To explain the mechanism of sub-synchronous resonance(SSR)in doubly-fed induction generator(DFIG)based wind turbine system under series compensation

a static reference frame impedance model of DFIG based wind turbine is established. Firstly

the dq impedance model of DFIG based wind turbine is transformed into complex vector form and its frequency-domain impedance model is derived by frequency transformation. Based on the physical interpretation represented by the impedance model

the influence of controller and network parameters on equivalent impedance and SSR frequency of grid-connected system is analyzed using equivalent RLC series circuit. Damping control and virtual inductance control are proposed to mitigate SSR

which can increase the damping of SSR region and reduce the SSR frequency of the system

respectively. Finally

the accuracy of the model and theoretical analysis is verified by simulation.