【作者】 郑伟；

【导师】 彭新民；

【作者基本信息】 天津大学 ， 水利水电工程， 2006， 硕士

【摘要】 水电站机组的运行特性主要包括三个方面,一是能量特性,即效率问题,二是空化和空蚀特性,三是机组的稳定性。其中,效率特性关系到水能的利用程度,空蚀和空化特性关系到机组的使用寿命,而稳定性则不仅关系到机组的使用寿命而且关系到机组乃至整个电站能否正常运行。同时,由机组振动诱发的水电站厂房结构的振动也已经成为水电站运行和设计的关键问题。在实测信号处理方面,小波、分形等现代处理手段也逐渐显示出其优越性和广阔的发展前景。本文就主要以螺丝湾水电站为例,通过对实测信号的处理分析,分别研究了水力机组的运行特性及水电站厂房结构的振动特性。具体思路和研究内容如下:第一章绪论部分简要介绍了水电站机组振动及厂房结构振动的现状、存在的问题以及未来的发展动态,对本课题所要用到的小波、分形等现代信号处理方法及本课题所要解决的问题进行了归纳和说明。第二章则主要根据实测数据得出水电站原型机组的相对效率,并给出了相应的效率特性曲线。第三章主要结合具体工程实例,通过对机组的振动测试结果分析、轴摆度测试结果分析、水压脉动测试结果分析以及频谱分析,从不同的角度综合评价机组的运行稳定性,指出了机组所存在的各种不平衡因素,给出了可能影响机组运行的各种振源,强调了水力振源是最主要的影响因素,提供了改善机组振动状态的措施并划分出机组的稳定运行区间。第四章旨在运用小波、分形等现代信号处理方法对实测信号进行分析处理,对于实测水压脉动信号首先进行小波分解以确定各频带的能量及其对机组振动贡献的大小;随后又研究了水压脉动的分形特性,指出其在紊流研究中广阔的应用前景;最后在小波消噪的基础上将分形几何应用到水轮发电机组的轴心轨迹识别中去,为计算机图形识别提供了一种有效的工具,也可以作为水力机组振动故障判别的一种方法加以应用。第五章初步讨论了由机组振动诱发的厂房结构振动的特性,从实测的角度揭示了厂房振源,并且通过有限元计算得出主厂房的固有振动特性并进行共振复核;采取不同的荷载施加方式研究了厂房的动力响应,分析了各种施加方式的优点和不足,指出在今后的水电站现场测试中引入对厂房结构振动测试的重要意义。更多还原

【Abstract】 The operation characteristics of Water Turbine Generator Set mainly include energy (output and efficiency), cavitation and stability. Energy is related to extent of water-power utilization; cavitation is related to service life of turbine; the stability not only has great effect to turbine life, but also is directly related to the normal operation of power station. Meanwhile, the vibration of plant structure induced by water-power set has become key problem in designing and operation. Wavelet analysis and fractal geometry have been gradually presenting their advantages and extensive prospect in analysis of measured vibration signal. Basing on actual measurement data of Luosiwan power station, this paper study the operation characteristic of water-power set and the vibration of plant separately. Detailed content and main conclusion of this paper are listed below:In chapter 1, general Situation and existed conditions of vibration of water-power set and plant are introduced, the new method of signal analysis such as wavelet analysis, fractal geometry and the problem to be solved in this paper are summarized.In chapter 2, according to measured data, efficiency of water-power set is received, and corresponding characteristic curve is provided.In chapter 3, combining specific example, set vibration, axis swing, pressure pulsation and spectrum is analyzed, the stability of the water-power set is evaluated, unbalanced factors existed in the set is pointed out, possible excitation sources is obtained, hydraulic excitations as the most important factor is emphasized, measure aimed to improve set operation is provided and stable interval is divided.In chapter 4, wavelet analysis and fractal geometry is used to deal with signal analysis. Energy of frequency range of pressure pulsation and its contribution to vibration are determined by wavelet analysis, and then fractal characteristic of turbulence is illustrated, finally fractal geometry is applied to identification of Shaft central locus of water turbine generator set basing on wavelet purification. It is proved that fractal geometry is an effective method to computer image identification; fractal dimension can also be a way to abstract the symptom of the failures.In chapter 5, plant vibration induced by machine vibration is primary discussed, excitation sources of plant are revealed from view of actual measurement. Natural resonant frequency of main building is calculated by FEM and the resonant reaction is checked, dynamic structure response is analyzed under different application method of loads, and the significance of introducing vibration test of plant structure to field test in hydropower station in future is pointed out.更多还原