抽凝式汽轮机组故障原因分析与处理

抽凝式汽轮机组在运行中若发生主油泵断油,则由主油泵产生的润滑油和调节油将瞬间失压,引起机组跳机。机组在热态起动过程中若抽汽口有低压蒸汽或水导入将会使汽轮机中间汽封急冷收缩,致使汽轮机转子与中间汽封发生碰擦,引起机组振动升高而跳机。就上述2种故障发生的原因做了分析,并提出了针对性的改进措施。     

浅析核电汽轮机润滑油中气泡的特征及影响

核电汽轮机的润滑油系统会不可避免地漏入空气并形成气泡,这影响了油系统的可靠运行。对核电汽轮机润滑油中气泡的产生现象及负面影响做了简要介绍,并结合润滑油的特性及油中气泡的运动和受力分析,说明了温度、压力及油箱结构等因素对润滑油析气的影响,最后对油系统及设备设计方案提出了优化建议。研究成果可为核电汽轮机润滑油系统的设计优化提供参考。     

射油器数学模型的建立及仿真

建立了射油器的数学模型,对600MW机组射油器进行了仿真研究,为汽轮机润滑油系统的仿真及故障诊断建立了基础。     

核电汽轮机润滑油油箱滤网设计及结构优化

核电汽轮机润滑油对机组运行安全起着至关重要的作用,其清洁度对轴承润滑性能有直接的影响。阐述了核电汽轮机润滑油的主油箱滤网设计特点,根据现有核电项目油系统现场冲洗、反复用油对滤网的冲击情况,对主油箱滤网进行了相关结构优化研究,保证了后续机组滤网的耐久安全,从而保证机组轴承用油的可靠性。研究成果可为同类型机组的润滑油滤网设计提供参考。     

给水泵汽轮机油中带水原因分析及处理

福建华电可门电厂Ⅰ期工程2×600MW超临界燃煤机组1#机组于2006-08-03日投产发电,2#机组于2006-12-04投产发电。给水泵汽轮机油站的润滑油自2006年双投以来,经常出现油中带水的现象,这种现状不但造成凝结水的大量损失,而且影响到了机组的安全稳定运行,深入分析了机组运行及设备深层次的原因并给出了设备改造的具体解决方案和改造后的运行效果。经过现场技术分析及改进,有效地避免了给水泵汽轮机油站油中带水的现象,保证了给水泵及给水泵汽轮机的安全、经济运行。     

AP1000核电汽轮机润滑油系统调试

润滑油系统是汽轮发电机机组的重要组成部分,对机组的安全稳定运行至关重要。阐述了AP1000核电汽轮机润滑油系统的冲洗、调试工作,重点对调试过程中出现的问题及调试中好的做法进行了经验反馈,并对后续机组调试、运行提出了优化建议和注意事项,为同类机组润滑油系统调试提供了参考。     

汽轮机组断油烧瓦典型案例分析

汽轮机润滑油系统是保证汽轮机安全运行的重要系统,润滑油系统故障会造成断油烧瓦事故。断油烧瓦不是新课题,但判明断油烧瓦原因很重要,这涉及制定更合理的监管和预防措施。文章简述了印尼某电厂1号汽轮机停机过程中交流润滑油泵因线路故障停泵,同时润滑油系统未能切换至直流润滑油泵供油所引起的断油烧瓦事故。通过对事故经过的调查,分析了交、直流润滑油泵未正常联锁的原因,找出预防润滑油断油事故的措施。     

210MW汽轮机中的润滑油含水量超标的治理

对汽轮机润滑油微水含量超标的原因进行了分析,介绍了机组运行中采取的调整控制措施,提出了设备检修方面应采取的改进措施。目的是防止因汽轮机润滑油微水含量超标而引发事故。     

S109FA燃气机组直流油泵自动启动失败的处理方法

S109FA燃气机组正常运行时由380 V交流润滑油泵提供轴系润滑油和发电机氢气密封油;2台交流润滑油泵都故障时,直流润滑油泵自动启动代替交流润滑油泵工作;当发电机氢气密封油压力低于设定值时直流密封油泵自动启动,使发电机氢气密封油的油压力维持在合格的范围之内。本文介绍了直流润滑油泵和直流密封油泵在自动启动失败的紧急情况下的处理方法,为S109FA燃气机组和其它型号的燃气机组处理类似的故障提供参考。     

大功率汽轮机组润滑油系统的可靠性

本文以法国阿尔斯通(Alsthom)公司大功率汽轮机组先进的润滑油系统为例,通过国产机组曾发生过的润滑油系统事故,分析了提高大功率汽轮机可靠性的途径:如润滑油系统与调节油系统分离;采用直吸直供式主油泵、无阀系统、无误操作切换系统和半容量辅助油泵;建立一轴承一泵的独立顶轴油系统及应用全封闭直接作用式油温调节器等.图4     

