水轮发电机组结构振动及基础承载力计算分析

灯泡贯流式水轮发电机组一般采用卧轴结构,通过对大轴可能存在的载荷工况进行了全面的分析,得出了影响卧式轴系的主要运行工况,为设计和安装提供了技术支持。     

基于直接负载法的某水轮发电机温升试验分析

鉴于定子及转子的温升指标是水轮发电机的重要运行参数之一,采用直接负荷法对某80 MW水轮发电机进行了温升试验,因当前试验水头低机组达不到额定负荷,计算并校正了当前最大负荷工况下发电机的定子绕阻、定子铁心及转子绕阻的温升情况,并对额定负荷工况下的各部温升进行了推算,计算和推算值均满足设计要求。该研究为水轮发电机安全运行提供了技术数据。     

灯泡贯流式水轮发电机组稳定性测试与分析

对某电站灯泡贯流式水轮发电机组的运行状态进行了全面的综合性能测试,依据相关的技术标准进行了评价,划分了机组振动区域,对机组存在的问题提出了改进措施,为机组检修、运行提供了科学依据。     

国内最大贯流式机组投产发电

中国水利水电集团承建的全国最大的灯泡贯流式机组-广西桥巩水电站首台机组顺利投产发电,标志我国在超大型灯泡贯流式水轮发电机机组的设计、制造、安装领域达到了世界一流水平。     

带有直流输电系统的大型水轮发电机组的正负励磁系统稳态分析

介绍了正负励磁系统；建立了大型水轮发电机组的带地方负荷接线方式下的稳态模型及高压直流输电系统（ＨＶＤＣ）的准稳态（ＱＳＳ）等值阻抗模型、正负励磁系统的派克模型以及发电机对长线充电的线路模型；分析了正负励磁系统对空载长线充电距离的影响和带有直流输电系统对发电机吸收无功能力和发电机运行的静态稳定性的影响。仿真结果表明，大型水轮发电机组装有正负励磁系统，并采用直流输电系统向远距离输电具有很大的经济效益。     

株溪口水电站水轮机结构的设计特点

株溪口水电站装有4台18.5 MW灯泡贯流式水轮发电机组,均采用安德里茨公司的三叶片转轮。本文介绍了该电站灯泡贯流式水轮机转轮及其它各部件的设计过程和结构特点,以供同行参考。     

大型水轮发电机温度场与热应力分析

近年来水轮发电机的单机发电容量愈来愈大,水轮发电机的电磁负荷和热负荷也随之增加,研究大型水轮发电机的电磁分析、温度与热应力尤为重要。以某大型水轮发电机组为例,采用ANSYS-Rmxprt组件建立某大型水轮发电机的等效模型,再通过ANSYS的Maxwell2D仿真模块对水轮发电机电磁有限元模型进行瞬态电磁场分析,分别求解水轮发电机定子系统在空载和额定负载两种工况下产生的铜耗及铁耗。然后建立水轮发电机定子系统三维结构模型并导入电磁损耗密度进行电磁稳态温度场耦合分析,求解水轮发电机定子系统在空载和额定负载工况下的温度分布。最后将温度场分析与结构热力学分析耦合,求解水轮发电机热应力分布,为降低大型水轮发电机工作温升和预防结构热应力变形提供理论依据。     

株溪口水电站水轮机结构的设计特点

株溪口水电站装有4台18．5NW灯泡贯流式水轮发电机组，均采用安德里茨公司的三叶片转轮。本文介绍了该电站灯泡贯流式水轮机转轮及其它各部件的设计过程和结构特点，以供同行参考。     

灯泡贯流式水轮发电机定子铁心松动的原因及改造分析

针对某水电厂两台灯泡贯流式水轮发电机相继出现的定子铁心松动的问题,从电磁设计和结构设计方面对导致定子铁心变形、松动的原因进行了详细分析,并在此基础上进行了发电机改造分析。     

三峡电源电站机组发电机转子绝缘降低故障及其处理

针对三峡电源电站水轮发电机组在初期运行中频频出现发电机转子绝缘降低的故障,分析了电源电站机组发电机转子绝缘降低的原因,介绍了技术改进的措施,总结了处理机组发电机转子绝缘降低故障的经验.     

