CN107168065A - A kind of control method and system for selective catalytic reduction denitration device - Google Patents
A kind of control method and system for selective catalytic reduction denitration device Download PDFInfo
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- CN107168065A CN107168065A CN201710470971.6A CN201710470971A CN107168065A CN 107168065 A CN107168065 A CN 107168065A CN 201710470971 A CN201710470971 A CN 201710470971A CN 107168065 A CN107168065 A CN 107168065A
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B13/00—Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion
- G05B13/02—Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion electric
- G05B13/04—Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion electric involving the use of models or simulators
- G05B13/042—Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion electric involving the use of models or simulators in which a parameter or coefficient is automatically adjusted to optimise the performance
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/86—Catalytic processes
- B01D53/8621—Removing nitrogen compounds
- B01D53/8625—Nitrogen oxides
- B01D53/8631—Processes characterised by a specific device
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/86—Catalytic processes
- B01D53/90—Injecting reactants
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2251/00—Reactants
- B01D2251/20—Reductants
- B01D2251/206—Ammonium compounds
- B01D2251/2062—Ammonia
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2258/00—Sources of waste gases
- B01D2258/02—Other waste gases
- B01D2258/0283—Flue gases
Abstract
The present invention discloses a kind of control method and system for selective catalytic reduction denitration device, and control method includes：Set up the Simulation Experimental Platform of selective-catalytic-reduction denitrified system；According to each given first entrance oxynitride concentration and first outlet oxynitride concentration operation Simulation Experimental Platform, corresponding first ammonia spraying amount is obtained；Using the multigroup off-line data of hard measurement analytical, spray ammonia control system model is obtained, wherein, each group off-line data includes：First entrance oxynitride concentration, first outlet oxynitride concentration and corresponding first ammonia spraying amount；Bilinear transformation is carried out to spray ammonia control system model using model predictive control method, the predictive control model for controlling ammonia spraying amount is obtained.The predictive control model that the present invention is obtained can adjust corresponding ammonia spraying amount in real time according to the outlet oxynitride concentration of setting and the entrance oxynitride concentration of prediction, and the escape amount of ammonia can also be reduced while denitration efficiency is improved.
Description
Technical field
The present invention relates to denitration field, more particularly to a kind of control method for selective catalytic reduction denitration device
And system.
Background technology
With the fast development of shipping business, nitrogen oxides (the nitric oxide of global marine vessel discharge
Metabolite, NOx) tail gas increases year by year, in view of how NOx efficiently reduces NOx's to the mankind and the high risks of environment
Discharge causes the concern in the whole world.International Maritime Organization (International Maritime Organization, IMO) leads to
Cross《MARPOL73/78 pacts》Supplemental provisions VI, and come into effect New Year's Day in 2016 three more strict grade discharge standards
tierⅢ.No. 3192 suggestion that it is also proposed on controlling coastal vessel air pollution is advised by the National People's Congress in 2016.Therefore, reduce
NOx discharge turns into those skilled in the art's technical problem urgently to be resolved hurrily.
Selective-catalytic-reduction denitrified (Selective Catalytic Reduction Denox, SCR-DeNOx) technology
Be most widely used with the excellent performance such as its high efficiency, reliability and ease for maintenance as the whole world, most it is fruitful reduce
One of NOx method.SCR-DeNOx control systems include reactor subsections system, spray ammonia control subsystem, detection control subsystem
Etc. multiple parts.It in temperature is 250 DEG C~450 DEG C and to urge that the reaction mechanism of selective catalytic reduction, which is,
In the presence of agent vanadic anhydride/titanium dioxide (V2O5/TiO2), the NOx in ship tail gas is reduced by spraying ammoniacal liquor
For free of contamination nitrogen (N2) and water, wherein ammoniacal liquor is 37.5% aqueous solution of urea.
SCR-DeNOx main chemical reactions are as follows：
(1) hydrolysis of urea reacts：
CO(NH2)2+H2O→2NH3+CO2
(2) absorption of ammonia and desorption reaction：
(3) the SCR reactions of ammonia：
A fast reaction quantitative levels faster than standard reaction, the slow reaction ten in catalyst vanadium base (Vanadium)
Divide slow, and slow reaction is faster than standard reaction in iron-zeolite (Fe-Zeolite).But the NO in SCR-DeNOx systems
The 90% of NOx is accounted for, fast reaction is weaker, therefore the present invention is based on standard reaction.
