CN113110657A - Method, system and medium for controlling hearth pressure and exhaust gas temperature of heating furnace - Google Patents
Method, system and medium for controlling hearth pressure and exhaust gas temperature of heating furnace Download PDFInfo
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Abstract
The invention provides a method for controlling the pressure of a hearth of a heating furnace and the temperature of exhaust smoke, which comprises the steps of determining the input quantity of fuzzy control, wherein the input quantity is the control deviation of the furnace pressure and the control deviation of the exhaust smoke temperature; carrying out fuzzy segmentation on an input space and an output space of the fuzzy control; fuzzification is carried out on the furnace pressure control deviation and the smoke exhaust temperature control deviation; determining a membership function of a fuzzy set; determining a control rule of a fuzzy controller and a fuzzy mapping relation corresponding to the control rule; and determining the control compensation quantity of the smoke exhaust regulating valve and feedforward controlling the hearth pressure of the hot furnace according to the pressure change values of the gas main pipe and the combustion air main pipe in the previous and next times. The invention provides a scheme for dynamically adjusting the weight of feedforward control and feedback control on the furnace pressure of a heating furnace, and autonomously learns a control program for fuzzy control of the furnace pressure; the stability of the hearth pressure is greatly improved, and the safe and stable operation of the heating furnace is ensured; theoretical analysis and practice show that the production energy consumption is reduced.
Description
Technical Field
The invention relates to the technical field of combustion control systems of steel heating furnaces, in particular to a heating furnace hearth pressure and exhaust gas temperature control method based on a variable fuzzy interval.
Background
In the process control of the heating furnace, the controlled quantities are as follows: variables such as billet temperature, heating time, air-fuel ratio, furnace temperature and furnace pressure; similarly, there are disturbance factors such as changes in gas pressure and flow rate, changes in air pressure and flow rate, and changes in gas heat value. Therefore, in the heating process of the billet, the temperature of the heated billet needs to be controlled to meet the rolling requirement by controlling variables such as the pressure and flow of air, the pressure and flow of gas, the switch of a burner and the like. Therefore, the heating furnace control process has the characteristics of multivariable and mutual coupling.
As a multi-target control system, the shorter the heating time of the control system is, the smaller the furnace pressure fluctuation is, and the highest production quality is achieved. However, the heat load of the heating furnace is always in a fluctuating state due to various reasons such as a change in the specification of the charged billet, a difference in the temperature of the charged billet, and a difference in the rolling specification. The severe fluctuation of the furnace pressure often causes high energy consumption, increases the generation amount of the iron scale, and is not beneficial to the efficient and stable operation of production.
For a stepping type conventional proportional combustion heating furnace, a feedback control strategy based on pressure detection is often adopted. The control system is characterized in that 1-2 pressure sensors are arranged at the top of the heating furnace, and the opening degree of a smoke exhaust regulating valve of a smoke exhaust main pipe is adjusted in a feedback mode by detecting the pressure of a hearth, so that the aim of stabilizing the furnace pressure is fulfilled. This control method has the following control disadvantages:
1. the heating furnace is a pure lag, nonlinear, time-varying, large-inertia, strong-coupling and multivariable control system, and feedback adjustment is performed on the smoke exhaust adjusting valve according to the detected furnace pressure, so that the control effect cannot be immediately displayed, and the condition of control imbalance is easily caused.
2. Frequent adjustment of the smoke exhaust regulating valve is very obvious in equipment loss, the equipment replacement period is shortened, and high requirements are provided for operation, maintenance and protection work.
3. The control system adopts a PID control mode for adjustment, and PID control often generates different overshoot and system steady-state errors under different working conditions, so that the control stability of the furnace pressure is further reduced.
4. When a single detection target is adopted, if the pressure sensor fails, the whole control system cannot perform feedback adjustment, and great control hidden danger exists.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a method, a system and a medium for controlling the hearth pressure and the exhaust gas temperature of a heating furnace.
The invention provides a method for controlling the hearth pressure and the exhaust gas temperature of a heating furnace, which comprises the following steps of:
step 1: determining fuzzy control input quantity, wherein the input quantity is furnace pressure control deviation and smoke exhaust temperature control deviation;
step 2: carrying out fuzzy segmentation on an input space and an output space of the fuzzy control;
and step 3: fuzzification is carried out on the furnace pressure control deviation and the smoke exhaust temperature control deviation;
and 4, step 4: determining a membership function of a fuzzy set;
and 5: determining a control rule of a fuzzy controller and a fuzzy mapping relation corresponding to the control rule;
step 6: under the condition that the smoke temperature is normal, the control compensation quantity of the smoke exhaust regulating valve is determined according to the pressure change value of the gas main pipe and the pressure change value of the combustion air main pipe in the previous and next times, the pressure of the hearth of the hot furnace is controlled in a feedforward mode, and when the smoke temperature is ultrahigh, the smoke exhaust temperature is taken as a control target, and the pressure of the hearth of the hot furnace is adjusted in a feedback mode.
