CN104075340B - Low nitrogen burning control method and system based on PLC - Google Patents
Low nitrogen burning control method and system based on PLC Download PDFInfo
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- CN104075340B CN104075340B CN201410341338.3A CN201410341338A CN104075340B CN 104075340 B CN104075340 B CN 104075340B CN 201410341338 A CN201410341338 A CN 201410341338A CN 104075340 B CN104075340 B CN 104075340B
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- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 title claims abstract description 166
- 229910052757 nitrogen Inorganic materials 0.000 title claims abstract description 83
- 238000000034 method Methods 0.000 title claims abstract description 21
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 claims abstract description 105
- 238000002485 combustion reaction Methods 0.000 claims description 20
- 230000010354 integration Effects 0.000 claims description 17
- 239000013256 coordination polymer Substances 0.000 claims description 14
- 238000004891 communication Methods 0.000 claims description 10
- 238000005457 optimization Methods 0.000 abstract description 7
- 239000003245 coal Substances 0.000 description 17
- 238000010586 diagram Methods 0.000 description 11
- 230000008859 change Effects 0.000 description 6
- 150000001875 compounds Chemical class 0.000 description 5
- GQPLMRYTRLFLPF-UHFFFAOYSA-N Nitrous Oxide Chemical class [O-][N+]#N GQPLMRYTRLFLPF-UHFFFAOYSA-N 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 238000012544 monitoring process Methods 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- 230000001419 dependent effect Effects 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 230000006870 function Effects 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 230000001681 protective effect Effects 0.000 description 2
- 238000010298 pulverizing process Methods 0.000 description 2
- 230000002411 adverse Effects 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000002817 coal dust Substances 0.000 description 1
- 238000012937 correction Methods 0.000 description 1
- 238000007405 data analysis Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 230000004069 differentiation Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 239000002803 fossil fuel Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000009897 systematic effect Effects 0.000 description 1
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Abstract
A kind of low nitrogen burning control method based on PLC of disclosure and system.Wherein programmable controller PLC is according to the dcs DCS boiler operating parameter fed back, the low nitrogen burning Controlling model pre-set obtains corresponding secondary air register opening degree instruction and separate type burnout degree SOFA throttle opening instruction and corresponding NOx target value；So that DCS utilizes secondary air register opening degree instruction and SOFA throttle opening instruction that corresponding secondary air register and SOFA air door are controlled；PLC is according to the DCS nitrogen oxides measured value fed back and current NOx target value, it is determined that SOFA air door amount of bias；SOFA air door amount of bias is superposed by PLC with the current SOFA throttle opening instruction obtained from low nitrogen burning Controlling model, to obtain calibrated SOFA throttle opening instruction, in order to DCS utilizes calibrated SOFA throttle opening instruction that SOFA air door is controlled.Thus the low nitrogen burning effectively realizing boiler controls, it is achieved economic and environment-friendly optimization of boiler runs.
Description
Technical field
The present invention relates to boiler optimization Combustion System field, particularly to a kind of low nitrogen burning control method based on PLC and system.
Background technology
Within 2012, national environmental protection portion has put into effect new " fossil-fuel power plant atmospheric pollutant emission standard ", the discharge standard that the clear stipulaties nitrogen oxides of coal-burning power plant (NOx) is strict, domestic coal-burning power plant carried out the low nitrogen burning improvement project for boiler in succession.After low nitrogen burning improvement project completes, obtain desirable low nitrogen burning effect, should consider that boiler efficiency takes into account discharged nitrous oxides again, this just requires must to handle coal dust, secondary wind and separate type burnout degree well simultaneously, and (SeparateOverFireAir is called for short: proportion relation SOFA).
At present, on the coal-fired plant boiler adopting low-NO_x combustion technology, it is generally adopted and regulates the method for primary combustion zone secondary wind and SOFA wind by load instruction and adjust burning, control the discharge of nitrogen oxides, namely set function F (x) by load-air quantity (secondary wind and SOFA wind air quantity) and control the aperture of each air door.The realization of this control mode is realized by the configuration of DCS (DistributedControlSystem, dcs) system standard algorithmic block.
Above-mentioned set function F (x) based on DCS system by load-air quantity and control the mode of air distribution, it is considered to factor only has load, when load is determined, each secondary wind and what SOFA wind air distribution scheme also determined that.Under this control mode, load does not change, but when the factors such as boiler ature of coal, operation of coal pulverizing mills, discharged nitrous oxides change, boiler combustion characteristic also changes therewith, original secondary wind and the inapplicable combustion characteristics now of SOFA wind air distribution scheme, under this control mode, secondary wind and SOFA wind air distribution scheme can not synchronize with boiler combustion characteristic adjustment, cause air distribution scheme not mate with combustion characteristics demand, ultimately result in NOx value discharge and be affected by adverse effect with boiler combustion efficiency.This control mode is the control mode of a kind of extensive style comparatively speaking, does not possess the ability of low nitrogen burning optimum control when factor changes such as boiler ature of coal, operation of coal pulverizing mills, NOx emission.
Summary of the invention
The embodiment of the present invention provides a kind of low nitrogen burning control method based on PLC and system, programmable controller PLC determines corresponding secondary air register opening degree instruction and SOFA air door instruction according to the DCS boiler operating parameter fed back, and according to nitrogen oxides measured value, SOFA air door instruction is modified, thus the low nitrogen burning effectively realizing boiler controls.
