The existing operation experiences indicate that subsynchronous resonance (SSR) may occur in wind farms which are connected to series compensated systems. Hence

it is necessary to analyze the mechanism of SSR in wind farms

which will contribute to the solutions. Firstly

an equivalent system model for the analysis of SSR is established based on the real parameters of a wind farm in China. The SSR phenomenon of this model is presented by time domain simulation. The impacts on SSR from the factors such as wind speed

number of generators

and control parameters of doubly-fed induction generators (DFIGs) are checked using eigenvalue analysis. An equivalent circuit is deduced for the mechanism analysis of SSR. Based on this circuit

the mechanism of SSR impacts from aforementioned factors are analyzed in details. Considering all the analysis

it is pointed out that the SSR phenomenon of wind farms is a special electrical resonance

and nothing to do with the generator shaft. Solutions of SSR in wind farm are also proposed and are verified by simulations and eigenvalue analysis.