基于模态分析的GIS盆式绝缘子裂纹缺陷检测方法研究

GIS盆式绝缘子的缺陷检测对于保障电力系统安全运行具有重要意义。振动法由于具有检测灵敏度高和无损检测等优点成为当前电力设备故障诊断研究的热点问题。为给振动法检测盆式绝缘子开裂提供理论指导,文章建立了正常或含有缺陷盆式绝缘子的三维模型,采用有限元法计算了盆式绝缘子在不同气室压力和不同裂纹大小时的模态频率。研究结果表明,当盆式绝缘子无裂纹时,绝缘子会出现重根模态,而当盆式绝缘子有裂纹时,绝缘子没有重根模态。当盆式绝缘子下表面压力较小时,与两侧气室压力相同时相比,模态频率呈下降趋势,而当盆式绝缘子上表面压力较小时,模态频率呈增加趋势。盆式绝缘子存在裂纹时,模态频率呈下降趋势,随着裂纹深度的增加,模态频率下降幅度也会增大。计算结果表明采用振动法检测盆式绝缘子机械状况具有可行性。

Research on Crack Defect Detection Method for GIS Basin-type Insulators Based on Modal Analysis

It is of importance to monitoring defects of GIS basin-type insulators for guaranteeing the security operation of power systems. The vibration method becomes a research hot topic in fault diagnosis of electrical equipment due to its high sensitivity and nondestructive test. In order to provide theoretical basis for the vibration methods, three dimensional models of normal or defective insulators are established in this paper, and modal frequencies of insulators are calculated based on the finite element method under different chamber pressures and different crack sizes. It is shown that doublet modes occur when there are no cracks in basin-type insulators, but there are no doublet modes for insulators with cracks. When compared with the condition that the chamber pressures of both surfaces are the same, the modal frequencies decrease as the chamber pressures of lower surfaces decrease, and the modal frequencies increase as the chamber pressures of upper surfaces decrease. When there are cracks in basin-type insulators, the modal frequencies decrease, and with the increase of the depth of cracks, the decline ranges of modal frequencies increase. These simulation results will no doubt prove the feasibility of using the vibration method to monitor the mechanical condition of basin-type insulators.