Boiler combustion control system, boiler combustion control method, and program

Abstract

To further improve accuracy in boiler combustion control.SOLUTION: A boiler combustion control system supplies a fuel relating to a fuel charging amount to a boiler calculated on the basis of a fuel function to a load request amount, to the boiler, obtains a feedback (FB) correction amount by PID control on the basis of a measured main steam pressure and a set main steam pressure, and outputs the load request amount after the FB correction or a fuel correction coefficient for correcting the fuel charging amount to a plant in which the load request amount or the fuel charging amount is corrected on the basis of the FB correction amount. The boiler combustion control system includes: a correction portion for obtaining correction amounts of a proportional term and an integration term in the PID control of the FB correction amount on the basis of a boiler input instruction value, the load request amount or the fuel charging amount and the measured main steam pressure, and correcting a reference curve defining a relation between the load request amount and the fuel charging amount in the boiler on the basis of these correction values; and a calculation portion for calculating the fuel correction coefficient on the basis of the corrected reference curve.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a boiler combustion control system, a boiler combustion control method, and a program. [Background technology]

[0002] There is known a boiler combustion control system that determines the amount of fuel input to a boiler based on the load requirement of the boiler. Patent Document 1 describes a boiler combustion control system that detects deviation from an optimal value assumed by a fuel function FX in the behavior of the main steam pressure and makes it possible to autonomously and self-containedly correct the fuel function FX. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2018 / 212224 Summary of the Invention [Problem to be solved by the invention]

[0004] However, even with the boiler combustion control system described in Patent Document 1, there is still room for improving the accuracy of boiler combustion control.

[0005] An object of the present invention is to further improve the accuracy of boiler combustion control.

[0006] The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings. [Means for solving the problem]

[0007] Among the inventions disclosed in this application, a brief summary of representative inventions is as follows.

[0008] A boiler combustion control system according to a representative embodiment of the present invention supplies a boiler with fuel relating to a fuel input amount to the boiler calculated based on a predetermined fuel function for a load demand, calculates a feedback correction amount by PID control based on a measured main steam pressure that is a measured main steam pressure of the boiler and a set main steam pressure that is a preset main steam pressure of the boiler, and outputs a fuel correction coefficient for correcting the load demand or the fuel input amount after the feedback correction to a plant which corrects the load demand or the fuel input amount based on the feedback correction amount. The boiler combustion control system includes: a reference curve correction unit that calculates correction amounts for proportional and integral terms in the PID control of the feedback correction amount based on a boiler input command value, the load demand or the fuel input amount, and the measured main steam pressure, and corrects a reference curve that defines the relationship between the load demand and the fuel input amount for the boiler based on the calculated correction amounts for the proportional and integral terms; and a fuel correction coefficient calculation unit that calculates the fuel correction coefficient based on the corrected reference curve.

[0009] A boiler combustion control method according to a representative embodiment of the present invention is a boiler combustion control method in a boiler combustion control system, which supplies a boiler with fuel relating to a fuel input amount to the boiler calculated based on a predetermined fuel function for a load demand, calculates a feedback correction amount by PID control based on a measured main steam pressure that is a measured main steam pressure of the boiler and a set main steam pressure that is a preset main steam pressure of the boiler, and outputs a fuel correction coefficient for correcting the load demand amount or the fuel input amount after the feedback correction to a plant that corrects the load demand amount or the fuel input amount based on the feedback correction amount, and includes the steps of: calculating correction amounts for proportional and integral terms in the PID control of the feedback correction amount based on a boiler input command value, the load demand amount or the fuel input amount, and the measured main steam pressure; correcting a reference curve that defines the relationship between the load demand amount and the fuel input amount for the boiler based on the calculated correction amounts for the proportional and integral terms; and calculating the fuel correction coefficient based on the corrected reference curve.

[0010] A program according to a representative embodiment of the present invention is a program used in a boiler combustion control system that supplies to a boiler fuel relating to a fuel input amount to the boiler calculated based on a predetermined fuel function for a load demand, calculates a feedback correction amount by PID control based on a measured main steam pressure that is the measured main steam pressure of the boiler and a set main steam pressure that is a preset main steam pressure of the boiler, and outputs a fuel correction coefficient that corrects the load demand amount or the fuel input amount after the feedback correction to a plant that corrects the load demand amount or the fuel input amount based on the feedback correction amount, and causes a processor provided in the boiler combustion control system to execute the steps of: calculating correction amounts for proportional and integral terms in the PID control of the feedback correction amount based on a boiler input command value, the load demand amount or the fuel input amount, and the measured main steam pressure; correcting a reference curve that defines the relationship between the load demand amount and the fuel input amount for the boiler based on the calculated correction amounts for the proportional and integral terms; and calculating the fuel correction coefficient based on the corrected reference curve. Effect of the Invention

[0011] The effects obtained by the representative inventions disclosed in this application will be briefly described as follows.

[0012] That is, according to the representative embodiment of the present invention, it is possible to further improve the accuracy of boiler combustion control. [Brief description of the drawings]

[0013] [Figure 1] 1 is a diagram illustrating an example of a configuration of a boiler combustion control system according to a first embodiment. [Diagram 2] 1 is a diagram showing an example of a configuration implemented by hardware and software of a boiler combustion control system according to a first embodiment. [Diagram 3] FIG. 2 is a diagram showing an overview of an example of the behavior of main steam pressure. [Figure 4] 4 is a diagram illustrating an example of a configuration of a reference curve correction unit in the first embodiment. FIG. [Diagram 5] 5 is a flowchart showing an example of a process flow for correcting a reference curve in the first embodiment. FIG. [Figure 6] FIG. 4 is a diagram showing an example of a flow of a first correction process of a reference curve correction function in the first embodiment. [Figure 7] 4 is a flowchart showing an example of a process flow for determining a PID proportional term correction coefficient K1. FIG. [Figure 8] FIG. 4 is a diagram for explaining a process for determining a PID proportional term correction coefficient K1. [Figure 9] FIG. 4 is a flowchart showing an example of a process flow for determining a PID integral term correction coefficient K2. [Figure 10] FIG. 4 is a diagram for explaining a process for determining a PID integral term correction coefficient K2. [Figure 11] FIG. 11 is a diagram showing an example of a flow of a second correction process of a reference curve correction function in the first embodiment. [Figure 12] FIG. 11 is a diagram illustrating an example of the configuration of a boiler combustion control system according to a second embodiment. [Figure 13] FIG. 11 is a diagram illustrating an example of the configuration of a reference curve correction unit in the second embodiment. [Figure 14] FIG. 11 is a diagram showing an example of a processing flow in a reference curve correction unit in the second embodiment. [Figure 15] FIG. 11 is a diagram showing an example of the flow of a second correction process of a reference curve correction function in the second embodiment. [Figure 16] FIG. 11 is a diagram illustrating an example of a weighting function in the second embodiment. [Figure 17] FIG. 11 is a diagram illustrating an example of a weighting table in the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] <Details of the study by the present inventors> When obtaining energy using a boiler facility, fuel is supplied to the boiler and burned, and the heat is absorbed by a heat exchanger to generate steam and obtain thermal energy. The generated steam is converted from thermal energy to rotational motion by, for example, being supplied to a steam turbine, and is used for generating electricity by a generator. The amount of fuel input to the boiler is determined by a fuel function FX, which is a relational expression between the load demand (for example, the power generation demand MWD (Mega Watt Demand), hereinafter sometimes referred to as the load demand MWD) and the amount of fuel input to the boiler (hereinafter sometimes referred to as the boiler input command value BID (Boiler Input Demand)).