In SCR-DeNOx control systems, the control of ammonia spraying amount subsystem is the most key part, is directly affected whole
The denitration rate and ammonia escape amount of system.Ammonia spraying amount control strategy mainly has two ways：Fixed ammonia nitrogen mol ratio is controlled and solid
Determine exit NOx concentration control.Both are essentially identical on control major loop, but fixed ammonia nitrogen mol ratio control is a kind of simple
Single loop control system, ammonia spraying amount is directly obtained according to ammonia nitrogen mol ratio.Which have ignored the change of exit NOx concentration value,
It can cause denitrogenation excessively when especially ammonia spraying amount is too high, the escape amount of ammonia greatly increases and forms secondary pollution.And fix
Mouth NOx concentration controlling party rule is a closed-loop control system, and denitration rate is function, and its ammonia nitrogen mol ratio is variable, is passed through
Regulation ammonia spraying amount can avoid denitrogenation excessive in time.
In the prior art, SCR-DeNOx sprays ammonia control subsystem using traditional ratio, integration, differential
(proportional-integral-derivative, PID) controller is controlled to ammonia spraying amount, still, due to SCR-
DeNOx ammonia spraying amount control subsystems have non-linear and time lag, and traditional PID controller has dynamic response relatively slow, robust
Property weak shortcoming, ammonia spraying amount is too low then it cannot be guaranteed that NOx conversion ratio, ammonia spraying amount is too high and can cause denitrogenation excessively, largely escapes
The ammonia of ease can also form secondary pollution.Therefore, it is difficult to obtain preferable denitration effect using traditional PID controller, easily
Cause denitration efficiency low or the problem of big amount of ammonia slip.
Therefore, how to provide it is a kind of can according to the control method of entrance oxynitride concentration accurate adjustment ammonia spraying amount and
System, the technical problem as those skilled in the art's urgent need to resolve.
The content of the invention
, can be according to entering it is an object of the invention to provide a kind of control method for selective catalytic reduction denitration device
Mouth oxynitride concentration accurate adjustment ammonia spraying amount, the escape amount of ammonia can also be reduced while denitration efficiency is improved.
To achieve the above object, the invention provides following scheme：
A kind of control method for selective catalytic reduction denitration device, the control method includes：
Set up the Simulation Experimental Platform of selective-catalytic-reduction denitrified system；
It is described imitative according to each given first entrance oxynitride concentration and the operation of first outlet oxynitride concentration
True experiment platform, obtains corresponding first ammonia spraying amount；
Using the multigroup off-line data of hard measurement analytical, spray ammonia control system model is obtained, wherein, described in each group
Off-line data includes：The first entrance oxynitride concentration, the first outlet oxynitride concentration and described right
The first ammonia spraying amount answered；
Bilinear transformation is carried out to the spray ammonia control system model using model predictive control method, obtained for controlling
The predictive control model of ammonia spraying amount.
Optionally, the use model predictive control method carries out bilinear transformation tool to the spray ammonia control system model
Body includes：
Bilinear transformation is carried out to the spray ammonia control system model, bilinear model is obtained；
The control parameter of the model predictive control method is determined according to the bilinear model；
The predictive control model is determined according to the control parameter and the bilinear model.
Optionally, the input quantity of the predictive control model includes second entrance oxynitride concentration and second outlet nitrogen
Oxygen compound concentration, the output quantity of the predictive control model includes the second ammonia spraying amount.
Optionally, the multigroup off-line data of the use hard measurement analytical is specifically included：
Multigroup off-line data is analyzed using the flexible measurement method of time series autoregression slip.
Optionally, the spray ammonia control system model is:
A(q-1) y (t)=B (q-1)u(t-1)+C(q-1) e (t),
Wherein, y (t) represents second ammonia spraying amount, and u (t) represents input quantity, u (t)=(u1(t) u2(t))T, u1(t)
Represent the second outlet oxynitride concentration, u2(t) the second entrance oxynitride concentration is represented, t represents the time
Variable, e (t) represents noise signal, A (q-1) represent the corresponding multinomial of second ammonia spraying amount, B (q-1) represent the input
Measure corresponding multinomial, C (q-1) represent the corresponding multinomial of the noise signal.
The present invention also aims to provide a kind of control system for selective catalytic reduction denitration device, Neng Gougen
According to entrance oxynitride concentration accurate adjustment ammonia spraying amount, the escape amount of ammonia can also be reduced while denitration efficiency is improved.
To achieve the above object, the invention provides following scheme：
A kind of control system for selective catalytic reduction denitration device, the control system includes：
Emulation module, the Simulation Experimental Platform for setting up selective-catalytic-reduction denitrified system；
Data acquisition module, for according to each given first entrance oxynitride concentration and the conjunction of first outlet nitrogen oxidation
Thing concentration runs the Simulation Experimental Platform, obtains corresponding first ammonia spraying amount；
Ammonia control system module is sprayed, for using the multigroup off-line data of hard measurement analytical, spray ammonia control is obtained
System model, wherein, off-line data includes described in each group：The first entrance oxynitride concentration, the first outlet
Oxynitride concentration and corresponding first ammonia spraying amount；
PREDICTIVE CONTROL module, for carrying out bilinearity to the spray ammonia control system model using model predictive control method
Conversion, obtains the predictive control model for controlling ammonia spraying amount.
