Effect of Dynamic Voltage Restorer in Compensating for Voltage Sag and Controlling Harmonics in a Power Distribution System using Fumman Industry as a Case Study

Different power quality surveys done by researchers identify voltage sags as the most serious power quality problems for industrial customers. Voltage sag can cause serious problems to electric loads that cannot withstand variation in voltage such as adjustable speed drives, process control equipment and computers. This research work investigated the effect of Dynamic Voltage Restorer (DVR) in compensating for voltage sag and controlling harmonics in a power distribution system. A DVR is a power electronic converter base device that is used to regulate the voltage at the load terminals from various power quality problems like sag, swell unbalance etc in the supply voltage. The mathematical equations representing voltage sag and it compensation are presented. To implement the effect of DVR on industrial load network, Fumman Industry was considered as a case study. The DVR was modeled by building the subsystem of each major component. The components are injection transformer, fuzzy logic controller, battery and Pulse Width Modulation (PWM) inverter. Optimization technique was used to determine the appropriate battery size. Simulation was done without and with the DVR using Matlab/Simulink; under three and double phase line-to-ground faults.Simulation results showed that the modeled DVR can work very well against balanced and unbalanced voltage sag caused by fault in industrial distribution systemconsidering the harmonic limits