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一本课题的研究意义、研究现状和发展现状1. 本课题的研究意义 锅炉是工业火力发电厂企业的重要动力设备，它是火力发电厂三大主机之一，锅炉工业的发展影响着火力发电的发展和大电站的建设，此外，锅炉还是轻工业生产中的热源和动力源，如为蒸馏、化学反应、干燥蒸发等提供热能，为风机、压缩机、泵类提供动力。由此可见国民经济各个部门的发展离不开锅炉工业的发展，它在我们建设有中国特色社会主义，大力发展经济，实现现代化的进程中，发挥着重要作用。 气包水位是锅炉系统正常运行的重要参数，维护锅炉水位在一定范围内变化，是锅炉水位控制的重要任务之一，也是保障蒸汽机和锅炉安全运行的重要条件。如果气泡水位过高，会影响汽包的汽水分离装置的正常工作，导致锅炉出口蒸汽带水和含盐量过大，使过热器热面结垢甚至遭到破坏，影响机组的正常运行和经济性指标；如果汽包水位过低，会使锅炉水循环工况破坏，造成水冷壁供水不足而被烧坏，所以研究锅炉汽包水位的控制方法有着重要意义。 2. 研究现状和发展趋势 我国工业锅炉的自动化控制，经历了三四十年代的单参数控制，四五十年代的单元组合式综合参数仪表控制从六十年代开始，人们对锅炉水位系统进行了更深入的研究，采用更先进的计算机控制方法，如数字PID控制、最优控制、自适应控制等。在控制结构上采用串级 -前馈-反馈控制。针对控制锅炉对象的滞后特性，采用Smith纯滞后补偿控制等。比如：文献针对当时锅炉水位控制中大多数采用的DDZ-II型电动单元组合仪表电路，故障率高，调节效果差等特点，设计并制作出一种采用PID调节原理的新型智能水位控制仪。 锅炉工业的迅猛发展是近几年的事情，国外的锅炉工业50年代发展最快，70年代达到高峰。一直以来，用单片机实现锅炉控制是控制领域的一个典型的问题，伴随着控制理论和技术的发展，锅炉自动化控制水平也在逐渐提高，锅炉的自动化控制，经历了30年代的单参数控制，40年代的组合仪表复合参数仪表控制，以及60年代兴起的计算机过程控制几个阶段。而用单片机实现锅炉的控制，也是近几年才发展起来的，是一个逐渐深入的过程，虽然与其他发达国家相比还存在差距，但是在此方面的进步却是很大的。 国外许多学者正深入地研究汽包水位智能控制方法。1974年英国的E.H.Mamdani ，成功的将模糊控制应用到锅炉和蒸汽机控制中，此后，模糊控制得到了广泛的发展并在现实中得到了成功的应用。国内的许多学者对汽包水位模糊控制也进行了深入的研究，如哈尔滨工程大学的夏国清等针对锅炉水位问题，提出了一种自学习模糊控制方法，并进行仿真研究，验证了模糊控制对汽包水位模型参数变化不敏感，抗干扰能力强等优点，解决了对象数学模型不精确时控制器的适应性问题。 但是，常规的二维PID模糊控制存在比较大的静态误差和多级继电器特性，降低了它的精度,所以有必要对模糊控制进入更深入的研究，以便提高对汽包水位系统控制的性能。近年来，集散控制系统系统（DCS）迅速发展并为锅炉控制提供了强有力的手段，特别是在集散控制系统中采用模糊控制等高级算法已经成为集散控制系统发展的一个重要组成部分。总的来说，汽包水位控制到经历了一个由单元组合式仪表到计算机控制，由传统的PID控制到更高级的智能控制，由直接现场到集散控制的发展过程。二主要设计内容采用三冲量水位控制系统，以锅炉水位为主控信号，蒸汽流量为前馈信号，给水流量为控制器的反馈信号；采用以单片机为核心的硬件电路，实现锅炉水位的智能控制系统。3 研究方案： 三冲量控制系统从结构上来说，是一个带有前馈信号的串级控制系统。液位控制器LC（主调节器）与流量控制器FC（副调节器）构成串级控制系统。蒸汽流量的波动是引起汽包液位变化的因素，是干扰作用;要实现蒸汽流量扰动下水位不变的设想，三冲量水位控制系统以蒸汽流量为前馈信号，给水流量为控制的反馈信号，锅炉水位是主冲量信号，首先用变送器从锅炉汽包中采集到的这些物理参数转化为模拟信号，然后通过A/D转换器转换成单片机可识别的数字信号，将其送入单片机中进行处理，随后将输出信号再通过D/A转换器转换为模拟信号，最后将处理后的信号送入执行器，执行器通过控制给水流量来完成对锅炉汽包水位的调节工作。同时把水位进行显示，超标时进行报警处理，同时具有人机交互功能，和显示功能。 锅炉液位检测变送器给水流量变送器蒸汽流量变送器 执行器 A/D D/A 人-机交互 显示 报警 通信 单 片 机 设计方案框图位变送液器重点：设计一个以单片机8051为核心的智能锅炉水位控制系统难点：如何用软件实现模糊前馈控制和PID控制途径：1，进入网上图书馆查阅相关质料 2，从书店借阅相关书籍 3:，充分利用使用实验室里的控制系统设备分析了解 工作计划1-4周 搜集资料，熟悉课题，明确设计目的和要求， 确定设计整体框架，准备开题报告 5 周 确定设计方案 仪表选型6-7 周 做好硬件设计8-9 周 做好软件设计10-12 周 软件，硬件调试，修改13-15 周 撰写毕业设计16-17 周 毕业答辩参考文献 1陈振山，高明帅，张红侠，火电厂锅炉汽包水位的智能控制研究J，科技信息.p02012,3；【2】董海运，肖航 船用锅炉汽包水位模糊控制研究J.中国舰船研究 2009,01；【3】高雪峰 浅谈蒸汽锅炉水位自动控制J.科技信息 2009,04【4】彭雪峰，张怡典 智能锅炉水位控制系统设计R .九江职业技术学院报告 2012 03.【5】陆柳延，王妹婷，齐永峰，吕学智，锅炉水位的模糊控制及其仿真实现 N 扬州大学学报（自然科学报） 2013:02【6】马跃春，基于plc的蒸汽锅炉双冲量水位控制J.科技信息 2013 ,10【7】张奠基 大容量锅炉汽包水位的全程自动控制J. 科协论坛 2013,09【8】郭庆祝 岳书朋 船用锅炉水位控制系统J .中外船舶科技 2008,02【9】李成浩 锅炉水位PID控制与模糊控制研究 J .2012,2110 Chen Ye, Cang Xiaojin, Peng Peng. Network control system based on OPC middleware technologyJ. Dianli Zidonghua Shebei/Electric Power Automation Equipment, 2011, 31: 100-104+108. 11 Xu Jianguo, Zhong Weimin, Tong Yu. Testing Platform for Advanced Process Control Algorithm Based on Matlab7.0 and KINGVIEWN. Chinese Journal of Scientific Instrument, 2006, 6: 542-544. 12 Li Anfu, Cui Yaling. OPC-based data communication between Matlab and KingViewJ. Electric Power Automation Equipment, 2007(7): 113-115.参考外文文献及其译文 Intelligent Control System of Water Level for Boiler Drum WU Mingliang1, WU Mingyong2, HUANG Jiankang3, SHAO Ling31. Electromechanical Academy, Lanzhou University of Technology, Lanzhou 730050, P. R. China E-mail: 2. Peili Oil Academy of Engineering , Lanzhou City Academy, Lanzhou 730050, P. R. China 3. Key Laboratory of Non-ferrous Metal Alloys and Processing under the management for Ministry of Education, Lanzhou University of Technology, Lanzhou 730050, P. R. China E-mail: Abstract: WinCC configuration software and OPC technology as a breakthrough, communication integration of MATLAB and WinCC is realized. The real-time data exchange problem among different monitoring systems is solved based on OPC technology. That combine with strong engineering calculation ability of MATLAB and characteristics of real-time data collection for Siemens configuration software WinCC. The simulation results show that OPC is the communication interface between the Client MATLAB and Server WinCC. It can preferably realizes seamless transmission and experimental test of fuzzy self-adaptive PID intelligent control algorithm for boiler drum water level, and better satisfy real-time data, high efficiency requirements of process control for the boiler. Key words: OPC Technology, MATLAB, WinCC, Real-Time Data Exchange, Fuzzy Self-Adaptive PID 1 Introduction In the