Effect of Coke Bed on the Electrical Performance of HVDC Ground Electrode

To prevent the high voltage direct current ground electrode from eroding, it is usually wrapped by a coke bed, which may affect the electrical performance of the electrode, such as current distribution and step voltage. In this paper, the effect is analyzed by a numerical method, which couples moment method with circuit theory by regarding the coke bed as several resistors connecting the ground electrode with soil. The method is simple and efficient. The calculated results are in good agreement with the measured ones. The current distribution, ground resistance. and step voltage of several typical electrodes with and without coke beds are calculated. The effect of the coke bed on the above parameters is summed up.