特高压直流单换流器退出引起过压问题的分析及优化

Analysis and Optimization of Overvoltages in UHVDC Project Caused by Exiting of Converter

换流器投退是特高压直流输电工程的关键技术之一,在站间通信故障的情况下整流侧一台换流器因故障退出可能会导致本极另一台运行换流器的过压问题,使过压保护动作最终闭锁该极。本文以滇西北—广东±800k V特高压输电工程为参照对象,从控制策略的角度分析了不同工况下过压问题的成因,并提出了针对性的优化策略,通过在整流侧短时调整电压参考值,在逆变侧短时调整电流裕度,有效抑制了站间通信故障情况下整流侧故障退出换流器造成的过压问题。借助实时数字仿真仪(RTDS)仿真系统,验证了该控制策略的有效性,对后续的特高压工程具有参考价值。

The entrance/exiting of converter is one of the key techniques of UHVDC project. When teleeonmmnication between stations is lost, the exiting of one converter at rectifier side due to fault sometimes would cause overvoltages of the rest converter in series. In this paper, the overvoltages are analyzed from the perspective of control strategy and an optimized strategy, which adjusts the voltage reference at rectifier side and current margin at inverter side respectively, is purposed. The real time digital simulator （RTDS） simulation results prove that the optimized strategy can effectively suppress the overvoltages under the circumstances mentioned above and can be adopted in future UHVDC projects.