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1、小初、宋体、加粗本科毕业设计（外文翻译）小三、宋体、1.5倍行距题目过长分两行，所填内容居中题 目 _基于PLC锅炉温度控制_ 系统 小三、宋体、1.5倍行距姓 名 杨宗豪 专 业 自动化 学 号 指导教师 金 楠 四号、楷体、加粗、1.5倍行距郑州科技学院电气工程学院 二一三年十二月外文翻译原文：基于PLC的锅炉温度控制系统的研究摘要：从锅炉的发展情况，PLC选型,系统软硬件设计，上下位机通信，组态程序开发设计等几个方面进行介绍。通过PLC实现的温度控制系统具有调试简洁、价格低廉、易于维修等优势，并且容易拓展到相应的工控领域，移植性较好对工控发展具有重要的意义。关键词：PLC;传感器；温度；
2、自动控制随着经济的不断发展，环境问题越发突出。锅炉作为供热系统中最重要的能源转换装置能源消耗巨大，每年全国锅炉燃烧消耗的能源占总产1/3以上。目前，国内大部分城市供热系统中运行的锅炉设备陈旧老化基本依靠人工操作，自动化水平低下，安全性能极差，燃烧效率不高，空气污染极为严重。因此，为锅炉配置自动化温度控制系统在当今环境污染日益严重的情况下就显得极为重要。1 基于PLC的锅炉温度控制的介绍本系统是基于PLC的锅炉温度控制，通过锅炉内部传感器对温度、流量等参数的反馈来对系统温度进行调控，实现锅炉温度的自动控制。PLC可编程控制器是一种将继电器控制器和计算机结合起来，通过安装程序,CPU中央处理单元为
3、核心与I/O设备相连接，使用在工控领域的计算机其构成与普通计算机略有不同，主要是由CPU、存储单元、I/O接口电路、电源等基础部分,外加扩展部分、编程器、外部设备等方面组成。PLC可编程控制器既能替代普通的继电器，又具有多种扩展功能，如A/D模块等。因此，PLC的运用为锅炉的自动控制提供了新的解决办法,使一些先进的控制方法得以应用。使用PLC可编程控制器对锅炉系统进行改造,实现对温度的自动控制,一方面可以提高燃烧效率，减少燃料的使用量和烟气中有害气体的排放,减少了空气污染；另一方面，PLC控制系统通过各种传感器检测锅炉内温度、压力、流量等相关参数，实现了对温度等参数的自动控制。减少了人工劳动环
4、节，基本上只需在机房控制室内就可以全面了解整个锅炉的运行情况，降低了人力成本、提高了系统的自动化管理水平。2 温度控制系统设计2.1 温度控制系统方案设计本设计以西门子S7-300可编程控制器为下位机，两台工业控制机为上位机。上位机通过工控软件实现报警等预警功能，下位机采用西门子S7-300可编程控制器，实现锅炉内温度、流量等自动控制，控制水平及安全性得到保证。系统被控对象为温度，利用PT100型热电阻传感器检测锅炉内部水温，然后通过温度变送器传给EM235模块，转换完信号经过PID的运算,调节后得到一个稳定的PID参数值,然后输入信号到可控硅的电压调节器来控制加热器的电压，达到调节温度的目的
5、。2.2温度控制系统硬件设计1）主机系统。使用两台工业控制计算机构成主机，其中一台作为主要控制机，另外一台为辅主机，构成双保险。组态软件使用西门子工控组态软件WINCCSP26.0。2）PLC可编程控制器。系统选用西门子公司SP-300PLC的可编程控制器。其模块化结构，易于实现分布式的配置以及性价比高、电磁兼容性强、抗震动冲击性能好，使其在广泛的工业控制领域中，成为一种既经济又切合实际的解决方案。多种性能递增的CPU和丰富的且带有许多方便功能I/O扩展模块(包括信号模块SM、通信处理器CP、接口模块IM等)。用户可以根据实际应用选择合适的模块。3）仪表设备。为了提高抗干扰能力，选用型仪表仪表
6、DDZ-IH输出为0123 45mA电流，保证系统的可靠性。仪表主要包括：流量变送、器压力变送器、温度变送器、液位变送器、含氧量变送器、微压变送器等。4）变频控制室。主要包括：电源控制柜、锅炉变频控制柜、循环泵变频控制柜、控制柜内配有各样型号的断电器接触器、继电器等，低压电器设备以完成电机的启动、停止。2.3温度控制系统软件设计2.3.1 PID指令算法 PID控制器根据系统参数的误差值,通过比例积分、微分计算出控制量来进行控制，故称为PID控制，或者PID调节。在工控领域中，PID至今仍在广泛使用。三种控制量各有特点，单独存在时优点与缺点都很明显，一起使用时又会有各种约束限制的问题，如何调节
7、出稳定的PID参数，就成为目前控制中最为重要的步骤。2.3.2 PID控制算法的特点1）比例(P)控制。比例（P）控制是最简单的一种控制方式，其控制器的输出与输入误差信号成比例关系。若产生偏差，控制器就发生作用调节控制输出，使被控量向减小偏差的方向变化。偏差减小的速度由比例系数Kp来决定，Kp越大偏差减小的越快。但这样会引起振荡，特别是在迟滞环节比较大的时候，比例系数Kp减小振荡发生的可能性就会减小，但同时也会导致调节速度变慢。比例控制的缺点是不能消除稳态误差，必须要有积分控制来辅助。 2）积分（I）控制。在积分控制中控制器的输出与输入误差信号的积分成正比关系。进入稳态后，如果控制系统存在稳态
8、误差，为了消除系统中存在的稳态误差，必须加入积分项。随着时间增大，积分项也会增大，因此即便误差比较小积分项也会随着时间的增加而加大，它的存在会进一步减少稳态，误差直至为零。所以比例积分（PI）控制器可以使系统进入稳态后无稳态误差。3）微分（D）控制。在微分控制下，控制器输出的微分增加了，输入误差信号的微分同时也会增加。而自动控制系统在对于误差的控制来说，会出现别的不必要的问题比如波动更严重的会失稳。这就是说，在控制器中仅引入“比例”项往往是不够的。比例项的作用仅是放大误差的幅值，但是加入的微分项却能够避免较大的误差出现。因为它可以预测误差变化的方向，但是微分控制会放大高频噪声，降低系统的信噪比
9、，导致系统抑制干扰的能力下降。也就是说微分控制不能消除余差。2.3.3 PID参数整定PID参数整定主要是调节P，Pi，Pt。改变系统的各项特性，使得系统达到满意指标。2.3.4 PID算法程序实现 在SP-300中PID功能是通过PID指令功能块来实现的，通过定时执行PID功能块。按照PID运算规律,根据当时的给定，比例-积分-微分数据，计算出控制量。3 PID程序设计 PLC控制程序是采用西门子编程软件S7V5.3来实现。首先输入模拟信号，将锅炉的当前电压通过数值显示出来。其次观看锅炉目前温度是否正常，报警指示灯是否能正常使用。启动程序，观察启动后位置，初始化PID参数，关闭程序，清零模拟
10、量，停止锅炉继续加热但仍显示温度。设定温度值，中断程序，调节PID参数，输出PID运算结果,输出模拟信号。4 组态模块设计1） 组态软件设计。本系统的组态设计部分软件选择是西门子WINCC组态软件，WINCC是一种功能强大，具有很好的开放性的软件。各种复杂的任务，WINCC均可以处理好。WINCC属于人机界面的组态工具,其最大的特点是能够以组态方式进行系统集成。只要将预设的各种软件模块进行简单组态，就可以轻松实现监控层的各项功能，缩短了系统集成时间，提高了工作效率。WINCC组态软件以微软系统作为平台，提供强大的编辑功能，而且本身载有丰富的图形资源，方便设计各种工业用图，而且方便编辑，同时因为
11、与计算机的通用性，减少了工作量。用户可以自行设计编辑函数，充分利用了开放性功能。由于都属于西门子公司，在使用WINCC组态软件时可以轻松对S7-300PLC系统中的变量进行创建,编辑及修改，极大的方便用户。 2）上下机位通信。将PLC与计算机连接，连接完成后在软件上设置通信。 3）系统调试。上下位机连接完成后，反复调整温度控制PID参数,以便得到最佳PID参数值。系统中出现震荡现象，通过加入微分调节，多次调试后得到最佳PID参数。5 结束语 本系统采用单回路PID控制，通过多次调节PID参数,得到一个响应快速,高精度控制的锅炉温度控制系统，完成了预定目标。由于使用组态设计的界面，使得本系统更加
12、简洁实用，对温度的控制更加灵活便捷，并且可以拓展到相关工控领域。Based on the research of PLC temperature control system of boilerAbstract: from the development condition of boiler, PLC type selection, system software and hardware design, communication up and down a machine, the configuration program design is presented in several
