Research On Lightning Protection And Grounding Characteristics And Optimization Measures Of Photovoltaic Power Station

The proposal of the strategy of "carbon peak and carbon neutrality" brings great opportunities for the further development of photovoltaic power generation.Due to the influence of light and site,a large number of photovoltaic power stations operate in mountainous and desert areas with harsh environment.Photovoltaic power stations are vulnerable to thunderstorms because of the open terrain and lack of shelter.Therefore,the design and optimization of grounding device of photovoltaic power station plays an important role in ensuring the safety of personnel and the stable operation of photovoltaic power station.The lightning protection and grounding characteristics of photovoltaic power station and related optimization measures are studied in this paper.The main conclusions are as follows:(1)Whether it is photovoltaic array type or agro-optical complementary photovoltaic power station,considering the objective conditions that there are naturally multiple photovoltaic power generation equipment areas(photovoltaic arrays or photovoltaic greenhouses)surrounding the booster station of photovoltaic power station grounding network,it is proposed to use the grounding network in the power generation equipment area as the external grounding network to connect with the main grounding network in the booster station of photovoltaic power station.It provides a new measure for resistance reduction and potential optimization of photovoltaic power station.(2)Considering the length of connecting lines,number of connecting lines,area of grounding network,density,material of grounding body,soil structure,and direction of grounding body,CDEGS simulation was used to explore the resistance reduction effect of cross-connected grounding network on the main grounding network of photovoltaic power station.The main grounding network and the external grounding network of the photovoltaic power station are connected through connecting cables,which can reduce the grounding resistance of the main grounding network in most cases.The higher the soil resistivity,the higher the resistance reduction efficiency provided by the interconnecting ground network.At the same time,the simulation results can guide the practical application.In the actual engineering,the selection of the external grounding network should be as close to the main grounding network as possible,and the balance between the improvement and reduction of drag reduction efficiency caused by the increase of the number of connecting lines and the decrease of the spacing should be fully considered,so as to select the best connection line scheme.(3)Considering the length of connecting lines,number of connecting lines,area of grounding network,density of grounding network and number of grounding bodies,CDEGS simulation was used to explore the potential optimization effect of cross-connected grounding network on the main grounding network of photovoltaic power station.The photovoltaic power station main grounding network and external grounding network are interconnected through connecting lines,which can reduce the maximum contact voltage and step voltage of the main grounding network and optimize the potential distribution.The higher the soil resistivity,the higher the depressurization efficiency provided by the interconnected ground network.It shows that the optimization of contact voltage and step voltage of the interconnected ground network is more instructive for the location of photovoltaic substations with high soil resistivity such as desert beach.In actual engineering applications,at least two cables should be used to connect the external grounding network to the boundary point of the main grounding network.(4)The optimal design of the ground grid for the Hechan Jingneng agro-optical complementary photovoltaic power station and Zhangchang Shengyang photovoltaic array photovoltaic power station in Tai ’an area is carried out by using the method of mutual connecting ground grid.According to the distribution of the generating equipment area of the on-site photovoltaic power station,as well as the resistance reduction and potential optimization requirements of the main grounding network,the interconnection mode of the grounding network is determined.The final verification results show that the interconnecting ground grid can effectively reduce the ground resistance and optimize the potential distribution in both the agricultural and optical complementary photovoltaic power stations and photovoltaic array photovoltaic power stations,and the drag reduction efficiency and voltage reduction efficiency are both above 10%.The optimization measures of photovoltaic power stations’ interconnecting ground network and relevant simulation conclusions can provide reference for the design of photovoltaic power stations’ grounding network in practical engineering.