Fuel gas-steam combined cycle unit denitration system control method and system

Abstract

The invention discloses a gas-steam combined cycle unit denitration system control method and system, and relates to the technical field of gas turbine control, and the method comprises the steps: obtaining the operation parameters of the gas-steam combined cycle unit denitration system control process, and correcting the gas turbine load through the air temperature of the inlet of a gas compressor, calculating a load feed-forward control quantity and an exhaust flow feed-forward control quantity through a feed-forward function based on the corrected gas turbine load and gas turbine exhaust flow; calculating feedback control quantity through a PID (Proportion Integration Differentiation) controller on the basis of the nitrogen oxide concentration set value at the outlet of the waste heat boiler and the actual nitrogen oxide concentration; summing the feedforward control quantity and the PID feedback control quantity to obtain a feedforward-feedback control quantity, and correcting the feedforward-feedback control quantity through an SCR spray gun input rate correction function to obtain a final urea solution flow regulating valve instruction. The method disclosed by the invention has better effects in the aspects of rapidity, reliability and stability of the denitration control system.

Description

Technical Field

[0001] The present invention relates to the technical field of gas turbine control, and in particular to a control method and system for a denitration system of a gas-steam combined cycle unit. Background Art

[0002] As an efficient and flexible power generation technology, gas-steam combined cycle units have been widely used around the world in recent years. Their advantages are rapid start-up and shutdown, high efficiency, and strong ability to adapt to load changes. Especially when the demand in the electricity market fluctuates frequently, the peak-shaving capacity of combined cycle units is particularly important. With the continuous advancement of gas turbine technology, the turbine inlet temperature continues to increase. The turbine inlet temperature of modern gas turbines has exceeded 1300°C. However, high-temperature operation has led to a sharp increase in the generation rate of nitrogen oxides. In order to meet increasingly stringent environmental regulations, power plants generally use selective catalytic reduction (SCR) technology, which reduces NOx to harmless nitrogen and water under the action of catalysts by injecting reducing agents (such as ammonia or urea solution) into the flue, thereby achieving denitrification. However, the operation of the SCR system also faces a series of challenges, including the optimal use of urea solution and the stable control of nitrogen oxide concentrations.

[0003] Traditional SCR system control mainly relies on PID feedback control method, which continuously monitors the NOx concentration in the flue gas and adjusts the injection amount of urea solution. Although this method is simple, due to the inherent hysteresis of feedback control, when the unit operating conditions change, the adjustment of NOx concentration often cannot respond in time, resulting in large fluctuations in emission concentration over a long period of time. Especially under rapid load changes or other sudden operating conditions, NOx concentration may temporarily exceed the standard, increasing the risk of environmental emissions. In addition, the injection amount of urea solution in traditional methods is often adjusted after the fact. Excessive injection not only wastes resources, but may also cause corrosion of the flue gas channel. For units that lack exhaust flow measurement systems, other indirect parameters are usually used for speculation, which further increases the complexity and uncertainty of system control. Summary of the invention

[0004] In view of the above-mentioned problems, the present invention is proposed.

[0005] Therefore, the technical problems solved by the present invention are: the existing denitrification system control method has high response lag, large fluctuations in nitrogen oxide concentration, uneconomical use of urea solution, and how to accurately control the urea injection amount under rapid load changes to stabilize NOx emissions.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: a method for controlling a denitration system of a gas-steam combined cycle unit, comprising obtaining operating parameters of a control process of a denitration system of a gas-steam combined cycle unit, using the compressor inlet air temperature to correct the gas turbine load, and calculating a load feedforward control quantity and an exhaust flow feedforward control quantity through a feedforward function based on the corrected gas turbine load and the gas turbine exhaust flow; calculating a feedback control quantity through a PID controller based on a set value of a nitrogen oxide concentration at a waste heat boiler outlet and an actual nitrogen oxide concentration; summing the feedforward control quantity and the PID feedback control quantity to obtain a feedforward-feedback control quantity, and then correcting the feedforward-feedback control quantity through an SCR gun input rate correction function to obtain a final urea solution flow regulating valve instruction.

