分体式能量耗散的直流线路故障快速隔离

A Fast Fault Isolation Method for DC Transmission Lines Based on Distributed Energy Dissipation

混合式直流断路器(HDCCB)是目前实现直流电网故障隔离的可靠方法之一。然而,现有HDCCB普遍存在金属氧化物避雷器(MOV)耗能水平过高,故障隔离速度不足的问题。为此,该文提出一种分体式能量耗散的直流线路故障快速隔离方法,以传统混合式直流断路器拓扑结构为基础,增加一条旁路耗能支路(耗能支路2),可通过直流断路器耗能支路(耗能支路1)快速耗散少部分能量以实现直流故障隔离,而后通过旁路耗能支路耗散直流电抗器和直流线路中的剩余能量。相比传统方案,该方案可大幅缩短故障隔离时间,从而减少电源馈入直流电网中的能量,有效降低单次故障隔离中的总耗能水平,同时采用分体式能量耗散结构可显著降低MOV的耗能水平以及并联支数,有助于动态均流。该文详细分析了该方案的工作原理及控制策略,并与现有方案进行了经济技术性对比,最终通过仿真验证了该方案的有效性。

Hybrid DC circuit breaker(HDCCB)is the primary scheme for DC grid fault isolation.However,the existing HDCCB has the problem of high energy absorption and insufficient fault isolation speed.In view of the above problems,A fast fault isolation method for DC transmission lines based on distributed energy dissipation was proposed,which is based on the topology of traditional HDCCB,and add a bypass energy dissipation branch(energy dissipation branch 2).In this method,a small part of energy can be dissipated quickly by the energy dissipation branch of DCCB(energy dissipation branch 1)to realize DC fault isolation firstly,and then the residual energy of DC reactor and the DC line can be dissipated by the bypass energy dissipation branch.The scheme can greatly shorten the fault isolation time,thus reducing the energy fed into the DC power grid by power supply,and effectively reduce the total energy consumption level in single fault isolation.At the same time,the distributed energy dissipation structure can significantly reduce the level of energy absorption and the parallel branches of metal oxide varistor(MOV),and contribute to dynamic current sharing.In this paper,the working principle and control strategy of the scheme were analyzed in detail,and compared with the existing schemes in economy and technology.Finally,the feasibility and effectiveness of the scheme were validated by the simulation.