Research On The Control Strategy Of Active Power Filter Based On Four-Leg Voltage-Source Inverters

Harmonic pollution in the power system exerts an adverse influence on the quality of electrical energy, such as reduces the supply efficiency of electricity equipment, endangers the safety of the public power grid. Active Power Filter (APF)is considered as one of the best solutions to resolve this issue. APF picks three-phase current into harmonic detection unit to separate the fundamental current component and harmonic component, puts the harmonic current into PWM command unit which can send PWM signals to drive four-leg converter to produce compensating current which could offset the distortion.The compensate current control strategy of APF based on four-leg voltage-source inverters which used in three-phase four-wire power system is studied in this paper. The traditional control method such as Three-dimension space vector modulation and hysteresis current control are introduced firstly, there advantage and deficiency are analysed also. An improved hybrid current control based on space vector is proposed, which combines the merits of the traditional control with the decoupled control theory. MATLAB/Simulink simulation results show that this method has the problem of inexhaustive decoupling. The farther improved method of three-dimension vector current tracking control is the effectual way to solve the problem above and has a well compensation.All of the analysis and conclusion of the control method are evaluated by the simulation results using MATLAB/Simulink program. The simulation results show that the farther improved three-dimension vector current tracking control method proposed in this paper is valid and feasible. The results of this paper are helpful to the optimal design of the experimental equipment.