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CN108958031B - Post combustion CO2Coordinated prediction control method for trapping coal-fired power generation system - Google Patents

Post combustion CO2Coordinated prediction control method for trapping coal-fired power generation system Download PDF

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CN108958031B
CN108958031B CN201810794279.3A CN201810794279A CN108958031B CN 108958031 B CN108958031 B CN 108958031B CN 201810794279 A CN201810794279 A CN 201810794279A CN 108958031 B CN108958031 B CN 108958031B
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CN108958031A (en
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吴啸
沈炯
李益国
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Southeast University
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Abstract

The invention discloses a post-combustion CO2The coordinated prediction control method for the capture coal-fired power generation system can realize the mutual coordination and deep combination of the coal-fired power station engine furnace system and the carbon capture system, improve the flexible operation quality of the coal-fired power station engine furnace system and fully exert the efficiency of the coal-fired power station engine furnace system in the aspects of power generation and carbon emission reduction.

Description

Post combustion CO2Coordinated prediction control method for trapping coal-fired power generation system
Technical Field
The invention relates to the technical field of thermal process control, in particular to post-combustion CO2A coordinated prediction control method for a capture coal-fired power generation system.
Background
With the increasing severity of greenhouse effect and related climate ecological problems, CO emission reduction2Has become a key measure for the international society to cope with climate change. As the main equipment for power supply, the coal-fired power generating set is CO2Most stable, concentrated source of emissions, its CO2Capture is recognized by numerous authorities as the realization of large-scale CO within the next 30 years2The most direct and effective technical means for emission reduction.
In the existing coal-fired power generation system CO2Post-combustion CO capture technology based on chemical absorption2Direct CO separation from flue gas by capture technology2Has excellent inheritance and better technical applicability to the prior generator set, is the most mature power station carbon capture technology at present, and has a plurality of CO integrated after combustion in China and the world2The trapped pilot coal-fired power plant is put into operation.
At present, a great deal of research results are available on the traditional and advanced control means of coal-fired power generation systems; with respect to post-combustion CO2Feedback control design studies for trapping systems have been partially successful, but not complete. For integrated post-combustion CO2For a trapping coal-fired power generation system, the characteristics of the trapping coal-fired power generation system are greatly different from those of an independent system, and the control research of the trapping coal-fired power generation system is not common. How to design an effective operation control means, fully utilize the interaction between two systems and furthest exert the purposes of the systems in the aspects of power generation and carbon emission reductionThe problem to be solved. Thus, a post-combustion CO was developed2There is a need for a method of controlling the operation of a capture coal-fired power generation system.
Disclosure of Invention
The invention aims to solve the technical problem of providing CO after combustion2The coordinated prediction control method for the capture coal-fired power generation system can realize CO2The whole coal-fired power generation system is collected and coordinately controlled, and the efficiency of the coal-fired power generation system in the aspects of power generation and carbon emission reduction is fully exerted.
To solve the above technical problems, the present invention provides a post-combustion CO2The coordinated prediction control method for the trapping coal-fired power generation system comprises the following steps:
(1) a3 multiplied by 3 multivariable predictive control system which takes a coal feeding amount instruction, a steam turbine valve opening degree and a water feeding valve opening degree as operation variables and takes power generation power, main steam pressure and an intermediate point enthalpy value as controlled variables is constructed for a coal-fired power generation unit engine furnace system, and CO is considered in the design process2The trapping system takes the extracted steam flow at the connection position of the middle and low pressure cylinders of the steam turbine as a disturbance signal;
(2) for post-combustion CO based on chemisorption2The structure of the trapping system takes lean solution flow and steam extraction flow of a steam turbine as operation variables, and CO2A 2 x 2 multivariable predictive control system with the trapping rate and the reboiler temperature as controlled variables takes the flue gas flow of a coal-fired power station as a disturbance signal in the design process;
(3) identifying a coal feeding instruction-flue gas amount model, predicting the flue gas amount generated in the operation of the power station in a future period of time according to a future coal feeding amount sequence calculated by a power station machine furnace system prediction controller during online operation, and sending the flue gas amount measured at the current moment and the predicted future flue gas amount into CO2The capture system predictive controller acts as a feed forward signal; correspondingly, the current steam extraction flow and CO of the steam turbine are calculated at each sampling moment2The future steam extraction amount estimated by the collection system prediction controller is sent to the power station machine furnace system prediction controller as a feedforward signal, and the optimal control sequences of the two sets of prediction control systems are respectively calculated;
(4) aiming at the designed coordinated predictive control method, the CO after combustion is provided2Three modes of operation of the coal-fired power generation system are captured.
