INTELLIGENT CONTROL OF THREE PHASE SHUNT ACTIVE FILTER

Abstract

The widespread use of power electronics in all types of industrial, commercial and even residential electrical equipment is causing the deterioration of the quality of the electric supply through distortion of the supply voltage. This has led to the development or more stringent requirements regarding harmonic current generation, as are found in standards such as IEEE-519. Passive filters have been used to limit the flow of harmonic currents , in distribution systems. However, these tend to be bulky and the design is complex, particularly if the number of harmonic components to be reduced increases. With improvements in power electronic devices and conversion techniques, an innovative concept, the active power filter, has been proposed and investigated. The PI model may seem to be simple and economical for a set of designed PI parameters and the harmonic compensation achieved by the active power filter and the response to step change in load is satisfactory, but a tendency to overshoot the set value still exists, while compensating large errors. Practically, the fine tuning of PI parameters is mostly accomplished by trial and error, which is a time-consuming process. Hence fuzzy control scheme was proposed to develop a reliable auto tuning method in order to automate the process. In this thesis, shunt active power filter for a three phase three wire system using do voltage control method is developed. The designed filter has the objective to eliminate the load generated harmonics, hence it does not require a PLL circuit. In this for controlling DC voltage PI control and intelligent control techniques are used. Comparison in power quality improvement by using PI and Intelligent controller are presented.