龙政直流开路试验分析

Analysis of Longzheng HVDC Open Line Test

分析了龙政直流带直流线路开路试验时,开路试验保护(电压原理)动作的原因。根据龙泉换流站的一次OLT试验数据,指出保护动作的主要原因是龙政直流输电工程采用的开路电压计算公式仅适用于触发角大于60°、没有直流线路的理想状况。在保证开路实验成功的情况下,根据实际直流工程系统绝缘要求和参数,计算出能够进行OLT试验的临界时间常数,在满足灵敏度要求条件下,整定开路试验电压原理保护的门槛值,这可以提高高压直流系统的可靠性。

This paper analyses the reason of open line voltage protection when an open line test was executed in Longzheng HVDC. The main reason is that the open line voltage formula in Longzhcng HVDC can only be applied to the ideal situation when the firing angle of the converter is less than 60° and the valve is not connected to the DC transmission line. The marginal time constant of open line test can be calculated according to the structural parameters and the insulation requirement of DC transmission line on the basis of succeed open line test. The threshold of open line voltage protection, under satisfying the sensitivity requirement, can he set which can improve the HVDC reliability.