GIS固体绝缘缺陷所激发特高频信号时频特征研究

Study on Time-frequency Characteristics of UHF Signals Excited by Solid Insulation Defects in GIS

利用特高频局部放电检测方法及时发现并处理气体绝缘金属封闭开关设备(GIS)内部固体绝缘缺陷,是GIS设备运维的重要手段。目前将异常特高频信号与现行标准、规范和典型模拟缺陷图谱进行比对从而诊断缺陷类型及严重程度的方法,因现场情况复杂、设备结构各异,准确性有待进一步提升。因此文中针对现场检测中发现的GIS固体绝缘表面放电缺陷和内部气隙放电缺陷,研究该类缺陷所激发特高频局部放电信号的PRPS统计图谱特征,并利用傅里叶变换和连续小波变换分析单次特高频原始脉冲的频谱特征和时频特征。通过总结各类典型固体绝缘放电缺陷信号的脉冲持续时间、放电次数、相位宽度、极性效应、频域分布和时频特征等变化规律,有助于优化特高频检测频带,提升绝缘类缺陷的检测灵敏度,有利于检测人员更加准确进行放电类型识别和缺陷综合诊断,提升现场缺陷检测和诊断水平。

Detection and treatment of internal solid insulation defects by ultra-high frequency(UHF)partial dis-charge method is an important measure for operation and maintenance of gas insulated switchgear(GIS).At present,the accuracy of the method of comparing abnormal UHF signals with current standards,specification and typical sim-ulation defect atlas to diagnose defect types and severity still needs to be improved due to complex site conditions andvarious structures of equipment.Therefore,in this paper,in view of discharge defects of solid insulation surface andof internal sphere gap of GIS,which is found at site detection,PRPS(phase resolved pulse sequence)statistical spec-trum characteristic of UHF partial discharge signal excited by such type of defect is studied.The spectrum and time-frequency characteristics of single UHF original pulse is analyzed by Fourier transform and continuous wavelet trans-form.The summary of the pulse duration,discharge numbers,phase width,polarity effect,frequency domain distribu-tion and time-frequency characteristics of various solid insulation discharge defect signals can help optimize theUHF detection frequency band,improve the detection sensitivity of insulation defects and can be beneficial for the in-spectors to identify more accurately the discharge type and comprehensively diagnose the defects as well as improvethe defect detection and diagnosis level at site.