油浸式电力变压器在超过铭牌额定值运行时,绕组导体发热量增加,绝缘纸由于温度上升而发生热老化,缩短其使用寿命.传统试验采用加速热老化研究油纸绝缘材料的热老化速率以获得热寿命模型.变压器实际运行中,由于绕组结构及绝缘油的流动散热作用,绕组绝缘纸层间温度场并不均匀,且绝缘油温度也低于绕组热点温度.采用传统的整体加热方式,将会由于绝缘油在高温下性能的快速劣化而使试验结果严重偏离实际情况.该文提出了一种新的绕组油纸绝缘热老化试验方法,采用电流发生器产生电流使绕组发热,将安放于绕组上的温度传感器信号反馈至电流发生器的调压装置,以控制输出电流的大小,从而获得试验所需的恒定老化温度.基于该试验平台开展了绕组油纸绝缘加速热老化试验,测试了老化过程中绝缘纸的聚合度变化规律.结果表明,与传统的加速热老化方法相比,该文提出的加速热老化试验方法不但更贴近变压器运行的实际情况,而且可以在同一个容器中,同时实现多个温度下的加速热老化试验,大大节省了老化所需的时间及成本.%Due to the temperature rise,the lifetime of insulation paper wrapped on the copper will be shortened.The accelerated thermal aging method is often adopted to do research on the thermal aging rate of oil-paper insulation materials under different temperature working points,to acquire the thermal lifetime model.According to existing aging test,both insulation paper and mineral oil were aged at the same temperature.In application,however,the temperature of mineral oil is lower than that of the hot spot due to oil circulation in transformer tank,and temperature gradients exist between oil and insulation paper.Serious deviation of the test results from the reality may appear for the fast degradation of the insulation oil's performance under high temperature condition.A new method is proposed in this paper for oil-paper insulation thermal aging test for windings.Current generator is adopted,a temperature sensor is fixed on the windings to get the temperature signal,and this signal is transmitted back to the voltage-controlling device.In this way,a relatively stable aging temperature is obtained.Based on this new method,oil-paper insulation accelerated thermal aging tests were finished,the variation rules of polymerization for the insulation paper in the aging process is analyzed.Test results with the proposed method in this paper is more tallies with the actual condition comparing to the traditional results.In addition,the accelerated thermal aging tests under different temperature points can be completed at the same time in only one tank,cost and time can also be substantially cut down.
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