[0007] As a preferred scheme of the control method for the denitrification system of a gas-steam combined cycle unit described in the present invention, the operating parameters include the gas turbine exhaust flow rate EXF, the compressor inlet air temperature T1, the gas turbine load PGT, the set value of the nitrogen oxide concentration at the outlet of the waste heat boiler NOxSP, the actually measured nitrogen oxide concentration NOx at the outlet of the waste heat boiler, the number of SCR spray guns NU put into use, the total number of SCR spray guns NA, the urea solution flow control valve instruction MV0 calculated by PID feedback control, the load correction coefficient KGT, the gas turbine load PGT' after the compressor inlet air temperature is corrected, the load feedforward control amount FFGT, the exhaust flow feedforward control amount FFEXF, the SCR spray gun input rate R, the control valve instruction correction coefficient KMV, the feedforward-feedback control amount MV', and the final urea solution flow control valve instruction MV.

[0008] As a preferred solution of the control method for the denitration system of the gas-steam combined cycle unit of the present invention, the method of using the compressor inlet air temperature to correct the gas turbine load includes calculating the load correction coefficient KGT from the compressor inlet air temperature T1 through the correction function FX1, and correcting the gas turbine load PGT, which is expressed as:

[0009] KGT=FX1(T1)

[0010] PGT'=KGT×PGT

[0011] Among them, PGT' is the corrected gas turbine load.

[0012] As a preferred solution of the control method for the denitration system of a gas-steam combined cycle unit of the present invention, the calculation of the load feedforward control quantity and the exhaust flow feedforward control quantity by the feedforward function includes calculating the load feedforward control quantity FFGT by the feedforward function FX2 after the modified gas engine load PGT', which is expressed as:

[0013] FFGT=FX2(PGT′)

[0014] The exhaust flow rate EXF of the combustion engine is calculated by the feedforward function FX4 to calculate the exhaust flow rate feedforward control amount FFEXF, which is expressed as:

[0015] FFEXF=FX4(EXF)

[0016] The function curves of the correction function and the feedforward function are determined by the unit characteristics and on-site debugging.

[0017] As a preferred solution of the gas-steam combined cycle unit denitrification system control method described in the present invention, the nitrogen oxide concentration set value NOxSP and the actually measured nitrogen oxide concentration NOx are calculated by a PID controller to calculate the feedback control amount MV0.

[0018] As a preferred solution of the control method for the denitration system of the gas-steam combined cycle unit described in the present invention, wherein: the final urea solution flow control valve instruction is obtained by summing the feedforward control amount and the PID feedback control amount to obtain the feedforward-feedback control amount, and then the ratio of the number of SCR spray guns NU put into use to the total number of SCR spray guns NA is used as the SCR spray gun investment rate R, and the SCR spray gun investment rate R is obtained by the correction function FX3 to obtain the control valve instruction correction coefficient KMV, and the calculated feedforward-feedback control amount MV' is corrected by the control valve instruction correction coefficient KMV, which is expressed as:

[0019] MV′=MV0+FFGT+FFEXF

[0020]

[0021] KMV=FX3(R)

[0022] MV=KMV×MV′

[0023] MV is used as the urea solution flow control valve instruction to control the opening of the urea solution flow control valve. The urea solution flow control valves of different SCR spray guns all use MV as the valve instruction to maintain the same opening.

