resistance Rs (Fig. 2) [10]. Two parameters influence the dc
current, the ambient temperature a
T and the solar
irradiation a
G. The mathematical model of the
372 Combined operation of photovoltaic system with active power filter 2
photovoltaic cell is given by equation (1). Many PV cells
are connected in parallel or in series to produce a
photovoltaic module.
pv R
, (1)
I- PV current, 0
I- diode saturation current;
N - number of series-connected cells;
k - Boltzmann constant (1.3806503 × 10− 23 J/K);
Ta (Kelvin) - temperature of the p-n junction of the
q (1.60217646 × 10− 19 C) is the electron charge;
Rand sh
Rare the equivalent series and shunt
resistances of the module.
To achieve the desired power, several photovoltaic
modules are connected in series Nss and parallel Npp to form
a PV array (2) and (3).
cellsss VNNV .., VIPpv . . (3)
In this work, two controllers were used to manage the PV
inverter [11]. The first one was the dq current; its role is to
inject only an active and reactive power from the PV array.
The second one was a photovoltaic active power filter that
was used to compensate for harmonics and reactive power
in addition to the first controller [17]. The utility of each
controller was compared in the simulation section.
The PV inverter is a three-phase voltage source inverter
compound type: insulated gate bipolar transistor (IGBT)
semiconductor switch; it has a better efficiency and a fast
dynamic response. The voltage source inverter acts on the
IGBT switches to transit the active and reactive power [26].
In this mode, the active power filter function is integrated
with the voltage source current inverter to provide maximum
power generated by the PV system. It compensates for
harmonics and reactive power [1]. The input variables of the
controller’s active photovoltaic power filter are the active
output power of photovoltaic arrays PV
P, the dc input
voltage Vdc, the main voltages of the grid abcGrid
V, the
output current of the PV inverter abcInv
I and the load
currents abcLoad
I. The p-q theory is used to control the
active and reactive power. Figure 3 shows a simplified
diagram of the controller bloc of this system [21].
In this mode, the control strategy of this system must
have two abilities. The first is the dc voltage regulation to
balance the power between the PV units, grid and the load
[19]. The second one is the ability to produce the reference
current to generate the harmonics and reactive power
The instantaneous reactive power theory [20] was used to
generate the reference current [11]. This method is based on
voltage transformation and current variables to the αβ
coordinate based on (4):
The instantaneous active and reactive power [6] can be
calculated on α β coordinates using (5):
ivivtp . (5)
In terms of instantaneous power [18], the currents value
i and
ican be written as follows:
refInv , (6)
Fig. 1 – The proposed system model.
Fig. 2 – Equivalent circuit of a PV cell.
Fig. 3 – Control block diagram of the proposed system.
3 Hassiba Serghine et al. 373
where, p and q can be considered as the sum of dc and ac
components using (7) :
ppp ~
, (7)
p and p
~ are dc and ac components of
instantaneous active power;
q and q
~are dc and ac components of
instantaneous reactive power.
A grid reference current system must involve p
~, qand
~and supply the utility with clean energy without
harmonics and eliminate all harmonics caused by the non-
linear load. In addition, the control system must provide the
grid with the maximum active power produced by the PV
system. The last task has the role of the maximum power
point tracker (MPPT) control.
To perform both functions, the reference currents must
be calculated with the coordinates α and β. Equation (5) can
be rewritten using (8):
, (8)
where refInv
iand refInv
iare reference currents and
v are the grid voltage of the system at α β.
lossgridloadPV PPPP ref , (9)
gridloadrefInv qqq . (10)
Finally, to control the switches of the voltage source
inverter, the above equations must be transformed into the
abc system that coordinates as follows:
2. (11)
The system’s performance was tested by simulating the
dq-current and photovoltaic active power filter (PVAPF)
modes in Matlab/Simulink. The objective was to show the
benefits and advantages of the combined system. A three
phase diode bridge rectifier was implemented as a non-
linear load to generate current harmonics in the system.
Table 1 presents the system parameters used in this study.