Preferably, in the step (1), the design of the predictive controller of the coal-fired power generation unit furnace system comprises the following specific steps:
(11) in order to give coal amount command uaSteam turbine valve opening ubOpening u of water supply valvecIs input into the system
Figure BDA0001735619790000021
Figure BDA0001735619790000022
The extraction flow of the steam turbine is system disturbance f and electric power yaMain steam pressure ybAnd intermediate point enthalpy ycIs output to the system
Figure BDA0001735619790000023
Carrying out an excitation test to obtain dynamic data of system operation;
(12) selecting a sampling period TsIdentifying a furnace system prediction model based on the obtained data;
(13) through model recursion, output sequence of the system in a future period of time is obtained
Figure BDA0001735619790000024
Expressed as a sequence of future input increments
Figure BDA0001735619790000025
And perturbation increment sequence
Figure BDA0001735619790000026
A function of (a); in the formula, NyTo predict the time domain, NuTo control the time domain.
Figure BDA0001735619790000027
Respectively representing time k to k + Ny-an estimate of the system output at time 1;
Figure BDA0001735619790000028
respectively represent the k moment to k +Nu-1 input increments of the system at time;
Figure BDA0001735619790000029
respectively representing time k to k + Nu-1 a disturbance increment of the system at time instant; suppose that the control and perturbation acts on NuRemain unchanged after the moment, i.e.
Figure BDA00017356197900000210
Figure BDA00017356197900000211
(14) Taking into account performance indicators
Figure BDA00017356197900000212
Wherein, QfAnd RfIs a weight matrix for adjusting the quality of input/output control,
Figure BDA00017356197900000213
rfis the future NyThe sequence of set points that the system wants to reach at the moment,
Figure BDA0001735619790000031
Figure BDA0001735619790000032
respectively representing time k to k + Ny-1 time system set point;
at each sampling instant, the following input amplitude and rate constraints are considered:
Figure BDA0001735619790000033
Figure BDA0001735619790000034
for the performance indexOptimizing to obtain optimal control sequence and using its first element ukActing on the engine furnace object of the coal-fired power plant.
Preferably, in step (2), the post-combustion CO is chemisorbed2The design of the prediction controller of the trapping system comprises the following specific steps:
(21) at lean solution flow rate udSteam extraction flow u of steam turbineeIs input into the system
Figure BDA0001735619790000035
The flue gas flow is system disturbance g, CO2Trapping rate ydReboiler temperature yeIs output to the system
Figure BDA0001735619790000036
Carrying out an excitation test to obtain dynamic data of system operation;
(22) selecting a sampling period TsIdentifying a capture system prediction model based on the obtained data;
(23) through model recursion, output sequence of the system in a future period of time is obtained
Figure BDA0001735619790000037
Expressed as a sequence of future input increments
Figure BDA0001735619790000038
And perturbation increment sequence
Figure BDA0001735619790000039
A function of (a); in the formula, NyTo predict the time domain, NuIs a control time domain;
Figure BDA00017356197900000310
respectively representing time k to k + Ny-an estimate of the system output at time 1;
Figure BDA00017356197900000311
respectively representing time k to k + Nu-1 input increments of the system at time;
Figure BDA00017356197900000312
respectively representing time k to k + Nu-1 a disturbance increment of the system at time instant; suppose that the control and perturbation acts on NuRemain unchanged after the moment, i.e.
Figure BDA00017356197900000313
Figure BDA00017356197900000314
(24) Taking into account performance indicators
Figure BDA0001735619790000041
Wherein, QfAnd RfIs a weight matrix for adjusting the quality of input/output control,
Figure BDA0001735619790000042
rfis the future NyThe sequence of set points that the system wants to reach at the moment,
Figure BDA0001735619790000043
Figure BDA0001735619790000044
respectively representing time k to k + Ny-1 time system set point;
at each sampling instant, the following input amplitude and rate constraints are considered:
Figure BDA0001735619790000045
Figure BDA0001735619790000046
optimizing the performance index to obtain the optimal control sequence and using the first element ukActing on CO2The system object is captured.
