Fast frequency modulation supercritical unit water supply optimization control method and system

Abstract

The invention provides a fast frequency modulation supercritical unit water supply optimization control method and system, and belongs to the technical field of coal power unit water supply automatic control. The method comprises the steps that a boiler master control instruction obtains the steady-state feed water flow according to the coal-water ratio, and the steady-state feed water flow is obtained through an enthalpy value regulator according to the set temperature of a separator and the temperature of an outlet of the separator; a water supply instruction is generated through the water supply adjustment PID control block; performing conversion function processing on the water supply instruction, performing effective differential pressure guarantee adjustment, judging whether to perform amplitude limiting, performing amplitude limiting when the real-time differential pressure is smaller than a guarantee value, and not performing amplitude limiting when the real-time differential pressure is greater than or equal to the guarantee value; a small machine output instruction is output to control the opening degree of a small machine control valve and the rotating speed of a water pump after effective pressure difference guarantee adjustment, and the water supply flow is controlled. The method accurately identifies the frequency modulation load reduction working condition, avoids the instability of water circulation, optimizes the automatic control logic of water supply, and guarantees the timely and rapid load response of the unit.

Description

Technical Field

[0001] The invention relates to a method and system for optimizing water supply control of a fast frequency modulation supercritical unit, belonging to the technical field of automatic water supply control of coal-fired power units. Background Art

[0002] With the rapid development of new power systems and the rapid growth of new energy grid-connected capacity, the demand for frequency regulation of power systems is increasing. The random volatility of wind power and photovoltaic power generation has caused the task of grid frequency regulation to become more frequent and complex. In this context, large-capacity supercritical coal-fired power units have gradually become the main force in power system frequency regulation. Taking Shandong Power Grid as an example, 20 to 30 coal-fired power units are required to participate in frequency regulation operations every day. In the process of supercritical coal-fired power units participating in frequency regulation operation, frequent load regulation has become the norm, which directly leads to the need for rapid response regulation of water supply flow.

[0003] The existing automatic control scheme for supercritical unit feedwater mainly adopts the cascade automatic control scheme of coal-water ratio and intermediate point temperature. Under this control strategy, the feedwater flow rate corresponds to the unit load one by one, and the steam intake of the small steam turbine is controlled only according to the feedwater flow rate to adjust the output of the small steam turbine. Such a control system requires that the feedwater flow signal must be steady and accurate. If the feedwater flow signal is dynamically unstable under fast load change conditions such as load reduction and frequency modulation, the automatic adjustment system may form an incorrect adjustment, which brings a series of technical challenges: Due to the lack of sufficient volume space, the rapid closure of the regulating valve during the load reduction and frequency regulation process will cause the resistance of the water supply pipeline system to rise sharply, thereby increasing the water supply power demand. The control system reduces the water supply flow rate according to the load command and reduces the output of the small unit accordingly, which further causes the pressure difference of the water supply system to drop, making it difficult to fill the boiler with water. The water supply flow rate may drop to zero quickly, and the stability of the water cycle will be destroyed. The instability of the water cycle will lead to the following consequences: (1) The water supply recirculation will start incorrectly, the water supply flow rate and water supply pressure will drop, and the stability of the water cycle will be further destroyed. (2) After the water supply flow rate drops rapidly and deviates from the target value, the small unit needs to increase its output quickly to restore the flow rate, but this rapid response often leads to flow overregulation. Subsequently, the small unit reduces its output again, and the flow rate will drop sharply again, forming an oscillation amplification phenomenon of flow regulation. (3) If this oscillation trend continues, it may eventually cause the automatic regulation system to exit, or even trigger the low water supply flow protection, causing the unit to trip, seriously affecting the safe and stable operation of the power system.

