基于PDC法的大型发电机定子线棒主绝缘热老化状态评估  

Thermal ageing state evaluation of main insulation of large generator stator bar based on PDC method

作　　者：王思宇 周凯[1] 朱光亚 杨帅 刘雁 WANG Siyu;ZHOU Kai;ZHU Guangya;YANG Shuai;LIU Yan(College of Electrical Engineering,Sichuan University,Chengdu 610065,China;Dongfang Electric Machinery Co.,Ltd.,Deyang 618000,China)

机构地区：[1]四川大学电气工程学院,四川成都610065 [2]东方电气集团东方电机有限公司,四川德阳618000

出　　处：《绝缘材料》2024年第6期68-75,共8页Insulating Materials

基　　金：国家自然科学基金资助项目(52107160;51877142)

摘　　要：大型发电机在运行过程中会受到热应力等因素的影响,造成定子线棒绝缘劣化乃至失效,影响发电机的安全稳定运行。为了明确极化-去极化电流(PDC)法对于定子线棒主绝缘性能评估的有效性,首先采用PDC法评估热老化状态的定子线棒主绝缘性能。依据PDC测试结果,提取出稳态电导电流、0.1 Hz极化/去极化损耗、不对称系数等基本特征参量;随后再利用奇异值分解(SVD)算法对线棒样本的PDC数据进行扩展德拜模型的分析,得出其模拟电路的支路数和支路参量,通过分析明确老化过程中上述特征参量的变化规律。最后对不同热老化时长的样本进行傅里叶变换红外光谱(FTIR)分析,从微观角度进一步明确上述绝缘后固化和劣化过程的机理。结果表明:随着绝缘老化程度加剧,稳态电导电流和0.1 Hz极化/去极化损耗增加,不对称系数偏离1的程度加剧,界面极化时间常数τ2减小。Large generators are affected by factors such as thermal stress during operation,resulting in deterioration or even failure of stator bar insulation,which affects the safe and stable operation of the generator.In order to clarify the effectiveness of the polarization and depolarization current(PDC)method for evaluating the main insulation performance of stator bars,at first,PDC method was used to evaluate the main insulation performance of stator bars in the thermal ageing state.According to the PDC test results,the basic characteristic parameters such as the steady-state conductance current,0.1 Hz polarization/depolarization loss,and asymmetry coefficient were extracted.Then,singular value decomposition(SVD)algorithm was used to analyze the PDC data of the bar sample with the extended Debye model,and the branch number and branch parameters of its analog circuit were obtained.Through analysis,the change regulation of the above characteristic parameters during ageing was clarified.Finally,Fourier transform infrared spectrum(FTIR)analysis was conducted on samples with different thermal ageing durations to further clarify the mechanism of post-insulation curing and degradation from a microscopic perspective.The results show that as the degree of insulation ageing intensified,the steady-state conductivity current and 0.1 Hz polarization/depolarization loss increases,the degree of asymmetry coefficient deviation from 1 intensifies,and the interface polarization time constantτ2 decreases.

关 键 词：定子线棒绝缘 极化/去极化电流法 热老化 特征参量 

分 类 号：TM303.4[电气工程—电机]