Control method and system for desuperheating water of thermal power plant

Abstract

The application belongs to the technical field of desuperheating water control, and particularly discloses a control method and system for desuperheating water of a thermal power plant, wherein the method comprises the following steps: obtaining a set value and an actual value of steam temperature; when the difference between the set value and the actual value is less than a first threshold value or greater than a second threshold value, coarsely adjusting the opening value of a desuperheating water regulating valve so that the actual value of the steam temperature meets a preset condition; determining the maximum opening limit value and the minimum opening limit value of PID control according to the opening value of the desuperheating water regulating valve when the actual value of the steam temperature meets the preset condition; when the difference between the set value and the actual value is between the first threshold value and the second threshold value, finely adjusting the opening value of the desuperheating water regulating valve by PID control in combination with the maximum opening limit value and the minimum opening limit value. The opening of the desuperheating water regulating valve is controlled in a smaller interval first, and then finely adjusted by PID control, so that the steam temperature can be quickly stabilized and large fluctuation of the steam temperature can be avoided.

Description

Technical Field

[0001] This invention belongs to the field of desuperheating water control technology, and specifically discloses a control method and system for desuperheating water in thermal power plants. Background Technology

[0002] During the operation of thermal power plants, some systems require the introduction of desuperheating water to ensure that relevant system parameters reach expected values, especially the low-pressure cylinder shaft seal steam system. The setpoint for the shaft seal steam temperature in the low-pressure cylinder shaft seal steam system is generally 150℃. Too low a shaft seal steam temperature or drastic temperature fluctuations can affect the vibration of the turbine's low-pressure rotor to varying degrees. Therefore, controlling the low-pressure cylinder shaft seal steam temperature to reach the expected value and maintaining temperature stability or within a small range is crucial for the normal operation of the turbine. Analysis has determined that one reason for the large fluctuations in the low-pressure cylinder shaft seal steam temperature is the frequent over-adjustment in the PID control process of the desuperheating water regulating valve in the low-pressure cylinder shaft seal header. Over-adjustment causes the shaft seal desuperheating water regulating valve to fluctuate significantly, thus causing large fluctuations in the shaft seal steam temperature. Summary of the Invention

[0003] The purpose of this invention is to provide a control method and system for desuperheating water in thermal power plants, so as to solve the technical problem that the existing desuperheating water control method has over-adjustment phenomenon, which leads to large fluctuations in shaft seal steam temperature.

[0004] The first aspect of the present invention provides a method for controlling desuperheating water in a thermal power plant, comprising: Step 1: Obtain the setpoint and actual value of the steam temperature; Step 2: When the difference between the set value and the actual value is less than the first threshold or greater than the second threshold, the opening value of the desuperheating water regulating valve is coarsely adjusted so that the actual value of the steam temperature meets the preset conditions. Step 3: Determine the maximum and minimum opening limits for PID control based on the opening value of the desuperheating water regulating valve when the actual value of the steam temperature meets the preset conditions; Step 4: When the difference between the set value and the actual value is between the first threshold and the second threshold, the opening value of the desuperheating water regulating valve is finely adjusted by combining the maximum opening limit and the minimum opening limit using PID control.

[0005] Preferably, the opening value of the desuperheating water regulating valve is coarsely adjusted so that the actual value of the steam temperature meets the preset conditions, specifically: Obtain the current opening value of the desuperheating water regulating valve, and determine the target opening value based on the current opening value; Within a preset time period, the rate of change of the actual value of steam temperature during the process of adjusting the desuperheating water regulating valve to the target opening value is determined. When the rate of change reaches a first rate of change threshold, the target opening value is updated until the difference between the set value and the actual value meets the requirements. After the difference between the set value and the actual value meets the requirements, the rate of change of the actual value of the steam temperature is determined. If the rate of change is less than the second rate of change threshold, the actual value of the steam temperature is considered to meet the preset conditions.

[0006] Preferably, when the difference between the set value and the actual value is less than a first threshold, the current opening value of the desuperheating water regulating valve is obtained, and a target opening value is determined based on the current opening value, specifically: Obtain the current opening value of the desuperheating water regulating valve; Based on the current opening value of the desuperheating water regulating valve, determine the process opening value and the initial maximum opening value; The target opening value is determined based on the process opening value and the initial maximum opening value.

