2904 IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, VOL. 56, NO. 8, AUGUST 2009 A New Control Technique for Three-Phase Shunt Hybrid Power Filter Salem Rahmani, Abdelhamid Hamadi, Student Member, IEEE, Nassar Mendalek, Member, IEEE, and Kamal Al-Haddad, Fellow, IEEE Abstract—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 sys- tem is first elaborated in the stationary “abc” reference frame and then transformed into the synchronous orthogonal “dq” reference frame. The “dq” 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 uti- lized 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. Index Terms—Harmonic compensation, hybrid power filter, modeling, nonlinear control. I. I NTRODUCTION S EVERAL pieces of electrical equipment in industries are nowadays using processed power to reduce power con- sumption, mechanical maintenance, down time, and cost of production. The processed power is generally achieved through the use of power converters to control the speed of motors in modern adjustable speed drives (ASDs). These power convert- ers draw nonsinusoidal currents contributing to the degradation of power quality at ac mains. The power converters consist generally of rectifiers at front end which, due to their nonlinear nature, inject harmonic currents into the utility. The propagation of these harmonics causes many problems to the power net- work, such as transformer overheating, harmonic resonance in the utility, increased losses, malfunction of protection devices, Manuscript received July, 27, 2007; revised August 20, 2008. First published January 9, 2009; current version published July 24, 2009. This work was supported by the Canada Research Chair in Energy Conversion and Power Electronics. S. Rahmani, A. Hamadi, and K. Al-Haddad are with École de Technologie Supérieure, University of Québec, Montreal, QC H3C 1K3, Canada. N. Mendalek is with the Department of Electrical, Computer and Communi- cation Engineering, Notre Dame University, Louaize, Lebanon. Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/TIE.2008.2010829 and interference to communication network and electronic systems. Several techniques of compensation are proposed to improve the power quality and to reduce the dimensions of the active filters [1]. Traditionally, passive LC filters have been used to eliminate harmonic currents and to improve the power factor of ac mains. However, these passive filters have many drawbacks such as tuning problems and series and parallel resonances [2] [3]. To avoid the resonance between an existing passive filter and the supply impedance, typical shunt or series active filter topologies have been proposed in the literature [4]–[9]. However, these topologies suffer from high kilovolt–ampere rating of the ac- tive filter. The boost converter forming the shunt active filter requires high dc-link voltage in order to effectively compensate higher order harmonics. On the other hand, a series active filter needs a transformer that is capable to withstand full load current in order to compensate for voltage distortion [10]. Hybrid filters effectively mitigate the problems of a passive and an active filter and provide cost-effective harmonic compensation, particularly for high-power nonlinear loads [3]. A parallel hybrid power filter system consists of a small-rating active filter in series with a tuned passive filter. The active filter is controlled to act as a harmonic compensator for the load by confining all the harmonic currents into the passive filter. This eliminates the possibility of series and parallel resonances. A number of control concepts and strategies of active power filters have been reported in the literature [11]–[19]. The most popular are the time domain methods such as the notch filter, the instantaneous reactive power theory, and the synchronous reference frame theory. The main advantage of these time domain control methods compared to the frequency domain methods based on the fast Fourier transform is the fast response, whereas the frequency domain methods provide an individual selective harmonic detection which is not the case in time domain methods. In [20], a nonlinear control technique is proposed to enhance the dynamic performance of a shunt active power filter which is modeled in the synchronous orthogonal “dq” frame. The exact feedback linearization theory is applied in the design of the controller. This control strategy allows the decoupling of the currents and enhances their tracking behavior and improves the dc-voltage regulation. In [21], the authors reported an adaptive nonlinear control law applied to a three-phase three- level neutral-point-clamped boost rectifier operating under se- vere conditions. The control technique consists in applying an adaptive nonlinear control to the exact nonlinear model of the rectifier obtained in the (d, q, 0) reference frame. In [22], linear 0278-0046/$26.00 © 2009 IEEE