张北柔性直流输电工程接地系统监测技术研究

Study on Monitoring Technology of Grounding System in Zhangbei Flexible DC Transmission Project

摘要:

文中介绍了张北柔性直流输电工程主回路结构、运行方式、接地极及其作用并阐明了作为接地极的接地电阻的重要性。针对接地极可能出现的故障，研究分析了可以采取的实时监测方法；比较了电压电流法和注入法的差异，并说明张北柔性直流工程采用注入法的原因和优势；分析了注入信号频率的选择依据，并根据张北柔性直流工程的系统特性、参数，选配满足注入法原理对应的一次设备以及监测回路结构组成。通过理论分析与系统仿真试验，验证了有无阻波器对主系统的影响；最后，确定了张北柔性直流输电工程接地极在线监测的技术方案。

Abstract:

The main circuit structure, operation mode, grounding electrode and its function of Zhangbei flexible DC transmission project are introduced, and the importance of grounding resistance as grounding electrode is described. Aiming at the possible faults of grounding electrode, the adopted real time monitoring methods are studied and analyzed. The differences between voltage and current method and injection method are compared, and the reasons and advantages using injection method for Zhangbei flexible DC project are also explained. The selection basis of injection signal frequency is analyzed. According to the system characteristics and parameters of Zhangbei flexible DC project, the primary equipment and the structure of monitoring circuit are selected to meet the injection principle. Through the theoretical analysis and system simulation test, the influence of wave trap coil or not on main system is verified. Finally, the technical scheme of on line monitoring of grounding electrode in Zhangbei flexible DC project is determined.