换流变压器油纸绝缘局部放电及电荷分布特性研究综述

Review on Partial Discharge and Charge Distribution Characteristics of Oil-paper Insulation in Converter Transformer

油纸绝缘作为换流变压器(简称:换流变)阀侧绕组的主要绝缘形式,长期受到交直流复合电压、谐波以及极性反转等复杂工况的影响,其在电场、温度、水分等因素作用下易发生局部放电和空间电荷/界面电荷积聚,从而诱发绝缘介质劣化或击穿。为此从油纸绝缘局部放电及电荷分布特性两方面对国内外研究现状、研究热点和成果进行阐述,总结了不同电压类型、不同老化因素、不同绝缘位置等对油纸绝缘局部放电及电荷分布特性的影响规律,展望了油纸绝缘局部放电特性与机理的研究趋势,指出在极不均匀电场以及谐波、脉冲电压作用下的局部放电特性是未来研究的重点方向,并且需结合电荷分布试验/仿真/分子模拟从宏观和微观角度同时探究电荷分布与局部放电机理的内在联系。这些研究成果的总结可为基于局部放电特征的换流变在线监测技术以及换流变绝缘性能改进提供参考和借鉴。

Oil-paper insulation,as the main insulation of valve side winding,has long been affected by complex working conditions such as AC/DC composite voltage,harmonics,and polarity inversion.Under the action of electric field,temperature,moisture and other factors,it is easy to generate partial discharge(PD)and space charge/interface charge accumulation,inducing dielectric deterioration or breakdown.We summarized the research status,hotspots and achievements at home and abroad from the PD and charge distribution characteristics of oil-paper insulation.The effects of different voltage types,different aging factors and different insulation positions on PD and charge distribution characteristics are analyzed.Finally,the research trend of PD characteristics and mechanism in the future is prospected,and it is pointed out that PD characteristics under the action of extremely uneven electric field,harmonic and pulse voltage are the key research directions in the future,and the internal relationship between PD characteristics and mechanism should be explored at the same time from the macro and micro perspectives by combining charge distribution experiment/simulation/molecular simulation.The summary of these research results can provide references for on-line monitoring technology based on PD characteristics and improvement of insulation performance of converter transformer.