Preferably, in the step (4), the three modes are specifically: the conventional mode is as follows: the system receives the power generation power and the capture rate instruction given by the dispatching layer and is responsible for realizing the rapid and stable tracking of the new set value; fast peak regulation mode: the power station boiler system prediction controller receives a power generation power instruction given by a scheduling layer and carries out tracking; the capture system increases and decreases the steam extraction flow of the steam turbine at the maximum speed until the steam extraction reaches the amplitude or the power station completes 95% of variable load adjustment, so as to accelerate the load change speed of the power station and maintain the temperature stability of reboiling steam by adjusting the flow of the barren solution; strict carbon capture mode: the change rate of the coal feeding amount is limited to be matched with the change rate of the barren liquor of the capture system, so that the influence of the change of the smoke amount on the capture system in the load lifting process of the power station can be basically compensated by the barren liquor flow, and the capture rate does not fluctuate greatly.
The invention has the beneficial effects that: post combustion CO as claimed in the invention2The coordinated prediction control method for the trapping coal-fired power generation system effectively solves the control problems of large inertia, strong coupling and strict constraint of the system by using a prediction control technology; the current measurable extraction steam flow and flue gas flow and the predicted values of the extraction steam flow and the flue gas flow in a future period of time are used as feed-forward signals to be sent to a prediction control system, so that the mutual coordination between a power generation system and a carbon capture system is enhanced, and the deep combination between the two systems is realized; based on the coordinated predictive control system, three operation modes of conventional operation, rapid peak regulation and strict carbon capture are provided, and CO after integral combustion is fully exerted2The efficiency of the coal-fired power generation system in the aspects of power generation and carbon emission reduction is captured, and simulation results prove that the method is used for CO after combustion2Capturing the effectiveness and superiority of coal-fired power generation system control.
Drawings
FIG. 1 is a post combustion CO of the present invention2The structure of the trapping coal-fired power generation system is schematic.
FIG. 2 is a schematic flow chart of the method of the present invention.
FIG. 3(a) shows the control of post-combustion CO according to the present invention2(graph showing effects of trapping coal-fired power generation system in varying power generation and trapping rate: (Generated power).
FIG. 3(b) shows the control of post-combustion CO according to the present invention2The effect graphs (collection rate, reboiler temperature) when the collection power and collection rate of the coal-fired power generation system are changed.
FIG. 4(a) shows the control of post-combustion CO according to the present invention2And (4) collecting an effect diagram (coal supply amount instruction and steam turbine valve opening degree) when the coal-fired power generation system changes the power generation power and the collection rate.
FIG. 4(b) shows the control of post-combustion CO according to the present invention2And (4) capturing effect graphs (barren solution flow and extraction steam flow) when the coal-fired power generation system changes the power generation power and the capturing rate.
FIG. 5(a) shows the control of post-combustion CO according to the present invention2The effect map (generated power) when the generated power is rapidly changed by the coal-fired power generation system is captured.
FIG. 5(b) shows the control of post-combustion CO according to the present invention2The trapping coal-fired power generation system rapidly changes the power generation efficiency (trapping rate, reboiler temperature).
FIG. 6(a) shows CO control after combustion according to the present invention2And (4) capturing an effect diagram (coal feeding amount instruction and steam turbine valve opening degree) when the coal-fired power generation system rapidly changes the power generation power.
FIG. 6(b) shows the control of post-combustion CO according to the present invention2And capturing an effect diagram (barren solution flow and extraction steam flow) when the coal-fired power generation system rapidly changes the power generation power.