The system operated in dq current mode during the first
period (0 to 0.1 µs) and as a photovoltaic active power filter
(PVAPF) function during the last second (0.1 µs to 0.2 µs).
The photovoltaic model used in this work is the First Solar
FS -272.
Figure 4 shows that the PV unit can produce 13 kW
during dq current function, but when the photovoltaic
power filter mode is activated, the active power decrease at
10 kW to supply the power necessary for the APF function.
Therefore, this function cannot be use during the day
because the priority is to inject the active power to ensure
the stability and balance of the grid. The APF function can
only be used according to the request of grid dispatcher or
at night to compensate for harmonics and reactive power.
On the other hand, the photovoltaic substation is still
occupied by the MPPT controller to extract the maximum
power from the PV array, thus, it is not logical to use the
active power for other tasks. In this case, the active power
must be retained to supply only the grid and the load
Table 1
System parameters
PV array
Maximum power output Pmax
Output current rating Ipv
Output voltage ratingVpv
13000 kW
35 A
368 V
Dc/ac voltage
source inverter
Output capacitor Cpv
Dc link capacitor
Dc link voltage
L filter
R filter
78.6 μF
154.69 μF
425 V
5 mH
10 Ω
R non-linear
Three-phase bridge rectifier
10 Ω
Grid Voltage rms
220 V
50 Hz
00.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2
Tim e(s )
PV Active Power
Fig. 4 – Variation of the PV output power.
00.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2
Tim e(s )
DC Voltage
Fig. 5 – Input dc voltage of PV inverter.
374 Combined operation of photovoltaic system with active power filter 4
because the price of kW and equipment are expensive.
Therefore the dispatcher’s grid promotes the renewable
energy compared to classical energy. Figure 5 shows the
variation of dc voltage.
00.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2
Tim e(s )
Grid Voltage
Fig.6. a –Grid supplied voltage waveform.
00.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2
Tim e(s )
Load Voltage
Fig. 6. b – Load voltage waveform.
00.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2
Tim e(s )
PV Voltage
Fig. 6.c – PV voltage waveform.
Fig. 7. a – Load current waveform with fast Fourier transform (FFT)
analysis tool.
Fig. 7. b – Grid current waveform with FFT analysis tool.
Fig. 7. c – PV supplied current waveform with FFT analysis tool.
Figures 6 and 7 show the load, utility, PV voltage and
current waveform. It can be observed that the PV inverter
injects the compensating current into the grid system; this
current overlaps the load current to improve the grid
In addition, Fig. 6 shows that the grid current waveforms
are in bad shape due to the nature of the load that generates
harmonics in the grid. From t = 0.1 µs, the photovoltaic
active power filter controller is activated and it begins to
5 Hassiba Serghine et al. 375
reduce the harmonics.
Figure 7 also indicates the fast Fourier transform (FFT)
analysis tool for each current. The total harmonic distortion
(THD) of the load current is 34.08 % and it is higher than
the utility. PV is equal to 26.25 % and 22.66 %,
00.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2
Tim e(s )
Ac tive power from P V S ys tem
Fig. 8. a – Active power from PV unit.
00.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2
Tim e(s )
Reactive power from P V S ys tem
Fig. 8. b – Reactive power from PV unit.
00.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2
Tim e(s )
Ac tive power from Grid Sy stem
Fig. 9. a – Active power from utility.
00.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2
Tim e(s )
P ow er(v ar)
Reactive power from G rid System
Fig. 9. b – Reactive power from utility.
00.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2
Tim e(s )
P ow er(W )
Active power from Load
Fig. 10. a – Active power from load.
00.02 0.04 0.06 0. 08 0.1 0.12 0.14 0.16 0.18 0.2
Tim e(s )
P ow er(v ar)
Reactive power from Load
Fig. 10. b – Reactive power from load.
The reactive power from the PV inverter is required to
compensate the reactive power from the grid, as shown in
Fig. 8. From 0.1 µs, the PV system provides the active and
reactive power. In this case, a part of the power is
consumed by the dc capacitor for the APF function. Figure
9 shows that the reactive power is fully compensated by the
APF controller PV.