Optionally, the PREDICTIVE CONTROL module is specifically included：
Bilinear transformation unit, for carrying out bilinear transformation to the spray ammonia control system model, obtains bilinearity mould
Type；
Control parameter determining unit, the control for determining the model predictive control method according to the bilinear model
Parameter；
Forecast model determining unit, for determining the PREDICTIVE CONTROL according to the control parameter and the bilinear model
Model.
Optionally, the input quantity of the predictive control model includes second entrance oxynitride concentration and second outlet nitrogen
Oxygen compound concentration, the output quantity of the predictive control model includes the second ammonia spraying amount.
Optionally, the spray ammonia control system module is analyzed using the flexible measurement method of time series autoregression slip
Multigroup off-line data.
Optionally, the spray ammonia control system model is:
A(q-1) y (t)=B (q-1)u(t-1)+C(q-1) e (t),
Wherein, y (t) represents second ammonia spraying amount, and u (t) represents input quantity, u (t)=(u1(t) u2(t))T, u1(t)
Represent the second outlet oxynitride concentration, u2(t) the second entrance oxynitride concentration is represented, t represents the time
Variable, e (t) represents noise signal, A (q-1) represent the corresponding multinomial of second ammonia spraying amount, B (q-1) represent the input
Measure corresponding multinomial, C (q-1) represent the corresponding multinomial of the noise signal.
The specific embodiment provided according to the present invention, the invention discloses following technique effect：
The present invention carries out the model that identification obtains spray ammonia control system to multigroup off-line data using hard measurement analysis method,
Then bilinear transformation is carried out to spray ammonia control system model using model predictive control method and obtains predictive control model, obtained
Predictive control model can come real-time according to the outlet oxynitride concentration of setting and the entrance oxynitride concentration of prediction
Corresponding ammonia spraying amount is adjusted, the escape amount of ammonia can also be reduced while denitration efficiency is improved.
Brief description of the drawings
In order to illustrate more clearly about the embodiment of the present invention or technical scheme of the prior art, below will be to institute in embodiment
The accompanying drawing needed to use is briefly described, it should be apparent that, drawings in the following description are only some implementations of the present invention
Example, for those of ordinary skill in the art, on the premise of not paying creative work, can also be obtained according to these accompanying drawings
Obtain other accompanying drawings.
Fig. 1 is the flow chart of the embodiment of the present invention 1；
Fig. 2 is the flow chart of the step 14 of the embodiment of the present invention 1；
Fig. 3 is the structured flowchart of the embodiment of the present invention 2；
Fig. 4 is the structured flowchart of PREDICTIVE CONTROL module 24 in the embodiment of the present invention 2；
Fig. 5 is the flow chart of the embodiment of the present invention 3；
Fig. 6 is that the ammonia in the Simulation Experimental Platform of the embodiment of the present invention 3 is stored and conservation of energy module section；
Fig. 7 is the nitrogen oxide mass conservation module section in the Simulation Experimental Platform of the embodiment of the present invention 3；
Fig. 8 is the ammonia conservation of mass module section in the Simulation Experimental Platform of the embodiment of the present invention 3；
Fig. 9 is the entrance concentration of the oxynitrides of the embodiment of the present invention 3 and the change curve of exit concentration；
Figure 10 is the conversion ratio of the oxynitrides of the embodiment of the present invention 3；
Figure 11 is the flow chart of ARMAX Model Distinguishes in the embodiment of the present invention 3；
Figure 12 is ARMAX Model Distinguish fitted figures in the embodiment of the present invention 3；
Figure 13 is the structured flowchart of MPC predictive controllers in the embodiment of the present invention 3；
Figure 14 is the analogous diagram of MPC controller and PID controller in the embodiment of the present invention 3；
Figure 15 is the comparison figure that the embodiment of the present invention 3 exports oxynitride concentration；
Figure 16 is the comparison figure of the escape amount of the ammonia of the embodiment of the present invention 3.
Embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is carried out clear, complete
Site preparation is described, it is clear that described embodiment is only a part of embodiment of the invention, rather than whole embodiments.It is based on
Embodiment in the present invention, it is every other that those of ordinary skill in the art are obtained under the premise of creative work is not made
Embodiment, belongs to the scope of protection of the invention.
It is an object of the invention to provide a kind of control method and control system for selective catalytic reduction denitration device,
Escaping for ammonia can also be reduced while denitration efficiency is improved according to entrance oxynitride concentration accurate adjustment ammonia spraying amount
Ease amount.
