直流系统无功动态特性及其对受端电网暂态电压稳定的影响

摘要

对交流系统大扰动后的直流系统无功动态特性进行了深入的分析,提出了直流系统无功源-荷转换的新观点.从动态无功平衡的角度分析了直流系统无功源-荷转换对受端电网暂态电压稳定的影响机理和途径,并提出了定量刻画临界暂态电压稳定时直流系统无功动态特性的解析方法.在此基础上,综合考虑直流系统无功源-荷转换特性、无功网络传递特性和直流落点电压支撑强度,构建了一种用于评估直流系统对受端电网暂态电压稳定影响的解析指标.与临界切除时间变化量指标所得结果相比,南方电网的相关仿真结果验证了所提指标的有效性和实用性.%The dynamic characteristics of HVDC reactive power after large disturbances in AC system are thoroughly analyzed,and a new viewpoint of reactive power source-load transformation of HVDC is proposed.In the view of dynamic reactive power balance,the influence mechanism and approaches of HVDC reactive power source-load transformation on transient voltage stability of receiving-end power grid are analyzed,and an analytical method to quantitatively depict the dynamic characteristics of reactive power for HVDC in condition of stable critical transient voltage is proposed.On this basis,an analytic index to evaluate the influence of HVDC on transient voltage stability of receiving-end power grids is proposed,comprehensively considering the HVDC reactive power source-load transformation characteristics,transmission characteristics of reactive power network and voltage support strength of DC-link location.Compared with the results of critical clearing time index,simulative results of China Southern Power Grid verify the effectiveness and practicability of the proposed index.