基于注入法的改进特高压直流接地极引线保护方法

目前，特高压直流输电系统通常采用基于注入法的接地极引线保护。文中分析了传统接地极引线保护方法的特性，并在此基础上提出了一种改进接地极引线保护方法。改进保护方法包括主保护和后备保护。主保护采用高频测量阻抗横差构造单回线故障保护判据，仅利用单侧电气量，不依赖于通信；后备保护利用接地极引线末端电流方向构造保护判据，对通信的同步性与实时性要求较低。以某实际运行的±800 kV特高压直流系统为例，利用PSCAD/EMTDC对所提保护方法进行仿真验证。仿真结果表明所提改进保护方法的主保护较传统保护方法可极大缩小保护死区，在后备保护的配合下可实现全线保护。

An Improved Protection Method of Grounding Electrode Line for UHVDC Based on Injection Method

At present, ultra-high voltage direct current(UHVDC)transmission system usually adopts grounding electrode line protection based on injection method. Based on the analysis of the characteristics of traditional protection methods, an improved grounding electrode line protection method is proposed. The improved protection method includes main protection and backup protection. The main protection uses transverse difference of high frequency measurement impedance to construct the protection criterion for single circuit fault, which only uses electrical quantity of one side and does not depend on communication. The backup protection uses the current direction at the end of grounding electrode line to construct protection criteria, which requires less synchronization and real-time communication. Taking an actual ±800 kV UHVDC system as an example, a simulation model is built using PSCAD/EMTDC to verify the proposed protection method. The simulation results show that the main protection of the improved protection method can greatly reduce the dead zone of protection compared with the traditional protection method, and can achieve full-line protection with the cooperation of backup protection.