一起发电机转子接地事故分析

某电厂的一台300MW双水内冷发电机,在运行中发生转子接地事故,造成转子绕组绝缘部分烧损、大轴磁化.通过对发电机抽转子后的现场分析和大轴退磁,阐述了可能的事故首发原因和事故发展过程,同时提出为防止类似事故发生应采取的措施.     

汽轮机发电机护环的应力腐蚀

汽轮机发电机护环是固定转子两端绕组，不让转子在离心力作用下向外飞逸的重要结构件。它的应力很高，如200Mw护环设计应力为490MPa，600Mw护环设计应力为690MPa，所以要求护环材料必须是高强度的；又为了减少转子端部的漏磁，所以对于大容量机组的护环都采用稳定性良好的无磁性钢制造，     

发电机转子弯曲振动问题分析与处理

某水电厂水轮发电机组由于运行故障,造成发电机转子塑性弯曲,机组检修后启动振动超标.通过对机组启动、加励磁、升负荷过程振动频谱的监测分析,判断引起振动异常的原因包括原始的弯曲和加励磁后的临时热弯曲.二者相互关联,共同引起机组在升速和带负荷过程中振动幅值的大幅爬升.根据诊断结果确定处理方案,先将发电机转子铣直后重新进行现场平衡,最终将转子的振动控制在合格范围内,彻底解决了振动异常问题.通过对弯曲发电机转子的振动特性分析和处理,分析了转子弯曲情况下的平衡响应变化及热弯曲情况变化等.     

一种小型发电机的可升降定转子自动插装机的设计开发

针对发电机定子与转子装配困难,设计了一种小型发电机的可升降定转子自动插装的机器,重点介绍了小型发电机的可升降定转子自动插装机的总体机械结构设计和相关的自动控制装置,通过控制装置对预定机械结构进行控制继而完成小型电动机定子与转子的装配工作,其机械结构设计合理,相对于手工装配,它能代替人工劳动完成小型发电机定子与转子的装配工作,大大提高了装配效率和装配精度,具有很好的前景。     

无刷励磁发电机转子电流及温度在线检测技术

本文介绍了无刷励磁发电机转子的励磁电压、励磁电流和转子温度的在线检测方法.励磁电压直接通过分压得到,励磁电流则取自轴向线棒两端的压降,而转子温度是基于导电材料的电阻-温度特性通过计算得到.文中阐述了测量原理、系统结构和实验结果,并进行了误差分析.实验结果表明,该系统具有测量精度高,安装方便,运行安全稳定等特点.     

1000MW超超临界汽轮发电机转子的技术特点

介绍了哈电与东芝公司合作生产的迄今最大容量的1 000MW超超临界汽轮发电机转子的特点,该转子在设计和工艺上采用了先进成熟的技术,发电机设计紧凑,结构复杂.效率高,耐热和机械性能可靠.     

海上平台进口发电机转子匝间短路的诊断及其国产化

为解决海上采油平台大型进口发电机组主要部件损坏后出现的严重故障,对其进行国产化翻新意义重大.概括了海上油气平台进口主发电机转子匝间短路的表现形式和诊断方法,初步探讨了发电机转子新线圈的选择和绕制等国产化步骤,阐述了使用新转子后发电机的动平衡调整过程,明显降低了发电机运行振动.研究结果表明,该研究为深入实施进口发电机国产...     

高效发电机的设计

介绍了一种新型的能够提高发电效率的发电机,发电机运行时,内转子和外转子以相反的方向转动,提高了内转子与外转子间的相对转动速度,从而提高了内转子切割磁力线的数量,提高了发电效率和发电量。     

汽轮发电机转子通风试验中应注意的问题

汽轮发电机转子通风试验是检查转子冷却系统是否完好的一种方法,它能发现转子通风道的畅通情况。有时由于试验方法不正确,会给转子通风道造成误判断,影响正常的发电。     

汽轮发电机转子径向通风冷却系统流量分配研究

在转子径向通风冷却系统中,副槽结构、径向风道分布、槽楔出风口直径等参数,直接影响转子风道冷却介质流动特性.为减少转子径向通风系统转子轴向的温差及其热应力,必须使转子沿轴向各径向风道内冷却介质流量分布尽可能均匀.针对转子径向通风冷却系统的结构特点,建立径向通风系统的冷却介质流量分配离散模型.应用该模型对300 MW水-氢-氢汽轮发电机和125 MW空冷汽轮发电机转子径向通风系统进行计算.分析探讨不同转子副槽结构对径向风道流量分配的影响.研究结果表明,采用变副槽结构设计可较好地调整各径向风道流量偏差,且副槽倾斜角存在最优值.研究结果对汽轮发电机转子径向通风系统的设计具有指导意义.     

