Optimization Design And Safety Assessment Of Substation Grounding Grid

In recent years, with the rapid development of economy, the power short circuit capacity increases, which increase the grounding fault current and make it difficult to reduce the grounding resistance. Due to the rise of the grounding fault current, the grounding grid of the constructed substation can hardly meet the actual demand, which results in more and more earth fault. The earth design to determine the reasonable grounding scheme and reduce the grounding resistance in the construction process is one of the key concerns in the substation construction.The thesis starts with the design principles of substation grounding system and in order to realize the safety evaluation index of grounding system, it researches varied methods of reducing the grounding resistance of the substation. It focuses on the grounding grid design of Wuchuan 220kV substation, and studies the impact of corrosion resistance of grounding materials on the service life of grounding grid. To choose between galvanized flat steel and flat copper as the grounding material of Wuchuan 220kV substation, it compares not only their conductivity, thermal stability and resistance to corrosion but also their annual costs in a life cycle before selecting the latter.Then, it analyzes the engineering geological condition of Wuchuan 220kV substation, and inverts the layered model of soil resistivity. Through the short-circuit current calculation, it determines the design goal of the substation grounding system.In the end, with the CDEGS software, the author assesses comprehensively indexes of three schemes including the grounding resistance, grounding potential rise, touch and step potential difference before determine the grounding grid design.