高压直流系统接地极电流的影响及抑制措施研究综述及展望

Review and Prospect on Influence of Grounding Electrode Current in HVDC System and Its Suppression Method

高压直流系统采用单极大地回路方式运行时,上千安培的直流电流流入大地,当直流电流流过交流系统的变压器中性点时引起直流偏磁,并导致地电位抬升、金属构件腐蚀等问题。对此,国内外开展了接地极注入直流电流的影响及抑制措施的研究。在介绍交流系统中性点电流产生机理及其危害的基础上,重点综述了接地极电流引起的地表电位及地中电流分布的研究现状,总结了格林函数法和微分方程法2种地表电位分布的计算方法,分析了地表电位及地中直流电流分布的影响因素,进而归纳了目前国内外广泛采用的电阻型、电容型、补偿型等中性点电流抑制措施,介绍了相应装置的工作原理及设计方案等,同时对现有研究存在的不足和未来研究方向进行了分析和展望。

When HVDC system works as monopole ground return mode, the grounding electrode will inject the DC current of more than 1000 A into ground, which will cause the DC current flowing through the grounded natural point of transformer in AC system. The DC current will form return circuit via AC power equipment and transmission lines, which will lead to the DC bias of the transformer, rising of ground potential, corrosion of metal components and etc. To solve the problems presented above, the researches on the influence of grounding electrode current and its suppression method in HVDC System are carried out at home and abroad. After introducing the generation mechanism of the current flowing through natural point in ac system and its damage, this paper reviews the research status on the distribution of ground surface potential and underground current caused by the grounded electrode current, summarizes respectively the methods for calculating the ground surface potential based on Green function and differential equation, and analyzes the factors influencing the distribution of the ground surface potential and underground DC current. And then, the paper summarizes the methods used at home and abroad to suppress the current flowing through natural point based on resistive, capacitive and compensating principles, and introduces the working principles and design schemes of suppression installations. At last, the paper analyzes the shortcomings of present research and looks forward to future study trends.