CN111142377A - Fuel quantity feedforward control method of coordinated control system considering operation state of coal mill - Google Patents
Fuel quantity feedforward control method of coordinated control system considering operation state of coal mill Download PDFInfo
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Abstract
The invention discloses a fuel quantity feedforward control method of a coordinated control system considering the running state of a coal mill, which comprises the following steps: respectively selecting a representative value of the ratio of the current of each coal mill to the coal feeding amount of the coal mill, a representative value of the ratio of the primary air pressure to the coal feeding amount of each coal mill and a representative value of the coal feeding amount of each coal mill for all the automatic coal mills to be put into; and respectively calculating inertia time of the AGC commands corresponding to the representative values to the actual differential control action in the fuel quantity feedforward link, and selecting the maximum value of the inertia time as the final inertia time of the actual differential link after first-order inertia filtering. The method is particularly suitable for the thermal power generating unit with complex coal quality and frequent fluctuation of AGC commands, the control system can coordinate the contradiction between the steam pressure control quality before the steam turbine and the operation safety of the pulverizing system in the variable load process, the limit performance of the equipment is exerted to the maximum extent, and the best control effect is obtained on the premise that the pulverizing system does not break down.
Description
Technical Field
The invention relates to the technical field of fuel quantity control of a thermal generator set coordinated control system, in particular to a fuel quantity feedforward control method of the coordinated control system considering the running state of a coal mill.
Background
The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art.
The power grid requires that the actual power generation load of the thermal power generating unit quickly follows the instruction change of the power grid AGC (automatic power generation control), so that under the normal working condition, the thermal power generating unit coordinated control system needs to put into a coordinated control mode based on the boiler and the generator, namely, the power generation load is controlled through the opening of a regulating valve of the steam turbine, and the steam pressure before the steam turbine is controlled through the fuel quantity of the boiler. The controlled object of the coordination control system is characterized in that: the process of the steam pressure before the steam turbine and the power generation load responding to the opening change of the steam turbine regulating valve is very quick, and the process of responding to the change of the fuel quantity of the boiler is very slow. Therefore, it is relatively easy to control any one of the parameters using a turbine governor valve, and it is difficult to control any one of the parameters using fuel quantity. Therefore, the control mode of the boiler-following machine is characterized by good control quality of the power generation load and poor control quality of the steam pressure in front of the steam turbine. In order to reduce the fluctuation of the pressure before the machine in the variable load process and improve the control quality of the pressure before the machine as much as possible, the machine and furnace coordination control mode is designed with a feedforward control logic of AGC commands to fuel quantity to form a feedforward and feedback composite control system.
Large inertia and delay of boiler pulverizing systemThe transfer function G of a typical pulverizing system is a main reason for very slow change of front steam pressure of a steam turbine and power generation load response fuel quantityf(s) is:
wherein: k1The static gain of the unit fuel quantity to the power generation load is MW/(t/h); t isfThe inertia time of a boiler pulverizing system is s; tau is the delay time of the boiler pulverizing system, s; s is a complex variable of pull-type transformation and has no unit.
The transfer function of AGC command to fuel quantity feedforward control in a coordinated control system is constructed, and various links generating hysteresis in the transfer function of a pulverizing system need to be eliminated, so that the fuel quantity action is accelerated as much as possible. Because the method for eliminating the pure delay link can not be realized physically, only the inertia link can be eliminated, the transfer function G of the feed-forward control of the AGC instruction to the fuel quantity is obtainedpr(s) is of the form:
wherein: t isgTo ensure the inertia time, s, of the actual differential element that the transfer function can physically realize.
Inertia time T of medium-speed milling systemfVery large, and T is used to ensure the control effectgShould be significantly less than Tf. The fuel quantity feed forward control therefore exhibits a characteristic of significant differential regulation, which can significantly amplify the variation of the AGC command. For example, the static gain of a certain unit fuel quantity to the power generation load is 2MW/(t/h), which means that under a static condition, the AGC command changes by 20MW, and the fuel quantity only needs to change by 10 t/h. However, due to the amplification effect of the fuel quantity feed-forward control, when the AGC command changes by 20MW, the fuel quantity instantaneous change amplitude can reach 30t/h and then gradually returns to 10t/h, and the faster the unit responds to the AGC command change rate, the larger the fuel quantity instantaneous change amplitude is. Therefore, the fuel quantity feedforward control can improve the control quality by increasing the fluctuation range of the fuel quantityAt the expense of.
