大型汽轮发电机组轴系静特性分析方法研究

大型汽轮发电机组轴系的安装参数直接关系到机组的安全稳定运行,因此需合理设计轴系的安装扬度曲线以确定各轴承标高及载荷等静特性参数,并在安装过程中予以保证。基于三弯矩方程和传递矩阵法,建立了轴系安装扬度曲线的数学计算模型,给出了一种设计计算轴系静特性的方法,并编制了计算程序。以国内某百万千瓦等级汽轮发电机组单支撑轴系为研究对象,在给定边界条件下进行了静特性分析,计算结果与有限元分析反推结果对比,验证了该方法的准确性,为指导大型机组轴系的安装提供技术参考。     

国产300,600MW汽轮机组轴系扭振研究的新思路

对国产３００,６００ＭＷ汽轮机组轴系扭振研究的发展,提出如下一些见解;轴系基本方程中阻尼系数Ｄ不可忽略,须对轴系疲劳寿命评估方法进行修正,应开展对机组低压缸末级叶片振荡应力的设计计算。     

国产300、600MW汽轮机组轴系扭振研究的新思路

对国产300、600MW汽轮机组轴系扭振研究的发展,提出如下一些见解:轴系基本方程中阻尼系数D不可忽略,须对轴系疲劳寿命评估方法进行修正,应开展对机组低压缸末级叶片振荡应力的设计计算。     

大型轧钢机的扭振问题

本文讨论大型轧机轴系的扭振问题。文中叙述轧机轴系扭振分析,简化了计算模型,将间隙引起的非线性问题线性化,并在此基础上讨论了跳闸、双锭连轧等工况下的扭振问题,从振动机理出发,建立了振动方程和初始条件,提出了这些工况下的扭振计算方法。     

汽轮发电机组的扭振计算

本文介绍了用霍尔兹法对汽轮发电机组轴系扭转固有频率和振型进行计算的过程。同时还介绍了计算轴系对瞬态电磁转扭的响应的方法。     

水轮机阶梯式口环水封的转子动力特性系数的计算

本文首先在Ｈｉｒｓ紊流润滑理论的基础上,采用体积流动模型及Ｍｏｏｄｙ摩擦方程建立起阶梯口环水封中流体流动的控制方程,将各个方程在转子与定子同心处进行摄动,采用Ｒｕｎｇｅ－Ｋｕｔａ积分法及迭代过程求解摄动方程,建立起水轮机阶梯式口环水封的转子动力特性系数的计算方法,为水轮发电机组轴系的动力学分析提供了必要的理论基础。     

动态同步轴系及其应用

在综述参考系理论的发展与应用的基础上,提出了一种用于对称电机动态过程分析的新轴系———动态同步轴系,建立了该轴系下的励磁控制方程,并在该轴系下仿真研究了异步化水轮发电机稳态有功、无功及转速调节特性,仿真结果证明了该轴系的有效性。     

多轴系汽轮发电机组中心调整过程分析

多转子的轴系中心调整是一项复杂的工作。实际检修过程中,要经过多次计算,多次试验,并进行优化才能调整到位。针对此情况,引进了由实缸到半缸再到实缸的调整方案,以图表形式编制了汽轮发电机组轴系调整的快速计算方法。并以N335-16.18/538/538汽轮发电机组的轴系大修中心调整过程为例,探讨有关轴系中心计算调整标准的制定,调整计算方法及调整过程中应注意的事项。最后介绍了D600A型汽轮机联轴器螺栓紧固的工艺流程及矢量图法,以期为同类机组的检修调整提供参考。     

基于ANSYS的汽轮发电机组轴系扭振模态分析

汽轮发电机组轴系扭振固有特性分析通常假设轴系材料力学性能参数为常数,而在实际运行过程中机组沿轴系轴向其温度是变化的,轴系材料力学性能参数也会相应地发生变化,从而导致固有特性发生变化,影响轴系扭振响应的计算精度.分析了轴系的模化方法,并通过有限元分析软件ANSYS建立了轴系的有限元模型.针对满负荷工况下的轴系温度分布规律...     

汽轮发电机组轴系不平衡响应 计算的影响系数法

将目前发电机组轴系质量不平衡响应计算方法和柔性转子现场动平衡方法相结合, 在给出转子一阶、二阶质量不平衡模型基础上, 提出了计算轴系不平衡响应的影响系数法。这一方法可以用于汽轮发电机组轴系振动特性设计计算;所计算的响应值对于现场机组轴系平衡时计算加重量有参考价值     

A method for analysis of back-swing phenomena of synchronous machine in multimachine power systems

This paper describes a new approach to the analysis of the back-swing phenomena in multimachine power systems. When a short-circuit fault occurs in a power system, some generators decelerate in a short period immediately after the fault in some cases. The phenomenon called back swing is caused by the transient responses in armature winding of synchronous machines and in transmission lines. To represent the back swing in detail by a mathematical model, these transient behaviors have to be described by sets of differential equations. Then not only does the order of differential equations increase, but the convenient expression of the transmission system by a set of node equations becomes useless. In this paper an equivalent power system model for the simple representation of the back swing has been proposed. First, an impedance for each machine that represents the transient of transmission system has been introduced. It is assembled into the differential equations associated with armature winding response. Then the transmission system is represented by a constant impedance matrix. This model makes it possible to calculate the transient behavior of armature flux in multimachine power systems. The transient torque brought to the rotor shaft by the flux is calculated directly and it represents the back-swing phenomena effectively.     