According to an aspect of the present invention, it is provided that a kind of low nitrogen burning control method based on PLC, including:
Programmable controller PLC is according to the dcs DCS boiler operating parameter fed back, the low nitrogen burning Controlling model pre-set obtains corresponding secondary air register opening degree instruction and separate type burnout degree SOFA throttle opening instruction and corresponding NOx target value；
Secondary air register opening degree instruction and SOFA throttle opening instruction are sent to DCS by PLC, in order to DCS utilizes secondary air register opening degree instruction and SOFA throttle opening instruction respectively secondary air register and SOFA air door to be controlled；
PLC is according to the DCS nitrogen oxides measured value fed back and current NOx target value, it is determined that SOFA air door amount of bias；
SOFA air door amount of bias is superposed by PLC with the current SOFA throttle opening instruction obtained from low nitrogen burning Controlling model, to obtain calibrated SOFA throttle opening instruction；
Calibrated SOFA throttle opening instruction is sent to DCS by PLC, in order to DCS utilizes calibrated SOFA throttle opening instruction that SOFA air door is controlled.
In one embodiment, PLC is by the DCS boiler operating parameter fed back and nitrogen oxides measured value, and secondary air register opening degree instruction, SOFA throttle opening instruction and SOFA air door amount of bias store in low nitrogen burning Controlling model accordingly, in order to revise and optimize Combustion System model.
In one embodiment, PLC is according to the DCS nitrogen oxides measured value fed back and current NOx target value, it is determined that the step of SOFA air door amount of bias includes:
PLC, when arriving for the n-th calculating cycle, calculates current NOx target value SPnWith current nitrogen oxides measured value PVnDifference Errorn；
Determine ErrornAffiliated interval X and Errorn-1Affiliated interval Y；
Determine corresponding control parameter Z according to interval X and Y, wherein control parameter Z and include proportionality coefficient CP, integral coefficient CI, differential coefficient CD；
The PID calculating for the n-th calculating cycle exports PIDOUTn, wherein PIDOUTn=MP,n+MI,n+MD,n=CP*Errorn+(MI,n-1+CI*Errorn-1)+CD*(PVn-1-PVn), MP,nIt is the PID ratio output in the n-th calculating cycle, MI,nIt is the integration output in the n-th calculating cycle, MD,nIt it is the differential output in the n-th calculating cycle；
By PIDOUTnIt is converted into corresponding SOFA air door amount of bias.
In one embodiment, determine the step of corresponding control parameter Z according to interval X and Y after, also include:
Judge to control whether parameter Z is enable first；
If controlling parameter Z to enable first, then perform to calculate the PID in the n-th calculating cycle and export PIDOUTnStep；
If controlling parameter Z for enable first, then to the integration output M in (n-1)th calculating cycleI,n-1Initialize, MI,n-1=PIDOUTn-1-MP,n+MD,n, then perform to calculate the PID in the n-th calculating cycle and export PIDOUTnStep.
In one embodiment, Errorn=a* (SPn-PVn)+(1-a)*Errorn-1；
Wherein a is filter factor.
In one embodiment, DCS is after receiving the PLC instruction sent, it is judged that currently whether self is in low nitrogen burning control model, and wherein DCS exits low nitrogen burning control model when judging the appearance exception of the communication with PLC；
If currently self being in low nitrogen burning control model, then DCS determine whether the parameter in instruction whether effectively, whether Parameters variation speed in preset range；
If the parameter in instruction is effective and Parameters variation speed is in preset range, then DCS utilizes instruction that corresponding air door is controlled；
If the invalid parameters in instruction, or Parameters variation speed is beyond preset range, the then instruction that the execution of DCS refusal receives.
According to a further aspect in the invention, it is provided that a kind of low nitrogen burning based on PLC controls system, including programmable controller PLC and dcs DCS, wherein:
DCS, for feeding back boiler operating parameter and nitrogen oxides measured value to PLC, when receiving the PLC secondary air register opening degree instruction sent and separate type burnout degree SOFA throttle opening instruction, secondary air register opening degree instruction and SOFA throttle opening instruction is utilized respectively secondary air register and SOFA air door to be controlled；When receiving the PLC calibrated SOFA throttle opening instruction sent, utilize calibrated SOFA throttle opening instruction that SOFA air door is controlled；
PLC, for the boiler operating parameter according to DCS feedback, obtains corresponding secondary air register opening degree instruction and SOFA throttle opening instruction and corresponding NOx target value in the low nitrogen burning Controlling model pre-set；Secondary air register opening degree instruction and SOFA throttle opening instruction are sent to DCS；According to the DCS nitrogen oxides measured value fed back and current NOx target value, it is determined that SOFA air door amount of bias；SOFA air door amount of bias is superposed with the current SOFA throttle opening instruction obtained from low nitrogen burning Controlling model, to obtain calibrated SOFA throttle opening instruction, calibrated SOFA throttle opening instruction is sent to DCS.
In one embodiment, PLC is additionally operable to the DCS boiler operating parameter fed back and nitrogen oxides measured value, and secondary air register opening degree instruction, SOFA throttle opening instruction and SOFA air door amount of bias store in low nitrogen burning Controlling model accordingly, in order to revise and optimize Combustion System model.