Preferably, the step 1 comprises the steps of:
step 1.1: the target furnace pressure PFt is 20Pa, and the target smoke exhaust temperature TSt is 200 ℃;
step 1.2: determining control deviation DPF and DTS according to the actual furnace pressure PFc and the actual exhaust smoke temperature TSc;
DPF＝PFt-PFc；
DTS＝TSt-TSc；
the output is a target control weight c, the target control weight is a real number between 0 and 1, and represents a feedforward control target value correction coefficient, and the exhaust gas temperature is controlled according to the corrected target exhaust gas temperature RTSt ═ TSt + (1-c) × DTS.
Preferably, the step 2 includes:
the input in the control rule of the fuzzy controller and the language variable of the premise form a fuzzy input space, and the language variable of the conclusion forms a fuzzy output space; the value of the language variable is a group of fuzzy language names and forms a set of language names; the fuzzy language names correspond to the fuzzy sets one by one; for each linguistic variable, fuzzy sets of values of the linguistic variables have the same discourse domain, fuzzy segmentation is to determine the number of fuzzy language names of the values of each linguistic variable, and the number of the fuzzy segmentation determines the refinement degree of fuzzy control; the input and output space of the furnace pressure fuzzy control is divided into negative large NB, negative small NS, zero ZR, positive small PS and positive large PB.
Preferably, the step 3 comprises the steps of:
step 3.1: calculating difference statistical distribution parameters mu and sigma;
step 3.2: cumulative density function according to normal distribution:
step 3.3: carrying out threshold value subdivision again by utilizing the calculated 4 x values;
step 3.4: and solving the final discourse domain interval after the change.
Preferably, the step 4 comprises the steps of:
the membership function of the input variables DPF and DTS is a triangular membership function;
the NB triangular membership function relation of the DPF is as follows:
the triangular membership function relation of the NS of the DPF is as follows:
preferably, in step 5, when the DPF is PB, the actual furnace pressure control deviation is "positive large", the DTS is NS, and the actual exhaust gas temperature control deviation is "negative small", the fuzzy specification output is 0.9, and the control should be performed by using the feedforward control as the main control target and using the minimum amount for feedback adjustment of the exhaust gas temperature; the target furnace pressure is controlled in accordance with the corrected target furnace pressure RPFt (PFt + c) DPF, and the exhaust gas temperature is controlled in accordance with the corrected target exhaust gas temperature RTSt (TSt + (1-c) DTS).
The invention also provides a heating furnace hearth pressure and exhaust gas temperature control system, which comprises the following modules:
module M1: determining fuzzy control input quantity, wherein the input quantity is furnace pressure control deviation and smoke exhaust temperature control deviation;
module M2: carrying out fuzzy segmentation on an input space and an output space of the fuzzy control;
module M3: fuzzification is carried out on the furnace pressure control deviation and the smoke exhaust temperature control deviation;
module M4: determining a membership function of a fuzzy set;
module M5: determining a control rule of a fuzzy controller and a fuzzy mapping relation corresponding to the control rule;
module M6: under the condition that the smoke temperature is normal, the control compensation quantity of the smoke exhaust regulating valve is determined according to the pressure change value of the gas main pipe and the pressure change value of the combustion air main pipe in the previous and next times, the pressure of the hearth of the hot furnace is controlled in a feedforward mode, and when the smoke temperature is ultrahigh, the smoke exhaust temperature is taken as a control target, and the pressure of the hearth of the hot furnace is adjusted in a feedback mode.
Preferably, the module M1 includes the following modules:
module M1.1: the target furnace pressure PFt is 20Pa, and the target smoke exhaust temperature TSt is 200 ℃;
module M1.2: determining control deviation DPF and DTS according to the actual furnace pressure PFc and the actual exhaust smoke temperature TSc;
DPF＝PFt-PFc；
DTS＝TSt-TSc；
the output is a target control weight c, the target control weight is a real number between 0 and 1, and represents a feedforward control target value correction coefficient, and the exhaust gas temperature is controlled according to the corrected target exhaust gas temperature RTSt ═ TSt + (1-c) × DTS.