In order to facilitate the understanding of the purposes, features and advantages of the present invention, it is below in conjunction with the accompanying drawings and specific real
Applying mode, the present invention is further detailed explanation.
Embodiment 1：
As shown in figure 1, the control method for selective catalytic reduction denitration device includes：
Step 11：Set up the Simulation Experimental Platform of selective-catalytic-reduction denitrified system；
Step 12：Run according to each given first entrance oxynitride concentration and first outlet oxynitride concentration
The Simulation Experimental Platform, obtains corresponding first ammonia spraying amount；
Step 13：Multigroup off-line data is analyzed using the flexible measurement method of time series autoregression slip, sprayed
Ammonia control system model, wherein, each group off-line data includes：First entrance oxynitride concentration, first outlet nitrogen oxidation
Compound concentration and corresponding first ammonia spraying amount.Wherein, spray ammonia control system model is:
A(q-1) y (t)=B (q-1)u(t-1)+C(q-1) e (t),
Wherein, y (t) represents the second ammonia spraying amount, and u (t) represents input quantity, u (t)=(u1(t) u2(t))T, u1(t) represent
Second outlet oxynitride concentration, u2(t) second entrance oxynitride concentration is represented, t represents time variable, and e (t) is represented
Noise signal, A (q-1) represent the corresponding multinomial of the second ammonia spraying amount, B (q-1) represent the corresponding multinomial of input quantity, C (q-1) table
Show the corresponding multinomial of noise signal.
Step 14：Bilinear transformation is carried out to spray ammonia control system model using model predictive control method, is used for
Control ammonia spraying amount predictive control model, wherein the input quantity of predictive control model include second entrance oxynitride concentration and
Second outlet oxynitride concentration, the output quantity of the predictive control model includes the second ammonia spraying amount.
As shown in Fig. 2 step 14 is specifically included：
Step 141：Bilinear transformation is carried out to spray ammonia control system model, bilinear model is obtained；
Step 142：The control parameter of model predictive control method is determined according to bilinear model；
Step 143：Predictive control model is determined according to control parameter and bilinear model.
The technical problem that the present invention exists for traditional ship diesel SCR denitrating system is improved design, it is proposed that
A kind of ammonia spraying amount control method of the boat diesel engine SCR denitration system based on ARMAX and MPC, can not only effectively improve denitration
Efficiency, moreover it is possible to effectively reduce the escape amount of ammonia, reduces secondary pollution.
Embodiment 2：
As shown in figure 3, a kind of control system for selective catalytic reduction denitration device includes：
Emulation module 21, the Simulation Experimental Platform for setting up selective-catalytic-reduction denitrified system；
Data acquisition module 22, for according to each given first entrance oxynitride concentration and first outlet nitrogen oxidation
Compound concentration runs Simulation Experimental Platform, obtains corresponding first ammonia spraying amount；
Ammonia control system module 23 is sprayed, it is multigroup for the flexible measurement method analysis using time series autoregression slip
Off-line data, obtains spray ammonia control system model, wherein, each group off-line data includes：First entrance oxynitride concentration,
First outlet oxynitride concentration and corresponding first ammonia spraying amount.
Specifically, spray ammonia control system model is:
A(q-1) y (t)=B (q-1)u(t-1)+C(q-1) e (t),
Wherein, y (t) represents the second ammonia spraying amount, and u (t) represents input quantity, u (t)=(u1(t) u2(t))T, u1(t) represent
Second outlet oxynitride concentration, u2(t) institute's second entrance oxynitride concentration is represented, t represents time variable, e (t) tables
Show noise signal, A (q-1) represent the corresponding multinomial of the second ammonia spraying amount, B (q-1) represent the corresponding multinomial of the input quantity, C
(q-1) represent the corresponding multinomial of the noise signal.
PREDICTIVE CONTROL module 24, for carrying out bilinearity change to spray ammonia control system model using model predictive control method
Change, obtain the predictive control model for controlling ammonia spraying amount, wherein, the input quantity of predictive control model includes second entrance nitrogen oxygen
Compound concentration and second outlet oxynitride concentration, the output quantity of predictive control model include the second ammonia spraying amount.
As shown in figure 4, PREDICTIVE CONTROL module 24 is specifically included：
Bilinear transformation unit 241, for carrying out bilinear transformation to spray ammonia control system model, obtains bilinearity mould
Type；
Control parameter determining unit 242, the control parameter for determining model predictive control method according to bilinear model；
Forecast model determining unit 243, for determining predictive control model according to control parameter and bilinear model.
