三峡－上海直流输电工程控制保护功能的完善

简述了三峡至上海直流输电工程的系统调试过程，分析了宜都站直流场大地/金属转换开关的保护功能，并提出了修改建议；研究了其直流线路保护、极母线差动保护和中性母线差动保护，给出了直流线路人工短路接地故障试验结论；分析了换流站辅助电源丢失试验结果，分析了试验过程中双极中性母线差动保护误动的原因，提出了改进措施并付诸实施。以上几个技术问题的解决，完善了该工程的控制保护功能，保证了该工程的顺利投运。

Completion of Control and Protection Functions in 3GS HVDC Project System Commissioning Test

The commissioning test procedure of the HVDC power transmission project from the Three Gorges Hydropower Station to China that interconnects Central China Power Grid with East China Power Grid is described in brief. The protective function of metallic return transfer breaker (MRTB) installed in DC site of Yidu converter station is analyzed.Some suggestions to the improvement of MRTB protection to perfect the protective function of MRTB are proposed. The DC transmission line protection, the DC pole bus differential protection and DC neutral bus differential protection are researched and the conclusion of artificial grounding fault of DC transmission line is given. The test results on losing substation auxiliary power supply as well as the reason causing maloperation of DC bipolar neutral bus differential protection during the test are analyzed, and corresponding improving measures are put forward. By means of solving above-mentioned technical problems, the control and protection functions of the Three Gorges to Shanghai (abbr. 3GS) HVDC interconnection project is completed and the accomplishment of the system commissioning test as well as putting the 3GS project into operation are ensured.