Performance of Static VAR Compensator for Changes in Voltage Due to Sag and Swell

The deviations that occur in electrical power supplied by utilities to end users result in voltage decrease termed as sag and increase termed as swell. Due to voltage variations, change is evident for a short duration in voltage, current or frequency. In order to maintain constant voltage to the connected load, compensation devices are used based on flexible AC transmission systems (FACTS) technology. Based on an increase or decrease in voltage, suitable correction action can be taken by power electronic-based devices. The performance of static VAR compensator (SVC), which is a shunt connected FACTS device, is analyzed for voltage sag and swell. The SVC controller scheme, reactive power generated or absorbed, firing pulse generation and modes of SVC operation in MATLAB/Simulink environment are explained.