design of industrial boiler control system, how to effectively realize intelligent control algorithm is always the universal concern problem of the industrial boiler automation control areas. WinCC is the man-machine interface (HMI) software. It can solve visualization and control tasks in the production process and process automation, and develop acquisition system of supervisory control and data in the management level. It has high practicality and flexible configuration 1. But its ability of data processing is weak, and it is not easy to realize complex control algorithm. However, there are numerous advantages in MATLAB. For example, it is a kind of professional software for mathematical analysis and engineering computation, providing a powerful ability of data processing and open interface of application programming, having a rich toolbox of control algorithm, and completing modeling and simulation of dynamic complex control system. But WinCC cannot directly communicate with the industrial control equipment, carry on real-time operating and controlling, and effectively verify the algorithm. The OPC bases on a set of OLE and COM/DCOM technology of Microsoft Windows operating platform. It realizes standards of software interface between the different on-site equipments and applications. And it also adopts Client/Server model, in order to provide the highly effective information integration and object model component of standard interface of interactive function. Users design corresponding Client 2 ccording to OPC Server provided by hardware developers, and as a result the data exchange of different systems can be realized. If MATLAB is *This work is supported by National Natural Science Foundation (NNSF) of China under Grant 50675093. combined with WinCC by the OPC technology, complex control algorithm is used by MATLAB language, and then function of data acquisition and friendly human-machine interface are realized with WinCC, respective advantages of MATLAB and WinCC will be beneficial to be played. 2 OPC Interface Technology OPC (OLE for Process Control) is component model interface providing highly efficient information integration and interactive function for industrial applications. It is referred to object linking and embedding technology in process control. Due to maintenance and management of OPC Foundation institutions, the specifications of OPC DA (Data access), AE (Alarm and event) and HAD (Historical data access) has already been launched. At present, it is the most catholically applied that the OPC DA of data access standard. The standard is used to complete process of data exchange between process controller and HMI equipment or other clients. The datum read include data type, time label, quality and statement of numerical quality. The client can read the process data and write command into OPC server, and the command is transmitted to the scene controller3. The specification of OPC technology contains Server and Client, using the Client/Sever mode. Server is the supplier of data and Client is the user of data. They establish a complete set of rules between hardware supplier and software developer. The driver of hardware device and the communication program are encapsulated to independent OPC Server. It transmits control command and measurement data to Client. Only to obey the protocol of OPC data interface, OPC Client is generally designed and developed by the user. As a result, it can be realized that datum is acquired from OPC Client. An OPC customer can connect to one or more OPC Server, and multiple OPC Proceedings of the 30th Chinese Control ConferenceJuly22-24, 2011, Yantai, China4461customers are also allowed to simultaneously connect to the same OPC Server. Server consists of three types of objects: Server, Group and data Item, according to standard code of access for OPC data. Server has all information of Server objects and is a container of group objects, providing function of creating and operating the OPC group objects for OPC Client. Group has all the information of this group objects and is a container of OPC item, offering the mechanism of organization and management. Item is a specific process variable and the smallest unit of read-write, representing a physical connection which is from OPC Server to data source. Item cannot be directly accessed by OPC Client procedure