Damping enhancement of multimachine power system through STATCOM control

A static synchronous compensator (STATCOM) is a shunt connected FACTS device, which is capable of enhancing the power system damping by exchanging reactive power with the system. In this thesis, robust STATCOM controls have been investigated for power system damping improvement. Non-linear and linear models of a single machine infinite bus (SMIB) system as well as multimachine systems installed with STATCOM have been derived. The method of multiplicative uncertainty has been employed in the robust design to model the variations of the operating points. A graphical method termed as loop-shaping is used to select a suitable open loop-transfer function from which the robust controller is constructed. Improvement in the graphical method is proposed by embedding a computational technique called the particle swarm optimization (PSO) in the original loop-shaping method. The high order multimachine models have been simplified for control design through model reduction techniques. Linear and non-linear models of both single machine as well as multimachine system have been simulated including the PSO embedded robust controllers. A four machine test system is used to test controllers considering small as well as large disturbances including three phase symmetrical faults. Results indicate that the proposed robust design provides extremely good damping over a wide range of operating conditions.