局部放电特高频检测校准影响因素研究

Calibration influence factors of UHF partial discharge detector

局部放电特高频(UHF)法广泛应用于电气设备在线监测,由于UHF信号传递函数的影响因素相当繁复,至今未能实现定量校准。为研究UHF检测技术定量校准的影响因素,分析了典型局部放电源的放电机理,通过试验研究了UHF信号的传播规律以及天线测量特性。研究表明,基于特征参量放电量的UHF检测校准可靠性与放电源有较大关联,电晕放电与悬浮放电的校准曲线更能准确表征设备绝缘缺陷的严重程度,内部气隙放电与沿面放电的准确性则相对较差。UHF信号能量衰减至平稳期所需距离随频率增高而变小,而UHF信号频率变化时不影响传感器在不同角度测量的信号能量衰减变化规律。因此,UHF信号校准必须综合考量具体的放电类型与测量条件。研究结果可为构建UHF校准体系的进一步研究提供参考,对推进UHF法在电力设备故障诊断和绝缘状态评估中的应用具有重要意义。

Ultra high frequency(UHF)partial discharge detection technology has been widely used in on-line monitoring of electrical equipment.However,the calibration of UHF method is still not realized until now,because the influence factors of UHF signal on transfer function are complicated.In order to study the calibration influence factors of UHF partial discharge(PD)detector,the discharge mechanism of typical PD defects is analyzed,and the relative experimental research in propagation characteristics and sensor characteristics of UHF signals are performed.It is concluded that significant difference is found between UHF signal energy and discharge capacity of different discharge source for calibration reliability.The calibration curve of corona discharge and suspended discharge represents the severity of equipment insulation defect more accurately,while the calibration curve of internal air gap discharge and dielectric surface discharge does ineffectively.The distance of UHF signal energy decays to stable period decreases with the increase of frequency,and the decay of UHF signal energy is irrelevant to its frequencies by measuring in different directions.Therefore,in order to calibration the UHF signal,it is necessary to consider the specific discharge type and measurement condition comprehensively.The results provide the favorable reference for further studies to build calibration system of UHF measurement,and promote effective application of UHF method in sensor characteristic fault diagnosis and insulation evaluation of electrical equipment.