直流电压下油纸绝缘中载流子输运机理研究

Due to the DC component, space charge can be easily accmulated at the solid-liquid interface between oil-paper insulation in converter transformer. This charge can induce partial discharge and breakdown. For lacking understanding of carriers transport on both sides of the interface, the existing RC model and Wagner model cannot explain the polarity effect, and the discrete simulation model is dependent on the accuracy of selected of parameters, thus revealing the mechanism of charge transport within oil-paper insulation and establishing a corresponding transport model is a key problem to be solved..This project is firstly to setup a combined Kerr- pulse electroacoustic system, which can directly measure charge distribution in liquid and solid medium at the same time. Then space and interface charge properties under different conditions are studied to obtain its dynamics. Thirdly, the carrier transport process within oil and oil-impregnated paper is researched by the measurement of ions migration and conductive feature analysis, to clarify the mechanism of carrier transport through oil-paper. Meanwhile, through the combination of trap property test, microstructure analysis and quantum chemical calculation and so on, surface morphology and trap characteristics on paper surface are studied, and further to reveal the trapping mechanism of different types of carriers at the interface. At last, a model is established based on the carrier motion equations to describe the dynamics of charge accumlation at the interface. This can offer experimental and theoretical guidance for the design of converter transformer.

换流变压器油纸绝缘中的固-液两相界面在直流电压分量下容易积聚电荷并诱发局部放电和击穿。由于界面两侧油纸绝缘中载流子的输运过程尚不清晰，现有的RC和Wagner模型无法解释界面电荷分布极性效应，离散仿真模型又受制于参数的选取，因此揭示油纸绝缘中载流子的输运机理并建立相应的数学模型是一个亟待解决的问题。本项目拟通过建立Kerr效应-电声脉冲法联合测量系统，实现液体和固体介质中电荷分布的同步、直接测量，研究不同条件下油纸绝缘的空间和界面电荷特性，获得空间和界面电荷分布的演化规律，采用电导和液体离子迁移特性分析手段研究载流子的输运特性，阐明油和纸中载流子的形成和输运机制，并综合采用陷阱参数测试、微观形貌分析和量子化学计算等手段研究油纸绝缘表面形态和陷阱特性，揭示油纸绝缘界面处不同类型载流子的捕获机理，进而基于载流子运动方程建立油纸绝缘界面处电荷积聚的数学模型，为换流变压器设计提供试验和理论指导。

换流变压器油纸绝缘中的固-液两相界面在直流电压分量下容易积聚电荷并诱发局部放电和击穿。由于界面两侧油纸绝缘中载流子的输运过程尚不清晰，现有的RC和Wagner模型无法解释界面电荷分布极性效应，离散仿真模型又受制于参数的选取，因此揭示油纸绝缘中载流子的输运机理并建立相应的数学模型是一个亟待解决的问题。本项目拟通过建立Kerr效应-电声脉冲法联合测量系统，实现液体和固体介质中电荷分布的同步、直接测量，研究不同条件下油纸绝缘的空间和界面电荷特性，获得空间和界面电荷分布的演化规律，采用电导和液体离子迁移特性分析手段研究载流子的输运特性，阐明油和纸中载流子的形成和输运机制，并综合采用陷阱参数测试和微观形貌分析等手段研究油纸绝缘表面形态和陷阱特性，揭示油纸绝缘界面处不同类型载流子的捕获机理，进而基于载流子运动方程建立油纸绝缘界面处电荷积聚的数学模型，为换流变压器设计提供试验和理论指导。