Evaluation For Large Grounding Grid Of 500kV Substation

This paper based on the field measuring data of 500kV Luodong Substation's grounding grid,analyze and calculate the soil resistivity, impedance ground, shunt fraction of ground wire, touch voltage and step voltage, earth potential rise and electromotive force on-net of the grounding grid;analyze the thunderbolt transient characteristic about lightning surge characteristics,attack earth potential rise,attack touch voltage and step voltage and so on;analye the influence about equalizing characteristic of large grounding grid by decanting point of short-circuit current, soil resistivity, grid spacing, vertical grounding body, circle-arc corner, level extension line,position of enclosure;research the validity to reduce the earth resistance of grounding grid by vertical grounding body in large grounding grid,analyze the reduced flow resistance action about the vertical grounding body drived into the crossing of every equalizing belt in grounding grid and the vertical grounding body drived into grounding grid all around;research the effect of reduce the impedance ground by effective external reference length analysis,the amount and distribution of external reference grounding bonding conductor as well the material and radius of external reference grounding bonding conductor when it has cited external reference grounding;research the compare about the rectangle and squareness grounding grid in reduce the impedance ground and electromotive force on-net and so on;research the compare about to improve the uniformity of impedance ground and earthing potential by copper grounding grid and steel grounding grid.In this paper , field measuring combined with numerical analysis,and the evaluation of current state combined with the evaluation of long-run development. After validate the creditability of numerical method about CDEGS by compared to field measuring data, combined with the analysis of safety limit about grounding grid , summarize the running state of Luodong Substation's grounding grid(integrity of grounding grid, split-flow of neutral point, touch voltage, step voltage, earth potential rise and so on),and through the analysis of each item measuring data, diagnoses the running state and the corrosion of the earthing installations, evaluaten the safety performance of Luodong Substation's grounding grid in power frequency short and lightning surge.