The module step 2 comprises:
the input in the control rule of the fuzzy controller and the language variable of the premise form a fuzzy input space, and the language variable of the conclusion forms a fuzzy output space; the value of the language variable is a group of fuzzy language names and forms a set of language names; the fuzzy language names correspond to the fuzzy sets one by one; for each linguistic variable, fuzzy sets of values of the linguistic variables have the same discourse domain, fuzzy segmentation is to determine the number of fuzzy language names of the values of each linguistic variable, and the number of the fuzzy segmentation determines the refinement degree of fuzzy control; the input and output space of the furnace pressure fuzzy control is divided into negative large NB, negative small NS, zero ZR, positive small PS and positive large PB.
Preferably, the module M3 includes the following modules:
module M3.1: calculating difference statistical distribution parameters mu and sigma;
module M3.2: cumulative density function according to normal distribution:
module M3.3: carrying out threshold value subdivision again by utilizing the calculated 4 x values;
module M3.4: and solving the final discourse domain interval after the change.
The module M4 includes the following modules:
the membership function of the input variables DPF and DTS is a triangular membership function;
the NB triangular membership function relation of the DPF is as follows:
the triangular membership function relation of the NS of the DPF is as follows:
when the DPF is PB, the actual furnace pressure control deviation is positive and the DTS is NS, and the actual exhaust gas temperature control deviation is negative and small, the module M5 outputs a fuzzy specification of 0.9, and controls the feedback control to be the main control target, and the minimum amount is used for the feedback adjustment of the exhaust gas temperature; the target furnace pressure is controlled in accordance with the corrected target furnace pressure RPFt (PFt + c) DPF, and the exhaust gas temperature is controlled in accordance with the corrected target exhaust gas temperature RTSt (TSt + (1-c) DTS).
The invention also provides a computer-readable storage medium having stored thereon a computer program which, when being executed by a processor, carries out the steps of the method as set forth above.
Compared with the prior art, the invention has the following beneficial effects:
1. the invention provides a scheme for dynamically adjusting the weight of feedforward control and feedback control on the furnace pressure of a heating furnace, and autonomously learns a control program for fuzzy control of the furnace pressure; the stability of the hearth pressure is greatly improved, and the safe and stable operation of the heating furnace is ensured; theoretical analysis and practice show that the method completely meets the requirements of the production process and reduces the production energy consumption.
2. The pressure fluctuation of the hearth is small, the furnace pressure is basically and stably controlled within +/-10% of a target, and the smoke exhaust temperature is lower than the target smoke exhaust temperature; the slag removal cycle is reduced to 5 times from 6 times per year; the fuel consumption of each ton of steel is saved, the fuel consumption of each ton of steel is reduced by about 5 percent each year, and the economic benefit is obvious.
Drawings
Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:
FIG. 1 is a block diagram of a feedback mode furnace pressure control system of the present invention;
FIG. 2 is a block diagram of a feed forward mode furnace pressure control system of the present invention;
FIG. 3 is a graph of membership relationships according to the present invention;
FIG. 4 is a block diagram of the multi-objective constraint programming control system for furnace pressure and flue gas temperature of the present invention.
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that it would be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit of the invention. All falling within the scope of the present invention.
The invention provides a method for controlling the hearth pressure and the exhaust gas temperature of a heating furnace based on a variable fuzzy interval, wherein when the pressure in the heating furnace is too low, cold air is often caused to enter the furnace through a furnace opening, so that a large amount of fuel is wasted; on the contrary, if the furnace pressure is too high, the hot gas in the furnace is sprayed out through the furnace mouth, and the heat loss is also caused, thereby causing unnecessary fuel waste. Therefore, the furnace pressure must be closely monitored in each control part of the heating furnace to ensure the stability of the furnace pressure; during control, the furnace pressure can be controlled in a feedforward control mode, and a pressure detection point is arranged at the top of the heating furnace; however, when the temperature of the exhaust gas is too high, the temperature of the heating furnace is also higher, and at the moment, if the temperature reaches the heat-resisting limit of the furnace body, the service life of the heating furnace is seriously influenced, so that when the temperature of the flue gas of the heating furnace is too high, the main contradiction becomes that the temperature of the flue gas is too high, and the fluctuation change of the furnace pressure becomes a secondary contradiction; therefore, effective measures must be taken as soon as possible to bring the smoke temperature back within the normal range.
