基于可控有源振荡换流的混合式高压直流断路器

Hybrid HVDC Circuit Breaker Based on Controllable Active Oscillation Commutation

直流断路器是最大程度地保障柔性直流电网系统健全和持续可靠运行的关键装备。为降低预充电系统耐压要求,耦合负压换流型混合式直流断路器需额外配置换流变压器,这严重限制了其在高压直流输电领域的应用。结合耦合负压换流型混合式直流断路器和电容可控振荡换流原理,提出了一种基于可控有源振荡换流的模块级联混合式高压直流断路器。在保障故障电流双向阻断的前提下,所提断路器不但可降低预充电系统的耐压要求,而且可有效减小研制成本和占地面积。首先研究了可控有源振荡电路拓扑结构和工作原理;其次,提出了可控有源振荡换流型混合式直流断路器拓扑,分析了其故障电流分断工作原理;然后,揭示了电容、电感等元件参数对断路器分断性能的影响机理,确定了可控有源振荡电路的元件选型方法;最后,仿真验证与性能对比分析表明:所提可控有源振荡换流型混合式直流断路器原理可行,技术经济性能优越。

DC circuit breaker is the key equipment to ensure the sound and reliable operation of VSC-based DC grids.To reduce the withstand voltage requirements of pre-charge system,the hybrid DC circuit breaker(HDCB)based on coupled negative voltage commutation needs to be equipped with additional commutation AC transformer,which seriously restricts its application in HVDC transmission.To solve this problem,an HDCB commutated by the controllable active oscillation circuit(CAOC-HDCB)is proposed in this paper.On the premise of guaranteeing the bidirectional blocking capability of fault current,the proposed CAOC-HDCB can not only reduce the withstand voltage requirements of pre-charge system,but also effectively cut down the development cost and footprint.Firstly,topology and its operation principle of the CAOC are studied.Next,topology of the CAOC-HDCB is proposed;meanwhile,its operation principle is analyzed in detail.Then,influencing mechanism of component parameters on the performance of CAOC-HDCB is revealed,and the corresponding components selection method is determined.Finally,the simulation results and performance comparison analysis show that the principle of the proposed CAOC-HDCB is feasible and the technicality and economy are superior.