重庆大学过程控制processcontrol中文翻译学习课件

1Process Control systems2Practical Issues of Process ControlOutline:Digital Control 数字控制 Progress in在有进展 Process Control Sampling the measurement测量采样 Digital PID calculation and execution performance 数字PID计算和执行的性能 Make PID work（in practice在实践中）Select proper field instrumentation选择适当量程的仪表 Validate 验证and correct 调整measurements测量值 Use&tune various industrial PID algorithms使用&调整各种工业PID算法 Improve performance of“simple”PID 提高简单PID的性能3Practical Issues of Process ControlDigital Control:Progress in Process Control The（steam engine蒸汽机）works all the time control the（boiler pressure 锅炉压力）the speed of the device设备的速度 People experienced人们靠经验控制 Explosions 易爆炸 unstable behavior 不稳定 Control engineering控制工程 was born4Practical Issues of Process ControlDigital Control:Progress in Process Control控制领域的进步 Manual 手工的Mechanical 机械的devicesPneumatic气动的 devicesElectronic 电子的devicesDigital calculation数字计算Digital calc.&communication通信5Practical Issues of Process ControlDigital Control:Progress in Process Control Manual Mechanical devicesPneumatic devicesElectronic devicesDigital calculationDigital calc.&communication6Practical Issues of Process ControlDigital Control:Progress in Process Control Manual Mechanical devicesPneumatic devicesElectronic devicesDigital calculationDigital calc.&communication7Practical Issues of Process ControlDigital Control:Progress in Process Control Manual Mechanical devicesPneumatic devicesElectronic devicesDigital calculationDigital calc.&communicationP(t)8Pneumatic Practical Issues of Process ControlDigital Control:Progress in Process Control Manual Mechanical devicesPneumatic devicesElectronic devicesDigital calculationDigital calc.&communication9ElectronicSimplified Diagram of Taylor transcope electronic controllerPractical Issues of Process ControlDigital Control:Progress in Process Control Manual Mechanical devicesPneumatic devicesElectronic devicesDigital calculationDigital calc.&communication10Practical Issues of Process ControlDigital Control:Progress in Process Control Manual Mechanical devicesPneumatic devicesElectronic devicesDigital calculationDigital calc.&communicationElectronic Device电子设备11Practical Issues of Process ControlDigital Control:Progress in Process Control Manual Mechanical devicesPneumatic devicesElectronic devicesDigital calculationDigital calc.&communicationDigital Calculation for Electronic Device电子设备的数字计算12Practical Issues of Process ControlDigital Control:Progress in Process Control Manual Mechanical devicesPneumatic devicesElectronic devicesDigital calculationDigital calc.&communicationDigital Calculation and Communicationtransmission by local network 通过本地网络传递sensor and valve have microprocessor微处理器13Practical Issues of Process ControlDigital Control:Progress in Process Control Distributed computing network分布式计算网络14Practical Issues of Process ControlDigital Control:Progress in Process Control Distributed computing network15Practical Issues of Process ControlDigital Control:Progress in Process Control A rough indication of the progress in大致方面的进步在 process control16Practical Issues of Process ControlDigital Control:Progress in Process Control Manual Mechanical devicesPneumatic devicesElectronic devicesDigital calculationDigital calc.&communicationApplicable for适用于 digital sampling采样 and calculation计算 Transmission can be electronic or digital.传输可以电子的或数字的 Measurement is periodically sampled for calcution测量是定期的采样和计算17Practical Issues of Process ControlDigital Control:Sampling Times采样时间 The control loop控制回路 sample time how often controller samples the process variable(PV)采样频率 compute&transmit传输 a new controller output(p)signal The p-PV rate,at whichp-PV data are sampled and recorded during a bump test颠簸试验18Practical Issues of Process ControlDigital Control:Sampling Times Sampling too slow:negative impact on performance负面响应 Aliasing欠采样:Sampling much slower than the measurement changes causes significant loss of information.