短路比指标在多直流馈入电网中的应用分析

Analysis of Short Circuit Ratio Index Application in Multi-Infeed-HVDC Grid

目前,高压直流输电已经成为我国大区互联和远距离大容量输电的重要形式,其中以广东的直流落点为最甚,多个直流逆变站之间的电气距离非常接近,给电网的安全运行增加了很多潜在的风险。本文以南方电网为研究对象,研究有多回直流馈入的广东电网各个换流母线的电压支撑能力。本文研究了各种短路比指标与直流闭锁前后受端系统的稳态电压支撑能力间是否存在定量的关系。短路比指标中的两个因素分别是短路容量和直流功率,因此利用BPA进行仿真时,不断调整电网的线路长度和直流功率,以研究短路容量和直流功率对受端系统的电压跌落水平的影响。本文在进行直流闭锁后受端换流母线稳态电压跌落时,同时保留不同的直流线路和直流回数来调整仿真模型,以研究直流回数对受端电压稳定性的影响。

At present, HVDC has been the important form in the wide interconnected area and Large-capacity、long-distance transmission. The most number of the HVDC infeed has been formed in Guangdong Power Grid among South China Grid. The electric distance between DC inverter stations very closely and increase a lot of potential risk. South China Power Grid is used as the testing model in the paper, the voltage supporting ability of commutation bus in the multi-HVDC-infeed Guang Dong Power Grid is studied. SCRs are studied to make out if they have relationship with the voltage supporting strength of commutation bus before and after the DC latching fault. In SCR Index, there are two factors which are capacity of short circuit and HVDC power. As the BPA has been used to emulate, line＇s length and the DC power continuously are adjusted to research the effect on the voltage stability of the receiving grid by the capacity of short circuit and HVDC power. As the static voltage drop level under DC and AC failure are emulated, different HVDC lines have been retained to adjust model, the effect on the voltage stability by different numbers of HVDC has been found out.