摘要
环氧固封式高频变压器采用环氧材料实现设备整体绝缘,可大幅降低设备体积,有效提高功率密度。大容量高频变压器内部温度分布不均,环氧树脂热应力分布集中致使整机开裂,导致绝缘失效。文中以10 kV高压大容量环氧固封式高频变压器为研究对象,建立了温度仿真模型和应力计算模型;获得了在额定运行工况下高频变压器热应力分布,其热应力主要集中在铁芯和绕组之间的环氧层;提出了降低局部热应力方法:通过材料改性提升环氧树脂导热系数降低高频变压器热点温度,可降低铁芯和绕组之间环氧树脂应力,安全系数由0.965提高至1.035;通过添加玻璃纤维增强材料和应力缓冲层双重措施,可大幅度降低应力集中区域材料弹性模量,降低内部最大应力,安全系数由1.035提高至2.691。研制了10 kV/200 kVA样机,通过–30~120℃高低温冲击试验,验证了其抗开裂性能和降低热应力方法的有效性。
The high-frequency transformer(HFT),sealed with epoxy material for overall insulation,effectively reduces equipment volume and improves power density.However,uneven temperature distribution within the large-capacity HFT can lead to concentrated thermal stress in the epoxy resin,resulting in machine cracking and insulation failure.This study focuses on a 10 kV high-voltage large-capacity epoxy-sealed HFT as the research subject.A temperature simulation mod-el and stress calculation model have been developed to determine the thermal stress distribution of the HFT under rated operating conditions.The thermal stress is primarily concentrated in the epoxy layer between the iron core and winding.A method for reducing local thermal stress is proposed by enhancing the thermal conductivity of epoxy resin through mate-rial modification in order to decrease the hot spot temperature of the HFT,and the stress in epoxy resin between iron core and winding can be reduced,thereby increasing safety factor from 0.965 to 1.035.Two measures are taken,such as in-creasing the glass fiber reinforced materials and stress buffer layer,thus,the modulus of elasticity of the encapsulated structure is greatly reduced,the maximum tensile force inside is lowered,and the safety coefficient is increased from 1.035 to 2.691,which guides the structural design of large-capacity epoxy encapsulated high-frequency transformers.A 10 kV/200 kVA prototype is developed to perform validation through−30~120℃high and low temperature impact tests,and its crack resistance performance and effectiveness of reducing thermal stresses methods are verified.
作者
李卫国
陈镔浩
赵国亮
乔光尧
靳艳娇
徐云飞
LI Weiguo;CHEN Binhao;ZHAO Guoliang;QIAO Guangyao;JIN Yanjiao;XU Yunfei(State Key Laboratory of Advanced Power Transmission Technology(State Grid Smart Gird Research Institute Co.,Ltd.),Beijing 102209,China)
出处
《高电压技术》
EI
CAS
CSCD
北大核心
2024年第9期3978-3987,共10页
High Voltage Engineering
基金
国家重点研发计划(2022YFB2404104)。
关键词
高频变压器
环氧树脂
应力分布
弹性模量
高低温冲击
high-frequency transformer
epoxy resin
stress distribution
elastic modulus
high and low temperature im-pact