[0004] Therefore, developing an automatic water supply control technology for supercritical coal-fired power units that can effectively meet the above challenges is of great significance for ensuring the safe operation of supercritical units and the stable operation of new power systems. Summary of the invention

[0005] The purpose of the present invention is to provide a method and system for optimizing the water supply control of a fast frequency modulation supercritical unit, and to optimize the water supply automatic control logic.

[0006] In order to achieve the above object, the present invention is implemented through the following technical solutions: A method for optimizing feedwater control of a fast frequency modulation supercritical unit comprises the following steps: The boiler master control command obtains the steady-state feedwater flow rate according to the coal-water ratio, and the separator set temperature and the separator outlet temperature are used by the enthalpy regulator to obtain the steady-state feedwater flow rate; The steady-state water supply flow rate and the sum of the steady-state water supply flow rate minus the current water supply flow rate generate a water supply instruction through a water supply regulation PID control block; The water supply instruction is processed by the conversion function to adjust the effective pressure difference and determine whether to limit the pressure. When the real-time differential pressure is less than the guaranteed value, the pressure is limited. When the real-time differential pressure is greater than or equal to the guaranteed value, the pressure is not limited. The effective pressure difference is used to ensure that the output command of the small machine is output after adjustment to control the opening of the small machine valve and the speed of the water pump, thereby controlling the water supply flow.

[0007] Preferably, the water supply regulation PID control block includes a conventional water supply regulation PID control block and a frequency modulation and load reduction water supply regulation PID control block. The proportional coefficient of the frequency modulation and load reduction water supply regulation PID control block is reduced to 5% of that of the conventional water supply regulation PID control block, and the integral time constant becomes 30 times that of the conventional water supply regulation PID control block.

[0008] Preferably, the specific method of generating the water supply instruction by the water supply regulation PID control block is as follows: The frequency modulation and load reduction condition is identified by parsing the frequency modulation instruction. If it is not a frequency modulation and load reduction condition, the water supply instruction is generated by the conventional water supply regulation PID control block. If it is a frequency modulation and load reduction condition, the water supply instruction is generated by the frequency modulation and load reduction water supply regulation PID control block.

[0009] Preferably, the specific method of identifying the frequency modulation and load reduction working condition by parsing the frequency modulation instruction is as follows: When a frequency regulation and load reduction command is issued and the load reduction exceeds 1.5% of the rated power, or the unit receives a load reduction command while operating in AGCR mode and the load reduction exceeds 2% of the rated power, it is judged as a frequency regulation and load reduction condition.

[0010] Preferably, the effective pressure difference is ensured and adjusted in a specific manner as follows: Monitor the difference between the economizer inlet pressure and the main steam pressure in real time, and compare the monitored real-time differential pressure with the guaranteed value; if the real-time differential pressure is less than the guaranteed value, the limiting link is activated, and all instructions to reduce the output of small machines are output as 0, while instructions to increase the output remain unchanged; if the real-time differential pressure is greater than or equal to the guaranteed value, the limiting link is exited and the original value is output.

[0011] Preferably, the guaranteed value is 60% of the design differential pressure.

[0012] A fast frequency regulation supercritical unit feed water optimization control system, comprising: Feedwater flow calculation module: It is configured as the boiler master control instruction to obtain the steady-state feedwater flow according to the coal-water ratio, and the separator setting temperature and the separator outlet temperature are used to obtain the steady-state feedwater flow through the enthalpy regulator; A water supply instruction generation module: configured to generate a water supply instruction by subtracting the current water supply flow from the sum of the steady-state water supply flow through a water supply regulation PID control block; Effective pressure difference guarantee module: It is configured to process the water supply instruction through the conversion function, perform effective pressure difference guarantee adjustment, and judge whether to limit the amplitude. When the real-time differential pressure is less than the guaranteed value, the amplitude is limited. When the real-time differential pressure is greater than or equal to the guaranteed value, the amplitude is not limited. Water supply flow adjustment module: It is configured to output the small machine output command to control the opening of the small machine regulating valve and the speed of the water pump after adjustment through the effective pressure difference to control the water supply flow.

