CN105446137A - Thermal power generating unit ammonia spraying automatic control method and thermal power generating unit ammonia spraying automatic control system capable of eliminating large hysteresis quality - Google Patents

Thermal power generating unit ammonia spraying automatic control method and thermal power generating unit ammonia spraying automatic control system capable of eliminating large hysteresis quality Download PDF

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Publication number
CN105446137A
CN105446137A CN201510938812.5A CN201510938812A CN105446137A CN 105446137 A CN105446137 A CN 105446137A CN 201510938812 A CN201510938812 A CN 201510938812A CN 105446137 A CN105446137 A CN 105446137A
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China
Prior art keywords
adder
pid controller
generating unit
controlled device
power generating
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CN201510938812.5A
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Chinese (zh)
Inventor
高嵩
林波
李军
李克雷
韩英昆
于庆彬
庞向坤
姚常青
周长来
孟祥荣
李昌卫
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State Grid Corp of China SGCC
Electric Power Research Institute of State Grid Shandong Electric Power Co Ltd
Shandong Zhongshi Yitong Group Co Ltd
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State Grid Corp of China SGCC
Electric Power Research Institute of State Grid Shandong Electric Power Co Ltd
Shandong Zhongshi Yitong Group Co Ltd
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Application filed by State Grid Corp of China SGCC, Electric Power Research Institute of State Grid Shandong Electric Power Co Ltd, Shandong Zhongshi Yitong Group Co Ltd filed Critical State Grid Corp of China SGCC
Priority to CN201510938812.5A priority Critical patent/CN105446137A/en
Publication of CN105446137A publication Critical patent/CN105446137A/en
Pending legal-status Critical Current

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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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  • Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Artificial Intelligence (AREA)
  • Computer Vision & Pattern Recognition (AREA)
  • Evolutionary Computation (AREA)
  • Medical Informatics (AREA)
  • Software Systems (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Automation & Control Theory (AREA)
  • Treating Waste Gases (AREA)
  • Feedback Control In General (AREA)

Abstract

The invention discloses a thermal power generating unit ammonia spraying automatic control method and a thermal power generating unit ammonia spraying automatic control system capable of eliminating large hysteresis quality. A first adder, a second adder, a PID controller, and a controlled object are sequentially and serially connected together, and the output end of the controlled object is connected with the first input end of the third adder. One end of an object model is connected between the PID controller and the controlled object, and the other end is connected with the second input end of the third adder. The output end of the third adder is connected with the first adder. The conventional PID controller can be reserved, and the influence of the large hysteresis quality on the stability of the conventional control scheme can be eliminated, and then the conventional control performance cannot be affected, and the satisfying adjusting index can be acquired by adjusting the PID controller parameters. After the compensation, the pure hysteresis link is outside the closed loop, and then the influence of the pure hysteresis link on the system stability can be eliminated.