In one embodiment, PLC specifically when arriving for the n-th calculating cycle, calculates current NOx target value SPnWith current nitrogen oxides measured value PVnDifference Errorn；Determine ErrornAffiliated interval X and Errorn-1Affiliated interval Y；Determine corresponding control parameter Z according to interval X and Y, wherein control parameter Z and include proportionality coefficient CP, integral coefficient CI, differential coefficient CD；The PID calculating for the n-th calculating cycle exports PIDOUTn, wherein PIDOUTn=MP,n+MI,n+MD,n=CP*Errorn+(MI,n-1+CI*Errorn-1)+CD*(PVn-1-PVn), MP,nIt is the PID ratio output in the n-th calculating cycle, MI,nIt is the integration output in the n-th calculating cycle, MD,nIt it is the differential output in the n-th calculating cycle；By PIDOUTnIt is converted into corresponding SOFA air door amount of bias.
In one embodiment, PLC specifically, after determining corresponding control parameter Z according to interval X and Y, also includes: judge to control whether parameter Z is enable first；If controlling parameter Z to enable first, then perform to calculate the PID in the n-th calculating cycle and export PIDOUTnOperation；If controlling parameter Z for enable first, then to the integration output M in (n-1)th calculating cycleI,n-1Initialize, MI,n-1=PIDOUTn-1-MP,n+MD,n, then perform to calculate the PID in the n-th calculating cycle and export PIDOUTnOperation.
In one embodiment, PLC specifically utilizes formula
Errorn=a* (SPn-PVn)+(1-a)*Errorn-1
Calculate difference Errorn, wherein a is filter factor.
In one embodiment, DCS is additionally operable to after receiving the PLC instruction sent, it is judged that currently whether self is in low nitrogen burning control model, and wherein DCS exits low nitrogen burning control model when judging the appearance exception of the communication with PLC；If currently self being in low nitrogen burning control model, then determine whether the parameter in instruction whether effectively, whether Parameters variation speed in preset range；If the parameter in instruction is effective and Parameters variation speed is in preset range, then utilize instruction that corresponding air door is controlled；If the invalid parameters in instruction, or Parameters variation speed is beyond preset range, the then instruction that refusal execution receives.
The present invention determines corresponding secondary air register opening degree instruction and SOFA air door instruction by PLC according to the DCS boiler operating parameter fed back, and according to nitrogen oxides measured value, SOFA air door instruction is modified, thus the low nitrogen burning effectively realizing boiler controls, it is achieved economic and environment-friendly optimization of boiler runs.
Accompanying drawing explanation
In order to be illustrated more clearly that the embodiment of the present invention or technical scheme of the prior art, the accompanying drawing used required in embodiment or description of the prior art will be briefly described below, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skill in the art, under the premise not paying creative work, it is also possible to obtain other accompanying drawing according to these accompanying drawings.
Fig. 1 is the present invention schematic diagram based on one embodiment of low nitrogen burning control method of PLC.
Fig. 2 is the schematic diagram that present invention determine that SOFA one embodiment of air door amount of bias.
Fig. 3 is the schematic diagram that present invention determine that SOFA air door another embodiment of amount of bias.
Fig. 4 is the present invention schematic diagram based on low nitrogen burning control one embodiment of system of PLC.
Fig. 5 is the schematic diagram that low nitrogen burning of the present invention controls system one embodiment of configuration.
Fig. 6 is the schematic diagram that low nitrogen burning of the present invention control system configures another embodiment.
Detailed description of the invention
Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is clearly and completely described, it is clear that described embodiment is only a part of embodiment of the present invention, rather than whole embodiments.Description only actually at least one exemplary embodiment is illustrative below, never as any restriction to the present invention and application or use.Based on the embodiment in the present invention, the every other embodiment that those of ordinary skill in the art obtain under not making creative work premise, broadly fall into the scope of protection of the invention.
Unless specifically stated otherwise, the parts otherwise set forth in these embodiments and positioned opposite, the numerical expression of step and numerical value do not limit the scope of the invention.
Simultaneously, it should be appreciated that for the ease of describing, the size of the various piece shown in accompanying drawing is not draw according to actual proportionate relationship.
The known technology of person of ordinary skill in the relevant, method and apparatus are likely to be not discussed in detail, but in the appropriate case, described technology, method and apparatus should be considered to authorize a part for description.
Shown here with in all examples discussed, any occurrence should be construed as merely exemplary, not as restriction.Therefore, other example of exemplary embodiment can have different values.
It should also be noted that similar label and letter below figure represent similar terms, therefore, once a certain Xiang Yi accompanying drawing is defined, then it need not be further discussed in accompanying drawing subsequently.
Fig. 1 is the present invention schematic diagram based on one embodiment of low nitrogen burning control method of PLC.As it is shown in figure 1, the method step of the present embodiment is as follows:
Step 101, PLC, according to the DCS boiler operating parameter fed back, obtains corresponding secondary air register opening degree instruction and SOFA throttle opening instruction and corresponding NOx target value in the low nitrogen burning Controlling model pre-set.
Such as, boiler operating parameter can include load, ature of coal, primary air flow, total blast volume (oxygen amount), coal pulverizer compound mode, boiler efficiency etc..DCS can feed back boiler operating parameter at predetermined intervals, it is possible to feeds back in real time.
