基于二次型全局最优控制算法的汽轮发电机组轴系扭振主动控制模拟

把线性定常二次型全局最优控制算法与大型汽轮发电机组轴系扭振理论相结合,以减少轴系扭振能和控制源能量为优化目标,提出了大型汽轮发电机组轴系扭振的线性定常二次型全局最优控制理论,构造了汽轮发电机组轴系扭振主动控制的状态空间方程。阐述了求解离散黎卡提矩阵代数方程的非递推解法,提出利用求解哈密特矩阵特征值问题来确定二次型最优控制反馈矩阵的方法。为了考查扭振主动控制效果,编制了适用于离散系统扭振主动控制的仿真计算程序,利用所编程序对一台200 MW汽轮发电机组轴系进行了扭振主动控制模拟计算,并进行了扭振主动控制的时域特性分析。分析结果表明,采用线性定常二次型全局最优控制理论对汽轮发电机组轴系扭振进行主动控制,不但有很好的减振效果,而且所需控制力矩较小。     

汽轮发电机组扭振模拟机的测试与分析

本文设计了汽轮发电机组扭振模拟机的扭振测试系统，并对模拟机轴系扭振动特性进行了测试与分析。测试结果表明，测试系统配置合理，测试结果准确可靠。通过汽轮发电机组扭振模拟机的轴系扭振动特性参数的测试分析表明，汽轮发电机组扭振模拟机的前几阶扭振固有频率、振型与被模拟对象基本吻合，因此模拟机轴系扭振动特性已达到了预定目标。     

一种汽轮发电机组轴系受迫振动响应分析方法

研究了汽轮发电机组的自由振动以及受迫振动响应问题,并通过特征值与特征向量的求解获得了轴系的固有频率和模态。并针对某型实际汽轮发电机组轴系,获得了该轴系突加载荷时机组的扭转振动响应。     

《机械工程学报》2004年度1-12期总目次

第1期基于12维统计矢量的GMAW焊接过程监测模糊神经网络系统 武传松胡庆肾孙俊生等升船机多钢丝绳受力液压均衡特性研究 彭华伟浩尔顺钟廷修等大型薄板冲压模具毛坯快速制造新技术研究 杨沿平黄智钟志华等现场双经纬仪三维坐标测t系统周畜强张广军江洁等分布式网络化焊接数值模拟系统的研究 赵海燕刘点兵鹿安理等我国干线轨道谱理论分析及试验研究 林建辉陈建政高燕等汽车由路面徽发的演变随机响应预测 赵又群何小明葬孔辉基于连续小波变换的汽轮发电机组轴系扭振及其主动控制 模拟试验的研究张俊红纬军都志勇等利用平面编码器测t巨型转轴…     

300MW汽轮发电机组轴系扭振机电耦合冲击响应的模拟研究

大型汽轮发电机组轴系扭振是发电机机械系统与电网系统相互耦合作用的结果。由于电网负荷变化的随机性,突发性及多样性,机组承受的扭振冲击载荷及其响应特性十分复杂。本文采用弹性连续体振动波动方程的解析方法,分析了300MW汽轮发电机组的扭振响应特性,并针对几种典型的外部激励,对网机耦合作用下机组轴系的扭振强迫振动进行了计算机模拟考核。     

350MW汽轮发电机组轴系振动故障处理

通过对某350 MW汽轮发电机组轴系振动故障的现场观察、数据处理、试验调整以及原因诊断分析,得出是由发电机转子存在旋转性热不平衡引起的振动,即油挡与转子呈柔性摩擦并产生热量,造成转子局部过热弯曲,导致相对轴承振动加大。最后,对故障进行处理,振动恢复正常。此处理过程为解决汽轮发电机组轴系振动故障问题提供了一种值得借鉴的方法。     

