Calculation And Characteristic Of 3-D Total Electric Field Near HVDC Transmission Tower

With the rapid development of economy in China,the demand for power energy increases evidently.However,the economic development and the resource distribution of China are extremely unbalanced.It is a necessity to develop the large-capacity and long-distance DC transmission lines.The electromagnetic environment problem caused by transmission lines has become more and more prominent,so relative standards have been made by our country to limit the electric field strength.As an important framework of power transmission,power tower inevitably can affect the nearby electromagnetic environment,and the safety protection for live working is very necessary when transmission line is in operation.So in-depth study on electric field distribution around power tower is of great significance,and the study can provide reference for the engineering design.Firstly,according to the basic principle of charge simulation method(finite length line unit);the electric field around the power tower can be calculated by the Deutsch assumption.The experimental platform of the scale tower is built in the laboratory,then the platform is modeled and calculated by the above calculation method,the measurement results are in good agreement with the calculated values,which verifies the correctness of the calculation method.Secondly,in order to analyze the discharge differences,the surface electric field of the sub-conductor near the power tower is calculated by using the simulation charge location optimization algorithm.The influence of the tower on the surface electric field of the conductor is analyzed,and the factors affecting the calculated result of the electric field are discussed.Finally,the electric field under overhead transmission lines in a span with the consideration of conductor sag is calculated,and the difference between two-dimensional calculation and three-dimensional calculation is discussed.The results show that there is little difference between the two-dimensional calculation with minimum height and the three-dimensional calculation,but the two-dimensional calculation with average height is quite different compared with the above two models.Then a 3-D electric field calculation model around 1500kV self-supporting tower is built,the electric field distribution characteristic of the ground and its surface is calculated,and the influence distance of power tower on nearby electric field is analyzed,also the factors affecting the calculated results are discussed.Similarly,a 3-D electric field calculation model around±500kV angle Sirain tower is built,and the characteristic of the ground electric field distribution around angle tower is analyzed.In the end,a 3-D electric field mathematical calculation model around DC side outside±500kV converter station is built,the electric field distribution of the ground is calculated,and the influences of converter station and power tower on electric field are analyzed,also the factors of structural parameters on ground electric field are discussed.Through the calculation and analysis of the above three-dimensional structure,this paper can provide some reference and prediction for the engineering application.