【作者】 秦志明；

【导师】 刘吉臻；

【作者基本信息】 华北电力大学 ， 热能工程， 2014， 博士

【摘要】 随着电力需求的不断增长,大容量、高参数、高自动化技术的超超临界机组已经成为我国主要建设的火电机组。火电单元机组是一类具有典型非线性特征的多变量被控对象,它具有大迟延、大惯性、强耦合以及参数的时变性等特点。并且随着电力工业可持续发展战略的实施,电网综合自动化对单元机组协调控制系统的性能提出了更高的要求。建立单元机组模型并深入研究其动态特性是协调控制系统优化的工作基础。本文研究了超超临界直流炉的动态建模以及将线性自抗扰控制引入火电机组协调控制系统的解耦控制。论文的研究内容包括以下几个方面。提出一种基于稀疏化核偏最小二乘法的软测量方法。在不同状态下的水和水蒸气的热力性质差异很大,特别是在临界区表现出很强的非线性。基于一定范围内水和水蒸气的本质特性,通过该方法对工质的热力状态参数进行软测量,并将其应用于直流锅炉的机理建模。建立直流锅炉蒸发受热面和过热器的动态模型,通过仿真实验和运行数据分析得到模型中各参数随负荷变化的规律。根据水和水蒸气的热力性质,确定划分汽水区域的标准,通过求解锅炉蒸发受热面物性代数方程、动量和能量微分方程,得到工质参数沿受热面流程的数值解。金属的蓄热占超超临界直流锅炉的蓄热的主要部分,将锅炉金属蓄热表达式转化为随中间点焓值和主汽压力变化简便的计算式。利用风量氧量构造的热量信号对制粉系统的惯性系数和迟延时间进行闭环辨识。研究超超临界机组各个组成部分的特点,依据基本物质平衡和能量平衡关系建立各个部分机理模型,通过合理简化,获得具有解析形式的模型表达式。通过仿真实验和机组运行数据的对比分析,验证了模型的准确性。提出一种基于线性自抗扰控制器的超超临界单元机组三输入三输出协调控制系统。得到了典型热工对象的基于降阶观测器的线性自抗扰控制系统的等效控制结构形式,根据改进的D-分割法,确定出控制参数域。在控制器与机组对象间设计了全解耦补偿器,可实现锅炉侧与汽机侧、燃料侧与给水侧的解耦,保证系统的全局控制品质,仿真研究验证了该方法的有效性。更多还原

【Abstract】 With the increasing demand for electricity in China, Ultra supercritical units which have large capacity, high parameters and advance automation currently accounted for the major part in thermal power construction. The thermal power unit is a kind of multivariable nonlinear plant with large time delay, large inertia, strong coupling, time-varying parameters characteristics. With the implementation of the strategy of sustainable development in power industry, the power grid integrated automation system has put forward higher requirements to coordinated control system (CCS) of power unit. Therefore, building the power unit non-linear model and further research of its dynamic characteristics are the basis of coordinated control system optimization. This paper studies the dynamics modeling of ultra-supercritical once-through boiler, and linear ADRC will be introduced to decoupling control for thermal power unit coordinated control system.The main contribution of this dissertation are summarized as follows:According to the properties of water and steam within limits, Sparse kernel partial least squares (SKPLS) method was used for soft measurement of the thermal properties of the working medium in relevant subcooling, evaporating and superheating section. Under different working conditions the thermodynamic properties of water and steam varies greatly, especially in the region3of IAPWS-IF97, which shows strong nonlinearity. The method was applied to mechanism modeling of the once-through boiler.The heat storage of boiler and the coal-pulverizing system’s inertia coefficient and time-delay were important affecting factors for boiler load instruction variation rate. The momentum and energy differential equations were coupled with the algebraic equations of properties of water and steam, approaches for solutions of the coupled algebraic and differential equations were presented, water and steam parameters profiles along it’s journey were settled out. According to the boundary equations of IAPWS-IF97, the evaporating heating surface was divided into3sections,such as subcooling, evaporating and superheating section. The model of the evaporating heating surface and the superheater was built through the mechanism analysis, the calculation result shows that metal heat storage accounts for the main part of ultra supercritical boiler. The metal heat storage was substitute for the boilers’ in the simplified model, the released heat was calculated by knowing the amount air and oxygen concerned, which was used to identified the inertia coefficient and delay time of coal-pulverizing system in closed loop.Studying the characteristic of various components of ultra-supercritical unit, according to the mass and energy balance to build up the mechanistic model,using the operating parameters in the vicinity of their units to simplify and fitting the model, and to obtain the analytic model of the form of expression. Through simulation experiments and comparative analysis of plant running data to verify the accuracy of the model.Research on linear ADRC for the typical thermal process--first order plus dead-time, the linear ADRC equivalent control system is presented, and analysis the Stability of the closed-loop system in the linear feedback control, the stability region of the controller parameters were determined on the basis of the improved D-partition approach. For MIMO nonlinear unit coordinated control system, the linear ADRC was introduced for each decoupled subsystem closed-loop controller design, the method is applied for1000MW ultra-supercritical unit coordinated system, simulation results show that the proposed coordinated control system is effective.更多还原