一种新型限流型高压直流断路器拓扑

New Topology of Current Limiting High Voltage DC Circuit Breaker

随着柔性直流输电技术的不断成熟,直流输电变得越发普及,而高压直流断路器作为直流输电系统的关键部分,其重要性不言而喻。针对现有高压直流断路器存在故障时短路电流大、分断速度慢、避雷器吸收能量过高等问题,提出了一种具有限流能力的新型高压直流断路器拓扑,该拓扑在传统直流断路器换流支路基础上增加了H型桥限流部分,利用平波电抗器与限流部分共同限流,可以显著降低故障时电流的上升速率与峰值。文中详细说明了新型拓扑的基本工作原理,对故障分断过程进行理论分析并给出相关参数的影响关系及选取依据,通过搭建基于Pscad/Emtdc仿真软件的新型限流型断路器模型,与已有限流型断路器方案相比,避雷器能量吸收降低了62.8%,故障分断时间减少了0.8 ms,并具有良好的可靠性与经济性,仿真结果验证了所提新型限流型直流断路器拓扑可适用于当前柔性直流电网。

With the continuous maturity of flexible DC transmission technology,DC transmission becomes more and more popular and the importance of HVDC circuit breaker,as a key part of DC transmission system,is self-evident.In view of such problems as high short-circuit current in the fault,slow breaking speed and excessive high energy absorption of arrester of existing high-voltage DC circuit breaker,a new topology of high-voltage DC circuit breaker with current-limiting capability is proposed.The current limiting part of type H bridge is added in the topology on the basis of converting branch of traditional DC circuit breaker.The use of smoothing reactor and the current-limiting part to limit current together,which can significantly reduce the rate of rise and peak of current in fault.In this paper,the basic working principle of the new topology is explained in detail,the fault breaking process is analyzed theoretically,and the influence relationship and selection basis of relevant parameters are given.By setting up a new current-limiting circuit breaker model based on Pscad/Emtdc simulation software and comparing with the existed current-limiting circuit breaker scheme,the energy absorption of arrester is reduced by 62.8%,the fault breaking time is reduced by 0.8 ms,both with good reliability and economic effect.The simulation results verify that the proposed new current limiting DC circuit breaker topology can be applied to the current flexible DC power grid.