[0024] As a preferred solution of the control method for the denitration system of the gas-steam combined cycle unit of the present invention, the method of obtaining the final urea solution flow control valve instruction also includes replacing the gas engine exhaust flow with the IGV opening when the unit is not configured with the gas engine exhaust flow calculation logic or the calculated gas engine exhaust flow obviously deviates from the normal value. The gas engine exhaust flow obviously deviates from the normal value and is expressed as:

[0025] EXF≤0 or EXF>KF×EXF0

[0026] Among them, EXF0 is the design value of the exhaust flow of the gas turbine, which is provided by the gas turbine manufacturer. KF is the coefficient for judging whether the exhaust flow of the gas turbine deviates from the normal value, KF=2; IGV represents the IGV opening, FFIGV0 represents the IGV feedforward control amount before the compressor inlet air temperature is corrected, KIGV represents the correction coefficient of the IGV feedforward control amount, FFIGV represents the IGV feedforward control amount, and the feedforward control amount FFIGV0 before the compressor inlet air temperature is corrected is calculated by the IGV opening through the feedforward function FX5. The correction coefficient KIGV of the IGV feedforward control amount is calculated by the compressor inlet air temperature T1 through the correction function FX6. KIGV is used to correct FFIGV0 to obtain the IGV feedforward control amount FFIGV, which is expressed as:

[0027] FFIGV0=FX5(IGV)

[0028] KIGV=FX6(T1)

[0029] FFIGV=KIGV×FFIGV0

[0030] The final urea solution flow control valve command MV is expressed as:

[0031] MV′=MV0+FFGT+FFIGV

[0032] MV=KMV×MV′

[0033] The calculated MV is used to control the opening of the urea solution flow regulating valve and control the nitrogen oxide concentration at the waste heat boiler outlet.

[0034] Another object of the present invention is to provide a control system for a denitrification system of a gas-steam combined cycle unit, which obtains a feedforward-feedback control quantity by summing a feedforward control quantity and a PID feedback control quantity, and then corrects the feedforward-feedback control quantity through an SCR spray gun input rate correction function to obtain a final urea solution flow regulating valve instruction, thereby solving the problems of poor control effect and large fluctuations in nitrogen oxide concentration in the current denitrification system.

[0035] As a preferred solution of the control system of the denitration system of the gas-steam combined cycle unit described in the present invention, it includes: a data acquisition module, a feedforward control quantity calculation module, a feedback control quantity calculation module, and a control quantity correction module; the data acquisition module is used to obtain the operating parameters required for the control process of the denitration system of the gas-steam combined cycle unit; the feedforward control quantity calculation module is used to correct the gas turbine load using the compressor inlet air temperature, and calculate the load feedforward control quantity and the exhaust flow feedforward control quantity through the feedforward function based on the corrected gas turbine load and the gas turbine exhaust flow; the feedback control quantity calculation module is used to calculate the feedback control quantity through the PID controller based on the set value of the nitrogen oxide concentration at the outlet of the waste heat boiler and the actual nitrogen oxide concentration; the control quantity correction module is used to sum the feedforward control quantity and the PID feedback control quantity to obtain the feedforward-feedback control quantity, and then correct the feedforward-feedback control quantity through the SCR spray gun input rate correction function to obtain the final urea solution flow regulating valve instruction.

[0036] A computer device comprises a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of a method for controlling a denitration system of a gas-steam combined cycle unit.

[0037] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of a method for controlling a denitration system of a gas-steam combined cycle unit.

[0038] Beneficial effects of the present invention: The control method for the denitrification system of a gas-steam combined cycle unit provided by the present invention introduces feedforward of the engine load and the engine exhaust flow rate. When the engine operating condition changes, before causing a change in the nitrogen oxide concentration at the outlet of the waste heat boiler, the urea solution flow control valve is adjusted in advance according to changes in the engine load and the engine exhaust flow rate, and the urea flow rate sprayed into the waste heat boiler is adjusted; for units that are not configured with engine exhaust flow calculation logic or the calculated engine exhaust flow rate is significantly deviated from the normal value, the engine exhaust flow rate is replaced by the IGV opening, and the urea solution flow control valve is adjusted in advance according to changes in the engine load and the IGV opening; the feedforward control amount is corrected according to the compressor inlet air temperature, the control instruction is corrected according to the SCR spray gun input rate, and the correction of the current operating condition boundary parameters is introduced into the control algorithm to improve the control effect. The present invention achieves better results in terms of rapidity, reliability, efficiency and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0040] Figure 1 An overall flow chart of a gas-steam combined cycle unit denitrification system control method provided for the first embodiment of the present invention.