Referring to fig. 1, in the furnace pressure feedback control method, the furnace pressure is feedback-adjusted with the exhaust gas temperature as a control target. The smoke temperature is controlled by controlling the opening of the smoke exhaust regulating valve.
Referring to fig. 2, in the furnace pressure feedforward control mode, the control compensation amount DC of the smoke exhaust regulating valve is determined according to the pressure change value DPG of the gas main pipe and the pressure change value DPA of the combustion air main pipe twice before and after, and can be represented by the following formula
DC ═ kgas DPG + kair DPA, where kgas and kair squares represent the coal pressure compensation coefficient and the air pressure compensation coefficient, respectively.
When the heating furnace is produced, the control of the furnace pressure and the exhaust gas temperature is always considered, different control weights are required to be distributed for single feedforward and feedback control at the moment, and the size of the weight is always dependent on the operation experience of an operator, so that adverse effects and potential safety hazards are brought to the control effect of the system; therefore, a feedforward and feedback pressure control selection controller can be designed, the change condition of the furnace pressure and the continuity of the furnace pressure control need to be fully considered, and the furnace pressure cannot fluctuate greatly when the controller is switched.
In order to ensure the continuity and stability of furnace pressure control, the idea of fuzzy theory is adopted, and the control requirements of the exhaust gas temperature and the furnace pressure are considered; the control system combines the specific conditions of the pressure of the gas main pipe and the temperature of the exhaust smoke, fuzzy calculation is carried out by utilizing the difference value of the target furnace pressure and the actual furnace pressure and the difference value of the target exhaust smoke temperature and the actual exhaust smoke temperature, and the opening degree set value and the compensation value of the corresponding exhaust smoke regulating valve of the control system are given when different furnace pressures and different exhaust smoke temperatures are adopted.
The specific control process comprises the following steps:
step 1: and determining input and output quantities, wherein the input quantities are the furnace pressure control deviation and the exhaust smoke temperature control deviation.
Step 1.1: the target furnace pressure PFt is 20Pa, and the target flue gas temperature TSt is 200 ℃.
Step 1.2: determining control deviation DPF and DTS according to the actual furnace pressure PFc and the actual exhaust smoke temperature TSc;
DPF＝PFt-PFc；
DTS＝TSt–TSc；
the output quantity is a target control weight c; c is a real number between 0 and 1, and represents a feedforward control target value correction coefficient, such as: when c is 0.8, the actual control is performed in accordance with the corrected target furnace pressure RPFt (PFt + c) DPF, and in the same manner, the exhaust gas temperature is controlled in accordance with the corrected target exhaust gas temperature RTSt (TSt + (1-c) DTS.
Step 2: fuzzy segmentation of input and output space.
The inputs in the control rules of the fuzzy controller and the linguistic variables of the premises constitute a fuzzy input space and the linguistic variables of the conclusions constitute a fuzzy output space. Each linguistic variable takes the value of a group of fuzzy linguistic names, and the fuzzy linguistic names form a set of linguistic names; each fuzzy language name corresponds to a fuzzy set; for each linguistic variable, fuzzy sets of values of the linguistic variables have the same discourse domain, fuzzy segmentation is to determine the number of fuzzy language names of the values of each linguistic variable, and the number of the fuzzy segmentation determines the refinement degree of fuzzy control; the invention divides the input and output space of furnace pressure fuzzy control into the following five grades: negative large NB, negative small NS, zero ZR, positive small PS, and positive large PB.
And step 3: blurring of the precise amount.
The DPF and DTS acquired in the fuzzy control process are continuous variable quantities, and the variable quantities must be fuzzified to meet the requirements of fuzzy control, and the process of converting digital quantities into fuzzy quantities is called fuzzification; in general, when converting the exact quantity x between the [ a, b ] intervals into discrete quantities y between the [ -n, m ] intervals, the formula y ═ m + n) [ x- (a + b)/2]/(b-a) is used; in the fuzzy controller designed by the invention, the domain of discourse range of the DPF is initially set to be [ -10,10], the domain of the DTS is initially set to be [ -10,10], and the domain of the c is [0,1 ]. For example, when the actual furnace pressure PFc is 70Pa and the fluctuation range of the furnace pressure is 0 to 100Pa, the blurring amount yPFc corresponding thereto is (m + n) [ x- (a + b)/2]/(b-a) ═ 10+10) [70- (0+100)/2]/(100-0) ═ 4 after the blurring rule processing. However, because the heating furnace is in a long-time continuous operation state, the operation condition of the heating furnace changes, and the control effect of the single domain-of-discourse interval in the later operation stage of the system is very undesirable, the domain-of-discourse interval needs to be determined in a time-series-based mode; and establishing a normal distribution form based on the DPF by using n DPF values before the current time, wherein n is greater than 30, and dividing a domain corresponding to the current condition.
