Stability analysis for sub‐synchronous oscillations in multi‐DFIGs connected system considering the interaction between generators

Abstract

Abstract In order to reveal the multi‐DFIGs interaction mechanism in DFIG wind farms (DFIG‐WFs), this paper proposes a method based on dynamic energy flow path for stability analysis of sub‐synchronous oscillations in multi‐DFIGs connected system. First, the detailed dynamic energy model of DFIG‐WFs is established considering the inter‐DFIGs coupling effect, and the energy flow paths among multi‐DFIGs are revealed. From this, the interaction energy coefficient is defined to describe the effect of multi‐DFIGs interaction on the system stability, which can be divided into two items: the inter‐DFIGs induction coefficient and the inter‐DFIGs circulation coefficient. On this basis, how the differences in the parameters affect these coefficients are analysed. In this way, the effects of multi‐DFIGs interaction on the oscillation are clarified. Finally, a wind farm model is built in RT‐LAB for simulation verification. The results show that, the changes in DFIG parameters may have mutually exclusive effects on the two coefficients. When the parameters of DFIGs differ greatly, the circulation effect is dominant, which is mainly determined by the difference between DFIGs. If the parameters of DFIGs are similar to each other, the induction effect is dominant and the influence law of parameters is consistent with that of single equivalent model.

Keywords

• DFIG wind farm
• energy flow path
• multi‐DFIGs interaction
• subsynchronous oscillation