AGC状态下大型火电机组轴流引风机动特性分析

发布时间：2018-08-21 10:57

【摘要】：随着可再生能源的大力发展,电网调峰面临的挑战越来越大。大型火电机组参与电网调峰成为必然,其调峰负荷响应速度亦成为考核机组对负荷响应能力的重要指标。目前国内对于有偿调峰与无偿调峰划分方式的探讨,尚未有明确的衡量调峰补偿与设备损坏程度的比对准则。本文探讨火电机组锅炉轴流风机在调峰过程负荷快速变化时的振动特性。通过采集火电机组现场风机振动数据进行分析得出定性结论,风机振动特性随着机组负荷变化幅度、变化速度不同均表现出不同的幅值大小。后进行定量分析,建立风机转子部件模型,计算叶片在不同负荷变化情况下的动特性响应。分析包括风机叶片的模态分析、谐响应分析以及瞬态激励响应分析。模态分析以评估风机共振状态,谐响应分析绘制应力、变形频率响应曲线,瞬态激励响应探讨不同负荷变化速度、不同负荷变化幅度下风机叶片的振动参数区别。首先通过现场测量数据建立轴流风机模型与流道模型[1],后利用CFD软件Fluent进行风机流场数值模拟,简化计算出流体作用于风机主轴上的扭矩,作为计算流体诱导振动的载荷。探讨三种不同工况下(BMCR工况、TB工况、THA工况)风机的振动特性,并得出结论,机组负荷变化幅值大时,系统振动超调量大,衰减周期长,越难达到稳定状态；机组负荷变化速度快时,系统振动超调量大,衰减周期长,越难达到稳定状态。本文通过对比分析,证明了火电机组在参与AGC调峰时,对机组锅炉辅机轴流引风机的工作状态有一定的影响。调峰的深度与速度不同,风机叶片表现出的振动特性也不同。此结论提醒电厂工作人员在机组参与有偿调峰时也要关注辅机的工作状态,需对比参与电网调峰补偿与辅机损坏的利害关系,做出综合考虑。同时,本文也作为深入计算风机在快速负荷变化的情况下寿命计算的参考方向,也为后续的研究提供理论依据。
[Abstract]:With the development of renewable energy, the challenge of peak-shaving in power grid is increasing. It is inevitable for large thermal power units to participate in peak-shaving, and their peak load response speed is also an important index to assess the capacity of generating units to respond to load. At present, there is no clear criterion to measure the compensation for peak shaving and the degree of equipment damage in the discussion of the division between paid and unpaid peak-shaving. In this paper, the vibration characteristics of the axial flow fan of thermal power unit boiler are discussed when the load changes rapidly during the peaking process. By collecting the field fan vibration data of thermal power units, the qualitative conclusion is drawn that the vibration characteristics of fans show different amplitudes with the varying amplitude of unit load and varying speed. After quantitative analysis, the rotor component model of the fan is established, and the dynamic response of the blade under different load changes is calculated. The analysis includes modal analysis, harmonic response analysis and transient excitation response analysis of fan blade. Modal analysis is used to evaluate the resonance state of fan, harmonic response analysis is used to draw stress, deformation frequency response curve, and transient excitation response to discuss the difference of vibration parameters of fan blade under different load changing speed and different load change amplitude. Firstly, the axial fan model and the flow channel model are established through the field measurement data. Then the flow field of the fan is numerically simulated by CFD software Fluent, which simplifies the calculation of the torque acting on the main shaft of the fan as the load to calculate the fluid-induced vibration. The vibration characteristics of the fan under three different working conditions (BMCR / TB / tha) are discussed. It is concluded that the larger the load variation amplitude, the larger the vibration overshoot, the longer the attenuation period, the more difficult to reach the stable state. When the load of the unit changes rapidly, the vibration overshoot of the system is large and the attenuation period is long, so it is more difficult to reach the stable state. Through comparison and analysis, it is proved that thermal power unit has certain influence on the working state of axial flow induced fan of boiler auxiliary machine when participating in AGC peaking. The vibration characteristics of fan blade are different with the depth and speed of peak shaving. This conclusion reminds the power plant staff to pay attention to the working state of auxiliary machines when the units participate in the paid peak-shaving. It is necessary to make a comprehensive consideration by comparing the interests of participating in the peak-shaving compensation of power grid and the damage of auxiliary machines. At the same time, this paper also serves as the reference direction for further calculation of the life of fan under the condition of rapid load change, and also provides theoretical basis for further research.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM621

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