[0013] Preferably, the system also includes a frequency modulation and load reduction determination module, which identifies the frequency modulation and load reduction condition by parsing the frequency modulation instruction, and the determination method is as follows: a frequency modulation and load reduction instruction is issued once and the load reduction range exceeds 1.5% of the rated power or the unit operates in AGC R mode and receives a load reduction instruction and the load reduction range exceeds 2% of the rated power; after determining that it is a frequency modulation and load reduction condition, the module output is set to 1, and in other cases it is set to 0.

[0014] Preferably, the effective pressure difference guarantee module includes a differential pressure real-time monitoring sub-function block, a guaranteed value comparison sub-function block, and a limiting link sub-function block; The differential pressure real-time monitoring sub-function block monitors the difference between the economizer inlet pressure and the main steam pressure in real time; The guaranteed value comparison sub-function block compares the monitored real-time differential pressure with the guaranteed value; The limiting link sub-function block determines whether the limiting link is put into operation based on the size of the real-time differential pressure and the guaranteed value of the implemented differential pressure; specifically: if the real-time differential pressure is less than the guaranteed value, the limiting link is put into operation, all instructions for reducing the output of the small machine are output as 0, and the instructions for increasing the output remain unchanged; if the real-time differential pressure is greater than or equal to the guaranteed value, the limiting link is exited, and the function block outputs the original value with a proportional coefficient of 1.

[0015] A fast frequency modulation supercritical unit feed water optimization control device comprises a processor and a memory storing program instructions, wherein the processor is configured to execute the fast frequency modulation supercritical unit feed water optimization control method when running the program instructions.

[0016] The advantages of the present invention are: accurately identifying the dangerous working condition of frequency modulation and load reduction. When the unit is in the frequency modulation and load reduction condition, by weakening the adjustment amplitude of the regulator, the adjustment amplitude of the feedwater pump turbine output is greatly reduced, the output fluctuation of the feedwater pump is reduced, and the instability of the water cycle is avoided.

[0017] The water supply automatic control logic is optimized. Flow rate is no longer used as the only signal for small machine output adjustment. The water supply pressure difference is introduced as an auxiliary criterion. When the water supply differential pressure is large enough, the water pump output is adjusted up or down as needed. When the water supply differential pressure cannot meet the requirements of stable water circulation, the pressure requirements are met first, and the small machine output reduction adjustment is locked to ensure the stability of the water circulation.

[0018] Outside of dangerous operating conditions, the original system adjustment accuracy and handover speed are still maintained to ensure that the unit load response is timely and rapid. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention.

[0020] Figure 1 It is a schematic diagram of the process of the present invention.

[0021] Figure 2 This is a schematic diagram of the optimized automatic water supply control system of the present invention.

[0022] Figure 3 This is a schematic diagram of the existing water supply automatic control system.

[0023] In the figure: Σ is the summing link; PID refers to the proportional integral differential controller, and the subscripts are used to distinguish different pre-control parameters; the limiting link outputs negative values ​​as 0 and positive values ​​as the original value; - represents the difference operation. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] Example 1 like Figure 1 As shown, a method for optimizing feedwater control of a fast frequency modulation supercritical unit comprises the following steps: S1: The boiler master control command obtains the steady-state feedwater flow rate according to the coal-water ratio, and the separator set temperature and the separator outlet temperature are used by the enthalpy regulator to obtain the steady-state feedwater flow rate; S2: The steady-state water supply flow rate, the sum of the steady-state water supply flow rate minus the current water supply flow rate, is used to generate a water supply instruction through a water supply regulation PID control block; S3: The water supply instruction is processed by the conversion function, and the effective pressure difference is guaranteed and adjusted to determine whether to limit the amplitude. When the real-time differential pressure is less than the guaranteed value, the amplitude is limited. When the real-time differential pressure is greater than or equal to the guaranteed value, the amplitude is not limited. S4: After adjustment, the output command of the small machine is output to control the opening of the small machine valve and the speed of the water pump through the effective pressure difference to control the water supply flow.