[0007] Preferably, the target opening value is determined based on the process opening value and the initial maximum opening value, specifically as follows: The target opening value is determined based on the arithmetic mean of the process opening value and the initial maximum opening value.

[0008] Preferably, the target opening value is updated until the difference between the set value and the actual value meets the requirements, specifically: The difference between the target opening value and the process opening value is determined and denoted as the first value; The target opening value is updated based on the first value and the process opening value until the difference between the set value and the actual value meets the requirements.

[0009] Preferably, step 3 specifically includes: When the actual value of the steam temperature meets the preset conditions, the magnitude of the set value and the actual value of the steam temperature at this time is determined. When the set value is greater than the actual value, the current opening value of the desuperheating water regulating valve is determined as the minimum opening limit value for PID control. When the set value is less than or equal to the actual value, the current opening value of the desuperheating water regulating valve is determined as the maximum opening limit value for PID control.

[0010] Preferably, when the difference between the set value and the actual value is greater than a second threshold, the current opening value of the desuperheating water regulating valve is obtained, and a target opening value is determined based on the current opening value, specifically: Obtain the current opening value of the desuperheating water regulating valve; Determine the process opening value based on the current opening value of the desuperheating water regulating valve; The target opening value is obtained by halving the current opening value of the desuperheating water regulating valve.

[0011] Preferably, the target opening value is updated until the difference between the set value and the actual value meets the requirements, specifically: The difference between the process opening value and the target opening value of the desuperheating water regulating valve is determined to be half of the value, and is recorded as the second value. The target opening value is updated based on the difference between the process opening value of the desuperheating water regulating valve and the second value until the difference between the set value and the actual value meets the requirements.

[0012] Preferably, step 3 specifically includes: After the actual value of the steam temperature meets the preset condition, the magnitude of the set value and the actual value of the steam temperature at this time is determined. When the set value is greater than the actual value, the current opening value of the desuperheating water regulating valve is determined as the maximum opening limit value during PID control. When the set value is less than or equal to the actual value, the current opening value of the desuperheating water regulating valve is determined as the minimum opening limit for PID control.

[0013] A second aspect of the present invention provides a control system for desuperheating water in a thermal power plant based on the above-described control method for desuperheating water in thermal power plants, comprising: A parameter acquisition module is used to acquire the set value and the actual value of the steam temperature. The coarse adjustment module is used to coarsely adjust the opening value of the desuperheating water regulating valve when the difference between the set value and the actual value is less than a first threshold or greater than a second threshold, so that the actual value of the steam temperature meets the preset conditions. The limit determination module is used to determine the maximum opening limit and minimum opening limit of the desuperheating water regulating valve based on the opening value of the desuperheating water regulating valve when the actual value of the steam temperature meets the preset conditions. The fine-tuning module is used to fine-tune the opening value of the desuperheating water regulating valve by combining the maximum opening limit and the minimum opening limit when the difference between the set value and the actual value is between the first threshold and the second threshold.

[0014] The control method and system for desuperheating water in thermal power plants of the present invention have the following advantages compared with the prior art: The control method for desuperheating water in thermal power plants in this invention mainly consists of the combined action of the binary division method and PID control. The binary division method is used for coarse adjustment, which controls the opening of the desuperheating water regulating valve within a small range. Then, the fine adjustment is handed over to the PID controller, which finely adjusts the opening of the desuperheating water regulating valve within the small range defined by the binary division method. This can avoid large fluctuations in steam temperature and at the same time, it can quickly stabilize the steam temperature. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the overall structure of the control method for desuperheating water in a thermal power plant according to an embodiment of the present invention.

[0016] Figure 2 The diagram shows the results of controlling the temperature of the low-pressure shaft seal steam header using the desuperheating water control method of the present invention.

[0017] Figure 3 The graph shows the results of using PID control alone to control the temperature of the low-pressure shaft seal steam header. Detailed Implementation

[0018] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of the invention. However, those skilled in the art will understand that the invention can be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of the invention with unnecessary detail.

[0019] The first aspect of this invention provides a method for controlling desuperheating water in a thermal power plant, such as... Figure 1 As shown, it includes: Step 1: Obtain the steam temperature setpoint. and actual value .

[0020] This invention takes the desuperheating water of the low-pressure cylinder shaft seal of a steam turbine as an example, using a set value... Actual value of low-pressure cylinder shaft seal steam temperature The difference is used as a control parameter. Different channels are controlled based on the magnitude of this difference.

