重庆大学过程控制processcontrol中文翻译1.pptx

《重庆大学过程控制processcontrol中文翻译1.pptx》由会员分享，可在线阅读，更多相关《重庆大学过程控制processcontrol中文翻译1.pptx（32页珍藏版）》请在淘文阁 - 分享文档赚钱的网站上搜索。

1、1Analysis of Single Loop SystemsOutlinePID ControllersP-controller,PI controller,PD controller,PID controllerA General SISO System 一般的单输入单输出系统Transfer function with process model 过程模型的传递函数Signal transmitter信号变送器ControllerActuator(control valves)执行器(控制阀)Closed-Loop Response闭环响应Seven examplesChoice of

2、 controllers第1页/共32页2Analysis of Single Loop SystemsPID ControllersAn exampleMonitoring the liquid leve in a vesselAdjusting the opening of the affluent valve监测容器液体高度，调整阀门开度Keeping the liquid level at some user specified value(set point,or reference)The liquid level is both the measured and controll

3、ed variable液位是测量与控制的两个变量(they are the same in SISO system)第2页/共32页3Analysis of Single Loop SystemsPID ControllersAn exampleObjective（目的）:Keeping h at hs 维持h在hsSituation:A sudden surge at the inlet flow qi increases h在入口流量qi骤增增重h Deviation（偏差）:Resulting in（导致）h=h-hs0Rectification（矫正）:Opening up the v

4、alve (lowering the flow resistance R):开放的阀门(降低流动阻力R)Control:The signal of the controller,p(t)is the function of the deviation variable h 控制型号p(t)是偏差变量h 的函数第3页/共32页4Analysis of Single Loop SystemsPID ControllersAn exampleDefining an error signal due to the use of negative feedback由于负反馈的使用定义一个误差信号e(t)

5、=hs(t)-h(t)The actual control output 实际控制输出ps is the actuating signal（预处理信号）at steady state(i.e.,h=0),called the controller bias signal 被称为控制器偏差信号第4页/共32页5Analysis of Single Loop SystemsPID ControllersProportional control（比例控制）(P-control):Proportional ModeThe compensation（补偿）signal(actual controller

6、 output)is proportional to（与.成比例）the error（误差）,e(t)where Kc is the proportional gain of the controller,determing the controller sensitivity（灵敏度）第5页/共32页6Analysis of Single Loop SystemsPID ControllersP-controlAll commercial devices（商业设备）has positive gainThe controller output moves in the reverse dire

7、ction of the controlled variable控制器的输出向控制变量的反向变化第6页/共32页7Analysis of Single Loop SystemsPID ControllersP-controlIn the liquid level problem液位平衡问题,if the disturbation in the inlet makes h rise over h,thuse 0 p psThe controller output is decreasedPurchasing a vlave where a lowered signal means opening

8、 the valve降低的信号，意味着打开阀门 with the negative steady state gain(-Kv)The controller is written as e(t)=hs(t)-h(t)第7页/共32页8Analysis of Single Loop SystemsPID ControllersP-controlThe error is es=0 at t=0 The deviation variable is defined as e(t)=e(t)-esTransfer functionThe percent proportional band(PB)e(t)

9、=hs(t)-h(t)第8页/共32页9Analysis of Single Loop SystemsPID ControllersP-control:S-DomainTime-Domain第9页/共32页10Analysis of Single Loop SystemsPID ControllersP-control:第10页/共32页11Analysis of Single Loop SystemsPID ControllersP-control:Modern Level Sensor现代液位传感器第11页/共32页12Analysis of Single Loop SystemsPID

10、Controllers:P-control:第12页/共32页13Analysis of Single Loop SystemsPID ControllersIn the sense（传感器）of proportional gain KcThe higher gain,the faster(less stable)controlKc 越大，响应速度快越不稳定.The lower gain,the slower(more stable)control.Kc 越小，响应速度慢越稳定.第13页/共32页14Analysis of Single Loop SystemsPID ControllersF

11、rom practical perspective,define a new quantity从实际应用的角度,定义一个新的量The Proportional Band(PB)（比例范围）is the inverse of the Gain.负增益In the sense of proportional band PBThe higher PB,the slower(and more stable)control.越高的PB，越慢越稳定的控制The lower PB,the faster(and less stable)control.第14页/共32页15Analysis of Single

