DVR Implementation for Compensation of Sag/Swell using Fuzzy Logic Controller

Voltage sag is a common and undesirable power quality phenomenon in the distribution systems which put sensitive loads under the risk. An effective solution to mitigate this phenomenon is to use dynamic voltage restorers and consequently, protect sensitive loads. The protection of the sensitive but unbalanced and/or non-linear loads from sag/swell, distortion and unbalance in supply voltage is achieved economically using a dynamic voltage restorer (DVR). Such devices are used to protect sensitive loads on distribution electrical systems, placing it in series with sensitive loads. This paper presents a DVR performance under such events, able to compensate sags/swells in two cycles. A peak detector and the in-phase compensation method are used to get quick and accurate responses. The compensating voltages when injected in series with a distribution feeder by a 3-single phase H-bridge voltage source converter (VSC) with constant switching frequency hysteresis band voltage controller, tightly regulate the voltage at load terminals against any power quality problem on the source side. A capacitor supported DVR does not need any active power during steady state operation because the injected voltage is in quadrature with the feeder current. The simulink results are been obtained through MATLAB software.