水电机组励磁控制系统故障诊断研究

发布时间：2018-10-19 17:51

【摘要】：随着我国水电行业硬件方面的不断发展,水电厂对励磁系统的运行效率、使用的安全性和性能的稳定性都有了越来越高的要求。设计优良的励磁设备可以有效的提高水电系统的稳定水平和技术经济指标,对励磁系统进行高效准确的故障诊断和状态评估,有助于励磁系统的安全稳定运行,有助于水电厂提高工作效率、减少人力和时间成本。本文以贵州乌江东风水电厂所使用的EXC9000型励磁系统为研究对象,针对励磁系统中功率柜的核心部分——可控硅整流电路的电路故障及过热故障进行了仿真分析,以可控硅温度为例对励磁系统的运行状态作出评估。具体工作如下:首先,本文在分析了可控硅的物理结构和三相整流电路的电路结构之后,对三相整流桥的导通条件作出了判断。以三相整流桥中不同的可控硅出现故障的情况作为仿真条件,利用Matlab对三相整流故障电路进行仿真。通过总结仿真波形的规律得出通过波形判断三相整流电路可控硅故障类型的方法。进一步,通过人工神经网络模型,以7组不同控制角下单管故障的波形为训练样本,对三相整流电路可控硅故障的具体位置作出判断。随后,针对可控硅容易过热及其温度值很难直接监测的情况,对可控硅进行受热仿真。本文首先分析了可控硅的散热原理、介绍了强迫风冷散热和相变冷却散热的方法。对EXC9000型励磁功率柜的结构进行分析和建模仿真,利用仿真软件Solidworks Flow Simulation对功率柜内的可控硅散热情况进行仿真。针对EXC9000型励磁功率柜配备的两种不同类型的风机分别建模仿真,得出了两个风机仿真效果的对比。为水电厂采取不同散热方法提供了参考意见。最后,采用了模糊层次分析的方法对励磁系统整体进行功能指标层次上的划分,在确定层次分析模型的指标层(底层)元素后,利用模糊数学的概念,以功率柜温度指标为例对励磁系统运行状态作出评估,通过整体状态的评估使得水电厂工作人员可以根据评估的意见更加合理地安排相关检修,从而在一定程度上改善了定期检修所存在的冗余与低效率。
[Abstract]:With the development of the hardware of hydropower industry in China, the efficiency, safety and stability of the excitation system in hydropower plants are becoming more and more important. The design of excellent excitation equipment can effectively improve the stability level and technical and economic index of hydropower system, and carry out high efficiency and accurate fault diagnosis and state evaluation of excitation system, which is helpful to the safe and stable operation of excitation system. The utility model is helpful to improve the working efficiency of hydropower plants and reduce the cost of manpower and time. This paper takes the EXC9000 type excitation system used in Wujiang Dongfeng Hydropower Plant in Guizhou as the research object, and simulates and analyzes the circuit fault and overheating fault of the thyristor rectifier circuit, which is the core part of the power cabinet in the excitation system. The operating state of excitation system is evaluated with SCR temperature as an example. The main work is as follows: firstly, after analyzing the physical structure of thyristor and the circuit structure of three-phase rectifier circuit, the conduction condition of three-phase rectifier bridge is judged. The fault of three phase rectifier is simulated by Matlab. By summing up the law of simulation waveform, the method of judging the fault type of thyristor in three-phase rectifier circuit is obtained. Furthermore, through the artificial neural network model, taking 7 groups of waveform of order tube fault sent out from different control angles as training samples, the location of SCR fault in three-phase rectifier circuit is judged. Then, in view of the overheating of SCR and the difficulty of monitoring the temperature value directly, the thermal simulation of Thyristor is carried out. In this paper, the principle of thyristor cooling is analyzed, and the methods of forced air cooling and phase change cooling are introduced. The structure of EXC9000 type excitation power cabinet is analyzed, and the simulation software Solidworks Flow Simulation is used to simulate the silicon controlled heat dissipation in the power cabinet. According to the modeling and simulation of two different types of fans equipped with EXC9000 excitation power cabinet, the simulation results of the two fans are compared. Some suggestions are provided for different methods of heat dissipation in hydropower plants. Finally, the method of fuzzy analytic hierarchy process (FAHP) is used to divide the whole excitation system into functional index levels. After determining the index layer (bottom layer) elements of the AHP model, the concept of fuzzy mathematics is used. Taking the temperature index of power cabinet as an example, the operating state of excitation system is evaluated. Through the evaluation of the overall condition, the staff of hydropower plant can arrange the relevant maintenance more reasonably according to the assessment opinion. Thus, the redundancy and low efficiency of regular maintenance are improved to some extent.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TV738

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