The fuel quantity is greatly fluctuated due to frequent AGC command change, severe combustion disturbance can be caused, and further, the hearth pressure, the oxygen content of flue gas, the temperature of overheating/reheating steam and NO are causedXThe parameters such as the generation amount and the like are unstable, and the running safety, the economical efficiency and the cleanness of the unit are reduced. Particularly, as the coal price rises and the coal quality of coal fired in a power plant becomes poor, the operation safety of a coal pulverizing system can be seriously reduced due to the large fluctuation of the fuel quantity.
Most of thermal power generating units adopt a medium-speed mill positive-pressure direct-fired pulverizing system. The coal mills are key equipment in the coal pulverizing system, the fuel quantity instruction in the fuel quantity control system is converted into a coal feeding quantity instruction of each coal mill, and the quantity of coal entering the coal mills is changed along with the coal feeding quantity instruction. Raw coal is rolled and ground between a grinding disc and a grinding roller at the bottom of the coal mill, then blown by primary air to pass through a coarse powder separator, qualified coal powder is conveyed to a boiler burner by the primary air, and unqualified coal particles return to the bottom of the mill to be continuously ground. The medium-speed mill is very sensitive to impurities such as sand, pebbles, wood blocks and the like in raw coal, in the grinding process of the raw coal, the impurities can press against a large gap formed between a grinding disc and a grinding roller, so that the raw coal in the raw coal cannot be effectively ground and grinded, a large amount of impurities and coal particles are repeatedly circulated in the mill, the amount of coal stored in the mill is increased, the grinding current is increased, the pulverizing output is reduced, slight blockage is formed, and if a control system continuously and greatly increases the coal feeding amount, the situation is rapidly aggravated, and the coal mill is seriously blocked. Generally, when the blockage is slight, the fault can be eliminated by adopting the measures of temporarily reducing coal feeding and increasing primary air volume for purging, and when the blockage is serious, only the grinding is stopped and the coal is cleaned by entering a coal grinding machine by maintainers. On the contrary, when the amount of coal stored in the coal mill is too small, the coal feeding amount is greatly reduced, so that the coal on the grinding disc is not uniformly spread, the grinding disc directly collides with the grinding roller when rotating, so that the coal mill vibrates violently, and the faults of large shaft of the grinding roller and fracture of the reduction gear of the grinding disc can be caused in serious cases.
The fuel quantity feedforward control in the traditional coordinated control system does not take into account the changes of the running states of a coal mill and a powder preparation system, the fuel quantity is always increased or decreased according to a fixed feedforward amplitude when the load is changed, and when the running state of the powder preparation system is not good, a good control effect cannot be obtained, but the running state of the powder preparation system is further deteriorated.
Disclosure of Invention
Aiming at the defects that the operation state of a coal pulverizing system is not considered in the feed-forward control of fuel quantity by an AGC instruction in the existing coordinated control system, and the blockage or no-load vibration of a coal pulverizer is easily caused in the variable load process, the invention provides the fuel quantity feed-forward control method of the coordinated control system taking the operation state of the coal pulverizer into consideration, which can better coordinate the contradiction between the steam pressure control quality before a steam turbine and the operation safety of the coal pulverizing system in the variable load process, optimize and adjust the variation range of a feed-forward signal on the premise of keeping the feed-forward total quantity unchanged, finally realize the purposes of greatly increasing and decreasing the fuel quantity quickly and preferentially ensuring the steam pressure control quality before the steam turbine when the operation state of the coal pulverizing system is good, and preferentially ensure the stable operation of the coal.
In some embodiments, the following technical scheme is adopted:
the fuel quantity feedforward control method of the coordinated control system considering the running state of the coal mill comprises the following steps:
respectively selecting a representative value of the ratio of the current of each coal mill to the coal feeding amount of the coal mill, a representative value of the ratio of the primary air pressure to the coal feeding amount of each coal mill and a representative value of the coal feeding amount of each coal mill for all the automatic coal mills to be put into;
and respectively calculating inertia time of the AGC commands corresponding to the representative values to the actual differential control action in the fuel quantity feedforward link, and selecting the maximum value of the inertia time as the final inertia time of the actual differential link after first-order inertia filtering.
