600MW直流机组过热汽温调节系统
摘 要
600MW单元机组过热汽温控制通常采用分段控制系统，由二段相对独立的串级控制构成，串级控制系统对改善控制过程品质极为有效。过热汽温的控制系统对于电厂的安全经济运行都非常重要，整个系统是维持过热器出口蒸汽温度保持在允许的范围内，并且保护过热器是管壁温度不超过允许的工作温度。
在电厂整个控制系统中，影响过热汽温的因素很多，主要有蒸汽流量扰动、烟汽流量扰动、减温水量扰动三方面。而喷水减温对过热器的安全运行比较有利是目前广泛采用的方法。
在串级控制系统中副调节器所在的内回路能快速消除减温水量的自发性扰动和其他进入内回路的各种扰动，而主调节器所在的外回路保持过热汽温等于给定值。并且系统实现了自动跟踪和无扰切换，保证机组安全经济的运行。对于过热蒸汽的采集实现了二冗余，提高了系统的可靠性。
整个过热汽温控制系统是用N—90实现的，且系统切换和逻辑报警线路全面，具有较高的可靠性。
关键词 电力系统，过热汽温，串级控制
I
沈阳工程学院毕业设计（论文）
Abstract
In this paper, The 600 MW unit machine set leads the hot air the control usually adopts a control system, constituting from two opposite and independent string classes control, string class control the system controls the process quality to the improvement extremely effective .Lead the control system of the hot air for the power station of safe economy circulate all count for much, the whole system is to maintained the hot machine to export the steam temperature to keep within the scope of allow of, and protected the hot machine is a work temperature that takes care of the wall temperature not to exceed to allow.
In the whole control system of power station, affected the factor of the hot air a lot of, mainly have the steam discharge to move, the smoke current of air quantity move, reduces the water to move three aspects .But spray the water to reduce to lead the safe movement of the hot machine more beneficial is an extensive adoptive method currently.
In string class control system vice- modulator place of inside the back track can remove the self-moving sex of reduce to move quickly and other enter inside the back track of various move, but the outside back track of the main modulator place kept the hot air to be equal to plant certainly .And the system carried out to follow automatically and have no the cut over, guarantee the machine set safety economy of movement .For led the hot steam to collect to carry out two redundancies, raise dependable sex of the system.
Whole lead what the hot air control system is to use the N-90 to carry out, and the system cut over to report to the police the circuit with logic completely, have the higher and dependable.
Key Words electric power system, serial control , superheated steam temperature
II
600MW直流机组过热汽温调节系统
目 录
摘 要 .............................................................................................................................................. I Abstract .......................................................................................................................................... II 目 录 ........................................................................................................................................... III 1 引 言 ....................................................................................................................................... 1 2 DCS控制系统简介 .................................................................................................................. 2
2.1分散控制系统的产生 ........................................................................................................ 2 2.2分散控制系统结构 ............................................................................................................ 3
2.2.1网络通信子系统 ...................................................................................................... 3 2.2.2过程控制子系统 ...................................................................................................... 3 2.2.3人机接口子系统（HMI） ...................................................................................... 4 2.3分散控制系统(DCS)的特点 ............................................................................................. 5 3 过热汽温控制系统概述 ........................................................................................................... 7
3.1过热蒸汽温度控制的意义和任务 .................................................................................... 7 3.2被控对象动态特性分析 .................................................................................................... 7
3.2.1锅炉负荷扰动下过热汽温的阶跃响应曲线 .......................................................... 8 3.2.2烟汽热量扰动下过热汽温的阶跃响应曲线 .......................................................... 8 3.2.3减温水量扰动下过热汽温的阶跃响应曲线 .......................................................... 9 3.2.4减温水量扰动与负荷扰动或烟汽量扰动的比较 .................................................. 9 3.2.5改善减温水量扰动下动态特性的方法 ................................................................ 10 3.3常规过热汽温传统控制策略 .......................................................................................... 10 3.4串级汽温调节系统 .......................................................................................................... 10
3.4.1过热汽温串级调节系统的组成 ............................................................................ 10 3.4.2串级系统的结构和工作原理 ................................................................................ 11 3.4.3主汽温串级控制系统原理 .................................................................................... 12 3.4.4串级汽温调节系统的分析 .................................................................................... 12
4 过热汽温的整定 ..................................................................................................................... 14
4.1串级控制系统方框图 ...................................................................................................... 14 4.2过热汽温的参数整定 ...................................................................................................... 15 5 SAMA图分析 ........................................................................................................................ 17
5.1控制系统SAMA图绘制 ................................................................................................ 17 5.2控制系统SAMA图分析 ................................................................................................ 18 5.3控制系统ＳＡＭＡ图绘制 .............................................................................................. 22 5.4控制系统SAMA图分析 ................................................................................................ 23 6 MATLAB仿真技术 ............................................................................................................... 27
6.1 MATLAB仿真技术的发展与应用 ................................................................................ 27 6.2 MATLAB仿真技术的特点 ............................................................................................ 27 6.3 MATLAB系统组成 ........................................................................................................ 28 6.4 MATLAB仿真 ............................................................................................................... 29 结 论 ........................................................................................................................................... 31
III
沈阳工程学院毕业设计（论文）
致 谢 ........................................................................................................................................... 32 参考文献 ....................................................................................................................................... 33 附 录1.1 ..................................................................................................................................... 34 附 录1.2 ..................................................................................................................................... 35
IV