Dynamic performance of statcom under line to ground faults in power system

Reactive power control through the static compensator (STATCOM) has gain wide attentions due to its outstanding performance. The STATCOM based on voltage source converter (VSC) is used for voltage regulation in transmission and distribution systems. It can supply dynamic VAR´s during system faults for voltage support. The STATCOM operation can be adversely affected to voltage source converter (VSC) over-currents and trips, during power system faults when its VAR support functionality is most required. In this paper, we develop an STATCOM with “emergency PWM” strategy in the VSC during and after system faults. Adopting PWM technique results in high switching losses but strict requirement of STATCOM with PWM (pulse width modulation) for VSC based STATCOM avoid total system loss. This constraint of developing VSC with PWM functionality results in avoiding over- currents and trips of the STATCOM during and after system faults, and ensures that the STATCOM functionality improved a lot by supplying required VAR support when it is most required. The Simulation results are shown for a 48-pulse VSC based ± 100 MVAR STATCOM connected to a 2-bus power system. Simulation results validate the “emergency PWM” strategy to prevent VSC over-currents and to supply required reactive power under line to ground system faults.