After obtaining the inertia time of the actual differential link, the method also comprises the following processes:
the inertia time of the powder making system is divided by the inertia time of an actual differential link and then 1 is subtracted to obtain an intermediate coefficient;
dividing the actual AGC command signal of the unit by the value of the static gain of the fuel quantity to the generated power to obtain a static fuel quantity feedforward signal;
and subtracting the static fuel quantity feedforward signal from the static fuel quantity feedforward signal, setting the inertia time of the static fuel quantity feedforward signal as a signal output by a first-order inertia module of the inertia time of an actual differential link, and multiplying the signal by the intermediate coefficient to obtain a value and adding the static fuel quantity feedforward signal to obtain a feedforward signal of the AGC instruction to the fuel quantity.
Compared with the prior art, the invention has the beneficial effects that:
(1) the fuel quantity feedforward control method of the coordinated control system considering the running state of the coal mill is particularly suitable for thermal power generating units with complex coal quality and frequent fluctuation of AGC (automatic gain control) instructions, the control system can coordinate contradictions between the front steam pressure control quality of a steam turbine and the running safety of a pulverizing system in the process of load change, the limit performance of equipment is exerted to the maximum extent, and the best control effect is obtained on the premise that the pulverizing system does not break down.
(2) The control logic can be put into use only after configuration and parameter setting are completed according to the implementation scheme, and field debugging is not needed, so that the implementation is convenient.
Drawings
FIG. 1 is a response curve of an actual differential element to a step input according to an embodiment of the present invention;
FIG. 2 is a logic for calculating a representative value of a ratio of a current of a coal mill to a coal feeding amount of the coal mill according to an embodiment of the present invention;
FIG. 3 is a logic of calculating a representative value of a ratio of primary air pressure to coal feed rate of a coal mill according to an embodiment of the present invention;
FIG. 4 is a logic for calculating a representative value of coal feed rate of a coal pulverizer according to a first embodiment of the present invention;
FIG. 5 is a logic diagram of the feedforward control of the AGC command to the fuel amount according to one embodiment of the present invention.
Detailed Description
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, components, and/or combinations thereof, unless the context clearly indicates otherwise.
Example one
In one or more embodiments, a method for feedforward control of fuel quantity in a coordinated control system taking into account the operating state of a coal mill is disclosed, implemented in a DCS (distributed control system) in a logical configuration, comprising the following processes:
respectively selecting a representative value of the ratio of the current of each coal mill to the coal feeding amount of the coal mill, a representative value of the ratio of the primary air pressure to the coal feeding amount of each coal mill and a representative value of the coal feeding amount of each coal mill for all the automatic coal mills to be put into;
and respectively calculating inertia time of the AGC commands corresponding to the representative values to the actual differential control action in the fuel quantity feedforward link, and selecting the maximum value of the inertia time as the final inertia time of the actual differential link after first-order inertia filtering.
The method is characterized in that according to the change conditions of three signals, namely the ratio of the current of each coal mill to the coal feeding amount of the coal mill, the ratio of primary air pressure to the coal feeding amount of each coal mill and the coal feeding amount of each coal mill in the unit operation process, the inertia time of the actual differential control action of an AGC instruction in a fuel amount feedforward link is adjusted on line, the change amplitude of a feedforward signal is optimized and adjusted on the premise of keeping the total feedforward quantity unchanged, and finally the purposes that when a powder preparation system is in a good operation state, the fuel amount is increased and decreased rapidly to a large extent, the steam pressure control quality before a steam turbine is preferentially ensured, and when the powder preparation system is in a bad operation state, the fuel amount is. The control method has the advantages of definite physical significance and simple and convenient field implementation.
The method of this embodiment is described in detail below:
(1) analysis of actual differential ring characteristics
The ideal differential link is physically impossible to realize, and the actual differential link transfer function Gd(s) has the structure:
wherein: t isdIs the differential time, s.
