Study On Method Of Grounding Resistance Measurement With Short Electrode Wire And DC Grounding

Grounding system is important to the reliable operation of power system and the safety guarantee of person and equipment. Grounding resistance is the key parameter of grounding system, the measurement of grounding resistance is an crucial step to make sure the grounding system to play its role during the system fault, it should be carried out before the power plant or the substation is launched or annually during their operation. The method for grounding resistance measurement used now needs long current electrode wire, which needs more work in wire layout and it is really a trouble in metropolitans to find path for wires, the induction between wires can bring error in too. So it is very meaningful in both theory and application aspects to research the theory foundation and the measuring electrodes configuration of grounding resistance measurement and its applicability. At the same time, problems of the DC grounding system are valuable because it is not only significant in HVDC operation but also affects the AC system nearby.As the main work of this paper, method of grounding resistance measurement with short electrode wire is researched from its theory, calculation model to electrodes configuration, error of the method is discussed thoroughly. For DC grounding, leaking current and earth surface potential distribution of three kinds frequently used DC grounding electrodes are calculated, problem of DC current through neutral point of AC transformer is discussed.Method of grounding resistance measurement with short electrode wire should be based on the compensate principle of fall of potential method, the secondary segment method is selected as the calculation model to calculate the compensating points. The secondary segment method is improved and enhanced in both function and accuracy.Numerical programs are coded for dividing conductor, leaking current and earth surface potential distribution calculation, the exact location of compensating points is calculated, the relationship between them and parameters of grid is studied, the results are proved to be acceptable by field measurements reported in other papers.