[0021] Step 2, when the set value Compared with actual value When the difference is less than the first threshold or greater than the second threshold, the opening value of the desuperheating water regulating valve is coarsely adjusted to ensure the actual steam temperature is within acceptable limits. The preset conditions are met.

[0022] First scenario: When the set value is... Compared with actual value When the difference is less than the first threshold, the opening value of the desuperheating water regulating valve is coarsely adjusted to ensure the actual steam temperature is within the threshold range. The preset conditions are met.

[0023] The first threshold can be -10℃, indicating that the temperature of the low-pressure cylinder shaft seal header is high, and the desuperheating water regulating valve needs to be opened wider.

[0024] At this point, the opening value of the desuperheating water regulating valve is coarsely adjusted to match the actual value of the steam temperature. The preset conditions are met, specifically: Step 2.1: Obtain the current opening value of the desuperheating water regulating valve. And based on the current opening value The target opening value is determined as follows: Step 2.1.1: Obtain the current opening value of the desuperheating water regulating valve. .

[0025] Step 2.1.2: Based on the current opening value of the desuperheating water regulating valve... Determine the process opening value and initial maximum opening value .

[0026] For example, when the current opening value of the desuperheating water regulating valve is... At that time, the initial maximum opening value When the current opening value of the desuperheating water regulating valve At that time, the initial maximum opening value .

[0027] Step 2.1.3: Based on the process opening value and initial maximum opening value Determine the target opening value.

[0028] Among them, based on the process opening value and initial maximum opening value Determine the target opening value, specifically based on the process opening value. Compared with the initial maximum opening value The arithmetic mean is used to determine the target opening value.

[0029] The process of determining the target opening value in this embodiment of the invention is essentially updating the current opening value. The process is as follows: Set the current opening value Assigning process variables and will Record this as the process opening value, and then issue a new opening command to the desuperheating water regulating valve: What was obtained at this time This is the target opening value.

[0030] Step 2.2: Determine the actual steam temperature during the process of adjusting the desuperheating water regulating valve to the target opening value within the preset time. The rate of change is used to update the target opening value until the set value is reached. When the rate of change reaches the first rate of change threshold, the target opening value is updated. Compared with actual value The difference meets the requirements.

[0031] In this embodiment of the invention, the preset time can be 120 seconds, the main purpose of which is to allow the steam temperature to stabilize for a period of time and reach a stable value.

[0032] In this embodiment of the invention, the first rate of change threshold can be 20°C / min, if the actual steam temperature is... If the rate of change reaches the first rate of change threshold, it indicates that the opening of the desuperheating water regulating valve is too large, causing the steam temperature to drop too quickly. At this point, the target opening value needs to be updated until the difference between the set value and the actual value meets the requirements. Specifically: Determine the target opening value and the process opening value The difference is denoted as the first value; Based on the first value and the process opening value Update the target opening value until the difference between the set value and the actual value meets the requirements.

[0033] For example, when the rate of change reaches a first rate of change threshold, the following steps are performed first: , The maximum opening limit of the desuperheating water regulating valve; then execute. After performing this operation, reduce the opening of the desuperheating water regulating valve and determine the actual steam temperature. Is it lower than the set value? If the temperature is above 10℃, it indicates that the opening of the desuperheating water regulating valve is too large. Repeat step 2.2 to reduce the valve opening. If the actual steam temperature is... With set value If the deviation is within 10℃, proceed to step 2.3.

[0034] Step 2.3, at the set value Compared with actual value Once the difference meets the requirements, determine the actual value of the steam temperature. If the rate of change is less than the second rate of change threshold, then the actual value of the steam temperature is considered to be... The preset conditions are met.

[0035] For example, the second rate of change threshold in an embodiment of the present invention can be 3°C / s.

[0036] In this embodiment of the invention, the actual value of the steam temperature With set value If the deviation is within 10℃, it is necessary to further determine whether the steam temperature is stable under the current opening degree of the desuperheating water regulating valve. Specifically, the derivative of the change in steam temperature with respect to time is calculated. If the absolute value of the derivative is <3℃ / s, it proves that the steam temperature has basically stabilized, and the next step can be performed. If the absolute value of the derivative is greater than 3℃ / s, steps 2.2 and 2.3 are repeated until the steam temperature stabilizes.

