变压器铁芯搭接区磁热等效及温升影响研究

Research on magnetic heat equivalent and temperature rise of the lap area of transformer core

针对变压器叠片铁芯接缝搭接区温升异常和损耗难以实测的问题,提出了搭接区等效损耗方法来实现对铁芯接缝处损耗突变的准确计算。首先建立铁芯接缝搭接区三维等效模型,通过梯度曲线确定搭接区等效范围,得出接缝区等效损耗(JBF)的计算公式,并研究了JBF的影响因素;然后建立考虑JBF的变压器整体温升模型,计算并分析开路试验下铁芯及结构件上的不同热点及特定曲线上的温升及影响因素;最后搭建了变压器铁芯温升试验平台实测接缝搭接区和夹件的热点温度,结果显示测量值和计算值的相对误差均小于2.50%,证明了计算方法的有效性。所提出的搭接区等效损耗计算方法为变压器铁芯损耗评估及工程设计提供了理论基础,对变压器安全运行和在线监测具有重要意义。

There are abnormal temperature rise and difficult measurement of loss in the lap joint area of transformer laminated core joint. To solve these problems, this study proposes the joint building factor(JBF) method to obtain the accurate calculation of loss mutation at the lap joint. Firstly, a three-dimensional equivalent model of the overlapped zone of core joint is formulated and the equivalent range of the overlapped zone is determined by the gradient curve. Meanwhile, the calculation formula of JBF is determined and the influencing factors of JBF are studied. Then, the whole temperature rise model of transformer considering JBF is established. The temperature rise and influence factors of different hot spots on iron core and structural parts under open circuit test are calculated and analyzed. Finally, the temperature rise test platform of transformer core is built to measure the temperature of joint lap area and hot spots of clamps. Experimental results show that the relative error between the measured value and the calculated value is less than 2.50%, which proves the effectiveness of the calculation method. Therefore, this method of equivalent loss in the lap area provides a theoretical basis for transformer core loss assessment and engineering design. It is of great significance for transformer safety operation and on-line monitoring.