Impedance-model-based SSR study considering DFIGs at different locations

Doubly fed induction generator (DFIG) based wind farm connected to series compensated networks will introduce sub-synchronous resonance (SSR). Most of the studies have ignored the effect of DFIGs at different locations. In this paper, a large-scale wind farm is divided into two sub wind farms, represented by two aggregated DFIGs at different locations. Impedance models of two sub wind farms and the transmission line are established and Nyquist criterion is applied to analyze the effect of DFIGs at different locations on SSR when wind speed, series compensation degrees and the parameters of converters vary. The results show that when one of the influencing factors varies, the DFIGs near the point of common coupling (PCC) have greater impact on SSR than the DFIGs far from PCC. Finally, time domain simulation is performed in PSCAD/EMTDC, which verifies the correction of the conclusion. The method this paper proposes does not need complex calculation and can judge the impact of different factors on SSR intuitively.