but can be realized by accessing OPC group object containing items. Data structure of each data item contains three variables: Value, Quality and Time stamp. The OPC specification describes two kinds of access interfaces. They are Automation interface and Custom interface supported by OPC Server. The custom interface of OPC data access is a group of COM interface and can be developed and visited by high-level programming languages such as C/C + +. The realizable method of custom interface for OPC Server is complex, but fast and efficient. And the best performance of OPC Server can be exerted by this interface. However, the automation interface of OPC data visit is defined as standard interface based on scripting language of programming. It makes COM interface convert to automation OLE interface, and makes OPC server visited by expository language and macro language become possible. And it is developed and completed by senior languages such as Visual Basic. Moreover, the realization method of automation interface for OPC data visit is simple, but slow and has less function. 3 Fuzzy Self-adaptive PID Control of Water Level for Boiler Drum Presented The water level of boiler drum is an important parameter to ensure safety in production and provide steam of superior quality. Because many considerations such as load changes, inlet and outlet water speed and water quality influence the water level, it is a typically time-varying and nonlinear system. If a conventional method of automatic control is adopted, it often cannot be done that the desired control effect and the stability of drum water level. The accommodation of drum water level has certain characteristics of delay and inertia, namely, when step transition has taken place to the steam flow and water flow given, the water level of object regulated cant immediately follow with linear changes, especially there is a phenomenon of false water level when step transition has happened to the steam flow. Consequently, it is presented that fuzzy self-adaptive PID control of cascade three-level impulse module 4, 5 was adopted for the water level of boiler drum, and its scheme of control system is shown in Fig.1. Fig.1 Elementary diagram of fuzzy adaptive PID control for drum water level Inside the structure, the steam flow and water flow given which act on subloop at the same time arrive at phase equilibrium in the stable condition. But when one of them changes, due to the interference or spontaneous disturbance, the controller of water flow given for output will act on the actuator advanced regulating of water flow given and make water level invariant basically by conventional PID arithmetic, according to the deviation between the steam flow and water flow given. The parameter regulator in the first-order of major loop use self-tuning controller of fuzzy PID parameter. When the water level deviation is the given value, the adjustment value of water flow given is got by fuzzy PID arithmetic. Moreover, the water flow given controller changes water flow given, making water level return to the given value. 4 The Realization of Real-time Control on the Simulink and WinCC Between MATLAB and WinCC, the real-time transmission of data and seamless integration of system are designed and implemented. They provide intelligent control algorithm of designed calibration with an effective approach, playing an importantly practical value to field debugging of the boiler control. WinCC which can serve as either OPC Client or OPC Server has good openness and flexibility, can realize data exchange with external program safely and reliably and fully supports OPC standard. Through OPC- DA Server of WinCC, the real-time data in system of field process control can be obtained and related process variable value can be changed real-timely in system, completing effective control of system parameter 6. Fig.2 Structural diagram of MATLAB and WinCC process control 44624.1 System Structure System structure of realization process control for MATLAB and WinCC is shown in Fig.2. This system acquires data of field device with Siemens PLC S7-300 (lower computer), makes configuration software WinCC (host computor) act on the data total control platform and OPC Server and uses MATLAB as OPC Client for algorithm design, real-time control and analysis of control result. WinCC communicates with S7-300 through Profibus. 