Due to the good robustness that model predictive control method has, the non-linear of conventional PID controllers can be improved
And hysteresis quality.Therefore, the control system of the present embodiment can not only effectively improve the conversion ratio of NOx in denitrating system, but also
Ammonia escape amount can effectively be reduced, it is to avoid secondary pollution.
Embodiment 3：As shown in figure 5, the control method for selective catalytic reduction denitration device includes：
Step 31：Set up the Simulation Experimental Platform of selective-catalytic-reduction denitrified system：
According to the reaction mechanism of SCR-DeNOx systems, the SCR-DeNOx systems built in MATLAB simulation softwares it is imitative
True experiment platform is as Figure 6-Figure 8；
Step 32：Run according to each given first entrance oxynitride concentration and first outlet oxynitride concentration
Simulation Experimental Platform, obtains corresponding first ammonia spraying amount：
As shown in figure 9, initial NOx entrance concentration is distributed in 3000~4000ppm, initial outlet NOx concentration is distributed in
500~1500ppm, runs after Simulation Experimental Platform according to the ammonia spraying amount of setting, and the concentration for finally exporting NOx is stable in 500ppm
Near.Figure 10 is denitrating system NOx conversion ratio, and NOx conversion ratio is by reacting the 58.5925% of the incipient stage to denitration reaction
Into 89.9659% during stable state, operation result further demonstrates the SCR-DeNOx Simulation Experimental Platforms of the application foundation.
Step 33：Using the multigroup offline number of hard measurement analytical using time series autoregression slip
According to, spray ammonia control system model is obtained, wherein, each group off-line data includes：First entrance oxynitride concentration, first go out
Mouth oxynitride concentration and corresponding first ammonia spraying amount：
To each group off-line data, including first entrance NOx concentration, first outlet NOx concentration and the first ammonia spraying amount, carry out soft
It is ARMAX Model Distinguishes to measure analysis, obtains the model of spray ammonia control system.
Time series autoregressive moving-average model includes：Autoregression model AR, moving average model MA and autoregression
Moving average model (Auto-Regressive Moving Average Mode, ARMAX).As shown in figure 11, ARMAX models
The step of identification, includes：(1) each group off-line data is pre-processed；(2) ARMAX models are set up.The pretreatment of wherein data includes：Adopt
The trend term that trend (detrend) function eliminates each group off-line data is spent, the stationarity to data is tested；To each group from
Line number evidence is normalized, it is to avoid model data increases simulation time because of the singularity of sample, so that operation result
The problem of can not restraining；Take and ask correlation function and sub- auto-correlation function value, with determine model data meet ARMAX model will
Ask.
During model foundation, final prediction error criterion (the Final Prediction of data are calculated respectively
Error Criterion, FPE), information loss minimum criteria (Akaika Information Criterion, AIC) and square
The value of root error (Root Mean Square Error, RMSE), and ARMAX model order is determined, to determine ARMAX models
The matrix of identification.
The present invention is from the ARMAX time series models of the output of two input one, the citation form of ARMAX time series models
For：
A(q-1) y (t)=B (q-1)u(t-1)+C(q-1)e(t)
Wherein, u (t) is input variable, and y (t) is output variable, and e (t) is noise signal, multinomial A (q), B (q), C
(q) model order is respectively na, nb1, nb2 and nc.In the present embodiment, y (t) represents the second ammonia spraying amount, and u (t) represents input
Amount, u (t)=(u1(t) u2(t))T, u1(t) second outlet oxynitride concentration, u are represented2(t) institute's second entrance nitrogen oxygen is represented
Compound concentration, t represents time variable, and e (t) represents noise signal, A (q-1) represent the corresponding multinomial of the second ammonia spraying amount, B
(q-1) represent the corresponding multinomial of the input quantity, C (q-1) represent the corresponding multinomial of the noise signal.
The method for determining model order is a lot, such as minimizes final predicated error method (FPE), minimum information criterion method
(AIC), correlation coefficient process, error of fitting (error in equation) method etc..Error of fitting method is to be based on principle of least square method, according to mould
Whether type there is less residual sum of squares (RSS) to carry out the quality of judgment models, and the corresponding order of minimum FPE/AIC values is model
Order.The present invention is based on error of fitting (root-mean-square error RMSE), and root-mean-square error calculation formula is as follows：
Wherein, RMSE represents root-mean-square error, and N represents the number of discrete data, yi,modelThe input value of model is represented,
yi,outThe value actually obtained is represented, the exponent number of model is determined with reference to FPE and AIC criterion, it is to avoid the error of single criterion selection,
In the case of similar nature, the relatively low ARMAX models of prioritizing selection order.
FPE () function and AIC () function that the calculating of FPE values and AIC values is carried using MATLAB, from na=nb1=
Nb2=1 starts examination and gathered, the final order for determining model.
