An adaptive algorithm for controlling reactive power compensation in active power filters

Shunt active power filters (APFs) can be used to compensate both harmonics and reactive powers from nonlinear loads. However, due to the limitation of the APF output current, the harmonics cannot be compensated successfully if the required compensating current is higher than a certain level. To overcome this problem, the paper proposed an adaptive algorithm for controlling reactive power generated by the APF. This control algorithm will permit the APF to fully compensate both harmonic and reactive currents if the total compensation demand is within the APF capacity. When a high level of compensation current is required, the reactive power generation will be reduced to save the APF capacity for the harmonic compensation task. The implementation of the adaptive algorithm with different types of APF controller is also discussed. Performances of APFs with and without the adaptive algorithm are simulated and compared to show the validity of the proposed approach.