应对直流电源丢失问题的中压变电站二次系统性能提升方案及远方冗余保护新判据研究

Research on Performance Improvement Strategy of Secondary System and Novel Criterion of Remote Redundancy Protection Coping With DC Power Loss within MV Substation

我国对中压变电站每个间隔一般只配备一套保护系统,采用保护测控一体化设计,且多套保护共用一套直流系统。则当保护用直流电源丢失后,所关联的多个间隔将同时失去对应的保护功能。此时一旦发生故障,只能依靠远后备保护进行故障切除,带来故障影响范围过大以及故障切除动作时间过长的问题。为此,该文提出两种高性价比的中压变电站二次系统性能提升方案,为实施基于远方跳闸的单元式线路远方主保护奠定物质基础。在此基础上,提出完全不依赖多端数据同步对时、基于补偿电压模量比较的远方冗余保护实用化新判据,以有效应对保护用直流电源的丢失问题。理论分析与仿真结果表明,所提保护新判据无需严格多端数据的同步,且覆盖区域内部分数据不完整或暂时不可达时也有望实现快速的选择性保护。此外,判据具有较高的灵敏度,与原有距离I段保护共同组成的应急主保护能有效覆盖线路大部分故障,其选择性及动作速度均高于距离II段保护。

In China, each primary device is generally equipped with one set of protection system within MV substation. The protection and measurement and control device is designed with integration, and each set of DC system is shared by multiple sets of protection. When a protective DC power is lost, multiple primary devices relevant to the DC power will lose the corresponding protective function at the same time. Once a fault occurs, only the remote back-up protection could be relied on to trip the fault, leading to the problem of large scope of fault influence and long time of fault tripping. This paper proposed two kinds of cost efficient performance improvement strategies of secondary system within MV substation, which could lay the foundation of unit line remote main protection based on remote tripping. Then, a novel practical criterion for remote redundancy protection based on compensation voltage modulus comparison was proposed to cope with protective DC power loss, which could be independent of multi-terminal data synchronization. Theoretical analysis and simulation result indicate that the proposed criterion is expected to realize fast selective protection when partial data are incomplete or not available, and the synchronization of multi-terminal data is not required.In addition, the emergency main protection composed of the original zone I distance protection and the proposed criterion with high sensitivity could cope with most line fault effectively, the selectivity and speed of which are better than that of zone II distance protection.