The off-line data obtained for step 32, hard measurement analysis is carried out using ARMAX time series models.The present embodiment
In ARMAX hard measurements analysis, using error of fitting RMSE, with reference to FPE criterions and AIC criterion, be more or less the same in error of fitting
In the case of, it is preferential to select then lower-order model.Table 1 is corresponding RMSE value, FPE values and AIC values under different orders, accordingly, it is determined that
The order of the ARMAX models is na=2, nb1=3, nb2=3 respectively, and loss function is 1.09947e-4, and Model Distinguish is obtained
Result be idpoly discrete time models (Discrete-timeIDPOLYmodel)：
A (q)=1-1.77q-1+0.7767q-2(2),
Wherein, q represents time-shifting operator.
Corresponding RMSE, FPE and AIC value of the different model orders of table 1
Figure 12 is ARMAX Model Distinguish fitted figures, wherein '+' point diagram is actual sampling curve figure, '-' solid line is
The model curve figure that ARMAX identifications are obtained, Model Distinguish curve is very identical with actual curve figure, the ARMAX Model Distinguishes
Accuracy is higher.
The present embodiment is distinguished by carrying out ARMAX time series hard measurements to the off-line data that operation simulation test platform is obtained
Know, obtain the model of spray ammonia control subsystem, the error that NOx gas analyzers are brought by cross sensitivity can be prevented effectively from,
And then bring error to the initial data for modeling.
Step 34：Bilinear transformation is carried out to the spray ammonia control system model using model predictive control method, obtained
Predictive control model for controlling ammonia spraying amount：
According to the result of Time Series AR MAX Model Distinguishes, use the method that bilinearity changes by continuous system with equivalent
Discrete system present, that is, be expressed as SCR denitration system spray ammonia control system model.Binding model PREDICTIVE CONTROL (Model
Predictive Control, MPC) method is controlled to spray ammonia control system, and the valve available functions for adjusting ammonia spraying amount turn
The transmission function G of ammonia spraying amount MV and exit NOx concentration for acquisition1(s) and inlet NOx concentration MD and exit NOx concentration biography
Delivery function G2(s), so as to set up two inputs, the predictive control model of the stationary exit NOx concentration of an output so that SCR-
DeNOx systems can not only improve denitration rate, and can reduce the escape amount of ammonia.
The method of bilinearity change：According to the relation z=e between z expression formulas and Laplace expression formulaTs, can deduce：
Wherein,Z represents z-plane domain, and s represents s domains, and T represents sampling time interval.
Have under the conditions of low order：
It is respectively X (s), Y (s) continuous system to input and outputDiscretization, then have：
Wherein, a, b and c represent coefficient value, and X (z), Y (z) represent the input and output of discrete system respectively.
Formula (5) can be reduced to：
Formula (6) is inversely transformed into：
As shown in Figure 13 and Figure 14, the predictive control model based on MPC model predictive control methods enters one for one two and gone out
System, wherein ammonia spraying amount is manipulating variable (Manipulated variables, MV), and entrance NOx concentration disturbs for feedforward
(Measured disturbances, MD), outlet NOx variable concentration is sets target, and ammonia spraying amount is performance variable u (k),
Exit NOx concentration set-point is w (k), and ym (k) is the prediction exit NOx concentration of model, and actual exit NOx concentration is y (k).
It is the predictive control model based on MPC control methods and the control mould based on traditional PID control as shown in figure 14
Type, wherein the design parameter of the predictive control model based on MPC control methods includes：
(1) the valve available functions of regulation ammonia spraying amount switch to the transmission function for obtaining ammonia spraying amount (MV) and exit NOx concentration
For G1(s)：
(2) transmission function of inlet NOx concentration (MD) and exit NOx concentration is G2(s)：
(3) according to transmission function G1And G (s)2(s), gathered by examination pre- with simulation study setting predictive control model i.e. MPC
Survey the parameter of controller：
Wherein, sample frequency will meet aromatic sampling thheorem, and sample frequency is greater than twice of cut-off frequency.If adopted
Sample cycle T is long, can increase error, reduces the dynamic property of system, otherwise the too small increase amounts of calculation of T, it is possible that it is non-most
Small phase zero point, influences the stability of closed-loop system, therefore, T selection should between control effect and stability comprehensive consideration.In advance
The time that survey time domain P selection approximately rises with during is equal.P size can influence the stability and rapidity of system.P is such as
Fruit very little, existing makes the problem of multi-step prediction is changed into Single-step Prediction, if P is very big, in optimization process, the output of subsequent time
Predicted value may be solely dependent upon the stable response of control M controlling increment of time domain.P is excessive simultaneously can also to control order of matrix
Secondary increase, increases the calculating time.The main dynamic part that general P will be responded when choosing comprising object (pulse or step), with this
Initial option P is adjusted, and the size of P values is adjusted according to simulation result.The future that control time domain M is represented to be calculated and determined
The number that controlled quentity controlled variable changes, so M≤P, M are smaller so that system response is very slow.The vibration of control action can be eliminated by reducing M,
Stability is improved, while the required time can also be reduced by reducing M, the real-time of system is improved.
