Power transformer insulation systems are subjected to many stresses during normal operation due to lightning and switching.If the spectrum of incoming surge voltage matches the winding one,the corresponding resonance ...Power transformer insulation systems are subjected to many stresses during normal operation due to lightning and switching.If the spectrum of incoming surge voltage matches the winding one,the corresponding resonance will be excited.Therefore external transients occurring in power systems might trigger internal overvoltages with large maximum value in transformer windings.Overvoltages having such characteristic have been the root cause of many power transformer failures.The paper presents an approach to the identification of sensitive zones in the transformer windings based on the measurements of overvoltages inside windings and frequency dependences of admittance of the power transformer.The frequency characteristic of the transformer winding may determine those regions in the frequency spectrum.The presented approach might be used both for design optimization and diagnostics of distribution and power transformers.展开更多
调制传递函数(modulation transfer function,MTF)是目前公认的最为客观、有效的光学镜头检测方法。针对ISO12233刃边法检测数据时存在误差,且抗噪性差的问题,提出了一种系统优化算法流程,通过基于最大类间方差法(Otsu)的Canny算子来提...调制传递函数(modulation transfer function,MTF)是目前公认的最为客观、有效的光学镜头检测方法。针对ISO12233刃边法检测数据时存在误差,且抗噪性差的问题,提出了一种系统优化算法流程,通过基于最大类间方差法(Otsu)的Canny算子来提高边缘检测的准确性和噪声抑制能力;将Bisquare方法代替最小二乘法以减小刃边拟合误差;采用三次Fermi函数求解边缘扩散函数(ESF),解决噪声引起的数据震荡以及离散数据后续处理中的误差问题。实验结果表明,与ISO12233算法相比,优化后的算法更准确,测试精度符合标准,完全满足实际工业生产中镜头检测任务的需求。展开更多
文摘Power transformer insulation systems are subjected to many stresses during normal operation due to lightning and switching.If the spectrum of incoming surge voltage matches the winding one,the corresponding resonance will be excited.Therefore external transients occurring in power systems might trigger internal overvoltages with large maximum value in transformer windings.Overvoltages having such characteristic have been the root cause of many power transformer failures.The paper presents an approach to the identification of sensitive zones in the transformer windings based on the measurements of overvoltages inside windings and frequency dependences of admittance of the power transformer.The frequency characteristic of the transformer winding may determine those regions in the frequency spectrum.The presented approach might be used both for design optimization and diagnostics of distribution and power transformers.
文摘调制传递函数(modulation transfer function,MTF)是目前公认的最为客观、有效的光学镜头检测方法。针对ISO12233刃边法检测数据时存在误差,且抗噪性差的问题,提出了一种系统优化算法流程,通过基于最大类间方差法(Otsu)的Canny算子来提高边缘检测的准确性和噪声抑制能力;将Bisquare方法代替最小二乘法以减小刃边拟合误差;采用三次Fermi函数求解边缘扩散函数(ESF),解决噪声引起的数据震荡以及离散数据后续处理中的误差问题。实验结果表明,与ISO12233算法相比,优化后的算法更准确,测试精度符合标准,完全满足实际工业生产中镜头检测任务的需求。
