Nonlinear Variable Gain fuzzy with Enhanced PLL BasedModified SRF ApproachforUPQC

Abstract

This paper proposed nonlinear variable gain fuzzy (NVGF) through enhanced phase-locked loop (EPLL)with modified synchronous reference frame(MSRF) approach for 3-phase, 3-wire unified power quality conditioner (UPQC) for compensation of current and voltage harmonics, voltage swell/sag and unbalance in the distributed power system. NVGF utilizes Takagi-sugenofuzzy (TSF) rule base for controlling the dc-linkage capacitor voltage of UPQC, which limits the dc-linkage voltage deviations throughout the load and source voltage disturbances and assures a small steady-state error. The current and voltage references of UPQC are obtained using MSRF with EPLL technique. The EPLL synchronization method considers negative-feedback in the inner loop of conventional PLL, which provides insensitivity to noise, higher degree of immunity to distortion and eliminates other type of contaminations existing in the signal. The efficiency of the control system is evaluated through comparison with standard PI-control and then validated using real-time Opal-RT hardware supported by suitable results for verification.