500kV并行线路工频电场测量及影响因素分析

为了使人们了解并行超高压线路工频电场的分布特性,积极配合大电网建设,采用EFA-300电磁分析仪对并行500kV线路某段工频电场进行了实地测量,证实并行线路下方工频电场值满足国标要求,利用逐次镜像法建立了高压架空输电线路的工频电场仿真模型,通过与实测值对比,分析验证了该模型的准确性,进而基于此模型分析了不同相序、对地高度、接近距离、相间距离和初相位差对并行输电线路地面上方1.5m处电场分布的影响。结果表明,合适的相序、初相位差和抬升杆塔高度可以减小线路下方的工频电场;减小两回路中心接近距离,可明显节省输电走廊。

Measurements and Influencing Factors Analysis of Power Frequency Electric Field under 500 kV Parallel Transmission Lines

In order to make people understand the distribution characteristics of power frequency electric field for extra-high voltage (EHV) parallel lines and actively cooperate with construction of power grid, the electric field of two 500 kV parallel transmission lines was measured with EFA-300 electromagnetic analyzer, which demonstrates that the electric field under parallel lines satisfies the requirements of national standard. A simulated model was established by successive image method to calculate the power frequency electric field of HV overhead lines. The accuracy of the theoretical model is verified though comparing with measurements. On the basis, influences on the electric field distribution at 1.5 m above the ground were analyzed including phase sequence, clearance of conductor to the ground, approaching distance, phase spacing and the initial phase difference when the two transmission lines are in parallel. The results show that appropriate phase sequence, appropriate initial phase difference and increase of height of tower can inhibit the electric field while the decrease of approaching distance between two lines can save the transmission corridor effectively.