Optimal control of SVC for subsynchronous resonance stability in typical power system

In recent years, subsynchronous resonance (SSR) has been an important problem in power systems. SSR is caused by the electrical resonance of the synchronous generator and capacitor-compensated transmission lines. The life of a turbine-generator shaft will be terminated when this oscillation occurs and causes serious shaft damage. To prevent SSR and to protect the system, many control devices for SSR have been developed. In this paper, the authors try to damp SSR by optimal control of SVC in the first benchmark model of the IEEE system. The system will be linearized and its state space will be obtained. When the eigenvalues of the system shift to the left of imaginary axis, the system stability will be obtained. To demonstrate the effectiveness of the proposed optimal control, time domain simulations are also performed on the first benchmark model with Matlab Simulink. The results show that optimal control can better damp SSR than the PID controller and, because of the small control signal, system saturation is prevented with optimal control