Study on Electromagnetic Force and Vibration of Turbogenerator End Windings under Impact Load(Ⅱ): Analysis of Vibration of End Windings under Impact Load

On the basis of the study of transient eddy current field in the end region of turbogenerator and electromagnetic force of end region winding, this paper analyzes the electromagnetic vibration of the turbogenerator roundly. A 320 MW turbogenerator is taken as an example to specify the electromagnetic force of end region winding and therefore the vibration in the case that the generator is affected by impact load. Some conclusions are drawn on the basis of the specification. Vibration of windings under imaginary faults is simulated, so that the vibration law of the end winding of turbogenerator can be studied further. On the basis of this, the countermeasure against winding vibration can be advanced.

Study on Electromagnetic Force and Vibration of Turbogenerator End Windings under Impact Load(Ⅰ): Analysis of Electromagnetic Force of End Windings under Impact Load

In this paper, the boundary value problem (BVP) of 3 D transient eddy current field in the end region in the case that the generator is affected by impact load is specified. Besides, ways to implement discrete methods in both time domain and space domain during the solution of the problem are investigated. The Crank Nicolson scheme is utilized to attain the iterative format of time differential, after taking factors that can ensure both computation precision and stability into consideration. In this paper, the magnetic distribution in the end region of a turbogenerator in the case that the generator is affected by impact load is specified. As a result, it provides foundation for further study of electromagnetic force and electromagnetic vibration in the end region of the turbogenerator.

Retrospect and Prospect of Excitation Systems of Large Size Turbogenerators

This paper briefs the developmental course, manufacturing and applications, as well as future prospect of excitation systems of large size turbogenerators in China, emphatically expounds the advantages of seif-excitation systems with potential source reetifiers and matters needing to be noted during dissemination and application of them.

Experimental Modal Analysis of Stator Overhangs of a Large Turbogenerator

Modal analysis of engg. structure for comprehending/resolving the vibration related issues/problems are well known. Two classical techniques-analytical (Finite Element Method-FEM) and experimental (Impact testing/Natural Frequency Test-NFT/Bump test) are generally used as complementary as well as stand-alone depending on the time, nature of structure, availability of the analysis tools, cost etc. In the present study, experimental technique was used in mitigating the endwinding vibration problem of a turbogenerator. In one of the Turbogenerators of 50 Hz variant, an increasing vibration trend was observed with system frequency sweep in almost whole of the endwinding basket particularly more on exciter end during sustained short / open circuit conditional runs. Experimental modal analysis was carried out of the overhangs. Frequency response functions (FRFs) were generated in local and global modes. The analysis thereon indicated global resonance of stator overhangs. Accordingly, appropriate remedial measures were planned and implemented. Consequently, global resonance frequency was shifted to higher zone, which in turn, resulted into substantial reduction in endwinding vibration levels.

INVESTIGATION OF SIMULATION EXPERIMENT ON ACTIVE CONTROL OF TORSIONAL VIBRATION IN A TURBOGENERATOR SHAFT SYSTEM

According to the theoretical analysis and calculation on the base ofcontinuous mass system, the simulation experimental investigation on active control of torsionalvibration in a turbogenerator shaft system is conducted. A test installation with the excitation ofgenerator motor and multi-stepped shaft system is established to simulate the torsional vibration ofa turbogenerator rotor shaft system, and to examine the active control strategy presented. Someuseful results are reached in the experimental study.

OPTIMUM CONTROL TO A PARTIALLY CONTROLLED TURBOGENERATOR SHAFT TORSIONAL VIBRATION SYSTEM

The optimal control to a partially controlled turbogenerator shaft torsionalvibration system is investigated. The principle of input feedforward control is presented to achievethe minimum of the average vibration energy in a system, and the optimal control matrix of thesystem is derived. A turbogenerator shaft system is taken as an example to simulate the optimalcontrol process of the torsional vibration. Results from this simulation indicate that the vibrationcan be effectively controlled by a partial control strategy.

Simulating the operation action of an asynchronized turbogenerator under loss of excitation

The control strategy for asynchronized turbogenerators (ASTGs) was studied by using two-axis equations. Simulation of the process of an asynchronized turbogenerator with faults of d or q axis or d and q axes in the excitation system was carried out with the simulating models including the model of the reverse thyristors in the excitation system established by Saber software. The simulation results show that at the loss of excitation at both windings or one winding of the rotor, the ASTGs can be automatically driven into an asynchronous or single axis excitation operation mode without a power unit tripping, and the characteristics for ASTGs with faults in the excitation system appear in good order.

