Improvement of power quality using custom power devices

Abstract

The Power Quality Analysis aspires to bring out electricity consumers for improved power quality with application of power electronics. The research work involves in-depth analysis of the interaction among loads, power networks and various power quality improvement devices. It ultimately leads to better design of mitigation devices like Dynamic Voltage Restorer (DVR), Distribution Static Synchronous Compensator (DSTATCOM) and Unified Power Quality Conditioner (UPQC) to alleviate various power quality related problems. The main objective of this thesis is to develop a model of DVR, DSTATCOM and UPQC for enhancement of power qualityDVR is one of the custom power devices that are used as an effective solution for the protection of sensitive loads against voltage disturbances in power distribution system. The efficiency of the DVR depends on the performance of the control technique, which involved in switching the inverters. The hysteresis voltage control has a very fast response, simple operation and variable switching frequency. The validity of the proposed method and achievement of the desired compensation are confirmed by the results of the simulation in Matlab/ Simulink. newlineWhile compensating, the transient response of the DSTATCOM is very important for nonlinearly varying and unbalanced loads. The DC Link voltage is increased above the reference value when the load is suddenly removed and it is decreased below its reference valuewhen the load is suddenly increased. Conventionally, a Proportional Integral (PI) controller is used to maintain the DC Link voltage at the reference value. A fast acting DC Link voltage controller based on the energy of a DC Link capacitor is proposed. The transient response of this controller is very faster than compared to that of the conventional DC Link voltage controller. The Fuzzy Logic Controller (FLC) based DSTATCOM has been implemented and it has been verified that its transient response is better than the PI Controller response.