直流输电工程大地回线和金属回线转换过程及运行实例分析

Analysis and Case Study of Transfer between Ground Return and Metallic Return in the HVDC Project

笔者主要以贵广二回直流工程为例,首先介绍了大地回线和金属回线的转换原理及其过程,其次介绍了在调试和运行过程中导致大地回线和金属回线转换不成功的运行实例,然后分析了直流保护逻辑存在的缺陷所导致的金属回线向大地回线转换时MRTB、MRS频繁分合的情况。笔者就这一情况提出了相应的保护逻辑修改方法,并发现保护逻辑经修改后,金属回线/大地回线转换正常,在系统调试和实际运行中不再出现MRTB、MRS频繁分合的情况。

Taking the Gui-Guang Ⅱ HVDC Project as example, this paper introduces both the principle and the process of the transfer between ground return and metallic return, discusses a case of unsuccessful transfer between GR and MR in this project, and analyzes the frequent switching on/off of the MRTB/MRS due to DC protection logic bugs during the transfer from MR to GR. Therefore, an approach to modify the DC protection logic is proposed. After the modification, the transfer between MR and GR becomes normal without frequent switching on/off of the MRTB/MRS during commissioning and operation of the HVDC system.