Abdelhamid Hamadi

A Lyapunov-Function-Based Control for a Three-Phase Shunt Hybrid Active Filter

In this paper, an energy-based Lyapunov function control technique is developed for a three-phase shunt hybrid active filter (SH-AF) to compensate harmonics generated by nonlinear loads and is applied for balanced operation. The method provides compensation for harmonic load current components. The strategy determines the control law that makes the derivative of the Lyapunov function always negative for all values of the states. The dc bus voltage of the SH-AF is maintained to 50 V, which is significantly lower than that of the conventional hybrid active filter. The rating of the active filter in the SH-AF system is much smaller than the one used in the conventional shunt active power filter because the passive filter takes care of the major burden of compensation. The SH-AF performances, during both nominal and severe operating conditions, are then evaluated using a dSPACE DS1104 controller board, supported by a Matlab/Simulink Real-Time Workshop environment. A significantly high correlation between the experimental results and the theoretical model, implemented with Simulink/Matlab, is obtained.

A New Control Technique for Three-Phase Shunt Hybrid Power Filter

This paper presents a nonlinear control technique for a three-phase shunt hybrid power filter (SHPF) to enhance its dynamic response when it is used to compensate for harmonic currents and reactive power. The dynamic model of the SHPF system is first elaborated in the stationary ldquoabcrdquo reference frame and then transformed into the synchronous orthogonal ldquodqrdquo reference frame. The ldquodqrdquo frame model is divided into two separate loops, namely, the two current dynamic inner loops and the dc-voltage dynamic outer loop. Proportional-integral (PI) controllers are utilized to control the SHPF input currents and dc-bus voltage. The currents track closely their references so that the SHPF behaves as a quasi-ideal current source connected in parallel with the load. It provides the reactive power and harmonic currents required by the nonlinear load, thereby achieving sinusoidal supply currents in phase with supply voltages under dynamic and steady-state conditions. The SHPF consists of a small-rating voltage-source inverter (VSI) in series with a fifth-harmonic tuned LC passive filter. The rating of the VSI in the SHPF system is much smaller than that in the conventional shunt active power filter because the passive filter takes care of the major burden of compensation. The effectiveness of the control technique is demonstrated through simulation and experimentation under steady-state and dynamic operating conditions.

A Combination of Shunt Hybrid Power Filter and Thyristor-Controlled Reactor for Power Quality

This paper proposes a combined system of a thyristor-controlled reactor (TCR) and a shunt hybrid power filter (SHPF) for harmonic and reactive power compensation. The SHPF is the combination of a small-rating active power filter (APF) and a fifth-harmonic-tuned LC passive filter. The tuned passive filter and the TCR form a shunt passive filter (SPF) to compensate reactive power. The small-rating APF is used to improve the filtering characteristics of SPF and to suppress the possibility of resonance between the SPF and line inductances. A proportional-integral controller was used, and a triggering alpha was extracted using a lookup table to control the TCR. A nonlinear control of APF was developed for current tracking and voltage regulation. The latter is based on a decoupled control strategy, which considers that the controlled system may be divided into an inner fast loop and an outer slow one. Thus, an exact linearization control was applied to the inner loop, and a nonlinear feedback control law was used for the outer voltage loop. Integral compensators were added in both current and voltage loops in order to eliminate the steady-state errors due to system parameter uncertainty. The simulation and experimental results are found to be quite satisfactory to mitigate harmonic distortions and reactive power compensation.

A Hybrid Passive Filter Configuration for VAR Control and Harmonic Compensation

This paper proposes a novel topology for a three-phase hybrid passive filter (HPF) to compensate for reactive power and harmonics. The HPF consists of a series passive filter and a thyristor-controlled-reactor-based variable-impedance shunt passive filter (SPF). A mutual-inductance design concept is used to reduce the series passive filter inductance rating. The special features of the proposed HPF system are as follows: 1) insensitivity to source-impedance variations; 2) no series or parallel resonance problems; 3) fast dynamic response; and 4) significant size reduction in an SPF capacitor. The performance of the proposed HPF system is validated by simulation, as well as by experimentation, under different load conditions. Experimental and simulation results show that the proposed system can effectively compensate all voltage and current harmonics and reactive power for large nonlinear loads.

Comparison of fuzzy logic and proportional integral controller of voltage source active filter compensating current harmonics and power factor

This paper presents and compares the performance of two control techniques namely fuzzy logic FL and proportional integral PI applied to a voltage source inverter operating as an active power filter. The controllers permit to compensate harmonics and reactive power generated by the non-linear load simultaneously. This work is performed in order to make an accurate comparison of fuzzy logic controller and classical control technique such as PI controller. The fuzzy logic controller implemented uses Sugeno method, and is optimized by using adaptive neuro fuzzy inference system ANFIS. Steady state and transient performance are compared for different methods. The obtained results show the fuzzy logic controller is performing much better than the PI controller over a wide operating range.

