风电机组接入LCC-HVDC系统下的故障穿越期间电压稳定与支撑研究

Wind generation is required to provide dynamic voltage support (DVS) during fault ride-through (FRT) to enhance system voltage stability. However, DVS causes the FRT behavior of wind generation to be segmented, and its impact on voltage stability in the wind farm (WF) integrated line-commutated converter-based high-voltage direct current (LCC-HVDC) sending-end system remains unclear. To achieve a quantitative analysis to this gap, a novel quasi-static piecewise model for the sending-end system is developed, in which the segmented FRT behavior of WF is fully incorporated. Beyond the well-known saddle-node bifurcation (SNB), a new FRT-induced non-smooth bifurcation (FRTNB), is identified. The influence of WF and the LCC-HVDC system on both SNB-related and FRTNB-related voltage stability is thoroughly analyzed. Based on the acquired insights, a control strategy is proposed for the LCC-HVDC system to proactively utilize its DVS capability, which is adaptive to the segmented FRT behavior of WF and can effectively enhance system voltage stability without requiring knowledge of grid parameters. Dynamic simulations validate the theoretical analysis and the effectiveness of the proposed method under both voltage sag and swell conditions.