376 Combined operation of photovoltaic system with active power filter 6
This paper presented the combination of a grid-connected
PV system connected with a parallel active filter. The
proposed system aimed to provide more options for a
photovoltaic inverter.
In recent years, the photovoltaic inverter has undergone a
major evolution and has become more attractive in the
energy system. Therefore, the combined system can provide
active and reactive power and at the same time it
compensates for harmonics and reactive power generated
by the nonlinear load.
Based on the simulations, it can be noted that the
photovoltaic active power filter (PVAPF) controller is able
to compensate for harmonics and reactive power compared
to the dq-current controller, which can only inject active
and reactive power into the grid.
The control strategy based on the instantaneous p-q
power theory was used in this system to control the voltage
source inverter. The results of the Matlab simulation
demonstrated that the proposed control is more feasible and
Consequently, other tasks for the PV inverter, such as
voltage and frequency regulation, can be introduced in
future work.
RnE : renewable energy,
THD : total harmonic distortion,
dc : direct current,
CSI : current source inverter,
VSI : voltage source inverter,
IGBT : insulated gate bipolar transistor,
PVAPF : photovoltaic active power filter,
FFT : fast Fourier transform.
The authors would like to thank Mister Nguyen Duc
Tuyen, researcher at Tokyo University of Science, Japan, for
his support in developing the Matlab simulation program.
Received on October 10, 2017
1. A. Ellis, R. Nelson, E. Von Engeln, R. Walling, J. McDowell, L. Casey,
E. Seymour, W. Peter, C. Barker, B. Kirby, Reactive Power
Interconnection Requirements for PV and Wind Plants –
Recommendations to NERC, SAND 2012–1098.
2. R. K. Varma, S. Arifur Rahman, T. Vanderheide, New Control of PV
Solar Farm as STATCOM(PV-STATCOM) for Increasing Grid
PowerTransmission Limits During Night and Day, IEEE
Transactions on Power Delivery, 30, 2, 2015.
3. J. Jiapei, C. Tiantian, L. Ling, S. Shaoze, A Control Strategy for Single-
phase Grid-Connected Inverter with Power Quality Regulatory
Function, TELEKOMNIKA Indonesian Journal of Electrical
Engineering, 12, 1, pp. 225–233, 2014.
4. A. Luo, Q. Xu, F. Ma, Y.-D. Chen, Overview of power quality analysis
and control technology for the smart grid, Journal of Modern
Power Systems and Clean Energy, 4, 1, pp 1–9, 2016.
5. S. Rajasekar, R. Gupta, Photovoltaic Array Based Multilevel Inverter
for Power Conditioning, International Conference on Power and
Energy Systems (ICPS), IEEE, 2011.
6. I.V. Nemoianu, R.M. Ciuceanu, Characterisation of non-linear three
phase unbalanced circuits powers flow supplied with symmetrical
voltages, Revue. Roumaine. Sci. Techn. – Électrotechn. et Énerg.,
60, 4, pp. 355–365, 2015.
7. T. Geury, S. Pinto, J. Gyselinck, Three-phase Power Controlled PV
Current Source Inverter with Incorporated Active Power Filtering,
Industrial Electronics Society, IECON - 39th Annual Conference
of the IEEE, 2013.
8. J. Hae-Gwang, K. Wang-Seob, L. Kyo-Beum, Second-Order
Harmonic Reduction Technique for Photovoltaic Power
Conditioning Systems Using a Proportional-Resonant Controller”,
Energies, 6, pp. 79–96, 2013.
9. M. F. Schonardie, A. Ruseler, R. F. Coelho, D. C. Martins, Three-Phase
Grid-Connected PV System With Active And Reactive Power
Control Using dq0 Transformation, IEEE/IAS International
Conference on Industry Applications - INDUSCON, 2010.
10. R. Noroozian, G. B. Gharehpetian, An investigation on combined
operation of active power filter with photovoltaic arrays, Electrical
Power and Energy Systems, 46, pp. 392–399, 2013.
