换流变压器套管的电气绝缘结构研究与设计优化

Study on Electrical Insulation Structure of Converter Transformer Bushing and Design Optimization

开展特殊运行工况下环氧浸纸复合绝缘材料的理化特性试验,大长径比、多极板电容芯子的主绝缘结构优化设计。研究了大电流、高电压、多谐波条件下套管金属载流结构涡流发热和绝缘介质焦耳发热规律以及电热耦合条件下套管芯子径向稳态、暂态的电场、温度分布规律,并对温变、场变非线性条件下套管尾部绝缘配合结构—出线装置结构进行型式优化设计。结果表明:干式换流变压器套管内部极板的厚度一般设计为0.5~3.0 mm,且套管芯子内部的径向场强呈“U”型分布,其场强最大值为8.75 kV/mm,轴向电场强度分布均匀,下轴向场强约为0.5 kV/mm。

The physical and chemical properties tests of epoxy impregnated paper composite were conducted under special operating conditions.The main insulation structure with large aspect ratio and multi-polar plate capacitor core was optimized.The rules of eddy current heating of bushing metal current-carrying structure and Joule heating of insulating medium under high current,high voltage,and multi-harmonic conditions were studied.The electric field and temperature distribution laws of bushing core at radial steady state and transient were studied under electro-thermal coupling conditions.The structure type of insulation matching structure at bushing tail—outlet device was optimized under non-linear conditions of temperature and field variation.The results show that the thickness of inner plate of dry-type converter transformer bushing is designed to 0.5-3.0 mm generally.The radial field strength inside the bushing core is U-shaped,its maximum field strength is 8.75 kV/mm,the axial electric field strength is distributed evenly,and the upper axial field strength is about 0.5 kV/mm.