特高压直流输电系统换流站故障过电压研究

Study on fault overvoltage of converter station of UHVDC power transmission system

±800 k V特高压直流输电系统换流站内电容性和电感性组件较多,在发生短路故障时容易引起过电压现象。研究各种操作和故障情况下过电压的特性,保证系统的安全稳定运行非常重要。利用PSCAD仿真软件建立了±800 k V云南—广东特高压直流输电工程的模型,在换流站内选取了换流阀阀顶对中性母线短路故障和换流变压器阀侧单相接地两种典型故障工况进行了研究。结果表明阀顶对中性母线故障时非故障极线路过电压水平较高,在上组四个换流变压器阀侧绕组中高压端Y/Y绕组端子处单相接地时的过电压水平最高。

There are many capacitive and inductive components in converter station for ± 800 k V DC power transmission system, which is easy to cause overvoltage phenomenon when a short circuit fault occurred. Research on the characteristics of overvoltage under various operation and fault conditions to ensure the system＇s safe and stable operation is very important. A simulation model of the UHVDC power transmission project from Yunnan to Guangdong is built by using PSCAD software. To carry out this research, two typical faults in convert station are chosen： the short circuit fault between the top of convert valve and neutral bus, and single-phase ground fault occurred at the side of converter transformer. Research results show that higher overvoltage appears on the non-faulty pole when short circuit fault between the top of convert valve and neutral bus; among four upper rectifier bridge side of connected winding of convert transformer, the highest overvoltage appears at upper rectifier bridge side wye-wye connected winding of convert transformer when single-phase ground fault occurred.