采样比测量慢得多会造成重大损失的信息Sampling slow19Practical Issues of Process ControlDigital Control:Sampling Times Sampling too slow:negative impact on performance Aliasing:Sampling much slower than the measurement changes causes significant loss of information Zero-order hold零阶保持器零阶保持器20Practical Issues of Process ControlDigital Control:Sampling Times Sampling too slow:negative impact on performance Introducing介绍 dead-time Td=T/221Practical Issues of Process ControlDigital Control:Sampling Times Sampling too fast （not necessarily不一定）provide better performance性能,spend more than necessary on high-end高端 instrumentation 仪表 spend more computing resources计算资源22Practical Issues of Process ControlDigital Control:Sampling Times“Fast and slow”Being defined by the process time constant定义过程时间常数,How to choose sampling time,tBest Practice 1:Sample time should be 10 times per process time constant or faster采样时间应是每个过程时间常数的10倍或更快,i.e.,t 0.1 This rule applies for应用于 both control loop sample time and bump test data collection颠簸试验数据采集are the same23Practical Issues of Process ControlDigital Control:Sampling Times“Fast and slow”Being defined by the process dead time constant,Td How to choose sampling time,tBest Practice 2:Sample time should be 0.8 times per dead time constant or faster,i.e.,t 0.8Td This rule applies for both control loop sample time and bump test data collection are the same24Practical Issues of Process ControlDigital Control:The digital P-I-D Controllers Suppose sample data,PV1,PV2,PVi,controller output p(i),p(i)is the deviation偏差 variable)()(:Control-PiEKipPVSPE(i)cii)()()()1()(and :Control-IiEtKipiEiEiEPVSPE(i)sumIcsumsumiitPVPVKipiiDc1)(:Control-D25Practical Issues of Process ControlDigital Control:The digital P-I-D Controllers The position form of the digital PID 数字PID位置表 The continuous position连续位置 PIDdttdPVdttEtEKtpDtIc)()(1)()(0tPVPVtnEiEKipiiDinIc11)(1)()(pThe discrete(digital)position离散位置 PID26Practical Issues of Process ControlDigital Control:The digital P-I-D Controllers The velocity form of速度形式的 the digital PID Calculate计算 the signal change at the i th execution在第i个执行tPVPVPVtiEiEiEKipiiiDIc212)(1)1()()(pCalculate then the control signal at the i th executionp计算第i个执行的控制信号，)()1()(ipipip27Practical Issues of Process ControlDigital Control:The digital PID Performance What is the effect of digital PID controller数字PID控制器的影响是什么How about the digital PID controllerSPContinuous SettingsKc=30,I=11 min,D=0.8 mintPVPVtnEiEKipiiDinIc1)(1)()(28Practical Issues of Process ControlDigital Control:The digital PID Performance效果 Comparison between continuous and discrete PID Continuous PID K=0.039%A%Open =10.5 Td=5.5 Kc=30,I=11 min,D=0.8 minIAE=12.2Discrete(Digital)PID K=0.039%A%Open =10.5 Td=5.5+T/2=5.5+5/2=7.5 Kc=30,I=11 min,D=0.8 minIAE=20.038329Practical Issues of Process ControlDigital Control:The digital PID Performance Comparison between continuous and discrete PID pConclusion:Things dont get better by slowing the loop!p事情并没有得到更好效果在 采样频率的回路中pWhy do we convert the real-world control to digital?30Practical Issues of Process ControlDigital Control:The digital PID Performance Improve改善 the discrete(digital)PID Td=t/2n recall that sampling introduces a dead time回忆，采样 引入了一个延迟时间 n Semi-Digital半数字化 PID说明：obtain获得，empirical 经验的，recalculate重新计算，implement and fine tune as needed根据需要实现和微调31Practical Issues of Process ControlDigital Control:Improve the discrete(digital)PID Td=t/2n recall that sampling introduces引入 a dead time Best Practice 3:Sample time should follow the below due to dead time采样时间应遵循以下，由于延迟时间 t 0.05(+Td).It also applies for both control loop sample time and bump test data collection are the same32Practical Issues of Process ControlDigital Control:Improve the discrete(digital)PID Td=t/2n recall that sampling introduces a dead time Best Practice 4:Typical sample period for chemical process化工工艺 control is 0.25-0.50 second.Much faster is possible,if needed.33Practical Issues of Process ControlDigital Control:Why Digital Control?Calculations and display：计算和显示34Practical Issues of Process ControlDigital