变压器油中气泡杂质相局部放电特性研究综述

Review on Partial Discharge Characteristics of Bubble Impurity Phase in Transformer Oil

变压器油道中的悬浮气泡受电磁场、温度场和流场的综合作用,呈现出极其复杂的形态演变、运动规律和放电过程,严重威胁变压器油的绝缘性能,因此研究变压器油中气泡放电机制具有重要意义。目前,国内外学者已在该领域取得了大量的研究成果,该文重点回顾了相关研究人员近二十年对含气泡变压器油局部放电特性的探索,以研究手段为主线,分别从理论分析、仿真模拟及试验测试三个角度对现有成果进行了系统地梳理和论述,研究内容涵盖气泡放电机理与模型、动力学行为及放电试验特性等,但总体来看,含气泡变压器油绝缘失效机制的研究仍面临诸多科学问题与挑战。在此基础上,该文结合分子模拟、多物理场耦合及数字孪生等理论和技术展望了含气泡变压器油绝缘性能的潜在研究方向。

As the core equipment in the transmission and transformation system,large power transformers assume the key role of transforming voltage and transmitting electric energy.However,with the widespread use of large-capacity oil-immersed power transformers,their operating temperature rises and the oil-paper insulation system tends to become more complex,leading to a gradual increase in the chances of moisture in the oil-immersed insulation paper,decomposition of fiber molecules breaking chains and aging of transformer oil insulation,all of which promote the precipitation of suspended bubbles in the oil channel.These bubbles,under the combined effect of electromagnetic,thermal and fluid fields,show extremely complex morphological evolution and movement patterns,resulting in partial bubble discharge and subsequent oil channel breakdown,which has been one of the main factors threatening the insulation performance of transformers.A large number of research results have been obtained by domestic and foreign scholars for the exploration of bubble partial discharge characteristics in transformer oil.It has been shown that the electrohydrodynamic behavior of the gas-liquid two-phase flow in transformer oil and the dielectric discharge mechanism are closely related,and the precise description and quantitative expression of the bubble and transformer oil discharge phenomena and laws require the precise capture of the key characteristic physical quantities in the discharge process.However,the detailed microscopic mechanism of transformer oil insulation failure is still unclear due to the limitations of current scientific and technological means and applied mathematical methods,and thus the discharge evolution of transformer oil containing bubbles cannot be accurately characterized.This paper reviews the research on partial discharge characteristics of transformer oil with bubbles in the past two decades,and systematically reviews and discusses them from three perspectives:theoretical analysis,simulation models and experimental tests,so as to provide some reference for the subsequent in-depth research.First of all,the paper analyzes the theoretical models of bubble discharge in oil proposed by domestic and foreign scholars,and illustrates from three aspects,including the mechanism of partial discharge induced by bubbles in transformer oil,the mechanism of discharge induced by bubbles in transformer oil that has developed streamer,and summarizes the mathematical and plasma models of suspended bubble discharge involved;meanwhile,standing from the perspective of numerical simulation,the paper summarizes the analysis approach and application of bubble dynamic behavior and discharge characteristics,and analyzes the corresponding relationship between the force of bubbles in oil and bubble motion,deformation,coalescence,crushing and splitting in detail.Therefore,starting from the different disciplines,the paper summarizes and analyzes the influence mechanism of various factors on bubble dynamics behavior explored by many scholars through simulation,and carefully analyzes the differences and connections of multi-physical field coupling in bubble dynamics behavior research in different disciplines;in addition,the paper explores the experimental research on bubble motion characteristics and its discharge law at home and abroad,and shows the device platform of the classical experiments,and analyzes the test results mainly from the influence of bubble dynamics on partial discharge in oil and the discharge characteristics of bubbles in transformer oil under different voltage types.Finally,based on the shortcomings of existing research,the paper combines theories and techniques such as molecular simulation,multi-physical field coupling and digital twin to foresee potential research directions for the insulation performance of transformer oil containing bubbles,which provides a certain reference for vigorously promoting the research on the relationship between the electrohydrodynamic behavioral properties of bubbles and the discharge mechanism.