【作者】 刘鑫屏；

【导师】 刘吉臻；

【作者基本信息】 华北电力大学（北京） ， 动力工程及工程热物理， 2010， 博士

【摘要】 火力发电在今后较长时期内仍将是我国电力能源供给的主要方式。维持火电机组正常、高效运转对实现我国节能、减排的指标至关重要,而实施状态检测及控制优化是实现这一目标的有效手段。由于火电机组热力系统较为复杂,一些重要的状态信号无法测量或测量不准确,成为影响机组参数控制品质和安全经济运行的重要原因。针对研究对象的特点,灵活应用机理分析和数据分析相结合的方法,对火电单元机组的主要热力系统进行分析。构造得到了一些物理意义明确、非常具有实际应用价值、能够反映热力系统运行规律的状态信号。具体包括：(1)煤发热量信号。通过分析发电过程中物质、能量流动的平衡关系,利用汽轮机调节级后压力、汽轮机高调门计算开度、汽包压力和锅炉总给煤量构造出煤发热量信号。信号动态性能优良,非常适合在控制系统中应用。(2)锅炉热量信号。通过对锅炉大量运行数据进行分析,发现锅炉总风量、排烟氧量、炉膛压力信号与给煤量信号之间存在特定的相关关系,进一步结合机理分析解释了这种关系的成因和规律,以此为基础构造出锅炉热量信号。信号精度足够、动态性能优良。(3)汽包锅炉虚假水位估计信号。通过分析汽包锅炉汽水系统物质与能量的平衡关系,建立描述汽包水位信号的模型。能够以较好的动态性能反映实际水位的变化,特别是“虚假水位”现象。该估计信号能够应用于控制系统优化。同时,在针对以上问题开展研究的过程中,涉及具体热力系统对象内在运行规律方面和理论研究方法方面,也获得了一定的研究成果。具体包括：(1)建立正压中速磨直吹式制粉系统动态模型,分析了模型中主要参数的变化规律,并指出一次风量是影响制粉系统惯性和迟延的关键因素。(2)提出容积蓄热系数的概念,在此基础上进一步提出一种锅炉蓄热系数的计算方法。(3)建立燃料量-引风机入口压力对炉膛压力-炉膛温度的简化非线性动态模型,揭示了炉膛压力与炉膛平均温度之间内在的相互作用关系。(4)建立汽包锅炉燃料量-汽轮机高调门开度-给水流量对机组负荷-机前压力-汽包水位的三入三出多变量动态模型,模型以微分方程形式给出,所有静态、动态参数均具有明确的物理意义,较Astrom于2000年建立的以偏微分方程形式给出的模型更具实用价值。(5)建立汽轮机回热加热系统模型,解释了凝结水节流影响机组负荷的内在原因及规律。更多还原

【Abstract】 The thermal power will be a predominant way of electric energy supplies for years to come in China. Keeping the normal and efficient operation of thermal power units is important for realizing the indicators of energy saving and emission reducing. The state parameter detection and control optimization are the effective measures to achieve this goal. However, the thermodynamic systems in larger thermal power units are complicated, so some important state signals cannot be real-time measured or cannot be measured exactly, which is an important element affecting the control performance and safe and economic operation of units. According to the characteristics of research object, based on the flexible combination of mechanism analysis and data analysis, the main thermodynamic systems of units were researched. And some state signals, which were of explicit physical meaning, of practical application value and can reflect the real operation law of thermodynamic systems, were gained. The work can be presented as follows:1. The signal of coal heat value was constructed. Through analyzing the balanced relations of mass flow and energy flow in the process of electricity generation, using the pressure of the turbine first stage, calculation opening of governing valve, drum pressure and boiler feed coal flow, the signal of coal heat value was constructed. This signal has the advantages of finer dynamic performance and also has better practical value in control system engineering application.2. The boiler heat release signal was gained. Based on the analysis of the large amount of boiler operation data, the particular correlativity relation between boiler air flow, oxygen content in boiler flue gases and feed coal flow was discovered. And then, combining with the mechanism analysis, the cause and the law of this relation were explained, based on which, the boiler heat release signal was constructed. This signal has finer dynamic performance and enough accuracy for engineering application.3. The estimation signal for drum false water level was constructed. Through analyzing the balanced relations of mass flow and energy flow in boiler water-steam system, the model that can describe the real drum water level signal was constructed. This signal can reflect the change of real drum water level with finer dynamic performance, especially the false water level phenomenon. This signal can be applied in the control system optimization. Meanwhile, in the process of research on the above problems, some research achievements in terms of the inner operation law and theoretical study methods for thermodynamic system were gained. The main work can be presented as follows:(1) The dynamic model of positive pressure pulverizing system of medium speed mill direct firing was constructed. The change law of main parameters in the model was analyzed. And it is pointed out that the primary air rate is the key factor, which affects the inertia and delay of pulverizing system. (2) The concept of volume heat storage coefficient was presented, on the basis of which, a method for calculating the heat storage coefficient was brought forward. (3) The simplified non-linear dynamic model of furnace pressure, furnace temperature versus fuel flow and the entrance pressure of induced draft fan was constructed. And the inner interaction relation between furnace pressure and furnace average temperature was revealed. (4) The multivariable dynamic model with 3 inputs/3 outputs of drum boiler fuel, opening of governing valve and feed water flow versus unit load, throttle pressure and drum water level was constructed, which was gained in the form of differential equation. All the static parameters and dynamic parameters of this model have the explicit physical meaning. This model has more practical application value than the one of Astrom model, which was constructed in 2000 in the form of partial differential equation. (5) The model of turbine heat regenerative system was constructed, and the inner cause and law of how the condensate throttling affects units load was explained.更多还原