Differential time TdDetermines the magnitude of the total differential quantity, and the inertia time T of the actual differential elementgThe amplitude and the time of change of the differential response are affected. FIG. 1 shows the inertia time T of the actual differential elementgThe response curve of the actual differential link to the step input is different. T isgThe larger the magnitude of the change in the amplitude of the response curve, the longer the duration of the response curve, but the total area of the response curve remains the same. Theoretically, the maximum variation amplitude of the output of the differential link can be changed by adjusting the inertia time of the actual differential link under the condition that the total differential amount is kept unchanged.
The formula (2) is deformed and then is shown as the formula (4). It can be found that the transfer function G of the feedforward control of the AGC command to the fuel quantityprAnd(s) is actually formed by adding a static gain term and an actual differential element, so that the action amplitude of the feedforward control can be adjusted by adjusting the inertia time of the actual differential element.
Further deforming the formula (4), the structure which is shown in the formula (5) and is convenient for realizing engineering configuration can be obtained. The method is mainly realized by equivalently transforming an actual differential link into an inertial link.
(2) Signal for reflecting running state of pulverizing system
The ratio of the mill current to the mill coal feed can represent the grindability of the coal. Under the condition that the coal feeding amount is the same, the larger the current of the coal mill is, the poorer the coal grindability is, the more coal is stored in the corresponding coal mill, and the higher the risk of blockage of the coal mill is. On the contrary, under the condition that the coal feeding amount is the same, the smaller the current of the coal mill is, the better the coal grindability is, the less the coal is stored in the corresponding coal mill, and the higher the risk of no-load vibration of the coal mill is. In addition, the coal mill has the requirements of the highest primary air pressure and the lowest primary air pressure during design, the higher the ratio of the primary air pressure to the coal feeding quantity is, the stronger the carrying capacity of the primary air is, and the more easily the coal mill generates no-load vibration; the lower the ratio of the primary air pressure to the coal feeding amount is, the weaker the carrying capacity of the primary air is, and the more easily the coal mill is blocked. Furthermore, coal mills are designed with limits on maximum and minimum coal feed. When the coal feeding amount approaches or exceeds the maximum designed coal feeding amount, the coal mill is easy to block; when the coal feeding amount is close to or lower than the minimum designed coal feeding amount, the coal mill is easy to vibrate in a no-load mode. Therefore, when any one of three signals, namely the ratio of the current of the coal mill to the coal feeding quantity of the coal mill, the ratio of the primary air pressure to the coal feeding quantity of the coal mill and the coal feeding quantity of the coal mill, is obviously beyond a normal range, the variation range of the fuel quantity instruction needs to be properly reduced, and the coal mill is prevented from being abnormal.
(3) Signal synthesis processing
The following describes how to determine the actual differential link inertia time according to three signals, namely the ratio of the current of the coal mill to the coal feeding amount of the coal mill, the ratio of the primary air pressure to the coal feeding amount of the coal mill, and the coal feeding amount of the coal mill.
A plurality of coal mills are arranged in the thermal power generating unit and operate in parallel. And starting coal mills with different numbers according to the total fuel quantity instruction of the unit on site, so that the coal feeding amount of each coal mill is in a reasonable range. When the coal mill works normally, an operator can put the coal feeding amount control of the coal feeder corresponding to the coal mill into automatic control to participate in automatic adjustment of the total fuel amount. Therefore, three signals of the ratio of the current of the coal mill to the coal feeding quantity of the coal mill, the ratio of the primary air pressure to the coal feeding quantity of the coal mill and the coal feeding quantity of the coal mill can be generated when each coal feeding quantity is input into the automatic coal mill.
In theory, one of all the coal mills, which should be the most extreme of the three signals, is most prone to blockage or idle vibration, but due to various interference and uncertainty factors in the field, the three signals reflect that the blockage or idle vibration of the coal mill is not very accurate, and there is a possibility of missing or erroneous judgment.
Therefore, the principle of similar voting is adopted to carry out signal comprehensive processing, and the method comprises the following steps: and (3) putting all coal feeding quantities into an automatic coal mill, selecting a second maximum value in the ratio of the current of the coal mill to the coal feeding quantity of the coal mill as a representative value of the ratio of the current of the coal mill to the coal feeding quantity of the coal mill, respectively selecting a second maximum value in the ratio of the primary air pressure to the coal feeding quantity of the coal mill and a second maximum value in the coal feeding quantity of the coal mill as the representative value of the ratio of the coal feeding quantity of the coal mill to the primary air pressure to the coal mill, respectively calculating inertia time of respective corresponding actual differential links according to the three representative values, and then selecting a maximum value as the inertia time of a final actual differential link.
