引风机变频控制方案的研究与应用

结合韶关发电厂引风机变频改造项目,从摔制角度,介绍了使用高压变频调速装置对引风机进行变频改造的方案和变频改造后引风机变频控制和自动调节的方案。     

高压变频在2×600MW机组发电厂的应用

发电厂静叶可调式轴流引风机的高压变频改造能够从根本上提高综合效益。本文从宁夏大唐国际大坝发电公司的可调式轴流引风机进行高压变频改造的准备工作及技术难题入手,深入地分析了合康高压变频改造过程中对双核DSP控制系统、无速度传感矢量控制技术的选用及主电路的构造。最后,全面地介绍了静叶可调式轴流引风机高压变频改造效果。     

DHVECTOL大功率高压变频器在国产超超临界机组引风机系统中的成功应用

介绍DHVECTOL大功率高压变频器在华中地区首台660MW超超临界机组引风机系统中的变频节能增效情况,结果表明,采用DHVECTOL大功率高压变频器对引风机进行变频调速节能改造,具有投资省、见效快、可靠性高等特点。     

宝应协鑫热电厂引风机高压变频改造分析

对锅炉引风机进行高压变频技术改造,通过对问题提出、变频调速节电原理,并对宝应热电厂改造方案、改造后将取得的经济效益进行详细的闸述.结果表明锅炉引风机进行高压变频技术改造对保证锅炉安全具有十分重要的意义.     

炼钢倒罐站除尘引风机节能技术改造

介绍变频调速节能装置的节能原理,选用高压变频器对引风机进行节能技术改造,运行实践证明具有良好的节能效果。     

HARSVERT-A高压变频器在电厂引风机上的应用

通过对3#炉引风机变频调速改造的介绍,详细叙述了改造的目的、技术方案、改造过程和原理特性.具体分析了改造效果,特别是经济效果,更进一步认识高压变频器在节能降耗方面的作用.     

风机变频器的自动化控制系统设计

为有效解决电厂风机存在风量调节不准确、节流损失大、低效率等缺点,本文在分析高压变频器构成、特点、原理的基础上,采用了Java高压变频器对火力发电厂锅炉风机进行变频调速与改造,设计Java锅炉风机变频调速电气控制系统.运用有关生产系统典型控制理论,构成送、引风机自动控制系统,并融入电厂分散控制系统(DCS),实现锅炉风机...     

垃圾发电厂引风机和鼓风机的变频节能控制

本文介绍某垃圾发电厂引风机和鼓风机的变频节能控制。作者概述了垃圾发电厂的工艺流程;提出了引风机和鼓风机变频节能控制的技术要求;着重描述了风机的变频节能原理和引风机、鼓风机的变频调速控制系统的构成和原理。     

600MW超临界机组引增风机合并后送、引风机故障减负荷试验

介绍了国产600MW超临界机组增压风机、引风机合并改造后送/引风机RB试验,详细描述了送/引风机RB的主要动作要求、二次送/引风机RB试验过程及RB过程中出现异常情况的分析及逻辑完善情况。     

超临界机组送、引风机RUNBACK试验过程及分析

介绍了超临界机组送、引风机RUNBACK的主要动作要求,详细描述了2次送、引风机RUNBACK试验过程及RUNBACK过程中遇到的问题和解决方法,最后给出了一次成功的送、引风机RUNBACK试验结果,并对其结果进行了深入分析。     

具有执行器容错的汽车主动悬架系统有限频率H∞控制

本文研究了一类具有执行器容错的主动悬架系统有限频率H_∞控制问题.运用广义的Kalman-Yakubovich-Popov(KYP)引理,设计了有限频率H_∞控制器.该控制器不仅能够最大程度地减少路面在4～8 Hz范围内对乘客的影响,还能够保证汽车的悬架行程和车轮的动静载之比在它们允许的范围内.因此所设计的有限频率H_∞控制器不仅能够保证汽车驾驶的舒适性还能够保证汽车驾驶的安全性.为了解决系统状态不完全可测的问题,本文采用了动态输出反馈控制器策略.除此之外,在控制器的设计过程中还考虑了主动悬架系统的参数不确定性以及执行器随机故障的现象.最后,本文基于四分之一汽车主动悬架系统验证了控制器的有效性.     

Input-output stability of interconnected systems

New results for input-output stability of multiple input-multiple output systems, viewed as interconnected systems, are established. In the present approach, which can also be utilized in stabilization and compensation procedures, large-scale systems are analyzed in terms of their subsystems and interconnecting structure. The method advanced is applied to a specific example. The present results differ appreciably from earlier ones by Porter and Michel because they are applicable to a larger class of problems, they are simpler to apply when conicity conditions are used, and in addition to circle criteria, they also utilize Popov-type conditions. The present procedure differs significantly from existing methods concerned with the analysis of systems having several nonlinearities. Many of these earlier results (multidimensional Popov criteria) usually involve frequency dependent test matrices and graphical frequency domain interpretations are generally not possible. The present results require frequency independent test matrices and yield graphical frequency domain interpretations.     

