直流接地极极址勘测的研究

Research of DC ground electrode site survey

直流工程建设初期,直流接地极的选址合理性会影响交流电网的直流偏磁状况。针对典型土壤,从直流电流透深以及直流偏磁计算的角度,研究了直流接地极极址勘测时的测量范围以及测量深度。在运用大地电磁(MT)法进行直流接地极勘测时,推荐测量范围为待选极址周围70 km;测量深度推荐值为70 km,测量深度必须穿过高阻层,直到电阻率下降到临界电阻率以下,否则会给直流接地极评估带来显著误差。同时给出了MT法的测量点布置方法。

The reasonability of DC ground electrode site survey at the early stage of DC power transmission project will affect the DC bias condition of AC power grid. The measuring range and depth of DC ground electrode site survey is studied in the view of DC current penetration depth and DC bias calculation for the typical soil structure. When MT（Magneto Telluric） method is adopted in the DC ground electrode site survey,the recommended measuring range is 70 km around the DC ground electrode and the recommended measuring depth is 70 km,which must be beyond the high-resistance layer until the resistivity drops below the critical value,otherwise the significant error will seriously influence the evaluation of DC ground electrode site. Meanwhile,the measuring point arrangement of MT method is given.