A comparative study on SVC and STATOCM in dynamic voltage stability improvement of a system with different load characteristics

This paper presents a comparison between the dynamic performance of Static Var Compensators (SVC) and Static Synchronous Compensators (STATCOM) in improving the voltage stability of the system and reducing the post disturbance voltage recovery time. The dynamic simulation has been done on the Nordic-32 test system which mimics the characteristics of the Swedish transmission system. The simulation has been carried out using a time-domain simulation software called PSS/E. The simulation has been done while taking into account different load characteristics including induction motor loads which are prevalent in the Swedish power grid. A methodology for sizing and placement of the SVC and STATCOM has been proposed to mitigate the voltage instability of the system. It has been found that STATCOMs have shown superior performance over SVCs in improving the post-disturbance voltage recovery time and the voltage stability of the system. It has been found that the post-disturbance voltage recovery time was reduced down by 60% for the case with STATCOM while for the case with SVC, the voltage recovery time was reduced down by 26% for the same capacitive rating as that of the STATCOM ¹ .