[0041] Figure 2 A denitration system control logic diagram of a denitration system control method for a gas-steam combined cycle unit provided in the first embodiment of the present invention.

[0042] Figure 3 This is an example diagram of a correction function FX1 of a gas-steam combined cycle unit denitration system control method provided in the first embodiment of the present invention.

[0043] Figure 4 This is an example diagram of a feedforward function FX2 of a gas-steam combined cycle unit denitration system control method provided in the first embodiment of the present invention.

[0044] Figure 5 This is an example diagram of a feedforward function FX4 of a gas-steam combined cycle unit denitration system control method provided in the first embodiment of the present invention.

[0045] Figure 6 This is an example diagram of a correction function FX3 of a gas-steam combined cycle unit denitration system control method provided in the first embodiment of the present invention.

[0046] Figure 7 A control logic diagram after replacing the exhaust flow of the gas turbine with the opening of the IGV in a denitration system control method for a gas-steam combined cycle unit provided in the first embodiment of the present invention.

[0047] Figure 8 This is an example diagram of a feedforward function FX5 of a gas-steam combined cycle unit denitration system control method provided in the first embodiment of the present invention.

[0048] Fig. 9 This is an example diagram of the correction function FX6 of a gas-steam combined cycle unit denitration system control method provided in the first embodiment of the present invention.

[0049] Fig.10 An overall flow chart of a control system for a gas-steam combined cycle unit denitrification system provided in accordance with the third embodiment of the present invention. DETAILED DESCRIPTION

[0050] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0051] Example 1, reference Figure 1-Figure 9 , which is an embodiment of the present invention, provides a method for controlling a denitration system of a gas-steam combined cycle unit, comprising:

[0052] S1: Obtain the operating parameters of the denitration system control process of the gas-steam combined cycle unit, use the compressor inlet air temperature to correct the gas turbine load, and calculate the load feedforward control amount and the exhaust flow feedforward control amount through the feedforward function based on the corrected gas turbine load and gas turbine exhaust flow.

[0053] Further, refer to Figure 2 The operating parameters include the gas turbine exhaust flow EXF, the compressor inlet air temperature T1, the gas turbine load PGT, the set value of the nitrogen oxide concentration at the waste heat boiler outlet NOxSP, the actually measured nitrogen oxide concentration NOx at the waste heat boiler outlet, the number of SCR spray guns NU put into use, the total number of SCR spray guns NA, the urea solution flow control valve instruction MV0 calculated by PID feedback control, the load correction coefficient KGT, the gas turbine load PGT' after the compressor inlet air temperature correction, the load feedforward control amount FFGT, the exhaust flow feedforward control amount FFEXF, the SCR spray gun input rate R, the control valve instruction correction coefficient KMV, the feedforward-feedback control amount MV', and the final urea solution flow control valve instruction MV.

[0054] It should be noted that the reference Figure 3 The use of the compressor inlet air temperature to correct the gas turbine load includes calculating the load correction coefficient KGT from the compressor inlet air temperature T1 through the correction function FX1, and correcting the gas turbine load PGT, which is expressed as:

[0055] KGT=FX1(T1)

[0056] PGT'=KGT×PGT

[0057] Among them, PGT' is the corrected gas turbine load.

[0058] It should also be noted that the reference Figure 4 Calculating the load feedforward control quantity and the exhaust flow feedforward control quantity by the feedforward function includes calculating the load feedforward control quantity FFGT by the feedforward function FX2 after the modified engine load PGT', which is expressed as:

[0059] FFGT=FX2(PGT′)

[0060] refer to Figure 5 , the exhaust flow rate EXF of the combustion engine is calculated by the feedforward function FX4 to calculate the exhaust flow rate feedforward control amount FFEXF, which is expressed as:

[0061] FFEXF=FX4(EXF)

[0062] The function curves of the correction function and the feedforward function are determined by the unit characteristics and on-site debugging.