[0026] As a refinement of the above embodiment, the water supply regulation PID control block includes a conventional water supply regulation PID control block and a frequency modulation and load reduction water supply regulation PID control block. The proportional coefficient of the frequency modulation and load reduction water supply regulation PID control block is reduced to 5% of that of the conventional water supply regulation PID control block, and the integral time constant becomes 30 times that of the conventional water supply regulation PID control block.

[0027] As a refinement of the above embodiment, the specific method of generating the water supply instruction by the water supply regulation PID control block is as follows: The frequency modulation and load reduction condition is identified by parsing the frequency modulation instruction. If it is not a frequency modulation and load reduction condition, the water supply instruction is generated by the conventional water supply regulation PID control block. If it is a frequency modulation and load reduction condition, the water supply instruction is generated by the frequency modulation and load reduction water supply regulation PID control block.

[0028] As a refinement of the above embodiment, the specific method of identifying the frequency regulation and load reduction condition by parsing the frequency regulation instruction is as follows: When a frequency regulation and load reduction command is issued and the load reduction exceeds 1.5% of the rated power, or the unit receives a load reduction command while operating in AGCR mode and the load reduction exceeds 2% of the rated power, it is judged as a frequency regulation and load reduction condition.

[0029] As a refinement of the above embodiment, the specific method of regulating the effective pressure difference guarantee is as follows: Monitor the difference between the economizer inlet pressure and the main steam pressure in real time, and compare the monitored real-time differential pressure with the guaranteed value; if the real-time differential pressure is less than the guaranteed value, the limiting link is activated, and all instructions to reduce the output of small machines are output as 0, while instructions to increase the output remain unchanged; if the real-time differential pressure is greater than or equal to the guaranteed value, the limiting link is exited and the original value is output.

[0030] As a refinement of the above embodiment, the guaranteed value is 60% of the design differential pressure.

[0031] Example 2 like Figure 2 A fast frequency regulation supercritical unit feed water optimization control system is shown, comprising: Feedwater flow calculation module: It is configured as the boiler master control instruction to obtain the steady-state feedwater flow according to the coal-water ratio, and the separator setting temperature and the separator outlet temperature are used to obtain the steady-state feedwater flow through the enthalpy regulator; A water supply instruction generation module: configured to generate a water supply instruction by subtracting the current water supply flow from the sum of the steady-state water supply flow through a water supply regulation PID control block; Effective pressure difference guarantee module: It is configured to process the water supply instruction through the conversion function, perform effective pressure difference guarantee adjustment, and judge whether to limit the amplitude. When the real-time differential pressure is less than the guaranteed value, the amplitude is limited. When the real-time differential pressure is greater than or equal to the guaranteed value, the amplitude is not limited. Water supply flow adjustment module: It is configured to output the small machine output command to control the opening of the small machine regulating valve and the speed of the water pump after adjustment through the effective pressure difference to control the water supply flow.

[0032] As a refinement of the above embodiment, the system also includes a frequency regulation and load reduction judgment module, which identifies the frequency regulation and load reduction condition by parsing the frequency regulation instruction, and the judgment method is as follows: a frequency regulation and load reduction instruction is received and the load reduction range exceeds 1.5% of the rated power or the unit operates in AGC R mode and receives a load reduction instruction and the load reduction range exceeds 2% of the rated power; after determining that it is a frequency regulation and load reduction condition, the module output is set to 1, and in other cases it is set to 0.

[0033] The PID control block for the unit feed water regulation under frequency modulation and load reduction conditions is as follows: Figure 2 As shown in PIDn, the adjustment range of PIDn control block is significantly smaller than PID2, where the proportional coefficient is reduced to 5% of PID2, and the integral time constant becomes 30 times of PID2. After PIDn is put into operation, the change range of water supply instruction will be greatly reduced.