Calculating difference statistical distribution parameters mu and sigma;
cumulative density function according to normal distribution:
calculating the threshold corresponding to 5 domains, and obtaining the value of x when F (x, mu, sigma) is [0.2,0.4,0.6,0.8] respectively;
carrying out threshold value subdivision again by utilizing the calculated 4 x values; and solving the final discourse domain interval after the change.
And 4, step 4: membership functions of the fuzzy sets are determined.
Referring to fig. 3, the membership functions of the input variables DPF and DTS adopted in the present invention are both triangular membership functions; for each domain of DPF and DTS, the same trigonometric function relation is adopted, namely the NB domain of DPF has a trigonometric membership function relation of
And the relation of the triangular membership function of NS is
When the fuzzified DPF is 2.9, it can be found that the value of the DPF belonging to the domain NB is 0.87, the value of the DPF belonging to the domain NS is 2.46, the values of the DPF belonging to ZR, PS and PB are all 0, and the domain in which the maximum value of all the values is located is taken as the final DPF output domain, and the DPF output domain is NS.
And 5: a control rule of the fuzzy controller is determined.
Considering the variation process of DPF and DTS, there are five cases of negative big NB, negative small NS, zero ZR, positive small PS and positive big PB, and the following control strategy is established:
TABLE 1 control policy Table
The fuzzy mapping relation corresponding to the rule is as follows:
1.if(DPF＝NB)and(DTS＝NB)then(c＝0.5)
2.if(DPF＝NB)and(DTS＝NS)then(c＝0.3)
3.if(DPF＝NB)and(DTS＝ZR)then(c＝0.2)
4.if(DPF＝NB)and(DTS＝PS)then(c＝0.1)
5.if(DPF＝NB)and(DTS＝PB)then(c＝0)
6.if(DPF＝NS)and(DTS＝NB)then(c＝0.7)
7.if(DPF＝NS)and(DTS＝NS)then(c＝0.5)
8.if(DPF＝NS)and(DTS＝ZR)then(c＝0.3)
9.if(DPF＝NS)and(DTS＝PS)then(c＝0.2)
10.if(DPF＝NS)and(DTS＝PB)then(c＝0.1)
11.if(DPF＝ZR)and(DTS＝NB)then(c＝0.8)
12.if(DPF＝ZR)and(DTS＝NS)then(c＝0.7)
13.if(DPF＝ZR)and(DTS＝ZR)then(c＝0.5)
14.if(DPF＝ZR)and(DTS＝PS)then(c＝0.3)
15.if(DPF＝ZR)and(DTS＝PB)then(c＝0.2)
16.if(DPF＝PS)and(DTS＝NB)then(c＝0.9)
17.if(DPF＝PS)and(DTS＝NS)then(c＝0.8)
18.if(DPF＝PS)and(DTS＝ZR)then(c＝0.7)
19.if(DPF＝PS)and(DTS＝PS)then(c＝0.5)
20.if(DPF＝PS)and(DTS＝PB)then(c＝0.3)
21.if(DPF＝PB)and(DTS＝NB)then(c＝1)
22.if(DPF＝PB)and(DTS＝NS)then(c＝0.9)
23.if(DPF＝PB)and(DTS＝ZR)then(c＝0.8)
24.if(DPF＝PB)and(DTS＝PS)then(c＝0.7)
25.if(DPF＝PB)and(DTS＝PB)then(c＝0.5)
the weights for feedforward and feedback control can be determined by the fuzzy specification map. For example, when DPF is PB, that is, the actual furnace pressure control deviation is "positive" and DTS is NS, that is, the actual exhaust gas temperature control deviation is "negative" the fuzzy specification output is 0.9, that is, the control should be feedback-adjusted only by a very small amount with the feedforward control as the main control target; that is, the target furnace pressure is controlled in accordance with the corrected target furnace pressure RPFt (PFt + c) DPF, and the flue gas temperature is controlled in accordance with the corrected target flue gas temperature RTSt (TSt + (1-c) DTS in the same manner.
When DPF is NB and DTS is PB, the system output c is 0; this means that when the furnace pressure control deviation is "negative large" and the flue gas temperature control deviation is "positive large", only the flue gas temperature is controlled, which corresponds to a control means using only feedback control.
