CAJ | 학술논문

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×10mm×4mm的测量区域内，建立了3.9T/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T2ef ，实验表明：随着复合绝缘子老化程度加剧，T2ef 减小；对于同一复合绝缘子，其T2ef 由里及表，逐渐减小。所提出的等效横向弛豫时间 T2ef 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。
규상효복합절연자재중국전력계통중적용량축년증가。대복합절연자노화상태적평고화감측관계도전력계통적안전운행。제출료일충단변핵자공진측량방법，실현대복합절연자산군노화상태적무손검측。연구주요포괄핵자공진전감기설계급기신호분석량부분。사용유한원산법설계출일충반타원배상적단변핵자공진자체，재자체외부10 mm×10mm×4mm적측량구역내，건립료3.9T/m적근사항정제도자장。사용해정태제도장，실현료산군재료적분층노화검측。해연구이3충불동운행시간적절연자위측시양품，사용CPMG 서렬격려양품，병대핵자공진회파신호봉치포락선진행일유횡향이예시간적반랍보랍사변환，종반연보중제취출등효횡향이예시간T2ef ，실험표명：수착복합절연자노화정도가극，T2ef 감소；대우동일복합절연자，기T2ef 유리급표，축점감소。소제출적등효횡향이예시간 T2ef 능구표정복합절연자산군적노화정도，위평개기노화제공료일충무손검측적신방법。
Silicone rubber insulator is widely used in the power system, the assessment and monitoring of its aging status are critical to the safe operation of the power system. This paper presented a non-destructive unilateral nuclear magnetic resonance(NMR) method to measure the aging status of silicon rubber insulator. The research included two parts: the design of the NMR sensor, and the analysis of the NMR signal. The magnet of the NMR sensor with a semi-elliptical structure was designed by finite element methods. A static magnetic field with constant gradient of 3.9T/m was built in the measurement area with a size of 10mm×10mm×4mm. With this gradient field, the detections of various depths into the insulator shed were realized. Three groups of insulators with different service times were measured, and the CPMG sequence was employed to excite the samples. By performing the Inverse Laplace transform to the peak-envelope curve of NMR echoes, the one dimensional distribution of transverse relaxation time was obtained. From the one dimensional distribution, the effective transverse relaxation timeT2ef was extracted. It demonstrates that:T2ef decreases as the service time of the insulator increases;T2ef decreases as the measurement moves from the middle part to the surface of the shed.T2ef can reflect the aging status of the silicone rubber insulator shed. The result can provide a new non-destructive detection method for assessing the aging level of the composite insulator.