12、 Loop SystemsPID ControllersThe Percent Proportional Band百分比例带From Practical perspective:第15页/共32页16Analysis of Single Loop SystemsPID ControllersQualitative features of p-control P控制器的定性特点A p-controller accelerates（加速）the response of a processThe larger Kc,the faster is the change to a given error误

13、差Too large Kc will make the process unstableThe control system is saturated at the physical limits该控制系统是饱和的物理极限Controller can only deliver（传送）so much voltage or current（电压和电流）A valve can only deliver so much fluid when fully opened阀门完全打开只能提供了这么多流体第16页/共32页17Analysis of Single Loop SystemsPID Control

14、lersProportional-integral(PI)control:Persistent ModeAccumulating（累积）the historical errors（误差）(integral action)Eliminating the offset(steady state error)消除静差（稳态误差）where I is the integral time constant(reset time)1/I is called the reset rate,used in commercial devices1/I被称为复位率，商用设备中使用 第17页/共32页18Analy

15、sis of Single Loop SystemsPID ControllersProportional-integral(PI)controlController Behaviour when e(t)is constant Slope=E/ITime DomainS-DomainWhat is the difference Compared with P-control第18页/共32页19Analysis of Single Loop SystemsPID Controllers:PI control1.The integral action may overcompensate（过度

16、补偿）(oscillation振荡),thus exhibiting the underdamped response因此展示了过阻尼响应2.In practice,integral action is never used by itself不单独应用3.Integral action makes the process saturation（饱和）,reset windup（积分饱和）Integral term takes on a final nonzero value,thus Permitting（允许）es to stay at zero,as time progresses第19

17、页/共32页20Analysis of Single Loop SystemsPID Controllers:PI controlReset windup:the reset element of the controller continues to increase(or decrease)the controller output控制器的复位元素继续增加（或减少）控制器的输出even when the change in output does not cause any change in the process measurement(controlled variable).即使在

18、输出的变化不会引发任何过程中测量改变(控制变量)。with no resulting（致使）decrease in error（没有导致误差减少）,the output will continue to increase until it reaches its limit.第20页/共32页21Analysis of Single Loop SystemsPID Controllers:PI controlFrom practical perspective,avoiding reset windup（积分饱和）The integral of the errors对误差积分第21页/共32页

19、22Analysis of Single Loop SystemsPID Controllers:PI controlFrom practical perspective,avoiding reset windupWindup vs.Anti-Windup第22页/共32页23PID ControllersGeneral qualitative（定性的）features of PI control From Practical Perspective（实践角度）Using PI controller when offset（补偿）is unacceptably bigOffset elimin

20、ation（偏移消除）results a more underdamped process（过阻尼过程）Lowering the proportional gain Kc while integral used当运用积分控制器时降低比例增益的作用Analysis of Single Loop Systems第23页/共32页24Analysis of Single Loop SystemsPID ControllersProportional derivative（微分）(PD)control:Predictive Mode预测模型Derivative action（微分作用）is based

21、 on how fast the error is changing with time 误差变化率where D is the derivative time constant(or,rate time)The controller outputs zero as long as the error stays constantA small change in error may produce（产生）a big controller outputoccurring in changing set point(derivative kick)exhibiting in high-frenq

22、uency noise 产生高频噪声第24页/共32页25Analysis of Single Loop SystemsPID ControllersProportional derivative(PD)controlDerivative action is never used by itself微分作用不单独应用Commercial PD controllers are designed by lead-lag elementswhere is a small number,typically（代表的）0.05 t)Proportional ModeP-ControlPersistent

23、ModeI-ControlPredictive ModeD-ControlHistorical periodCurrent TimeFuture Time第29页/共32页30Analysis of Single Loop SystemsPID ControllersPuting all together PID controlt-domains-domain第30页/共32页31Analysis of Single Loop SystemsPID ControllersImplementation（实现）of PID controllerUsing lead-lag element（？）for the derivative（微分）controlIntroducing（引入）the derivative control in series with PI controlBeing referred to as interacting PID,series PID,orrate-before reset PIDAny other implementation?第31页/共32页32谢谢您的观看！第32页/共32页