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1.
基于定子电流信号进行异步电机故障诊断时,转子断条和匝间短路故障特征频率分量常常被电流的基频分量淹没,利用小波变换的能量谱对其进行诊断十分必要.考虑到小波分析在时域、频域都具有表征信号局部特征的能力,能通过时频窗的灵活变换来突出信号的不同频率成分;同时还有用小波处理非平稳信号的优越性,计算出各频带所占能量,进而获取能量分布的故障特征.实践表明,通过上述分析并从能量分布的角度出发,可以快速、准确地诊断出电机故障,诊断效果好于傅里叶分析;同时也提供了一种思路,为电机故障在线实时诊断提供了理论依据. 相似文献
2.
Induction motor faults including mechanical and electrical faults are reviewed. The fault diagnosis methods are summarized. To analyze the influence of stator current, torque, speed and rotor current on faulted bars, a time-stepping transient finite element (FE) model of induction motor with bars faulted is created in this paper. With wavelet package analysis method and FFT method, the simulation result of finite element is analyzed. Based on the simulation analysis, the on-line fault diagnosis system of induction motor with bars faulted is developed. With the speed of broken bars motor changed from 1 478 r/min to 1 445 r/min, the FFT power spectra and the wavelet package decoupling factors are given. The comparison result shows that the on-line diagnosis system can detect broken-bar fault efficiently. 相似文献
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吕曙东 《南通职业大学学报》2010,24(4):90-93
根据异步电机的非线性多变量动态数学模型,利用LabVIEW基于数学模型对异步电机进行了仿真研究。通过分析转子断条后电机的等效电路图,得到了故障模型,并将故障诊断方法中的信号处理方法应用于电机故障诊断实例中,对正常电机模型和故障电机模型中的定子电流信号进行处理,且给出了两种信号处理方法的分析结果。仿真表明,此方法对电机故障诊断有一定实效。 相似文献
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研究异步电机转子断条、动态偏心这两种状态下的故障特征,并通过实验室的鼠笼式异步电机转子故障实验系统,对采集的定子电流信号首先通过FFT变换,进行归一化处理,提取出定子电流特征向量;对采集的电机机壳X-Y振动信号则通过db3小波包分析进行去噪处理和频域能量特征向量的提取,实现了故障的分类 相似文献
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Adaptive rotor current control for wind-turbine driven DFIG using resonant controllers in a rotor rotating reference frame 总被引：1，自引：0，他引：1
This paper proposes an adaptive rotor current controller for doubly-fed induction generator （DFIG）, which consists of a proportional （P） controller and two harmonic resonant （R） controllers implemented in the rotor rotating reference frame. The two resonant controllers are tuned at slip frequencies ωslip＋ and ωslip-, respectively. As a result, the positive- and negative-sequence components of the rotor current are fully regulated by the PR controller without involving the positive- and negative-sequence decomposition, which in effect improves the fault ride-through （FRT） capability of the DFIG-based wind power generation system during the period of large transient grid voltage unbalance. Correctness of the theoretical analysis and feasibility of the proposed unbalanced control scheme are validated by simulation on a 1.5-MW DFIG wind power generation system. 相似文献
6.
To improve the accuracy of the stator winding fault diagnosis in induction motor, a new diagnostic method based on the Hilbert-Huang transform （HHT） was proposed. The ratio of fundamental zero sequence voltage to positive sequence voltage after switch-off was selected as the stator fault characteristic, which could effectively avoid the influence of the supply unbalance and the load fluctuation, and directly represent the asymmetry in the stator. Using the empirical mode decomposition （EMD） based on HHT, the zero sequence voltage after switch-off was decomposed and the fundamental component was extracted. Then, the fault characteristic can be acquired. Experimental results on a 4-kW induction motor demonstrate the feasibility and effectiveness of this method. 相似文献
7.
INTRODUCTIONTransmissionlinesofapowersystemaresubjecttomanykindsoffaults.Theprincipaltypesare :phase to earth ;doublephase to earth(phase phase earth) ;phase to phase ;three phase.Followingtheoccurrenceofatransmis sionlinefault,themaintenancecrewmustfinda… 相似文献
8.
An accurate algorithm for fault location of double phase-to-earth fault on transmission line of direct ground neutral system
is presented. The algorithm, which employs the faulted phase network and zero-sequence network as fault-location model in
which the source impedance at the remote end is not involved, effectively eliminates the effect of load flow and fault resistance
on the accuracy of fault location. The algorithm achieves accurate location by measuring only one local end data and is used
in a procedure that provides automatic determination of faulted types and phases, and does not require the engineer to specify
them. Simulation results showed the effectiveness of the algorithm under the condition of double phase-to-earth fault.
Project (No. 023801211) supported by the Key Science Foundation of Tianjin, China 相似文献
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HU Jia-bing HE Yi-kang 《浙江大学学报(A卷英文版)》2006,7(10):1757-1764
INTRODUCTION Due to concerns about emissions from fossil fuels and the depletion of fossil fuel resources, re- newable energy systems are becoming a topic of great interest and investment in the world. In particular, wind energy has been the subject of much recent research and development. In order to overcome the problems associated with fixed-speed wind-turbine system and to maximize the wind energy capture, many new wind farms will employ wind turbines based on Doubly-Fed Induction Ge… 相似文献
11.
