Design of ISOGI PLL Based Control for Power Quality Enhancement Using Custom Power Devices

Abstract

Power Quality (PQ) problems are receiving greater attention in the newlinerecent years due to considerable increase of non-linear loads such as arc newlinefurnaces, electronic ballasts, diode rectifiers and variable speed drives etc. newlineThe PQ problems are most important to consider for both electrical utility newlineand end users of electrical supply system. Power quality problems are newlinerelated to voltage across the point of common coupling (PCC) and current newlinedrawn by the loads from the AC supply mains. The PQ problems related to newlinethe voltages are sags, swells, phase jumps, harmonics, unbalance and newlineflickering etc. and the PQ problems related to current are reactive power newlineburden, harmonics, unbalance, poor power factor and voltage regulation. newlineThese PQ problems cause rotor heating, noise and vibrations in electrical newlinemachines, failure of capacitor banks, malfunctioning of relay and circuit newlinebreakers and increased losses in the distribution system. Due to these newlineproblems, PQ has become an important research in electric distribution newlineand utilization systems. newlineIn this thesis, power quality enhancement in distribution system by newlineutilizing custom power devices (CPD) using a novel control algorithm is newlinepresented. The dynamic performance of CPDs mainly depends on the newlinespeed and accuracy of phase and magnitude estimation from voltage / newlinecurrent signal. Therefore, an algorithm with accurate detection and newlinefiltering capability is required for power quality enhancement using CPDs. newlineThe main scope of the thesis is to identify a PLL for proper newlinemagnitude and phase estimation and to develop an efficient control newlinealgorithm for handling power quality issues efficiently under newlinebalanced/unbalanced grid voltage / load conditions. In order to identify newlinethe suitable PLL for power quality applications, an extensive research has newlinebeen carried out. This research work introduces an improved second order newlinegeneralized integrator (ISOGI) based phase locked loop (PLL) for the newlineestimation of phase, frequency and magnitude of voltage/current at PCC.