基于金属蓄热动态的直流炉控制模型研究

发布时间：2019-01-30 19:36

【摘要】：近年来新能源发电正在如火如荼的发展,但在我国电力生产结构中火电仍占据主导地位,而且我国的一次能源结构决定了我国的火电机组主要以煤炭作为燃料。随着环境保护和节能减排的要求越来越高,火电机组必然向大容量高参数发展,超临界乃至超超临界直流机组正越来越成为主流,所以必须对大容量直流机组进行更深入的研究。而建立适用于超超临界直流机组控制系统设计的模型是前提。为了达到以上目的,本文进行了如下工作：1.对超临界直流锅炉的蓄热进行分析。运用机理分析方法,得到了水冷壁中工质的比焓和压力随炉膛高度的分布,基于IAPWS一IF97分区标准,将水冷壁划分为过冷水段、过渡段和过热段；然后利用质量守恒定律和能量守恒定律推导出了直流锅炉水冷壁和过热器蓄热的计算式；最后引用谏壁电厂1000MW机组锅炉的设计参数对锅炉蓄热进行了计算,通过对数据的分析,得出结论：塔式直流锅炉的水冷壁蓄热与过热器蓄热大体相当,金属蓄热远大于工质蓄热,锅炉蓄热可以由金属蓄热近似代替。2.在结构上将直流锅炉机组划分为制粉系统、锅炉系统和汽轮机系统,针对三个系统分别运用机理分析法构造了模型,并将对于直流锅炉蓄热的数据引入锅炉系统建模过程,对模型进行了修正,构造了一个适用于超临界直流机组的通用模型结构；然后利用谏壁电厂#14号机运行的历史数据,用回归分析和遗传算法辨识,得到了机组模型的未知参数和待定函数,最终构造了一个三输入三输出的控制模型。3.通过对比模型输出的计算值和机组运行的实测值,验证了模型的正确性。应用K均值聚类算法得到了一段时间内机组的四个典型工况,并在工况点下用小偏差线性化法对模型完成线性化,最后运用增益调度控制,对非线性模型构造了控制器,通过三组参数的定值扰动试验,验证了控制器的有效性,实现了机组在大范围变负荷工况下机组功率的快速跟踪。
[Abstract]:In recent years, the new energy generation is developing in full swing, but the thermal power still occupies the leading position in the electric power production structure of our country, and the primary energy structure of our country decides that coal is the main fuel for the thermal power generation unit in our country. With the increasing requirements of environmental protection and energy saving and emission reduction, thermal power units are bound to develop to large capacity and high parameters. Supercritical and even ultra-supercritical DC units are becoming more and more mainstream. Therefore, it is necessary to do more in-depth research on the large capacity DC unit. It is a prerequisite to establish a model suitable for the design of control system of ultra supercritical DC unit. In order to achieve the above purpose, this paper has carried out the following work: 1. The heat storage of supercritical once-through boiler is analyzed. The distribution of the specific enthalpy and pressure of the working fluid with the furnace height in the water wall is obtained by using the mechanism analysis method. Based on the IAPWS-IF97 zoning standard, the water wall is divided into the supercooled water section, the transition section and the superheated section. Then the heat storage formula of water wall and superheater of once-through boiler is deduced by using the law of conservation of mass and conservation of energy. Finally, the design parameters of 1000MW unit boiler in Jianbi Power Plant are used to calculate the heat storage of the boiler. Through the analysis of the data, it is concluded that the water wall heat storage of the tower once-through boiler is about the same as that of the superheater. Metal heat storage is far greater than working fluid heat storage, boiler heat storage can be approximately replaced by metal heat storage. 2. 2. In structure, the once-through boiler unit is divided into pulverizing system, boiler system and steam turbine system. For the three systems, the model is constructed by using mechanism analysis method, and the heat storage data of once-through boiler is introduced into the modeling process of the boiler system. The model is modified and a general model structure suitable for supercritical DC unit is constructed. Then the unknown parameters and undetermined functions of the unit model are obtained by using the historical data of Jianbi Power Plant # 14 machine operation, regression analysis and genetic algorithm identification. Finally, a control model with three inputs and three outputs is constructed. The correctness of the model is verified by comparing the calculated values of the model output with the measured values of the unit operation. By using K-means clustering algorithm, four typical operating conditions of the unit are obtained for a period of time, and the model is linearized by the small deviation linearization method under the operating conditions. Finally, a controller is constructed for the nonlinear model by using gain scheduling control. The validity of the controller is verified by the constant disturbance test of three sets of parameters, and the fast tracking of the unit power is realized under the condition of large range variable load.
【学位授予单位】：华北电力大学(北京)
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TK229.54

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