MITIGATION OF VOLTAGE SAGS AND SWELLS PROBLEM USING DYNAMIC VOLTAGE RESTORER WITH FUZZY LOGIC CONTROLLER BASED ON A BI DIRECTIONAL H-BRIDGE AC/AC CONVERTER (CASE STUDY: ARBAMINCH TOWN DISTRIBUTION NETWORK)

Abstract

Voltage sag and swell is one of the common Power quality problems in Ethiopian Distribution system. The same problem is occurring in Arbaminch Distribution system abruptly. Due to this sensitive electronics equipment‟s are burning in Arbaminch frequently. While measuring the voltages in Arbaminch Distribution mainly in Secha feeder 55% sag and 45% swell has been recorded. One of the solutions to the aforementioned issue is the dynamic voltage restorer (DVR). DVR is the most practical and cost-effective options for reducing voltage sag and swell. Fuzzy Logic is used to control the DVR quickly, and two modes of operation for controlling voltage sag and swell are used to control the AC/AC converter. When grid power enters at a voltage that is less than to 220Vr.m.s, a voltage sag mode takes place, and when it enters at a voltage that is higher than to 220Vr.m.s, a voltage swell mode takes place. The sag is improved near to 96% and swell is also improved near to 96% by the DVR controlled with fuzzy logic controller. The whole simulation is carried out in MATLAB/Simulink.