交直流复合电场作用下油纸绝缘悬浮放电脉冲波形特征

Characteristics of Floating Discharge Pulse Waveform in Oil-paper Insulation Under AC-DC Combined Electric Field

悬浮放电是换流变压器油纸绝缘中比较常见的一种缺陷形式,由于换流变压器内部电场除单纯交、直流电场外,还存在交直流复合这种比较特殊的电场形式,因此本文结合换流变压器实际运行环境搭建了一套交直流复合局部放电检测平台,采用串联加压法获取了交直流复合电场情况下油纸绝缘悬浮放电的宽带脉冲波形,并提取了波形的时域、频域及时频联合特征。实验结果表明,换流变压器悬浮放电出现了两种截然相反的首波主脉冲放电波形,同时每种波形都具有明显的时、频域特征,该结果可为换流变压器的悬浮放电诊断提供依据。

Floating discharge is a common form of the oil- paper insulation defects in the converter transformer. How- ever, in addition to AC or DC electric field in converter transformer, there also exists special AC - DC combined e- lectric field. Therefore, in this paper, by combining with actual operation environment of converter transformer, a set of AC- DC combined partial discharge detection plat- form was built. The pulse waveform of oil-paper insulation floating discharge under AC - DC combined electric field is obtained by using of series compression method, and the u- nion features of waveform in time domain, frequency do- main and time-frequency domain are extracted. The experi- mental results show that the floating discharge of the con- verter transformer generates first primary pulse discharge waveform with two different forms, and each kind of wave- form has obvious time-frequency characteristics, which can be used to diagnose floating discharge of the converter trans-former.