Detailed Description
As shown in FIG. 2, a post-combustion CO2The coordinated prediction control method for the trapping coal-fired power generation system comprises the following steps:
(1) a3 multiplied by 3 multivariable predictive control system which takes a coal feeding amount instruction, a steam turbine valve opening and a water feeding valve opening as operation variables and takes power generation power, main steam pressure and an intermediate point enthalpy value as controlled variables is constructed for a coal-fired power generation unit engine-furnace system. CO is taken into account during the design process2The trapping system takes the extracted steam flow at the connection position of the middle and low pressure cylinders of the steam turbine as a disturbance signal;
(2) for post-combustion CO based on chemisorption2The structure of the trapping system takes lean solution flow and steam extraction flow of a steam turbine as operation variables, and CO2A collection rate and2 x 2 multivariable predictive control system with reboiler temperature as the controlled variable. In the design process, the flue gas flow of the coal-fired power station is taken as a disturbance signal;
(3) identifying a coal feeding instruction-flue gas amount model, predicting the flue gas amount generated in the operation of the power station in a future period of time according to a future coal feeding amount sequence calculated by a power station machine furnace system prediction controller during online operation, and sending the flue gas amount measured at the current moment and the predicted future flue gas amount into CO2The capture system predictive controller acts as a feed forward signal; correspondingly, the current steam extraction flow and CO of the steam turbine are calculated at each sampling moment2And the future steam extraction amount estimated by the collection system prediction controller is sent to the power station machine furnace system prediction controller to be used as a feedforward signal. Respectively calculating the optimal control sequences of the two sets of prediction control systems;
(4) aiming at the designed coordinated predictive control method, the CO after combustion is provided2Three modes of operation of the coal-fired power generation system are captured. The conventional mode is as follows: the system receives the power generation power and the capture rate instruction given by the dispatching layer and is responsible for realizing the rapid and stable tracking of the new set value;
(5) fast peak regulation mode: the power station boiler system prediction controller receives a power generation power instruction given by a scheduling layer and carries out tracking; the capture system increases and decreases the steam extraction flow of the steam turbine at the maximum speed until the steam extraction reaches the amplitude or the power station completes 95% of variable load adjustment, so as to accelerate the load change speed of the power station and maintain the temperature stability of reboiling steam by adjusting the flow of the barren solution;
(6) strict carbon capture mode: the change rate of the coal feeding amount is limited to be matched with the change rate of the barren liquor of the capture system, so that the influence of the change of the smoke amount on the capture system in the load lifting process of the power station can be basically compensated by the barren liquor flow, and the capture rate does not fluctuate greatly.
In the step (1), the design of the prediction controller of the coal-fired power generation unit furnace system comprises the following specific steps:
(11) in order to give coal amount command uaSteam turbine valve opening ubOpening u of water supply valvecInputting u ═ into the system
Figure BDA0001735619790000061
The extraction flow of the steam turbine is system disturbance f and electric power yaMain steam pressure ybAnd intermediate point enthalpy ycIs output to the system
Figure BDA0001735619790000062
Carrying out an excitation test to obtain dynamic data of system operation;
(12) selecting a sampling period TsIdentifying a machine furnace system prediction model for 10 s;
(13) through model recursion, output sequence of the system in a future period of time is obtained
Figure BDA0001735619790000063
Expressed as a sequence of future input increments
Figure BDA0001735619790000064
And perturbation increment sequence
Figure BDA0001735619790000065
A function of (a); in the formula, the time domain N is predictedyControl time domain N20u=10。
Figure BDA0001735619790000066
Figure BDA0001735619790000067
Respectively representing time k to k + Ny-an estimate of the system output at time 1;
Figure BDA0001735619790000068
respectively representing time k to k + Nu-1 input increments of the system at time;
Figure BDA0001735619790000069
respectively representing time k to k + Nu-1 disturbance increment of the system at time. We assume that the control and perturbation effect is on NuRemain unchanged after the moment, i.e.
Figure BDA00017356197900000610
Figure BDA00017356197900000611
(14) Taking into account performance indicators
Figure BDA0001735619790000071
Wherein, QfAnd RfIs a weight matrix for adjusting the quality of input/output control,
Figure BDA0001735619790000072
rfis the future NyThe sequence of set points that the system wants to reach at the moment,
Figure BDA0001735619790000073
Figure BDA0001735619790000074
respectively representing time k to k + Ny-1 time system set point;
at each sampling instant, the following input amplitude and rate constraints are considered:
Figure BDA0001735619790000075
Figure BDA0001735619790000076
optimizing the performance index to obtain the optimal control sequence and using the first element ukActing on the engine furnace object of the coal-fired power plant.
