云广特高压直流输电负极运行换相失败及控制研究

Commutation failure of Yun-Guang UHVDC transmission system running in negative pole state and its control measures

总结直流输电换相失败的判断标准,研究防止继发性换相失败的控制措施。以云广±800 kV特高压直流输电负极运行为研究对象,利用输电系统实际参数在PSCAD/EMTDC上建立仿真模型,仿真结果表明:减小变压器变比,逆变器不发生换相失败,当增大变比到3.52时,逆变器发生换相失败;三相对称接地短路故障时换相失败对于故障合闸角没有敏感性,两相短路和单相接地短路在故障合闸角为90°和270°时最容易引发逆变器换相失败;接地电阻的大小和故障持续时间对换相失败影响很大。

The causes of commutation failure in UHVDC transmission system are analysed,its criterion is summarized and the control measures against the consequential commutation failure are studied.The simulation model of Yun-Guang ± 800 kV UHVDC transmission system with its actual parameters is built on PSCAD / EMTDC.The simulative results show that,the decrease of transformer ratio will not induce the commutation failure of inverter while its increase up to 3.52 will do;the commutation failure is not sensitive to the fault close angle for symmetrical three-phase grounding fault while it is sensitive to the fault close angle for two-phase short circuit fault and single-phase grounding fault,and the commutation failure occurs easily when the fault close angle is 90° or 270°;the grounding resistance and fault duration time have great influence on commutation failure.