摘要
过热性故障（又称热故障）是影响充油设备稳定运行的两大关键因素之一。加强充油设备过热性故障的研究，不仅能及时发现充油设备的热故障，还能及时避免热故障向电故障转化，在整体上降低充油设备故障发生率。以油浸变压器为例，内部油—纸绝缘结构故障温度最高可达到1000℃以上。过热故障点释放出的能量会破坏变压器油的化学键，造成变压器油分解生成低分子烃类气体以及氢气等，并溶于变压器油中。本文从热故障下矿物油热解机理和实验模拟两个角度，首先采用反应分子动力学模拟的方法研究了矿物油的热解过程及产气规律；其次研制了热故障下矿物油分解的实验模型并进行了实验研究，为故障类型和故障严重程度的诊断提供理论支持。本文主要研究内容为： ①采用基于ReaxFF(reactive force field)力场的反应分子动力学模拟方法建立了含有30个分子的矿物绝缘油（简称矿物油）仿真模型，深入研究了不同温度下矿物油的动态热解过程和产气规律。通过Reactive-MD-analysis识别模块对矿物油热解产物的识别和统计，结合仿真的动态图像，分析了矿物油的微观反应过程，得出了矿物油热解的主要反应路径以及小分子气体的生成路径。
②分析了温度和时间对热解微观过程的影响以及伴随的能量变化。通过仿真结果与改良三比值法和热重差分实验不同角度的对比，验证了仿真结果的合理性，表明ReaxFF 反应动力学模拟为从分子上研究矿物油的热解提供了一种有效的途径。
③以变压器热故障实体模型为依据，研制了变压器等充油设备热故障下矿物油热解实验模拟装置，对发热体、箱体、温度控制及测量、气体测量以及功率测量等模块进行了设计，通过输入功率控制及多路温度传感器实现对温度的精确控制和实时测量，并通过功率计对反应能量进行了测量。通过COMSOL有限元仿真软件模拟了热故障下装置内的温度场，和实际变压器内温度场对比，验证了实验模拟装置设计的合理性和可靠性，从而实现对局部过热故障产生及发展过程的实验模拟。
④研究了热故障下矿物油热解实验模拟装置内的温度场分布和气体产生情况随热源表面温度、热源发热时间、热源功率以及热源产生能量的变化，分析了温度、时间、功率和能量对于矿物油热解的影响规律。并定性划分了矿物油热故障分解区域，为热故障的诊断提供理论依据。
关键词：过热故障；矿物绝缘油；ReaxFF；设备模拟；COMSOL；温度场
ABSTRACT
Overheating fault is one of the two major faults in the oil filled equipment such as transformer. So the study of overheating fault in oil filled equipment, can not only discover the thermal fault of oil filled equipment, can also avoid the conversion from thermal fault to electricity fault in time, to reduce the incidence of fault in oil filled equipment on the whole. In oil-immersed transformer, for example, maximum temperature of fault in the internal oil-paper insulation structure is above 1000℃. Energy r
eleased by thermal fault point will damage chemical bonds in transformer oil molecules, causing decomposition of big hydrocarbons to low hydrocarbons molecules gas and hydrogen gas which will dissolve in transformer oil. From mineral oil pyrolysis mechanism under thermal fault and experimental simulation two aspects, this paper, first of all, used the reactive molecular dynamics simulation method to study the law of the pyrolysis process of the mineral oil and the law of gas generation, and then, thermal fault was developed under the experimental model. And by the way, experimental research of mineral oil decomposition was developed to provide the theoretical foundation for fault diagnosis, such as fault type and the severity of fault. In this paper, main work is as follows:
①Based on ReaxFF (reactive force field), in this paper, the reactive molecular dynamics(MD) simulation method was used to establish the simulation model of mineral insulating oil molecules under different temperatures and to study dynamic pyrolysis process and produce regularity of gaseous molecules in mineral insulating oil. Through the dynamic images in the simulation process and the analysis for the pyrolysis products of mineral insulating oil under different temperatures and time by a Reactive-MD-analysis model, the microcosmic reaction process of insulating oil was analyzed, and the pyrolysis reaction path and the production path of small molecules were concluded.
电暖画
②Focus was fixed on the effect of temperature and time on the micro process and the energy change in the pyrolysis process. By comparisons with the improved three ratio method and the TG-DSC test in different ways, this paper proved the rationality of the simulation results. And ReaxFF molecular dynamics simulation provided an effective way to study the pyrolysis of the mineral insulating oil.