背压机组循环水系统的改造

热电联产企业大多选择背压机组和抽凝机组组合的方式,以同时满足热、电负荷的需要。循环水泵参数一般按抽凝机组的容量设计,背压机和抽凝机共用一套循环水系统。当背压机组单独运行时,循环水泵出力就远大于机组需用水量,造成厂用电的浪费。这时通过对循环水系统的改造,由小泵为背压机组提供冷却水,可有效降低厂用电量。     

风电场中多台风力机的数值模拟

将NREL 5 MW风力机作为基本机型,使用致动线模型和大涡模拟相结合的数值方法,在中性大气边界层中模拟含有多台风力机的风电场。为了模拟风电场的复杂入流条件,首先模拟体积为3000 m(长)×3000 m(宽)×1000m(高)的大气边界层,并对模拟结果进行验证,结果表明:在覆盖逆温层以下,不同高度处的位温不变,平均风速满足剪切特性,脉动风速满足湍流谱特性;然后,分析了致动线模型中风轮直径上的网格节点数量(N)和高斯分布因子(ε)的取值规律,发现ε以网格尺度(η)为自变量取值时,N越大,η的系数越大,当N取63时,η的系数可取2或3,但N取25时,η只能取1.2;最后,使用致动线模型在大气边界层中布置8台风力机,模拟风电场,并对风力机间的相互干扰进行分析,发现第一排风力机功率明显大于其他风力机功率输出,占风场总功率输出的40.3%。     

Investigating the possibility of using different hub height wind turbines in a wind farm

Many researchers have focused on the layout design of a wind farm using the computational methods. Most of previous researches focused on relevant large cell size and using same hub height wind turbines. In this paper, the authors investigate the possibility of using different hub height wind turbines in a wind farm. A limited area (2?km?×?2?km) with constant wind speed and direction is considered as the potential wind farm area, and a nested genetic algorithm is used as optimisation algorithm. Two different hub height wind turbines are introduced with two different cell sizes. Power output, cost, payback period, and total profit are selected as evaluation criteria when comparing the layouts with same hub height wind turbines with the layouts with different hub height wind turbines. The results demonstrate that it is feasible and possible to use different hub height wind turbines in a wind farm.     

基于CFD的二维垂直轴风力机性能计算

采用计算流体力学方法(CFD)针对垂直轴风力发电机,开展简化的二维绕流特性研究。首先,基于开放型转子和增强型转子,研究网格节点数和壁面y+、计算时间步长和湍流模型等的变化对计算结果的影响,对计算模型和方法进行确认。随后,计算分析增强型垂直轴风力机与开放型垂直轴风力机的特性。结果表明,与开放性垂直轴风力发电机相比,增强型垂直轴风力发电机的功率系数和转矩系数有明显增加,且达到最大值的位置向叶尖速比增大的方向移动。然后对增强型垂直轴风力机发电机在不同来流风速下进行计算,发现增强型垂直轴风力发电机的转子转矩随来流风速增加,而转矩系数和功率系数与来流风速无关。最后,针对定子叶片在不同的方向开展计算研究。结果表明,定子叶片在不同方向时,增强型垂直轴风力机的转子转矩不同,且转矩到达峰值的位置也不同;在当前3个方向角中,叶片处于0°方向角时风力机具有最高的转矩系数,即具有最佳的功率系数。     

Large‐eddy simulations with extremum‐seeking control for individual wind turbine power optimization

Large‐eddy simulations of the flow past an array of three aligned turbines have been performed. The study is focused on below rated (Region 2) wind speeds. The turbines are controlled through the generator torque gain, as usually done in Region 2. Two operating strategies are considered: (i) preset individual optimum torque gain based on a model for the power coefficient (baseline case) and (ii) real‐time optimization of torque gain for maximizing each individual turbine power capture during operation. The real‐time optimization is carried out through a model‐free approach, namely, extremum‐seeking control. It is shown that ESC is capable of increasing the power production of the array by 6.5% relative to the baseline case. The extremum‐seeking control reduces the torque gain of the downstream turbines, thus increasing the angular speed of the blades. This results in improved aerodynamics near the tip of the blade that is the portion contributing mostly to the torque and power. In addition, an increase in angular speed leads to a larger entrainment in the wake, which also contributes to provide additional available power downstream. It is also shown that the tip speed ratio may not be a reliable performance indicator when the turbines are in waked conditions. This may be a concern when using optimal parameter settings, determined from isolated turbine models, in applications with waked turbines. Copyright © 2017 John Wiley & Sons, Ltd.     

