不同激励方式下电力电容器振动特性研究

采用试验模态分析方法研究了电力电容器的振动特性。在实验室搭建了1套电容器试验模态分析测试系统,分别采用3种不同激励方式对电容器进行测试。模态参数表明,正弦扫频和白噪声激励的测试结果比脉冲激励精确。一方面规范试验的激励方式,另一方面获得电容器的各主要模态参数,为电容器的低振动、低噪声设计提供依据。     

发电机定子铁心模态振动现场试验方法分析研究

为了防止汽轮发电机组在运行过程中定子铁心椭圆形模态振动频率与双倍的发电机的径向电磁力频率产生共振,必须对汽轮发电机定子铁心进行模态振动试验。结合若干典型汽轮发电机实例,介绍了目前对于电厂停机检修机组进行的发电机定子铁心模态试验的方法及特点,提出了现场试验过程中的注意点。指出发电机铁心模态振动现场测试是目前发电机安全监测工作中很好的技术补充测试手段。     

基于PULSE系统的叶片试验模态识别技术

利用PULSE模态测试系统对某一等截面模拟叶片进行试验模态测量,获得其低阶模态频率、弯曲及扭转振型,将试验模态测量结果与有限元理论模态分析结果进行对比,2种方法的频率识别偏差在2%以内,振型识别结果一致,说明采用该试验模态分析方法可以有效进行叶片模态识别,能应用于工程实践。     

汽轮发电机定子端部绕组模态试验分析

简要论述大型汽轮发电机定子绕组端部模态试验与机组安全稳定运行关系以及简述模态试验的原理和方法,并简要介绍定子端部绕组的振动测试。     

客车车身的模态分析

以某客车企业开发的城市客车车身骨架为研究对象,利用试验模态分析理论研究客车车身振动,采用锤击法对其进行模态测试,获得结构的模态频率、阻尼、振型等模态参数,为改进该客车的车身结构设计提供试验依据和改进思路。     

汽轮发电机定子端部绕组模态试验分析

本文简要论述大型汽轮发电机定子绕组端部模态试验与机组安全稳定运行关系以及简述模态试验的原理和方法,并简要介绍定子端部绕组的振动测试。     

大型汽轮发电机定子绕组端部试验模态分析

本文简要介绍了大型汽轮发电机绕组端部试验模态分析的基本原理、测试系统的组成,测点布置以及 CRAS 模态分析软件的功能与使用;并对东方200MW、300MW、600MW 等大型汽轮发电机绕组端部进行了试验模态分析。     

基于LMS的大型汽轮发电机静叶片座模态分析

以LMS测试系统为基,对大型汽轮发电机静叶片座装配分别进行了自由模态和安装约束模态试验,使得计算模型与约束条件接近于实际工况,实验证明静叶片座的动力特性满足发电机设计运行要求。     

一种风机系统减振分析

本项目通过对风机系统模态和振动测试数据分析,确定了风机系统扭转振动严重是由于风机系统下风机支架扭转刚度较弱,高转速下共振引起;基于风机支架模态应变分布,梳理了风机支架薄弱部位,并针对薄弱部位给出了可加强方案;基于CAE分析了各加强方案对风机支架扭转刚度性能的影响规律,并通过模态和振动测试验证了顶部加斜筋加强方案;结合风机支架加强方案CAE和实验验证结果,对风机支架简化方案主要部件支柱进行了参数优化,给出了相应风机支架简化方案,进行了相应CAE和试验验证。     

空调管路系统模态与应变关系研究

应用有限元方法对空调管路模态进行模拟仿真,通过模态测试验证仿真的准确性,并测试了管路应变,进一步分析了模态与应变的关系,识别出了管路的危险模态,为管路优化设计提供参考。     

模态分析在机械故障诊断中的应用

模态参数识别是模态分析的目标,利用识别出的模态参数对系统进行模态分析。研究了利用模态分析进行故障诊断和状态监测的方法,利用模态分析得到系统的固有频率和振型等参数,可以直观的观察机械设备的动态特性。当设备发生故障时,这些参数也会随之发生变化。根据这些参数的变化情况,可以判断出故障类型,有时还可以判断出故障位置。     

Analysis of factors affecting power system normal form results

This paper discusses the experience in the use of normal form (NF) theory to study nonlinear modal behavior in stressed power systems. Making use of NF theory, we examine the use of several analytical indices to quantify system nonlinear modal interaction and discuss major factors affecting NF results and interpretation. Specifically, the influence of the initial conditions and the effect of strong modal resonance on the normal form analysis is studied. Based on this understanding, heuristic criteria for guessing initial conditions area devised for assessing model adequacy. New insights into the nature of system oscillations are offered and criteria for characterizing nonlinear effects are discussed. The analysis of factors affecting NF results is illustrated on a four-machine two-area test power network. Numerical calculations are presented and discussed to check the accuracy of the method analysis.     