[0037] Step 3: Determine the maximum and minimum opening limits for PID control based on the opening value of the desuperheating water regulating valve when the actual steam temperature meets the preset conditions.

[0038] In the embodiments of the present invention, the actual value of steam temperature When the preset conditions are met, the actual value of the steam temperature is further determined. With set value Size.

[0039] When setting value Greater than the actual value When this occurs, it proves that the opening of the desuperheating water regulating valve is too small. Therefore, the opening value of the desuperheating water regulating valve at this time is assigned... , This refers to the minimum opening limit of the desuperheating water regulating valve. Used to limit the minimum opening of the desuperheating water regulating valve during PID control.

[0040] When setting value Less than or equal to the actual value At this time, it is proven that the opening of the desuperheating water regulating valve is too large, so the opening value of the desuperheating water regulating valve at this time is assigned to... , Used to limit the maximum opening of the desuperheating water regulating valve during the next step of PID control.

[0041] Step 4: When the difference between the set value and the actual value is between the first threshold and the second threshold, the opening value of the desuperheating water regulating valve is finely adjusted by combining the maximum opening limit and the minimum opening limit with PID control.

[0042] The second scenario in step 2 of this embodiment of the invention is as follows: When setting value Compared with actual value When the difference exceeds the second threshold, the low-pressure cylinder shaft seal steam temperature is too low, requiring the desuperheating water regulating valve to be closed slightly. Therefore, the opening value of the desuperheating water regulating valve needs to be coarsely adjusted to ensure the actual steam temperature is within acceptable limits. The preset conditions are met.

[0043] In this embodiment of the invention, the second threshold can be 10°C.

[0044] At this point, the opening value of the desuperheating water regulating valve is coarsely adjusted to match the actual value of the steam temperature. The preset conditions are met, specifically: Step S21: Based on the current opening value of the desuperheating water regulating valve Determine the process opening value, and based on the current opening value... Determine the target opening value.

[0045] The embodiments of the present invention set the process opening value Then, the current opening value of the desuperheating water regulating valve. Halve the target opening value. .

[0046] Step S22: Determine the rate of change of the actual value of steam temperature during the process of adjusting the desuperheating water regulating valve to the target opening value within a preset time. When the rate of change reaches the first rate of change threshold, update the target opening value until the difference between the set value and the actual value meets the requirements.

[0047] In this embodiment of the invention, the preset time can be 120 seconds, the main purpose of which is to allow the steam temperature to stabilize for a period of time and reach a stable value.

[0048] In this embodiment of the invention, the first rate of change threshold can be 20°C / min, if the actual steam temperature is... If the rate of change is greater than the first rate of change threshold, it indicates that the desuperheating water regulating valve is too small and needs to be opened wider. In this case, the target opening value needs to be updated until the difference between the set value and the actual value meets the requirements. Specifically: The second value is determined as half of the difference between the process opening value and the target opening value of the desuperheating water regulating valve. The target opening value is updated based on the difference between the process opening value of the desuperheating water regulating valve and the second value.

[0049] For example, first execute ; then execute Command. After this operation is completed, increase the opening of the desuperheating water regulating valve and determine the actual value of the steam temperature. Is it greater than the set value? If the temperature is above 10℃, repeat step S22. If the actual steam temperature is... With set value If the deviation is within 10°C, proceed to step S23.

[0050] Step S23: At the set value Compared with actual value Once the difference meets the requirements, determine the actual value of the steam temperature. If the rate of change is less than the second rate of change threshold, then the actual value of the steam temperature is considered to meet the preset conditions.

[0051] For example, the second rate of change threshold in an embodiment of the present invention can be 3°C / s.

[0052] In this embodiment of the invention, the actual value of the steam temperature With set value If the deviation is within 10℃, it is necessary to further determine whether the steam temperature is stable under the current opening degree of the desuperheating water regulating valve. Specifically, the derivative of the change in steam temperature with respect to time is calculated. If the absolute value of the derivative is <3℃ / s, it proves that the steam temperature has basically stabilized, and the next step can be performed. If the absolute value of the derivative is greater than 3℃ / s, steps S22 and S23 are repeated until the steam temperature stabilizes.

[0053] Step 3: Determine the maximum and minimum opening limits for PID control based on the opening value of the desuperheating water regulating valve when the actual steam temperature meets the preset conditions.

[0054] The actual value of steam temperature in the embodiments of the present invention After the preset conditions are met, the set value of the steam temperature is further determined. Compared with actual value Size.