Empirical study of classification process for two-stage turbo air classifier in series

The suitable process parameters for a two-stage turbo air classifier are important for obtaining the ultrafine powder that has a narrow particle-size distribution, however little has been published internationally on the classification process for the two-stage turbo air classifier in series. The influence of the process parameters of a two-stage turbo air classifier in series on classification performance is empirically studied by using aluminum oxide powders as the experimental material. The experimental results show the following: 1) When the rotor cage rotary speed of the first-stage classifier is increased from 2 300 r/min to 2 500 r/min with a constant rotor cage rotary speed of the second-stage classifier, classification precision is increased from 0.64 to 0.67. However, in this case, the final ultrafine powder yield is decreased from 79% to 74%, which means the classification precision and the final ultrafine powder yield can be regulated through adjusting the rotor cage rotary speed of the first-stage classifier. 2) When the rotor cage rotary speed of the second-stage classifier is increased from 2 500 r/min to 3 100 r/min with a constant rotor cage rotary speed of the first-stage classifier, the cut size is decreased from 13.16 μm to 8.76 μm, which means the cut size of the ultrafine powder can be regulated through adjusting the rotor cage rotary speed of the second-stage classifier. 3) When the feeding speed is increased from 35 kg/h to 50 kg/h, the "fish-hook" effect is strengthened, which makes the ultrafine powder yield decrease. 4) To weaken the "fish-hook" effect, the equalization of the two-stage wind speeds or the combination of a high first-stage wind speed with a low second-stage wind speed should be selected. This empirical study provides a criterion of process parameter configurations for a two-stage or multi-stage classifier in series, which offers a theoretical basis for practical production.     

Flow Field Characteristics of the Rotor Cage in Turbo Air Classifiers

The turbo air classifier is widely used powder classification equipment in a variety of fields. The flow field characteristics of the turbo air classifier are important basis for the improvement of the turbo air classifier's structural design. The flow field characteristics of the rotor cage in turbo air classifiers were investigated under different operating conditions by laser Doppler velocimeter(LDV), and a measure diminishing the axial velocity is proposed. The investigation results show that the tangential velocity of the air flow inside the rotor cage is different from the rotary speed of the rotor cage on the same measurement point due to the influences of both the negative pressure at the exit and the rotation of the rotor cage. The tangential velocity of the air flow likewise decreases as the radius decreases in the case of the rotor cage's low rotary speed. In contrast, the tangential velocity of the air flow increases as the radius decreases in the case of the rotor cage's high rotary speed. Meanwhile, the vortex inside the rotor cage is found to occur near the pressure side of the blade when the rotor cage's rotary speed is less than the tangential velocity of air flow. On the contrary, the vortex is found to occur near the blade suction side once the rotor cage's rotary speed is higher than the tangential velocity of air flow. Inside the rotor cage, the axial velocity could not be disregarded and is largely determined by the distances between the measurement point and the exit.     

Modeling and output tracking of transverse flux permanent magnet machines using high gain observer and RBF neural network

This paper deals with modeling and adaptive output tracking of a transverse flux permanent magnet machine as a nonlinear system with unknown nonlinearities by utilizing high gain observer and radial basis function networks. The proposed model is developed based on computing the permeance between rotor and stator using quasiflux tubes. Based on this model, the techniques of feedback linearization and H_∞ control are used to design an adaptive control law for compensating the unknown nonlinear parts, such as the effect of cogging torque, as a disturbance is decreased onto the rotor angle and angular velocity tracking performances. Finally, the capability of the proposed method in tracking both the angle and the angular velocity is shown in the simulation results.     

双螺杆压缩机转子齿形三坐标测量的半径补偿

双螺杆压缩机转子齿形进行三坐标测量机测量时,需要对球形测头半径进行半径补偿.结合转子螺旋曲面的几何特点,对转子型线测量数据点进行半径补偿计算,得到三坐标测量机球形测头真实接触点,再将空间分布的真实接触点旋转到相同横截面上得到转子型线数据点.通过实例验证该方法的有效性,可以应用于双螺杆压缩机转子型线的检测及逆向工程等工作中.     

An experimental identification model of rotordynamic coefficients of seals using unbalanced synchronous excitation method

This study presents an improved impedance method based on unbalanced synchronous excitation to identify the rotordynamic coefficients of labyrinth seals. The rotordynamic coefficient test is implemented near the cylinder resonance frequency to enlarge the influence of seal force. The force generated by the rotor unbalance is used to provide synchronous frequency excitation for the rotordynamic coefficient test. Four unique equations are set up under two sets of different rotor unbalance conditions to obtain four unknown complex rotordynamic coefficients. The factors that influence the rotordynamic coefficients of seals, namely, unbalance mass, inlet/outlet pressure ratio, and rotating speed, are considered. The dynamic coefficients are minimally affected by different rotor unbalances. The direct items are nearly equal with same signs, whereas the cross-coupled items are nearly equal with opposite signs. All coefficients increase with increasing inlet/outlet pressure ratio and rotating speed. The direct stiffness coefficients increase more quickly than the cross-coupled items. In addition, the effect stiffness and effect damping coefficients are analyzed; results indicate that both coefficients increase with increasing rotating speed.     