Brushless Excitation System with Microcomputerbased Regulator for Turbogenerators

A new brushless excitation system with the modified microcomputer-based regulator developed by NARI was put into operation recently on a 300 MW #4 generator, Hanchuan plant, Hubei province. The hardware and software implementation of the regulator is briefly described in the paper. The onsite smooth operation of the generator with this excitation system proves that the system is quite

A Proof of Lyapunov Stability of a Nonlinear Observer for the Mechanical States of Turbogenerator Systems

The dynamics of a turbogenerator are characterized by a nonlinearly interacting electrical and mechanical subsystems. Accurate and robust state reconstruction by an observer should be based on its nonlinear dynamic behavior. Linear and reduced order observers are undesired since intolerable error of state reconstruction may be expected especially if the operating conditions and/or the external disturbances are, as usual in modern power systems, extremely changed. The 2nd authors of this paper had published a methodical design of a full order nonlinear observer for turbogenerator systems and conducted its experimental validation on a 120 MVA and 1,000 MVA synchronous generators at Gud-Power Station in south Munich （Germany） and the Nuclear Power Station of Goesgen （Switzerland）. In this paper, the Lyapunov＇s stability is applied to the mechanical slow motion of nonlinear observer. A second order Lyapunov function is introduced. Based on the energy interpretations of its terms, the necessary and sufficient conditions for the asymptotic stability of this nonlinear observer are derived.

核电半速汽轮发电机励磁绕组匝间短路时转子涡流损耗研究

为研究核电半速汽轮发电机励磁绕组匝间短路时转子涡流损耗特性,推导了核电半速汽轮发电机空载运行时励磁绕组匝间短路故障下,定子分数次谐波环流产生的合成磁动势表达式,分析合成磁动势相对于转子的转速,揭示了转子表面产生涡流的原因以及涡流的频率特性。结合涡流损耗计算方法,以一台核电半速汽轮发电机为例进行了仿真验证。在此基础上,对核电半速汽轮发电机励磁绕组不同位置发生相同程度匝间短路,以及励磁绕组发生不同程度匝间短路过程进行了仿真,计算了转子各阻尼条及槽楔中的涡流及涡流损耗,揭示了励磁绕组匝间短路时影响转子阻尼条及槽楔中涡流和涡流损耗的因素。为核电半速汽轮发电机励磁绕组匝间短路故障时,分析转子发热的影响因素提供了理论基础。

汽轮发电机带有交替径向风道的转子流体与传热耦合分析

针对汽轮发电机带有交替径向通风道的转子发热冷却问题,以一台350 MW水氢氢冷汽轮发电机为研究对象,依据流体力学和传热学的基本理论,首先建立计及旋转的电机全域通风网络模型,采用逐次迭代法计算得到各支路流量和节点压力。其次,建立了带有交替径向风道的发电机转子流体-传热三维物理模型和数学模型,给出了基本假设和相应的边界条件,同时将通风网络计算得到的风速和压力作为转子求解域的耦合边界,采用有限体积法进行求解,计算结果与实测值吻合。然后分析了交替径向风道内流量分配和氢气流动情况,研究了转子内部氢气温度分布和槽楔出风口风温变化规律,探明了转子绕组和铁心轴向温度分布特性,讨论了副槽入口流量和槽楔出口直径对转子流体和温度的影响。得出副槽入口流量应控制在0.1~0.16 m^(3)/s范围内,且选择较小的槽楔出口直径,可以提高通风系统的效率与风量分配均匀性,降低转子轴向热不平衡。

向心透平发电膨胀机静压气体轴承设计与承载特性分析

为提升有机朗肯循环(organic Rankine cycle,ORC)系统向心透平发电膨胀机静压气体轴承的承载力与刚度,采用表压比法设计了以R245fa为润滑工质的静压气体轴承,分析转子偏心率、供气孔尺寸、进气压力对静压气体轴承承载力与刚度的影响。实验结果表明:在相同供气压力下,轴承承载力与刚度随着转速的增大而增大;在相同转速下,0.7 MPa供气压力相对于其他气体供气压力轴承的承载力与刚度略高;静压气体轴承的偏心率越大承载力越大;相同供气孔直径下,静压气体轴承的承载力与刚度随着转速的升高而升高;随供气孔直径增大,静压气体轴承的承载力和刚度也随之增大。

