河南职业技术学院

毕业设计（论文）

题 目 PLC的锅炉温度控制系统

系（分院） 电气工程系 学生姓名 孔永婷 学 号 11112036 专业名称 电气自动化 指导教师 徐瑞丽

2013年11月8日

目 录

1.1课题背景 ····································································· 4 图 3-4 系统硬件连线图 ····················································· 14 3.4 PLC控制器的设计 ···················································· 14 控制器的设计是整个控制系统设计中最重要的一步。首先要根据受控对象的数学模型和它的各特性以及设计要求，确定控制器的结构以及和受控对象的连接方式。最后根据所要求的性能指标确定控制器的参数值。 ···················································································· 14 3.4.1 控制系统数学模型的建立 ·········································· 14 在本控制系统中，TT1(出口温度传感器)将检测到的出口水温度信号转化为电流信号送入EM235模块的A路，TT2(炉膛温度传感器)将检测到的出口水温度信号转化为电流信号送入EM235模块的B路。两路模拟信号经过EM235转化为数字信号送入PLC，PLC再通过PID模块进行PID调节控制。具体流程在第四章程序编写的时候具体论述。由PLC的串级控制系统框图如图 3-5： ·································································· 15 如图3-5 串级控制系统框图 ··············································· 15 3.4.2 PID控制及参数整定 ··············································· 15

4.3.3 控制程序及分析 ··········································· 20 因为由AIW0和AIW2输入的是6400--32000的数字量，所以要转换为实际的温度要进行运算，运算公式为： ··················· 20

T?(D?6400)?100 公式（4-1） ······························ 20

32000?6400其中，T为实际温度，D为AIWO和AIW2输入的数字量。 20 PLC的内存地址分配见 表4-1 ·································· 20 控制程序如图4-14—图4-所示 ： ···························· 21 主程序： ···························································· 21 图4-14 控制程序1 ··············································· 21 主调节器程序： ···················································· 21 副调节器程序： ···················································· 23

·············································································· 23

第五章 组态画面的设计 ······································ 24 本章详细的讲解一个组态系统的建立和设计。 ············· 24 5.1 组态变量的建立及设备连接 ···························· 24 5.1.1 新建项目 ···················································· 24 双击组态王的快捷方式，出现组态王的工程管理器窗口，双击新建按扭，按照弹出的建立向导，填写工程名称。然后打开刚建立的工程。进入组态画面的设计 ········································ 24

1.新建画面 ························································· 24 进入工程管理器后，在画面右方双击“先建”，新建画面，并设置画面属性，图5-2所示： ········································ 25

图5-2 画面新建 ··················································· 25 要实现组态王对S7-200的在线监控，就先必须建立两者之间的联系，那就需要建立两者间的数据变量。基本类型的变量可以分为“内存变量”和I/O变量两类。内存变量是组态王内部的变量，不跟被监控的设备进行交换。而I/O变量是两者之间互相交换数据的桥梁，S7-200和组态王的数据交换是双向的 ····················· 25

5.2 创建组态画面 ·············································· 25 5.2.1 新建主画面 ················································· 25 如图 5-9所示，高温报警用来显示当温度高于95°C的时候，等会变红闪烁，加热炉上的指示灯用来指示加热炉的加热状态。 ·············································································· 25

图5-9 控制系统主画面 ········································ 26 5.2.2 新建PID参数设定窗口 ·································· 26 图5-10 PID参数设定窗口 ····································· 26 如图5-10所示，PID参数设定窗口，用来设定主控制器和副控制器的PID参数值，可与PID参数的整定。 ······················ 26

5.2.3新建实时曲线 ·············································· 26 实时趋势曲线可在工具箱中双击后在画面直接获得。实时趋势曲线随时间变化自动卷动，可快速反应变量的新变化。如图5-12所示:··········································································· 26

图5-12 实时曲线窗口 ·········································· 27 5.2.4 新建报警窗口 ·············································· 27 图5-15 实时报警窗口 ·········································· 28 图 6-1 监控主画面 ··············································· 29 图 6-2 温度实时曲线 ············································ 29 控制器起到了调节作用，最后温度稳定在了设定温度上，但是调节时间太长，大约10min左右，所以，我们需要增大Kc。点击主控控制画面的参数设定窗口，可以显示PID参数设定界面。参数设置如图 6-4所示： ······················································ 30

6.3 查看数据报表 ················································ 30

点击主画面的数据报表窗口，出现报表窗口，点击报表查询，可以查看报表记录的数据。如图 6-7所示： ························································································· 30

图 6-7 报表查询 ·················································· 31 记录的数据如图 6-8所示： ···································· 31 为了测试系统的的稳定性，我们把温度设定为80°C，所得到的控制曲线如图6-9所示： ··········································· 31

图6-9 60-80时的控制曲线 ··································· 31 如图所示，当设定温度改变时，系统是比较稳定的。 ···· 32 当实际温度超过85°C 时，会出现报警画面，如图6-10所示： ·············································································· 32

系统报警在工业生产中有着重要的作用。 ··················· 32