The Research on H/spl infinity/ Control and Fuzzy Control in Shunt Active Power Filter

The traditional control strategy of active power filter (APF) has low accuracy and bad robustness. Firstly, a state-space model of shunt APF is established. Taking errors as unknown disturbance to the system, a robustness controller is designed based on the H_infin control theory. Secondly, the fuzzy PI control with self-adjustable factor is applied in the DC-link voltage control of APF. The self-adjustable factor regulates in the whole region according to error absolute value and the outputs are the corrections of scale factor and integrating factor. Finally, the designed H_infin controller and fuzzy controller are used in the simulation model of APF. From the simulation, it can be seen that the controller can improve the current compensation effect of APF meanwhile stabilize the DC-link voltage. Simulation results certify that the synthetical control method can improve the stability as well as the robustness of control system and the APF has better effects on the harmonic compensation.