1000MW汽轮发电机组轴系多跨零试重动平衡技术应用分析

随着我国电力装备制造水平及高速平衡技术的快速发展,近年来新投产的大型汽轮发电机组振动故障率呈现快速下降趋势。受实验条件限制,以三大动力为代表的制造厂商在汽轮发电机组转子出厂前只对单转子进行动平衡,而汽轮发电机组的轴系实际工作状态为多转子刚性连接,多支撑同步承担的多转子高速旋转轴系。受支撑刚度和连接刚度的影响,部分转子的原动态响应特性发生变化,加之残余不平衡响应的耦合,导致若干机组在试运期间相继发生轴系多跨振动超标故障。以一台1000MW汽轮发电机组多跨轴系振动故障处理为例,从轴系布置形式、振动机理、平衡策略等方面进行论述,归纳提出多跨零试重动平衡技术,为类似故障的诊断与分析提供参考。

百万千瓦二次再热汽轮发电机刚性框架基础动力性能研究

1 000 MW超超临界二次再热机组在降低能耗、减少污染方面具有显著优势,近年来,这类机组投运量增长显著。汽轮发电机作为电厂的关键核心动力装备,其基础结构振动控制是保障电厂安全可靠运行的重要环节。二次再热机组汽轮发电机轴系长、转子重,为降低振动影响确保机组平稳安全运行,以往1 000 MW超超临界二次再热机组汽轮发电机基础普遍采用弹簧隔振基础。该研究围绕1 000 MW超超临界二次再热机组汽轮发电机刚性框架基础的动力性能开展数值分析和模型试验研究,结果表明:1 000 MW超超临界二次再热机组汽轮发电机刚性框架基础具有良好的动力性能,正常运转阶段各扰力点振动线位移响应幅值不大于20μm,满足我国标准限值要求。研究成果可为1 000 MW超超临界二次再热机组汽轮发电机基础结构选型和设计提供技术支撑。

超超临界汽轮发电机轴系动力学研究及应用

针对汽轮机热效率亟待提高的问题,通过对超超临界汽轮机轴系的临界转速、不平衡响应和稳定性特点的研究,发现其结果满足API684的要求。机组在168 h调动全部资源运作期间,轴振最大值小于76μm,振动稳定可靠。

大型汽轮发电机端盖漏氢原因分析与预防

本文通过研究氢冷发电机日常维护中存在的漏氢缺陷,制作专用堵漏装置并带压完成堵漏,及时消除运行中外部漏氢隐患,机组停运后重新装配端盖并更换密封瓦,消除了内漏的缺陷。对漏氢原因进行分析总结,提出防范此类故障的措施,对发电机日常维护及检修管理等进行梳理,制定科学的维护制度,提升发电机大、小修的检修质量。

一种内外定子结构的多风区汽轮发电机外机座卧式配装挡风板工艺应用

本文介绍了一种多风区内外定子结构的汽轮发电机卧式配装挡风板工艺方法及应用。此工艺方法解决了立式配装挡风板一直存在占用关键厂房的紧张吊车资源、T型平台资源、作业高度高、效率低等问题,对于并行作业提高生产效率有积极作用。本文在定子外机座卧式配装挡风板的专用工具设计,测量中心柱的挠度计算,现场实配应用等方面进行分析阐述。

基于径向基函数神经网络算法的汽轮发电机转子绕组匝间短路故障诊断

转子绕组匝间短路是汽轮发电机的主要故障之一,对该故障的既有诊断方法仍有不足。在分析径向基函数神经网络基础上,提出一种基于该神经网络的汽轮发电机转子绕组匝间短路故障诊断方法。详细介绍了该方法的故障诊断流程,并对其进行了仿真验证。研究表明,该方法精度高且收敛速度快,可有效诊断汽轮发电机转子绕组匝间短路故障。

汽轮发电机转子绕组短路故障在线定位方法研究

针对汽轮发电机转子绕组短路故障,首先进行了故障电磁特性分析,短路故障发生后励磁磁动势中出现了偶数次故障特征谐波。为进一步考虑短路位置、磁饱和、发电机工况及电机齿槽等因素的影响,建立有限元模型,对多种故障情况进行模拟,获得了不同故障情况下的气隙径向磁密变化,谐波分析结果表明,气隙径向磁密变化各次谐波含量与相位和故障槽位置有关。气隙径向磁密的偶数次谐波分量会在定子并联支路中引起环流,而且并联支路环流各次谐波含量与相位和故障槽位置有关,据此借助定子并联支路环流谐波幅值与相位信息提出了一种非侵入式故障检测与定位方法,可对转子任意槽短路故障进行在线检测与精确定位,从而为汽轮发电机的长期安全稳定运行提供保障。

一种汽轮发电机汽端锥面双键槽对称度的检测设备

介绍了一种汽轮发电机汽端锥面双键槽对称度的检测设备,阐述了该检测设备的结构及使用方法,并进行了计算分析和误差分析。该检测设备的设计为汽轮发电机汽端锥面双键槽对称度的检测提供了一种结构合理、精确度高、通用性高的设备。