[0015] The boiler is also called a furnace. The fuel is, for example, a solid fuel, a liquid fuel, a gaseous fuel, or a mixture of these fuels.

[0016] Here, the operating state of the boiler, particularly the main steam pressure, may fluctuate due to the influence of various factors related to the boiler equipment, such as fuel properties, heat value, furnace fouling, soot blower, air / water temperature, etc. Therefore, a common control method is to supply fuel related to the fuel input amount calculated by the fuel function FX to the boiler, measure the generated main steam pressure, calculate a feedback correction amount by PID (Proportional-Integral-Differential) control based on the difference between this and a preset main steam pressure, and add this to the load requirement to correct the fuel input amount to the boiler.

[0017] In contrast, in the technology described in Japanese Patent No. 4522326 (first document), Japanese Patent No. 4791269 (second document), etc., in order to further improve the accuracy of control, a fuel correction coefficient is calculated by self-learning based on the ratio of the load demand MWD before and after feedback correction, i.e., an index showing the degree of operation of feedback correction of the main steam pressure, and the load demand MWD or the boiler input command value BID is further corrected by this fuel correction coefficient. This correction is essentially equivalent to correcting the fuel function FX.

[0018] More specifically, the above-mentioned first document describes that a plurality of ratios or differences between values ​​before and after feedback correction are successively updated and stored, a fuel correction coefficient is calculated from the stored plurality of values, and the value after feedback correction is corrected by this correction coefficient. This makes it possible to correct the fuel input amount to an appropriate amount, taking into account changes in the thermal efficiency of the boiler due to the influence of various factors.

[0019] Furthermore, the above-mentioned second document describes that in a multi-fuel mixed combustion boiler, the fuel input amount to the boiler is corrected in response to differences in the unit heat value of the fuels and differences in boiler thermal efficiency that accompany changes in the mixed combustion ratio by subdividing a fuel correction coefficient for correcting the value after feedback correction into three elements.

[0020] According to the techniques described in the above-mentioned documents 1 and 2, it is possible to determine the change in the thermal efficiency of the boiler due to the influence of various factors by continuously comparing and measuring the load demand MWD value or other control value before and after feedback correction, and to acquire by self-learning the value of the correction coefficient for further correcting and optimizing the value after feedback correction based on the determination result.

[0021] On the other hand, the fuel function FX, which defines the relationship between the load demand MWD and the corresponding boiler input command value BID as a function, i.e., a curve, is set to reflect the characteristics of the boiler, and in the techniques described in the above-mentioned documents 1 and 2, it is set as a fixed value calculated in advance based on the accumulation of past actual measurement data. However, the behavior of the main steam pressure based on the characteristics of the boiler differs from one boiler to another, and further, it may change even in a single boiler due to the renewal of the boiler equipment. In other words, there may be a very slight deviation between the actual behavior of the main steam pressure and the value that should be, i.e., the optimal value, assumed in the fuel function FX. This deviation causes the fuel input amount to destabilize the boiler combustion control process, resulting in energy loss.

[0022] Therefore, for example, International Publication No. 2018 / 212224 (Patent Document 1) describes that in order to further improve the accuracy of control, in a boiler combustion control system, deviation from an optimal value assumed by a fuel function FX in the behavior of the main steam pressure is detected, and the fuel function FX is corrected autonomously and self-containedly. In other words, this technology corrects a reference curve that is the basis and starting point of self-learning by AI (Artificial Intelligence). This reference curve shows the initial value of the relationship between the load demand MWD and the boiler input command value BID specified for the target boiler.

[0023] In the techniques described in the above-mentioned documents 1 and 2, this reference curve is set as a fixed value calculated in advance based on the accumulation of past measured data, similar to the fuel function FX. In this case, depending on the boiler equipment renewal or other changes in the state, the behavior of the main steam pressure may slightly deviate from the optimal value assumed in the fuel function FX after correction by the fuel correction coefficient, causing the boiler combustion control process to become unstable and reducing efficiency.

[0024] In contrast, the boiler combustion control system described in Patent Document 1 constantly analyzes and judges the behavior and state changes of the boiler's main steam pressure based on past data, and adjusts the above-mentioned reference curve based on the judgment results to correct slight deviations that occur in the fuel function FX. Then, the boiler fuel control system performs this series of processes autonomously and in real time by a self-contained processing loop.

[0025] More specifically, the boiler combustion control system described in Patent Document 1 has a fuel correction coefficient calculation unit that calculates a fuel correction coefficient based on a ratio of load demand before and after feedback correction and a reference curve that defines an initial value of the relationship between the load demand and the fuel input amount, and a reference curve correction unit that outputs a reference curve correction coefficient for correcting the reference curve. The reference curve correction unit has a determination unit that calculates a deviation between a set main steam pressure and a measured main steam pressure and acquires a period and amplitude of the deviation, a reference curve correction coefficient output unit that calculates and outputs a reference curve correction coefficient based on a reference curve correction function, and a reference curve correction determination unit that corrects the reference curve correction function when the period and amplitude satisfy a predetermined condition.

[0026] However, even with the boiler combustion control system described in Patent Document 1, there is still room for improving the accuracy of boiler combustion control.

[0027] The present inventors have conducted extensive research in light of the above circumstances, and as a result have come up with the present invention. That is, in order to further improve the accuracy of boiler combustion control over the technology described in Patent Document 1, the boiler combustion control system according to the first embodiment of the present invention derives the proportional term and integral term in PID control from known parameters among the feedback correction amount of the fuel input amount obtained by PID control on the boiler facility side, and corrects the reference curve correction function based on the derived proportional term and integral term.

[0028] (Embodiment 1) Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In all the drawings for explaining the embodiment, the same or corresponding parts, circuits, or functional blocks are generally given the same reference numerals, and their repeated explanations will be omitted. On the other hand, parts etc. that have been described with reference numerals in one drawing may be referred to with the same reference numerals in the explanation of other drawings, although they will not be shown again.

