Ground Potential Distribution Of HVDC Ground Electrode Considering Tectonics

As there is strong direct current injecting into the earth for HVDC to operate on ground-between return status, the potential on the surface would change widely and produce unfavorable effects on the AC systems around. At the same time, there would be electromagnetic effect where the grounding electode locates, such as step voltage and contact potential. In this case, the electrical parameter of the grounding electode should satisfy certain requirements, and the key to solve the problem is to discover the rules for the current in the earth.This paper takes finite element analysis into the calculation of the ground current field, and deduces the formulas for calculating the voltaic field of the dc ground electrode on the basis of the complex tectonic.Then we build a typical soil model and a accurate multi-layer soil model using Anays. A comparison is made between typical and multi-layer soil models of the earthy characters and ESP.The simulation result show that, the ground resistance and the step voltage around the site are much affected by the soil resistivity where the grounding locates. While the ESP, which is within the range of tens of meters, is affected by the deep soil resistivity. After that, this paper calculates the ESP for the situation where lake, ocean, river, mountain exists and analyses the effects of the geotectonic. Finally, this paper draws a conclusion for the distribution law of the ESP consider different influencing factors when the dc-ground electrode operates an ground-between return status. The lakes and the rivers would change the distribution of the potential slightly. The existence of the ocean medium makes a drop far away, so that it would make a general drop for the whole ground, and makes a rise for the earth potential near the ocean. Making proper use of the characteristics of the ESP could solve the problems brought by Direct current injecting into the earth.