110kV Substation Grounding Grid Design Method And Application

With the rapid development of economy,the scale of power system is getting bigger and bigger.When the system breaks down,the ground current is increasing.In the substation design,often because of the grounding system design backward or grounding resistance does not meet the requirements and make the power system stability and security greatly reduced,how reasonable and effective design of grounding resistance is the power system at this stage an urgent problem to be solved.This paper introduces the general requirements of the design of grounding grid,including the selection of horizontal and vertical grounding area and the depth of buried ground.Then,the methods of reducing resistance are analyzed,including electrolytic ion grounding electrode,deep well blasting and pressure reducing agent technology,long vertical grounding pole and grounding well.The vertical pole grounding,the influence of vertical grounding pole,the characteristics of vertical grounding pole and the application of vertical pole grounding in grounding grid are mainly studied.At last,the choice of vertical and deep well drag reduction materials is introduced.Subsequent design of substation grounding system Provides a methodological and theoretical basis.Focuses on the numerical calculation of ground potential parameters.First of all,the potential parameters of the grounding grid are introduced,including the allowable current standard of the human body,the step voltage,the allowable voltage,the transfer potential and so on.Secondly,the factors influencing the parameters of grounding grid are analyzed,including the influence of soil resistivity,step voltage,moisture,temperature,conductor size,grounding grid potential and other influencing factors.Thirdly,the calculation method of potential parameter of irregular grounding grid is introduced.The principle of constant current field theory and surface charge method is introduced briefly.At the same time,the general formula of irregular grounding grid resistance is introduced.Finally,an example analysis and comparison verification of the irregular grounding grid are given.The results of the method are compared with the moments method and the boundary element method to calculate the resistance results of the different grounding grids,and also the short vertical earth electrode with the long and short earth electrode compound Grounding network calculation results.Based on the design of grounding resistance system of 110kV substation,three methods are presented to improve the resistance of grounding resistance,including changing soil resistivity to reduce resistance.In this paper,local soil substitution method is used to complete the design of drag reduction.Grounding network to reduce the resistance of the lateral floor area,the main use of natural grounding method;the third method is to increase the vertical length of the grounding network to reduce the resistance,the main long vertical grounding method.Secondly,the design steps of the grounding system are introduced.The steps of designing the grounding grid are mainly based on the IEEE 80-2000 standard.The design flow diagram of the grounding network of the substation is given.The parameter calculation of 110kV substation grounding grid is given,including step voltage and contact voltage.The layout of grounding grid is designed according to the design of grounding network security model.The engineering background and the layout plan of ground network of 110KV substation are given.At last,the design diagram and the minimum cross-sectional area are calculated.The results show that the design grounding grid Meet the design requirements.