互感器振动对GIS超声波局部放电检测的影响

Impact of instrument transformer vibration on GIS ultrasonic-based partial discharge detection

超声波局部放电检测是气体绝缘组合电器(GIS)的重要带电检测方法,但是该方法易受到电气设备机械振动的影响。本文分析了互感器的铁心和绕组等部件的固有振动原理,指出了其主要振动分量为100Hz频率分量,将造成超声检测信号中出现100Hz频率成分,可能被误判为悬浮电位放电。运用希尔伯特-黄变换分析了机械振动引起的GIS超声实测信号,获取了该信号的时频特征;结合现场检测经验,指出了机械振动引起超声局部放电检测异常的综合诊断方法。根据以上分析,提出了使用GIS超声波局部放电检测提高工程安装质量、重视与初始检测结果比较、综合诊断GIS设备的机械振动等相应对策。

Ultrasonic-based partial discharge detection is an important on-line detection method for gas insulated switchgear（ GIS）,but this method is easily affected by mechanical vibration of electrical equipment. The vibra-tions of the iron core and winding in instrument transformer are analyzed in this paper,which points out that the dominant vibration is at 100 Hz frequency. In the ultrasonic-based detection,the appearance of 100 Hz frequency component is usually considered as a signal to indicate the suspended discharge. The time-frequency characteristic of the GIS ultrasonic signal caused by mechanical vibration is extracted with Hilbert-Huang Transform（ HHT）.Combined with the theoretical analysis and field experiences,the impact of mechanical vibrations on the ultrasonicbased detection and its corresponding diagnostic method are presented. Finally,several corresponding countermeasures are presented,including the use of ultrasonic-based detection to improve the installation quality,the comparison of the test results with their initial values and the comprehensive diagnosis of GIS equipment vibrations.