Study On The Grounding System Of The Sanhekou, Hydro Junction

The grounding system of the substation is an important part of the power station.It is a key link in maintaining the safe and reliable operation of the power system and ensuring the safety of the station and the equipment."Yin Han Ji Wei" is the "South-North Water Diversion" project of Shaanxi Province,it is also the largest inter-basin water transfer project in Shaanxi Province.It is of great significance to alleviate the contradiction between supply and demand of water resources in Guanzhong area of Shaanxi Province,improve the regional ecological environment and ensure the sustainable development of regional economy and society.This paper studies the grounding problem of "Yin Han Ji Wei"Sanhekou Water Conservancy Project,analyzes the imprinting factors of grounding impedance and its influence respectively,calculates the maximum short-circuit current into the ground,and calculates and verifies the ground potential distribution in turn it is of great practical significance to make reasonable suggestions on the grounding system of "Yin Han Ji Wei" Sanhekou Hydropower Station.The main content of this paper is as follows:(1)Grounding grid numerical calculation method.First of all,based on the node voltage method,introduced the grounding grid parameters of the principle.On this basis,the method of solving the Green’s function in the horizontal multi-layer soil is deduced and discussed.Finally,the CDEGS software package is mainly used in the numerical calculation of this paper.(2)Establishment of numerical model for the control of the "Yin Han Ji Wei" Sanhekou Water Conservancy Project.Firstly,based on the results of the measured geodetic resistivity of Wenner method,the horizontal stratified soil model of the "Yin Han Ji Wei" Sanhekou Sanhekou hydroproject is obtained by the inversion calculation.At the same time,the corresponding conductor is established according to the actual model of the "Yin Han Ji Wei" Sanhekou hydroproject model.Combined with the horizontal stratified soil model and the established conductor model,the equivalent geodetic resistivity of the "Yin Han Ji Wei"Sanhekou Water hydroproject is calculated.(3)Calculation and Analysis of Grounding Impedance of "Yin Han Ji Wei" Sanhekou Water Conservancy Project.The variation degree of grounding impedance is calculated when the soil resistivity,ground material,dam depth,water resistivity and short-circuit point position are calculated,and the resistance reduction measures of "Yin Han Ji Wei" Sanhekou Water hydroproject were discussed.(4)Calculation of short-circuit current of "Yin Han Ji Wei" Sanhekou Water Conservancy Project.Based on ATP-EMTP,the short-circuit current calculation model of"Yin Han Ji Wei" Sanhekou Water hydroproject is established,and the short-circuit current in different places is calculated and analyzed.The results show that the steady-state effective value of the short-circuit current is 2.346kA in the most serious case,and the attenuation coefficient of the DC component is 1.5445,then the short-circuit current is 3.623kA after considering the transient effect.(5)Calculation of potential distribution of "Yin Han Ji Wei" Sanhekou Water Conservancy Project.The ground impedance is only a representation of the grounding effect of the ground grid.The touch voltage,step voltage and the potential difference between the network is a direct impact on personal and equipment safety parameters.In this paper,the potential distribution of the "Yin Han Ji Wei" Sanhekou Water Conservancy Project is calculated and compared with the personal and equipment safety threshold,and the safety performance of the ground network is verified and the corresponding isolation and protection measures are put forward.