电力变压器油纸绝缘热解过程微观机制研究

发布时间：2018-08-05 12:54

【摘要】：电力变压器作为电力系统中电压变换、电能分配及电能传输的核心设备,其正常运行是保证电力系统安全、可靠、稳定运行的关键。变压器一旦发生事故将造成巨大经济损失,甚至导致严重的社会影响。为此,深入理解变压器油纸绝缘的裂化机理,有效地诊断和评估变压器内部潜伏性故障,对于预防和降低故障的发生几率,保障电力系统的可靠运行,具有十分重要的理论意义和现实价值。在全面了解电力变压器油纸绝缘裂解产气机理研究现状的基础上,本文通过引入热力学理论与分子模拟技术,重点研究了油纸绝缘热解过程的微观机制,揭示油纸绝缘材料微观变化和宏观性质之间的联系,探索表征故障严重程度的新指标,所取得的创新性成果主要包括：1.引入热力学中的焓变理论,通过计算有代表性的变压器矿物油产气化学反应的焓变量,得到DGA故障气体的生成能量,从能态角度建立了评估电力变压器过热故障严重程度的新判据；2.引入基于键级表达的ReaxFF反应力场,分别对变压器液体绝缘——矿物油和植物油分子模型,进行高温热应力下的反应分子动力学模拟,探索绝缘油热解过程的微机理。采用元素追踪法统计分析了绝缘油分子模型高温裂解的轨迹文件,明确了其的初始裂解机理以及主要产物的差异性,厘清了主要产物的生成机制；通过对裂解反应进行反应焓变的计算,明确了绝缘油裂解产物的种类和数量与微观化学键能的相关性,揭示了绝缘油裂解过程中能量变化规律。3.引入基于ReaxFF反应力场的分子模拟技术和基于py-GC/MS的现代化学分析技术,对变压器固体绝缘——绝缘纸,进行了高温热应力下的仿真模拟与实验研究,探索绝缘纸在热解过程中的微观机理。通过理论与实验的相互验证,明确了绝缘纸的初始裂解机理以及主要产物的生成机制；从原子层面研究绝缘纸裂解产气的微观动态机理,为故障诊断提供微观特征参量。
[Abstract]:Power transformer is the core equipment of voltage conversion, power distribution and power transmission in power system. Its normal operation is the key to ensure the safe, reliable and stable operation of power system. Once transformer accident happens, it will cause huge economic loss and even serious social impact. Therefore, understanding deeply the cracking mechanism of transformer oil-paper insulation and effectively diagnosing and evaluating the latent faults inside the transformer can prevent and reduce the probability of failure and ensure the reliable operation of power system. It has very important theoretical significance and practical value. On the basis of a comprehensive understanding of the present situation of gas production mechanism of oil-paper insulation pyrolysis in power transformers, the microcosmic mechanism of oil-paper insulation pyrolysis process was studied by introducing thermodynamics theory and molecular simulation technology. The relationship between microscopic changes and macroscopic properties of oil-paper insulating materials is revealed, and a new index to characterize the severity of faults is explored. The innovative results obtained mainly include: 1. By introducing the enthalpy variation theory in thermodynamics and calculating the enthalpy variables of the typical gas reaction of transformer mineral oil, the formation energy of DGA fault gas is obtained. A new criterion for evaluating the severity of overheating faults of power transformers is established from the point of view of energy state. The ReaxFF reaction force field based on bond level was introduced to simulate the reaction molecular dynamics of transformer liquid insulated mineral oil and vegetable oil respectively under high temperature thermal stress, and the micromechanism of insulation oil pyrolysis process was explored. The trace file of high temperature pyrolysis of the molecular model of insulating oil was analyzed by elemental tracing method. The initial cracking mechanism and the difference of main products were clarified, and the formation mechanism of the main products was clarified. Through the calculation of the reaction enthalpy change of the pyrolysis reaction, the correlation between the type and quantity of the pyrolysis products of insulating oil and the micro-chemical bond energy is clarified, and the law of energy variation in the pyrolysis process of insulating oil is revealed. By introducing the molecular simulation technology based on ReaxFF reaction force field and the modern chemical analysis technology based on py-GC/MS, the simulation and experiment of transformer solid insulation-insulator paper under high temperature thermal stress were carried out. To explore the microcosmic mechanism of insulation paper during pyrolysis. Through the mutual verification of theory and experiment, the mechanism of initial pyrolysis and the generation of main products of insulator paper are clarified, and the microscopic dynamic mechanism of pyrolysis gas production of insulator paper is studied from the atomic level, which provides the microscopic characteristic parameters for fault diagnosis.
【学位授予单位】：华北电力大学(北京)
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TM855

【相似文献】