CN100349076C - Control method of evaporation rate in Chinese medicine production concentration process - Google Patents

Abstract

The present invention discloses a method for controlling the evaporation rate in the process of the production and the concentration of traditional Chinese medicine. The present invention comprises the following procedures: the liquid level and the temperature of liquid medicine in one-effect evaporation room are detected by a liquid level sensor and a temperature sensor, and an actual value of the evaporation rate of the one-effect evaporation room is calculated; a setting value and the actual value of the evaporation rate are used as the input of a DMC controller, an inputting and setting value of a corresponding PID can be obtained by the control and the calculation of the DMC, and then, the inputting and setting value of the PID and the gas temperature in the one-effect room are together used as the input of the PID controller; thus, the controlling quantity of the valve opening of a steam regulating valve for a pipeline capable of controlling the evaporation rate is obtained. The present invention can accurately control the evaporation rate of liquid medicine in the process of the concentration of traditional Chinese medicine by utilizing the advantages of simple PID control, convenient parameter regulation, strong anti-high-frequency interference, good predictive control tracking performance and strong robustness, and is favorable to enhance the productive quality of traditional Chinese medicine.

Description

Chinese medicine is produced the control method of velocity of evaporation in the concentration process

Technical field

The present invention relates to a kind of Chinese medicine and produce the control method of velocity of evaporation in the concentration process.

Background technology

Along with the development of control technology, adopt advanced control system at the Chinese medicine production industry, improve science, accuracy that Chinese medicine is produced, more and more be subjected to the attention of Chinese medicine production manager.Because it is typical complex process control that Chinese medicine is produced the control of concentration section, needs the technological parameter of control to mainly contain temperature, pressure, velocity of evaporation, liquid level etc.In concentration process, exist between these parameters and influence each other, make that to set up precise math model infeasible, also make traditional pid control mode become inapplicable.Present stage, the Chinese medicine manufacturer of China generally was controlled to be the master with artificial experience in process of production, make each link of drug effect, composition and production of Chinese medicine not reach science, strict control, exist that control accuracy is low, labour intensity is big, inefficient shortcoming, seriously restricted the raising of the Chinese medicine quality of production.

Summary of the invention

The purpose of this invention is to provide a kind of Chinese medicine and produce the control method of velocity of evaporation in the concentration process.

For realizing above-mentioned purpose, the control method that this Chinese medicine is produced velocity of evaporation in the concentration process may further comprise the steps: utilize liquid level sensor to detect a soup liquid level of imitating in the vaporization chamber, and according to the velocity of evaporation in the vaporization chamber and in the unit interval linear relationship between the liquid level change amount calculate the velocity of evaporation actual value; With the input of velocity of evaporation setting value and actual value as the DMC controller, control is calculated and is obtained corresponding PID input setting value through DMC, again this PID input setting value and is imitated gas temperature in the vaporization chamber jointly as the input of PID controller, thereby obtain to control the pipeline steam regulating valve valve opening controlled quentity controlled variable of velocity of evaporation.

Above-mentioned Chinese medicine is produced in the control method of velocity of evaporation in the concentration process, and it is as follows that concrete steps are calculated in described DMC control:

Detect the actual output of velocity of evaporation, and the back of comparing with this moment velocity of evaporation predicted value constitutes the prediction output error of velocity of evaporation, this error and updating vector multiply each other as the velocity of evaporation error prediction, velocity of evaporation after model prediction obtains proofreading and correct prediction output again, and as new velocity of evaporation initial predicted value;

Following P velocity of evaporation desired output and velocity of evaporation initial predicted constantly exported the bias vector that constitutes, this bias vector carries out the control increment that dot product obtains this moment controlling object with dynamic control vector, control increment added up obtain PID control input value, this control increment and model vector multiply each other and calculate velocity of evaporation prediction output after its effect simultaneously, control vector is to utilize simulated program to determine the control coefrficient vector that the optimisation strategy of velocity of evaporation is calculated, the model coefficient vector that model vector obtains for the step response that detects generalized object and after smooth.

The present invention combines PID control and DMC PREDICTIVE CONTROL, utilize that PID control is simple, parameter adjustment is convenient, anti-high frequency interference is strong and PREDICTIVE CONTROL is applicable to Object with Time Delay, and it is good and model mismatch had advantage than strong robustness to have a tracking performance, can accurately control the velocity of evaporation of Chinese medicine concentration process herb liquid, help to improve the work efficiency of Chinese medicine concentration section.