Fundamentals applicable to the utilisation of marine current turbines for energy production

The potential of electric power generation from marine tidal currents is enormous. Tidal currents are being recognised as a resource to be exploited for the sustainable generation of electrical power. The high load factors resulting from the fluid properties and the predictable resource characteristics make marine currents particularly attractive for power generation and advantageous when compared to other renewables. There is a paucity of information regarding various key aspects of system design encountered in this new area of research. Virtually no work has been done to determine the characteristics of turbines running in water for kinetic energy conversion even though relevant work has been carried out on ship’s propellers, wind turbines and on hydro turbines. None of these three well established areas of technology completely overlap with this new field so that gaps remain in the state of knowledge. This paper reviews the fundamental issues that are likely to play a major role in implementation of MCT systems. It also highlights research areas to be encountered in this new area. The paper reports issues such as the harsh marine environment, the phenomenon of cavitation, and the high stresses encountered by such structures are likely to play a major role on the work currently being undertaken in this field.     

Rapid optimization of stall‐regulated wind turbine blades using a frequency‐domain method: Part 2, cost function selection and results

A fast and effective frequency‐domain optimization method was developed for stall‐regulated blades. It was found that when using linearized dynamics, typical cost functions employing damage‐equivalent root bending moments are not suitable for stall‐regulated wind turbines: when the cost function is minimized, the edgewise damping can be low, and the flapwise damping can approach zero during an extreme operating gust. A new cost function is proposed that leads to nicely balanced stall behavior and damping over the entire operating windspeed range. The method was used to design the blades of two multi‐MW, stall‐regulated, offshore wind turbines, comparable with the NREL 5 MW and NTNU 10 MW pitch‐regulated turbines. It is shown that the optimal stall‐regulated blade has a unique aerodynamic profile that gives high flapwise and edgewise damping and a uniform mean power output above the rated windspeed. The blades are described in sufficient detail that they can be used in further aeroelastic analyses, to compare large stall‐regulated and pitch‐regulated turbines. Copyright © 2014 John Wiley & Sons, Ltd.     

考虑动态失速与风轮支架损失的H型垂直轴风力机自由尾迹模型构建

采用基于升力线理论的自由尾迹模拟模型,耦合了Leishman-Beddoes（LB）动态失速模型和模拟支架损失的半经验公式,编制H型垂直轴风轮计算程序,对不同直径、不同实度的风轮进行气动性能模拟。为了检测模型对H型风轮输出计算的准确性,选取2种不同实度（分别为0.13和0.48）的H型风力机进行了对比分析。结果表明,当尖速比小于4时,动态失速影响较为明显。考虑支架损失的计算结果明显优于未考虑支架损失的计算结果,支架损失总体上随尖速比的增大而增大,2台风力机对应的最大支架损失分别高达60%和35.5%。考虑动态失速效应和支架损失的计算模型能较为准确地估算风轮实度较小的H型风轮的输出,但对于实度较大的H型风轮,其计算准确度有待进一步提高。     

Research on a power quality monitoring technique for individual wind turbines

The extensive deployment of megawatt-scale wind turbines is bringing more challenges to the safety and stability of electric grid than ever before. This is not only because of the unstable wind over time but the increased risk of power quality pollution by defective wind turbines particularly when the turbines today are still experiencing various reliability issues. To prevent the power quality pollution by defective turbines, a new power quality monitoring technique dedicated for individual wind turbines is developed in this paper, so that the quality of the power generated by an individual turbine can be monitored by the wind turbine condition monitoring system. Through simulated and physical experiments on a specially designed test rig, some encouraging results have been achieved. It has been shown that the proposed technique is not only valid for monitoring the power quality of an individual wind turbine, but helpful in detecting the mechanical and electrical faults occurring in the wind turbines.     

Exploring the benefits of vertically staggered wind farms: Understanding the power generation mechanisms of turbines operating at different scales

Wind farms are known to modulate large scale structures in and around the wake regions of the turbines. The potential benefits of placing small hub height, small rotor turbines in between the large turbines in a wind farm to take advantage of such modulated large‐scale eddies are explored using large eddy simulation (LES). The study has been carried out in an infinite wind farm framework invoking an asymptotic limit, and the wind turbines are modeled using an actuator line model. The vertically staggered wind turbine arrangements that are studied in the present work consist of rows of large wind turbines, with rows of smaller wind turbines (ie, smaller rotor size and shorter hub height) placed in between the rows of large turbines. The influence of the hub height of the small turbines, in particular, how it affects the interactions between the large and small turbines and consequently their power, along with the multiscale dynamics involved, has been assessed in the current study. It was found that, in the multiscale layouts, the small turbines at lower hub heights operate more efficiently than their homogeneous single‐scale counterparts. In contrast, the small turbines with higher hub heights incur a loss of power compared with the corresponding single‐scale arrangements.