Study Of Hybrid-shunt Active Power Filter

Active power filter (APF) is considered as the most effective method to harness the serious "power pollution". It is a developmental tendency of utilizing APF compensating harmonic current and idle-current. In order to minimize the capability and production costs of APF, a novel topology of shunt-hybrid active power filter is put forward.First, the paper researches impedance character of LC passive filter and the influence for reactive power. And deduces parameters of LC passive filter. Then it introduces working principle of APF. It analyses compensation characteristics of APF to different types of harmonic sources, and draw a conclusion that the shunt APF fits for compensating current type of harmonic sources.Based on the analysis of various harmonic detection methods, we put stress ondiscussing the i_p -i_q detecting method on the basis of instantaneous reactive powertheory, and find the bigger detecting error of fundamental active and fundamental reactive currents in the case of unsymmetrical three-phase voltage. An improvedi_p-i_q detecting method is presented in allusion to the limitation. Simulation resultsshow that the improved i_p-i_q detecting method can eliminate error.A novel optimal voltage hysteresis current control technique is used in the hybrid-shunt active power filter. Overcoming the defect of common hysteresiscurrent control, its notable strongpoint is that it avoids the complicated calculation and unnecessary switching of voltage source inverter by identifying the locations of reference voltage vector and current error vector to control the filter's outputs. It is fast and accurate and improves greatly the performance of hybrid-shunt active power filter. So the frequency of switch is reduced and wastage is decreased.At last the components of the system are modeled and simulated with MAT LAB software. The simulation results indicate that the hybrid-shunt system have good compensating characteristic. At the same time, because the active power filter of hybrid system doesn't stand fundamental voltage, the capacity of active power filter can be reduced, and production costs are reduced.