The present invention is further illustrated with specific embodiment in conjunction with the accompanying drawings for following machine.

Description of drawings

The present invention is further described below in conjunction with accompanying drawing and example.

Fig. 1 is a control principle block diagram of the present invention.

Fig. 2 is the control synoptic diagram that Chinese medicine is produced concentration process.

Fig. 3 is DMC prediction-PID tandem control structure figure.

Fig. 4 is a DMC-PID tandem control algolithm block diagram.

Fig. 5 is predictive control algorithm realization flow figure.

Embodiment

Referring to Fig. 1, it is the heat and mass transfer process of a complexity that two effects concentrate.In concentration process, need the technological parameter of control to mainly contain temperature, pressure, velocity of evaporation, liquid level etc.Exist between these parameters and influence each other, exist between the temperature and pressure in the vaporization chamber and intercouple, temperature has a significant impact velocity of evaporation, and have direct linear relationship between the liquid level change amount in velocity of evaporation and the unit interval vaporization chamber, and the variation of the interior liquid level of vaporization chamber influences the variation of pressure again.Hence one can see that, and in concentration process, velocity of evaporation is a very important technical parameters, and the control of velocity of evaporation is also seemed particularly important.The present invention selects one to imitate the velocity of evaporation of vaporization chamber as final controlled target.The temperature of sensor acquisition, pressure, liquid level etc. are delivered to the DMC-PID controller, calculate back output controlled quentity controlled variable controlling plumbing fixtures steam regulating valve, reach the purpose of control velocity of evaporation through DMC-PID.

With reference to accompanying drawing 2, Fig. 2 is the industry spot synoptic diagram of in the concentration process velocity of evaporation being controlled.Wherein TT is a temperature transmitter; TC is a temperature controller, adopts PID control; LT is a fluid level transmitter; LC is a fluid level controller, adopts DMC control; In this algorithm structure, earlier get one and imitate in the vaporization chamber gas temperature, restraining variation of temperature in the 1st effective evaporator at any time, and regulated rapidly by the PID controller as middle controlled variable by temperature sensor.Again with this PID closed-loop system and 1st effective evaporator together as a generalized object, control with the DMC controller, this is the second layer of control.Compare with traditional PID tandem control, both are identical on interior ring, all adopt the PID regulator, and on outer shroud, the control of DMC prediction-PID tandem has replaced pid algorithm with the DMC algorithm.

Referring to Fig. 3, control procedure of the present invention: at first set velocity of evaporation setting value w, obtain level value by a liquid level sensor of imitating in the vaporization chamber simultaneously, and according to the velocity of evaporation in the vaporization chamber and in the unit interval linear relationship between the liquid level change amount calculate velocity of evaporation actual value y, with the input of above-mentioned velocity of evaporation setting value and actual value as the DMC controller, obtain corresponding PID input setting value through the DMC control algolithm. again this PID input setting value and one is imitated gas temperature T in the vaporization chamber jointly as the input of PID controller, thereby obtain to control the valve opening controlled quentity controlled variable of velocity of evaporation.Purpose according to hierarchical control, imitate the PID tandem control loop that gas temperature biography letter G2 (s) constitutes in the vaporization chamber by PID controller and among the figure and should comprise systematic main interference, and less pure hysteresis or time constant arranged, and adopt higher controlling of sampling frequency, the fundamental purpose of control is that in time suppressing one imitates the interference that gas temperature changes in the vaporization chamber.And the biography letter G1 (s) between the velocity of evaporation of gas temperature to the effect vaporization chamber in this a PID tandem control loop and the effect vaporization chamber is together as generalized object, adopt dynamic matrix control (DMC), realize good tracking and make system that robustness preferably be arranged when model mismatch.Because the DMC algorithm can be applicable to Object with Time Delay naturally, so, adopt the control of DMC prediction-PID tandem very effective for as two effects concentrate, having large time delay, strongly disturbing industrial object.

