【作者】 徐亮；

【导师】 袁景淇；

【作者基本信息】 上海交通大学 ， 控制科学与工程， 2016， 博士

【摘要】 火力发电,尤其是燃煤机组发电是我国电力工业的主体。但是,由于所涉学科领域多、机理复杂、测点不完备以及固有的时变、非线性、大时滞、多变量、多干扰等特性,燃煤机组在工艺、运行、控制优化等方面还有大量问题有待解决。随着我国经济发展带来的环境污染影响日益凸显,对燃煤机组的运行优化、性能评估、控制优化的需求也越来越迫切。本文涉及燃煤机组全流程机理建模以及基于模型的若干关键变量在线监测、运行优化、控制优化问题。本文的主要研究成果包括:(1)改进了工质物性参数的计算公式IAPWS-IF97在临界区的计算方法,提出迭代法与工质状态判定相结合的方法,解决了直接采用温度、压力迭代计算密度时的多解问题。(2)提出了基于氧量在线测量和煤质离线分析的烟气成分实时估计方法,以及适用于温度范围273.15~2000 K、压力范围0~200 kPa的基于烟气成分实时估计的烟气物性参数计算方法。(3)建立了燃煤机组全流程机理模型。对于锅炉侧,建立了制粉系统、蒸发系统、换热器系统、金属壁能量动态蓄积、热损失的集总或准分布参数的机理模型;对于汽机侧,建立了汽轮机系统、回热抽汽系统、冷端系统机理模型。(4)研究了基于锅炉侧机理模型的入炉煤低位发热量的在线辨识方法,并从72小时、一月两个时间尺度上,分别采用原始化验值与剔除化验误差后的校正化验值对实时辨识的低位发热量进行验证,结果表明所提在线辨识方法具有较高的精度和较强的实用性。进而,提出了基于入炉煤低位发热量在线辨识的燃料主控优化方案,并对锅炉侧能效进行了实时评估。(5)研究了在线确定并滚动更新机组煤耗特性的方法。提出了四种调度模式下的最优化问题,并通过实例验证了四种调度模式下,根据机组煤耗特性合理分配机组负荷,可以达到明显的节能降耗效果。(6)研究了汽轮机系统的白箱与黑箱模型,利用二者的等效性,推导出了低压缸排汽湿度的在线监测方法。研究了通用于单背压、双背压凝汽器冷端系统的最优化问题,提出了冷端优化计算流程,结果表明冷端系统具有明显的潜在优化空间。最后对汽机侧能效进行了实时评估。(7)基于适当简化的全流程机理模型,建立了锅炉-汽轮机四阶、二输入、二输出的多变量非线性状态空间模型,并结合真实机组数据进行了参数辨识与模型验证。提出了基于反馈线性化的FL-PID、FL-SMC协调控制策略,并对比研究了常规PID、FL-PID、FL-SMC的控制特性。更多还原

【Abstract】 In the foreseeable future,thermal power plant,especially the coal-fired units,will remain the dominant in the electrical industry in China.However,due to the complex mechanism,the incomplete measurements,and the inherent features of the coal-fired unit such as time-varying,nonlinear,great time constant and lag time,multiple variables,much interference,etc.,there are a lot of pressing problems to be investigated in the process,operation,and control optimization.Under the ever increasing pressure on environment protection,the demand for the operation and control optimization becomes more and more urgent.In this study,the modeling of the whole process mechanism and the key issues in the operation and control optimization for the coal-fired power plant are investigated.The major innovative achievements are as follows:(1)The calculation formula of thermodynamic properties of the water and steam in Region 3 of the IAPWS-IF97 is improved.Combining the iteration and the state criterion law,the possible multi-solution problem of the direct iteration is avoided.(2)The online composition estimation method of the flue gas is proposed based on the online oxygen content measurement and the offline ultimate analysis of the coal.Then,a generic calculation method of the thermodynamic properties of flue gas based on the online composition estimation is presented with the validity range as 273.15 ~2000 K and 0~200 kPa.(3)The whole process mechanism model of the coal-fired unit is established.The lumped or quasi-distributed parameter mechanism models in the boiler-side include the pulverizing system,evaporation system,heat exchanger system,metal wall energy compensation,and heat loss.The mechanism models in the turbine-side include the steam turbine system,regenerative extraction system,and cold end system.(4)The online identification approach of the lower heating value of the coal entering the furnace is presented based on the boiler-side mechanism model.Then,the online identified lower heating value is validated using the original and rectified(got rid of the assay error)assay value in the time scales of 72 hours and one month,respectively.The results show the proposed approach has high accuracy.Based on the online identified lower heating value,an improved fuel master control strategy is proposed.Also,the online efficiency assessment for the boiler-side system is carried out.(5)An online determination and rolling update approach of coal consumption characteristic is presented.Then,the unit load dispatch in four different modes is researched based on the online coal consumption characteristic.The validation shows that the reasonable load dispatch can achieve significant coal saving benefit.(6)The white and black box models of the steam turbine system are developed.Based on their equivalence,an online identification approach of the exhaust steam wetness fraction of the low pressure cylinder is developed.On the basis of that,a generic calculation procedure of the cold end optimization problem is researched for both of the single and double back-pressure condensers.The simulation result proves that the cold end system has potential optimization space.Then,the online efficiency assessment for the turbine-side system is also performed.(7)Based on the simplified whole process mechanism model,a fourth-order nonlinear state space model of the boiler-turbine system with two inputs and two outputs is established,whose parameters are identified and validated with the history data from a real 300 MW coal-fired unit.Then,the coordinated control strategies based on feedback linearization,i.e.FL-PID and FL-SMC,are presented.Finally,the simulation results based on the three control strategies,i.e.PID,FL-PID,and FL-SMC,are compared.更多还原