[0029] <System configuration> 1 is a diagram illustrating an example of the configuration of a boiler combustion control system according to the first embodiment. As described above, the boiler combustion control system 1 is a device that determines a fuel correction coefficient K by adjusting a reference curve using an initial value and a fine-tuning function FXAI so that the amount of fuel input to the boiler 2 in the plant is optimized, and outputs the determined fuel correction coefficient K as control information to an existing circuit or the like that inputs fuel to the boiler 2. In other words, the boiler combustion control system 1 is a device that controls the combustion of the boiler 2 by substantially correcting the fuel function FX.

[0030] The boiler combustion control system 1 may be configured as a device implemented by hardware consisting of a semiconductor circuit, a microcomputer, etc. (not shown) that executes processes related to each function described later. Alternatively, the boiler combustion control system 1 may be configured by a general-purpose server device or a virtual server constructed on a cloud computing service, and may execute processes related to each function described later by executing middleware such as an OS (Operating System) and software running thereon, which are expanded from a recording device such as an HDD (Hard Disk Drive) to a memory, using a processor such as a CPU (Central Processing Unit) (not shown).

[0031] Moreover, the implementation by hardware and the implementation by software may be appropriately combined. Moreover, the configuration is not limited to the implementation in one housing, and some functions may be implemented in separate housings, and these housings may be connected to each other by a communication cable or the like. In other words, the implementation form of the boiler combustion control system 1 is not particularly limited, and it can be flexibly configured as appropriate according to the environment of the plant, etc.

[0032] FIG. 2 is a diagram showing an example of a configuration implemented by hardware and software of the boiler combustion control system according to the first embodiment of the present invention. As shown in FIG. 2, the boiler combustion control system 1 has a processor 151, a memory 152, a storage 153, an operation unit 154, a display unit 155, an interface 156, and a communication bus 157. The processor 151, the memory 152, the storage 153, the operation unit 154, the display unit 155, and the interface 156 are communicatively connected to the communication bus 157. A program PG is recorded in the storage 153. The processor 151 reads and executes the program PG to function as each functional block constituting the boiler combustion control system 1. The operation unit 154 is composed of, for example, a touch panel, a keyboard, a mouse, etc. The display unit 155 is composed of, for example, a liquid crystal panel, an organic EL panel, etc.

[0033] Returning to Fig. 1, we will continue to explain the configuration of the boiler combustion control system 1. As shown in Fig. 1, the boiler combustion control system 1 has various units, such as a division unit 11, a reference curve correction unit 12, a multiplication unit 13, and a fuel correction coefficient calculation unit 14, which are implemented by hardware or software. The system also has data such as an initial value and a fine adjustment function FXAI implemented as a file or table recorded in a memory, a HDD, or the like.

[0034] In the plant, main steam generated by burning fuel in a boiler 2 based on information on the fuel input amount (boiler input command value BID in the figure) is supplied to, for example, a steam turbine 3 and used for generating electricity using a generator (not shown). The load requirement MWD (input steam requirement) of the boiler 2 corresponding to the output of the generator is input, for example, via an operation panel (not shown) of the boiler 2 and is also input to the boiler combustion control system 1.

[0035] Meanwhile, for example, the pressure of the main steam generated in the boiler 2 is measured by a pressure gauge (not shown) provided in the boiler 2, and the measured value is input to the main steam pressure transmitter PX. The measured main steam pressure PV transmitted from the main steam pressure transmitter PX is input to the PID control unit 4, and the PID control unit 4 compares it with the set main steam pressure SV, which is the main steam pressure that should be. At this time, for example, if the fuel input amount is determined using a fuel function FX obtained under conditions in which the state of the boiler 2 (furnace dirt, etc.), fuel properties, and other factors are maintained, there is almost no difference between the measured main steam pressure PV and the set main steam pressure SV, and the desired load (generator output) is obtained by the fuel function FX. However, as described above, for example, a pressure difference may occur between the measured main steam pressure PV and the set main steam pressure SV due to changes in the state of the boiler 2, fuel properties, and other factors.

[0036] When the PID control unit 4 detects a pressure difference between the measured main steam pressure PV and the set main steam pressure SV, it calculates a feedback correction amount, i.e., a deviation (error amount) of the main steam pressure caused by a fuel shortage (or excess) by a known PID control method, and sends this to the adder unit 5. The adder unit 5 adds the feedback correction amount sent from the PID control unit 4 to the load demand amount MWD, which is also input to the boiler combustion control system 1, and outputs a load demand amount MWD' (boiler input command value BID') after feedback correction (the PID control unit 4 and the adder unit 5 may be referred to as a feedback control unit).

[0037] In the boiler combustion control system 1 of this embodiment, as described above, in order to follow deviation from an optimal value accompanying changes in characteristics such as the efficiency of the boiler 2, similarly to the technology described in Patent Document 1 and the like, an index indicating the degree of feedback correction operation by the feedback control unit (PID control unit 4 and adder unit 5), i.e., a ratio between the load demand MWD, which is the command value before and after the feedback correction, and the load demand MWD' (boiler input command value BID'), is calculated by a divider unit 11. Then, using this as an input, a fuel correction coefficient calculation unit 14 calculates a fuel correction coefficient K by self-learning and outputs it.

[0038] The output fuel correction coefficient K is multiplied by the load demand MWD' (boiler input command value BID') by the multiplication unit 6. This corrected load demand MWD" (boiler input command value BID") is input to the fuel input calculation unit 7, which converts it into a boiler input command value BID by the fuel function FX. The input of fuel to the boiler 2 is controlled based on this boiler input command value BID.

[0039] As for the calculation method of the fuel correction coefficient K in the fuel correction coefficient calculation unit 14 of the boiler combustion control system 1, the same method as that described in, for example, Patent Documents 1 and 2 can be appropriately used, and therefore a detailed description thereof will be omitted here. As described in Patent Documents 1 and 2, the connection relationship and processing order of each part of the plant including the boiler combustion control system 1 are not limited to those shown in FIG. 1, and various variations of configurations can be appropriately adopted within the scope of the same idea. For example, in the example of FIG. 1, the fuel correction coefficient K is multiplied by the load demand amount MWD' after feedback correction for correction, but the fuel correction coefficient K may be multiplied by the boiler input command value BID obtained by the fuel input amount calculation unit 7 for correction. Also, the fuel function FX may be directly corrected.