11. N. Duc Tuyen, G. Fujita, PV-Active Power Filter Combination
Supplies Power to Nonlinear Load and Compensates Utility
Current, IEEE Power and Energy Technology Systems Journal, 2,
1, pp 32–42, 2015.
12. Z. Salam, T. Perng Cheng, A. Jusoh, Harmonics Mitigation Using
Active Power Filter: A Technological Review, ELEKTRIKA, 8, 2,
pp. 17–26, 2006.
13. He, J., Li, Y. W., Blaabjerg, F., Wang, X., Active harmonic filtering
using current-controlled, grid connected DG units with closed-
loop power control, IEEE Transactions on Power Electronics, 29,
2, pp. 642–653,2013.
14. S. Bouchakour, A. Tahour, H. Salah, K. Abdeladim, A. Aissaoui,
Direct power control of grid connected photovoltaic system with
linear reoriented coordinate method as maximum power point
tracker algorithm, Revue. Roumaine. Sci. Techn. – Électrotechn.
et Énerg., 59, 1, pp. 57–66, 2014.
15. K. Panagiotis, E. Lambros (Eds.), Electricity Distribution, Intelligent
Solutions for Electricity Transmission and Distribution Networks,
Springer-Verlag Berlin Heidelberg, 2016.
16. A. Yahya, H. El Fadil, J. M. Guerrero, F. Giri, H, Erguig, Three-Phase
Grid-Connected of Photovoltaic Generator Using Nonlinear
Control, Proceedings of the IEEE Conference on Control
Applications (CCA), 2014.
17. L. Naik Popavath, K. Palanisamy, A Dual Operation of PV-Statcom as
Active Power Filter and Active Power Injector in Grid Tie Wind-
PV System, International Journal of Renewable Energy rResearch,
5, 4, 2015.
18. G. Tsengenes, T. Nathenas, G. Adamidis, A three-level space vector
modulated grid connected inverter with control scheme based on
instantaneous power theory, Simulation Modelling Practice and
Theory, 25, pp. 134–147, 2012.
19. Z. Zeng, H. Yang, R. Zhao, C. Cheng, Topologies and control
strategies of multi-functional grid-connected inverters for power
quality enhancement: A comprehensive review, Renewable and
Sustainable Energy Reviews, 24, pp. 223–270, 2013.
20. A.S. Abu Hasim, Z. Ibrahim, M.H. NizamTalib, S.N. Mat Isa, J. Mat
Lazi, N. Mohd. Yakop, Photovoltaic System Connected to Three
Phase Grid Connected System Incorporating With Active Power
Filter, Australian Journal of Basic and Applied Sciences, 6, 7, pp.
345–353, 2012.
21. Y. Bouzelata, E. Kurt, R. Chenni, N. Altın, Design and simulation of a
unified power quality conditioner fed by solar energy,
International Journal of Hydrogen Energy, 40, 44, 2015.
22. A. Blorfan, P. Wira, D. Flieller, G. Sturtzer, J. Mercklé, Performance
Optimization of a Photovoltaic Generator with an Active Power
Filter Application, International Journal on Engineering
Applications, 1, 2, pp. 106–112, 2013.
23. S. Sezen, A. Aktas, M. Ucar, E. Ozdemir, A Three-Phase Three-Level
NPC Inverter Based Grid-Connected Photovoltaic System With
Active Power Filtering, 16th International Power Electronics and
Motion Control Conference and Exposition Antalya, Turkey, 21–
24 Sept 2014.
24. Z. Chelli, R. Toufouti, A. Omeiri, S. Saad, Hysteresis Control for Shunt
Active Power Filter under Unbalanced Three-Phase Load Conditions,
Journal of Electrical and Computer Engineering, Vol. 2015.
25. A. Laib, F. Krim, B. Taleb, H. Feroura, A. Kihal, Decoupled active
and reactive power control strategy of grid-connected six-level
diode-clamped inverters based on finite set model predictive
control for photovoltaic application, Revue. Roumaine. Sci.
Techn.– Électrotechn. et Énerg., 64, 1, pp. 51–56, 2019.
