The damping effect of the flywheel dampers installed at different shaft couplings on torsional oscillations

This paper eamines the damping effect of flywheel dampers installed at different shaft couplings on torsional oscillations on the 951 MW turbine-generator shafts due to network faults. A studied system is described and torsional fatigue on the turbine shafts following various electrical system disturbances is analyzed and evaluated. Moreover, the influence of the safety factor selected and set at the design stage to the shaft life expenditure due to fatigue damage is also presented. Useful additional insight into their modes of operation is obtained from the fast Fourier transform of the transient response results. All computer simulations thus show that the proposed dampers are effective in suppressing the torsional oscillations on the shafts. In this paper, time-domain torque evaluation is also combined with the fast Fourier transform method to derive a selection procedure for obtaining suitable flywheel dampers to depress the amplitude of these critical shaft oscillations to acceptable levels.     

考虑整机转矩控制的双馈风机轴系扭振机理分析及抑制策略

双馈风电机组轴系模型可等效为风力机质块经柔性轴与发电机质块连接,其轴系柔性较大,阻尼较低,现场存在轴系扭振现象.提出将整机转矩控制嵌入双馈风机两质量块数学模型中,并进行小信号线性化,得到适用于轴系动态特性分析的双馈风电机组机电小信号模型,基于该模型开展扭振机理分析和抑制策略设计.双馈风机轴系扭振本质原因是电磁转矩与发电...     

A New Damper Scheme to Restrict Torsional Torques on the Turbine Generator Shafts and Blades near a HVDC Link

Due to more various power disturbances occurring in a power system involving a HVDC link, the turbine generator shafts and/or blades are more prone to damage than in general HVAC systems. In this paper, a new mechanical damper scheme based on participation factor approach is proposed to damp torsional torque and prolong the life of turbine mechanism. Two types of torsional damping couplings, inertia damping coupling and elastic damping coupling, are adopted and examined. The optimal type and the optimal location of the damping coupling will be identified and installed to the turbine generator shaft section. The results demonstrate that the best damper may not be installed at the location with the most onerous vibrations but provides satisfactory damping performance on shafts and blades following severe power disturbances in a HVDC link.     

双馈风电机组传动系统扭振抑制自抗扰控制

扭振是造成风电机组传动系统零部件疲劳损伤的主要原因之一。为了通过控制减小风电机组传动系统疲劳载荷,本文在分析风电机组传动系统中非线性不确定因素作用的基础上,设计了一种扭振抑制自抗扰控制器。该控制器将传动系统中的非线性不确定因素作用和外界扰动归结为系统总扰动,通过扩张状态观测器进行实时估计,并在发电机转矩控制中给予补偿,增强了控制器的适应性和鲁棒性。以3MW双馈风电机组为控制对象的试验结果表明,该控制器可以在不影响机组发电量的前提下抑制传动系统扭振,明显减小齿轮箱的转矩波动,从而减轻扭转载荷对主要零部件的疲劳损伤。     

QFSN600MW汽轮发电机组轴系对电网大扰动和机组滑极承受能力的研究

研究电网大扰动对ＱＦＳＮ６００ＭＷ汽轮发电机组轴系扭振疲劳寿命损耗的影响,详细研究了机组滑极时的动态行为和机电耦合轴系扭振现象,提出了滑极运行的限制判据。     

TORQUES IN MULTI-MACHINE GENERATOR SHAFTS DUE TO HVOC RECTIFIER RIPPLE CURRENTS SUPERIMPOSED ON THE DC CURRENT IN ASYNCHRONOUS LINKS

ABSTRACT

This paper analyses torsional vibrations in steam turbine-generator-exciter shafts of machines in multi-machine power systems in close proximity to the inverter station due to rectifier ripple currents superimposed on the DC current in asynchronous DC links. It extends earlier work to include an in-depth analysis of system scaling factors for modulation product harmonic currents impressed on generators not examined in the literature heretofore by an inverter in an asynchronous link.

