Power System Damping Improvement by Robust STATCOM Voltage Controller Design Using Loop-Shaping Technique

This paper presents a robust Static Synchronous Compensator voltage controller design for power system damping. The method of multiplicative uncertainty has been employed to model the variations of the transmission line reactances. The design is carried out applying robustness criteria for improving stability and performance. A loop-shaping technique has been employed to select a suitable open-loop transfer function, from which the robust controller function is constructed. The controller is tested for a number of disturbances. The damping provided by the robust controller is compared with a fixed-parameter PID controller, whose gains were calculated through a pole-placement technique. It has been observed that the PID control is ineffective at operating points other than nominal. The robust design has been demonstrated to provide extremely good damping characteristics over a range of operating conditions. Here the H∞ loop shaping technique is applied to design robust STATCOM controller. The designed robust STATCOM controller is implemented in Single Machine Infinite Bus power system. Simulation results are compared with conventional PID controller and robust H∞ loop shaping STATCOM controller in a SMIB system to show that the improved and robustness of robust loop shaping STATCOM controller proposed over the conventional PID controller in settling the system operating in same conditions.