Referring to fig. 4, the method can be used for seamless switching between feedforward control and feedback control, and when the smoke temperature is normal, the opening degree of the smoke exhaust regulating valve is compensated, and the feedforward control mode is selected for control, so that the furnace pressure is controlled to be stable; when the smoke temperature is ultrahigh, the smoke temperature is controlled by selecting a feedback control mode, so that the smoke temperature can be recovered to the requirement allowed by the process as soon as possible; however, in most cases, there are cases where the feedforward control and the feedback control need to be adjusted at the same time, and at this time, the weights of the feedforward control and the feedback control need to be reasonably distributed so that the furnace pressure and the flue gas temperature are kept stable.
The invention provides a heating furnace hearth pressure and exhaust gas temperature control method based on a variable fuzzy interval, which provides a scheme for dynamically adjusting feedforward control and feedback control weight of the furnace pressure of a heating furnace, and autonomously learns a control program for fuzzy control of the furnace pressure; the stability of the hearth pressure is greatly improved, and the safe and stable operation of the heating furnace is ensured; theoretical analysis and practice show that the method completely meets the requirements of the production process and reduces the production energy consumption.
The invention has small furnace pressure fluctuation, basically stably controls the furnace pressure within +/-10% of a target, and has the smoke discharge temperature lower than the target smoke discharge temperature; the slag removal cycle is reduced to 5 times from 6 times per year; the fuel consumption of ton steel is saved, the fuel consumption of ton steel is reduced by about 5 percent every year, and the economic benefit is obvious.
The invention also provides a heating furnace hearth pressure and exhaust gas temperature control system, which comprises the following modules: module M1: determining fuzzy control input quantity, wherein the input quantity is furnace pressure control deviation and smoke exhaust temperature control deviation; module M1 includes the following modules: module M1.1: the target furnace pressure PFt is 20Pa, and the target smoke exhaust temperature TSt is 200 ℃; module M1.2: determining control deviation DPF and DTS according to the actual furnace pressure PFc and the actual exhaust smoke temperature TSc; DPF is PFt-PFc; DTS-TSc; the output is a target control weight c, the target control weight is a real number between 0 and 1, and represents a feedforward control target value correction coefficient, and the exhaust gas temperature is controlled according to the corrected target exhaust gas temperature RTSt ═ TSt + (1-c) × DTS.
Module M2: carrying out fuzzy segmentation on an input space and an output space of the fuzzy control; the module step 2 comprises:
the input in the control rule of the fuzzy controller and the language variable of the premise form a fuzzy input space, and the language variable of the conclusion forms a fuzzy output space; the value of the language variable is a group of fuzzy language names and forms a set of language names; the fuzzy language names correspond to the fuzzy sets one by one; for each linguistic variable, fuzzy sets of values of the linguistic variables have the same discourse domain, fuzzy segmentation is to determine the number of fuzzy language names of the values of each linguistic variable, and the number of the fuzzy segmentation determines the refinement degree of fuzzy control; the input and output space of the furnace pressure fuzzy control is divided into negative large NB, negative small NS, zero ZR, positive small PS and positive large PB.
Module M3: fuzzification is carried out on the furnace pressure control deviation and the smoke exhaust temperature control deviation; module M3 includes the following modules: module M3.1: calculating difference statistical distribution parameters mu and sigma; module M3.2: cumulative density function according to normal distribution:
calculating the threshold corresponding to 5 domains of discourse, and when F (x, mu, sigma) is [0.2,0.4,0.6,0.8 respectively]When the value of x is obtained; module M3.3: carrying out threshold value subdivision again by utilizing the calculated 4 x values; module M3.4: and solving the final discourse domain interval after the change.
Module M4: determining a membership function of a fuzzy set; module M4 includes the following modules: the membership function of the input variables DPF and DTS is a triangular membership function; the NB triangular membership function relation of the DPF is as follows:
the triangular membership function relation of the NS of the DPF is as follows:
module M5: determining a control rule of a fuzzy controller and a fuzzy mapping relation corresponding to the control rule; when the DPF is PB, the actual furnace pressure control deviation is "positive large", the DTS is NS, and the actual exhaust gas temperature control deviation is "negative small", the module M5 outputs a fuzzy rule of 0.9, and controls the control to feedback-adjust the exhaust gas temperature by a very small amount while the feedforward control is the main control target; the target furnace pressure is controlled in accordance with the corrected target furnace pressure RPFt (PFt + c) DPF, and the exhaust gas temperature is controlled in accordance with the corrected target exhaust gas temperature RTSt (TSt + (1-c) DTS).
