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Performance of single-phase converter connected to utility grid highly depends on accurate and fast detection of the grid voltage parameters, and to deal with these constraints even under quality drifts of grid voltage, various synchronization methods have been put forward. The most popular single-phase synchronization structures are those using the quadrature signal generator with phase-locked loops (QSG-PLLs). Among various QSG-PLLs, the PLL based on the third-order sinusoidal integrator (TOSSI-PLL) presents an effective synchronization scheme when the voltage is affected by frequency variation, sag, swell and high-frequency harmonics, but its efficiency decreases when low frequency harmonics have a high rate. This paper proposes an enhanced third-order sinusoidal integrator PLL (ETOSSI-PLL) for single-phase systems to upgrade the accuracy of the PLL. Simulation results of ETOSSI-PLL and TOSSI-PLL under grid voltage abnormalities are compared to show improved performance.

This paper has presented improved control structure based direct power control (DPC) applied for shunt active power filtering. Basically, DPC control strategy employs instantaneous active and reactive power terms as controlled variables. This work introduces an integration concept of predictive control algorithm for shunt active power filter system application. Process of this latter adopts discrete model of PWM converter in the aim to predict future behaviour of the system. Switching vector selection principles for predictive control is very different compared to conventional method. For conventional DPC the selection is performed via heuristic switching table while predictive DPC algorithm takes on an optimized way based on cost function minimization depending to power errors, this latter evaluate the effects of each active voltage vector and the one reducing the cost function is chosen to be applied in the next sampling period. The application of optimal switching state leads to regulate the input active and reactive power which resulted in the cancellation of harmonic power component contained in the network. Simulation results are presented to verify the validity and effectiveness of the proposed predictive DPC in terms of dynamic and steady state performance for shunt active power filtering application.

To minimize the total harmonic distortion (THD) and improve the power factor (PF), this paper presents a comparative study between two techniques of shunt power active filter (SPAF) by a selective action of harmonics. These two techniques are based on the SAPF of certain low frequency harmonics (5th and 7th) whose identification of the harmonics of references of the first is made by the axis synchronous d-q of the Park, and the second is done by the approach of self-tuning filter (STF) Thereafter, The active simultaneously filtering of the 5th and 7th harmonics of the current of load catches. The shapes of the signals and the THD values resulting from the results of digital simulations (Matlab-Simulink) elaborate the effectiveness and the best technique of this type of filtering.

PurposeThe paper aims to explain the investigation of the space vector modulation (SVPWM), in shunt active powers filters (APFs) field, for controlling the generated current.Design/methodology/approachWith the inclusion of the SVPWM control technique, the proposed topology of the two‐level shunt active power filter (APF), based on IGBTs, besides its efficiency in harmonics cancellation and power factor correction, contributes in switching power losses reduction.FindingsThe paper provides an extended theoretical study and a detailed explanation of the application of the SVPWM on shunt APFs, and demonstrates how power losses can be reduced by limiting the switching process to the two thirds of the pulse duty cycle.Research limitations/implicationsSimulation and experimental validations will still be requested as to the accuracy of the model and the applicability to the polluted electrical power systems plants.Practical implicationsThe paper formulates an easy mathematical method to investigate the SVPWM algorithm with clarification of its various steps. It offers a benefit to people engaged in theoretical and practical research in APFs, inverters, and PWM modulation strategies.Originality/valueSince, there are few studies which clarify the application of the SVPWM on APFs, the paper may help to understand the mathematical implementation of this control strategy both for controlling the APF current and for gating signals generation.

Harmonics contamination is a serious and a harmful problem in electric power systems. Active power filtering constitutes one of the most effective proposed solutions. A shunt active power filter that achieves low current total harmonic distortion THD, reactive power compensation, and power factor correction is presented. The topology is based on IGBT's voltage inverter, intended to damp harmonics produced by a diode rectifier. The main paper's contribution is the use of the notch filter method, consisting solely of two serial band-pass filters, for reference currents calculation, and the application of fuzzy logic for better active filter current control accuracy. The gating signals were generated through the carrier-based PWM strategy. Simulation works of the studied model, using SIMULINK under MATLAB software, revealed satisfying results in transient and steady states. Keywords: Harmonics, Shunt active power filter, Band-pass filters, Fuzzy logic, PWM strategy