Control:Why Digital Control pConquering获取 the complex复杂的 controllerOne way to Improve performance增强效果 p（Being achieved with实现）algorithms算法 that optimize优化 the path to路径 the set point,every controller execution执行力!35Practical Issues of Process ControlDigital Control:Why Digital Control Optimizing the process优化过程36Practical Issues of Process ControlDigital Control:Why Digital Control Monitoring the process监控过程Using a digital history of measurements测量历史 forn Recall at any time for trouble shooting故障检修n Calculation of process 计算过程 performance indicators性能指标,heat transfer coefficients传热系数,reactor yields反应堆收益率 energy/kg of product产品能量/每公斤,n Graphical displays图形显示 with data in context of process schematic原理图37Practical Issues of Process ControlMaking PID Work in Practice-Issues实践问题 Select proper field instrumentation正确量程仪表 Validate and correct measurements(noise reducing)验证和调整测量值(噪音减少）Use&tune various industrial PID algorithms 使用&调整各种工业PID算法 Improve performance性能 of“simple”PID38Practical Issues of Process ControlMaking PID Work in Practice-Issues Four Aspects方面 of the practical issuesEnhance the simple PID for shortcoming缺点 Account for说明的原因39Practical Issues of Process ControlMaking PID Work in Practice-Issues The feedback loop:Issues Considered 反馈回路的问题40Practical Issues of Process ControlMaking PID Work in Practice-Issues The feedback loop:Wire-in&Wire-out Perspective进线盒出现透视图41Practical Issues of Process ControlMaking PID Work in Practice-Issues Selection of proper sensor(transducer传感器)Sensor range 1.The values over which the sensor can record the PVs该传感器可以记录的PV值2.We need to“cover”expected预期的 range,3.the sensor accuracy精度 decreases as the range increases The range for common PVs in process control过程控制常见的pv范围(a)Temperature:oC,the normal operating工作 range(b)Flow:L/s,from 0.0 to the maximum expected flow(c)Pressure:PSI,the normal operating range(d)Level:0-100%(not meters,dont have to memorize the height of every vessel)42Practical Issues of Process ControlMaking PID Work in Practice-Issues Selection of proper sensor(transducer)A distilling tower一个蒸馏塔43Practical Issues of Process ControlMaking PID Work in Practice-Issues Reduction of noisePIDFilter：过滤器44Practical Issues of Process ControlMaking PID Work in Practice-Issues Reduction of降低 noise我们认为噪声是不可重复的测量成分原因：电气干扰,不完美的混合,动荡Is seldom as很少作为clear-cut明确As shown here如上所示45Practical Issues of Process ControlMaking PID Work in Practice-Issues Reduction of noiseTypical Value in Chemical Processescontrollable可控制的our plants are relatively slow我们的工厂相对较慢46Practical Issues of Process ControlMaking PID Work in Practice-Issues Reduction of noiseanalog filter模拟滤波器around and around绕着47Practical Issues of Process ControlMaking PID Work in Practice-Issues Reduction of noiseConclude about the favorable filter dynamics总结 有利于增强滤波强度48Practical Issues of Process ControlMaking PID Work in Practice-Issues Reduction of noiseamplitude ratio幅值比how would the perfect filter behave完美的过滤器将如何表现phase angle相位角49Practical Issues of Process ControlMaking PID Work in Practice-Issues Reduction of noisewe have only a rough estimate of this boundary anyway我们只有的粗略估计这个边界50Practical Issues of Process ControlMaking PID Work in Practice-Issues Reduction of noise51Practical Issues of Process ControlMaking PID Work in Practice-Issues Reduction of noiseanti-aliasing反锯齿few tenths of a second零点几秒的时间52Practical Issues of Process ControlMaking PID Work in Practice-Issues Reduction of noiseBest Practice 5:(a)Reduce the derivative time微分时间(often to 0.0)(b)Set filter time constant small w.r.t.feedback dynamics f2 0.05(+)(c)Set filter time constant large w.r.t disturbance frequency扰动频率,f2 5/n,but do not violate b above.