[0040] As described above, in determining the fuel correction coefficient K, self-learning is performed starting from the reference curve, but in the conventional technology, a fixed value set in advance is used for the reference curve. In this case, as the characteristics such as the efficiency of the boiler 2 change, the reference curve may also slightly deviate from the optimal value, causing the combustion control process of the boiler 2 to become unstable and the efficiency to decrease. Therefore, in this embodiment, the reference curve correction unit 12 constantly performs comparative measurement between the measured main steam pressure PV of the boiler 2 and the set main steam pressure SV, which is the set value that should be, to analyze and judge the change in the behavior of the main steam pressure of the boiler 2, and sets the reference curve correction coefficient KP based on the judgment result. Then, the multiplication unit 13 multiplies this by the initial value and the fine adjustment function FXAI, thereby correcting the initial value of the reference curve specified in the initial value and the fine adjustment function FXAI in real time.

[0041] Figure 3 shows an example of the behavior of the main steam pressure. Each figure shows an example of the fluctuation of the measured main steam pressure PV over time as a curve, and also shows the set main steam pressure SV as a straight line. The upper figure shows the case where the degree of correction (correction by the fuel correction coefficient K and integral correction by PID control) is set strong, and the measured main steam pressure PV fluctuates widely across the set main steam pressure SV. In contrast, the middle figure shows the case where the degree of correction is optimal, and the measured main steam pressure PV fluctuates near the set main steam pressure SV. On the other hand, the lower figure shows the case where the degree of correction is set weak, and the measured main steam pressure PV fluctuates widely and slowly across the set main steam pressure SV while repeating small fluctuations.

[0042] Here, in the boiler combustion control system 1 of this embodiment, the behavior of the main steam pressure is grasped by the oscillation of the measured main steam pressure PV based on the set main steam pressure SV, that is, the amplitude and period (the interval at which the measured main steam pressure PV crosses the set main steam pressure SV) centered on the set main steam pressure SV. The optimal state of the main steam pressure (measured main steam pressure PV) basically refers to a state in which the amplitude is small and the period is short, as shown in the middle diagram. Note that a long period means that the measured main steam pressure PV continues to deviate from the set main steam pressure SV for a long period of time, as shown in the bottom diagram.

[0043] As described above, if the fuel input amount is determined using the fuel function FX obtained under conditions in which the state of the boiler 2, the fuel properties, and other factors are maintained, there is almost no difference between the measured main steam pressure PV and the set main steam pressure SV. In reality, for example, as shown in the middle diagram of FIG. 4, the measured main steam pressure PV oscillates with a small amplitude around the set main steam pressure SV. However, a pressure difference (deviation) may occur between the measured main steam pressure PV and the set main steam pressure SV due to changes in the state of the boiler 2, the fuel properties, and other factors. In this embodiment, this deviation is measured to detect the timing when the measured main steam pressure PV is in an optimal state, that is, when the amplitude and period values ​​are small, and a correction coefficient for the fuel function FX (in this embodiment, the reference curve correction coefficient KP for the initial value and the fine-tuning function FXAI) is calculated based on the state at that time.

[0044] 4 is a diagram illustrating an example of the configuration of the reference curve correction unit 12 in the first embodiment. The reference curve correction unit 12 further includes, for example, a deviation determination unit 121, a period / amplitude determination unit 122, a reference curve correction determination unit 124, a reference curve correction coefficient output unit 125, a PID proportional term correction coefficient determination unit 1201, a PID integral term correction coefficient determination unit 1202, and other units implemented by hardware or software. The reference curve correction unit 12 also includes data such as a period history 126, an amplitude history 127, optimal value information 128, and a reference curve correction function VFX implemented as a file or table recorded in a memory, a HDD, or the like.

[0045] The measured main steam pressure PV and the set main steam pressure SV input to the reference curve correction unit 12 are input to a deviation determination unit 121, which calculates the difference (deviation) between them. The calculated difference is input to a period / amplitude determination unit 122, which calculates the period and amplitude of the fluctuations as information characterizing the behavior of the measured main steam pressure PV. As described above, the behavior of the measured main steam pressure PV is not constant but changes from moment to moment. Therefore, the period and amplitude are calculated as moving averages over a long period of time (e.g., 30 minutes). For this reason, the calculated period and amplitude information are recorded in a memory, HDD, etc. as period history 126 and amplitude history 127, respectively.

[0046] The calculated period and amplitude values ​​are input to the reference curve correction determination unit 124. The reference curve correction determination unit 124 determines whether the period and amplitude values ​​are optimal values ​​(including suitable values ​​within a certain range equivalent thereto). Information related to the optimal values ​​is recorded in a memory, HDD, etc., for example, as optimal value information 128. Then, when it is determined that the period and amplitude are in an optimal state, the value of the reference curve correction function VFX, which is set as a variable function, is moved until they deviate from the optimal state, and the reference curve correction function VFX is corrected.

[0047] On the other hand, the measured main steam pressure PV, the load demand MWD, and the boiler input command value BID input to the reference curve correction unit 12 are input to a PID proportional term correction coefficient determination unit 1201 and a PID integral term correction coefficient determination unit 1202, respectively.

[0048] The PID proportional term correction coefficient determination unit 1201 determines, by a predetermined calculation based on the input measured main steam pressure PV, load demand MWD, and boiler input command value BID, the deviation from an appropriate correction amount for the proportional term in PID control, among the feedback correction amounts for the fuel input amount determined by the PID control unit 4. Then, the PID proportional term correction coefficient determination unit 1201 determines a correction coefficient K1 for correcting the reference curve correction function VFX in order to correct the determined deviation in the correction amount for the proportional term.

[0049] Furthermore, the PID integral term correction coefficient determination unit 1202 determines, by a predetermined calculation based on the input measured main steam pressure PV, load demand MWD, and boiler input command value BID, the deviation from an appropriate correction amount for the correction amount related to the integral term in PID control, among the feedback correction amounts for the fuel input amount determined by the PID control unit 4. Then, the PID integral term correction coefficient determination unit 1202 determines a correction coefficient K2 for correcting the reference curve correction function VFX in order to correct the determined deviation in the correction amount related to the integral term.

[0050] The reference curve correction determination unit 124 corrects the reference curve correction function VFX based on the determined correction coefficients K1 and K2. Note that the correction based on this correction coefficient is performed independently of the correction based on the period and amplitude of fluctuations in the deviation between the measured main steam pressure PV and the set main steam pressure SV described above. In addition, the process for performing both of these corrections on the reference curve correction function VFX is repeatedly performed while the boiler input command value BID or the measured main steam pressure PV changes from moment to moment.

[0051] The reference curve correction coefficient output unit 125 acquires and outputs a reference curve correction coefficient KP corresponding to the load demand MWD based on the reference curve correction function VFX. The reference curve correction coefficient KP is multiplied by the initial value and the fine-tuning function FXAI to correct the initial value and the fine-tuning function FXAI.