Preferably, the low nitrogen burning Controlling model pre-set can pass through Thermal-state test fine in a large number and obtain.Such as, discharged nitrous oxides and boiler efficiency can be considered, several atures of coal conventional for power plant and coal pulverizer compound mode, Thermal-state test is carried out under multiple typical loads, obtain NOx target value and secondary wind and SOFA wind optimum air distribution general layout, set up typical condition storehouse with data obtained by experiment for sample point.Based on typical condition, matching controlling curve, it is determined that corresponding secondary wind and SOFA wind opening degree instruction under different operating modes, set up low nitrogen burning Controlling model with this.Thus, PLC from the low nitrogen burning Controlling model pre-set, can obtain the secondary air register opening degree instruction relevant to DCS feedback parameter and SOFA throttle opening instruction.
Step 102, secondary air register opening degree instruction and SOFA throttle opening instruction are sent to DCS by PLC, in order to DCS utilizes secondary air register opening degree instruction and SOFA throttle opening instruction respectively secondary air register and SOFA air door to be controlled.
Step 103, PLC is according to the DCS nitrogen oxides measured value fed back and current NOx target value, it is determined that SOFA air door amount of bias.
Step 104, SOFA air door amount of bias is superposed by PLC with the current SOFA throttle opening instruction obtained from low nitrogen burning Controlling model, to obtain calibrated SOFA throttle opening instruction.
Step 105, calibrated SOFA throttle opening instruction is sent to DCS by PLC, in order to DCS utilizes calibrated SOFA throttle opening instruction that SOFA air door is controlled.
Preferably, the available Modbus agreement of PLC carries out opposing traffic with DCS, and DCS can control main combustion zone secondary air register and SOFA air door by hardwire.
Based on the low nitrogen burning control method based on PLC that the above embodiment of the present invention provides, corresponding secondary air register opening degree instruction and SOFA air door instruction is determined according to the DCS boiler operating parameter fed back by PLC, and according to nitrogen oxides measured value, SOFA air door instruction is modified, thus the low nitrogen burning effectively realizing boiler controls, it is achieved economic and environment-friendly optimization of boiler runs.
In one embodiment, PLC is by the DCS boiler operating parameter fed back and nitrogen oxides measured value, and corresponding secondary air register opening degree instruction, SOFA throttle opening instruction and SOFA air door amount of bias store in low nitrogen burning Controlling model.
Thus, as the course data histories sample of typical condition, typical condition storehouse can be added to during using control program actual motion, further abundant typical condition storehouse, and revise further and optimize Combustion System model.
Such as, system is controlled for the low nitrogen burning of 600MW generating set, in optimizing Combustion System model, 500MW-600MW load is interval, only include 500 megawatts and 600 megawatts of two typical conditions, and for the operating mode between 500 megawatts and 600 megawatts, for instance for the operating mode of 550 megawatts, then need, based on 500 megawatts and 600 megawatts of the two typical conditions, to be determined by matching controlling curve.Owing to there is a certain distance between matched curve and actual condition, the low nitrogen burning that therefore can not effectively realize boiler controls.If going out the canonical process data being now able to represent 550 megawatts of operating modes in actual motion, this course data histories sample can be added in typical condition storehouse.Owing to the precision of actual operating data is better than the result that matched curve obtains, therefore by abundant typical condition storehouse, optimization Combustion System model can be revised further, thus the low nitrogen burning effectively realizing boiler controls.
It is to be noted that the data such as load, ature of coal, coal pulverizer compound mode, oxygen amount, primary air flow, boiler efficiency pass through Modbus mode from DCS system collection, for there is no the unit of ature of coal on-line monitoring, the coal industry analysis of coal data source power plant.For DCS does not characterize the unit of boiler efficiency, it is possible to replaced by other parameter that can characterize boiler economics.
When main combustion zone, secondary wind air distribution is constant, and when SOFA wind air distribution increases, NOx emission can decline, and vice versa.Therefore the method for low nitrogen burning control system adjustment SOFA wind regulates NOx value of feedback and desired value difference.Owing to SOFA air door adjusts, end reaction is a combustion process to NOx emission change, belongs to big delayed time system, if conventionally PID (Proportion, Integration, Differentiation, ratio, integration and differential) regulate, it is extremely difficult to stablizing of system.In order to obtain good control effect, make PID control output relatively more steady, reduce the operating frequency of SOFA wind air door, select the PID of variable element to control to regulate SOFA air door here.Therefore above-mentioned PLC is according to the DCS nitrogen oxides measured value fed back and current NOx target value, it is determined that the step of SOFA air door amount of bias can be as shown in Figure 2:
Step 201, PLC, when arriving for the n-th calculating cycle, calculates current NOx target value SPnWith current nitrogen oxides measured value PVnDifference Errorn。
Preferably, Errorn=a* (SPn-PVn)+(1-a)*Errorn-1, wherein a is filter factor.
Step 202, it is determined that ErrornAffiliated interval X and Errorn-1Affiliated interval Y.
Step 203, determines corresponding control parameter Z according to interval X and Y, wherein controls parameter Z and includes proportionality coefficient CP, integral coefficient CI, differential coefficient CD。
Step 204, the PID calculating for the n-th calculating cycle exports PIDOUTn, wherein PIDOUTn=MP,n+MI,n+MD,n=CP*Errorn+(MI,n-1+CI*Errorn-1)+CD*(PVn-1-PVn), MP,nIt is the PID ratio output in the n-th calculating cycle, MI,nIt is the integration output in the n-th calculating cycle, MD,nIt it is the differential output in the n-th calculating cycle.