In step (2), the post-chemisorption CO is combusted2The design of the prediction controller of the trapping system comprises the following specific steps:
(21) at lean solution flow rate udSteam extraction flow u of steam turbineeIs input into the system
Figure BDA0001735619790000077
The flue gas flow is system disturbance g, CO2Trapping rate ydReboiler temperature yeIs output to the system
Figure BDA0001735619790000078
Carrying out an excitation test to obtain dynamic data of system operation;
(22) selecting a sampling period TsIdentifying a prediction model of the trapping system;
(23) through model recursion, output sequence of the system in a future period of time is obtained
Figure BDA0001735619790000079
Expressed as a sequence of future input increments
Figure BDA00017356197900000710
And perturbation increment sequence
Figure BDA00017356197900000711
A function of (a); in the formula, the time domain N is predictedyControl time domain N20u=10。
Figure BDA00017356197900000712
Figure BDA00017356197900000713
Respectively representing time k to k + Ny-an estimate of the system output at time 1;
Figure BDA00017356197900000714
respectively representing time k to k + Nu-1 input increments of the system at time;
Figure BDA00017356197900000715
respectively representing time k to k + Nu-1 disturbance increment of the system at time. We assume that the control and perturbation effect is on NuRemain unchanged after the moment, i.e.
Figure BDA0001735619790000081
Figure BDA0001735619790000082
(24) Taking into account performance indicators
Figure BDA0001735619790000083
Wherein, QfAnd RfIs a weight matrix for adjusting the quality of input/output control,
Figure BDA0001735619790000084
rfis the future NyThe sequence of set points that the system wants to reach at the moment,
Figure BDA0001735619790000085
Figure BDA0001735619790000086
respectively representing time k to k + Ny-1 time system set point;
at each sampling instant, the following input amplitude and rate constraints are considered:
Figure BDA0001735619790000087
Figure BDA0001735619790000088
optimizing the performance index to obtain the optimal control sequence and using the first element ukActing on CO2The system object is captured.
As shown in FIG. 1, the present invention integrates post-chemisorption combustion CO2The coal-fired supercritical unit of the trapping technology is taken as an object, prediction controllers are respectively established for two sets of systems, and the steam extraction flow and the smoke gas volume of a steam turbine at the current moment and the estimated values of the steam extraction flow and the smoke gas volume in a period of time in the future are usedSending the signal into a predictive control system as a feedforward signal, deeply combining a power generation system with a carbon capture system to obtain combusted CO2The coordinated prediction control method for the capture coal-fired power generation system can enhance CO after combustion on the whole2And collecting the operation and adjustment quality of the coal-fired power generation system. Three operation modes of conventional operation, accelerated peak regulation and strict carbon capture are provided aiming at the invented control strategy so as to give full play to the CO after integral combustion2The efficiency of the coal-fired power generation system in the aspects of power supply and carbon emission reduction is captured.
This example is to verify the post-combustion CO of the present invention2The effect of the operation control method of the trapping coal-fired power generation system is that the coordination control method of the invention is applied to CO after combustion with chemical adsorption2In a simulation model of a certain small coal-fired power generation system of the trapping technology, two sets of simulation tests are carried out: simulation experiment 1, coal-fired power plant is initially at 0.2MWe load, CO2The initial collection rate of the collection system was stabilized at 80%, and the plant power generation instruction set value was changed to 0.225MWe and 0.13MWe and the collection rate set value was changed to 60% and 90% in response to the scheduling instruction at t 300s and 3300 s.
As shown in fig. 3(a), 3(b), 4(a) and 4(b), in the figure, the solid line: the coordination and prediction control of the power generation-carbon capture integral system; dotted line: the power generation-carbon capture integral system is independently predicted and controlled; dotted line: PI feedback control of the power generation-carbon capture integral system; dot-dash line: and (5) setting the value. Post combustion CO by using predictive control methods2Compared with the traditional PI control, the flexible operation capability of the trapping coal-fired power generation system is greatly improved, and the variable working condition speed is obviously accelerated. The steam extraction flow and the flue gas volume of the steam turbine at the current moment and the estimated values of the steam extraction flow and the flue gas volume of the steam turbine at a future period are used as feed-forward signals to be sent to a prediction control system, so that the interaction between the power generation system and the carbon capture system is fully considered and utilized and is not unknown interference influencing the operation of each other. The coordination predictive control method has excellent control performance.
Simulation experiment 2, coal-fired power plant was initially at 0.17MWe load, CO2The initial collection rate of the collection system is stabilized at 70%, and the collection system is subjected to a scheduling command when t is 300s, and a power generation command of a power station is setThe constant value changes to 0.21MWe and load tracking is currently the most urgent regulatory task.
