高频脉冲下电-热应力对聚酰亚胺绝缘寿命的耦合作用分析

Coupling Effect of Electrical and Thermal Stresses on Insulation Life of Polyimide Under High Frequency Impulses

高频电力设备的绝缘老化行为受电压参数和环境温度等多个因素的共同影响。为了探究这些影响因素的主次顺序以及因素间的交互作用,基于正交实验设计理论,采用高频正弦电压和球-板电极结构,研究了聚酰亚胺绝缘寿命随电压频率(5~30 kHz)、幅值(1.5~3.0 kV)和环境温度(13~180℃)的变化情况。结合极差分析、方差分析和关系图法讨论了3个因素对绝缘寿命的影响程度及其交互作用的大小顺序,并分析了因素水平变化对电、热应力耐受系数以及多因素协同作用效果的影响。结果表明:频率和幅值对绝缘老化的加速作用接近,且远大于温度的影响;同时,频率和幅值的交互作用最大,其次为幅值和温度、频率和温度的交互作用;交互作用的存在使材料对某一因素的耐受系数随着其它因素水平的提高而降低,并且多因素共存时的协同作用要弱于各因素独立作用的叠加效果。该研究方法为分析多因素耦合作用下的绝缘老化行为提供了一种新思路。

The insulation aging behavior of high frequency electrical equipment can be affected by multiple factors.In order to figure out the influence degree of different factors and their interactions,insulation life of polyimide film was studied based on orthogonal experimental design.High frequency sinusoidal voltage and sphere-to-plane electrode were used,and the designed ranges of frequency,amplitude and ambient temperature were 5~30 kHz,1.5~3.0 k V,and 13~180℃,respectively.The influences of these three factors on lifetime and their interactions were discussed based on range analysis,variance analysis,and relation graph.Also,the effects of factor level variation on tolerance coefficients to electrical and thermal stresses were analyzed,as well as the influence on synergistic action of three factors.Results indicate that accelerated effects of frequency and amplitude on insulation aging are similar,which are much larger than that of temperature.Besides,the interaction between frequency and amplitude is the largest,followed by that between amplitude and temperature,and that between frequency and temperature.Interactions between three factors cause the decrease of endurance coefficient to a certain factor with the improvement of other factor levels,and consequent the mitigation of the joint effect of coexisting multi-factors.The method described here provides a new way to study aging behavior of insulation material under the coupling effect of multi-factors.