[0052] <Correction process of reference curve (initial value and fine-tuning function FXAI)> FIG. 5 is a flow diagram showing an example of a process flow for correcting a reference curve in the first embodiment. As described above, the reference curve corresponds to the initial value and the fine-tuning function FXAI. Here, the process flow up to the part where the reference curve correction function VFX is set in the reference curve correction determination unit 124 of the reference curve correction unit 12 is shown. After that, the reference curve correction coefficient output unit 125 of the reference curve correction unit 12 acquires and outputs the reference curve correction coefficient KP corresponding to the load demand MWD based on the set reference curve correction function VFX. Note that there are two types of processes for correcting the reference curve, a reference curve first correction process and a reference curve second correction process, which are performed independently. Hereafter, the reference curve first correction process will be described, and then the reference curve second correction process will be described.

[0053] <<First base curve correction process>> As shown in FIG. 5, first, the deviation judgment unit 121 acquires the set main steam pressure SV (S01). The set main steam pressure SV may be preset in the system as a constant as shown in FIG. 1, or may be acquired as an external input from the boiler 2 or the like. Then, the measured main steam pressure PV transmitted from the main steam pressure transmitter PX is acquired (S02). The above processing order is an example, and the processing may be executed in the reverse order or in parallel. When the set main steam pressure SV and the measured main steam pressure PV are acquired, a deviation process is performed to obtain the difference between them (S03). The deviation judgment unit 121 inputs information on the calculated difference to the period / amplitude judgment unit 122 and the amplitude judgment unit 123, respectively, and returns to step S01 to continue the processing.

[0054] Based on the information on the difference in the main steam pressure obtained from the deviation determining unit 121, the period / amplitude determining unit 122 measures the period of the fluctuation of the measured main steam pressure PV based on the set main steam pressure SV (S11). For example, based on the history information of the past differences accumulated in a memory or the like (not shown), the timing at which the sign of the difference is reversed is grasped, and the time interval is taken as the period. As described above, the behavior of the measured main steam pressure PV is not constant but changes from moment to moment. Therefore, the period is calculated as a moving average based on the history of a long period of time (e.g., 30 minutes). Thereafter, it is determined whether the measured period is normal (whether it is an abnormal value such as a negative value). If it is not normal (is an abnormal value), the process returns to step S11 and the period measurement process is continued.

[0055] Similarly to the case of the period, the period / amplitude determination unit 122 measures the amplitude of fluctuations in the measured main steam pressure PV relative to the set main steam pressure SV, based on information on the difference in the main steam pressure obtained from the deviation determination unit 121 (S11). For example, the absolute value of the difference is grasped as the amplitude. The amplitude is also calculated as a moving average of historical information over a long period of time (e.g., 30 minutes). Thereafter, it is determined whether the measured amplitude is normal. If it is not normal, the process returns to step S11 and the amplitude measurement process continues.

[0056] If both the period and amplitude values ​​are normal, the calculated period and amplitude values ​​are input to the reference curve correction determination unit 124. Then, the reference curve correction determination unit 124 performs a first correction process (S20) of the reference curve correction function VFX.

[0057] Here, the first correction process (S20) of the standard curve correction function performed by the standard curve correction determining unit 124 will be described in detail.

[0058] Fig. 6 is a diagram showing an example of the flow of the first correction process of the reference curve correction function in the first embodiment. As shown in Fig. 6, first, the reference curve correction determination unit 124 acquires the transition of the period within a certain past time range (for example, 5 minutes) (S21), and determines whether each period falls within a predetermined range (S22). If it does not fall within the predetermined range (S22: N), nothing is done, or if the correction process for the reference curve correction function VFX has already been performed, it is terminated (S28).

[0059] On the other hand, if the period within the past certain time range falls within the predetermined range (S22: Y), it is determined whether the measured period and amplitude are the minimum values ​​so far in the history of past fluctuations (S23). Information on the minimum values ​​so far may be recorded, for example, in the optimum value information 128. It is to be noted that the period is determined to be the minimum value while being within the predetermined range in step S32. If at least one of the period and the amplitude is not the minimum value (S23: N), nothing is done, or if the correction process for the reference curve correction function VFX has already been performed, it is terminated (S28).

[0060] On the other hand, if both the measured period and amplitude are the minimum values ​​(S23:N), period and amplitude information relating to the previous optimum values ​​is obtained from the optimum value information 128 (S24), and a comparison is made with this to determine whether the combination of the measured period and amplitude is the optimum value (S25). A suitable method for determining which is the optimum value can be used, for example, by determining that the smaller period is the optimum value while the amplitude value is within a predetermined range. If the combination of the measured period and amplitude is not the optimum value (S25:N), nothing is done, or if the correction process for the reference curve correction function VFX has already been performed, this is terminated (S28).

[0061] On the other hand, if the combination of the measured period and amplitude is the optimum value (S25: Y), the contents of the optimum value information 128 are updated by this combination (S26), and a correction process for the reference curve correction function VFX is started (S27). The reference curve correction function VFX is set as a variable function that specifies a curve of the correspondence relationship between the load demand MWD and the reference curve correction coefficient KP, which is a correction coefficient for the initial value and the fine adjustment function FXAI, and is corrected by moving this curve by a predetermined amount. This correction continues, for example, until the measured period and amplitude deviate from the optimum state. Note that such a correction method is one example, and a method of correcting the reference curve correction function VFX (or the initial value and the fine adjustment function FXAI) using another index such as the boiler input command value BID in the control state when the combination of the measured period and amplitude is the optimum value may be used.

[0062] <<Second correction process of the reference curve correction function>> As shown in FIG. 5, the PID proportional term correction coefficient determination unit 1201 acquires the load demand amount MWD, the measured main steam pressure PV, and the boiler input command value BID (S31, S32, S33). The order in which these pieces of information are acquired is not particularly limited, and they may be acquired in parallel. The PID proportional term correction coefficient determination unit 1201 determines the PID proportional term correction coefficient K1 based on these pieces of acquired information (S34). The details of the process (S34) for determining the PID integral term correction coefficient K2 will be described later. The PID proportional term correction coefficient determination unit 1201 inputs the information of the determined PID proportional term correction coefficient K1 to the reference curve correction determination unit 124, and returns to step S31 to continue the process.

[0063] Similarly, the PID integral term correction coefficient determination unit 1202 acquires the load demand amount MWD, the measured main steam pressure PV, and the boiler input command value BID (S41, S42, S43). Note that the order in which these pieces of information are acquired is not particularly limited, and they may be acquired in parallel. The PID integral term correction coefficient determination unit 1202 determines the PID integral term correction coefficient K2 based on the acquired information (S44). Details of the process (S44) for determining the PID integral term correction coefficient K2 will be described later. The PID integral term correction coefficient determination unit 1202 inputs the information on the determined PID integral term correction coefficient K2 to the reference curve correction determination unit 124 and returns to step S41 to continue the process.