Modal decoupling of overhead transmission lines using real and constant matrices: Influence of the line length

The Clarke’s matrix is a well-known real and constant transformation matrix used for modal transformation in three-phase transmission lines modeling. Although modal analysis has been widely discussed in the technical literature on power system modeling, a new content is approached in this research proving that the approximation using an exact and constant modal transformation matrix depends on both the frequency-dependent parameters and transmission line’s length. As an important conclusion, the approach using the Clarke’s matrix leads to more accurate results considering long transmission lines. There are two methods for modal decoupling in power systems modeling. The first uses only a single constant and real transformation matrix during the entire modeling/simulation routine. The second uses the frequency-dependent transformation matrix for parameters decoupling into the propagation modes and the Clarke’s matrix for mode-to-phase transformation of voltage and current values during simulations. The accuracy of these two modeling/simulation processes are evaluated, in the time and frequency domains, based on results obtained from a reference routine that employs the exact frequency-dependent matrix in modal transformations and numerical transforms for simulation in the time domain. The proposed analysis proves that the accuracy of both methods varies with the line length during electromagnetic transient simulations that leads to peak errors up to approximately 10%. The influence of the line length in modal analysis techniques was not approached in previous references on power system modeling, which represents the original contribution of this paper.     

大型风力机塔筒三维有限元分析

本文采用三维有限元方法,对1.5MW风力机塔筒进行了静强度分析和模态分析,计算了塔筒在极限载荷下的静强度特性,讨论了用于风力机塔筒模态分析的有限元模型的建立原则和方法,针对塔筒的前两阶固有频率,进行了塔筒与风轮、发电机的共振安全性分析,并且分析了地基刚度、塔顶质量对塔筒固有频率的影响,从而为风力机塔筒的优化设计提供了依据。     

Validation of power system non-linear modal analysis methods

The validity of two power system non-linear modal analysis methods, i.e. normal form method and modal series method, are investigated in this work. The second-order participation factors are derived for modal series method and qualitatively compared with that of normal form method. To evaluate the validity of analysis methods, a valid region that satisfies certain error index is defined. The test results of a two-area four-generator power system show that the valid regions of both modal series method and linear modal method are not affected by second-order resonance condition, while that of normal form method is affected significantly. It is found that as the system stress increases, the error index and its growing speed of modal series method are the smallest, and that of normal form method take second place. A non-linearity index for normal form method is defined based on the original index and its validity is verified by the case studies using the same test system.     

多馈入高压直流输电系统的分散协调控制研究

为了提高多馈入直流输电系统的稳定性，该文采用可选择控制结构的部分输出量反馈最优分散协调控制算法设计出了以全系统动态最优为目标的分散协调直流附加控制器，并在设计步骤中引入模态可控程度与模态可观测程度的概念来优选控制器安装地点以及控制反馈信号．从而最大程度地发挥了该控制算法可选择控制结构的特点。算例仿真分析显示了所设计控制器在协调作用下对系统多个振荡模态的良好阻尼效果，证明了该协调控制器设计方法的有效性。     

消除大型汽轮发电机组基础振动的研究方法

概述了大型汽轮发电机组基础振动的研究方法及历史发展，并着重介绍了目前国内外普遍采用的模态分析技术在基础振动研究中的应用。     

多次短路冲击下变压器绕组轴向模态分析

本文中作者定量地计算了在多次短路冲击下变压器绕组端圈所受的应力。针对不同的端圈应力,对变压器绕组进行了模态分析。     

浅析机组轴系扭振时的机械（模态）阻尼

本就机组轴系扭振时无法区分与确定的实际机械阻尼与可测量的模态阻尼之间的关系作了介绍，并就机械模态阻尼的性质，测试方法、测量结果及其变化规律作了阐述，可使教对轴系扭振模态阻尼与实际机械阻尼获得一个初步的概念。     

基于Ansys Workbench的动力电池箱体有限元分析

电池箱足动力电池系统的核心部件,是保证动力电池及其内部器件安全的屏障。本文基于：Proe进行三维建模,采用Ansys Workbench对电池箱在颠簸路况极限载荷下的结构强度,进行有限元分析及优化设计,使箱体的应力分布更为合理,达到提高衔体结构强度的目的。通过模态分析,研究了电池箱在自由状态和预应力状态下的固有频率和振型。结果表明,电池箱的前6阶评论均大于里面激励评论,抗震性能良好。