Certain investigations on power quality using shunt active filter configuration and FLC based current estimation techniques

Abstract

The growing number of power electronics based equipments produced an important impact on the quality of electric power supply. Both high power industrial loads and domestic loads cause harmonics in the network voltages. One of the biggest problems in power quality aspects is the harmonic contents in the electrical system. Generally, harmonics may be divided into two types, namely voltage harmonics and current harmonics. Current harmonics is usually generated by harmonics contained in power supply and depends on the type of load such as resistive load, capacitive load, and inductive load. Harmonics generated by load are caused by nonlinear operation of devices, including power converters, arc furnaces, gas discharge lighting devices, etc. Shunt Active Filter (SHAF) based SVPWM is best suited because of its ability to make source current waveforms nearly to be sinusoidal and less THD (within 5%). Since SHAF based VSI for various PWM techniques to reduce the %THD which didn t consider the variation in load current, the performance of closed loop control which takes into account the load current variations by various current estimation techniques namely p-q, d-q, SDM and PHC are compared using PI controller . Among the above, PHC using PI controller gives better performance based on %THD. Since PI controller requires precise linear mathematical models, which are difficult to obtain and may not give satisfactory performance under parameter variations, load disturbances, etc. to overcome the above difficulties, for the same current estimation techniques Fuzzy Logic Controllers (FLCs) are implemented for the improvement of source current waveforms and reduction of %THD. Fuzzy controller based PHC gives the least %THD which is in accordance with IEEE-519 standard.