26. C. Buccella, C. Cecati, H. Latafat, K. Razi, A Grid-Connected PV
System with LLC Resonant Dc-dc Converter”, International
Conference on Clean Electrical Power (ICCEP), 2013.
27. E. H. Watanabe, J. L. Afonso, L. F. C. Monteiro, H. Akagi,
Instantaneous p-q Power Theory for Control of Compensators in
Micro-Grids, IEEE ISNCC - International School On Non
Sinusoidal Currents And Compensation, June 15–18, 2010,
Łagów, Poland.
... The principle of this work is based on the compensation of the fundamental reactive power and the non fundamental distortion power due to the non-linear loads connected in the local grid. Serghine et al. [3] describe a combination of a grid-connected PV system with a parallel active filter. In this work, the authors propose a classical control strategy based on the instantaneous p-q theory used to control the voltage source inverter. ...
Full-text available
In order to better adapt to the variation in solar irradiation and to improve the efficiency of the photovoltaic generator, i.e. to maximize the power delivered to the grid. Several criteria’s for optimizing the efficiency of the photovoltaic system have been applied. Among them, the algorithms for tracking the optimal operating point of the photovoltaic panels that called Maximum Power Point Tracking (MPPT). In this article, a PV generator (GPV) has been connected to the power grid, as a result, direct consequence is in the deterioration of the voltage wave and thus the quality level of the energy supplied to the consumers. To overcome these problems of harmonic pollution, active power filtering is proposed as an efficient solution to improve grid power quality. This paper therefore proposes to examine the characteristics of an association between a photovoltaic generator (PVG) that aims at injecting active power into the electrical grid and a parallel active filter that has the task of eliminating disturbances present in this grid. The theory of the two-phase method with Adaline harmonic extraction is applied for the extraction of the reference currents according to the DQ reference frame. Finite set mode predictive current control (FS-MPCC) applied on PAF has been proposed in order to compensate undesirable harmonic, and reactive power resulting from a non-linear load. A Global Maximum Power Point Tracking (GMPPT) algorithm based Adaline method has been suggested for extracting power from PVG. A simulation under Matlab/Simulink of the global system proves the robust performance capability of the suggested Adaline Neuro-Predictive (ANP) control to simultaneously provide harmonic current compensation, power factor correction and solar power energy injection into the grid.
... The majority of papers on power quality of renewable energy sources concern photovoltaic systems. These articles are mainly devoted to solutions that integrate PV systems with devices which enable reactive power compensation and higher harmonic filtering [14][15][16][17][18][19] as well as some specific solutions dedicated for inverters used in PV systems [20,21]. ...
Full-text available
Network working conditions are influenced noticeably by the connection of renewable energy sources to distribution networks. This becomes more and more important due to the increase in renewable energy source penetration over the last few years. This in turn can lead to a mass effect. As a result, the classical open network model with simple unidirectional direction of energy flow has been replaced with an active model that includes many local energy sources. This paper deals with the analysis of long- and short-term changes in power and energy generated by three types of renewable energy sources with similar rated power and which operate in the same region (i.e., located no more than tens of kilometers away). The obtained results can be a starting point for a broader evaluation of the influence of renewable energy sources on power quality in power systems, which can be both positive (supply reliability) and negative (voltage fluctuations and higher harmonics in current and voltage waveforms). It is important not only to correctly place but also to assure the diversity of such sources as it has been confirmed by the source variability coefficient. The long-term analysis allows us also to estimate the annual repeatability of energy production and, furthermore, the profitability of investment in renewable sources in a given region.