Evaluation of the effects of rotor harmonics in a doubly-fed induction generator with harmonic induced speed ripple

This paper is concerned with the low-frequency harmonics which originate from the rotor inverter of a doubly-fed induction generator (DFIG). By including the mechanical speed response, it expands the transformer approach previously taken to analyze the harmonic transfer in the machine. A numerical method is proposed to calculate the stator current sidebands, which can be used to predict the voltage fluctuation at the system busbar. It is shown that the pulsating torque associated with the rotor harmonics can induce speed ripple depending on the inertia, causing a significant change in the stator current spectrum. Experiment and simulation verify the analysis and the proposed calculation method.     

风力发电机组的自适应转矩控制及载荷优化

针对变速变桨风力发电机组(variable speed variable pitch,VSVP)如何在低风速时最大限度捕获风能以及在额定风速以上降低传动链载荷进行研究。低风速时在研究了传统风能追踪控制策略的基础上,文中提出通过改变最优增益系数来追踪最佳风能利用系数的自适应转矩控制策略。同时针对风力发电机组传动链的扭转振动,提出了基于发电机转速反馈滤波的转矩纹波控制方式。以2MW变速变桨风力发电机组为验证对象,基于Blade软件平台对所采用的控制策略进行仿真研究。结果表明：所提出的自适应转矩控制策略能够更好的追踪最大功率点,同时采用转矩纹波能够降低传动链载荷     

DFIG-DVR系统在不平衡电网电压下的运行特性

针对双馈风电机组(DFIG)在电网电压不平衡时,二倍频扰动分量会造成定转子过电流、功率脉动、转矩脉动等一系列电气和机械的问题,提出了新型DFIG-DVR系统,即串联DVR始终维持DFIG定子端电压恒定,从根源上隔离电网不平衡故障的影响,从而在整个故障运行过程中,DFIG仍可以实现转子侧变换器功率解耦控制和网侧变换器维持直流电压恒定的目标。采用PSCAD/EMTDC建立DFIG-DVR系统模型,对比分析了电网电压不平衡时DVR的不投切与投切对DFIG的影响。结果表明,在电网电压不平衡条件下,所提控制方案可以实现DFIG的平衡运行。     

CFD simulation of a floating offshore wind turbine system using a variable-speed generator-torque controller

Prediction and control of rotor rotational velocity is critical for accurate aerodynamic loading and generator power predictions. A variable-speed generator-torque controller is combined with the two-phase CFD solver CFDShip-Iowa V4.5. The developed code is utilized in simulations of the 5 MW floating offshore wind turbine (FOWT) conceptualized by the National Renewable Energy Laboratory (NREL) for the Offshore Code Comparison Collaboration (OC3). Fixed platform simulations are first performed to determine baseline rotor velocity and developed torque. A prescribed platform motion simulation is completed to identify effects of platform motion on rotor torque. The OC3’s load case 5.1, with regular wave and steady wind excitation, is performed and results are compared to NREL’s OC3 results. The developed code is shown to functionally control generator speed and torque but requires controller calibration for maximum power extraction. Generator speed variance is observed to be a function of unsteady stream-wise platform motions. The increased mooring forces of the present model are shown to keep the turbine in a more favorable variable-speed control region. Lower overall platform velocity magnitudes and less rotor torque are predicted corresponding to lower rotor rotational velocities and a reduction in generated power. Potential improvements and modifications to the present method are considered.     

双馈感应风力发电系统低电压穿越控制

传统的双馈感应发电机(DFIG)矢量控制方案忽略了定子暂态磁通,导致当电网出现故障时控制性能恶化.为了提高电网故障下DFIG的不间断运行能力,将矢量控制与自抗扰控制器结合起来,利用扩张状态观测器估计出定子暂态磁通和电机参数误差对系统的影响并加以补偿.仿真结果表明该文提出的控制方法削弱了电网故障时DFIG的转子暂态电流峰值和电磁转矩波动,有效地保护了转子变频器和风力机机械结构,而且对电机参数误差具有鲁棒性.     

