Fuzzy Logic Controller for Three-Level Shunt Active Filter to Mitigate Current Harmonics with Neutral Point Voltage Unbalances Control

Abstract

This paper presents a three-phase three-level (NPC) shunt active filter controlled by fuzzy logic current controller to mitigate current harmonics. Shunt active filter is the best solution to eliminate harmonics drawn from nonlinear load especially for low power system. For the medium power applications three-level inverter is more used, their advantages are reduction of the harmonic content and diminution the semiconductors voltage or current ratings. The compensation currents adopted a synchronous reference frame detection method that gives good performances under ideal or non ideal voltage conditions. To maintain dc link voltage constant and compensate the power losses of the inverter a proportional-integral voltage controller is used in the outer control loop. To perform output voltage delivered by the inverter another controller is added in inner control loop for balancing neutral point voltage. The simulation is performed using Matlab-Simulink and Simpowersystem Toolbox. The obtained results show the effectiveness of the proposed controller scheme.