POWER QUALITY IMPROVEMENT USING FLC BASED UPQC

Pratik Das

Abstract


ABSTRACT

Any electrical power system consists of wide range of electrical, electronic and power electronic equipment in commercial and industrial applications. The quality of the power is effected by many factors like harmonic contamination, due to the increment of non-linear loads, such as large thyristor power converters, rectifiers, voltage and current flickering due to arc in arc furnaces, sag and swell due to the switching of the loads etc.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.

These problems are partially solved with the help of LC passive filters. However, this kind of filter cannot solve random variation in the load current wave form and voltage wave form. Active filters can resolve this problem. However, the cost of active filters is high. They are difficult to implement in large scale.  Additionally, they also present lower efficiency than shunt passive filters. One of the many solutions is the use of a combined system of shunt and active series filters like unified power quality conditioner which aims at achieving a low cost under highly effective control.

The Unified Power Quality Conditioner (UPQC) device combines a shunt active filter together with a series active filter in a back-to-back configuration, to simultaneously compensate the supply voltage and the load current or 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 study the compensation principle and different control strategies used here are based on Fuzzy Logic based controller of the UPQC in detail. The control strategies are modeled using MATLAB/SIMULINK. The performance is also observed under influence of utility side disturbances such as harmonics, flicker and spikes. The simulation results are listed in comparison of different control strategies and for the verification of results.


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