采用直流系统准稳态模型解析故障后高压直流输电系统无功的时域变化规律， 并通过仿真深入分析其动态变化幅值和时间特性． 通过对比分析考虑直流影响和不考虑 直流影响两种情况，阐述了故障后直流系统无功动态对感应电动机无功恢复产生的延缓 效应，揭示了直流系统无功动态影响暂态电压稳定的机理和途径． 最后提出以感应电动机 临界滑差变化率作为评估直流系统对暂态电压稳定影响的指标，并结合南方电网实际系 统进行了验证．

In this paper,first,the post-fault HVDC ( High-Voltage Direct Current Transmission) reactive power change laws in time domain are analyzed by using the quasi-steady model of HVDC system.Next,the amplitude and time features of reactive power change are explored through simulation.Then,by comparatively analyzing the reactive power change with or without HVDC,the reactive power recovery delaying effect that HVDC reactive power dynamics exert on the induction motor is illustrated,and the mechanism and pathway by which HVDC reactive power dynamics influence the short-term voltage stability are explored.Finally,an index,namely the change rate of critical slip of induction motor,is proposed to evaluate the influence of HVDC reactive power dynamics on the short-term voltage stability,and the effectiveness of the proposed method is verified by an application example on China Southern Power Grid.