[0064] The reference curve correction determination unit 124 corrects the reference curve correction function VFX based on the acquired PID proportional term correction coefficient K1 and PID integral term correction coefficient K2 (S50). Details of the process (S50) for correcting the reference curve correction function VFX based on the PID proportional term correction coefficient K1 and the PID integral term correction coefficient K2 will be described later.

[0065] <<<Process for determining the PID proportional term correction coefficient K1>>> Here, details of the process for determining the PID proportional term correction coefficient K1 by the PID proportional term correction coefficient determination unit 1201 will be described.

[0066] FIG. 7 is a flowchart showing an example of the flow of the process for determining the PID proportional term correction coefficient K1. FIG. 8 is a diagram for explaining the process for determining the PID proportional term correction coefficient K1. As shown in FIG. 7, the PID proportional term correction coefficient determination unit 1201 calculates the main steam pressure correction amount ΔPTMV (S341). Since the boiler input command value BID = load demand amount MWD + main steam pressure correction amount ΔPTMV holds, the main steam pressure correction amount ΔPTMV is calculated by subtracting the load demand amount MWD from the boiler input command value BID.

[0067] Next, the PID proportional term correction coefficient determination unit 1201 multiplies the calculated main steam pressure correction amount ΔPTMV by the actual fuel amount (minus the water-fuel ratio) to calculate a relative fuel amount (engineering value) ΔFFRC required for the actual main steam pressure correction amount ΔPTMV (S342). The relative fuel amount is a relative fuel flow rate corresponding to the correction amount of the main steam pressure.

[0068] Next, the PID proportional term correction coefficient determination unit 1201 calculates a relative fuel amount moving average ΔFFRC-MAV, which is a moving average of the calculated relative fuel amount ΔFFRC within a predetermined time (S343). The relative fuel amount moving average ΔFFRC-MAV is set to, for example, a moving average of the relative fuel amount ΔFFRC for 20 minutes. This allows the calculation of a relative fuel amount that is close to the actual amount, in which fluctuations in the relative fuel amount ΔFFRC are cancelled out. Note that calculating this relative fuel amount moving average ΔFFRC-MAV is equivalent to finding the midpoint of the main steam pressure correction amount ΔPTMV.

[0069] Next, the PID proportional term correction coefficient determination unit 1201 calculates the measured main steam pressure moving average PV-MAV, which is a moving average of the measured main steam pressure PV within a predetermined time (S344). Note that this measured main steam pressure moving average PV-MAV can be said to represent the degree of influence of the main steam pressure on the relative fuel amount moving average ΔFFRC-MAV calculated in step S343.

[0070] Next, the PID proportional term correction coefficient determination unit 1201 divides the relative fuel amount moving average ΔFFRC-MAV by the measured main steam pressure moving average PV-MAV to calculate the ratio of the relative fuel amount ΔFFRC to the measured main steam pressure PV as the weight W1 (S345).

[0071] Next, the PID proportional term correction coefficient determination unit 1201 acquires a delay time Δt1, which is the time required for the varying part of the relative fuel quantity ΔFFRC to appear as the varying part of the measured main steam pressure PV. The delay time Δt1 is calculated, for example, in the process of determining the PID integral term correction coefficient described later. As shown in FIG. 8, the PID proportional term correction coefficient determination unit 1201 shifts the curve representing the varying part of the measured main steam pressure PV by the delay time Δt1 in the reverse direction of the time axis to cancel the delay time Δt1, and then divides the amplitude in the varying part of the measured main steam pressure PV by the amplitude in the varying part of the relative fuel quantity ΔFFRC. Thereby, the correction strength J1 of the correction part related to the proportional term in the PID control of the main steam pressure correction amount ΔPTMV is obtained (S346).

[0072] Next, the PID proportional term correction coefficient determination unit 1201 divides the correction strength J1 obtained in step S346 by the weight W1 obtained in step S345 to calculate the correction coefficient of the correction related to the proportional term in the PID control, that is, the PID proportional term correction coefficient K1 (S347).

[0073] <<<Process of determining the PID integral term correction coefficient K2>>> Next, the details of the process of determining the PID integral term correction coefficient K2 by the PID integral term correction coefficient determination unit 1202 will be described.

[0074] FIG. 9 is a flowchart showing an example of the flow of the process of determining the PID integral term correction coefficient K2. FIG. 10 is a diagram for explaining the process of determining the PID integral term correction coefficient K2. As shown in FIG. 9, the PID integral term correction coefficient determination unit 1202 starts time measurement when the relative fuel quantity ΔFFRC crosses its midpoint in a predetermined direction (S441). For example, as shown in FIG. 10, time measurement is started when the relative fuel quantity ΔFFRC crosses its midpoint from above (positive side) to below (negative side).

[0075] Next, the PID integral term correction coefficient determination unit 1202 ends the time measurement when the measured main steam pressure PV crosses its midpoint in the above-mentioned predetermined direction (S442). For example, as shown in Fig. 10, the time measurement ends when the measured main steam pressure PV crosses from the top (positive side) to the bottom (negative side).

[0076] Next, the PID integral term correction coefficient determination unit 1202 calculates the time from the start to the end of the time measurement as the delay time Δt1 (S443).

[0077] Next, PID integral term correction coefficient determination unit 1202 calculates a time lag T1 between the value of the integral term in the PID control of the existing main steam pressure correction amount ΔPTMV and the delay time Δt1 calculated in step S443 (S444).

[0078] Next, the PID integral term correction coefficient determination unit 1202 calculates a correction coefficient for the correction related to the integral term in PID control, i.e., a PID integral term correction coefficient K2, by comparing the time lag T1 calculated in step S444 with the delay time Δt1 calculated in step S443 (S445).

[0079] <<<Second correction process of the reference curve correction function>>> Here, the second correction process (S50) of the standard curve correction function performed by the standard curve correction determining unit 124 will be described in detail.

[0080] FIG. 11 is a diagram showing an example of the flow of the second correction process of the reference curve correction function. As shown in FIG. 11, the reference curve correction determination unit 124 first acquires a PID proportional term correction coefficient K1 and a PID integral term correction coefficient K2 (S51). Next, the reference curve correction determination unit 124 adds the PID proportional term correction coefficient K1 and the PID integral term correction coefficient K2 to obtain a correction coefficient K12 (S52). Next, the reference curve correction determination unit 124 multiplies the correction coefficient K12 by the adjustment coefficient Ka to obtain a correction coefficient K3 (S53). After that, the reference curve correction determination unit 124 multiplies the correction coefficient K3 by the reference curve correction function VFX to obtain a new corrected reference curve correction function VFX (S54).