汽轮发电机组轴系扭振模拟试验台研制

汽轮发电机组轴系主要承受扭转负荷,因为该轴系的长径比非常大,致使相对扭转刚度降低,从而使扭振固有频率下降,扭转振动危险增高。针对扭转振动的特点研制了扭振模拟试验台,可以模拟发电机组轴系的各种短路、甩负荷、开路运行等工况。试验台由伺服驱动系统、轴系工作台、数据采集系统和载荷发生系统四个部分。试验台的最高转速为8000r/min,载荷发生器可产生周期和冲击激励,传感器采用电涡流位移传感器,采集的数据由计算机软件进行分析处理。     

大型刚性联轴器同轴度的调整研究

汽轮发电机组轴系转子联轴器同轴度和端面平行度的调整,是机组安装、检修过程中一个极其重要的环节。汽轮机运行时,由于支撑轴承的磨损、汽缸和轴承座的位移、轴承垫圈的腐蚀等方面的原因,导致了汽轮发电机组轴系中心会发生同轴度偏差。若偏差过大会产生支撑轴承磨损使轴承温度升高,造成个别支撑轴承负荷过重使机组振动超标、动静部件发生碰擦等故障,所以在检修时一定要对汽轮发电机组轴系联轴器中心进行检测、调整。     

某汽轮发电机组轴系的动平衡处理及研究

以某厂的一台国产２００ＭＷ汽轮发电机组为为例,着重介绍了对国产２００ＭＷ汽轮发电机组轴泵的现场振动分析及动平衡处理的方法、步骤。通过动平衡处理及振动分析,发现了影响该机组轴系泵导振动的各种因素,并提出了改进措施,取得了较好的效果,其结论对类似机组具有一定的启发作用。     

汽轮发电机组轴系扭振及系统扰动对其影响的机理分析

从轴系扭振的基本物理概念出发,阐述了汽轮发电机组轴系扭振的现象与特点,并就电力系统电网中发生的各种扰动对汽轮发电机组轴系扭振的影响的机理进行了分析探讨。     

基于连续小波变换的信号检测技术与故障诊断

通过分析指出,连续小波变换具有很强的弱信号检测能力,非常适合故障诊断领域。从参数离散到参数优化系统研究了连续小波变换的工程应用方法,建立了“小波熵”的概念,并以此作为基小波参数的择优标准。论文最后把连续小波技术应用在滚动轴承滚道缺陷和齿轮裂纹的识别中,诊断效果十分理想。     

PARAMETERS OPTIMIZATION OF CONTINUOUS WAVELET TRANSFORM AND ITS APPLICATION IN ACOUSTIC EMISSION SIGNAL ANALYSIS OF ROLLING BEARING

Morlet wavelet is suitable to extract the impulse components of mechanical fault signals. And thus its continuous wavelet transform (CWT) has been successfully used in the field of fault diagnosis. The principle of scale selection in CWT is discussed. Based on genetic algorithm,an opti-mization strategy for the waveform parameters of the mother wavelet is proposed with wavelet en-tropy as the optimization target. Based on the optimized waveform parameters,the wavelet scalogram is used to analyze the simulated acoustic emission (AE) signal and real AE signal of rolling bearing. The results indicate that the proposed method is useful and efficient to improve the quality of CWT.     

基于复小波变换相位谱的齿轮故障诊断

提出了一种基于复小波变换诊断齿轮故障的新方法。利用Mexican-hat调制复小波基函数对齿轮振动信号进行连续小波变换，再作相位的频谱分析，可以突出边频带结构，识别不同故障模式。试验数据的分析结果表明，该方法适用于齿轮故障诊断，与传统的自功率谱方法以及基于实值小波的小波变换方法相比，这种方法效果更好。     

小波基函数在故障诊断中的最佳选择

通过定性与定量的分析,提出了在对冲击信号进行连续小波变换时选择最佳小波基函数的方法和小波变换 后故障特征提取效果优劣的检验手段,并且得出了对于冲击性信号的连续小波变换,小波基函数的最佳选择为 Morlet函数的结论。     

Analysis of photonic Doppler velocimetry data based on the continuous wavelet transform

The short time Fourier transform (STFT) cannot resolve rapid velocity changes in most photonic Doppler velocimetry (PDV) data. A practical analysis method based on the continuous wavelet transform (CWT) was presented to overcome this difficulty. The adaptability of the wavelet family predicates that the continuous wavelet transform uses an adaptive time window to estimate the instantaneous frequency of signals. The local frequencies of signal are accurately determined by finding the ridge in the spectrogram of the CWT and then are converted to target velocity according to the Doppler effects. A performance comparison between the CWT and STFT is demonstrated by a plate-impact experiment data. The results illustrate that the new method is automatic and adequate for analysis of PDV data.     