The technical scheme of the invention is illustrated by taking a thermal power generating unit provided with 5 coal mills as an example. The schematic structural diagrams of the control system for implementing the control method of the invention are shown in fig. 2-5. Wherein, fig. 2 is a logic for calculating a representative value of a ratio of current of the coal mill to coal feeding amount of the coal mill, fig. 3 is a logic for calculating a representative value of a ratio of primary air pressure to coal feeding amount of the coal mill, fig. 4 is a logic for calculating a representative value of coal feeding amount of the coal mill, and fig. 5 is a logic for feedforward control of AGC command to fuel amount.
In FIGS. 2 to 5: DIV 1-DIV 12 are division calculation modules 1-12, and the input end with the mark "B" is dividend; T1-T15 are signal selection modules, when the signal of the right switching value input end is '1', the signal of the 'Y' input end is selected as output, and when the signal of the switching value input end is '0', the signal of the 'N' input end is selected as output; LS 1-LS 30 are small selection modules 1-30, and have the functions of comparing the numerical values of two input signals and selecting the signal with a small numerical value as output; HS 1-HS 29 are large selection modules 1-29, and have the functions of comparing the numerical values of two input signals and selecting the signal with the large numerical value as output; f (x) 1-F (x)3 are multi-point polyline function modules 1-c3; LAG 1-2 are first-order inertia modules 1-2, wherein the input end of a right arrow in LAG2 is an inertia time value input end; SUM 1-SUM 3 are summation calculation modules 1-3; MUL is a multiplication module; k1、Tf1 are constant modules which respectively output a constant K1、Tf、1。
In fig. 2, the ratio of the current of the coal mill to the coal feeding amount of 5 coal mills of A, B, C, D, E is calculated respectively; then judging whether the coal feeding amount of the coal mill is automatically controlled, outputting a calculated ratio if the coal feeding amount is automatically controlled, and outputting 0 if the coal feeding amount is not automatically controlled; and finally, selecting a second largest value from the 5 signals as a representative value of the ratio of the current of the coal mill to the coal feeding amount of the coal mill. The logic in which the next largest value is selected is: two groups of 5 input signals are respectively selected to be small, and then the maximum value is selected from all the small output values.
In fig. 3, the ratio of the primary air pressure to the coal feeding amount of 5 coal mills of A, B, C, D, E is calculated respectively; then judging whether the coal feeding amount of the coal mill is put into automation or not, outputting a calculated ratio if the coal feeding amount of the coal mill is put into automation, and outputting 0 if the coal feeding amount of the coal mill is not put into automation; and finally, selecting a second largest value from the 5 signals as a representative value of the ratio of the primary air pressure to the coal feeding quantity of the coal mill. The logic in which the next largest value is selected is: two groups of 5 input signals are respectively selected to be small, and then the maximum value is selected from all the small output values.
In fig. 4, it is determined whether coal feeding amount of 5 coal mills of A, B, C, D, E is put into automation, the calculated coal feeding amount of the coal mill is output when the coal feeding amount is put into automation, and 0 is output when the coal feeding amount is not put into automation; and finally, selecting the second largest value from the 5 signals as a representative value of the coal feeding amount of the coal mill. The logic in which the next largest value is selected is: two groups of 5 input signals are respectively selected to be small, and then the maximum value is selected from all the small output values.
In fig. 5, the representative value of the ratio of the current of the coal mill to the coal feeding amount of the coal mill, the representative value of the ratio of the primary wind pressure to the coal feeding amount of the coal mill, and the representative value of the coal feeding amount of the coal mill are respectively subjected to multipoint broken line functions f (x)1 to f (x)3 to calculate the inertia time of the corresponding actual differential link, and then the maximum value of the calculated inertia time is selected through HS28 and HS29 and subjected to first-order inertia filtering through LAG1Obtaining the final actual differential link inertia time T after the wavegThe numerical value of (c).
