换流变压器油纸绝缘局部放电特性与机理研究及绝缘状态评估

The voltage environment of converter transformer is complex, and partial discharge (PD) has more threats to the oil paper insulation. Therefore, the characteristics of PD under complex voltage need an intensive study. The accurate PD theory and model, as well as the reliable insulation condition assessment system need be set up urgently. In this project, the PD characteristics of oil-paper insulation including time-frequency characteristic, waveform characteristic, spectrogram characteristic, energy and entropy characteristic under complex voltage are studied. The fast PEA and AC phase matching technology are applied in order to measure the space charge under complex voltage, combined with the charge distribution model in oil-paper insulation based on simulation, the charge distribution regularity of oil-paper insulation under complex voltage is studied. Thereby the internal relations between PD and charge distribution are discussed, and the accurate theory of PD under complex voltage is set up based on the internal relations. According to different PD patterns, PD development stages, and oil-paper aging degrees, the comprehensive, effective and innovative spectrograms are drawn, then some multi-dimensional PD features are extracted, finally, the reliable oil-paper insulation condition assessment system is set up, which can implement the defect degree diagnosis, discharge sources detection, separation and identification, insulation aging evaluation. This project can provide theoretical bases for PD mechanism; can provide reliable foundations for insulation design of converter transformer; can provide key assessment technology for on-line monitoring of converter transformer.

由于换流变压器所处电压环境复杂，局放对其油纸绝缘的威胁更大，因此，复杂电压下的油纸绝缘局放特性需深入全面地研究，准确的局放理论与模型、可靠的绝缘评估系统亟待建立。本项目拟研究复杂电压下油纸绝缘局放的时频特性、波形特性、谱图特性、能量特性及熵特性；运用快速PEA测量法与交流相位匹配技术，实现复杂电压下油纸绝缘电荷分布的测量，结合基于仿真的油纸绝缘电荷分布模型，研究复杂电压下油纸绝缘电荷分布规律，从而探究局部放电与电荷分布的内在联系，根据电荷分布规律建立准确的复杂电压下油纸绝缘局放理论；针对不同的放电模式、放电发展阶段，油纸老化程度，绘制更全面有效的新型谱图，提取多维度的新特征量，建立可靠的绝缘状态评估系统，实现绝缘缺陷发展程度诊断，多局放源检测、分离、识别，油纸老化程度评估。本项目为油纸绝缘局放机理提供理论基础，为换流变压器的绝缘设计提供可靠依据，为换流变压器绝缘状态在线监测提供关键技术。

由于换流变压器所处电压环境复杂，局放对其油纸绝缘的威胁更大，因此，复杂电压下的油纸绝缘局放特性需深入全面地研究，准确的局放理论与模型、可靠的绝缘评估系统亟待建立。本项目拟研究复杂电压下油纸绝缘局放的时频特性、波形特性、谱图特性、能量特性及熵特性；运用快速PEA测量法与交流相位匹配技术，实现复杂电压下油纸绝缘电荷分布的测量，结合基于仿真的油纸绝缘电荷分布模型，研究复杂电压下油纸绝缘电荷分布规律，从而探究局部放电与电荷分布的内在联系，根据电荷分布规律建立准确的复杂电压下油纸绝缘局放理论；针对不同的放电模式、放电发展阶段，油纸老化程度，绘制更全面有效的新型谱图，提取多维度的新特征量，建立可靠的绝缘状态评估系统，实现绝缘缺陷发展程度诊断，多局放源检测、分离、识别，油纸老化程度评估。本项目为油纸绝缘局放机理提供理论基础，为换流变压器的绝缘设计提供可靠依据，为换流变压器绝缘状态在线监测提供关键技术。