Simulation And Research On Current Detecting And Controlling Approaches Of Active Power Filter

For the wide application of the nonlinear loads and all kinds of converter equipments making the power system polluted with a mass of harmonic current, it is urgent to eliminate harmonic and improve power quality. The application of instantaneous reactive power theory provides the effective method of detecting harmonic current; and for the inherent shortcomings of LC filters and the development of power electronic technology, it is being an important way to eliminate harmonic dynamically by active power filters. In china, the studies and exploitations in active power filter is at its beginning stage, and large capacity mature producis have not been coming out yet, so the studies in active power filers have important significance.The two keys of harmonic current detecting and current tracking controlling have a great impact on the performance of active power filters. Therefore, this paper discusses the harmonic and reactive current detecting method based on the instantaneous reactive power theory and presents the harmonic and reactivecurrent detecting method based the ip - iq algorithm used in three-phasethree-wire circuits and three-phase four-wire circuits. The mathematics analysis and the simulation results examine the feasibility and validity of the current detecting method. Moreover, this paper puts forward the improved schemes of the two main current controlling methods: the improved triangle-wave linear current controlling method and the hysteresis current vector controlling method. The feasibility and superiority of the two improved current controlling methods is examined by dynamic simulation and theoretical analysis.To examine the validity of the controlling system of the shunt active power filter and understand the controlling rules furthermore, this paper simulates the shunt active power filter system with SimPowerSystems Blockset in MATLAB/SIMULINK. The simulating results show that the two improvedcurrent controlling methods can filter a majority of the load harmonic current, and they have superiorities to the traditional methods: reducing the capacity and the power loss of the active power filter easily; and decreasing the switching frequency within the controlling precision to improve the performance of the active filter.The studies in this paper have some guidance on the exploitation of the active power filter experimental system.