Inertia time T of pulverizing systemfIs divided by the actual differential element inertia time T by the value of DIV12gSubtracting 1 from SUM1 to obtain an intermediate coefficient; the actual AGC command signal of the unit is divided by the value K of the static gain of the fuel quantity to the generated power through the DIV111Then obtaining a static fuel quantity feedforward signal, and setting the inertia time of the static fuel quantity feedforward signal subtracted by the SUM2 as the inertia time T of a differential linkgThe output signal of the first-order inertia module LAG2 is multiplied by an intermediate coefficient through MUL, and finally, a static fuel quantity feedforward signal is added through SUM3 to obtain a feedforward signal of an AGC command to the fuel quantity.
The logic of fig. 2-5 of the control system architecture implementing the control method of the present invention. Inertial time of LAG1 module is set to 10s, K1、TfAnd the output value of the constant module is respectively set as the static gain of the unit fuel quantity in the original coordinated control system to the power generation power and the inertia time of the boiler pulverizing system. The setting methods of the multi-point polyline function modules F (x) 1-F (x)3 are shown in tables 1-3.
TABLE 1 setup of the Multi-Point polyline function Module F (x)1
| |
1 | 2 | 3 | 4 | 5 |
| Input device | 0.0×Ibe | 0.5×Ibe | 0.8×Ibe | 1.2×Ibe | 2.0×Ibe |
| Output of | 50 | 40 | 20 | 40 | 80 |
Wherein: i isbeThe ratio of the rated working current to the rated coal feeding amount of the coal mill is A/(t/h).
TABLE 2 setup of the Multi-Point polyline function Module F (x)2
| |
1 | 2 | 3 | 4 | 5 |
| Input device | 0.0×Pbe | 0.7×Pbe | 0.9×Pbe | 1.1×Pbe | 1.5×Pbe |
| Output of | 80 | 60 | 20 | 20 | 50 |
Wherein: pbeThe ratio of the rated primary air pressure to the rated coal feeding quantity of the coal mill is kPa/(t/h).
TABLE 3 setup of the Multi-point polyline function Module F (x)3
| |
1 | 2 | 3 | 4 | 5 |
| Input device | 0.0×Rme | 0.5×Rme | 0.7×Rme | 1.0×Rme | 1.2×Rme |
| Output of | 50 | 30 | 20 | 30 | 80 |
Wherein: rmeThe rated coal feeding amount of the coal mill is t/h.
Example two
In one or more embodiments, disclosed is a fuel quantity feedforward control method of a coordinated control system considering the running state of a coal mill, which is implemented in a PLC (programmable logic controller) in a code writing mode, wherein the code implementation function specifically comprises the following steps:
respectively selecting a representative value of the ratio of the current of each coal mill to the coal feeding amount of the coal mill, a representative value of the ratio of the primary air pressure to the coal feeding amount of each coal mill and a representative value of the coal feeding amount of each coal mill for all the automatic coal mills to be put into;
respectively calculating inertia time of the AGC commands corresponding to the representative values to the actual differential control action in the fuel quantity feedforward link, and selecting the maximum value as the final inertia time of the actual differential link;
after obtaining the inertia time of the actual differential link, the method also comprises the following processes:
the inertia time of the powder making system is divided by the inertia time of an actual differential link and then 1 is subtracted to obtain an intermediate coefficient;
dividing the actual AGC command signal of the unit by the value of the static gain of the fuel quantity to the generated power to obtain a static fuel quantity feedforward signal;
and subtracting the signal output by a first-order inertia module, in which the inertia time of the static fuel quantity feedforward signal is set as the inertia time of a differential link, from the static fuel quantity feedforward signal, and multiplying the signal by the intermediate coefficient to obtain a value and adding the static fuel quantity feedforward signal to obtain the feedforward signal of the AGC instruction to the fuel quantity.
The specific implementation process of the above process is the same as that in the first embodiment, and is not described here again.
Although the embodiments of the present invention have been described with reference to the accompanying drawings, it is not intended to limit the scope of the present invention, and it should be understood by those skilled in the art that various modifications and variations can be made without inventive efforts by those skilled in the art based on the technical solution of the present invention.
