Comparison of controllers for power quality improvement employing shunt active filter

In this paper, an implementation of shunt active filter for current harmonics compensation in order to achieve power quality improvement under non linear load condition is proposed. Shunt active filter makes the source current almost sinusoidal under non linear load condition by eliminating current harmonics. Controller generates the reference current and it is compared with actual current. PWM current controller controls the switch of the shunt active filter circuit. Shunt active filter eliminates the undesired current harmonics by injecting current into the system thereby reduces total harmonic distortion and improves power factor. The main objective of the project is to find the most suitable control method that is capable of reducing total harmonic distortion in the source current under non linear load condition. Fast and precise control loop is needed in order to assure the desired power quality. Three control techniques have been proposed: PI controller, Hysteresis current controller, Fuzzy logic controller. The system is modelled using Matlab/Simulink and simulation results prove that the source current harmonics can be reduced and power factor can be improved. The comparitive performance of the proposed three controllers is also presented.