变压器特高频、超声波侵入式PD联合检测技术

最新颁布的IEC TS 62478-2016《高电压技术-电磁和声学法测量局部放电》国际标准,指出了现有的外置式超声波法测量PD主要存在:设备外壳对声波的衰减和不同介质声阻抗引起的传输多路径问题。笔者基于变压器放油阀结构,将特高频(UHF)天线和压电陶瓷声发射(AE)传感器进行一体化设计,再考虑电磁波和超声波信号耦合、防变压器油渗漏两个主要问题的基础上,加工研制了能够同时耦合UHF、AE信号的侵入式PD复合传感器。110 kV变压器内置尖端放电下与外置式压电陶瓷AE传感器的对比试验表明:所设计的UHF、AE侵入式PD复合传感器能够有效探测到油中微弱放电产生的具有特定时间差Δt的电磁波和超声波信号,这为变压器PD检测提供了一种全新的"声-电"即UHF、AE联合检测技术。

Combined Intrusive PD Detection Technology with UHF and AE Methods for Transformer

In the latest international standard IEC TS 62478-2016 "High voltage test techiques-measurement of partial discharges by electromagnetic and acoustic methods",it is pointed out that the existing external ultrasonic method for PD measurement mainly exists in the attenuation of acoustic wave from the equipment shell and the multipath transmission problem caused by acoustic impedance of different media.Based on the structure of transformer oil valve,the UHF antenna and piezoelectric ceramic acoustic emission(AE) sensor are integrated.Considering the coupling of electromagnetic and ultrasonic signals and the leakage prevention of transformer oil,an intrusive PD composite sensor capable of simultaneously coupling UHF and AE signals is developed.The comparison test with a110 kV transformer between the built-in composite sensor and the external piezoelectric ceramic AE sensor shows that the designed PD composite sensor can effectively measure the UHF and AE signals with a certain time difference At from weak discharges in oil,which provides a new"acoustic-electrical" combined detection technology for PD in tran sformer.