Be described in detail in the DMC-PID control algolithm of in the concentration technology process velocity of evaporation being controlled below in conjunction with accompanying drawing 4 and accompanying drawing 5:

The On-line Control algorithm structure of entire controller as shown in Figure 4.Among the figure, thick arrow representation vector stream, thin arrow is represented scalar stream.In each sampling instant, following P velocity of evaporation desired output ω constantly _p(k) with the output of velocity of evaporation initial predicted

The bias vector that constitutes is with dynamic control vector d ^TDot product obtains the control increment Δ u (k) of this moment to generalized object G (Z).This control increment is obtained controlled quentity controlled variable u (k) and is acted on generalized object G (Z) by accumulating operation on the one hand, multiplies each other with model vector a on the other hand and calculates velocity of evaporation prediction output after its effect To next sampling instant, at first detect the actual output y (K+1) of velocity of evaporation, and with this moment velocity of evaporation predicted value

The prediction output error e (K+1) of the back formation velocity of evaporation of comparing.This error and updating vector h multiply each other as the velocity of evaporation error prediction, again the prediction of the velocity of evaporation after model prediction obtains proofreading and correct output

The displacement back is as new velocity of evaporation initial predicted value Pass through the z among Fig. 3 again ^-1Link is defined as K constantly constantly new, and whole process is online repeatedly carries out.

The DMC-PID control algolithm of in the concentration technology process velocity of evaporation being controlled specifically comprises following several steps:

(1) generalized object chooses

In concentration process, velocity of evaporation is a very important technical parameters, and the control of velocity of evaporation is also seemed particularly important.This controller promptly selects one to imitate the velocity of evaporation of vaporization chamber as controlled target.In concentration section, to Temperature Influence in the 1st effective evaporator, therefore, adopt DMC prediction-PID tandem control structure when the main interference of system is discharged from condensate water, with gas temperature in the effect vaporization chamber as secondary object, i.e. G in the accompanying drawing 4 ₂(Z), reacting variation of temperature in the 1st effective evaporator at any time, and by the PID regulator H in the pid loop _c(Z) regulated rapidly, the selection principle of its parameter is with traditional PID regulator.And the DMC predictive control loop selects a velocity of evaporation of imitating vaporization chamber as controlled variable, and operating mode causes to overcome, the model mismatch that interior ring can't overcome again.The DMC predictive control loop is with PTD loop and main object, promptly one imitates gas temperature in the vaporization chamber and imitates biography letter G between the velocity of evaporation of vaporization chamber ₁(Z), as generalized object G (Z).

A) pid loop design

Pid loop selects a gas temperature of imitating vaporization chamber as controlled device, adopts traditional PID control strategy, realizes in slave computer.Because the sample frequency height, it is a kind of quasi-continuous control.The less secondary object G2 (s) of time lag for relative total system, PID control can obtain servo-actuated performance preferably, and the secondary interference to an effect vaporization chamber temperature that discharging causes to condensate water has good inhibitory effect.Pid parameter in the loop can adopt common engineering setting method, and is determined in conjunction with experimental formula.

Pass letter for the object in the pid loop, promptly the G2 (s) in the accompanying drawing 3 determines as follows:

Do not consider that one imitates coupling and the system disturbance between vaporization chamber room temperature θ, the pressure p, set up state equation after controlled device is oversimplified.Its state equation can be approximately: $\stackrel{.}{\mathrm{\θ}}+a_T\mathrm{\θ}=b_T{u}_T,$ In the formula

Be the rate of change of an effect vaporization chamber room temperature θ, u ₁It is the control action of an effect steam valve.Mainly change the evaporation indoor temperature in the concentration process by regulating this parameter.

This formula is carried out Laplace transform, and the mathematical model that obtains an effect vaporization chamber room temperature is:

$G_2\left(s\right)=\frac{K_2}{T_2+1}$

K ₂Be temperature static gain, T ₂It is temperature inertial element time constant.