[0034] After the frequency modulation and load reduction judgment module is set to 1, the water supply regulation PID control block switches to PIDn. The frequency modulation and load reduction judgment modules for other working conditions are set to 0, and the water supply regulation PID control block maintains PID2.

[0035] As a refinement of the above embodiment, the effective pressure difference guarantee module includes a differential pressure real-time monitoring sub-function block, a guaranteed value comparison sub-function block, and a limiting link sub-function block; The differential pressure real-time monitoring sub-function block monitors the difference between the economizer inlet pressure and the main steam pressure in real time; The guaranteed value comparison sub-function block compares the monitored real-time differential pressure with the guaranteed value; The limit link sub-function block determines whether the limit link is put into operation according to the difference between the real-time differential pressure and the guaranteed value; specifically, if the real-time differential pressure is lower than the guaranteed value, the limit link is put into operation, and all instructions for reducing the output of the small machine are output as 0, and the instructions for increasing the output remain unchanged, so as to achieve the purpose of locking the small machine to reduce the output. If the real-time differential pressure is higher than the guaranteed value, the limit link is exited, and the function block outputs the original value with a proportional coefficient of 1, which does not affect the execution of the original function.

[0036] Working principle: The present invention proposes a method and system for optimizing the control of feedwater for a fast frequency-modulated supercritical unit. First, by introducing the effective differential pressure judgment function of the boiler feedwater, when the boiler differential pressure is insufficient and it is difficult to supply water, the small unit is locked to adjust the direction of output reduction, ensuring that the small unit can overcome the contradiction between power reduction and increased feedwater pressure loss, giving priority to ensuring the safety of the feedwater cycle. Secondly, by accurately judging the frequency-modulated output reduction working conditions and setting a stable proportional-integral regulator, the output fluctuation of the small steam turbine of the unit under adverse working conditions such as frequency-modulated output reduction is reduced, avoiding large fluctuations in the unit's feedwater, which may lead to the start of feedwater recirculation or even machine tripping.

[0037] The embodiment of the present disclosure provides a fast frequency modulation supercritical unit feedwater optimization control device, including a processor and a memory. Optionally, the device may also include a communication interface and a bus. The processor, the communication interface, and the memory may communicate with each other through the bus. The communication interface may be used for information transmission. The processor may call the logic instructions in the memory to execute the fast frequency modulation supercritical unit feedwater optimization control method of the above embodiment.

[0038] In addition, the logic instructions in the above-mentioned memory can be implemented in the form of software functional units and can be stored in a computer-readable storage medium when sold or used as an independent product.

[0039] The technical solution of the embodiment of the present disclosure can be embodied in the form of a software product, which is stored in a storage medium and includes one or more instructions for enabling a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in the embodiment of the present disclosure. The aforementioned storage medium may be a non-transient storage medium, including: a USB flash drive, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a disk or an optical disk, and other media that can store program codes, or a transient storage medium.

[0040] The above description and the accompanying drawings fully illustrate the embodiments of the present disclosure so that those skilled in the art can practice them. Other embodiments may include structural, logical, electrical, process and other changes. The embodiments represent only possible changes. Unless explicitly required, separate components and functions are optional, and the order of operations may vary. Parts and features of some embodiments may be included in or replace parts and features of other embodiments. Moreover, the words used in this application are only used to describe the embodiments and are not used to limit the claims. As used in the description of the embodiments and the claims, unless the context clearly indicates, the singular forms of "a", "an" and "the" are intended to include plural forms as well. Similarly, the term "and / or" as used in this application refers to any and all possible combinations of one or more associated listings. In addition, when used in this application, the term "comprise" and its variants "comprises" and / or comprising refer to the presence of stated features, wholes, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or groups thereof. In the absence of further restrictions, the elements defined by the sentence "including one..." do not exclude the presence of other identical elements in the process, method or device including the elements. In this article, each embodiment may focus on the differences from other embodiments, and the same and similar parts between the embodiments may refer to each other. For the methods, products, etc. disclosed in the embodiments, if they correspond to the method part disclosed in the embodiments, then the relevant parts can refer to the description of the method part.