As shown in fig. 5(a), 5(b), 6(a) and 6(b), in the figure, the solid line: coordinated predictive control (acceleration peak regulation mode) of the power generation-carbon capture overall system; power generation-carbon capture overall system coordinated predictive control (conventional mode); dot-dash line: and (5) setting the value. CO for fast load-up of the power station after switching to the accelerated peak shaving mode2The capture system reduces the steam extraction at the highest speed, so that the steam can continue to work in the low-pressure cylinder to generate power, and the power generation power is quickly improved. It can be seen that the load ramp up process of the fast peak shaver mode is shortened by about 50 seconds compared to the conventional mode. Meanwhile, the temperature of the reboiler of the trapping system is stably controlled, and the requirement of safe operation is met.
Post combustion CO as claimed in the invention2The coordinated prediction control method for the trapping coal-fired power generation system effectively solves the control problems of large inertia, strong coupling and strict constraint of the system by using a prediction control technology. The current measurable extraction steam flow and flue gas flow and the estimated values of the extraction steam flow and the flue gas flow in a future period of time are used as feed-forward signals to be sent to a prediction control system, so that the mutual coordination between a power generation system and a carbon capture system is enhanced, and the deep combination between the two systems is realized. Based on the coordinated predictive control system, three operation modes of conventional operation, rapid peak regulation and strict carbon capture are provided, and CO after integral combustion is fully exerted2The efficiency of the coal-fired power generation system in the aspects of power generation and carbon emission reduction is captured.

Claims (3)

1. Post combustion CO2The coordination prediction control method for the trapping coal-fired power generation system is characterized by comprising the following steps of:
(1) a3 multiplied by 3 multivariable predictive control system which takes a coal feeding amount instruction, a steam turbine valve opening degree and a water feeding valve opening degree as operation variables and takes power generation power, main steam pressure and an intermediate point enthalpy value as controlled variables is constructed for a coal-fired power generation unit engine furnace system, and CO is considered in the design process2The trapping system takes the extracted steam flow at the connection position of the middle and low pressure cylinders of the steam turbine as a disturbance signal;
(2)for post-combustion CO based on chemisorption2The structure of the trapping system takes lean solution flow and steam extraction flow of a steam turbine as operation variables, and CO2A 2 x 2 multivariable predictive control system with the trapping rate and the reboiler temperature as controlled variables takes the flue gas flow of a coal-fired power station as a disturbance signal in the design process;
(3) identifying a coal feeding instruction-flue gas volume model, predicting the flue gas volume to be generated in the operation of the power station in a future period of time according to a future coal feeding volume sequence calculated by a coal-fired power generation unit boiler system prediction controller during online operation, and sending the flue gas volume measured at the current moment and the predicted future flue gas volume into CO2The capture system predictive controller acts as a feed forward signal; correspondingly, the current steam extraction flow and CO of the steam turbine are calculated at each sampling moment2The future steam extraction amount estimated by the capture system predictive controller is sent to the coal-fired power generation unit boiler system predictive controller to be used as a feedforward signal, and the optimal control sequences of the two sets of predictive control systems are respectively calculated;
(4) aiming at the designed coordinated predictive control method, the CO after combustion is provided2Three operation modes of the coal-fired power generation system are collected; the three operation modes are specifically: the conventional mode is as follows: the system receives the power generation power and the capture rate instruction given by the dispatching layer and is responsible for realizing the rapid and stable tracking of the new set value; fast peak regulation mode: receiving a power generation power instruction given by a scheduling layer by a coal-fired power generation unit boiler system prediction controller, and tracking; the capture system increases and decreases the steam extraction flow of the steam turbine at the maximum speed until the steam extraction reaches the amplitude or the power station completes 95% of variable load adjustment, so as to accelerate the load change speed of the power station and maintain the temperature stability of reboiling steam by adjusting the flow of the barren solution; strict carbon capture mode: the change rate of the coal feeding amount is limited to be matched with the change rate of the barren liquor of the capture system, so that the influence of the change of the smoke amount on the capture system in the load lifting process of the power station can be basically compensated by the barren liquor flow, and the capture rate does not fluctuate greatly.
