±800kV云广直流输电线路保护的仿真及分析

Simulation and Analyses for Yun-Guang 800 kV HVDC Transmission Line Protection System

建立包含控制系统阀控制层的±800kV云广直流输电系统仿真模型,对其以电量变化率为基础的行波保护作为主保护、电流差动保护作为后备保护的直流输电线路保护进行仿真,全面检测其保护动作特性。分析指出:电压变化率判据往往无法检出高阻接地故障,且受雷击干扰、冲击电晕和谐波的影响;电流差动保护是针对直流线路高阻故障的后备保护,它采用线路两侧电流差值的幅值为动作量,为避开区外交流侧故障和采样数据波动,最长延时会达到1.1s,在此阶段若阀组保护动作,将导致该极停运。建议采用"保护原理冗余"设计,即配置2套可互为补充的不同原理的保护系统。

The traveling wave protection based on the change rate of electrical quantities is used as 800 kV DC line main protection of Yunguang high voltage direct current（HVDC） transmission line,and current differential protection is used as its backup protection.The Yunguang HVDC transmission system model with the control system was built.A large of simulations were carried out to check the performance of Yunguang HVDC transmission protection.The results show that it＇s difficult to detect high impedance ground faults for the voltage change rate criterion and the performance of the criterion will be influenced by lightning interference,pulse corona and harmonics.Current differential protection is the backup protection for high impedance faults and use the amplitude of the differential current as operation current.In order to stay away from the faults at AC side and various interferences in data sampling,the longest time delay of the differential protection may be 1.1 s.During this period,the operation of valve protection may result in the corresponding pole out of service.The ＂protection principle redundancy＂ design is recommended in which two sets of protections with different principles can complement each other.