③Developed a thermal fault simulator of oil filled equipment such as transformer.
Based on the transformer entity model mainly transformer device, the simulation is mainly consist of heating element, box, temperature control module, temperature measurement module, gas measurement module, and power measuring module. It can ensure the precision of temperature control through voltage regulation power, realize the all-round real-time measurement of temperature through temperature sensor with many roads, and achieve energy measurement through the power of control. Through finite element simulation software COMSOL the temperature field under the thermal fault inside the device was simulated, and comparison with the temperature field in the actual transformer, the rationality and reliability of the simulating experiment device was verified, so as to realize simulation of emergence and development process of thermal fault.
④The temperature field distribution and the rule of the gases during the development process of the thermal fault in the device were studied. Through the measurement of temperature field and the observation of gases generation in the heating process, temperature field distribution and the rules of gases generation were studied with the change of surface temperature, heating time, power of heating element and energy generated by the heat source. And then the impact of temperature, time, power and energy had on pyrolysis of mineral insulating oil were analyzed. The research of pyrolysis mechanism and decomposition simulation experiment device of mineral insulating oil under the thermal fault provided a theoretical basis for thermal fault diagnosis.
Key words:Thermal fault; Mineral insulating oil; ReaxFF; Device simulation;
COMSOL; Temperature field
定鼎建筑目录
目录
中文摘要.......................................................................................................................................... I 英文摘要....................................................................................................................................... III 1 绪论.. (1)
1.1 课题研究背景和意义 (1)
1.2 国内外研究现状 (4)
1.2.1 基于热力学的矿物油热解理论 (4)
1.2.2 基于分子模拟的矿物油热解理论 (8)
1.3 论文研究内容 (9)
2 矿物油热解反应分子动力学模拟研究及验证 (11)
激光快速成型机
2.0 引言 (11)
2.1 分子动力学模拟基础 (12)
2.1.1 分子模拟力场和系统 (12)
2.1.2 分子模拟方法 (13)
2.2 矿物油反应分子动力学仿真建模 (14)
2.2.1 矿物油反应分子动力学仿真力场—ReaxFF (15)
2.2.2矿物油反应分子动力学仿真步骤 (15)
2.3 矿物油反应分子动力学仿真结果分析 (17)
2.3.1 矿物油的热解产物 (17)
2.3.2 模拟温度对矿物油分解产物的影响 (19)
2.3.3 模拟时间对矿物油分解产物的影响 (21)
2.3.4 矿物油热解产物随系统吸收能量的变化 (23)
2.3.5 矿物油热解过程分析 (24)
2.4 热重差分实验对仿真结果的验证 (26)
2.4.1 热重差分实验步骤 (26)
2.4.2 热重差分实验结果分析 (26)
水下呼吸器
2.4.3 仿真结果与热重差分实验结果的对比 (27)
2.5 本章小结 (28)
3 矿物油热故障分解实验模型及温度场仿真研究 (31)
3.1 引言 (31)
3.2 矿物油热故障分解模拟装置设计 (31)
3.2.1 箱体设计 (31)
3.2.2 故障发热源设计 (33)
3.2.3 测温装置设计 (36)
3.2.4 控温装置设计 (38)
3.2.5 功率测量设计 (39)
经络油3.3 矿物油热故障分解模拟装置温度场仿真 (40)
3.3.1 有限元模拟软件COMSOL概况 (40)
3.3.2 温度场仿真模型建立 (41)
3.3.3 温度场仿真结果分析 (42)
3.4 本章小结 (45)
4 矿物油热故障分解实验研究 (47)
4.1 引言 (47)
4.2 试验步骤 (47)
4.3 油中溶解气体检测 (49)
4.4 温度场分布测量 (50)
4.5 矿物油热解影响因素分析 (52)
字幕烟花
4.5.1 热源温度对矿物油热解的影响 (52)
4.5.2 热源发热时间对矿物油热解的影响 (54)
4.5.3 热源功率对矿物油热解的影响 (57)
4.5.4 热源产能对矿物油热解的影响 (60)
4.6 矿物油热解反应分子动力学仿真与实验结果对比分析 (65)
4.7 本章小结 (66)
5 结论与展望 (69)
5.1 结论 (69)
5.2 展望 (69)
致谢 (71)
参考文献 (73)
附录 (77)
A. 作者在攻读学位期间发表的论文 (77)
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