Description

A kind of fired power generating unit spray ammonia autocontrol method and system eliminating large time delay
Technical field
The present invention relates to fired power generating unit SCR flue gas denitrification system spray ammonia automatic adjustment technology field, particularly relate to a kind of fired power generating unit spray ammonia autocontrol method and the system of eliminating large time delay.
Background technology
Along with environmental requirement is more and more stricter, the fume emission quality of Large-scale fire-electricity unit is subject to extensive concern.In denitrating flue gas, more use SCR (SCR) method.
Certain fired power generating unit SCR flue gas denitrification system as shown in Figure 1.Ammonia spraying amount is controlled by a flowrate control valve, in stove, ammonia-spraying grid sprays after mixing with diluent air, after fully mixing with inner flue gas of the stove, enter reaction zone, selective catalysis reaction is there is under the effect of catalyzer, NOX in flue gas is converted into harmless nitrogen and water vapor, reaches flue gas cleaning object.In SCR flue gas denitrification system, spray ammonia regulates extremely important automatically.Spray ammonia crosses that I haven't seen you for ages causes NO xdischarge exceeds standard, and spray ammonia is excessive, causes operating cost to be wasted.Therefore, how control accurately ammonia spraying amount to unit safety and economy all significant.
Because apparatus system is huge, chemical time is long, gametic fertility system has the feature of large time delay.Fig. 2 is the spray ammonia automatic control loop that industry spot is commonly used.
In spray ammonia automatic control system, the transport function of PID controller is C (s), and controlled device transport function is P (s), and the transport function not comprising purely retarded part in controlled device is the transport function of controlled device purely retarded part is the closed loop transfer function, of whole control system is
Φ ( s ) = C ( s ) P ( s ) 1 + C ( s ) P ( s ) = C ( s ) P ‾ ( s ) e - θ s 1 + C ( s ) P ‾ ( s ) e - θ s ;
This shows, containing pure lag system in system features equation, it can reduce the stability of system, and current Industry Control scheme more than 90% adopts PID to control, and is difficult to overcome its hysteresis characteristic.Therefore, be necessary to design more excellent automatic control system and strictly control ammonia spraying amount size well.
Summary of the invention
In order to solve the problem, the present invention proposes a kind of fired power generating unit spray ammonia autocontrol method and the system of eliminating large time delay, the method and system compensate single loop PID scheme by building object model, eliminate the impact of object purely retarded on adjusting function, and this scheme can be built by common industrial module, is easy to Project Realization.
For achieving the above object, concrete scheme of the present invention is as follows:
Eliminate a fired power generating unit spray ammonia autocontrol method for large time delay, comprising:
(1) PID controller is according to outlet NO xsetting value exports ammonia spraying amount instruction to controlled device, after controlled device carries out chemical reaction according to the ammonia spraying amount instruction received, obtains the NO exported xmeasured value;
(2) the ammonia spraying amount instruction of PID controller output is successively after ratio module and first-order lag module, produces control signal s 1;
PID controller export ammonia spraying amount instruction successively after ratio module, first-order lag module and purely retarded module, the NO of output valve and outlet xafter measured value does difference, produce control signal s 2;
(3) NO is exported xsetting value and control signal s 2after doing difference, obtain the first control inputs signal r 1;
(4) first control inputs signal r 1with control signal s 1after doing difference, obtain the second control inputs signal r 2;
(5) PID controller is according to the second control inputs signal r 2export ammonia spraying amount instruction to controlled device, after controlled device carries out chemical reaction according to the ammonia spraying amount instruction received, obtain the NO exported xmeasured value;
(6) return step (2) and realize circulation closed-loop control.
The function expression of described ratio module is specially K, and the function expression of first-order lag module is specially the function expression of purely retarded module is specially
Eliminate a system for the fired power generating unit spray ammonia autocontrol method of large time delay, comprising: first adder, second adder, PID controller, controlled device, the 3rd totalizer and object model;
Described first adder, second adder, PID controller and controlled device are sequentially connected in series, and the output terminal of controlled device is connected with the first input end of the 3rd totalizer; One end of described object model is connected between PID controller and controlled device, and the other end is connected with the second input end of the 3rd totalizer; The output terminal of described 3rd totalizer is connected with first adder;
Described object model comprises: the ratio module be sequentially connected in series, first-order lag module and purely retarded module; The output terminal of described first-order lag module is connected to second adder.
The input value of described first adder is respectively outlet NO xthe output valve of setting value and the 3rd totalizer.
The output of described PID controller is ammonia spraying amount instruction, acts on controlled device, after controlled device carries out chemical reaction, generates the NO of outlet x.
Beneficial effect of the present invention:
(1) after over-compensation, pure lag system, outside closed loop, thus eliminating the need the impact of pure lag system on system stability.
(2) remain original PID controller, this control method only eliminates the impact of large time delay on original control program stability, does not affect its original control performance, can obtain satisfied regulating index by adjustment PID controller parameter.
(3) be easy to Project Realization, build three modules of object model: proportional action K, first-order lag module Lag and purely retarded module Delay all can obtain the module of commercialization in the scattered control system of industry spot, directly can call and build.
Accompanying drawing explanation
Fig. 1 is fired power generating unit SCR flue gas denitrification system structural representation;
Fig. 2 is traditional spray ammonia Automatic Control Theory figure;
Fig. 3 is the fired power generating unit spray ammonia Automatic Control Theory figure of elimination large time delay of the present invention.
Embodiment
Below in conjunction with accompanying drawing, the present invention is described in detail:
Eliminate a fired power generating unit spray ammonia autocontrol method for large time delay, its step is:
(1) PID controller is according to outlet NO xsetting value exports ammonia spraying amount instruction to controlled device, after controlled device carries out chemical reaction according to the ammonia spraying amount instruction received, obtains the NO exported xmeasured value;
(2) the ammonia spraying amount instruction of PID controller output is successively after ratio module and first-order lag module, produces control signal s 1;
PID controller export ammonia spraying amount instruction successively after ratio module, first-order lag module and purely retarded module, the NO of output valve and outlet xafter measured value does difference, produce control signal s 2;
(3) NO is exported xsetting value and control signal s 2after doing difference, obtain the first control inputs signal r 1;
(4) first control inputs signal r 1with control signal s 1after doing difference, obtain the second control inputs signal r 2; Send into PID controller and carry out computing;
(5) PID controller is according to the second control inputs signal r 2export ammonia spraying amount instruction to controlled device, after controlled device carries out chemical reaction according to the ammonia spraying amount instruction received, obtain the NO exported xmeasured value;
(6) return step (2) and realize circulation closed-loop control.
Build object model, be made up of three modules: proportional action K, first-order lag module Lag, and purely retarded module Delay.Object model relates generally to three parameters: Proportional coefficient K, first-order lag time constant T 1, and pure delay time constant T 2; These three parameters are relevant with field apparatus characteristic, can adjust according to actual conditions.
Eliminate a fired power generating unit spray ammonia automatic control system for large time delay, comprising: first adder, second adder, PID controller, controlled device, the 3rd totalizer and object model;
First adder, second adder, PID controller and controlled device are sequentially connected in series, and the output terminal of controlled device is connected with the first input end of the 3rd totalizer; One end of described object model is connected between PID controller and controlled device, and the other end is connected with the second input end of the 3rd totalizer; The output terminal of described 3rd totalizer is connected with first adder;
Object model comprises: the ratio module be sequentially connected in series, first-order lag module and purely retarded module; The output terminal of described first-order lag module is connected to second adder.
The input value of first adder is respectively outlet NO xthe output valve of setting value and the 3rd totalizer.The output of PID controller is ammonia spraying amount instruction, acts on controlled device, after controlled device carries out chemical reaction, generates the NO of outlet x.
The closed loop transfer function, of this spray ammonia automatic control system is
Φ ′ ( s ) = = C ( s ) P ‾ ( s ) 1 + C ( s ) P ‾ ( s ) e - θ s ;
As can be seen from the above equation, after over-compensation, pure lag system, outside closed loop, thus eliminating the need the impact of pure lag system on system stability.The shifting theorem of Laplace transformation illustrates e -θ sonly control action has been passed on time-base a time θ, and the transient process of control system and other performance index with plant characteristic are all time identical.
By reference to the accompanying drawings the specific embodiment of the present invention is described although above-mentioned; but not limiting the scope of the invention; one of ordinary skill in the art should be understood that; on the basis of technical scheme of the present invention, those skilled in the art do not need to pay various amendment or distortion that creative work can make still within protection scope of the present invention.

