基于时-相合成谱图的电力电容器薄膜局部放电模式识别方法

Partial discharge pattern recognition method for power capacitor film based on time-phase synthesis spectrogram

局部放电类型与电力电容器薄膜早期绝缘劣化程度密切相关,对局部放电类型的准确识别将有效改善电容器的运行状态和保障电网安全。本文设计了金属化薄膜电容器中易产生的薄膜间尖端缺陷、气隙缺陷和沿面缺陷模型,分析了电容器薄膜局部放电的时间序列谱图和相位分布谱图特性及平均放电量Q和放电重复率F的发展规律。将Q和F的变化曲线取点拟合,并与局部放电信号进行相关性分析,将相关性系数作为时域特征量。提取局部放电相位分布谱图的正负半周偏斜度、正负半周陡峭度和正负半周不对称度作为相位特征量。提出了一种基于时-相合成雷达谱图的电力电容器薄膜局部放电模式识别方法。通过对合成谱图中特征量封闭图形外接矩形的重心坐标进行聚类分析,利用重心坐标分布的象限对薄膜局部放电进行模式识别。结果表明:该方法相较于传统的单一谱图模式识别准确率更高,为电容器设备的在线监测和故障诊断提供了理论依据。

Partial discharge type is closely related to the early insulation deterioration degree of power capacitor film.The accurate identification of partial discharge type will effectively improve the operation state of capacitor and guarantee the safety of power grid.In this paper,the models of inter-film tip defects,air gap defects,and surface defects generated easily in metallic film capacitor were designed.The time series and phase distribution spectra characteristics of partial discharge in capacitor film and the development of average discharge quantity Q and discharge repetition rate F were analyzed.The curves of Q and F were fitted with points,and the correlation between them and partial discharge signal was analyzed.The correlation coefficient was taken as the characteristic parameter of time domain.The skew,steepness,and asymmetry of partial discharge phase distribution spectra were extracted as phase characteristic parameters.A partial discharge pattern recognition method of power capacitor film based on time-phase synthetic radar spectrum was proposed.The barycentric coordinates of the enclosed rectangle of characteristic parameters closed graph in the synthesis spectrogram were conducted cluster analysis,and the distribution quadrants of barycentric coordinates were used to recognize the partial discharge pattern of film.The results show that the method has more pattern recognition accuracy than the traditional single spectrum,which provides a theoretical basis for online monitoring and fault diagnosis of capacitor equipment.