基于体表电场的500 kV交直流同塔双回线路进入等电位的路径研究

Research on Entering Path to Equipotential Level of 500 kV AC⁃DC Double⁃circuit Transmission Line According to Body Surface Electric Field Strength

500 kV交直流同塔混压线路塔头间隙紧凑且导线布置复杂,对进入等电位的方式和路径提出了严格的要求。为确定作业人员进入500 kV交直流同塔混压双回线路等电位的体表最大电场的特性和路径,针对张北500 kV柔性直流输电线工程的交直流同塔混压双回输电线路典型的直线塔,在Ansys有限元仿真软件中构建模型,分析了同塔混压双回线路交流线路中相、边相和直流线路典型作业工况下,等电位人员进入等电位的所有可能路径上体表电场值的分布规律;基于体表最大电场的分布规律确定了进入等电位的最优路径。结果表明:在交直流同塔双回线路中交流回路塔窗内中相和边相导线处的体表电场最大值分别为1875 kV/m和1032 kV/m,在直流极导线处体表电场最大值为1110 kV/m;人员垂直进入等电位时整个过程的平均体表电场最大。对于交直流同塔混压双回线路,进入路径的角度对人体体表电场具有重要影响,进入交流酒杯塔的中相和边相等电位时的最优角度分别为45°和50°,而进入直流极导线路径的角度则为30°最佳。

The clearance of the 500 kV AC⁃DC mixed voltage lines on the same tower is narrow and the arrangement of the wires is complicated.In order to determine the maximum electric field strength on body surface and the enter⁃ing path to equipotential level for the workers,who are engaged for live operation on 500 kV AC⁃DC mixed⁃voltage double⁃circuit transmission line,the straight⁃line tower for the AC⁃DC mixed⁃voltage double⁃circuit transmission line of the Zhang⁃Bei flexible 500 kV DC transmission line project is taken as an example to establish model in the fi⁃nite element simulation software Ansys.The body surface electric field strengths of a worker entering into all possible equipotential paths of the AC circuit of the mixed⁃voltage double⁃circuit line are calculated and analyzed in the typi⁃cal working conditions of middle phase,side phase,and DC circuit,and then the optimum path for entering equipo⁃tential level is determined according to the maximum electric field strength distribution on body surface.The results show that the maximum values of the body surface electric field strength at the middle⁃phase and side⁃phase wires in the AC circuit tower window are 1875 and 1032 kV/m,respectively,and the maximum value at the DC pole wires is 1110 kV/m.The average body surface electric field strength is the largest during the whole process of the worker en⁃tering the equipotential level vertically.For the AC⁃DC mixed⁃voltage double⁃circuit line on the same tower,the en⁃tering angle has an important influence on the electric field distribution on human body surface.The optimal angles entering the equipotential level of middle phase and side phase of the wires in the AC cup type tower are 45°and 50°,respectively,while the optimal angle entering the equipotential path of the DC pole wires is 30°.