Adaptive robust boundary control of shaft vibrations under perturbations with unknown upper bounds

This paper presents robust and adaptive boundary control designs to stabilize the two‐dimensional vibration of hybrid shaft model. The hybrid shaft is mathematically represented by a set of partial differential equations, governing the shaft vibrations, coupled to ordinary differential equations, describing rigid body spinning and dynamic boundary conditions. The control objective is to stabilize the transverse vibrations of the perturbed shaft while regulating the spinning rate. To achieve this, the paper first establishes robust boundary control laws that fulfil the control objective in the presence of modeling uncertainties and external disturbances operating over the shaft domain and boundary. Lyapunov‐based analyses show that the proposed robust control exponentially stabilizes the shaft with vanishing distributive perturbations, while assuring ultimately bounded vibrations in the case of nonvanishing perturbations. Then, adaptive control philosophy is utilized to achieve redesigned robust controllers that only use online adaptation of control gains without acquiring the knowledge of bounds on perturbations, as well as dynamic parameters. An advantage of this design is avoiding an overconservative robust control law, which may induce poor stability and chattering in tackling system perturbations with unknown upper bounds. Simulations through finite element method illustrate the results. Copyright © 2014 John Wiley & Sons, Ltd.     

利用发电机空载特性曲线的不平衡磁拉力分析方法

不平衡磁拉力是影响水轮发电机组轴系动力特性最重要的因素之一。为了更准确地分析轴系动力特性,本文提出一种利用发电机空载特性曲线计算不平衡磁拉力的分析方法。利用发电机空载特性曲线,通过磁路计算及多项式拟合获取气隙磁密、气隙厚度及励磁电流的关系方程,计算考虑了励磁电流及饱和效应影响的不平衡磁拉力。以葛洲坝水轮发电机为实例,分析在考虑饱和效应时,不平衡磁拉力随定转子偏心及励磁电流的变化规律。通过与已有不平衡磁拉力分析方法的对比,验证了该方法的有效性。     

A low-order system frequency response model

The authors present the derivation of a simple, low-order system frequency response (SFR) model that can be used for estimating the frequency behavior of a large power system, or islanded portion thereof, in response to sudden load disturbances. The SFR model is a simplification of other models used for this purpose, but it is believed to include the essential system dynamics. The SFR model is based on neglecting nonlinearities and all but the largest time constants in the equations of the generating units of the power system, with the added assumption that the generation is dominated by reheat steam turbine generators. This means that the generating unit inertia and reheat time constants predominate over the system average frequency response. Moreover, since only two time constants predominate, the resulting system response can be computed in closed form, thereby providing a simple, but fairly accurate, method of estimating the essential characteristics of the system frequency response     

计算轴系扭振固有特性的Riccati法

本文将Riccati传递矩阵法推广到轴系扭振固有特性的计算,理论分析和数值计算表明,这种方法具有编制程序简单、占有内存少、运算速度快、数值稳定和计算精度高等特点。因此这是一种较为理想的计算轴系扭振固有特性的方法。     

Efficient computation of frequency response of digital networks

A major requirement in the analysis of multi-input-multi-output digital networks is to compute the frequency response at a large number of points from a knowledge of the graph of a network with specified input and output nodes. Though the usual method of analysis by solving linear equations is more efficient than matrix inversion, solution of linear equations at each frequency may still require a large amount of computation. A more efficient method is to determine the poles and zeros of the desired system function and then calculate the frequency response from them. Though poles of the system function could be readily identified as contained in the eigenvalues of the state matrix of the network, difficulty is seen to arise in the determination of zeros which can not so easily be calculated. A simple and efficient method is proposed reducing the determination of zeros to a standard eigenvalue problem.     

水电机组轴系统实测振动分析及动态参数识别

对某实际水电站机组及其支承结构实测振动数据分析基础上,针对大型水电站机组连续运行,无法施加有效激振,油膜只在机组运行时存在等特点,基于多信号分类法,将模态参数时域识别引入到水电站机组轴系统的自振特性研究中;同时针对传统油膜动态特性参数识别方法的不足,提出了可以不受测点少,工况少等实际情况限制的遗传识别方法,对机组导轴承油膜动态特性参数进行了识别,为机组轴系统自振特性及振动响应的研究提供了基础。根据油膜动态特性识别结果进行了轴系统自振特性的有限元数值反馈计算,验证了两种识别方法及结果的正确性。     

Electromagnetic and resistance torque on a synchronous motor shaft with permanent magnet excitation

This paper considers methods for indentifying electromagnetic and resistance torque on a permanent magnet synchronous motor shaft with rotor-position feedback in steady-state and dynamic modes under sine-wave voltage applied to motor windings. The authors give relatively simple equations for an electromagnetic-torque observer.     

核电TA1100-78型半速发电机轴电流检测系统在线测试与诊断分析

针对CPR1000 TA1100-78型半速发电机轴电流检测装置,提出了一种在功率平台下在线进行系统有效性测试的方法,该方法简单实用,可全面校验检测回路与监测装置本体的正确性,提高轴电流监测系统在机组起动后的可靠性。同时结合现场实践经验,对该机型轴电流出现后的异常诊断流程进行了分析,为同类型机组类似问题的处理提供参考。     

Numerical solution of inhomogeneous and non-linear ordinary differential equations using the TLM multicompartment model

The paper presents a simple algorithm for solving a system of inhomogeneous high order differential equations with variable coefficients. The method also provides a numerical solution to non-linear ordinary differential equations. The technique is based on reducing the high order equations into a system of first order rate equations. Through a simple translation process, the variables in the reduced set of equations are solved simultaneously by an iterative scheme using the TLM multicompartment model. The numerical technique is demonstrated by solving well-known second order differential equations. The numerical solutions are compared with the analytical solutions to the differential equations.