Study On Three Phase Shunt Voltage Active Power Filter

As an ideal device to eliminate harmonic current and improve power factor, active power filter can compensate the harmonic and reactive power with variable both of frequency and amplitude, and it makes up the drawback of the passive power filter. Therefore, the development of active power filter is rapidly studied and has been applied in practice in some developed countries. Nowadays, in China, the exploitation of active power filter is at the stage of experiment and high power products have not been used up to now yet, so the research of active power filter has very important significance.The thesis mainly considers three-phase shunt voltage active power filter.The two key technologies are harmonic and reactive currents detection, and compensation currents control.Exact and real-time detection of the instantaneous variable harmonic and reactive current in power system is the premise for compensation of active power filter. At present, there are many detection methods concerning harmonic and reactive current, in which, the method based on instantaneous reactive power theory is used widely in three-phase system than others, and it consists of p-q detection method applied to symmetry power system without distortion, i_p-i_q detection method and d-q detection method applied to asymmetry distortion power system.Control method for compensation current is the key tache to accomplish the various functions of active power filter, and it controls active power filter to establish the anticipative compensation current. Compared to traditional triangular wave compare control method and hysteresis current control method, voltage space vectors PWM control method has the high compensation precision and rapid response speed. In addition, the control method can be accomplished with algorithm and need not analog control circuit such as hysteresis compare circuit, so it is very convenient to be accomplished with digital method. As the rapid development of Digital Signal Processing technology, the control methodusing voltage space vectors PWM algorithm accomplished by DSP is discussed as a recommendable method and to be of extensive development potential.At last, the thesis simulates the three-phase shunt voltage active power filter system using SimpowerSystems Blockset in MATLAB6.5/SIMULINK in order to not only validate the correction and performance of different detection and control methods, but understand principle of active power filter deeply as well.