稍不均匀电场下硫化亚铜对油纸绝缘局部放电影响机制

Mechanism of the Effect of Copper Sulfide on Partial Discharge of Oil Paper Insulation under Slightly Uneven Electric Field

变压器油中的腐蚀性硫与铜绕组反应产生的硫化亚铜(Cu_(2)S)与电力变压器局部放电现象密切相关。研究了Cu_(2)S沉积条件下油纸绝缘局部放电的发展过程及其影响规律。将油中流体动力学漂移扩散模型和纸中的双极型载荷子传输模型结合应用于柱板电极几何模型下,获得了稍不均匀电场环境中Cu_(2)S沉积下的油纸绝缘局部放电过程云图。随着施加电压升高,柱电极附近的油分子最先电离产生正离子和电子,随后沉积附近的油分子开始电离。Cu_(2)S沉积厚度增加会导致油隙中的电场强度增加,加剧放电现象,产生较高的局部电荷密度,Cu_(2)S沉积宽度增加利于电荷的扩散。研究揭示了稍不均匀电场下Cu_(2)S沉积引发局部放电的物理机制和作用规律,为进一步提出Cu_(2)S沉积放电的抑制技术提供理论参考。

The reaction of corrosive sulfur present in transformer oil with the copper winding results in the formation of copper sulfide(Cu_(2)S),and this process is intimately associated with the occurrence of partial discharge(PD)phenomena in power transformers.The development process of partial discharges in oil-paper insulation under Cu_(2)S deposition conditions and its influencing laws were investigated.A hydrodynamic drift-diffusion model and a bipolar charge-carrier transport model were combined to analyze the development of PD under cylindrical plate electrode geometries.Charge density cloud maps of PD processes in oil-paper system under Cu_(2)S deposition in slightly inhomogeneous electric field conditions were obtained.As the applied voltage increases,the oil molecules near the column electrode were first ionized into positive ions and electrons,and then the oil molecules near the deposition begin to be ionized.An increase in the thickness of Cu_(2)S deposits leads to an elevation in the electric field strength within the oil gap,subsequently exacerbating the discharge phenomenon and resulting in a greater local charge density.The wider deposition of Cu_(2)S promotes the diffusion of charge along its surface.The study has revealed the physical mechanisms and operating laws underlying the PD induced by Cu_(2)S deposition in a slightly inhomogeneous electric field,thereby providing a theoretical reference for the further development of suppression techniques for Cu_(2)S deposition-related discharges.