Claims (9)
1. The fuel quantity feedforward control method of the coordinated control system considering the running state of the coal mill is characterized by comprising the following steps of:
respectively selecting a representative value of the ratio of the current of each coal mill to the coal feeding amount of the coal mill, a representative value of the ratio of the primary air pressure to the coal feeding amount of each coal mill and a representative value of the coal feeding amount of each coal mill for all the automatic coal mills to be put into;
and respectively calculating inertia time of the AGC commands corresponding to the representative values acting on actual differential control in a fuel quantity feedforward link, and selecting the maximum value as the inertia time of the final actual differential link.
2. The fuel quantity feedforward control method of the coordinated control system considering the operation state of the coal pulverizer as recited in claim 1, wherein the representative value of the ratio of the current of each coal pulverizer to the coal feeding quantity of the coal pulverizer is selected as follows:
and selecting the second largest value of the ratio of the current of each coal mill to the coal feeding amount of the coal mill as a representative value.
3. The fuel quantity feedforward control method of the coordinated control system considering the operation state of the coal pulverizer as recited in claim 1, wherein the representative value of the ratio of the primary air pressure to the coal feeding quantity of each coal pulverizer is selected as follows:
and selecting the second largest value of the ratio of the primary air pressure to the coal feeding amount of each coal mill as a representative value.
4. The fuel quantity feedforward control method of the coordinated control system considering the operation state of the coal pulverizer as claimed in claim 1, wherein the representative value of the coal feeding quantity of each coal pulverizer is selected as follows:
and selecting the second largest value of the coal feeding amount of each coal mill as a representative value.
5. The fuel quantity feedforward control method of the coordinated control system considering the operation state of the coal pulverizer as recited in claim 1, wherein a representative value of a ratio of a current of the coal pulverizer to a coal feeding quantity of the coal pulverizer is calculated through a multi-point broken line function, and an inertia time of an AGC command corresponding to the representative value acting on an actual differential control in a fuel quantity feedforward link is calculated.
6. The fuel quantity feedforward control method of the coordinated control system considering the operation state of the coal pulverizer as recited in claim 1, wherein a representative value of a ratio of primary air pressure to a coal feeding quantity of each coal pulverizer is calculated through a multi-point broken line function, and an inertia time of an AGC command corresponding to the representative value acting on actual differential control in a fuel quantity feedforward link is calculated.
7. The fuel quantity feedforward control method of the coordinated control system considering the operation state of the coal mill as claimed in claim 1, wherein the representative value of the coal feeding amount of the coal mill is calculated by a multi-point broken line function, and the inertia time of the actual differential control action of the AGC command corresponding to the representative value on the fuel amount feedforward link is calculated.
8. The feed-forward control method for fuel quantity of a coordinated control system considering the running state of a coal mill as claimed in claim 1, wherein the inertia time of the actual differential control action is calculated by:
and selecting the maximum value from the inertia time of the AGC instruction corresponding to the representative value of the ratio of the current of the coal mill to the coal feeding amount of the coal mill to the actual differential control action in the fuel amount feedforward link, the inertia time of the AGC instruction corresponding to the representative value of the ratio of the primary air pressure to the coal feeding amount of each coal mill to the actual differential control action in the fuel amount feedforward link and the inertia time of the AGC instruction corresponding to the representative value of the coal feeding amount of the coal mill to the actual differential control action in the fuel amount feedforward link, and outputting the maximum value after first-order inertia filtering to serve as the inertia time of the actual differential link.
9. The fuel quantity feedforward control method of the coordinated control system considering the operation state of the coal pulverizer as claimed in claim 1, wherein after obtaining the inertia time of the actual differential link, the method further comprises the following processes:
the inertia time of the powder making system is divided by the inertia time of an actual differential link and then 1 is subtracted to obtain an intermediate coefficient;
dividing the actual AGC command signal of the unit by the value of the static gain of the fuel quantity to the generated power to obtain a static fuel quantity feedforward signal;
and subtracting the signal output by a first-order inertia module, in which the inertia time of the static fuel quantity feedforward signal is set as the inertia time of a differential link, from the static fuel quantity feedforward signal, and multiplying the signal by the intermediate coefficient to obtain a value and adding the static fuel quantity feedforward signal to obtain the feedforward signal of the AGC instruction to the fuel quantity.
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| CN113898968A (en) * | 2021-09-09 | 2022-01-07 | 华电电力科学研究院有限公司 | Balanced coal feeding control method for preventing direct-fired pulverizing system from being blocked and ground |
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