Alterable integral control algorithm for shunt active power filter

The pollution of harmonics in power system becomes serious because of power electronic devices used widely. As an important device to eliminate the pollution, Active power filter (APF) becomes more popular. The result of i_p i_q harmonics current detection method based on instantaneous reactive power theory is the sum of all harmonics current. But sometimes it is not necessary. In response to the problem, a detection algorithm for specified harmonic current is presented in this paper. The tracking accuracy can´t meet the requirements when the parameters of PID controller are invariable, An alterable integral PI control algorithm is analyzed in the shunt APF in this paper. The model of three-phase shunt APF based on the two methods is built in Matlab/Simulink, and the simulation results used the two kinds of PI algorithms are shown.