Voltage Three-phase Parallel Active Power Filter

The paper does the theoretical study of this problem which Shunt Active power Filter (Shunt APF) based on the modern power electronic technology compensates the harmonics and reactive current of the distributing system. Several detection methods are compared, dq method based on Park is taken as the detection method of the system, and an improved harmonic detecting method is presented on the basis of the convention dq method, the detection system is made a closed loop system by it. The characters of the improved detection method are: the simple structure of hardware, low cost, high detection and reducing the influence of main parameters to detection accuracy.Some kinds of controlling methods applied by Shunt APF are particularly stated. The advantages and disadvantages of controlling methods in the practical use are pointed out. The second method is taken as the controlling method of Shunt APF. The hardware and software based on DSP TMS320F240 for Shunt Active Power Filter was presented.The detecting method and controlling method of APF are simulated by MATLAB, The simulation results are presented to conform the effectiveness of the APF which can effectually compensates the harmonics and reactive current of the distributing system.