In the present embodiment, prediction time domain P is set to 100, and control time domain M is set to 2 (P >=M), and sample frequency is set to 0.1.
(4) weights of predictive controller are set according to the importance of each variable：
Because the regulation of ammonia spraying amount can set the weights of ammonia spraying amount depending on the entrance and exit concentration of nitrogen oxides
That puts is a little bit smaller.Because selecting the control mode of stationary exit nitrous oxides concentration, therefore the concentration for exporting nitrogen oxides is weighed
Value is set to 1.Because robust coefficient can influence the stability and response speed of system, substantially compromise is chosen, while can be according to imitative
True result is suitably adjusted, and the default value for making overall gain is 1 so that the ability of tracking of system reaches minimum effect.
In the present embodiment, the weights of performance variable ammonia spraying amount are 0.1, and the weights of exit NOx concentration are set to 1, the Shandong of system
Rod coefficient is set to 0.6, and total gain is 1.
(5) setting of design and simulation device, i.e. SetPoints, SetPoints influence control reference signals.
(6) the discharge criterion according to Tier III, the concentration for finally setting outlet NOx is 80ppm, and entrance NOx disturbance becomes
Amount is that initial value is 0ppm, and final value is 7ppm step signal function.
Figure 15 is the exit NOx concentration for using the predictive control model of the application and being obtained using traditional PID controller
Comparison figure, wherein, the parameter of traditional PID control, including ratio P=9 integrates I=2, differential D=0.As seen from Figure 15, MPC
The spray ammonia system curve of predictive controller reaches the setting value 80ppm of NOx concentration in 10s, and conversion rate of NOx reaches 95.56%.And
PID controller concussion is larger, and time to peak is the NOx concentration value that setting is reached after 5s, 18s, and overshoot is 11.1%, NOx's
Conversion ratio is only 89.9%.
As seen from Figure 16, the escape amount of MPC controller and PID ammonia is respectively 1.6317ppm and 27.2521ppm, in advance
Observing and controlling simulation can greatly reduce the escape amount and escapement ratio of ammonia.Therefore, the predictive control model that the application is provided is not
Denitration rate is improve only, and reduces the escaping of ammonia, SCR-DeNOx systems are optimized.
The present embodiment selects stationary exit NOx control modes, according to going out for NOx concentration in tail gas, tail gas amount and setting
Mouth NOx concentration value, is designed to SCR-DeNOx sprays ammonia control subsystem.Due to SCR-DeNOx ammonia spraying amounts of the prior art
Control subsystem has non-linear and time lag, is difficult to obtain preferable denitrating system using traditional PID controller.The present invention
PID control is replaced with advanced forecast Control Algorithm, the ammonia spraying amount in SCR-DeNOx systems is adjusted, is ensureing denitration
In system while NOx conversion ratio, it is ensured that amount of ammonia slip in the reasonable scope, reduces ammonia escape amount.
The embodiment of each in this specification is described by the way of progressive, and what each embodiment was stressed is and other
Between the difference of embodiment, each embodiment identical similar portion mutually referring to.For system disclosed in embodiment
For, because it is corresponded to the method disclosed in Example, so description is fairly simple, related part is said referring to method part
It is bright.
Specific case used herein is set forth to the principle and embodiment of the present invention, and above example is said
The bright method and its core concept for being only intended to help to understand the present invention；Simultaneously for those of ordinary skill in the art, foundation
The thought of the present invention, will change in specific embodiments and applications.In summary, this specification content is not
It is interpreted as limitation of the present invention.
Claims (10)
1. a kind of control method for selective catalytic reduction denitration device, it is characterised in that the control method includes：
Set up the Simulation Experimental Platform of selective-catalytic-reduction denitrified system；
It is real according to each given first entrance oxynitride concentration and the first outlet oxynitride concentration operation emulation
Platform is tested, corresponding first ammonia spraying amount is obtained；
Using the multigroup off-line data of hard measurement analytical, spray ammonia control system model is obtained, wherein, it is offline described in each group
Data include：The first entrance oxynitride concentration, the first outlet oxynitride concentration and described corresponding
First ammonia spraying amount；
Bilinear transformation is carried out to the spray ammonia control system model using model predictive control method, obtained for controlling spray ammonia
The predictive control model of amount.
