The Research Of A Practical Hybrid Active Power Filter

With development of modern industry, more and more power electronic equipment are used in power system, resulting in increasingly severe harmonic pollution. Harmonic becomes main factors affecting power quality. Active power filter, as the most effective method to eliminate harmonic, has been paid more and more attention recently.A practical series-shunt hybrid active power filter based on fundamental magnetic potential self-balance is introduced. The current converter which is connected in series between the power utility and harmonic-producing loads will present low reactance to fundamental and the high impedance to the harmonics automatically. In the same time, the harmonic voltage drop which is produced when the surplus harmonic current flows through the current converter is detected out timely. The active power filter is controlled as a harmonic voltage source which is in proportion to the measured harmonic voltage waveform. Where, the active power filter is connected to the passive filters in series through an isolation transformer. Then the harmonic current that flows into the power system will be less. In this paper, the configuration, working principle and performance analysis of the proposed hybrid active power filter are given out. In this paper, the output voltage characteristic of a novel hybrid active power filter is analysed. The course of charge and discharge of dc side capacitive for the inverter is researched. These research results explain that active power filter takes on a small quantity of fundamental voltage. In this paper, the rating of a practical hybrid active power filter is particular analyzed。Through analyzing equivalent circuit of load harmonic current,power grid harmonic,fundamental current, rating computation formula of hybrid active power filter is given out.An experimental prototype is developed. The validity of the theory are verified by an experimental prototype. The experiment results indicate that the proposed series-shunt hybrid has excellent compensation characteristics .Experimental results indicate the LC passive filter takes on 98.86% fundamental voltage and the active power filter takes on a small quantity of fundamental voltage. Experimental results and theoretical analysis is accordant. Accordingly the rating of active power filter is sharply minished.