基于桥臂阻尼阀组的模块化多电平换流器故障快速清除与系统恢复技术

Fast fault clearance and system recovery technology of MMC based on bridge-arm damping valve groups

针对柔性直流故障快速清除与系统快速恢复技术难题,介绍了基于桥臂阻尼阀组的故障快速清除与系统恢复技术方案。在分析柔性直流双极短路和桥臂短路2种故障机理的基础上,提出适用于工程的桥臂阻尼阀组的具体电气拓扑和阻尼阀组的控制保护策略以及桥臂阻尼参数的选取原则和工程参数设计流程。以某多端柔性直流输电工程为例进行了仿真验证,仿真结果表明,在直流双极短路故障条件下,所提方案可加快直流短路电流的衰减,实现故障清除后系统快速重启动;在桥臂短路条件下,所提方案可加速阀侧交流电流中直流分量的衰减,加快交流开关的开断过程,降低了换流阀故障损坏的风险。仿真结果验证了所提方案的有效性和可行性。

The scheme based on the bridge-arm damping valve groups is introduced to solve the technical problems of flexible HVDC fast fault clearance and system recovery. Based on the mechanism analysis of flexible HVDC pole-to- pole short circuit fault and bridge-arm short circuit fault, the specific electrical topology of the bridge-arm damping valve groups available for engineering, the control and protection strategy of damping valve groups, the selection prin- ciple of bridge-arm damping parameters and the design process of engineering parameters are proposed. A multi-ter- minal flexible-HVDC project is taken for example, and its simulative results show that, when the flexible HVDC pole- to-pole short circuit fault occurs, the proposed scheme can accelerate the attenuation of the DC short circuit current and realize fast restart of system after the fault clearance, and when the bridge-arm short circuit fault occurs, the pro- posed scheme can accelerate the attenuation of the DC component in the valve-side AC current,accelerate the brea- king process of AC switches and reduce the failure risk of converter valves. The effectiveness and feasibility of the proposed scheme are verified.