Step 205, by PIDOUTnIt is converted into corresponding SOFA air door amount of bias.
The PID of variable element controls with the desired value of NOx emission concentration and the difference of value of feedback for input, passing ratio and integral and calculating and data convert the amount of bias obtaining SOFA air door, and this amount of bias is finally added to and is calculated in the SOFA throttle opening instruction of output by low nitrogen burning Controlling model.Namely according to the desired value of the NOx emission concentration size with the difference of value of feedback and rate of change, can control to carry out on-line tuning to PID, make PID control output more steady, it is possible to reduce the operating frequency of SOFA air door, extend the service life of air door.
Fig. 3 is the schematic diagram that present invention determine that SOFA air door another embodiment of amount of bias.Wherein:
Step 301, PLC, when arriving for the n-th calculating cycle, calculates current NOx target value SPnWith current nitrogen oxides measured value PVnDifference Errorn。
Preferably, Errorn=a* (SPn-PVn)+(1-a)*Errorn-1, wherein a is filter factor.
Step 302, it is determined that ErrornAffiliated interval X and Errorn-1Affiliated interval Y.
Step 303, determines corresponding control parameter Z according to interval X and Y, wherein controls parameter Z and includes proportionality coefficient CP, integral coefficient CI, differential coefficient CD。
Step 304, it is judged that control whether parameter Z is enable first.If controlling parameter Z for enable first, then perform step 305；If controlling parameter Z to enable first, then perform step 306.
Step 305, to the integration output M in (n-1)th calculating cycleI,n-1Initialize, MI,n-1=PIDOUTn-1-MP,n+MD,n。
Step 306, the PID calculating for the n-th calculating cycle exports PIDOUTn, wherein PIDOUTn=MP,n+MI,n+MD,n=CP*Errorn+(MI,n-1+CI*Errorn-1)+CD*(PVn-1- PVn), MP,nIt is the PID ratio output in the n-th calculating cycle, MI,nIt is the integration output in the n-th calculating cycle, MD,nIt it is the differential output in the n-th calculating cycle.
Step 307, by PIDOUTnIt is converted into corresponding SOFA air door amount of bias.
In the present embodiment, when controlling parameter Z for enabling first, by integration output is initialized, it can be ensured that control program is when switching over, and PID output does not have disturbance, in order to ensure the stability of system.
Preferably, in order to improve security of system, communication security relay protective scheme can be increased further.Such as, respectively through monitoring heartbeat signal, DCS and PLC can judge that whether the communication between DCS and PLC is normal.
In one embodiment, DCS is after receiving the PLC instruction sent, it is judged that currently whether self is in low nitrogen burning control model, and wherein DCS exits low nitrogen burning control model when judging the appearance exception of the communication with PLC.If currently self being in low nitrogen burning control model, then DCS determine whether the parameter in instruction whether effectively, whether Parameters variation speed in preset range.If the parameter in instruction is effective and Parameters variation speed is in preset range, then DCS utilizes instruction that corresponding air door is controlled；If the invalid parameters in instruction, or Parameters variation speed is beyond preset range, the then instruction that the execution of DCS refusal receives.If the invalid parameters occurred continuously in instruction, or Parameters variation speed is beyond the situation of preset range, then also can exit low nitrogen burning control model.
In another embodiment, PLC judges whether to be adopted also dependent on effectiveness and the rate of change of the DCS data fed back.
Fig. 4 is the present invention schematic diagram based on low nitrogen burning control one embodiment of system of PLC.As shown in Figure 4, control system based on the low nitrogen burning of PLC and can include PLC401 and DCS402.Wherein:
DCS402, for feeding back boiler operating parameter and nitrogen oxides measured value to PLC401, when receiving the PLC401 secondary air register opening degree instruction sent and SOFA throttle opening instruction, secondary air register opening degree instruction and SOFA throttle opening instruction is utilized respectively secondary air register and SOFA air door to be controlled；When receiving the PLC401 calibrated SOFA throttle opening instruction sent, utilize calibrated SOFA throttle opening instruction that SOFA air door is controlled.
PLC401, for the boiler operating parameter according to DCS402 feedback, obtains corresponding secondary air register opening degree instruction and SOFA throttle opening instruction and corresponding NOx target value in the low nitrogen burning Controlling model pre-set；Secondary air register opening degree instruction and SOFA throttle opening instruction are sent to DCS402；According to the DCS402 nitrogen oxides measured value fed back and current NOx target value, it is determined that SOFA air door amount of bias；SOFA air door amount of bias is superposed with the current SOFA throttle opening instruction obtained from low nitrogen burning Controlling model, to obtain calibrated SOFA throttle opening instruction, calibrated SOFA throttle opening instruction is sent to DCS402.
Wherein, the low nitrogen burning Controlling model pre-set can pass through Thermal-state test fine in a large number and obtain.Such as, discharged nitrous oxides and boiler efficiency can be considered, several atures of coal conventional for power plant and coal pulverizer compound mode, Thermal-state test is carried out under multiple typical loads, obtain NOx target value and secondary wind and SOFA wind optimum air distribution general layout, set up typical condition storehouse with data obtained by experiment for sample point.Thus, PLC from the low nitrogen burning Controlling model pre-set, can obtain the secondary air register opening degree instruction relevant to DCS feedback parameter and SOFA throttle opening instruction.