Neuber法则在汽轮机转子寿命估算中的应用

高温大容量汽轮机在启动、停机以及负荷波动时对机组的使用寿命有很大影响。正确分析机组在多种工况下转子的应力水平和寿命损耗是当前大型机组保证安全运行及加强寿命管理中亟待解决的关键问题之一。为此,应用Neuber法则对600MW超临界机组转子进行了寿命损耗计算。计算结果表明冷态启动对转子的寿命损耗最大。     

Torsional torque suppression of generator based on H∞ control theory in isolated power system

Renewable energy power plants, such as wind turbine generator and photovoltaic system, have been introduced in isolated power system recently. The output power fluctuations of wind turbine generator and load deviations result in frequency deviation and terminal voltage fluctuation. Furthermore, these power fluctuations also affect the turbine shafting of diesel generators and gas‐turbine generators, which are the main components of power generation systems in isolated islands. For stable operation of gas‐turbine generator, the torsional torque suppression as well as power system stabilization should be considered. In this paper, the control strategy that achieves torsional torque suppression and power system stabilization is presented based on H_∞ control theory. The effectiveness of the proposed control system is validated by numerical simulation results. Copyright © 2010 John Wiley & Sons, Ltd.     

Compensation of network voltage unbalance using doubly fed induction generator-based wind farms

A control strategy for compensating AC network voltage unbalance using doubly fed induction generator (DFIG)-based wind farms is presented. A complete DFIG dynamic model containing both the rotor and grid side converters is used to accurately describe the average and ripple components of active/reactive power, electromagnetic torque and DC bus voltage, under unbalanced conditions. The principle of using DFIG systems to compensate grid voltage unbalance by injecting negative sequence current into the AC system is described. The injected negative sequence current can be provided by either the grid side or the rotor side converters. Various methods for coordinating these two converters are discussed and their respective impacts on power and torque oscillations are described. The validity of the proposed control strategy is demonstrated by simulations on a 30 MW DFIG-based wind farm using Matlab/Simulink during 2 and 4% voltage unbalances. The proposed compensation strategy can not only ensure reliable operation of the wind generators by restricting torque, DC link voltage and power oscillations, but also enable DFIG-based wind farms to contribute to rebalancing the connected network.     

分数阶PID混合算法的水轮机调速系统优化控制与建模分析

为深入研究水轮机调速系统的非线性动态特征,分析水轮机在负荷波动时调速系统对水轮机转速、出力及输出电压电流波形的控制情况,提出一种采用混合算法(BP-FOA)的分数阶PID(FOPID)双目标函数控制系统;并利用Matlab平台建立了能够反映动态负荷变化及发电机情况的水轮机模型,使其更具实际适应性。仿真及实例分析表明,经混合算法优化后的水轮机调速器在调节性能与鲁棒性上均有一定的提升,同时亦为水轮机动态模型建模提供了借鉴。     

Modeling,control, and simulation of dual rotor wind turbine generator system

A new wind turbine generator system (WTGS) is introduced, and its mathematical model, blade pitch control scheme, and nonlinear simulation software for the performance prediction are presented. The notable feature of WTGS is that it consists of two rotor systems positioned horizontally at upwind and downwind locations, and a generator installed vertically inside the tower. In this paper, this new WTGS is treated as a constrained multi-body system, and the equations of motion are obtained by using the multi-body dynamics approach. Aerodynamic forces and torques generated from each of rotor blades are calculated using the blade element theory. Various pitch control schemes depending on the wind speed and the main rotor's rotational speed are implemented. A relatively simple model for the load torque is obtained by using the test data of the doubly fed induction generator adopted in the new WTGS. Finally, FORTRAN and Matlab/Simulink-based hybrid simulation software is developed and used to predict and analyze the performance of the WTGS.