Full-text available
Key words: Solar energy, Six-level neutral point clamping (NPC) inverter, Decoupled active and reactive power control, Finite set model predictive control. In this paper, a decoupled active and reactive power control strategy based on finite set model predictive control is proposed to control grid connected six-level NPC inverters for photovoltaic application. The purposes of this strategy are: injection control of the active power produced by photovoltaic system as well as the reactive power requested by the grid operator, also the assurance of high grid current quality and dc link capacitors voltages balance. Using the discrete time model of six level NPC inverter tied to the network, the proposed strategy is based on prediction of the future behavior of active and reactive grid power values and dc link capacitor voltages for 216 possible switching states and compare them with using a cost function for obtaining the optimal vector and applying it during the next sampling time. The global system is simulated using Matlab/Simulink and Simpower system packages. The performance of the proposed strategy is evaluated under the step change in the solar irradiation and the reactive power reference. The obtained results proves that the proposed strategy provide high performance control.
Full-text available
With the wide application of non-linear loads and the large-scale access of distributed energy generations based on power electronics equipments, power quality problems in the distribution network are increasingly serious with new characteristics. Further in-depth research is of great significance in theory and practice. This paper provides an overview of power quality analysis, compensators, and control technologies under the new situation of smart grid. It focuses on the topologies and control methods for power quality conditioners, especially new characteristics of power quality and applicable control technologies in microgrids and distributed power plants. Finally, trends and prospects of power quality control technology are introduced, which is important to achieve security and efficient operation of the smart grid.
Full-text available
The present study continues the research presented in a previous article by the same authors focussed on the power theory of Professor Andrei Tugulea, dedicated to non-linear three-phase unbalanced circuits. The defmed symmetry, non-symmetry and residual (distorting) active and reactive powers flow and conservation are further investigated in three-phase circuits with neutral. Correspondingly, the original theory introduced the symmetry power factor (SPF), the non-symmetry power factor (NPF) and the distorting power factor (DPF) as suitable quantities for characterizing such three-phase circuits (with or without neutral). The paper proves the validity of the theory extended to three-phase, circuits. with zero impedance neutral on test-circuits simulated in PSpice software. The resulting data are used in a dedicated software usable in on-line or off-line calculations, as well as on power grid automated management.
Conference Paper
Full-text available
This paper presents a three-phase three-level neutral point clamped (NPC) inverter based single-stage grid-connected photovoltaic (PV) system with shunt active power filter (APF) functionality. The proposed system can perform both the maximum real power injection with the perturb and observe (P&O) maximum power point tracking (MPPT) algorithm from the PV panels into the grid and active power filtering to compensate the load current harmonics. Thus, the PV system operates more efficiently compared to the conventional PV systems and can be useful for power system applications. Control of the proposed system is based on synchronous reference frame control algorithm and hysteresis band current control technique. The effectiveness of the proposed system is demonstrated with Matlab/Simulink simulations and validated through dSPACE DS1103 real-time control platform based laboratory experimental results.
Full-text available
Maximum Power Point Tracking (MPPT) for photovoltaic (PV) systems maximizes the power that can be transferred from the PV system to an electrical system here we use the active power filter. To maximize the PV panel output power, perturb and observe (P&O) maximum power point tracking (MPPT) has been implemented into the PV system. Through a boost DC-DC converter, for rapidly changing solar irradiance the (P&O) method is unable to carry out the maximums power point values. This paper presents an intelligent method for the purpose of MPPT, based on fuzzy logic controller (FLC), and applied to a converter circuit. The fuzziness determines the size of the perturbed voltage when there is a rapid changing in solar irradiation. A control scheme is presented which allows better control of the converter current reference using voltage and current from the PV system as inputs to the MPPT perturb and observes method. The performance of the proposed FLC is tested by simulation and the results show that the FLC is faster in finding the maximum power point than the conventional perturbation and observation method. In order to avoid the problems and difficulties of regulation and variation of the DC bus due to losses in the active power filter (transistors and the output filter), a constant voltage on the DC side of the inverter was proposed, it is a photovoltaic generator which is used to ensure constant amount of power force required to maintain the DC voltage side around its reference value.