[0063] It should also be noted that by using the correction function to correct the gas turbine load, the influence of ambient temperature in actual operating conditions can be accurately considered; specifically, the load correction coefficient KGT calculated by the compressor inlet air temperature T1 and the correction function FX1 can effectively correct the gas turbine load PGT, thereby obtaining the corrected load PGT'. Since the gas turbine load is greatly affected by the ambient temperature, this correction can eliminate the influence of ambient temperature on the gas turbine load and more accurately describe the feedforward relationship of the gas turbine load to the denitrification system, thereby improving the response speed and control accuracy of the denitrification system.

[0064] It should also be noted that based on the corrected gas turbine load PGT' and the gas turbine exhaust flow EXF, the load feedforward control quantity FFGT and the exhaust flow feedforward control quantity FFEXF are calculated respectively through the feedforward functions FX2 and FX4, and the urea solution flow is adjusted in advance before the unit operating conditions change and before the nitrogen oxide concentration at the waste heat boiler outlet changes; the introduction of this feedforward control mechanism effectively overcomes the lag of the traditional feedback control method, enabling the system to respond more quickly to changes in the unit operating conditions. At the same time, through precise feedforward control, the fluctuation of nitrogen oxide concentration is reduced, thereby ensuring the stability of nitrogen oxide emission concentration and saving urea costs.

[0065] S2: Based on the set value of the nitrogen oxide concentration at the outlet of the waste heat boiler and the actual nitrogen oxide concentration, the feedback control amount is calculated through the PID controller.

[0066] Furthermore, the nitrogen oxide concentration set value NOxSP and the actually measured nitrogen oxide concentration NOx are calculated through a PID controller to obtain a feedback control amount MV0.

[0067] S3: The feedforward control amount and the PID feedback control amount are summed to obtain the feedforward-feedback control amount, and then the feedforward-feedback control amount is corrected by the SCR spray gun input rate correction function to obtain the final urea solution flow control valve instruction.

[0068] Furthermore, the final urea solution flow control valve instruction includes summing the feedforward control amount and the PID feedback control amount to obtain the feedforward-feedback control amount, and then taking the ratio of the number of SCR spray guns NU put into use to the total number of SCR spray guns NA as the SCR spray gun investment rate R, referring to Figure 6 , the SCR spray gun input rate R is obtained by the correction function FX3 to obtain the control valve command correction coefficient KMV, and the calculated feedforward-feedback control quantity MV' is corrected by the control valve command correction coefficient KMV, which is expressed as:

[0069] MV′=MV0+FFGT+FFEXF

[0070]

[0071] KMV=FX3(R)

[0072] MV=KMV×MV′

[0073] MV is used as the urea solution flow control valve instruction to control the opening of the urea solution flow control valve. The urea solution flow control valves of different SCR spray guns all use MV as the valve instruction to maintain the same opening.

[0074] It should be noted that the reference Figure 7 , the final urea solution flow control valve instruction also includes when the unit is not configured with the engine exhaust flow calculation logic or the calculated engine exhaust flow is significantly deviated from the normal value, the engine exhaust flow is replaced by the IGV opening, and the engine exhaust flow is significantly deviated from the normal value as:

[0075] EXF≤0 or EXF>KF×EXF0

[0076] Among them, EXF0 is the design value of the exhaust flow of the gas turbine, which is provided by the gas turbine manufacturer. KF is the coefficient for judging whether the exhaust flow of the gas turbine deviates from the normal value, KF=2; IGV represents the IGV opening, FFIGV0 represents the IGV feedforward control amount before the compressor inlet air temperature is corrected, KIGV represents the correction coefficient of the IGV feedforward control amount, FFIGV represents the IGV feedforward control amount, and the feedforward control amount FFIGV0 before the compressor inlet air temperature is corrected is calculated by the IGV opening through the feedforward function FX5. The correction coefficient KIGV of the IGV feedforward control amount is calculated by the compressor inlet air temperature T1 through the correction function FX6. KIGV is used to correct FFIGV0 to obtain the IGV feedforward control amount FFIGV, which is expressed as:

[0077] FFIGV0=FX5(IGV)

[0078] KIGV=FX6(T1)

[0079] FFIGV=KIGV×FFIGV0

[0080] The final urea solution flow control valve command MV is expressed as:

[0081] MV′=MV0+FFGT+FFIGV

[0082] MV=KMV×MV′

[0083] The calculated MV is used to control the opening of the urea solution flow regulating valve and control the nitrogen oxide concentration at the waste heat boiler outlet.

