用于复合绝缘子伞裙老化无损检测的单边核磁共振方法

发布时间：2018-04-09 11:49

本文选题：复合绝缘子　切入点：老化　出处：《中国电机工程学报》2014年36期

【摘要】：硅橡胶复合绝缘子在中国电力系统中的用量逐年增加。对复合绝缘子老化状态的评估和监测关系到电力系统的安全运行。提出了一种单边核磁共振测量方法,实现对复合绝缘子伞裙老化状态的无损检测。研究主要包括核磁共振传感器设计及其信号分析两部分。使用有限元算法设计出一种半椭圆环状的单边核磁共振磁体,在磁体外部10 mm×10 mm×4 mm的测量区域内,建立了3.9 T/m的近似恒定梯度磁场。使用该静态梯度场,实现了伞裙材料的分层老化检测。该研究以3种不同运行时间的绝缘子为测试样品,使用CPMG序列激励样品,并对核磁共振回波信号峰值包络线进行一维横向弛豫时间的反拉普拉斯变换,从反演谱中提取出等效横向弛豫时间T2eff,实验表明:随着复合绝缘子老化程度加剧,T2eff减小;对于同一复合绝缘子,其T2eff由里及表,逐渐减小。所提出的等效横向弛豫时间T2eff能够表征复合绝缘子伞裙的老化程度,为评价其老化提供了一种无损检测的新方法。
[Abstract]:The use of silicone rubber composite insulators in Chinese power system is increasing year by year.The evaluation and monitoring of aging state of composite insulator is related to the safe operation of power system.A unilateral nuclear magnetic resonance (NMR) measurement method is proposed to detect the aging state of composite insulator umbrella skirt.The research mainly includes two parts: nuclear magnetic resonance sensor design and signal analysis.A semi-elliptical annular unilateral magnetic resonance magnet is designed by using finite element method. An approximate constant gradient magnetic field of 3.9 T / m is established in the measurement region of 10 mm 脳 10 mm 脳 4 mm outside the magnet.The static gradient field is used to detect the delamination aging of umbrella skirt material.In this study, three kinds of insulators with different running time were used as test samples, the samples were excited by CPMG sequence, and the peak envelope of nuclear magnetic resonance echo signal was transformed by anti-Laplace transform of one-dimensional transverse relaxation time.The equivalent transverse relaxation time T _ 2effe is extracted from the inversion spectrum. The experimental results show that the T2eff of the same composite insulator decreases gradually with the aging of the composite insulator increasing, and the T2eff of the same composite insulator decreases gradually from the inside and the surface of the composite insulator.The proposed equivalent transverse relaxation time (T2eff) can characterize the aging degree of the composite insulator umbrella skirt and provide a new nondestructive testing method for evaluating the ageing of the composite insulator umbrella skirt.
【作者单位】：输配电装备及系统安全与新技术国家重点实验室(重庆大学);
【基金】：国家自然科学基金项目(51107150;51377182)~~
【分类号】：TM216

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