2. Post combustion CO according to claim 12The coordinated prediction control method for the trapping coal-fired power generation system is characterized in that in the step (1), a coal-fired power generation unitThe design of a predictive controller of a furnace system comprises the following specific steps:
(11) in order to give coal amount command uaSteam turbine valve opening ubOpening u of water supply valvecIs input into the system
Figure FDA0002842785370000011
Figure FDA0002842785370000012
The extraction flow of the steam turbine is system disturbance f and electric power yaMain steam pressure ybAnd intermediate point enthalpy ycIs output to the system
Figure FDA0002842785370000013
Carrying out an excitation test to obtain dynamic data of system operation;
(12) selecting a sampling period TsIdentifying a furnace system prediction model based on the obtained data;
(13) through model recursion, output sequence of the system in a future period of time is obtained
Figure FDA0002842785370000021
Expressed as a sequence of future input increments
Figure FDA0002842785370000022
And perturbation increment sequence
Figure FDA0002842785370000023
A function of (a); in the formula, NyTo predict the time domain, NuIn order to control the time domain,
Figure FDA0002842785370000024
respectively representing time k to k + Ny-an estimate of the system output at time 1;
Figure FDA0002842785370000025
respectively representing time k to k + Nu-1 input increase of the time systemAn amount;
Figure FDA0002842785370000026
respectively representing time k to k + Nu-1 a disturbance increment of the system at time instant; suppose that the control and perturbation acts on NuRemain unchanged after the moment, i.e.
Figure FDA0002842785370000027
Figure FDA0002842785370000028
(14) Taking into account performance indicators
Figure FDA0002842785370000029
Wherein Q isfAnd RfIs a weight matrix for adjusting the quality of input/output control,
Figure FDA00028427853700000210
rfis the future NyThe sequence of set points that the system wants to reach at the moment,
Figure FDA00028427853700000211
Figure FDA00028427853700000212
respectively representing time k to k + Ny-1 time system set point;
at each sampling instant, the following input amplitude and rate constraints are considered:
Figure FDA00028427853700000213
Figure FDA00028427853700000214
wherein u isminFor lower constraint limits of control action, ukFor the control of the current time k, umaxFor the upper constraint limit of the control action, Δ uminFor controlling the lower bound of the action increment, Δ umaxOptimizing the performance index for the constraint upper limit of the control action increment to obtain the optimal control sequence, and adding the first element u to the optimal control sequencekActing on the engine furnace object of the coal-fired power plant.
3. Post combustion CO according to claim 12The coordinated prediction control method for the capture coal-fired power generation system is characterized in that in the step (2), CO is combusted through chemical adsorption2The design of a predictive controller of the trapping system comprises the following specific steps:
(21) at lean solution flow rate udSteam extraction flow u of steam turbineeIs input into the system
Figure FDA0002842785370000031
The flue gas flow is system disturbance g, CO2Trapping rate ydReboiler temperature yeIs output to the system
Figure FDA0002842785370000032
Carrying out an excitation test to obtain dynamic data of system operation;
(22) selecting a sampling period TsIdentifying a capture system prediction model based on the obtained data;
(23) through model recursion, output sequence of the system in a future period of time is obtained
Figure FDA0002842785370000033
Expressed as a sequence of future input increments
Figure FDA0002842785370000034
And perturbation increment sequence
Figure FDA0002842785370000035
A function of (a); in the formula, NyTo predict the time domain, NuIs a control time domain;
Figure FDA0002842785370000036
respectively representing time k to k + Ny-an estimate of the system output at time 1;
Figure FDA0002842785370000037
respectively representing time k to k + Nu-1 input increments of the system at time;
Figure FDA0002842785370000038
respectively representing time k to k + Nu-1 a disturbance increment of the system at time instant; suppose that the control and perturbation acts on NuRemain unchanged after the moment, i.e.
Figure FDA0002842785370000039
Figure FDA00028427853700000310
(24) Taking into account performance indicators
Figure FDA00028427853700000311
Wherein Q isfAnd RfIs a weight matrix for adjusting the quality of input/output control,
Figure FDA00028427853700000312
rfis the future NyThe sequence of set points that the system wants to reach at the moment,
Figure FDA00028427853700000313
Figure FDA00028427853700000314
respectively representing time k to k + Ny-1 time instantSetting a system value;
at each sampling instant, the following input amplitude and rate constraints are considered:
Figure FDA00028427853700000315
Figure FDA00028427853700000316
wherein u isminFor lower constraint limits of control action, ukFor the control of the current time k, umaxFor the upper constraint limit of the control action, Δ uminFor controlling the lower bound of the action increment, Δ umaxOptimizing the performance index for the constraint upper limit of the control action increment to obtain the optimal control sequence, and adding the first element u to the optimal control sequencekActing on CO2The system object is captured.
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