不违背bTo reduce the effects of noise on feedback,we have53Practical Issues of Process ControlMaking PID Work in Practice-Issues Determine确定 the PID parameters for commercial systems Recall that the PID controllers in different form)()1()(2)(1)1()()(:formVelocity)(1)()(:formPosition2111ipipiptPVPVPVtiEiEiEKiptPVPVtnEiEKipiiiDIciiDinIcdttdPVdttEtEKtpDtIc)()(1)()(:PIDContinuous0Velocity 速率54Practical Issues of Process ControlMaking PID Work in Practice-Issues The feedback control of P,I and D elementsCheck your(vendors供应商的)PID error（notation符号）Convention 约定55Practical Issues of Process ControlMaking PID Work in Practice-Issues The feedback control of P,I and D elementsPBscpPVcscKKKrangerange100.or,formulated with制定engineering units工程单位56Practical Issues of Process ControlMaking PID Work in Practice-Issues The feedback control of P,I and D elementsdttdPVdttEtEKKtpDtIcsense)()(1)()(057Practical Issues of Process ControlMaking PID Work in Practice-Issues The feedback control of P,I and D elementsdttdPVdttEtEKKtpDtRcsense)()()()(0.input must engineer thesoftware,some In Time.Reset theis This ,1RIRReset time复位时间58Practical Issues of Process ControlMaking PID Work in Practice-Issues The feedback control of P,I and D elementsdttdPVdttEtEKKtpDtRcsense)()()()(0With reset windupWithout reset windupreset windup重置饱和59Practical Issues of Process ControlMaking PID Work in Practice-Issues The feedback control of P,I and D elementsAnti-Reset-Windup抗复位饱和:Combination of Jacketing套 Rule and Velocity速率 Formminmax21)()()()1()(2)(1)1()()(:formVelocitypippipipipiptPVPVPVtiEiEiEKipiiiDIcJacketing rule for anti-reset-windup反复位饱的护套规则60Practical Issues of Process ControlMaking PID Work in Practice-Issues The feedback control of P,I and D elementsDerivative Filter微分滤波 If we filter the measurement,we“slow”all controller modes.An option exists to存在 filter only the derivative mode.dttdPVdttEtEKtpDtIc)()(1)()(011DDssImplement实现 the derivative element微分环节 as in the left =0.1,giving a filter of 10%of the derivative time 给一个0.1倍微分时间的滤波器 Usually =0.05-0.2(see lecture_05-I)61Practical Issues of Process ControlMaking PID Work in Practice-Issues Improve PID performance:the controller outputBumpless transfer无干扰切换 when the controller is switched from manual 人工的(off)to automatic(on),the final element(valve)should start from its initial value初始值How to reach the bumpless transfer effect效果 set the controller output to the default缺省的 actuator(valve)value set the controller output to the current output value62Practical Issues of Process ControlMaking PID Work in Practice-Issues The controllers output is set to the current valve endiftPVPVPVtiEiEiEKipPVSPiEiEiEelsePVPVPVSPiEipipiiiiDIciiiiii2112)(1)1()()()()()1()(0)(element final theouput tocurrent)(,1 if63Practical Issues of Process ControlMaking PID Work in Practice-Issues The controllers output is set to current value minmax112)()1()(controller theofpart normal/PVPVPVPVPVPVPVPVipipipiiiiiinExample:select the controller initial value初始值 for a distilling tower蒸馏塔 shown in the next slide幻灯片64Practical Issues of Process ControlMaking PID Work in Practice-Issues The controllers output is set to current value Failure故障65Practical Issues of Process ControlMaking PID Work in Practice-Issues The controllers output is set to current value 66Practical Issues of Process ControlMaking PID Work in Practice-Issues The controllers output is set to current value flexible diaphragm柔性膜片67Practical Issues of Process ControlMaking PID Work in Practice-Issues A case study:the analysis for sample timeThree-tank concentration浓度 PI-control)0.2(0.2)()(0.27)(0.200)(0.3842233tutydttdydttyddttydSPsolvent 溶剂pure纯的68Practical Issues of Process ControlMaking PID Work in Practice-Issues A case study:the analysis for sample time69Practical Issues of Process ControlMaking PID Work in Practice-Issues A case study:the analysis for sample timeSolution:(1)The process is approximated by a FOPT modelwhere Kp=2.0 process gain (how far),=20 time constant (how fast),td=9.8 dead time (how much delay),1)(seKsGstppd70Practical Issues of Process ControlMaking PID Work in Practice-Issues A case study:the analysis for sample timeSolution:(2)choose PI controller for this FOPT processsksEsPsGsIcc11)()()(:form domaintIcdttetektp0)(1)()(:form domain timeTime domain form 时域形式71Practical Issues of Process ControlMaking