Research Of Distortion Current Detection Method And Compensation Current Control Method

As an ideal device to eliminate harmonic and improve power factor, active power filter can dynamically compensate the harmonic, reactive power, negative and zero sequence current in the nonlinear load. It makes up for the drawbacks of the passive power filter. Therefore, people pay more attention to it.There are two key problems in the active power filter, one is the real-time and accurate detection for the distortion current in the nonlinear load, the other is the accurate control for the compensation current which was detected.After comparing the commonly used distortion current detection methods at present, a distortion current detection method which is based on adaptive linear element is studied in this paper. It is algorithm-simpled, real-time and adaptive and can be extended to three-phase circuit. The M files are compiled in MATLAB to simulate the distortion current detection method, and the simulation results show that the method can meet the real-time and accurate requirements for the active power filer.The control method for compensation current is the key tache to accomplish the active power filter. Considering the drawbacks of the conventional PI control method for tracing the periodic changing distortion current, an improved method is proposed in this paper to improve the dynamic state and steady state performances of the system. The proposed method is the combination of fuzzy control and recursive integer PI control. A simulantion model is established using MATLAB/Simulink, and the simulation results show that the proposed method is better than the conventional PI method in performances.Otherwise, a three-phase shunt active power filter which is based on DSP controller is designed in this paper. The preliminary design of system hardware and software is presented.