[0084] It should also be noted that after the feedforward control quantities FFGT and FFEXF (or FFIGV) are summed with the traditional PID feedback control quantity MV0, the control valve instruction correction coefficient KMV is obtained through the SCR spray gun input rate correction function FX3, and finally the urea solution flow control valve instruction MV is calculated. This process combines the advantages of feedforward control and feedback control to achieve precise control of the denitrification system; in addition, by introducing the correction of the SCR spray gun input rate, it is ensured that in the multi-spray gun system, the urea injection amount is more reasonable, avoiding the problem of over-injection or under-injection caused by the spray gun input rate, ensuring that the emission concentration of nitrogen oxides is always controlled within the set range, while maximizing the savings of urea resources and improving the economy and environmental benefits of the system.

[0085] Example 2, an embodiment of the present invention, provides a method for controlling a denitration system of a gas-steam combined cycle unit. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through economic benefit calculation and simulation experiments.

[0086] An SCR denitration system is configured on a gas-steam combined cycle simulation unit. Before the experiment, the operating parameters of the denitration system control process of the gas-steam combined cycle unit are first obtained. These parameters include the gas turbine exhaust flow rate (EXF), the compressor inlet air temperature (T1), the gas turbine load (PGT), the set value of the nitrogen oxide concentration at the waste heat boiler outlet (NOxSP), the actually measured nitrogen oxide concentration at the waste heat boiler outlet (NOx), the number of SCR spray guns (NU and NA), etc. The load correction coefficient KGT is calculated according to the actual compressor inlet air temperature T1 through the correction function FX1. Then, the load PGT of the gas turbine is corrected by the correction coefficient to obtain the corrected load PGT'. This correction process eliminates the influence of ambient temperature on the gas turbine load, which is convenient for more accurate description of the feedforward relationship between the gas turbine load and the denitration system. Based on the corrected gas turbine load PGT', the feedforward Function FX2 calculates the load feedforward control quantity FFGT, and the exhaust flow feedforward control quantity FFEXF is calculated through the feedforward function FX4. These feedforward control quantities adjust the urea solution flow in advance before the unit operating conditions change and before causing the change of the nitrogen oxide concentration at the waste heat boiler outlet; at the same time, the nitrogen oxide concentration set value NOxSP and the actually measured nitrogen oxide concentration NOx are calculated by the PID controller. The feedback control quantity MV0; the feedforward control quantities FFGT and FFEXF are summed with the traditional PID feedback control quantity MV0 to obtain the feedforward-feedback control quantity, and then the SCR gun input rate is calculated by the correction function FX3. The control valve instruction correction coefficient KMV, finally, the feedforward-feedback control quantity is corrected by KMV to obtain the final urea solution flow control valve instruction MV, which is used to control the injection amount of urea solution in the SCR system to ensure that the nitrogen oxide emission concentration remains within the set range.

[0087] Compared with the traditional single PID control method, the feedforward-feedback control strategy of the present invention not only improves the response speed of the system, but also reduces resource waste, thereby improving the economy and environmental benefits of the denitrification system.

[0088] Example 3, reference Fig.10 , which is an embodiment of the present invention, provides a control system for a denitration system of a gas-steam combined cycle unit, including a data acquisition module, a feedforward control quantity calculation module, a feedback control quantity calculation module, and a control quantity correction module.