4.2 The Realization of Fuzzy Adaptive PID on Simulink and WinCC The Matlab7.0 above software has OPC toolbox which can undertake OPC Setting. Simulink7.1 integrates module sublibrary of OPC toolbox which includes OPC read block, OPC write block, OPC Configuration and OPC Quality Parts. MATLAB is used as a powerful Client, in order to realize analysis of control system, algorithm write and the graphic display of control algorithm effect 7. Using OPC Toolbox, dynamic data exchange of MATLAB and WinCC is realized, which has some main steps 8 as follows: (1) Commands of OPC register, OPC Server registered and the corresponding Windows core components used by Client are applied. (2) In the OPC Client and Server, proper DCOM configuration is carried on. Firstly, obtain node name in the network and guarantee the objects to join up in the OPC Toolbox and OPC Server. Secondly, download and install Client development kit including OPC Core Components 2.00 Redistributable 2.20.msi controls. (3) Open Simulink and find the module sublibrary of OPC toolbox in which the OPC read block, OPC write block and OPC Configuration are, these three modules are pulled to new model window. Double click the OPC Configuration, then choose and add OPC Server.WinCC to configure OPC Clients/Add/Select. Subsequently, double click to open Setting window of OPC Read parameter. First of all, OPC Server.WinCC is chosen and added through configure OPC Clients/Add/Select. Secondly, the shuiwei.cj, shuiliuliang.cj and zhengliuliang.cj of localhost/OPCServer.WinCC are selected in “Add Items”. In the same way, add qishuiwei to OPC Write. Note that other parameters in the OPC read and OPC write are set for Synchronous (de-vice) and Sample time is 0; synchronous communication mode is chosen in the Write mode and Sample time is set for 0. (4) In OPC Server WinCC, create variables, establish OPC driver, set related operation parameters and ensure that OPC server is running when mutual communication. The real-time control system in Simulink is shown in Fig.3. It mainly includes three parts: OPC read block (acquisition value of real-time read), cascade controller of fuzzy self-adaptive PID and OPC write block (control variable of real-time). WINCC display picture of reading and writing data, and real-time datacurve of OPC communication in MATLAB OPC Server are shown in Fig.4. It could be seen from this curve that according to the operation state, the system adjusts three parameters of the PID controller on line such as Kp, Ki and Kd, makes control system have good dynamic and static performance index in order to achieve optimization of system performance index and overcome unmodifiable disadvantages of traditional PID controller parameters. Fig.3 Block diagram of Simulink control system Fig.4 Real-time data curve of WinCC data display and OPC communication 5 Conclusions Through establishing a simulation model of OPC technology, corresponding control algorithm of OPC Client established in Simulink communicates with OPC DA Server of industrial control software WinCC, obtains object process data and controls the corresponding boiler equipment in the WinCC. In simulation system, various control algorithms are edited by MATLAB, and measurement verification is directly carried out through this Client/Server mechanism. So not only actual performance of control algorithm can be inspected, but also more importantly debugging data and information can be got for the system commissioning operation to provide important reference. Engineering practice shows that this method realizes the system intelligent control without increasing any system cost, has some advantages such as high control accuracy, good stability and short development cycle, and is a beneficial attempt of intelligent control realized for engineering method. The engineering method offers a new 4463way of thinking for application of intelligent control algorithm in industrial control process. 1 Weng Yifang, Duan Zhenqang, Lian Xiaoqin. Application of configuration software WinCC in logistics automatic control system. In: Sixth International Symposium on Instrumentation and Control Technology: Sensors, Automatic Measurement, Control and Computer Simulation, vol. 6358 , 2006. 2 Oh. Se-Young, Kim. Wan-Ho, Yune. Hyoung-soon: The double exposure strategy using OPC & simulation