变频调速系统电动机启动特性的研究

基于电动机Ｔ 型等效电路,分析了在ＰＷＭ 电压型变频器直接供电条件下,不同启动频率和不同转矩提升电压启动时,电动机启动转矩和启动电流的变化规律,得到了一些简洁有用的公式,由此可确定能够满足电动机启动转矩要求以及变频器功率开关耐流要求的启动频率范围。具有一定的工程参考价值。同时分析了由于高次谐波引起的趋肤效应使定、转子导体电阻阻值显著增加对电动机启动特性的影响     

基于PXI总线的高精度测频系统的设计

为了能够快速准确地测量信号的频率,提高测量精度,搭建了基于虚拟仪器编程语言LabVIEW和PXI总线测试技术的测试平台;介绍了PXI总线,并基于虚拟仪器的设计思想,提出了详细的测频方案,从实际应用的角度出发介绍了一种高精度测频系统的设计与实现;该系统具有操作简单、测试精度高、便于扩展、可移植性强等特点,能够充分满足各种频率信号的测试要求。     

Mixed frequency excitation of an electrostatically actuated resonator

We investigate experimentally and theoretically the dynamics of a capacitive resonator under mixed frequency excitation of two AC harmonic signals. The resonator is composed of a proof mass suspended by two cantilever beams. Experimental measurements are conducted using a laser Doppler vibrometer to reveal the interesting dynamics of the system when subjected to two-source excitation. A nonlinear single-degree-of-freedom model is used for the theoretical investigation. The results reveal combination resonances of additive and subtractive type, which are shown to be promising to increase the bandwidth of the resonator near primary resonance frequency. Our results also demonstrate the ability to shift the combination resonances to much lower or much higher frequency ranges. We also demonstrate the dynamic pull-in instability under mixed frequency excitation.     

Frequency-based underwater terrain segmentation

A method for segmenting three-dimensional data of underwater unstructured terrains is presented. The three-dimensional point clouds are converted to two-dimensional elevation maps and analyzed for segmentation in the frequency domain. The lower frequency components represent the slower varying undulations of the underlying ground. The cut-off frequency, below which the frequency components form the ground surface, is determined automatically using peak detection. The user can also specify a maximum admissible size of objects to drive the automatic detection of the cut-off frequency. The points above the estimated ground surface are clustered via standard proximity clustering to form object segments. The precision of the segmentation is compared against ground truth hand labelled data acquired by a stereo camera pair and a structured light sensor. It is also evaluated for registration error when the extracted segments are used for sub-map alignment. The proposed approach is compared to three point cloud based and two image based segmentation algorithms. The results show that the approach is applicable to a range of different terrains and is able to generate features useful for navigation.     

基于DSP的电液比例方向阀频率特性测控系统设计

针对电液比例方向阀频率特性测试问题,提出了一种基于数字信号处理器(DSP)的电液比例方向阀频率特性测控方案。阐述了测试系统整体结构与工作原理。设计了DSP的硬件系统与软件系统,建立了电液比例方向阀频率特性测试实验系统。在建立的实验台上测试了某电液比例方向阀的频率特性。实验结果表明:研制的基于DSP的电液比例方向阀频率特性测控系统工作可靠,自动化程度高,明显提高了频率特性测试效率。     

一种产生变频多模信号的新方法

直接数字频率合成（DDS)技术是一种新型的频率合成技术,它具有较高的频率分辨率,能快速实现频率切换,又能在频率改变时保证相位的连续性。但是,专用的DDS集成芯片输出波形及频率范围通常是固定的。在研究专用DDS电路构成的基础上,对专用DDS的电路结构进行了扩展,增加了数据分配器和存储不同波形数据的ROM及外围控制电路模块,在大规模可编程FPGA芯片上实现了波形可编程、频率可编程的多模信号变频系统。该变频系统能够实现正弦波、三角波、锯齿波、方波等波形的选择及每种波形频率的变换。系统将PLL倍频、分频电路、数据选择器、数据分配器、频率字输入模块、DDS信号发生器、键控等模块集成在一块可编程FPGA芯片上,这在很大程度上提高了多模变频信号电路的集成度和可靠性。由于FPGA的系统可编程特性,系统实现的参数可通过现场编程调整,增加了电路适配的灵活性。     

An iterative system equivalent reduction expansion process for extraction of high frequency response from reduced order finite element model

An iterative system equivalent reduction expansion process (SEREP) is proposed for extraction of high frequency response from a reduced-order model (ROM) under frequency band-limited excitation. Various model order reduction methods are discussed. To alleviate the present drawback of the SEREP, which requires computation of full system modal matrix, an iterative method based on Sturm sequence check is proposed. The method uses eigenvalue separation properties on the excitation frequency band to identify the optimal number of the eigenpairs required to capture the accurate response. The basic steps for numerical implementation are given. Numerical results are presented to validate the predicted response. Comparison is also made to explain the reasons for the instability of the ROM based on dynamic condensation to capture the high frequency dynamics. Case studies are carried out to demonstrate the effect of the chosen frequency band for response extraction. Also, it is shown that accurate results are obtained while using the proposed method when the chosen frequency band encompass the excitation frequency band.     

基于小波变换和隐马尔可夫模型的人脸识别方法

提出了基于小波变换和隐马尔可夫模型的人脸识别方法。对原始图像采用小波分解后,原始图像被分解到不同的频带上。利用小波理论分析可知,在每一级分解中,低频子图像包含了原始图像的主要描述信息,而其他3个高频子图像包含的信息较少,对模式分类的作用也较小,所以可忽略不计。该算法首先对图像进行3级小波分解,然后把3个不同分辨率的低频子图像由小到大排列成树状结构,形成低频小波树。接着利用主元分析对每个小波树枝进行去相关、降维,形成特征小波树枝,并把它作为观测向量对隐马尔可夫模型进行训练,把优化的模型参数用于人脸识别,实验结果表明,该方法识别率较高,具有很好的发展前景。