Module M6: under the condition that the smoke temperature is normal, the control compensation quantity of the smoke exhaust regulating valve is determined according to the pressure change value of the gas main pipe and the pressure change value of the combustion air main pipe in the previous and next times, the pressure of the hearth of the hot furnace is controlled in a feedforward mode, and when the smoke temperature is ultrahigh, the smoke exhaust temperature is taken as a control target, and the pressure of the hearth of the hot furnace is adjusted in a feedback mode.
The invention also provides a computer-readable storage medium having a computer program stored thereon, which, when being executed by a processor, carries out the steps of the method as described above.
Those skilled in the art will appreciate that, in addition to implementing the system and its various devices, modules, units provided by the present invention as pure computer readable program code, the system and its various devices, modules, units provided by the present invention can be fully implemented by logically programming method steps in such a manner as to implement the same functions in the form of logic gates, switches, application specific integrated circuits, programmable logic controllers, embedded microcontrollers and the like. Therefore, the system and various devices, modules and units thereof provided by the invention can be regarded as a hardware component, and the devices, modules and units included in the system for realizing various functions can also be regarded as structures in the hardware component; means, modules, units for performing the various functions may also be regarded as structures within both software modules and hardware components for performing the method.
The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention. The embodiments and features of the embodiments of the present application may be combined with each other arbitrarily without conflict.
Claims (10)
1. A method for controlling the hearth pressure and the exhaust gas temperature of a heating furnace is characterized by comprising the following steps:
step 1: determining fuzzy control input quantity, wherein the input quantity is furnace pressure control deviation and smoke exhaust temperature control deviation;
step 2: carrying out fuzzy segmentation on an input space and an output space of the fuzzy control;
and step 3: fuzzification is carried out on the furnace pressure control deviation and the smoke exhaust temperature control deviation;
and 4, step 4: determining a membership function of a fuzzy set;
and 5: determining a control rule of a fuzzy controller and a fuzzy mapping relation corresponding to the control rule;
step 6: under the condition that the smoke temperature is normal, the control compensation quantity of the smoke exhaust regulating valve is determined according to the pressure change value of the gas main pipe and the pressure change value of the combustion air main pipe twice, the pressure of the hearth of the hot furnace is controlled in a feedforward mode, and when the smoke temperature is ultrahigh, the pressure of the hearth of the hot furnace is adjusted in a feedback mode by taking the smoke exhaust temperature as a control target.
2. The method for controlling the furnace pressure and the exhaust gas temperature of the heating furnace according to claim 1, wherein the step 1 comprises the following steps:
step 1.1: the target furnace pressure PFt is 20Pa, and the target smoke exhaust temperature TSt is 200 ℃;
step 1.2: determining control deviation DPF and DTS according to the actual furnace pressure PFc and the actual exhaust smoke temperature TSc;
DPF＝PFt-PFc；
DTS＝TSt-TSc；
the output is a target control weight c, the target control weight is a real number between 0 and 1, and represents a feedforward control target value correction coefficient, and the exhaust gas temperature is controlled according to the corrected target exhaust gas temperature RTSt ═ TSt + (1-c) × DTS.
3. The method for controlling the furnace pressure and the exhaust gas temperature of the heating furnace according to claim 1, wherein the step 2 comprises:
the input in the control rule of the fuzzy controller and the language variable of the premise form a fuzzy input space, and the language variable of the conclusion forms a fuzzy output space; the value of the language variable is a group of fuzzy language names and forms a set of language names; the fuzzy language names correspond to the fuzzy sets one by one; for each linguistic variable, fuzzy sets of values of the linguistic variables have the same discourse domain, fuzzy segmentation is to determine the number of fuzzy language names of the values of each linguistic variable, and the number of the fuzzy segmentation determines the refinement degree of fuzzy control; the input and output space of the furnace pressure fuzzy control is divided into negative large NB, negative small NS, zero ZR, positive small PS and positive large PB.
4. The method for controlling the furnace pressure and the exhaust gas temperature of the heating furnace according to claim 1, wherein the step 3 comprises the following steps:
step 3.1: calculating difference statistical distribution parameters mu and sigma;
step 3.2: cumulative density function according to normal distribution:
step 3.3: carrying out threshold value subdivision again by utilizing the calculated 4 x values;
step 3.4: and solving the final discourse domain interval after the change.