Claims (5)

1. eliminate a fired power generating unit spray ammonia autocontrol method for large time delay, it is characterized in that, comprising:
(1) PID controller is according to outlet NO xsetting value exports ammonia spraying amount instruction to controlled device, after controlled device carries out chemical reaction according to the ammonia spraying amount instruction received, obtains the NO exported xmeasured value;
(2) the ammonia spraying amount instruction of PID controller output is successively after ratio module and first-order lag module, produces control signal s 1;
PID controller export ammonia spraying amount instruction successively after ratio module, first-order lag module and purely retarded module, the NO of output valve and outlet xafter measured value does difference, produce control signal s 2;
(3) NO is exported xsetting value and control signal s 2after doing difference, obtain the first control inputs signal r 1;
(4) first control inputs signal r 1with control signal s 1after doing difference, obtain the second control inputs signal r 2;
(5) PID controller is according to the second control inputs signal r 2export ammonia spraying amount instruction to controlled device, after controlled device carries out chemical reaction according to the ammonia spraying amount instruction received, obtain the NO exported xmeasured value;
(6) return step (2) and realize circulation closed-loop control.
2. a kind of fired power generating unit spray ammonia autocontrol method eliminating large time delay as claimed in claim 1, it is characterized in that, the function expression of described ratio module is specially K, and the function expression of first-order lag module is specially the function expression of purely retarded module is specially
3. realize a system for the fired power generating unit spray ammonia autocontrol method eliminating large time delay described in claim 1, it is characterized in that, comprising: first adder, second adder, PID controller, controlled device, the 3rd totalizer and object model;
Described first adder, second adder, PID controller and controlled device are sequentially connected in series, and the output terminal of controlled device is connected with the first input end of the 3rd totalizer; One end of described object model is connected between PID controller and controlled device, and the other end is connected with the second input end of the 3rd totalizer; The output terminal of described 3rd totalizer is connected with first adder;
Described object model comprises: the ratio module be sequentially connected in series, first-order lag module and purely retarded module; The output terminal of described first-order lag module is connected to second adder.
4. a kind of fired power generating unit spray ammonia automatic control system eliminating large time delay as claimed in claim 1, it is characterized in that, the input value of described first adder is respectively outlet NO xthe output valve of setting value and the 3rd totalizer.
5. a kind of fired power generating unit spray ammonia automatic control system eliminating large time delay as claimed in claim 1, it is characterized in that, the output of described PID controller is ammonia spraying amount instruction, acts on controlled device, after controlled device carries out chemical reaction, generates the NO of outlet x.
CN201510938812.5A 2015-12-15 2015-12-15 Thermal power generating unit ammonia spraying automatic control method and thermal power generating unit ammonia spraying automatic control system capable of eliminating large hysteresis quality Pending CN105446137A (en)

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CN113639204A (en) * 2021-06-28 2021-11-12 厚普清洁能源股份有限公司 Constant-temperature gas supply PID control system and method for LNG fuel ship

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Application publication date: 20160330