Rotor chopper control is a simple and effective drive method for induction motor.This paper presents a novel IGBT chopper topology,which can both adjust rotor resistance and protect IGBT efficiently.Investigation on the quasi-transient state of the rotor rectifying circuit is made,and a nonlinear mapping between the equivalent resinstance and the duty cycle is deduced.Furthermore,the method for determining the magnitude of the external resistor is introduced. 相似文献
12.
以LabVIEW为开发平台,针对航空发动机转子系统的常见故障,利用数据采集卡采集故障信号,结合信号处理中的时频分析方法,设计了航空发动机转子故障诊断系统,并利用转子故障模拟实验器的实验数据验证了该系统的有效性. 相似文献
13.
张莹 《蒙自师范高等专科学校学报》2014,(2):36-38
为了提高异步电机故障诊断的准确性,引入了一种基于模拟退火粒子群算法优化BP神经网络(SAPSO-BP算法)的故障诊断方法.根据电机转子振动频谱中所提取的特征参数与故障类型之间的关系数据,利用模拟退火粒子群算法来优化BP神经网络的权、阈值参数,再由优化好的BP网络进行故障诊断.实验结果表明,该方法具有较好的故障模式的识别效果,明显提高了异步电机故障诊断的准确性. 相似文献
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将样本熵引入旋转机械故障诊断领域,结合形态滤波和样本熵,提出了一种新的转子故障特征提取方法.首先选用最简单的直线结构元素,对实测转子振动信号进行形态滤波降噪处理;然后计算降噪后信号的样本熵,包括转子正常、不平衡、不对中、油膜涡动和碰摩等五种工况的振动信号;最后将样本熵作为特征,对各种故障状态进行评价.转子系统故障诊断的实例验证了该方法的可行性和有效性. 相似文献
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磁悬浮（无轴承）电机利用磁场力使转子悬浮并驱动其实现高速或超高速旋转．基于传统电机技术提出一种交流圆弧电机原理,并按电磁轴承悬浮技术,水平方向对称于转子布置2个圆弧电机,垂直方向对称于转子布置2个圆弧电机,构成交流磁悬浮感应电机;建立电机在干扰作用下转子与定子间的间隙（气隙长度）变化规律,基于电磁理论建立了气隙磁感应强度的分布规律,利用虚位移原理建立电机电磁悬浮力和电磁转矩数学模型;通过有限元分析对磁感应强度、电磁悬浮力和电磁转矩等分布特性进行了仿真研究． 相似文献
17.
Dynamic characteristics analysis of a misaligned rotor-bearing system with squeeze film dampers 总被引：1，自引：0，他引：1
In this paper, a dynamic model is established for a two-stage rotor system connected by a gear coupling and supported on ball bearings with squeeze film dampers (SFDs). The nonlinear dynamic behavior of the rotor system is studied under misalignment fault condition. The meshing force of the gear coupling is calculated considering the deformation of the tooth caused by torque transmission and dynamic vibration. The contact force between the ball and race is computed based on the Hertzian elastic contact deformation theory and the elastohydrodynamic lubrication theory. The supported force of SFD is simulated by integrating the pressure distribution derived from Reynolds’s equation. The equations of motion are rewritten in non-dimensional differential form, and the fourth-order Runge-Kutta method is employed to solve the nonlinear dynamic equilibrium equations iteratively. To verify the validity of the dynamic model and the correctness of the numerical solution method, the experimental power spectra of the rotor system under various misalignment degrees are compared with the analytical results. The effects of several important parameters, such as the lubrication of the ball bearing, the centralizing spring stiffness, the radial clearance of SFD, and the misalignment of gear coupling, on the dynamic characteristics of the rotor system are investigated and discussed mainly focusing on the system stability. The response spectra, bifurcation diagrams, and Pointcaré maps are analyzed accordingly. These parametric analyses are very helpful in the development of a high-speed rotor system and provide a theoretical reference for the vibration control and optimal design of rotating machinery. 相似文献
18.
介绍了基于网形的故障区域判断方法,并论述了配电开闭所和馈线协调配合的故障判断和隔离,给出故障后健全区域优化恢复的方案. 相似文献
19.
针对故障选线问题有许多的研究,提出了许多解决方案,但从现场使用情况看,基于不同原理的选线装置选线效果并不理想。因此,如何可靠的实现故障自动选线,有必要对其进行更深入的研究。本文针对传统小波变换在故障选线中的优缺点分析,提出一种基于小波包多频带相关分析的故障选线新方法。通过对各线路暂态零序电流进行一系列变换,得到各线路的故障测距系数,并按大小排序,其中最小值对应的线路即为故障线路。PSCAD仿真验证该方法正确有效。 相似文献
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文章针对现行规范中断层带在缺乏系统有效的历史监测数据情况下,只是笼统的给出拟建建筑离开断层带的"避让距离",导致建筑用地的浪费和影响城市规划的统一性,没有区别对待一些特殊问题这一情况,提出了对断层评价与处理新的方法和基本原则,旨在对待建建筑工程的规划与设计有所帮助。 相似文献