Three-phase Shunt Active Filter Harmonic Detection And Compensation Control Simulation Study

With the rapid development of power electronics technology, more and more nonlinear loads and a variety of converter devices have been widely used in power systems, the increasingly severe harmonic pollution has a serious influence on the power quality. As the most effective power electronic devices of harmonic suppression, compared with the traditional passive filter, active power filter (APF) has an excellent compensation effect and dynamic tracking compensation, which has been rapidly developing.Based on the latest references and technology of APF at home and abroad, the paper explains working principles and topology structures of APF. The APF compensation performance depends on harmonic current detection method and current track-control methods.Based on the description of the detecting method widely used and the characteristics of three-phase three-line shunt APF, this paper chooses the ip-iq detecting method based on the instantaneous reactive power theory and the adaptive closed-loop detecting method based on the adaptive interference cancellation principle.Currently, the triangular wave comparison control and the tracking control of hysteresis are the main methods of current tracking control. Given the shortcomings of the two methods, this paper proposes a novel control method:The Variable Structure Control of APF system based on inverse system.Considering the APF system is a multiple-input multiple-output and coupled nonlinear system, the original system model of APF is linearized and decoupled to be a pseudo-linear system by inverse-system method.Then it adopts Variable Structure Control (VSC)theory, and designs the variable structure control laws of this pseudo-linear system.Under the conditions of power asymmetry, the supply voltage waveform distortion and load sudden change, the ip-iq and VCS system of APF and the self-adapting and VCS system of APF are established with Matlab/simulink and simulinked in eight operating modes. The simulation shows that the compensation current of the self-adapting and VCS system follows the harmonics reference signal fast and precisely, the DC voltage also reaches the fixed value quickly, and the performances of APF to compensate harmonics is excellent. So the control method of APF system presented in this paper is proved feasible and effective.