Original article: A DSP-based implementation of an instantaneous current control for a three-phase shunt hybrid power filter

This paper presents the design and implementation of an instantaneous current control technique for a three-phase shunt hybrid power filter (SHPF) to compensate harmonics generated by non-linear loads. The control of the SHPF is based on synchronous reference frame (SFR) method. The SHPF consists of a small-rated voltage source inverter (VSI) in series with an LC passive filter. The proposed control algorithm of the SHPF requires less number of current sensors compared to the instantaneous reactive power theory based current control algorithm, which resulting in an overall cost reduction. Proportional-Integral (PI) controller is used to control the SHPF dc-bus voltage. The inner loops ensure the shaping of the ac currents, through the control of dq current components. The outer loop regulates the dc-bus voltage to its set reference and provides the current reference to the inner current loops. The SHPF can maintain the low level of dc-bus voltage at a stable value below 50V, which is one of its advantages in comparison to the conventional hybrid power filter. The systems performance, during both nominal and severe operating conditions, are then evaluated in real-time using the dSPACE DS1104 controller board, supported by a Matlab/Simulink Real-Time Workshop environment.

Digital Control of a Shunt Hybrid Power Filter Adopting a Nonlinear Control Approach

This paper proposes a nonlinear derivative-less control approach for controlling a three-phase shunt hybrid power filter (SHPF). The dynamic model of the SHPF system is first elaborated in the stationary frame and then transformed into a “dq” reference frame. The control system is divided into two separate loops, namely the two current dynamics inner loop and the dc voltage dynamic outer loop. The exact feedback linearization technique is used to decouple the inner loop variables. Proportional-integral controllers are utilized to control the SHPF input currents and dc-bus voltage. The proposed nonlinear control is first simulated and then validated on a 2.5-kVA laboratory prototype supported by the DS 1104 digital real-time controller board of dSPACE. Satisfactory results, such as low-ac-current total harmonic distortion, fast step response, and high robustness under load variation, are obtained. Significantly high correlation between the experimental results and the theoretical model, implemented with SIMULINK/Matlab, is obtained.

Experimental Investigation on a Hybrid Series Active Power Compensator to Improve Power Quality of Typical Households

In this paper, a transformerless hybrid series active filter using a sliding-mode control algorithm and a notch harmonic detection technique are implemented on a single-phase distribution feeder. This method provides compensation for source current harmonics coming from a voltage fed type of nonlinear load (VSC) and reactive power regulation of a residential consumer. The realized active power filter enhances the power quality while cleaning the point of common coupling (PCC) from possible voltage distortions, sags, and swells initiated through the grid. Furthermore, to overcome drawbacks of real-time control delay, a computational delay compensation method, which accurately generates reference voltages, is proposed. Based on an improved compensation strategy, while the grid current remains clean even with a small compensation gain, voltage disturbances initiated by the power system are obstructed by the compensator, and the PCC became free of voltage harmonics and protected from sag and swell. Simulation and experimental results carried on a 1.6-kVA prototype are presented and discussed.

Modeling, control and simulation of DFIG for maximum power point tracking

This paper deals with the modeling, analysis, control and simulation of a doubly-fed induction generator (DFIG) driven by a wind turbine. This grid connected wind energy conversion system (WECS) is composed of DFIG and two back-to-back PWM voltage-source converters in the rotor circuit. A mathematical model of the machine, derived in an appropriate dq reference frame is established. The grid voltage oriented vector control is used for the grid side converter (GSC) in order to maintain a constant DC bus voltage and to compensate for reactive power at the power network. The stator voltage orientated vector control is adopted in the rotor side converter (RSC) control strategy, providing efficient handling of active and reactive power at the stator, as well as a maximum power point tracking (MPPT) method for the DFIG-based wind turbine. The proposed system is simulated for different operating conditions to illustrate the reliability of the control technique. Corresponding system simulation results under nonlinear load variations and wind speed transients are presented to demonstrate the significance of MPPT in WECS, and the effectiveness of adopted control technique.

Power Quality Enhancement of Smart Households Using a Multilevel-THSeAF With a PR Controller

In this paper a multilevel transformerless hybrid series active filter is proposed to enhance the power quality of a single-phase residential household. The proposed topology reflects new trends of consumers toward electronic polluting loads and integration of renewable sources which in fact may lead to the scope of a reliable and sustainable supply. This paper contributes to improvement of power quality for a modern single-phase system and emphasis integration of a compensator with energy storage capacity to ensure a sustainable supply. A proportional resonant (P+R) regulator is implemented in the controller to prevent current harmonic distortions of various non-linear loads to flow into the utility. The main significant features of the proposed topology include the great capability to correct the power factor as well as cleaning the grid simultaneously, while protecting consumers from voltage disturbances, sags, and swells during a grid perturbation. It investigates aspects of harmonic compensation and assesses the influence of the controllers choice and time delay during a real-time implementation. Combinations of analysis and experimental results performed on a laboratory setup are presented for validation.