13、aspects, such as. By the temperature control system of PLC debugging the advantages of the simple, low cost, easy to maintenance, and easy to expand to the corresponding field of industrial control, good portability is of great importance to the industrial developmentKey words: PLC; The sensor; Temp
14、erature; The automatic controWith the continuous development of economy, the environment problem increasingly prominent. Boiler as the heating system is one of the most important energy conversion device energy consumption is huge, every year the national boiler combustion of more than one third of
15、total energy consumption. At present, the domestic most of the urban heating system in the operation of the boiler equipment aging basic rely on manual operation, automation level is low, safety performance is poor, the combustion efficiency is not high, the air pollution is very serious. Therefore,
16、 the configuration of automatic temperature control system for boiler in todays increasingly serious environmental pollution situation is extremely important.1 boiler temperature control based on PLC is introduced This system is based on PLC boiler temperature control, through the boiler internal se
17、nsor for temperature and flow rate feedback to system parameters such as temperature control, the automatic control of boiler temperature is realized. PLC programmable controller is a kind of combined relay controller and computer, through the installer, central processing unit CPU as the core and I
18、/O devices connected to its use in the field of industrial control computer is slightly different with ordinary computer, mainly by the CPU, memory cell, basic components such as the I/O interface circuit, power supply, plus extension, programmer, external equipment, etc. PLC programmable controller
19、 can not only replace the ordinary relay, but also has A variety of extensions, such as A/D module, etc. Therefore, the use of PLC for automatic control of boiler provides a new solution, some advanced control method to the application. Using PLC programmable controller for boiler system, realize th
20、e automatic control of the temperature, on the one hand can improve combustion efficiency, reduce fuel use and emissions of harmful gas in flue gas, reducing the air pollution; PLC control system, on the other hand, through a variety of sensors inside the boiler temperature, pressure, flow and other
21、 related parameters, realized the automatic control of the parameters such as temperature. Reduces the manual labor, basically just in the engine room control room can fully understand the operation of the boiler, reduce the manpower cost, improve the level of the automation management system.2 the
22、temperature control system design2.1 the temperature control system design This design by Siemens S7-300 programmable controller for the next bit machine, two industrial control machine for PC. PC through industrial control software to realize early warning functions such as alarm, under a machine a
23、dopts Siemens S7-300 programmable controller, realize automatic control, such as temperature, flow rate in the boiler control level and safety guaranteed. System for the temperature of the object, and using PT100 type thermal resistance sensors inside the boiler water temperature, and then passed to
24、 EM235 module temperature transmitter, convert the signal through the PID arithmetic, adjusted to get a stable PID parameter values, then the input signal to the silicon controlled voltage regulator to control the voltage of the heater, achieve the purpose of regulating temperature.2.2 the temperatu
