Application of an SVC to damp sub-synchronous interaction between wind farms and series compensated transmission lines

This paper demonstrates that wind farms connected to a grid through a series compensated transmission line may exhibit sub-synchronous oscillations. It is shown that the flux in the stator winding and the currents in the transmission line are the major participants of this mode. Dynamic Phasors are used to model the small signal model of the transmission network so that the network is accurately represented at sub-synchronous frequencies. An SVC is used to introduce damping to this oscillation mode, with line current as the feedback signal. The application is demonstrated for a large practical power system.