【摘要】 在特高压直流线路的送、受端,与换流站配套的接地极承担着单极运行时形成大地回路的电极作用,其选址、设计对整个线路的安全运行极其重要。接地极的设计包括接地电阻、跨步电压等计算均需要准确可信的地层电阻率资料。特别是在锦屏-苏南线路同里换流站庙泾接地极及溪洛渡-浙西金华换流站金丝接地极单极运行引起附近变电站偏磁报警事件之后,对接地极深部(地下50 km)地层电阻率的测试尤显重要。针对设计方的要求,根据几种物探方法的应用条件及其主要的优势、劣势,提出了一套测试方法的组合,即用常规对称四极了解极环埋深处(地下3~4 m)和300 m以浅地层的电阻率分层,用可控源声频大地电磁(CSAMT)了解300 m~3 km地层电阻率,用大地电磁(MT)了解3~50 km地层电阻率。实践证明该方法组合既很好满足了设计需求,也具有较好经济性和可操作性,可以在一定范围内推广。更多还原

【Abstract】 An earth electrode helps to make up the current circuit in the earth when the transmission line works with single phase, so it plays an important role in the safe operation of the transmission line. The accurate and reliable data on soil resistivity data is required for design and calculation of an earth electrode. Especially, after the magnetic biasing alarm events of Xiluodu-Zhexi ±800 kV UHVDC project and Jinping-Sunan±800 kV UHVDC project, dependable data of soil resistivitybecomes more and more important. To provide parameter values for designer, we put forward a combination of geophysics methods based on the analysis of the advantages and disadvantages of those methods. The main idea of the combination is using symmetric quadrupole sounding method for prospecting the electrical distribution of 300 m deep rock and soil mass, using CSAMT for 3000 m depth prospecting, and using MT for 3 km ~ 50 km depth prospecting. We applied the combination to several UHVDC projects. The combination’s operability and effectiveness are tested in practice, meanwhile it is relatively economic.更多还原