Research On The Way Of Entering The Electric Field And Optimal Potential Transfer Distance For Live Working On ±800kV Transmission Line

With the rapid development of China’s economy,the demand for electricity is also increasing day by day.The transmission capacity and scale of the transmission network can no longer meet the needs of social and economic development.Therefore,in recent years,China has successively built the UHV DC transmission demonstration project with the advantages of large transmission capacity and long transmission distance.However,the construction technology of ±800kV transmission line is relatively high and the completion time is still short,which puts higher requirements on the safety of live working on the line.Because the process of potential transfer is the highest risk and the most important part in live working,if the safety protection is not perfect,it is very likely threaten the life safety of the worker and the stable operation of the line.Therefore,we should comprehensively evaluate the way of entering the electric field of the worker,in-depth study on the process of potential transfer during the live working of the UHV DC transmission line,and obtain the best transfer distance for the live workers.It is of great significance for the safe operation and maintenance of ±800kV transmission line.The paper first studies two different ways of entering electric field by using the hanging basket method and soft ladder method.Taking the demonstration project of ±800kV Fu-long to Feng-xian transmission line as an example,the typical small angle tower transmission line is chosen as the research object,and the equal proportion model is built by using the Inventor drawing software.The reliability and safety of these two ways of entering electric field are verified by the safe distance,combined gap and live working risk rate between ground potential,intermediate potential and equipotential;Then using Ansoft simulation software to calculate the surface electric field strength of the worker on entering electric field path.Secondly,in order to determine the optimal potential transfer distance of the potential transfer during the live working of ±800kV transmission line.The paper then began a study of the whole process of potential transfer.For the influence of partial discharge current on the discharge process in the early stage of potential transfer,a hydrodynamic model is established.The developing speed of streamer and the current density change with time are calculated and analyzed.For the transient response process in the post stage of potential transfer,the transient response calculation model suitable for the post stage of potential transfer is established,and the variation characteristics of human body potential and transfer current are analyzed.Finally,according to the model that has been built,the variation of human body potential and discharge current under different transfer distances is studied,and the optimum potential transfer distance when the live working on ±800kV transmission line is determined.The results show that it is better for the workers to use the hanging basket method to entering and leaving the electric field;In the early stage of potential transfer,with the increase of discharge time,the speed of the streamer development increases and current density increases;In the post stage of transfer,the human potential and the transfer current decay with time,and the decay time is about 1μs;The recommended potential transfer distance is about 0.45m when the live working on ±800kV transmission line.The research results provides a certain theoretical reference value for the safety of workers and the smooth development of live working on transmission lines.