基于小波熵的低误报率人体热释电红外信号识别

提出一种基于双密度双树复小波变换小波熵特征的热释电红外(PIR)信号人体识别方法.首先对人体和狗的PIR探测器输出信号进行去噪预处理,然后提取信号的双密度双树复小波变换的小波熵作为特征,最后采用最小二乘支持向量机对特征进行分类.实验结果表明:所提取的特征及分类方法对人体与狗的热释电红外信号的识别率可达93.6%.因此该识别方法能大大降低PIR探测器的误报率,并可进一步提升PIR探测器在安防和智能家居系统中应用.     

连续小波变换在滚动轴承故障诊断中的应用

采用连续小波分析的方法对滚动轴承振动和速度信号进行处理,提取滚动轴承故障特征。通过对滚轴承在正常、内圈剥落、外圈剥落及滚动体落情况下的振动加速度信号进行分析,验证了这种方法的有效性。     

基于同步压缩小波变换的滚动轴承故障诊断

针对滚动轴承故障诊断中存在的非平稳故障信号的特征提取困难这一难题,提出利用同步压缩小波变换(SWT)对故障信号的监测数据进行处理的方法。首先对信号进行连续小波变换(CWT),其次对小波变换系数进行同步压缩变换(SST),然后对SST系数进行自适应阈值去噪,之后在有效信号数据的频率中心附近进行积分提取,最后用提取到的有效信号进行重构。对实测的滚动轴承故障信号进行处理验证,结果表明,SWT具有较高的信号提取精度以及降噪能力,同时具有较高的时频分辨率,能够将故障信号转换为高分辨率的时频谱,弥补了CWT在这方面的不足。     

Precise measurement of defect width in tapered roller bearing using vibration signal

The present experimental investigation is focused on establishing a robust signal processing technique to measure the width of the defect present on the outer or inner race of a tapered roller bearing. An experiment has been designed with roller bearings having various widths of seeded faults, on outer and inner races, respectively. The corresponding vibration signals have been investigated with the proposed method. This method initially denoises the vibration signal using un-decimated wavelet transform. The approximation signal has been shown to be effective for further time–frequency analysis using continuous wavelet transform (CWT). It is not only difficult but ambiguous as well to detect the entry and the exit points of the defect. The ambiguity gets reduced by using Symlet wavelet due to its linear phase nature which maintains sharpness in the signal even when there is a sudden change in signal. In the first phase of the measurement, the scalogram generated from CWT is used to measure the time duration that the roller takes to roll over the defect. However, measurement process is dramatically enhanced with the proposed ridge spectrum, which is generated from the CWT scalogram. The vertical strips drawn on the ridge spectrum corroborates well with defect width. Summarizing, the proposed method can be reckoned suitable and reliable in measuring bearing defect width in real-time from vibration signal.     

IDENTIFICATION OF DIESEL FRONT SOUND SOURCE BASED ON CONTINUOUS WAVELET TRANSFORM

Acoustic signals from diesel engines not only colitain useful information but also includeconsiderable noise components. To extract information for condition monitoring purposes the continu-ous wavelet transform (CWT)is used for the characterization of engine acoustics. The charasteristicsof the CWT in terms of the representation of short duration transient signals are reviewed firstlyWavelet selection and CWT implementation are then detailed. With the wavelet transform, the majorsoures of the exterior radiation sound of the engine front are surveyed. The research provides a reli-able basis for engineering practice to reduce vehicle sound level. Furthermore, the idenification resultsof the measured acoustic signals are compared with the identification results of the measured surfacevibration, and good agreement is observed.