【作者】 吴吕斌；

【导师】 周怀春；

【作者基本信息】 华中科技大学 ， 热能工程， 2009， 博士

【摘要】 大型火力发电厂锅炉主蒸汽温度控制是电厂热工自动控制系统的重要组成部分。由于主蒸汽温度大迟延、大惯性等特点，采用传统PID控制器的主蒸汽温度控制系统的品质难以满足电厂安全、经济运行的需要。尽管国内外多位专家、学者多方研究对其进行优化，但局限于以锅侧参数信号为反馈信息变参数PID控制器仍然解决不了大迟延的问题。通过锅炉燃烧可视化检测技术获取的反映实时炉膛燃烧总能量的辐射能信号，可以引入到主蒸汽温度控制回路中，提前调节减温水量，从而有效的控制主蒸汽温度，从根本上解决了大迟延问题。基于这一思想，本课题在两个电厂各一台300MW机组锅炉上装设了炉内燃烧三维可视化检测系统，获取炉膛燃烧实时的辐射能信号。通过现场变工况动态试验，探寻了辐射能信号的变化规律，揭示水冷壁、过热器等与辐射能之间的静态关系。在现场试验积累的大量数据基础上，利用Matlab工具箱对主蒸汽温度被控对象进行模型辨识以及数值仿真。动态仿真结果表明辐射能信号响应时间快、超调量小；传统的热量信号初调易超调且响应时间慢。因此，融合辐射能信号与传统的热量信号的主蒸汽温度控制策略将获得较好的控制效果。将快速反映的炉侧辐射能信号与稳定性的锅侧热量信号进行联合控制的新策略应用在两台300MW机组锅炉主蒸汽温度控制系统中，通过各项对比性现场试验证明，引入辐射能信号的锅炉主蒸汽温度控制系统的品质得到了较大的提高：对应相同的大负荷扰动下主蒸汽温度波动值由±10℃减少到±3℃，减温水流量波动值也大幅减少。更多还原

【Abstract】 The boiler main steam temperature control system in large-scale coal-fired power plant plays a key role in improving the economic efficiency and ensuring the safety of the unit operation. The main steam temperature can be seen as the controlled object of multicapacity distribution parameters, in which the over high temperature of flue gas is the main reason for overheating of the superheated steam. The dynamic test of steam temperature and the analysis on power plant operation show that the superheated steam temperature delays little under the flue gas disturbances, while delays great under the disturbances caused by the spray water quantity. This characteristic will make the control of the overheating steam delayed, and induce it difficult to maintain the main steam temperature steady in operation by using the usual regulate method. Many domestic and foreign researchers introduced the intelligent control technology into the control of the boiler steam temperature, including predict control technology, adaptive technology, fuzzy control technology, neural network technology, genetic algorithm and so on, with a view to resolve the problems encountered in PID control system. However, it is difficult to satisfy the main steam temperature control, whether the traditional PID control system or the control strategy blended with advanced intelligence technology. That’s because these systems still use the heat signal to reflect the variety of fuel into the boiler, since the heat signal essentially belongs to the boiler steam side parameters, the characteristics of the heat transfer resistance, delay and lag still restrict the respond speed of the heat signal.It can make the lag weak by detecting the furnace combustion situation and temperature distribution to adjust spray water quantity in advance, so as to control main steam temperature effectively. The technology to monitor burning temperature distribution by flame radiation image, can detect furnace temperature distribution in real-time. Import furnace side signal to the main steam temperature control circuit, then adjust spray water quantity in advance, so as to control the superheating steam temperature effectively. The subject adopts the solution based on visual furnace combustion 3D temperature pattern, to get real-time furnace combustion information and temperature distribution, so as to extract furnace combustion radiation energy signal. Based on dynamic test on variable work conditions, the relation between the radiation energy signal and unit’s main operating parameters is analyzed to explore the change regulation of radiation energy signal during the thermal process. Through studying the heat absorption capacity of each heat transfer surface, the change rule between the heat release in furnace and the heat absorbing by heat transfer surface, as well as the static relation between radiation energy and heat transfer both in furnace and flue are explored.Contraposing lag problem in the traditional PID control system of the main steam temperature, and combining with the result of variable work condition tests and the analysis of heat transfer law, the paper put forward a new control tragedy which combined with the steady heat signals of boiler and furnace side radiation energy signal with rapid response. Make the radiation energy signals plus steam flow correction circuit signals as the original leading steam temperature control signals, and to form the new leading control signals of main control circuit by multiplied with the heat signal. Under the guidance of the qualitative analysis conclusion, the model identification and numerical simulation are realized by Matlab toolbox about experimental data which is gathered under certain conditions. Furthermore, two different main steam temperature control strategies depending on whether the furnace radiation energy signals imported or not are analyzed and compared, and a preferable simulation control effect is acquired.The main steam temperature optimization and control strategy based on radiation energy signals by importing it to the main steam control circuit have been carried out. The main steam temperature adjustment quality, with in-situ expriments in two 300MW boiler, is improved and the change range is from±10°C to±3°C by adjusting their weights.更多还原