Analysis of PR controller for eliminating double frequency oscillations in DC-link of 3-Ф shunt APF during source disturbances

Shunt active power filter is widely used in modern electrical distribution system and it needs an accurate control algorithm that provides robust performance under source and load unbalances. During source voltage disturbances, the presence of negative sequence component in the source current causes significant double frequency oscillations in the dc-link and it can lead to deterioration of dc-link capacitor. Proportional-Resonant (PR) controllers are attracted an increase in interest due to its superior performance over the traditional Proportional Integral (PI) controllers, when regulating sinusoidal signals. This paper presents a control scheme based on Proportional Resonant (PR) controller to eliminate such oscillations in order to keep the ripple free constant dc-link voltage under source disturbances. Further, the higher order harmonics presents in the source current are compensated using PR controller and are discussed in the paper. The studied system is modeled and simulated in MATLAB-Simulink environment for effectiveness of the study.