B) DMC predictive control loop design

DMC PREDICTIVE CONTROL, this control are applicable to any asymptotically stable linear object in principle.At this moment, need at first measure the step response of generalized object G (Z), then as requested, take method of trial and error, the DMC design parameter of DMC predictive control loop is adjusted.Concentrate this typical industrial process for two effects, controlled device has the typical characteristics that inertia adds pure hysteresis.Because the main object in the DMC predictive control loop, i.e. G in the accompanying drawing 3 ₁(S) the main time lag and the large time constant part that have comprised system in.Can be similar to and think that it has following form:

$G_1\left(S\right)=\frac{K_1{e}^{-\mathrm{\τS}}}{T_{1}s+1}$

(2) foundation of generalized object forecast model

Because the DMC algorithm is a kind of control based on model in the controller, and used the on-line optimization technology, compared with traditional control algolithm, it needs more off-line preliminary work to determine controller parameter, realization flow as shown in Figure 4, this mainly comprises following several respects:

A) detect the step response of generalized object and after smooth, obtain model coefficient a ₁..., a _NFor the 1st effective evaporator that will control, the dynamic response of model must be smooth, measures noise and disturbs necessary filtering, otherwise can influence control of quality even cause instability.

B) utilize simulated program to determine the optimisation strategy of velocity of evaporation, calculate control coefrficient d ₁..., d _p

C) select velocity of evaporation forecast model correction coefficient h ₁..., h _N

After these three groups of performance coeffcient are determined, insert the internal storage location of concentration section supervisory controller, get final product real-time calling.

(3) rolling optimization and feedback compensation

The forming by initialization module and real-time control module of DMC in the controller in line computation, as shown in Figure 5.Initialization module is the actual output y (k) that detects velocity of evaporation in the first step that puts into operation, and it is set at velocity of evaporation prediction initial value

I=1 ..., N.Promptly change real-time control module over to from second step, at the visible accompanying drawing 5 of the online calculation process of each sampling instant, wherein to the velocity of evaporation predicted value of exporting future a N dimension group y (i) only need be set, the formula in the process flow diagram is successively corresponding to following formula:

$e(k+1)=y(k+1)-{\tilde{y}}_1(k+1|k)$

${\tilde{y}}_{\mathrm{cor}}(k+1)={\tilde{y}}_{N1}\left(k\right)+\mathrm{he}(k+1)$

${\tilde{y}}_{N0}(k+1)=S{\tilde{y}}_{\mathrm{cor}}(k+1)$

${\tilde{y}}_{N1}\left(k\right)={\tilde{y}}_{N0}\left(k\right)+\mathrm{a\Δu}\left(k\right)$

In accompanying drawing 5, velocity of evaporation setting value w is definite value and inserts internal memory in advance.If the path that the velocity of evaporation setting value becomes need be set to the time can be worked out a setting value module, with at each velocity of evaporation expectation value w (i) constantly of line computation, i=1 ..., P, and replace w in the process flow diagram with this.

Claims (2)

1, a kind of Chinese medicine is produced the control method of velocity of evaporation in the concentration process, may further comprise the steps:

Utilize liquid level sensor to detect a soup liquid level of imitating in the vaporization chamber, and according to the velocity of evaporation in the vaporization chamber and in the unit interval linear relationship between the liquid level change amount calculate the velocity of evaporation actual value;

With the input of velocity of evaporation setting value and actual value as the DMC controller, control is calculated and is obtained corresponding PID control input value through DMC, again with it and one imitate gas temperature in the vaporization chamber, thereby obtain the pipeline steam regulating valve valve opening controlled quentity controlled variable of control velocity of evaporation jointly as the input of PID controller.

2, Chinese medicine according to claim 1 is produced the velocity of evaporation control method of concentration process, it is characterized in that: it is as follows that concrete steps are calculated in described DMC control:

Detect the actual output of velocity of evaporation, and the back of comparing with this moment velocity of evaporation predicted value constitutes the prediction output error of velocity of evaporation, this error and updating vector multiply each other as the velocity of evaporation error prediction, velocity of evaporation after model prediction obtains proofreading and correct prediction output again, and as new velocity of evaporation initial predicted value;

Following P velocity of evaporation desired output and velocity of evaporation initial predicted constantly exported the bias vector that constitutes, this bias vector carries out the control increment that dot product obtains this moment controlling object with dynamic control vector, control increment added up obtain PID control input value, this control increment and model vector multiply each other and calculate velocity of evaporation prediction output after its effect simultaneously, control vector is to utilize simulated program to determine the control coefrficient vector that the optimisation strategy of velocity of evaporation is calculated, the model coefficient vector that model vector obtains for the step response that detects generalized object and after smooth.

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