基于混合式直流断路器的柔性直流电网快速重合闸策略  

Fast Reclosing Scheme for VSC-HVDC System Based on Hybrid DC Circuit Breakers

作　　者：刘天琪[1] 舒稷 王顺亮[1] LIU Tianqi;SHU Ji;WANG Shunliang(College of Electrical Engineering and Information Technology,Sichuan University,Chengdu 610025,China)

机构地区：[1]四川大学电气信息学院,成都610025

出　　处：《高电压技术》2020年第8期2635-2642,共8页High Voltage Engineering

基　　金：国家重点研发计划(2017YFB0902400).

摘　　要：基于混合式直流断路器(hybrid direct current circuit breaker,HDCCB)保护的柔性直流电网在故障清除之后,需要对故障线路进行快速重合闸操作。在直流系统被孤立的换流站重合闸于故障清除状态的故障恢复期间,会有较大的功率波动导致重合闸过程中功率恢复缓慢,不能满足直流电网快速重合闸的要求。该文首先基于HDCCB的拓扑结构提出重合闸操作时间最短的快速重合闸操作流程。然后基于直流电网的控制系统,从直流电网的故障开断过程出发,揭示了在直流电网重合闸过程中功率波动的原因,并且提出了优化之后的快速重合闸策略,以实现直流系统重合闸于故障清除状态时功率的快速恢复。利用电磁暂态仿真软件PSCAD/EMTDC搭建5端柔直系统进行仿真,结果表明所提出的快速重合闸策略能够有效地抑制孤立换流站在重合闸于故障清除状态时故障恢复过程中的功率波动,缩短重合闸恢复时间50%以上,提高直流系统的输电可靠性。The voltage-source-converter-based high-voltage direct-current(VSC-HVDC)grid based on hybrid DC circuit breaker protection needs to perform a fast reclosing operation on the faulty line after DC fault is cleared.During the fault recovery process of isolated station reclose to fault cleared state in VSC-HVDC system,there will be intense power fluctuation which will result in slow power recovery during the reclosing process,thus the requirements of DC grid fast reclosing can not be met.Firstly,based on the topology of hybrid direct current circuit breaker(HDCCB),a fast reclosing procedure with a minimum operation time is proposed in this paper.Furthermore,based on the control system and the fault interruption process of VSC-HVDC grid,the cause of power fluctuation during the reclosing process is revealed.Then an optimized fast reclosing strategy is proposed to realize a fast fault recovery process when the VSC-HVDC system is reclosed to the fault cleared state.To verify the validity of the proposal,a five-terminal VSC-HVDC grid with the optimized fast reclosing strategy is built and simulated in PSCAD/EMTDC.The simulation results show the proposed fast reclosing strategy can effectively suppress the power fluctuation during the reclosing process,and can shorten the reclosing recovery time by more than 50%,thus the reliability of DC grid can be improved.

关 键 词：柔性直流电网 直流断路器 功率波动 快速重合闸策略 故障恢复 直流电网可靠性 

分 类 号：TM732[电气工程—电力系统及自动化]