2. control method according to claim 1, it is characterised in that the use model predictive control method is to the spray
Ammonia control system model carries out bilinear transformation and specifically included：
Bilinear transformation is carried out to the spray ammonia control system model, bilinear model is obtained；
The control parameter of the model predictive control method is determined according to the bilinear model；
The predictive control model is determined according to the control parameter and the bilinear model.
3. control method according to claim 1, it is characterised in that the input quantity of the predictive control model includes second
Entrance oxynitride concentration and second outlet oxynitride concentration, the output quantity of the predictive control model include the second spray
Ammonia amount.
4. control method according to claim 3, it is characterised in that the multigroup institute of use hard measurement analytical
Off-line data is stated to specifically include：
Multigroup off-line data is analyzed using the flexible measurement method of time series autoregression slip.
5. control method according to claim 4, it is characterised in that the spray ammonia control system model is:
A(q-1) y (t)=B (q-1)u(t-1)+C(q-1) e (t),
Wherein, y (t) represents second ammonia spraying amount, and u (t) represents input quantity, u (t)=(u1(t) u2(t))T, u1(t) institute is represented
State second outlet oxynitride concentration, u2(t) the second entrance oxynitride concentration is represented, t represents time variable, e
(t) noise signal, A (q are represented-1) represent the corresponding multinomial of second ammonia spraying amount, B (q-1) represent the input quantity correspondence
Multinomial, C (q-1) represent the corresponding multinomial of the noise signal.
6. a kind of control system for selective catalytic reduction denitration device, it is characterised in that the control system includes：
Emulation module, the Simulation Experimental Platform for setting up selective-catalytic-reduction denitrified system；
Data acquisition module, for dense according to each given first entrance oxynitride concentration and first outlet oxynitrides
The degree operation Simulation Experimental Platform, obtains corresponding first ammonia spraying amount；
Ammonia control system module is sprayed, for using the multigroup off-line data of hard measurement analytical, spray ammonia control system is obtained
Model, wherein, off-line data includes described in each group：The first entrance oxynitride concentration, the first outlet nitrogen oxygen
Compound concentration and corresponding first ammonia spraying amount；
PREDICTIVE CONTROL module, for carrying out bilinearity change to the spray ammonia control system model using model predictive control method
Change, obtain the predictive control model for controlling ammonia spraying amount.
7. control system according to claim 6, it is characterised in that the PREDICTIVE CONTROL module is specifically included：
Bilinear transformation unit, for carrying out bilinear transformation to the spray ammonia control system model, obtains bilinear model；
Control parameter determining unit, for determining that the control of the model predictive control method is joined according to the bilinear model
Number；
Forecast model determining unit, for determining the PREDICTIVE CONTROL mould according to the control parameter and the bilinear model
Type.
8. control system according to claim 6, it is characterised in that the input quantity of the predictive control model includes second
Entrance oxynitride concentration and second outlet oxynitride concentration, the output quantity of the predictive control model include the second spray
Ammonia amount.
9. control system according to claim 8, it is characterised in that the spray ammonia control system module uses time series
The flexible measurement method of autoregression slip analyzes multigroup off-line data.
10. control system according to claim 9, it is characterised in that the spray ammonia control system model is:
A(q-1) y (t)=B (q-1)u(t-1)+C(q-1) e (t),
Wherein, y (t) represents second ammonia spraying amount, and u (t) represents input quantity, u (t)=(u1(t) u2(t))T, u1(t) institute is represented
State second outlet oxynitride concentration, u2(t) the second entrance oxynitride concentration is represented, t represents time variable, e
(t) noise signal, A (q are represented-1) represent the corresponding multinomial of second ammonia spraying amount, B (q-1) represent the input quantity correspondence
Multinomial, C (q-1) represent the corresponding multinomial of the noise signal.
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| CN109933884A (en) * | 2019-03-08 | 2019-06-25 | 华北电力大学（保定） | A method of towards coal unit SCR denitration system Neural network inverse control |
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| CN112627953A (en) * | 2020-12-22 | 2021-04-09 | 上海海事大学 | Ship SCR system ammonia injection amount control method based on ARMAX and MMPC |
| CN114183760A (en) * | 2021-12-01 | 2022-03-15 | 广州环投从化环保能源有限公司 | Garbage incinerator denitration control method based on multi-model weighted prediction |
| CN114183760B (en) * | 2021-12-01 | 2024-03-12 | 广州环投从化环保能源有限公司 | Garbage incinerator denitration control method based on multi-model weighted prediction |
| CN115598974A (en) * | 2022-09-02 | 2023-01-13 | 南京天洑软件有限公司（Cn） | Denitration system model prediction control method and device based on linear system identification |
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