±800kV换流变压器套管电场分布三维仿真研究

The 3D Simulation of Electric Field Distribution for ±800kV Converter Transformer Bushing

为解决特高压直流套管绝缘破坏问题,分析了±800kV特高压直流套管的特性,利用Ansoft软件建立套管的三维仿真模型,计算了特高压直流套管在稳态直流、工频交流和极性反转电压下套管内部的精确场强和电位分布,并得到了在温度梯度作用下直流电压和极性反转电压下的特高压套管的电场、电位仿真结果。结果表明,直流电压下,套管的最大电位与交流电压相比,高出约37%。在法兰处,直流电压下其最大电场强度为2.07MV/m,交流电压下其最大电场强度为1.5MV/m,最大电场强度高出27.5%。靠近中心导管端部分的SF6气体中电位分布较集中。温度梯度影响下套管的硅橡胶伞裙最高场强出现在极性反转完成时第5片伞裙附近,最高场强达到1.16 MV/m。相比于常温下硅橡胶伞裙最高场强0.85 MV/m提高了36.4%,说明套管的电场强度更容易发生畸变,将导致绝缘问题的发生。研究成果可为特高压直流套管设计提供参考。

In order to solve the problem of insulation damage of UHV DC bushing, the characteristics of ±800 kV UHV DC bushing were analyzed. The three-dimensional simulation model of bushing was established by Ansoft software. The field strength and potential distribution of UHV DC bushing were calculated under steady state DC, power frequency AC, and the polarity reversal voltage. At the same time, the DC voltage under the temperature gradient and the electric field and potential simulation of the UHV bushing under the polarity reversal voltage were obtained. The results show that the maximum potential of the bushing is about 37% higher than the AC voltage at DC voltage. At the flange, the maximum electric field strength at DC voltage is 2.07 MV/m, the maximum electric field strength under AC voltage is 1.5 MV / m, and the maximum electric field strength is higher than 27.5%. The potential distribution in the SF6 gas near the end of the central conduit is concentrated. The highest field strength of the silicone rubber shed of the casing under the influence of temperature gradient appeared near the fifth awning at the completion of the nolarity reverse, and the highest field strength reached 1.16 MV/m. Compared with the highest field strength of silicone rubber shed at normal temperature, the maximum field strength of 0.85 MV/m is increased by 36.4 %, indicating that the electric field strength of the bushing is more prone to distortion, which will lead to insulation problems. The research results can provide reference for the design of UHV DC bushings.