[0089] The data acquisition module is used to obtain the operating parameters required for the control process of the denitrification system of the gas-steam combined cycle unit; the feedforward control quantity calculation module is used to correct the gas turbine load using the compressor inlet air temperature, and calculate the load feedforward control quantity and the exhaust flow feedforward control quantity through the feedforward function based on the corrected gas turbine load and the gas turbine exhaust flow; the feedback control quantity calculation module is used to calculate the feedback control quantity through the PID controller based on the set value of the nitrogen oxide concentration at the outlet of the waste heat boiler and the actual nitrogen oxide concentration; the control quantity correction module is used to sum the feedforward control quantity and the PID feedback control quantity to obtain the feedforward-feedback control quantity, and then correct the feedforward-feedback control quantity through the SCR gun input rate correction function to obtain the final urea solution flow regulating valve instruction.

[0090] If the function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the methods of each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc. Various media that can store program codes.

[0091] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in conjunction with such instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in conjunction with such instruction execution systems, devices or apparatuses.

[0092] More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic device), a portable computer disk case (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be a paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, deciphering, or processing in another suitable manner as necessary, and then stored in a computer memory.

[0093] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc. It should be noted that the above embodiments are only used to illustrate the technical solution of the present invention and are not limited. Although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

[0094] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for controlling a denitration system of a gas-steam combined cycle unit, characterized in that: include: The operating parameters of the denitration system control process of the gas-steam combined cycle unit are obtained, the load of the gas turbine is corrected by using the compressor inlet air temperature, and based on the corrected gas turbine load and gas turbine exhaust flow, the load feedforward control amount and the exhaust flow feedforward control amount are calculated by the feedforward function; Based on the set value of the nitrogen oxide concentration at the outlet of the waste heat boiler and the actual nitrogen oxide concentration, the feedback control amount is calculated by the PID controller; The feedforward control quantity and the PID feedback control quantity are summed to obtain the feedforward-feedback control quantity, and then the feedforward-feedback control quantity is corrected by the SCR spray gun input rate correction function to obtain the final urea solution flow control valve instruction.

2. The method for controlling a denitration system of a gas-steam combined cycle unit according to claim 1, characterized in that: The operating parameters include the gas turbine exhaust flow EXF, the compressor inlet air temperature T1, the gas turbine load PGT, the set value NOxSP of the nitrogen oxide concentration at the waste heat boiler outlet, the actually measured nitrogen oxide concentration NOx at the waste heat boiler outlet, the number of SCR spray guns NU put into use, the total number NA of SCR spray guns, the urea solution flow control valve instruction MV0 calculated by PID feedback control, the load correction coefficient KGT, the gas turbine load PGT' after the compressor inlet air temperature is corrected, the load feedforward control amount FFGT, the exhaust flow feedforward control amount FFEXF, the SCR spray gun input rate R, the control valve instruction correction coefficient KMV, the feedforward-feedback control amount MV', and the final urea solution flow control valve instruction MV.

3. The method for controlling a denitration system of a gas-steam combined cycle unit according to claim 2, characterized in that: The method of correcting the engine load by using the compressor inlet air temperature includes calculating the load correction coefficient KGT by the compressor inlet air temperature T1 through the correction function FX1, and correcting the engine load PGT, which is expressed as: KGT=FX1(T1) PGT'=KGT×PGT Among them, PGT' is the corrected gas turbine load.

4. The method for controlling a denitration system of a gas-steam combined cycle unit according to claim 3, characterized in that: The calculation of the load feedforward control quantity and the exhaust flow feedforward control quantity by the feedforward function includes calculating the load feedforward control quantity FFGT by the feedforward function FX2 after the modified engine load PGT', which is expressed as: FFGT=FX2(PGT′) The exhaust flow rate EXF of the combustion engine is calculated by the feedforward function FX4 to calculate the exhaust flow rate feedforward control amount FFEXF, which is expressed as: FFEXF=FX4(EXF) The function curves of the correction function and the feedforward function are determined by the unit characteristics and on-site debugging.

