Emulational Research On The Current Distribution Of DC Electrode In HVDC Power System

There will be relatively large currents which are long-term dispersed by the grounding electrode in bipolar HVDC transmission line in a unipolar operation. To avoid the local overheating of soil near the grounding electrode, the currents dispersed by grounding are required to be distributed uniformly as possible. The calculation and analysis on current field of DC grounding electrode with all kinds of forms and layout (including surface current distribution of grounding electrodes), is a very important problem in the design of DC ground electrode.A numerical calculation method on DC ground current distribution problems is presented in the thesis. The mirror image method is introduced firstly, which is used to solve the soil nonuniformity problem in current field analysis, and the method is the basis of DC ground electrode current field calculation as well. Several models in the DC ground electrode analysis are introduced secondly, which are used to solve the issue of the simulation current selection in current field analysis. After simulation and comparison of several line current models and circle current models, a programmable equipotential line current model which gives attention to both calculation accuracy and operation speed is presented and programmed, and the computational results are in good agreement with those got from domestic and foreign researchers. A further analysis on current field distribution of the cirque DC ground electrode is produced based on programming ideas. Meanwhile the burying depth characteristics in different situations and the issue of grounding resistances in double layer soil are studied and compared.Both the influence of vertical ground electrode burying depth on grounding resistances, and the distribution of ground current in the double layer soil, are emulated and analyzed in the thesis. At the same time, under the UHV transmission environment and parameters, the current spill of double cirque and the current field distribution of double cirque in unequal burying depths are studied. A principle analysis on the assumption is produced finally,giving some suggestion to the layout mode of HVDC multi cirque DC grounding electrode in future.