25、re control system hardware design 1) the host system. Using two sets of industrial control computer host, one of them as the main control machine, another one is complementary host, make double insurance. Configuration software WINCCSP26.0 using Siemens industrial control configuration software. 2)
26、PLC programmable controller. Systems use Siemens SP - 300 - PLC programmable controller. Its modular structure, easy to implement distributed configuration and high cost performance, strong electromagnetic compatibility, resistance to shock impact performance is good, in a wide range of industrial c
27、ontrol field, become a kind of economical and practical solution. Variety of increasing performance of CPU and rich with many convenient features I/O extension module (including SM signal module, communication processor CP, IM interface module, etc.). The user can choose according to actual applicat
28、ion module. 3) the instrument equipment. In order to improve the anti-interference ability, type selection of instrument meter DDZ - IH 45 ma current output for 0123, to ensure the reliability of the system. Instrument include: flow transmitting, pressure transmitter, temperature transmitter, liquid
29、 level transmitter, micro oxygen transmitter, pressure transmitter, etc. 4) the frequency conversion control room. Mainly includes: power supply control cabinet, frequency conversion control cabinet, boiler circulating pump frequency conversion control cabinet, control cabinet is equipped with vario
30、us types of relay contactor, relay, etc., low voltage electrical equipment to complete the motor start and stop.2.3 the temperature control system software design2.3.1 PID instruction algorithm PID controller according to the error of the system parameter values, calculated by proportional integral
31、and differential control quantity to control, so called, PID control and PID control. In the field of industrial control, PID is still in wide use. Three kinds of control volume have different characteristics, separately to exist advantages and disadvantages are clearly, when used with various restr
32、ictions would have problems, how to adjust the PID parameter of the stability, becomes the current control of the most important step.2.3.2 characteristics of PID control algorithm 1) the proportion (P) control. Proportional (P) control is one of the most simple control method, the controller output
33、 to the input error signal is proportional to the relationship. Controller will happen if skewed, adjust the control output, the accused to reduce the amount of deviation in the direction of change. Deviation reduce speed determined by proportional coefficient Kp, Kp the faster, the greater the devi
34、ation decrease. But this will cause oscillation, especially in the hysteresis link is larger, the proportional coefficient Kp reduce the possibility of oscillation will be reduced, but at the same time can also lead to slow adjustment. Proportional control weakness is cant eliminate the steady-state
35、 error, integral control must be available to assist. 2) the integral (I) control. The output of the controller in the integral control is proportional to the input of the error signal integral relationship. After entering the steady state, if exist steady-state error control system, in order to eli
36、minate the steady-state error of the system, the integral item must be added. As time increases, the integral term will also increase, so even the relatively small error integral item will also be increased with the increase of time, it will further reduce the steady state, the existence of error to
37、 zero. So the proportional integral (PI) controller can make the system enter the steady-state no steady-state error. 3) differential (D) control. Under differential control, the controller output differential increases, the input error signal differential will also increase. The automatic control s