[0081] After the reference curve correction function VFX is corrected by the above processing, the reference curve correction coefficient output unit 125 at the subsequent stage acquires and outputs the reference curve correction coefficient KP based on the reference curve correction function VFX at this point.

[0082] According to the first embodiment, in the boiler combustion control system, the deviation of the correction amounts related to the proportional and integral terms of the main steam pressure correction amount ΔPTMV by PID control from the appropriate values ​​is quantified, and the reference curve correction function is corrected so as to reduce the deviation. As a result, the situation related to the basis of the main steam pressure correction can be grasped in almost real time, the correction amount of the main steam pressure can be further optimized, and the combustion control can be further improved.

[0083] (Embodiment 2) A boiler combustion control system according to the second embodiment will be described. The boiler combustion control system according to the present embodiment is based on the boiler combustion control system according to the first embodiment, and further has a function of weighting the correction strength of the reference curve correction function based on the unburned matter in the ash of the boiler measured during combustion of the boiler. The unburned matter in the ash is an index value that indicates the ratio of unburned matter, that is, matter that remains unburned, to the ash remaining after fuel is burned in the boiler. The unburned matter in the ash is important information that allows the combustion state of the boiler to be known. By acquiring the unburned matter in the ash almost in real time and changing the correction strength of the reference curve according to the value, it is possible to further improve the accuracy of combustion control in the boiler combustion control system.

[0084] Fig. 12 is a diagram illustrating an example of the configuration of a boiler combustion control system according to the second embodiment. As illustrated in Fig. 12, the boiler combustion control system 1 acquires the unburned content Z in the ash of the boiler 2 measured by the unburned content Z in the ash measuring instrument 8. The unburned content Z in the ash measuring instrument 8 repeatedly measures the unburned content Z in the ash almost in real time during combustion in the boiler 2, and inputs the measured value to the reference curve correction unit 12. The reference curve correction unit 12 effectively weights the correction strength of the reference curve based on the acquired unburned content Z in the ash, and outputs the reference curve correction coefficient KP using the reference curve correction function VFX corrected by the weighted correction strength.

[0085] Fig. 13 is a diagram illustrating an example of the configuration of the reference curve correction unit 12 in the embodiment 2. Fig. 14 is a diagram illustrating an example of the flow of processing in the reference curve correction unit 12 in the embodiment 2.

[0086] As shown in Fig. 13, the base curve correction unit 12 acquires the input unburned content in ash Z in addition to the determined PID proportional term correction coefficient K1 and PID integral term correction coefficient K2. Also, as shown in Fig. 14, the base curve correction determination unit 124 of the base curve correction unit 12 performs a second correction process of the base curve correction function VFX in consideration of the magnitude of the acquired value of the unburned content in ash Z (S60). Details of the second correction process (S60) of the base curve correction function VFX in the second embodiment will be described below.

[0087] FIG. 15 is a diagram showing an example of the flow of the second correction process of the reference curve correction function VFX in the second embodiment. As shown in FIG. 15, the reference curve correction determination unit 124 acquires the PID proportional term correction coefficient K1, the PID integral term correction coefficient K2, and the unburned fuel in ash Z (S61). Next, the reference curve correction determination unit 124 adds the PID proportional term correction coefficient K1 and the PID integral term correction coefficient K2 to obtain the correction coefficient K12 (S62). Next, a weighting coefficient KW according to the value of the unburned fuel in ash Z is determined (S63). To determine the weighting coefficient KW, for example, a preset weighting function is used or a weighting table stored in advance is referenced.

[0088] Fig. 16 is a diagram showing an example of a weighting function in the second embodiment. As shown in Fig. 16, the weighting function FW is a function that shows the relationship between the unburned content Z in the ash and the weighting factor KW as a straight line or a curve. In the weighting function FW, the weighting factor KW is uniquely determined using the unburned content Z in the ash as an input parameter. In this example, when the value of the unburned content Z in the ash is 5.0(%), the weighting factor KW is 1.00, and when the value of the unburned content Z in the ash is 10.0(%), the weighting factor KW is 1.50.

[0089] Fig. 17 is a diagram showing an example of a weighting table in the second embodiment. As shown in Fig. 17, the weighting table TB is a table in which the value of the weighting coefficient KW is associated with each discrete value of the unburned content Z in the ash. The discrete values ​​of the unburned content Z in the ash in the weighting table TB may be set according to the measurement resolution of the unburned content Z in the ash measuring instrument 8, or may be set according to the value obtained by rounding off, rounding down, or rounding up the value of the unburned content Z in the ash obtained from the unburned content Z in the ash measuring instrument 8 to a predetermined decimal place.

[0090] Next, the reference curve correction determination unit 124 obtains a correction coefficient K3 by multiplying the correction coefficient K12, the adjustment coefficient Ka, and the weighting coefficient KW (S64). After that, the reference curve correction determination unit 124 obtains a new corrected reference curve correction function VFX by multiplying the correction coefficient K3 by the reference curve correction function VFX (S65).

[0091] According to the second embodiment, the correction coefficient is weighted based on the unburned content in the ash during combustion in the boiler, and the reference curve correction function is corrected using the weighted correction coefficient. This makes it possible to reflect the combustion state of the boiler in the correction almost in real time, thereby further improving the accuracy of boiler combustion control.

[0092] As described above, according to the boiler combustion control system 1 of the first embodiment of the present invention, the deviation of the fluctuation of the measured main steam pressure PV from the set main steam pressure SV is measured as a period and an amplitude, and the timing when the period and the amplitude are in an optimal state is identified based on the long-term transition. Then, based on the state when the period and the amplitude are optimal, the reference curve correction coefficient KP for correcting the fuel function FX (specifically, the initial value and the fine-tuning function FXAI in this embodiment) is output. That is, it is possible to autonomously and self-containedly correct a slight deviation occurring in the fuel function FX in real time.

[0093] (Embodiment 2) Next, a description will be given of embodiment 2. In the following, as a rule, descriptions of points that overlap with the above-mentioned embodiment will be omitted.

[0094] In this embodiment, a boiler combustion control system applicable to a supercritical pressure once-through boiler or an ultra-supercritical pressure once-through boiler will be described. The fuel input amount and the water feed amount in a supercritical pressure once-through boiler or an ultra-supercritical pressure once-through boiler depend on the main steam pressure and the water-fuel ratio. The water-fuel ratio is a value defined by the weight ratio of the water feed amount to the boiler and the fuel. This water-fuel ratio is controlled by a water-fuel ratio master provided outside the boiler combustion control system. The water-fuel ratio master adjusts the fuel input amount while performing an integration process according to the heat amount (main steam pressure). However, in the past, it was not possible to appropriately control the fuel input amount, and combustion could not be stabilized.