5. The method for controlling the furnace pressure and the exhaust gas temperature of the heating furnace according to claim 1, wherein the step 4 comprises the following steps:
the membership function of the input variables DPF and DTS is a triangular membership function;
the NB triangular membership function relation of the DPF is as follows:
the triangular membership function relation of the NS of the DPF is as follows:
6. the method according to claim 1, wherein in step 5, when the DPF is PB, the actual furnace pressure control deviation is "positive" and the DTS is NS, and the actual exhaust gas temperature control deviation is "negative" and the fuzzy specification output is 0.9, the control should be based on the feedforward control and the control should be based on the feedback control for the feedback adjustment of the exhaust gas temperature by a very small amount; the target furnace pressure is controlled in accordance with the corrected target furnace pressure RPFt (PFt + c) DPF, and the exhaust gas temperature is controlled in accordance with the corrected target exhaust gas temperature RTSt (TSt + (1-c) DTS).
7. The utility model provides a heating furnace pressure and exhaust gas temperature control system which characterized in that includes following module:
module M1: determining fuzzy control input quantity, wherein the input quantity is furnace pressure control deviation and smoke exhaust temperature control deviation;
module M2: carrying out fuzzy segmentation on an input space and an output space of the fuzzy control;
module M3: fuzzification is carried out on the furnace pressure control deviation and the smoke exhaust temperature control deviation;
module M4: determining a membership function of a fuzzy set;
module M5: determining a control rule of a fuzzy controller and a fuzzy mapping relation corresponding to the control rule;
module M6: under the condition that the smoke temperature is normal, the control compensation quantity of the smoke exhaust regulating valve is determined according to the pressure change value of the gas main pipe and the pressure change value of the combustion air main pipe twice, the pressure of the hearth of the hot furnace is controlled in a feedforward mode, and when the smoke temperature is ultrahigh, the pressure of the hearth of the hot furnace is adjusted in a feedback mode by taking the smoke exhaust temperature as a control target.
8. The furnace pressure and exhaust smoke temperature control system of the heating furnace according to claim 7, wherein the module M1 comprises the following modules:
module M1.1: the target furnace pressure PFt is 20Pa, and the target smoke exhaust temperature TSt is 200 ℃;
module M1.2: determining control deviation DPF and DTS according to the actual furnace pressure PFc and the actual exhaust smoke temperature TSc;
DPF＝PFt-PFc；
DTS＝TSt-TSc；
the output is a target control weight c, the target control weight is a real number between 0 and 1, and represents a feedforward control target value correction coefficient, and the exhaust gas temperature is controlled according to the corrected target exhaust gas temperature RTSt ═ TSt + (1-c) × DTS.
The module step 2 comprises:
the input in the control rule of the fuzzy controller and the language variable of the premise form a fuzzy input space, and the language variable of the conclusion forms a fuzzy output space; the value of the language variable is a group of fuzzy language names and forms a set of language names; the fuzzy language names correspond to the fuzzy sets one by one; for each linguistic variable, fuzzy sets of values of the linguistic variables have the same discourse domain, fuzzy segmentation is to determine the number of fuzzy language names of the values of each linguistic variable, and the number of the fuzzy segmentation determines the refinement degree of fuzzy control; the input and output space of the furnace pressure fuzzy control is divided into negative large NB, negative small NS, zero ZR, positive small PS and positive large PB.
9. The furnace pressure and exhaust smoke temperature control system of the heating furnace according to claim 7, wherein the module M3 comprises the following modules:
module M3.1: calculating difference statistical distribution parameters mu and sigma;
module M3.2: cumulative density function according to normal distribution:
module M3.3: carrying out threshold value subdivision again by utilizing the calculated 4 x values;
module M3.4: and solving the final discourse domain interval after the change.
The module M4 includes the following modules:
the membership function of the input variables DPF and DTS is a triangular membership function;
the NB triangular membership function relation of the DPF is as follows:
the triangular membership function relation of the NS of the DPF is as follows:
when the DPF is PB, the actual furnace pressure control deviation is positive, the DTS is NS, and the actual exhaust gas temperature control deviation is negative, the module M5 outputs a fuzzy specification of 0.9, controls the control that the feedforward control should be the main control target, and adjusts the exhaust gas temperature by the minimum amount of feedback; the target furnace pressure is controlled in accordance with the corrected target furnace pressure RPFt (PFt + c) DPF, and the exhaust gas temperature is controlled in accordance with the corrected target exhaust gas temperature RTSt (TSt + (1-c) DTS).
10. A computer-readable storage medium, in which a computer program is stored which, when being executed by a processor, carries out the steps of the method according to any one of claims 1 to 6.
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