基于直流电抗器电压曼哈顿距离的单端保护方案

Single-Ended Protection Scheme Based on Manhattan Distance of DC Reactor Voltage

高阻故障降低直流线路主保护的灵敏性和可靠性,严重影响了系统的安全性。为解决这一问题,进一步提高保护的可靠性,提出一种基于直流电抗器电压曼哈顿距离的单端保护新原理。首先,分析了高阻故障影响保护选择性的原因,揭示了现有基于直流电抗器电压保护原理的不足。然后,通过分析直流电抗器电压的暂态特性及直流电抗器的阻碍作用,阐述了区内、外故障时直流电抗器电压波形存在差异性的原因,并引入曼哈顿距离描述这种差异性,借此提出一种基于直流电抗器电压曼哈顿距离的整体保护方案。该方案只需测量单侧直流电抗器电压便可进行故障检测,易于实现且经济性好。最后,在PSCAD中搭建直流输电系统模型,验证了所提单端保护方案的有效性和优越性。

High-resistance faults reduce the sensitivity and reliability of the main protection of flexible DC lines, and seriously affect the safety of the system. In order to solve this problem and further improve the reliability of the protection, this paper proposes a new principle of single-ended protection based on the DC reactor voltage Manhattan distance. Firstly, the reasons for high resistance fault to affect the protection selectivity are analyzed, and the shortcomings of the existing DC reactor voltage protection principle are revealed. Then, by analyzing the transient characteristics of the DC reactor voltage and the blocking effect of the DC reactor, the reasons for the difference in the voltage waveform of the DC reactor during the internal and external faults are explained, and the Manhattan distance is introduced to describe this difference. In this way, an overall protection scheme based on DC reactor voltage Manhattan distance is proposed. This scheme can detect faults only by measuring single-ended DC reactor voltage, which is easy to implement and has good economic efficiency. Finally, a DC transmission system model is built in PSCAD to verify the feasibility and superiority of the protection scheme.