【作者】 李增；

【导师】 吴广宁；

【作者基本信息】 西南交通大学 ， 高电压与绝缘技术， 2007， 硕士

【摘要】 变电站接地的主要目的是为了保障供电系统能够安全可靠地运行和保障人身及设备的安全。在我国接地规程及IEEE Std 80-1986中均只考虑了采用均匀土壤模型进行地网接地电阻的计算。但在工程实际中，大部分地区的土质比较复杂，按照均匀土壤考虑设计时会产生较大的设计误差。目前，多数研究者认为按照双层土壤对多层土壤中接地网的电气特性进行分析可以提高设计精度，但各种参数对接地网电气特性的影响尚不清楚，因此需要研究各种参数变化时复杂土壤结构中接地网电气特性的变化规律，找出水平多层土壤的等效简化分析方法，为接地网的设计提供理论指导。本文仿真分析了土壤电阻率、土壤厚度、反射系数等参数对水平双层土壤、垂直双层土壤和水平三层土壤中地网接地电阻的影响规律。针对接地网面积、土壤电阻率和反射系数等参数对等效均匀土壤电阻率的影响规律，找出了影响等效均匀土壤电阻率的重要参数，建立了水平双层土壤结构等效成单层土壤结构的求解模型。研究了复杂土壤结构中接地系统设计的方法和步骤，提出了青藏铁路格拉段接地网的设计原则。文中重点讨论了接地网材料的选择和接地电阻的测量方法。接地网材料选用铜还是钢要综合考虑经济及腐蚀等各种因素的影响，同时还要依据环境条件选择合适的防腐方法。在测量地网的接地电阻时，应了解接地系统附近土壤分层结构情况，综合考虑各方面影响因素，选择合理的电流极引线和电压极的布置位置及相应的测量方法，才能获得准确的测量结果。更多还原

【Abstract】 The substation grounding system is important to the reliable operation of power system and the safety guarantee of person and equipment. Only uniform soil model is considered to calculate the grounding resistance of the grounding grid in DL/T621-1997 and IEEE Std 80-1986. In practice, the soil structure is complex in many regions, a big error would occur if only the uniform soil model considered. At present, most researchers think that the multi-layer soil structure can be simplified as an equivalent two-layer soil structure to analyze the electrical character. But the influence of various parameters on the electrical character of the grounding grid is not clear, so the influence of different parameters on the electrical character of the grounding grid in the multilayer soil is studied. The simplification method for the multilayer soil structure is proposed. This method is helpful to the design of the grounding system in the multilayer soil.The influence of soil resistivity, soil thickness and the reflective coefficient on the grounding resistance of the grounding grid in various structures is analyzed. The influence of grounding area, soil resistivity and the reflective coefficient on the equivalent soil resistivity is also analyzed. The key parameters that influence the equivalent soil resistivity are found, and the system model of BP ANN to calculate the equivalent soil resistivity is discussed. The method of designing the grounding system in the complex soil structure is introduced, and the design principles of grounding grid in Ge-La segment are proposed. The selection of grounding grid material and the measurement of grounding resistance are discussed. To select copper or steel as the grounding grid material depends on outlay, corrosion and other factors, and the corrosion-proof measures need to be taken according to the environment. The soil structure around the substation should be studied before measuring the grounding resistance of the grounding grid, with the proper arrangement of current and voltage probes as well as proper measurement method, the accurate result can be obtained.更多还原