The low nitrogen burning based on PLC provided based on the above embodiment of the present invention controls system, corresponding secondary air register opening degree instruction and SOFA air door instruction is determined according to the DCS boiler operating parameter fed back by PLC, and according to nitrogen oxides measured value, SOFA air door instruction is modified, thus the low nitrogen burning effectively realizing boiler controls, it is achieved economic and environment-friendly optimization of boiler runs.
Preferably, the available Modbus agreement of PLC401 carries out opposing traffic with DCS402, and DCS402 can control main combustion zone secondary air register and SOFA air door by hardwire.
In one embodiment, PLC401 is additionally operable to store in low nitrogen burning Controlling model the DCS402 boiler operating parameter fed back and corresponding secondary air register opening degree instruction, SOFA throttle opening instruction and SOFA air door amount of bias.
Thus, by as the course data histories sample of typical condition, typical condition storehouse can be added to during using control program actual motion, abundant typical condition storehouse further, and revise further and optimize Combustion System model.
In one embodiment, PLC401 specifically when arriving for the n-th calculating cycle, calculates current NOx target value SPnWith current nitrogen oxides measured value PVnDifference Errorn；Determine ErrornAffiliated interval X and Errorn-1Affiliated interval Y；Determine corresponding control parameter Z according to interval X and Y, wherein control parameter Z and include proportionality coefficient CP, integral coefficient CI, differential coefficient CD；The PID calculating for the n-th calculating cycle exports PIDOUTn, wherein PIDOUTn=MP,n+MI,n+MD,n=CP*Errorn+(MI,n-1+CI*Errorn-1)+CD*(PVn-1-PVn), MP,nIt is the PID ratio output in the n-th calculating cycle, MI,nIt is the integration output in the n-th calculating cycle, MD,nIt it is the differential output in the n-th calculating cycle；By PIDOUTnIt is converted into corresponding SOFA air door amount of bias.
Preferably, PLC401 specifically utilizes formula
Errorn=a* (SPn-PVn)+(1-a)*Errorn-1
Calculate difference Errorn, wherein a is filter factor.
Preferably, PLC401 specifically, after determining corresponding control parameter Z according to interval X and Y, also includes: judge to control whether parameter Z is enable first；If controlling parameter Z to enable first, then perform to calculate the PID in the n-th calculating cycle and export PIDOUTnOperation；If controlling parameter Z for enable first, then to the integration output M in (n-1)th calculating cycleI,n-1Initialize, MI,n-1=PIDOUTn-1-MP,n+MD,n, then perform to calculate the PID in the n-th calculating cycle and export PIDOUTnOperation.
Wherein, when controlling parameter Z for enabling first, by integration output is initialized, it can be ensured that control program is when switching over, and PID output does not have disturbance, in order to ensure the stability of system.
Additionally, in order to improve security of system, communication security relay protective scheme can be increased further.Such as, respectively through monitoring heartbeat signal, DCS402 and PLC401 can judge that whether the communication between DCS402 and PLC401 is normal.
In one embodiment, DCS402 is additionally operable to after receiving the PLC401 instruction sent, it is judged that currently whether self is in low nitrogen burning control model, and wherein DCS402 exits low nitrogen burning control model when judging the appearance exception of the communication with PLC.If currently self being in low nitrogen burning control model, then determine whether the parameter in instruction whether effectively, whether Parameters variation speed in preset range；If the parameter in instruction is effective and Parameters variation speed is in preset range, then utilize instruction that corresponding air door is controlled；If the invalid parameters in instruction, or Parameters variation speed is beyond preset range, the then instruction that refusal execution receives.If the invalid parameters occurred continuously in instruction, or Parameters variation speed is beyond the situation of preset range, then also can exit low nitrogen burning control model.
In another embodiment, PLC401 judges whether to be adopted also dependent on effectiveness and the rate of change of the DCS402 data fed back.
Fig. 5 is the schematic diagram that low nitrogen burning of the present invention controls system one embodiment of configuration.As it is shown in figure 5, PLC and DCS is communicated by Modbus agreement.The boiler operating parameter such as load, primary air pressure and nitrogen oxides measured value are fed back to PLC by DCS at predetermined intervals or in real time.PLC is according to DCS feedack, the low nitrogen burning Controlling model pre-set is utilized to obtain corresponding secondary air register opening degree instruction and SOFA throttle opening instruction, wherein the instruction of SOFA throttle opening can be through what low nitrogen burning Controlling model directly obtained, it is also possible to is through based on the SOFA throttle opening instruction after the determined SOFA air door offset correction of the difference between nitrogen oxides measured value and nitrogen oxides desired value.Secondary air register opening degree instruction and SOFA throttle opening instruction are sent to DCS by PLC, in order to DCS utilizes secondary air register opening degree instruction and SOFA throttle opening instruction that corresponding secondary air register and SOFA air door are controlled.Secondary air register and SOFA air door also can by throttle opening feedback of status to DCS, in order to DCS carries out airdoor control.
Wherein, the control algolithm of PLC can adopt the structured text programming language programming meeting IEC61131-3 standard, and it is similar to computer advanced programming language, it is possible to realize complicated control computing, thus not by the impact of DCS.
