基于ia的燃煤电厂给水控制系统设计coal-fired power plants based on ia feed water control system design.docx

基于 I/A 的燃煤电厂给水控制系统设计
摘要
给水控制系统的目标似乎很简单,就是为锅炉提供足够的水量以达到需要的蒸发率。但面对越来越高的机组控制品质指标,它又是一个十分复杂的任务。即使在调节基础的汽包水位时,也会遇到许多困难,而这恰恰是整个控制系统中决定性的部分。锅炉侧的各种扰动影响也使得系统设计的鲁棒性成为研究重点,事实上,这些扰动带来的负面效果还会随着锅炉负荷的变化而时大时小。
设计者的任务是在最宽泛可行的操作条件范围内提供合适的控制方案, 也就是即安全又省力。为了做到这点,必需理解给水系统和蒸汽系统的细节机制,并充分考虑操作的需求。本文从给水控制系统的原理出发,分析了锅炉汽包水位的动态特性,介绍了给水控制系统中单冲量和三冲量控制系统的作用和区别。基于 I/A 系列 DCS 系统对电厂给水系统的控制过程进行了详细设计和分析。应用了 I/A 系列 DCS 系统中高可靠性的硬件和冗余结构,并使用系统自身提供的标准软件功能模块设计了串级 PID 控制回路以及低负荷时单冲量控制和高负荷时三冲量系统之间的切换。最后通过 Matlab 软件的 Simulink 组件对系统进行了仿真,分析了单冲量控制和三冲量控制系统各自的优缺点和应用范围,对锅炉负荷变化下的水位控制进行了仿真分析和给水泵最小流量控制的仿真分析。
关键词:I/A,分散控制系统,模拟量控制,锅炉给水控制,自选择
DESIGN OF FEEDWATER CONTROL SYSTEM FOR COAL-FIRED POWER PLANT BASED ON I/A SERIES
ABSTRACT
The purpose of the feed water control system is to supply sufficient water for the boiler to satisfy the rate of vaporization, but it always e plex task. Various disturbances and load changes make the design of the system plicated.
The basic requirement of feed water control is to provide an appropriate control scheme in the range of operation conditions while taking account of safety and efficiency. To reach this goal, it is necessary to understand the details of feed water and the steam system. Base on the principle of the feed water control system, this paper focuses on the dynamic characteristic analysis of the boiler water level in response to the feed water and other operation conditions. After that, design of the power plant feed water control system based on the I/A Series DCS system is presented. Using the standard function block offered by the hardware supplier, a cascade PID control system is constructed with the switch- functions between one-element control and three-element control. Simulations on the MALTAB software platform are practiced. The advantages of one- element or three-element control schemes and their best choosing are addressed. Simulate the drum level control with the change of load and feed water pump minimum flow control.
KEYWORDS: I/A, DCS System, MCS,