Studies On Control Strategy To Improve The Performance Of High Volume Shunt Active Power Filter

Along with the need of high efficiency of power supply, the power electronics equipments are used more and more widely, and the grid is contaminated more and more badly. The harmonics can make other equipments malfunction, and even endanger the grid. Active power filter (APF) gains comprehensively research because of its ability to compensate the harmonics changing in both frequency and magnitude.This thesis does some analysis, design and simulation to improve the efficiency and to get good transient-static performance of high volume active filter based on a "380V, 260kVA active power filter" supported by a company. This thesis firstly presents main circuit of active filter connected to the grid through an LCL filter, and further points out the advantages of this circuit to attenuate switching ripple used in low switching frequency and high volume situation. State feedback is select to choke the resonance of LCL filter by comparing with the PI control.Supposing the grid as disturbance, mathematic models of LCL filter in abc three-phase stator coordinate is established, then this thesis makes pole assignment by selected the expectation pole. For remove the influence of the grid input on APF tracking the reference, introduces feed forward of grid voltage, and gives the concretely formula of the feed forward. The estimator is designed later by bringing the gird input model into the estimator to eliminate. Because of the fluctuation of inductance L2 considering the on site installation of APF, the flexibility of controller have been studied. Repetitive controller also is designed out of state feedback control loop to improve static performance of APF.Finally, a system model of APF to compensate 1MW three phase rectifier load is established. The simulation results confirm the correction of design and research work.