Robust Shunt FACTS Controller Design for Power System Damping Improvement

This paper presents a design of robust PID controller structure for shunt FACTS controllers namely STATCOM and SVC. Robust STATCOM and SVC is designed using H-infinity loop-shaping technique. The performance of the controller is tested in single machine infinite bus power system to damp out the oscillations. The variation of transmission line reactances is considered as multiplicative uncertainty and the design is carried out by applying robustness criteria to improve both stability and performance. The performance of robust controller is compared with conventional PID controller in damping out the oscillations. It has been observed that the conventional PID controller is ineffective at operating points other than nominal. The robust design provides an extremely good damping characteristic over a range of operating conditions and it is evaluated based on the time domain specifications