Fig. 6 is the schematic diagram that low nitrogen burning of the present invention control system configures another embodiment.Compared with embodiment illustrated in fig. 5, in the embodiment shown in fig. 6, industrial computer be may further be provided.Wherein industrial computer is communicated with PLC by ICP/IP protocol.System-computed result can be supplied to industrial computer by PLC.Can running a set of configuration software on industrial computer to control the man machine interface of system as low nitrogen burning, user can pass through man machine interface completion system parameter configuration, online data is shown and the inquiry of historical data analysis.The systematic parameter of user setup can be sent to PLC by industrial computer, in order to system is controlled.
By implementing the present invention, can according to factors such as load, ature of coal, oxygen amount, air quantity, coal pulverizer compound modes, choose the air distribution scheme under corresponding fired state, and the air distribution scheme of SOFA wind can be revised in real time according to nitrogen oxides value of feedback, thus the low nitrogen burning effectively realizing boiler controls, the economic and environment-friendly optimization simultaneously realizing boiler runs.
One of ordinary skill in the art will appreciate that all or part of step realizing above-described embodiment can be completed by hardware, can also be completed by the hardware that program carrys out instruction relevant, described program can be stored in a kind of computer-readable recording medium, storage medium mentioned above can be read only memory, disk or CD etc..
Description of the invention provides for example with for the purpose of describing, and is not exhaustively or limit the invention to disclosed form.Many modifications and variations are obvious for the ordinary skill in the art.Selecting and describing embodiment is in order to principles of the invention and practical application are better described, and makes those of ordinary skill in the art it will be appreciated that the present invention is thus design is suitable to the various embodiments with various amendments of special-purpose.
Claims (12)
1. the low nitrogen burning control method based on PLC, it is characterised in that including:
Programmable controller PLC is according to the dcs DCS boiler operating parameter fed back, the low nitrogen burning Controlling model pre-set obtains corresponding secondary air register opening degree instruction and separate type burnout degree SOFA throttle opening instruction and corresponding NOx target value；
Secondary air register opening degree instruction and SOFA throttle opening instruction are sent to DCS by PLC, in order to DCS utilizes secondary air register opening degree instruction and SOFA throttle opening instruction respectively secondary air register and SOFA air door to be controlled；
PLC is according to the DCS nitrogen oxides measured value fed back and current NOx target value, it is determined that SOFA air door amount of bias；
SOFA air door amount of bias is superposed by PLC with the current SOFA throttle opening instruction obtained from low nitrogen burning Controlling model, to obtain calibrated SOFA throttle opening instruction；
Calibrated SOFA throttle opening instruction is sent to DCS by PLC, in order to DCS utilizes calibrated SOFA throttle opening instruction that SOFA air door is controlled；
Wherein, DCS is after receiving the PLC instruction sent, it is judged that currently whether self is in low nitrogen burning control model；
If currently self being in low nitrogen burning control model, then DCS determine whether the parameter in instruction whether effectively, whether Parameters variation speed in preset range；
If the parameter in instruction is effective and Parameters variation speed is in preset range, then DCS utilizes instruction that corresponding air door is controlled.
2. method according to claim 1, it is characterised in that
PLC is by the DCS boiler operating parameter fed back and nitrogen oxides measured value, and corresponding secondary air register opening degree instruction, SOFA throttle opening instruction and SOFA air door amount of bias store in low nitrogen burning Controlling model, in order to revises and optimizes Combustion System model.
3. method according to claim 1, it is characterised in that
PLC is according to the DCS nitrogen oxides measured value fed back and current NOx target value, it is determined that the step of SOFA air door amount of bias includes:
PLC, when arriving for the n-th calculating cycle, calculates current NOx target value SPnWith current nitrogen oxides measured value PVnDifference Errorn；
Determine ErrornAffiliated interval X and Errorn-1Affiliated interval Y；
Determine corresponding control parameter Z according to interval X and Y, wherein control parameter Z and include proportionality coefficient CP, integral coefficient CI, differential coefficient CD；
The PID calculating for the n-th calculating cycle exports PIDOUTn, wherein PIDOUTn=MP,n+MI,n+MD,n=CP*Errorn+(MI,n-1+CI*Errorn-1)+CD*(PVn-1-PVn), MP,nIt is the PID ratio output in the n-th calculating cycle, MI,nIt is the integration output in the n-th calculating cycle, MD,nIt it is the differential output in the n-th calculating cycle；
By PIDOUTnIt is converted into corresponding SOFA air door amount of bias.
4. method according to claim 3, it is characterised in that
Determine the step of corresponding control parameter Z according to interval X and Y after, also include:
Judge to control whether parameter Z is enable first；
If controlling parameter Z to enable first, then perform to calculate the PID in the n-th calculating cycle and export PIDOUTnStep；
If controlling parameter Z for enable first, then to the integration output M in (n-1)th calculating cycleI,n-1Initialize, MI,n-1=PIDOUTn-1-MP,n+MD,n, then perform to calculate the PID in the n-th calculating cycle and export PIDOUTnStep.
5. method according to claim 3, it is characterised in that
Errorn=a* (SPn-PVn)+(1-a)*Errorn-1；
Wherein a is filter factor.