[0041] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software may depend on the specific application and design constraints of the technical solution. The technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the embodiments of the present disclosure. The technicians may clearly understand that for the convenience and simplicity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments, and will not be repeated here.

[0042] In the embodiments disclosed herein, the disclosed methods and products (including but not limited to devices, equipment, etc.) can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units can be only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between each other shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms. The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the units may be selected according to actual needs to implement this embodiment. In addition, each functional unit in the embodiment of the present disclosure may be integrated in a processing unit, or each unit may exist physically separately, or two or more units may be integrated in one unit.

[0043] The flowchart and block diagram in the accompanying drawings show the possible architecture, function and operation of the system, method and computer program product according to the embodiment of the present disclosure. In this regard, each box in the flowchart or block diagram can represent a module, a program segment or a part of the code, and the module, the program segment or a part of the code contains one or more executable instructions for realizing the specified logical function. In some alternative implementations, the functions marked in the box can also occur in a different order from the order marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, which can depend on the functions involved. In the description corresponding to the flowchart and the block diagram in the accompanying drawings, the operations or steps corresponding to different boxes can also occur in a different order from the order disclosed in the description, and sometimes there is no specific order between different operations or steps. For example, two consecutive operations or steps can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, which can depend on the functions involved. Each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, may be implemented by a dedicated hardware-based system that performs the specified functions or actions, or may be implemented by a combination of dedicated hardware and computer instructions.

Claims

1. A method for optimizing feedwater control of a fast frequency modulation supercritical unit, characterized in that: The following steps are involved: The boiler master control command obtains the steady-state feedwater flow rate according to the coal-water ratio, and the separator set temperature and the separator outlet temperature are used by the enthalpy regulator to obtain the steady-state feedwater flow rate; The steady-state water supply flow rate and the sum of the steady-state water supply flow rate minus the current water supply flow rate generate a water supply instruction through a water supply regulation PID control block; The water supply instruction is processed by the conversion function to adjust the effective pressure difference and determine whether to limit the pressure. When the real-time differential pressure is less than the guaranteed value, the pressure is limited. When the real-time differential pressure is greater than or equal to the guaranteed value, the pressure is not limited. The effective pressure difference is used to ensure that the output command of the small machine is output after adjustment to control the opening of the small machine valve and the speed of the water pump, thereby controlling the water supply flow.

2. The method for optimizing water supply control of a fast frequency modulation supercritical unit according to claim 1, characterized in that: The water supply regulation PID control block includes a conventional water supply regulation PID control block and a frequency modulation and load reduction water supply regulation PID control block. The proportional coefficient of the frequency modulation and load reduction water supply regulation PID control block is reduced to 5% of that of the conventional water supply regulation PID control block, and the integral time constant becomes 30 times that of the conventional water supply regulation PID control block.

3. The method for optimizing water supply control of a fast frequency modulation supercritical unit according to claim 2, characterized in that: The specific method of generating the water supply instruction through the water supply regulation PID control block is as follows: The frequency modulation and load reduction condition is identified by parsing the frequency modulation instruction. If it is not a frequency modulation and load reduction condition, the water supply instruction is generated by the conventional water supply regulation PID control block. If it is a frequency modulation and load reduction condition, the water supply instruction is generated by the frequency modulation and load reduction water supply regulation PID control block.

