电厂水汽监控系统介绍(硕士论文).doc

摘要 在热中，水汽品质是一项重要指标。好的水汽品质可以提高热力设备的性能，延长设备的使用寿命，节约能源，减少事故发生率。反之水汽品质将会给电厂的热工设备造成不同程度的损伤，给机组的安全和电厂稳经济运行带来隐患。所以水汽采样和化学加药是电厂热工过程的两个重要环节。 本文根据水汽采样和化学加药的工艺特点，从硬件和控制算法两方面着手设计热厂化学加药控制系统，采用上位机和下位机相结合的上位机用工业计算机和组态软件成友好的人机界面，方便了系统的操作；下位机采用西门子S7 400H PLC进行数据采集和化学加药控制。用工业以太网管理层，负责上位机和下位机之间、本系统和电厂其它系统之间的通信现场总线构成现场设备的控制层，负责现场设备和PLC间的数据传输。 从上位机、下位机、以太网到现场总线均采用了冗余结构，来提高监控系统的可靠性。并把这样的系统作为电厂DCS的子系统。为提高系统的实时性，本文研究了DCS的通信问题介绍了一些提高通信能力的方法。 随着电厂规模的日益扩大，工艺水平的不断提高，要求更控制技术来满足工艺的需要。化学加药控制系统的非线性、大时滞、时变的特点，常规的控制方法难以获得满意的控制效果。为了提高系统控制的鲁棒性自适应，本课题将模糊控制引入到热电厂化学加药控制系统中。在算法方面，经过研究决定采用参数自适应模糊PID自动加药控制代替手动控制或是传统PID控制，并用仿真曲线来分析其动态性能和抗扰动能力仿真结果表明，该策略的控制效果优于常规的PID控制它能适应对象参数的变化，具有较强的鲁棒性和自适应能力。 关键词:现场总线；加药；时滞系统；模糊PID控制； Abstract In the thermal power plant,he parameters of water and steam of thermal system is a importance target. The good parameters of water and steam of thermal system can improve the performance of thermal equipment, and prolong the useful life of equipment, the using of devices, and save energy, reduce the ratio of the accidents. Contrarily, it will cause varying degrees of damage inthermal equipment of the Power Plant, and bring hidden troubles in the secure and economic running of the power plant, so, the chemical vapor sampling and Dosing is an important link for thermal power plant. On the bases of the Technological requirements of the water and steam of thermal system chemical and the dosing control system, the hardware and control algorithm is designed in the paper. In the hardware design, the upper and the hypogynous are combined in the design, the upper of the system is composed of PC and SCADA to be made of the friendly Man and Machine Interface, and it facilitates the operation of the system. The hypogynous of the system adopts Siemens S7 400H PLC to collect data and to control the process of the dosing control system. Industrial Ethernet is used of the management, and sees to communication between the upper and the hypogynous or between the system and other plant systems. FCS is u