Sub-synchronous resonance damping in series compensated transmission lines using a statcom in the common bus

Sub-synchronous resonance (SSR) oscillations in long transmission lines may cause failure of the turbine shaft if not damped properly. The main purpose of this research work is damping SSR in series compensated transmission lines which are connected to a common bus using a STATCOM. To reach this goal, a control system is proposed and designed for a STATCOM in the transformer bus (or common bus) based on the speed deviation damping signal. In addition to SSR damping, the STATCOM, which is implemented in the transformer bus, can improve voltage stability and dynamical events such as power oscillations and first swing stability. Eigenvalue analyses and nonlinear simulations in PSCAD/EMTDC software are employed to illustrate the performance of the proposed controller and the STATCOM. Simulation results approve the proposed scheme capability in SSR damping at different level of series compensations of the transmission lines.