4. The method for optimizing water supply control of a fast frequency modulation supercritical unit according to claim 3 is characterized in that: The specific method of identifying the frequency modulation and load reduction condition by parsing the frequency modulation instruction is as follows: When a frequency regulation and load reduction command is issued and the load reduction exceeds 1.5% of the rated power, or the unit receives a load reduction command while operating in AGC-R mode and the load reduction exceeds 2% of the rated power, it is judged as a frequency regulation and load reduction condition.

5. The method for optimizing water supply control of a fast frequency modulation supercritical unit according to claim 1, characterized in that: The specific method of ensuring the effective pressure difference adjustment is as follows: Monitor the difference between the economizer inlet pressure and the main steam pressure in real time, and compare the monitored real-time differential pressure with the guaranteed value; if the real-time differential pressure is less than the guaranteed value, the limiting link is activated, and all instructions to reduce the output of small machines are output as 0, while instructions to increase the output remain unchanged; if the real-time differential pressure is greater than or equal to the guaranteed value, the limiting link is exited and the original value is output.

6. The method for optimizing water supply control of a fast frequency modulation supercritical unit according to any one of claims 1 to 5, characterized in that: The guaranteed value is 60% of the design differential pressure.

7. A fast frequency modulation supercritical unit feedwater optimization control system using the method described in any one of claims 1 to 6, characterized in that: include: Feedwater flow calculation module: It is configured as the boiler master control instruction to obtain the steady-state feedwater flow according to the coal-water ratio, and the separator setting temperature and the separator outlet temperature are used to obtain the steady-state feedwater flow through the enthalpy regulator; A water supply instruction generation module: configured to generate a water supply instruction by subtracting the current water supply flow from the sum of the steady-state water supply flow through a water supply regulation PID control block; Effective pressure difference guarantee module: It is configured to process the water supply instruction through the conversion function, perform effective pressure difference guarantee adjustment, and judge whether to limit the amplitude. When the real-time differential pressure is less than the guaranteed value, the amplitude is limited. When the real-time differential pressure is greater than or equal to the guaranteed value, the amplitude is not limited. Water supply flow adjustment module: It is configured to output the small machine output command to control the opening of the small machine regulating valve and the speed of the water pump after adjustment through the effective pressure difference to control the water supply flow.

8. The water supply optimization control system for a fast frequency modulation supercritical unit according to claim 7 is characterized in that: The system also includes a frequency modulation and load reduction judgment module, which identifies the frequency modulation and load reduction condition by parsing the frequency modulation command, and the judgment method is as follows: a frequency modulation and load reduction command is received and the load reduction range exceeds 1.5% of the rated power or the unit operates in AGC-R mode and receives a load reduction command and the load reduction range exceeds 2% of the rated power; after determining that it is a frequency modulation and load reduction condition, the module output is set to 1, and in other cases it is set to 0.

9. The fast frequency modulation supercritical unit feed water optimization control system according to claim 7, characterized in that: The effective pressure difference guarantee module includes a differential pressure real-time monitoring sub-function block, a guaranteed value comparison sub-function block, and a limiting link sub-function block; The differential pressure real-time monitoring sub-function block monitors the difference between the economizer inlet pressure and the main steam pressure in real time; The guaranteed value comparison sub-function block compares the monitored real-time differential pressure with the guaranteed value; The limiting link sub-function block determines whether the limiting link is put into operation based on the size of the real-time differential pressure and the guaranteed value of the implemented differential pressure; specifically: if the real-time differential pressure is less than the guaranteed value, the limiting link is put into operation, all instructions for reducing the output of the small machine are output as 0, and the instructions for increasing the output remain unchanged; if the real-time differential pressure is greater than or equal to the guaranteed value, the limiting link is exited, and the function block outputs the original value with a proportional coefficient of 1.

10. A fast frequency modulation supercritical unit feedwater optimization control device, comprising a processor and a memory storing program instructions, characterized in that: The processor is configured to execute the rapid frequency regulation supercritical unit feed water optimization control method as described in any one of claims 1-6 when running the program instructions.

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