Role of Pi and Fuzzy Controllers in Unified Power Quality Conditioner

Any electrical power system consists of wide range of electrical, electronic and power electronic equipment in commercial and industrial applications. Since most of the electronic equipment is nonlinear in nature these will induce harmonics in the system, which affect the sensitive loads to be fed from the system. One among the many compensating devices is Unified Power Quality Conditioner (UPQC) which specifically aims at the integration of series-active and shuntactive power filters to mitigate any type of voltage and current fluctuations and power factor correction in a power distribution network, such that improved power quality can be made available at the point of common coupling. The present work discusses the compensation principle and different control strategies (PI, FUZZY) of the UPQC in detail. The control strategies are modeled using MATLAB/SIMULINK. The performance of UPQC is examined by considering, a thyristor rectifier feeding an RL load (non linear load) that acts as a source of harmonics, to the system of concern. The performance is also observed under influence of utility side disturbances such as sag, swell, flicker and spikes. The simulation results are listed in comparison of different control strategies and for the verification of results.