Optimization Design Of Grounding Grid Of 220kV Substation In High Soil Resistivity Area

In the substation electrical design,the grounding grid design,as a part of the lightning protection grounding design,plays an important role in the normal operation of the substation.On the one hand,the grounding grid can quickly evacuate lightning current and grounding fault current,and protect the safety of operators and equipment.On the other hand,when a lightning strike or short-circuit fault occurs,a reasonable grounding grid can weaken the harm of transient voltage or current to personnel or equipment,thus ensuring the normal production and operation of the substation.Therefore,in the electrical design of substation,the grounding grid design is a very important part.In this paper,taking Meizhou 220 kV Weishao Substation as an example,aiming at the problem of high soil resistivity,the grounding grid is optimized to achieve effective resistance reduction.The specific work is as follows:(1)Combined with the engineering survey of 220 kV Weishao Station and the investigation results of natural environment of 220 kV Weishao Station,the design direction of grounding grid is determined.(2)The CDEGS software is used to analyze the influencing factors of the external extended grounding grid and the grounding inclined shaft.The laying form,specification,laying position,grid density of the external extended grounding grid and the laying position,length and laying environment of the grounding inclined shaft are studied,and the results obtained are used to guide the design of the external extended grounding grid and the grounding inclined shaft,The relevant data can also be used to calculate the contact potential difference and step potential difference of the overall grounding grid in the later stage and optimize the design process of the grounding grid.(3)The grounding grid of 220 kV Weishao station is designed,and two resistance reduction schemes are proposed in combination with the site environment,namely,the resistance reduction scheme based on the extension grounding grid and the resistance reduction scheme based on the grounding inclined shaft.After analyzing its economy,it is finally determined that the resistance reduction scheme is based on the grounding inclined shaft and supplemented by the extension grounding grid,and the corresponding grounding impedance is calculated and the contact potential difference and step potential difference are verified.(4)Based on the actual situation of the grounding grid of Meizhou 220 kV Weishao substation,the risk control items for the construction and test of the substation grounding grid design are determined to ensure the quality of the grounding grid and the accuracy of the measurement data.Through the optimization design of the grounding grid of 220 kV Weishao station,the study on the influence factors of the resistance reduction measures of the extended grounding grid and the grounding inclined shaft,and the economic analysis of the resistance reduction measures,it can provide a reference for the engineering design of other high soil resistivity areas.