38、ystem for error control, there will be other unnecessary problems such as movements will more serious instability. That is to say, in the controller only introduced ratio is often not enough. Proportional action is only magnified error amplitude, but join differential item to avoid large errors. Bec
39、ause it can predict the direction of the error change, but the differential control can enlarge the high frequency noise, lower signal-to-noise ratio in the system, resulting in a decline in the ability of the system suppress interference. That is to say, differential control cant eliminate the resi
40、dual.2.3.3 PID parameter setting PID parameters setting is mainly to adjust P, Pi, Pt. To change the system characteristic and causing the system to achieve satisfaction index.2.3.4 PID algorithm program implementation In the SP - 300 - PID function is accomplished by PID instruction function block,
41、 by regularly perform PID function block. According to the PID operation rule, according to a given at the time, proportional integral differential data, calculate the control quantity.3 the PID program design Siemens PLC control program is to use the programming software S7V5. 3. First input analog
42、 signals, the boilers current voltage by numerical display. Second watch boiler the current temperature is normal, alarm indicator lamp whether can normal use. Initiator, observation after the start position, initialize the PID parameters, close the program, zero analog, continue to stop boiler heat
43、ing but still shows the temperature. Set temperature, the interrupt program, adjust PID parameter, output PID arithmetic as a result, the output analog signals.4 the configuration module design 1) Configuration software design. Select the configuration design of this system software is Siemens WINCC
44、 configuration software, WINCC is a powerful, has the very good open software. All kinds of complex task, WINCC can handle. WINCC belongs to man-machine interface configuration tool, its biggest characteristic is to system integration on the basis of the configuration. As long as the preset of vario
45、us software modules for simple configuration, you can easily implement each function of monitoring layer, shortens the time of system integration to improve the working efficiency. WINCC configuration software with Microsoft system as a platform, provide powerful editing functions, and itself contai
46、ns rich graphics resources, convenient design all kinds of industrial used figure, and easy to edit, at the same time with the computers versatility, reducing the workload. Users can design and editing function, make full use of the open sexual function. Because belong to Siemens, when using WINCC c
47、onfiguration software can easily to create S7-300 PLC in the system variables, edit and modify, greatly convenient for the user. 2) please communication up and down. Connect the PLC and the computer connection, after the completion of the set up communication in software. 3) the system debugging. Ag
48、ain and again, after the completion of up and down a machine connection adjust PID temperature control parameters, in order to get the optimal PID parameter values. Oscillation phenomenon occurring in a system, by adding differential adjustment, multiple optimal PID parameters resulting from the debug.5 conclusion This system adopts the single loop PID control, through many times to adjust PID parameter, get a quick response and high precision control of the boiler temperature control system, complete the intended target