Application Of CDEGS Software In Power System

This thesis does detailed simulation research on the electromagnetic environment of UHV transmission lines and voltage sharing problems of ground grid in substation, utilizing Canadian SES's CDEGS software package.The electromagnetic parameter of power transmission include: electrical field, magnetic field, radio inference (RI) and audible noise (AN). With Enviro module of CDEGS software, this thesis makes detail simulation research on the four electromagnetic parameter of UHV AC and DC transmission lines. The influence of the height of phase conductors, wire spacing, diameter of the subconductor and the weather on the above parameters are analyzed. The simulation results show that, raising the wire height, reducing the wire spacing, increasing the subconductor diameter can effectively improve the electromagnetic environment around UHV transmission lines.To better solve the hidden danger in the substation caused by the non-uniform surface potential distribution when short-circuits fault occurring, this thesis, using Malz module of CDEGS, analyzes the influence of the injecting point of short-circuit current, vertical ground rods, soil resistivity, grid corner using circular arc, level extending earth wires, laying high resistivity materials and fence location on the surface step voltage. Through the analysis following conclusions are made: the maximum step voltage is 20% larger when short-circuit current flows into the grounding conductor at the substation corner than when the current injecting to the substation center. A linear relationship was found between step voltage and soil resistivity. Grounding grid with unequal spacing can decrease the maximum surface step voltage very effectively. Vertical ground rod has little effect on the step voltage. Arc grid corner can effectively lower step voltage of the corner zone. Level extending earth wires at arc grid corner can reduce step voltage at the corner, but they will increase the surface step voltage at its outer place. High resistivity surface layer can improve substation grounding network security. Reasonable distance between the fence and grounding grid edge can effectively decrease the step voltage at the substation corners.