Full-text available
Grid-connected inverters are key components of distributed generation systems (DGSs) and micro-grids (MGs), because they are effective interfaces for renewable and sustainable distributed energy resources (DERs). Recently, multi-functional grid-connected inverters (MFGCIs) have attracted more and more attention for their benefits on auxiliary services on power quality enhancement in DGSs and MGs. These kinds of converters can not only achieve the power generation of DERs, but also can perform as power quality conditioners at their grid-connected points. It should be noted that these functionalities are optimally organized in the same device, which can significantly enhance the cost-effective feature of the grid-connected inverter, as well as can decrease the investment and bulk compared with multiple devices with independent functionalities. MFGCIs are especially suitable for DGSs and MGs application due to their good performances and benefits. Topologies and control strategies of MFGCIs are comprehensively reviewed in this paper. Additionally, detailed explanation, comparison, and discussion on MFGCls are achieved. Furthermore, some future research fields on MFGCls are well summarized.
Full-text available
Presently, quality problems in grid-integrated applications take great interest because of the growing applications in power electronics. The elimination of the harmonics in the grid and the usage of clean energy resources in the power electronics applications become popular world widely. In the present paper, a unified power quality conditioner fed by solar energy which can also export active power to the grid is proposed. The conditioner uses a photovoltaic (PV) system and its topology is made up of a hybrid active power filter combination. This combination bases on a parallel active power filter, which shares a common DC voltage assured by the photovoltaic system with a serial active power filter. According to the analyzes, the proposed unified power quality conditioner eliminates both the supply current distortion caused by a non-linear load and the load voltage distortion introduced after adding fifth and seventh harmonics to the AC main voltage. In addition, the proposed unified power quality conditioner exports the photovoltaic power to the grid using a boost converter, perturbed and observed maximum power point tracking algorithm, compensates the reactive power and filters the current and voltage harmonics confirmed by the total harmonic distortion values, such as 4.76% and 3.86%, respectively. The design and the analyses have been performed with MATLAB/Simulink software. The simulation system determines the performances of such system and offers future perspectives on unified power quality conditioners.
Full-text available
This paper proposes a second-order harmonic reduction technique using a proportional-resonant (PR) controller for a photovoltaic (PV) power conditioning system (PCS). In a grid-connected single-phase system, inverters create a second-order harmonic at twice the fundamental frequency. A ripple component unsettles the operating points of the PV array and deteriorates the operation of the maximum power point tracking (MPPT) technique. The second-order harmonic component in PV PCS is analyzed using an equivalent circuit of the DC/DC converter and the DC/AC inverter. A new feed-forward compensation technique using a PR controller for ripple reduction is proposed. The proposed algorithm is advantageous in that additional devices are not required and complex calculations are unnecessary. Therefore, this method is cost-effective and simple to implement. The proposed feed-forward compensation technique is verified by simulation and experimental results.
This paper presents a novel concept of utilizing a photovoltaic (PV) solar farm inverter as STATCOM, called PV-STATCOM, for improving stable power transfer limits of the interconnected transmission system. The entire inverter rating of the PV solar farm, which remains dormant during nighttime, is utilized with voltage and damping controls to enhance stable power transmission limits. During daytime, the inverter capacity left after real power production is used to accomplish the aforementioned objective. Transient stability studies are conducted on a realistic single machine infinite bus power system having a midpoint located PV-STATCOM using EMTDC/PSCAD simulation software. The PV-STATCOM improves the stable transmission limits substantially in the night and in the day even while generating large amounts of real power. Power transfer increases are also demonstrated in the same power system for: 1) two solar farms operating as PV-STATCOMs and 2) a solar farm as PV-STATCOM and an inverter-based wind farm with similar STATCOM controls. This novel utilization of a PV solar farm asset can thus improve power transmission limits which would have otherwise required expensive additional equipment, such as series/shunt capacitors or separate flexible ac transmission system controllers.
This paper presents the concept of utilization of PV-solar farm as static synchronous compensator (PV-Statcom) to mitigate power quality issues like poor power factor, voltage variations and current harmonics in power systems. The proposed system includes non linear load, wind generator and solar PV- Statcom. The solar PV - Statcom compensating harmonics produced by local load, supplies reactive power required by the wind genrator in addition to active power injection is demonstrated in this reseach work. The PV-Statcom control pattern for enhancing quality of power is simulated in MATLAB/Simulink in simpower system block set.