Frequency at which shaft torsional vibrations would be excited by modulation product harmonics in 50Hz/50Hz asynchronous links as a function of deviation in system frequency is first reviewed. Amplitude of shaft torque due to steady resonant torque excitation which is a function of initial rate of increase of vibration at adjacent cells where the steady resonant torque excitation is applied, the time constant for decay of the vibration and stiffness between adjacent cells is then discussed. The paper then shows that torque in shafts of machines in multi-machine networks may be estimated by proportioning HVDC Link inverter modulation product harmonic disturbance current appropriately to each machine at risk. A three phase fault studies programme to proportion converter harmonic current to each machine is discussed. System scaling factors are evaluated for different scenarios : (i) neglecting system loads, (ii) using a lumped load at the inverter, and (iii) employing distributed system loads for (a) constant impedance loads and (b) subtransient reactance dynamic loads. The effect of tappings of transformers is also discussed. On the basis of these evaluations, generators are identified which are most at risk. Torques in shafts of the machines in Ireland due to rectifier ripple currents superimposed on the DC current of the proposed North Wales/Ireland Link are then analysed and discussed.     

电网扰动对外高桥发电厂300MW汽轮发电机组轴系疲劳寿命的影响

介绍外高桥电厂３００ＭＷ汽轮发电机组在电网扰动下轴系的疲劳寿命损耗的评估情况。     

电网短路故障下双馈风电机组传动链扭振响应

电网故障引起的电磁转矩波动易造成风电机组轴系扭振疲劳损耗,严重时会造成轴系故障,有必要研究不同类型电网故障下风电机组传动链扭振响应及其对关键部件的影响。首先,采用集中质量法,考虑叶片柔性建立了风电机组传动链四质量块模型,基于小信号模型,采用模态分析法对风电机组传动链扭振特性进行分析。其次,为了表征不同故障类型对风电机组传动链轴系扭振的影响,在双馈发电机电磁暂态模型的基础上,推导了电网对称与不对称故障下电磁转矩表达式。最后,基于四质量块传动链模型,仿真分析了单相、两相和三相接地电网故障对机组传动链扭振响应的影响。结果表明,不同类型电网故障会影响不同传动链扭振频率及其不同关键部件;三相接地电网故障引起的传动链扭振幅值大,齿轮箱和发电机转子间轴上传递转矩可以较全面反映扭振响应频率;与传动链其他部件相比,发电机转子受到电网故障影响更大。     

汽轮发电机组轴系扭振分析

本文用三质量模型分析汽轮发电机组轴系扭转振动问题,建立机组轴系扭转振动的分析模型。以研究机组轴系在发电机、励磁机的激振扭矩作用下的扭转振动特性为例,得到了模型的幅频特性曲线和响应的表达式。同时还得到了短路冲击作用下,轴系的扭转角响应和各轴段(联轴器)上扭矩响应的解析解。     

大型汽轮发电机失步振荡的网机耦合仿真

在研究分析了大量有关资料,特别是一些国际组织的研究成果,结合各系统、各制造厂的实践经验,对1039MW汽轮发电机组失步振荡进行了网机耦合仿真,对不同电网故障造成的发电机、轴系和电网的冲击大小进行计算,并评估其造成的轴系疲劳寿命损失。研究结果表明：机组在失步振荡20个周期,发电机绕组端部振动、绕组发热、轴系疲劳寿命损耗均在许可范围内,机组承受失步振荡的能力完全满足标准和技术规范要求。     

国产600MW汽轮发电机组轴系异常振动分析与处理

某国产600MW超临界汽轮发电机组轴系在运行中经常出现异常振动。这不仅迫使系统多次临时停机．而且存在较大安全隐患。本文采用电涡流位移传感器对该机组7号轴瓦的异常振动进行监测,通过波德图和频谱分析发现,引起系统异常振动的主要原因是发电机转子及低压缸发电机对轮质量不平衡。经过处理,7号轴瓦振动水平明显降低,系统轴系振动恢复到正常范围。     

并网双馈感应风电系统轴系振荡特性

在风速突变及电网短路故障等外界扰动下,并网双馈感应发电机(DFIG)风电系统将表现出传动轴系的振荡,由此引起输出功率的振荡,这将可能导致与该风电系统强耦合的电力网络产生低频振荡,降低DFIG风电系统本身及其所并电网的安全稳定运行能力。针对DFIG风电系统轴系振荡的阻尼特性,采用电磁阻尼转矩分析方法,对常用控制模式下DFIG电磁转矩对轴系阻尼的作用机理进行推导,以此为基础,详细分析风速、发电机参数以及系统控制参数对该作用行为的影响规律,为系统振荡阻尼控制器的设计及其优化奠定理论基础。最后,利用DIg SILENT/Power Factory仿真平台建模并进行了相关仿真证明。     