PID Work in Practice-Issues A case study:the analysis for sample timeSolution:(3)determine the Kc and I by direct synthesis直接融合8478.9802010max8010max20570)84.78.9(0.220)(.,.t.,.ttkKdcIcdpc :where have we 6.2,table from72Practical Issues of Process ControlMaking PID Work in Practice-Issues A case study案例研究:the analysis for sample timeSolution:(4)sampling the data（with the best和一样好）practice 1Other choice for sampling timepractice 2,or your creative ideas你的创意PID designing is an art more than science0.2201.01.01.0maxtt 73Practical Issues of Process ControlMaking PID Work in Practice-Issues A case study:the analysis for sample timeSolution:(5)Initialize初始化 the parameters of the system (5a)normalize标准化 the system parametersBest Practice 6:The parameters can be normalized by your choice规范化的参数可以由你自己决定rangescaledrangescaledrangescaledPVEE PVPVPVPVpppp ,minmin74Practical Issues of Process ControlMaking PID Work in Practice-Issues A case study:the analysis for sample timeSolution:(5)Initialize the parameters of the system (5b)initialize the（system variable环境变量）Best Practice 7:Arbitrarily任意的 initialize the follows at 50%controller output:p (controlled variable CO)process variable:PV (controlled variable CV)set point:SPdisturbance D75Practical Issues of Process ControlMaking PID Work in Practice-Issues A case study:the analysis for sample timeSolution:(5)Initialize the parameters of the system (5c)the system parameters are initialized as in 该系统的参数进行了初始化controller output:pprocess variable:PV=2.2 ppm with range of 2.0,2.4set point:SP=2.2 ppm with range of 2.0,2.4disturbance D =2.0 L/min with occasional偶然的 spikes up to峰值达到 5.076Practical Issues of Process ControlMaking PID Work in Practice-Issues A case study:the analysis for sample timeSolution:(6)bump test颠簸试验for the process,that is,using the FOPDT mode to approximate the Original最初的 three-order process with dead time)10.3)(10.8)(116(02)()()()0.2(0.2)()(0.27)(0.200)(0.3840.22233ssse.sPsPVsGtptPVdttdPVdttPVddttPVdsp:form domain-s:form domain time1)(seKsGstppd77Practical Issues of Process ControlMaking PID Work in Practice-Issues A case study:the analysis for sample timeSolution:(6)bump test for the process1)(seKsGstppd)10.3)(10.8)(116(02)()()(0.2ssse.sPsPVsGspBump the process with step function阶跃函数 P(s)=A/sBest Practice 8 the size of step function,A,usually take the value over the interval 区间of 0.4,1.2 while the PV is normalized标准化 to 0,1 78Practical Issues of Process ControlMaking PID Work in Practice-Issues A case study:the analysis for sample timeSolution:(6a)bump test for the process-step function sizeThe size of 大小step functionA=1.279Practical Issues of Process ControlMaking PID Work in Practice-Issues A case study:the analysis for sample timeSolution:(6a)bump test for the process:step function sizeThe size of step is around大约 50%of the p A=0.5280Practical Issues of Process ControlMaking PID Work in Practice-Issues A case study:the analysis for sample timeSolution:(6b)Impact of影响 Loop Sample Time with PI controllerPI controller with fast sample time has modest impact on performance性能81Practical Issues of Process ControlMaking PID Work in Practice-Issues A case study:the analysis for sample timeSolution:(6b)Impact of Loop Sample Time with PI controllerPI controller with slow sample time degrades the performance82Practical Issues of Process ControlMaking PID Work in Practice-Issues A case study:the analysis for sample timeSolution:(6c)Impact of Data Collection Sample TimeData collection数据采集 with fast sample time provides “faster is better”performance83Practical Issues of Process ControlMaking PID Work in Practice-Issues A case study:the analysis for sample timeSolution:(6c)Impact of Data Collection Sample TimeData collection with“best practice 1”rule gives acceptable performance84Practical Issues of Process ControlMaking PID Work in Practice-Issues A case study:the analysis for sample timeSolution:(6c)Impact of Data Collection Sample TimeData collection withSlow sample time gives unacceptable p