换流变压器套管出线装置许用场强及其绝缘结构型式设计研究

Study on Allowable Field Strength of Converter Transformer Bushing Outlet Device and Pattern Design of Its Insulation Structure

分析了换流变压器尾部出线装置在各种不同运行工况下的许用场强,建立典型出线结构有限元仿真计算模型,在极性反转等各种电压型式下讨论了出线装置瞬态电位、电场分布特征,结合许用场强得出关键路径的绝缘裕度。结果表明:运行温度、直型屏障数量、直型屏障位置对出线装置电场分布的影响显著。随着温度的升高,均压球包覆中的电场强度先逐渐降低后略微升高,直型屏障中的电场强度逐渐下降,重载高温条件下较易发生纸板闪络等绝缘事故。本文提出的出线装置许用场强及绝缘结构型式设计可为换流变压器出线结构的设计提供参考。

The allowable field strength of the outlet device at the tail of converter transformer under various operating conditions was analyzed.A finite element simulation calculation model of typical outlet structure was established,and the transient potential and electric field distribution characteristics of the outlet device were discussed under various voltage types such as polarity reversal.The insulation margin value of the critical path was obtained by combining the allowable field strength.The results show that the operating temperature,straight barriers number,and straight barriers position have significant effects on the electric field distribution of the outlet device.With the increase of temperature,the electric field strength in pressure equalizing ball with coating decreases at first and then increases slightly,and the electric field strength in straight barrier decreases gradually.Under heavy load and high temperature conditions,it is easy to occur insulation accidents such as pressboard flashover.The proposed allowable field strength and insulation structure pattern of outlet device can provide reference for the design of outlet structure for converter transformer.