Research On Tower Grounding Resistance Reduction Measures In Complex Terrain Of Mountain Area

Transmission line towers in mountain areas are erected on the hilltop orhillside，grounding devices are confined by space at many times, and taking intoaccount the high rate of soil resistivity and complex terrain, it is common thattower grounding resistances are beyond the requirements.In order to reducegrounding resistances of the towers whose grounding resistances are failure, wemust have a detailed understanding of these towers soil’s structure and soilresistivity, so these credible data can support for the following study.This paper proposes an recursive algorithm to calculate current fieldgenerated by point current source in horizontal layered soil. Combining withProny method and Lipsitzch integration, we can obtain potential value in layers ofsoil generated by point current. By the least squares method, the objectivefunction of soil apparent resistivityρmmeasured at multiple pole spacing andρccalculated can be set up.Then, by variable substitution, change constrained optimization problems intounconstrained optimization problems, determine the initial parameters, we canobtain horizontal layered soil’s equivalent layers、thickness、and soil resistivity ofspecific layers by unconstrained optimization methods. The results are similar tothe results derived from RESAP of CDEGS.For the towers whose basis are not built, this paper propose to adopt the SYJnew grounding device to reduce grounding resistance, this device have advantagessuch as small taken space, superior diffuse function, easy construction. The resultscalculated by deduced theoretical formula are very similar to the results obtainedby MATLAB. For the towers whose basis are built, this paper propose to add“thelimb-like”horizontal grounding polarity, respectively propose design plan of thethree types towers whose grounding resistivity are excessive, so we can discoversome law:towers whose grounding resistance are slightly exceeded often characterized by simple layered soil(mainly two layers),low soil resistivity, so thelength of horizontal grounding polarity is not large. Towers whose groundingresistance are normally exceeded often characterized by two layers or three layerssoil, high soil resistivity, the length of horizontal grounding polarity mainly aremore than 120m,GPF-94 reducing-resistance materials can be appropriatedconsidered. Towers whose grounding resistance are highly exceeded oftencharacterized by complex layered soil, high soil resistivity, large section sizereducing-resistance materials must be adopt to get desired effect. These laws canprovide reference in grounding resistance reduction program.