基于多传感器信息融合技术的汽轮发电机轴系扭振刚性转速的估计

基于分布式多转速传感器测量信号的冗余性和互补性,利用多传感器信息融合技术提出1种估计刚性转速、实现扭振滤波的方法。基于模态分析理论提出1种刚性转速的融合规则,由1个极小极大问题确定最优的加权因子。通过对传感器故障的检测与分离,提高信息融合方法估计刚性转速的精度和容错能力。对1台实际机组和扭振试验的在线监测数据滤波处理的实践表明,多传感器信息融合刚性转速的滤波方法性能良好且易于实现,是1种解决扭振与汽轮发电机控制系统相互作用问题的有效措施。     

变速变桨风力发电机组塔架的侧向振动控制

针对结构阻尼很小的大型兆瓦级变速变桨(Variable Speed and Variable Pitch,VSVP)风力发电机组如何抑制塔架的侧向振动问题进行研究,提出在控制器的设计中,借助反馈增益并使用塔顶振动加速度测量值来确定附加的电机转矩设定点,并在反馈控制回路中使用椭圆带通滤波器和切比雪夫低通滤波器,进而改善塔架侧向振动阻尼。以某5 MW变速变桨风力发电机组为验证对象,基于Bladed软件平台对该控制策略进行仿真验证。结果表明:所提出的控制策略能够有效降低塔架的侧向振动位移,且对叶轮转速和电机扭矩没有太大影响。     

发电厂次同步振荡(SSO)问题的解决方法

当直流换流站发生单极或双极闭锁时,靠近直流换流站的发电机组就极有可能产生次同步振荡(SSO),这就迫切需要引入发电机轴系扭振保护(TSR)装置和SEDC装置来用于解决次同步振荡(SSO)引发的轴系扭振,避免造成轴系某些部件如联轴器断裂或疲劳损坏,保证机组和电网的安全运行。     

大型半速核电发电机转子轴系的扭振疲劳损耗

利用电力系统机网相互作用数字仿真程序MANDISP,专门对某大型核电半速机组发电机转子轴系扭振疲劳特性展开研究,计算大机组的轴系扭振频率、典型电网扰动冲击情况下的扭应力以及扭振疲劳寿命损耗等重要技术参数。并将其与现有行业标准进行对比分析,用于指导该发电机组轴系设计。     

大扰动下次同步谐振仿真分析的模型改进及应用

结合实际工程需求及实践经验,对次同步谐振(sub synchronous resonance,SSR)仿真研究几个重要方面,即机组轴系、串补及附加励磁阻尼控制(supplementary excitation damping control,SEDC)建模和RTDS仿真进行了精细化研究,使其适用于大扰动时的SSR模式稳定性、暂态扭矩和疲劳损耗的精确分析。将改进仿真方法应用于实际串补输电工程,通过上都电厂送出系统一次短路故障情况下SSR事件的仿真分析,并与实际结果进行对比,验证了所述方法在实际工程SSR分析中的适用性、准确性和有效性。SSR仿真与实际大扰动事件对比分析在国内外应属首次,具有重要的参考价值。     

CURRENT AND TORQUE STRESSES IN SYNCHRONOUS MACHINES DUE TO SEQUENTIAL OUT-OF-PHASE SYNCHRONIZING

ABSTRACT

The effects of non-simultaneous closing of breaker poles during out-of-phase synchronizing on the stator current, electrical and shaft mechanical torques of a turboset are investigated and compared with the current and torque peaks following simultaneous three-phase and single-phase out-of-phase synchronizing. It has turned out that in comparison with the three-phase out-of-phase synchronizing considerable increase in the current and torque peak values can occur following an unfavourable sequential closing.     

固态限流器抑制轴系扭振的研究

电力系统故障会引起汽轮发电机组轴系的扭振,本文分析了在发生三相接地和单相接地故障情况下,固态限流器对提高发电机暂态稳定性和轴系扭振的影响.通过Matlab仿真计算电磁转矩、汽轮机轴系扭振和机端电压的变化,仿真结果表明固态限流器除了具有良好的限流功能外还能够提高电机暂态稳定性和抑制轴系扭振.     

汽轮发电机组轴瓦自激振动故障分析及处理

某50 MW汽轮发电机组检修后在运行过程中出现异常振动现象,发电机转子振动突增.分析振动突增的原因为发电机转子发生了轴瓦自激振动.经现场检查分析,轴瓦自激振动的诱因为发电机转子轴承座标高偏小、轴瓦顶隙偏大、润滑油品质较差和轴瓦磨损.通过调整轴承座标高、轴瓦顶隙、轴瓦侧隙、改善润滑油品质和处理轴瓦磨损,解决了轴瓦自激振动...