Performance Analysis of Universal Power Quality Conditioner Systems Based on Seven-level NPC Inverter Using PD-SPWM with Fuzzy Control Scheme

Abstract

This paper presents novel Unified Power Quality Conditioner (UPQC) system based on seven-level Neutral Point Clamped (NPC) inverter using combined PD-SPWM and fuzzy control scheme. The proposed UPQC is adopted to mitigate source current harmonics and compensate all voltage disturbances simultaneously. It is designed by the combination of series and shunt Active Filters (AFs) connected by a common DC link capacitor. The DC voltage at common DC bus is maintained constant using proportional integral voltage controller. The Synchronous Reference Frame (SRF) method is used to get the shunt APF reference signals and the power reactive theory (P-Q theory) for the series APF. Conventional control schemes require complex calculations, the use of intelligent systems help to reduce the control system size and the operation complexity. The shunt and series Active Power Filter (APF) reference signals derived from the control algorithm are injected in Fuzzy intelligent controllers to generate switching signals. The functionality of proposed UPQC system and its control system is evaluated using Matlab-Simulink software and SimPowerSystem Toolbox under various operation conditions in cases of most common power quality problems such as voltage sag, voltage swell, current harmonic compensation of nonlinear loads and unbalanced load. The simulation results show UPQC performances to improve the power quality in steady and transient conditions operation at the point of common coupling on power distribution under unbalanced and distorted voltage conditions.