多端柔性直流配网过电压防护方案对过电流影响研究

Research on Overvoltage Protection Scheme of Multi-Terminal DC Distribution System and Its Impact on Overcurrent

多端柔性直流配网因其技术优势逐渐成为国内外研究热点,典型故障中的过电压和过电流及防护方法研究是其关键技术之一。针对±10 kV三端柔性直流配网开展了典型故障下过电压和过电流仿真分析,提出了三端柔性直流配网避雷器配置方案,并分析了在未配置和配置避雷器两种情况下过电流产生差异及根本原因。首先,针对某三端柔性直流配电系统,开展了典型故障工况、过电流决定性故障工况的理论分析;其次,基于PSCAD/EMTDC建立了三端柔性直流配电系统的电磁暂态仿真分析模型,仿真分析了典型故障下的过电压和过电流,提出了系统关键位置的最大过电压和过电流水平;最后,基于仿真结果提出系统避雷器配置方案,并在系统配置避雷器情况下开展了典型故障的过电流仿真分析,分析系统在配置与未配置避雷器情况下过电流的差异及影响因素,提出过电流最严重的故障工况。研究结果可为多端柔性直流系统故障下过电流防护措施、故障清除方案研究以及设备选型提供参考。

Multi-terminal DC distribution system has gradually become a research focus at home and abroad due to its technical advantages. The study of overvoltage and overcurrent as well as their protection methods in typical faults are the key technologies. In this paper,the simulation analysis of overvoltage and overcurrent under typical faults are carried out for ± 10 kV three-terminal DC distribution system and the configuration scheme of arrester is proposed. The difference of overcurrent in the case of unconfigured and configured arresters are analyzed. Firstly,for a three-terminal DC distribution system,theoretical analysis of typical fault conditions and overcurrent decisive fault conditions is carried out. Secondly,based on PSCAD/EMTDC,the simulation analysis model of three-terminal DC distribution system is established. The overvoltage and overcurrent under typical faults are simulated analysis,and the maximum overvoltage and overcurrent levels at key positions of the system are proposed. Finally,based on the simulation results,the configuration scheme of arrester is proposed,and the overcurrent simulation analysis of typical faults is carried out when the system is equipped with the arrester. The differences and influencing factors of the overcurrent between the system unconfigured and configured the arrester are analyzed,and put forward the most serious fault conditions. The research results can provide reference for overcurrent protection measures,fault isolation schemes and equipment selection under multi-terminal DC system faults.