王冬萌的大学设计(完结).docVIP

摘 要 火力发电厂在我国电力工业中占有主要地位，是我国的重点能源工业之一。大型火力发电机组具有效率高、投资省、自动化水平高等优点，在国内外发展很快。给水控制系统是火电厂非常重要的控制子系统。汽包水位是锅炉安全运行的重要参数，同时它还是衡量锅炉汽水系统物质是否平衡的标志，因此水位控制系统一直受到重视。 本文第二章首先讨论了给水系统的控制任务，介绍了常规水位控制系统的控制原理以及测量部分、控制器部分和执行器部分的结构。第三章分析了汽包锅炉给水系统的动态特性，介绍了水位、给水量、和蒸汽量的测量方法，分析了三冲量的扰动对控制系统的影响。第四章中集中讨论了锅炉水位控制略, 探讨了汽包锅炉在热工控制上的技术特点，具体介绍了单冲量、双冲量和三冲量等控制方式。在文章的最后，对给水系统进行仿真，选定了串级三冲量的控制策略，用MATLAB软件搭建了控制系统结构图。经过仿真，整定了控制器的参数，取得了较好的控制效果，并验证了控制系统的抗干扰能力和对被控对象参数变化的适应性，均满足控制要求。 关键字：汽包水位 三冲量 控制策略 仿真 Abstract The power plant is a major part of the power industry in our country, as well as one of the most important energy industries. Large turbine-generator units have the advantages of higher efficiency, less investment and higher level of automation, which develop rapidly around the world. Feed-water control system is a very important subsystem of the power plant. Water level of boiler drum in power station is one of the main control parameters for safe operation, which reflects the balance of boiler load and feed-water. Thus the water level control system is always highly concerned. Chapter two firstly discussed the target of the water level control system, then introduces the theory of common water level control system and the structures of its transducers, controllers and actuator. Chapter three analyzes the dynamic characteristics of drum boiler feed-water system, introduces the measurements of water level, feed-water flow and steam folw(the so-called three impulses). The impact of three impulses’ disturbances on the control system is discussed as well. In chapter four we mainly discussed the control strategics of water level control system. Such as single impulse, pairs of impulse and three impulses, etc. At the end of the whole article, we made simulations of feed-water system. We chose the three impulses as our control strategic and built up a simulating project with MATLAB. Throgh the simulations, we have adjusted the control parameters to ideal values and got satisfed control performances.