5. The method for controlling a denitration system of a gas-steam combined cycle unit according to claim 4, characterized in that: The nitrogen oxide concentration set value NOxSP and the actually measured nitrogen oxide concentration NOx are calculated through a PID controller to calculate the feedback control amount MV0.

6. The method for controlling a denitration system of a gas-steam combined cycle unit according to claim 5, characterized in that: The method of obtaining the final urea solution flow control valve instruction includes summing the feedforward control amount and the PID feedback control amount to obtain the feedforward-feedback control amount, and then taking the ratio of the number of SCR spray guns NU put into use to the total number of SCR spray guns NA as the SCR spray gun investment rate R, and obtaining the control valve instruction correction coefficient KMV by the correction function FX3 of the SCR spray gun investment rate R, and correcting the calculated feedforward-feedback control amount MV' by using the control valve instruction correction coefficient KMV, which is expressed as: MV′=MV0+FFGT+FFEXF KMV=FX3(R) MV=KMV×MV′ MV is used as the urea solution flow control valve instruction to control the opening of the urea solution flow control valve. The urea solution flow control valves of different SCR spray guns all use MV as the valve instruction to maintain the same opening.

7. The method for controlling a denitration system of a gas-steam combined cycle unit according to claim 6, characterized in that: The method of obtaining the final urea solution flow control valve instruction also includes replacing the engine exhaust flow with the IGV opening when the unit is not configured with the engine exhaust flow calculation logic or the calculated engine exhaust flow obviously deviates from the normal value. The engine exhaust flow obviously deviates from the normal value as: EXF≤0 or EXF>KF×EXF0 Among them, EXF0 is the design value of the exhaust flow rate of the gas turbine, which is provided by the gas turbine manufacturer, and KF is the coefficient for judging the deviation of the exhaust flow rate of the gas turbine from the normal value, KF = 2; IGV represents the IGV opening, FFIGV0 represents the IGV feedforward control amount before the compressor inlet air temperature is corrected, KIGV represents the correction coefficient of the IGV feedforward control amount, FFIGV represents the IGV feedforward control amount, the feedforward control amount FFIGV0 before the compressor inlet air temperature is corrected is calculated by the IGV opening through the feedforward function FX5, the correction coefficient KIGV of the IGV feedforward control amount is calculated by the compressor inlet air temperature T1 through the correction function FX6, and FFIGV0 is corrected by KIGV to obtain the IGV feedforward control amount FFIGV, which is expressed as: FFIGV0=FX5(IGV) KIGV=FX6(T1) FFIGV=KIGV×FFIGV0 The final urea solution flow control valve command MV is expressed as: MV′=MV0+FFGT+FFIGV MV=KMV×MV′ The calculated MV is used to control the opening of the urea solution flow regulating valve and control the nitrogen oxide concentration at the waste heat boiler outlet.

8. A system using the gas-steam combined cycle unit denitration system control method according to any one of claims 1 to 7, characterized in that: It includes a data acquisition module, a feedforward control quantity calculation module, a feedback control quantity calculation module, and a control quantity correction module; The data acquisition module is used to obtain the operating parameters required for the control process of the denitration system of the gas-steam combined cycle unit; The feedforward control quantity calculation module is used to correct the engine load by using the compressor inlet air temperature, and calculate the load feedforward control quantity and the exhaust flow feedforward control quantity through a feedforward function based on the corrected engine load and the engine exhaust flow; The feedback control amount calculation module is used to calculate the feedback control amount through a PID controller based on the set value of the nitrogen oxide concentration at the outlet of the waste heat boiler and the actual nitrogen oxide concentration; The control amount correction module is used to sum the feedforward control amount and the PID feedback control amount to obtain the feedforward-feedback control amount, and then correct the feedforward-feedback control amount through the SCR spray gun input rate correction function to obtain the final urea solution flow control valve instruction.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the gas-steam combined cycle unit denitration system control method described in any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method for controlling a denitration system of a gas-steam combined cycle unit according to any one of claims 1 to 7 are implemented.

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