6. the method according to any one of claim 1-5, it is characterised in that
DCS exits low nitrogen burning control model when judging the appearance exception of the communication with PLC；
If the invalid parameters in instruction, or Parameters variation speed is beyond preset range, the then instruction that the execution of DCS refusal receives.
7. the low nitrogen burning based on PLC controls system, it is characterised in that include programmable controller PLC and dcs DCS, wherein:
DCS, for feeding back boiler operating parameter and nitrogen oxides measured value to PLC, when receiving the PLC secondary air register opening degree instruction sent and separate type burnout degree SOFA throttle opening instruction, secondary air register opening degree instruction and SOFA throttle opening instruction is utilized respectively secondary air register and SOFA air door to be controlled；When receiving the PLC calibrated SOFA throttle opening instruction sent, utilize calibrated SOFA throttle opening instruction that SOFA air door is controlled；Wherein after receiving the PLC instruction sent, judge currently self whether be in low nitrogen burning control model, if currently self being in low nitrogen burning control model, then determine whether the parameter in instruction whether effectively, whether Parameters variation speed in preset range, if the parameter in instruction is effective and Parameters variation speed is in preset range, then utilize instruction that corresponding air door is controlled；
PLC, for the boiler operating parameter according to DCS feedback, obtains corresponding secondary air register opening degree instruction and SOFA throttle opening instruction and corresponding NOx target value in the low nitrogen burning Controlling model pre-set；Secondary air register opening degree instruction and SOFA throttle opening instruction are sent to DCS；According to the DCS nitrogen oxides measured value fed back and current NOx target value, it is determined that SOFA air door amount of bias；SOFA air door amount of bias is superposed with the current SOFA throttle opening instruction obtained from low nitrogen burning Controlling model, to obtain calibrated SOFA throttle opening instruction, calibrated SOFA throttle opening instruction is sent to DCS.
8. system according to claim 7, it is characterised in that
PLC is additionally operable to the DCS boiler operating parameter fed back and nitrogen oxides measured value, and corresponding secondary air register opening degree instruction, SOFA throttle opening instruction and SOFA air door amount of bias store in low nitrogen burning Controlling model, in order to revises and optimizes Combustion System model.
9. system according to claim 7, it is characterised in that
PLC specifically when arriving for the n-th calculating cycle, calculates current NOx target value SPnWith current nitrogen oxides measured value PVnDifference Errorn；Determine ErrornAffiliated interval X and Errorn-1Affiliated interval Y；Determine corresponding control parameter Z according to interval X and Y, wherein control parameter Z and include proportionality coefficient CP, integral coefficient CI, differential coefficient CD；The PID calculating for the n-th calculating cycle exports PIDOUTn, wherein PIDOUTn=MP,n+MI,n+MD,n=CP*Errorn+(MI,n-1+CI*Errorn-1)+CD*(PVn-1-PVn), MP,nIt is the PID ratio output in the n-th calculating cycle, MI,nIt is the integration output in the n-th calculating cycle, MD,nIt it is the differential output in the n-th calculating cycle；By PIDOUTnIt is converted into corresponding SOFA air door amount of bias.
10. system according to claim 9, it is characterised in that
PLC specifically, after determining corresponding control parameter Z according to interval X and Y, also includes: judge to control whether parameter Z is enable first；If controlling parameter Z to enable first, then perform to calculate the PID in the n-th calculating cycle and export PIDOUTnOperation；If controlling parameter Z for enable first, then to the integration output M in (n-1)th calculating cycleI,n-1Initialize, MI,n-1=PIDOUTn-1-MP,n+MD,n, then perform to calculate the PID in the n-th calculating cycle and export PIDOUTnOperation.
11. system according to claim 9, it is characterised in that
PLC specifically utilizes formula
Errorn=a* (SPn-PVn)+(1-a)*Errorn-1
Calculate difference Errorn, wherein a is filter factor.
12. system according to claim 7, it is characterised in that
DCS is additionally operable to when judging the appearance exception of the communication with PLC and exits low nitrogen burning control model；It is additionally operable to the invalid parameters in instruction, or when Parameters variation speed exceeds preset range, refusal performs the instruction received.
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| CN109114586A (en) * | 2018-01-25 | 2019-01-01 | 内蒙古大唐国际托克托发电有限责任公司 | A kind of secondary air register control system and method |
| CN108592080B (en) * | 2018-03-01 | 2019-10-15 | 中国神华能源股份有限公司 | Boiler combustion control system and method |
| CN109058969B (en) * | 2018-06-28 | 2019-09-17 | 国电南京电力试验研究有限公司 | A kind of ultra supercritical double reheat tower boiler progress control method |
| CN111637490A (en) * | 2020-05-11 | 2020-09-08 | 中国神华能源股份有限公司国华电力分公司 | Secondary air door control method and system for four-corner tangential boiler |
| CN113266843B (en) * | 2021-04-08 | 2022-08-30 | 华中科技大学 | Combustion optimization method, system and device for coal-fired boiler |
| CN113701187B (en) * | 2021-08-04 | 2023-02-17 | 苏州西热节能环保技术有限公司 | Method for controlling opening degree of burnout air door and storage medium thereof |
| CN113864812A (en) * | 2021-10-08 | 2021-12-31 | 大唐陕西发电有限公司 | Intelligent optimization method and control system for boiler secondary air door |
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