电磁激振器电磁力线性度的影响因素研究

导出了电磁激振器电磁力非线性误差公式,提出了非线性的主要原因是由于磁极气隙不均匀的存在,给出了各种工作参数下的误差情况和合适的工作参数范围。     

Nonlinear Dynamic Response of Cylindrical Roller Bearing–Rotor System with 9 Degree of Freedom Model Having a Combined Localized Defect at Inner–Outer Races of Bearing

This article presents a nonlinear dynamic model for a cylindrical roller bearing–rotor system with interaction forces between the inner race, outer race, and roller. Roller–race contacts are modeled predicting nonlinear stiffness (Hertz contact theory) and nonlinear damping for a rotor–cylindrical roller bearing system. Here a shaft–rotor bearing system is modeled with 9 degrees of freedom with one defect on the inner race and one defect on the outer race for a case of combined localized defects. In the mathematical formulation, contacts between rolling elements and inner and outer races are considered as nonlinear springs and nonlinear damping is taken into consideration. Contact force calculations with nonlinearity are solved using the Newton-Raphson method for n unknown nonlinear simultaneous equation. The Newmark-β implicit integration technique coupled with the Newton-Raphson method is used to solve the differential equations. The results are obtained in the form of a time domain plot, frequency domain plot, and phase plot/Poincare map. The validity of the proposed model is compared with experimental results. A bifurcation graph of speed versus peak amplitude predicts the behavior of the system.     

Physics-based recalibration method of cup anemometers

Cup anemometer is the most widely used instrument in the natural environment. However, the accuracy of cup anemometer is not robust due to their inertial structures. In this study, the equation of motion (EOM) relating rotational motion of the cup rotor to aerodynamic force is investigated to reveal the cause of measurement error of cup anemometer. A new methodology is proposed to recalibrate cup anemometer based on theoretical analysis of the dynamic response of the cup rotor and random process theory. The unknown dynamic coefficients of the EOM are quantified by the numerical method using measurement results from inertial and non-inertial anemometers. A detailed example is presented to demonstrate the efficiency of this new method in which coefficients of the EOM are quantified from laboratory and field data. Both mean wind speed and the entire time history could be recalibrated using this new method. Comparing with the non-inertial anemometer results, the improvement rate of the recalibrated cup anemometer results is 29%–99%.     

离心除尘风机单孔试验研究

为给离心除尘风机开发与优化设计提供试验基础,对5-51NO4.5A离心风机蜗壳进行去除蜗板、安装蜗板卡槽和焊接收尘箱体等改造,再用两块薄铁板从蜗板卡槽两端插入形成单个孔,孔的位置可变。按是否延长蜗舌、有无纵向肋分为4种情况,加入40目过筛人造石墨粉体,测试了不同转速下各单孔除尘效率。结果表明:转速增加风量同步增加,而粉体浓度下降,各单孔除尘效率多数轻微降低;沿着蜗壳螺旋线,各单孔除尘效率呈有波折的增大趋势;仅延长蜗舌可以提高各单孔除尘效率4%～10%;安装纵向肋,在未延长蜗舌时单孔除尘效率多数轻微降低,延长蜗舌后多数轻微上升。     

Unbalance vibratory displacement compensation for active magnetic bearings

As the dynamic stiffness of radial magnetic bearings is not big enough,when the rotor spins at high speed,unbalance displacement vibration phenomenon will be produced.The most effective way for reducing the displacement vibration is to enhance the radial magnetic bearing stiffness through increasing the control currents,but the suitable control currents are not easy to be provided,especially,to be provided in real time.To implement real time unbalance displacement vibration compensation,through analyzing active magnetic bearings(AMB) mathematical model,the existence of radial displacement runout is demonstrated.To restrain the runout,a new control scheme-adaptive iterative learning control(AILC) is proposed in view of rotor frequency periodic uncertainties during the startup process.The previous error signal is added into AILC learning law to enhance the convergence speed,and an impacting factor influenced by the rotor rotating frequency is introduced as learning output coefficient to improve the rotor control effects.As a feed-forward compensation controller,AILC can provide one unknown and perfect compensatory signal to make the rotor rotate around its geometric axis through power amplifier and radial magnetic bearings.To improve AMB closed-loop control system robust stability,one kind of incomplete differential PID feedback controller is adopted.The correctness of the AILC algorithm is validated by the simulation of AMB mathematical model adding AILC compensation algorithm through MATLAB soft.And the compensation for fixed rotational frequency is implemented in the actual AMB system.The simulation and experiment results show that the compensation scheme based on AILC algorithm as feed-forward compensation and PID algorithm as close-loop control can realize AMB system displacement minimum compensation at one fixed frequency,and improve the stability of the control system.The proposed research provides a new adaptive iterative learning control algorithm and control strategy for AMB displacement minimum compensation,and provides some references for time-varied displacement minimum compensation.