采用直流断路器的对称单极多端柔性直流故障清除策略

针对直流断路器应用中直流线路故障快速选择性隔离问题,研究了对称单极多端柔性直流线路故障清除策略。根据对多端直流系统的单极和双极接地故障特性的分析结果,得到了单极和双极故障初期相同的故障电流上升率余弦特性衰减特性。提出了基于电流变化率的方向纵联选线策略,同时设计了采用直流断路器策略实现故障隔离和重合闸的直流线路故障清除方案。通过搭建的PSCAD/EMTDC模型,对单极接地故障时的电流上升率特性和设计的直流线路故障清除策略进行了验证,仿真结果证明了电流上升率特性的正确性以及所述故障清除策略的有效性。

Fault Elimination Strategy of Symmetric Single-pole VSC-MTDC Based on DC Circuit Breaker

Aiming at the fast selective isolation problem of direct current(DC)line fault in DC circuit breaker application, the fault elimination strategy of symmetric single-pole voltage source converter based multi-terminal direct current(VSC-MTDC)transmission line is studied. The characteristics of single-pole-to-ground fault and pole-to-pole fault are analyzed, and the same cosine attenuation characteristics of the fault current changing rate in the early stage of single-pole-to-ground fault and pole-to-pole fault are obtained. A directional line selection strategy based on current changing rate, and the scheme for fault isolation and fault elimination using DC circuit breaker and reclosing strategy are designed respectively. The characteristic of fault current changing rate in the single-pole-to-ground fault and DC fault elimination strategy are verified based on PSCAD/EMTDC. Simulation results demonstrate the validity of the current changing rate characteristic and the effectiveness of the designed strategy for the elimination of the fault.