HVDC换相失败典型暂态响应特性及其抑制措施

以CIGRE第一标准模型为研究对象,分析了交流系统发生各种故障时可能引发的换相失败,即不对称故障相相连的逆变器的上下2个换流阀最易发生换相失败,对称故障则依情况而定。基于电力系统电磁暂态仿真工具PSCAD/EMTDC对其发生常见故障时典型暂态响应过程进行详细的仿真分析与计算,据此提出了一些发生换相失败故障时通过控制模式的转换抑制其危害及恢复系统运行的举措,如逆变器一次换相失败故障可以通过改变换流器触发脉冲的次序以控制换相失败发展过程,避免发生更为严重的换相失败;对于2次换相失败,应投入包括最后一个开通阀在内的旁通对,以减少因故障而使换流变压器造成直流偏磁。

Typical transient response of HVDC commutation failure and its countermeasures

Possible commutation failures during different HVDC transmission system faults are analyzed with the CIGRE HVDC benchmark model as an research object. For an asymmetrical fault, commutation failure appears normally between the top and bottom transistors connecting faulty phase, while for a symmetrical fault,it depends on the situations. Typical transient responses during some general faults are simulated with PSCAD / ETMDC. Countermeasures are presented to limit the impact of commutation failure and recover system operation:for the first commutation failure,change the order of firing pulse to control the developing process of commutation failure;for the second commutation failure,put the side devices into operation,including the last running transistor to reduce the influence on transformer.