HVDC换流阀桥臂短路电流耐受分析

Short Circuit Current Withstand Analysis of HVDC Converter Valve

提出一种高压直流(HVDC)输电换流阀短路电流仿真模型和晶闸管承受短路电流的结温预测方法,可证明换流阀晶闸管在系统最大短路电流工况下的耐受能力。分析换流阀桥臂短路原理,得出短路电流计算方法,通过基于PSCAD/EMTDC的6脉动换流阀桥臂短路电流仿真,获得短路电流、暂态电压、恢复时间等关键参数,结合晶闸管瞬态热阻,采用数据拟合与迭代法,实现晶闸管在短路电流下结温曲线的预测,进而得出晶闸管承受阀桥臂短路电流后的暂态电压耐受能力。试验结果表明该方法有较高的可靠性。

A short circuit current simulation model of the high voltage direct current(HVDC) transmission converter valve and a junction temperature prediction method for the thyristor withstand short circuit current are presented,which can prove the ability of the converter valve thyristor under the maximum short circuit current of the system.The short circuit principle of the bridge arm of the converter valve is analyzed and obtain the calculation method of shortcircuit current.Through the simulation of the short circuit current of the six-pulse converter valve arm based on PSCAD/EMTDC,key parameters such as short circuit current,transient voltage and recovery lime are obtained.Combined with the transient thermal resistance of the thyristor,data fitting and iterative methods are used to predict the junction temperature curve of the thyristor under short circuit current,and then the transient voltage tolerance of the thyristor after the short circuit current of the valve bridge arm is obtained.Experimental results show that the method has high reliability.