The aim of this paper is to compare two different control structures. The Simple Direct Power Control (DPC) and the Direct Power Control with Space Vector Modulation (DPC- SVM) for two level converter applications. The first strategy (DPC) has been developed to control the instantaneous active and reactive power directly by selecting the optimum switching state of the converter. Applied to the Pulse Width Modulation (PWM) converter its main feature is to improve the total power factor and efficiency, even harmonics components existence. In the second structure, the active and reactive powers are used as (PWM) control vari- ables instead of the three-phase line currents usually used in other techniques. It is shown that DPC-SVM exhibits several properties; good dynamic response, constant switching fre- quency, and in particular it provides a sinusoidal line currents. Simulation and experimental results has shown that both control structures achieve good performances. DOI: http://dx.doi.org/10.11591/ijece.v4i3.6074

This paper deals with a wind energy conversion system (WECS), based on a doubly fed induction generator (DFIG) and an electromechanical active power filter (APF). The objective is to respond simultaneously to electric energy requirement and power quality concerns. The proposed WECS is able not only to track the maximum power point of the wind energy but also to dampen harmonic currents from the grid line. To achieve these purposes, back-to-back pulse width modulation (PWM) voltage source converters (VSCs) are employed to excite the DFIG rotor. To control the power converters, two regulation loops, following the field oriented control (FOC) method, have been conceived. The first loop, dedicated to the rotor converter, enables a decoupled control of active and reactive powers flows. As well, it permits the cancellation of the most noteworthy harmonics from the utility current. The second loop, devoted to the front-end converter (FEC), makes it possible to regulate the DC-bus voltage shared between the two converters. Furthermore, the paper provides a study of the DFIG sub and super-synchronous operating modes which can be reached by acting on the wind speed. To demonstrate the performance of aforementioned WECS, a Matlab/Simulink model was established and simulated. Results seem to be very promising.

A straightforward approach to suppress three-phase supply current and load voltage distortions is presented. This latter uses the unified power quality conditioner (UPQC) topology made up of a hybrid active power filter (APF) combination based on a series APF, sharing a common DC voltage with a parallel APF, and passive filters. Supply current distortion is introduced by connecting a non-linear load, while load voltage distortion occurs after adding 5th and 7th harmonics to the AC main voltage. The series APF controller forces load voltage to be sinusoidal, whereas parallel APF and passive filters counter harmonic contents from supply current. A model established under Matlab-Simulink software shows the performance of such approach.

Generally, low harmonic frequencies such as the harmonic of the order 5 and 7 have a great influence to deteriorate the network current and interim the grid power factor. The objective is to cancel out the selected harmonic order from the network current. The shapes of waves and the values of the THD of the network current before and after applying the proposed technique are introduced. The system is simulated and investigated using MATLAB/Simulink. The results prove the effectiveness of the design and control strategy (α–β). This paper deals with design, analysis and simulation of a three phase three wire shunt selective active power filter. It compensates the harmonic currents selectively under balanced power network. In order to improve, the power factor of the supply network, an advanced control approach based on a multivariable filter is adopted. The novelty of the proposed control approach developed in this paper is to use a multi–variable filter (MVF), which can extract the harmonics content of load current reference, according to the axis of Concordia.

This paper deals with a wind energy conversion system (WECS), based on a doubly fed induction generator (DFIG) and an electromechanical active power filter (APF). The objective is to respond simultaneously to electric energy requirement and power quality concerns. The proposed WECS is able not only to track the maximum power point of the wind energy but also to dampen harmonic currents from the grid line. To achieve these purposes, back-to-back pulse width modulation (PWM) voltage source converters (VSCs) are employed to excite the DFIG rotor. To control the power converters, two regulation loops, following the field oriented control (FOC) method, have been conceived. The first loop, dedicated to the rotor converter, enables a decoupled control of active and reactive powers flows. As well, it permits the cancellation of the most noteworthy harmonics from the utility current. The second loop, devoted to the front-end converter (FEC), makes it possible to regulate the DC-bus voltage shared between the two c...