[0095] Therefore, an object of this embodiment is to provide a boiler combustion control system etc. capable of appropriately controlling the amount of fuel input in a supercritical pressure once-through boiler or an ultra-supercritical pressure once-through boiler.

[0096] The invention made by the present inventor has been specifically described above based on the embodiment, but it goes without saying that the present invention is not limited to the above embodiment and can be modified in various ways without departing from the gist of the invention. For example, the above embodiment has been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those having all of the configurations described. In addition, it is possible to add, delete, or replace part of the configuration of the above embodiment with other configurations.

[0097] In addition, the above-mentioned configurations, functions, processing units, processing means, etc. may be realized in part or in whole by hardware, for example, by designing them as integrated circuits. In addition, the above-mentioned configurations, functions, etc. may be realized in software by a processor interpreting and executing a program that realizes each function. Information such as the program, table, file, etc. that realizes each function can be stored in a recording device such as a memory, a hard disk, or an SSD (Solid State Drive), or in a recording medium such as an IC card, an SD card, or a DVD.

[0098] In addition, in each of the above figures, the control lines and information lines are shown as those considered necessary for explanation, and do not necessarily show all the control lines and information lines in the actual implementation. In reality, it can be considered that almost all the components are connected to each other. [Industrial Applicability]

[0099] The present invention can be used in a boiler combustion control system that determines the amount of fuel input to a boiler based on the load requirement of the boiler, a boiler combustion control method, a program therefor, and a tangible computer-readable recording medium on which the program is non-temporarily recorded, etc. [Explanation of symbols]

[0100] 1,201...boiler combustion control system, 2...boiler, 3...steam turbine, 4...PID control unit, 5...addition unit, 6...multiplication unit, 7...fuel input amount calculation unit, 8...unburned content meter in ash, 11...division unit, 12...reference curve correction unit, 13...multiplication unit, 14...fuel correction coefficient calculation unit, 121...deviation determination unit, 122...period / amplitude determination unit, 124...reference curve correction determination unit, 125...reference curve correction coefficient output unit, 126...period history, 127...amplitude history, 128...optimum value information, 151...processor, 152...memory, 153...storage, 154...operation unit, 155...display unit, 156...interface, 157...communication bus, 1201...PID proportional term correction coefficient Determination section, 1202...PID integral term correction coefficient determination section, SV...set main steam pressure, PV...measured main steam pressure, PV-MAV...moving average of measured main steam pressure, PX...main steam pressure transmitter, MWD, MWD', MWD”...load demand, BID, BID', BID”...boiler input command value, J1...PID proportional term correction strength, K...fuel correction coefficient, K1...PID proportional term correction coefficient, K2...PID integral term correction coefficient, KP...reference curve correction coefficient, FX...fuel function, FXAI...initial value and fine adjustment function, T1...time lag, VFX...reference curve correction function, W1...weighting, Z...unburned content in ash, ΔFFRC...relative fuel amount, ΔPTMV...main steam pressure correction amount, Δt1...delay time

Claims

1. 1. A boiler combustion control system comprising: a boiler supplying fuel relating to a fuel input amount to the boiler calculated based on a predetermined fuel function for a load demand amount, determining a feedback correction amount by PID control based on a measured main steam pressure that is a measured main steam pressure of the boiler and a set main steam pressure that is a preset main steam pressure of the boiler, and correcting the load demand amount or the fuel input amount based on the feedback correction amount, the boiler combustion control system outputting a fuel correction coefficient for correcting the load demand amount or the fuel input amount after the feedback correction, the boiler combustion control system comprising: a reference curve correction unit that calculates a correction amount of a proportional term and an integral term in the PID control among the feedback correction amounts based on a boiler input command value, the load demand or the fuel input amount, and the measured main steam pressure, and corrects a reference curve that defines a relationship between the load demand and the fuel input amount for the boiler based on the calculated correction amounts of the proportional term and the integral term; A fuel correction coefficient calculation unit that calculates the fuel correction coefficient based on the corrected reference curve. Boiler combustion control system.

2. 2. The boiler combustion control system according to claim 1, The reference curve correction unit a proportional term correction coefficient determination unit that determines a proportional term correction coefficient for correcting a reference curve correction function, which is a function used to correct the reference curve, based on a comparison result between an amplitude of a fluctuation in the proportional term correction amount and an amplitude of a fluctuation in the measured main steam pressure; and an integral term correction coefficient determination unit that determines an integral term correction coefficient for correcting the reference curve correction function based on a delay time until a change in the integral term correction amount is reflected in a change in the measured main steam pressure, correcting the reference curve correction function based on the determined proportional term correction coefficient and integral term correction coefficient; Boiler combustion control system.

3. 3. The boiler combustion control system according to claim 2, The reference curve correction unit correcting the reference curve correction function based on the unburned content in ash during combustion in the boiler measured by an unburned content in ash measuring device; Boiler combustion control system.

4. A boiler combustion control method in a boiler combustion control system, the method comprising: supplying to the boiler a fuel relating to a fuel input amount to the boiler calculated based on a predetermined fuel function for a load demand amount; determining a feedback correction amount by PID control based on a measured main steam pressure that is a measured main steam pressure of the boiler and a set main steam pressure that is a preset main steam pressure of the boiler; and outputting a fuel correction coefficient for correcting the load demand amount or the fuel input amount after the feedback correction to a plant that corrects the load demand amount or the fuel input amount based on the feedback correction amount, determining a correction amount of a proportional term and an integral term in the PID control, among the feedback correction amounts, based on a boiler input command value, the load requirement or the fuel input amount, and the measured main steam pressure; correcting a reference curve that defines a relationship between the load requirement and the fuel input amount for the boiler based on the obtained correction amounts of the proportional term and the integral term; and calculating the fuel correction factor based on the corrected reference curve. Boiler combustion control method.

5. A program used in a boiler combustion control system, which supplies a boiler with fuel relating to a fuel input amount to the boiler calculated based on a predetermined fuel function for a load demand, calculates a feedback correction amount by PID control based on a measured main steam pressure that is a measured main steam pressure of the boiler and a set main steam pressure that is a preset main steam pressure of the boiler, and corrects the load demand or the fuel input amount based on the feedback correction amount, outputs a fuel correction coefficient for correcting the load demand or the fuel input amount after the feedback correction, A processor provided in the boiler combustion control system, determining a correction amount of a proportional term and an integral term in the PID control, among the feedback correction amounts, based on a boiler input command value, the load requirement or the fuel input amount, and the measured main steam pressure; correcting a reference curve that defines a relationship between the load requirement and the fuel input amount for the boiler based on the obtained correction amounts of the proportional term and the integral term; calculating the fuel correction factor based on the corrected reference curve; program.

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