[0055] When setting value Greater than the actual value At that time, assign the current opening value of the desuperheating water regulating valve. That is, When the set value Less than or equal to the actual value At that time, assign the current opening value of the desuperheating water regulating valve. That is, .

[0056] Step 4: When the difference between the set value and the actual value is between the first threshold and the second threshold, the opening value of the desuperheating water regulating valve is finely adjusted by combining the maximum opening limit and the minimum opening limit with PID control.

[0057] In this embodiment of the invention, when the set value Compared with actual value When the difference between the first and second thresholds is between the thresholds, PID control is used to fine-tune the opening value of the desuperheating water regulating valve. During the fine-tuning process, the opening value of the desuperheating water regulating valve needs to be between the maximum and minimum opening limits. When the setpoint of the steam temperature during the fine-tuning process... and actual value If the difference is greater than 20°C, return to step 1 and re-evaluate.

[0058] A second aspect of the present invention provides a control system for desuperheating water in a thermal power plant based on the above-described control method for desuperheating water in a thermal power plant, comprising a parameter acquisition module, a coarse adjustment module, a limit determination module, and a fine adjustment module.

[0059] The parameter acquisition module is used to obtain the set value and actual value of steam temperature.

[0060] The coarse adjustment module is used to coarsely adjust the opening value of the desuperheating water regulating valve when the difference between the set value and the actual value is less than the first threshold or greater than the second threshold, so that the actual value of the steam temperature meets the preset conditions.

[0061] The limit determination module is used to determine the maximum and minimum opening limits for PID control based on the opening value of the desuperheating water regulating valve when the actual value of the steam temperature meets the preset conditions.

[0062] The fine-tuning module is used to fine-tune the opening value of the desuperheating water regulating valve by combining the maximum opening limit and the minimum opening limit when the difference between the set value and the actual value is between the first threshold and the second threshold.

[0063] The control method for desuperheating water in thermal power plants according to embodiments of the present invention was applied to the low-pressure shaft seal desuperheating water in a power plant for trial use, and the control results were compared with those of simple PID control. The results are as follows: Figure 2 and Figure 3 As shown.

[0064] Depend on Figure 2 and Figure 3 As can be seen from the comparison, under the same PID control parameters, the temperature of the low-pressure cylinder shaft seal header controlled by the control method of this invention converges quickly and reaches equilibrium in about 30 minutes, while it takes more than 70 minutes to reach equilibrium by simple PID adjustment.

[0065] The control method for desuperheating water in thermal power plants in this invention mainly consists of the combined action of the binary method and PID control. The binary method is used for coarse adjustment, which controls the opening of the desuperheating water regulating valve within a small range. Then, the fine adjustment is handed over to the PID controller, which finely adjusts the opening of the desuperheating water regulating valve within the small range defined by the binary method. This can avoid large fluctuations in steam temperature and at the same time, it can quickly stabilize the steam temperature.

[0066] The above descriptions are merely a few embodiments of the present invention and are not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any modifications or alterations made by those skilled in the art without departing from the scope of the technical solution of the present invention using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for controlling desuperheating water in a thermal power plant, characterized in that, include: Step 1: Obtain the setpoint and actual value of the steam temperature; Step 2: When the difference between the set value and the actual value is less than the first threshold or greater than the second threshold, the opening value of the desuperheating water regulating valve is coarsely adjusted so that the actual value of the steam temperature meets the preset conditions. Step 3: Determine the maximum and minimum opening limits for PID control based on the opening value of the desuperheating water regulating valve when the actual value of the steam temperature meets the preset conditions; Step 4: When the difference between the set value and the actual value is between the first threshold and the second threshold, the opening value of the desuperheating water regulating valve is finely adjusted by combining the maximum opening limit and the minimum opening limit using PID control.

2. The method for controlling desuperheating water in a thermal power plant according to claim 1, characterized in that, The opening value of the desuperheating water regulating valve is coarsely adjusted to ensure that the actual steam temperature meets the preset conditions, specifically: Obtain the current opening value of the desuperheating water regulating valve, and determine the target opening value based on the current opening value; Within a preset time period, the rate of change of the actual value of steam temperature during the process of adjusting the desuperheating water regulating valve to the target opening value is determined. When the rate of change reaches a first rate of change threshold, the target opening value is updated until the difference between the set value and the actual value meets the requirements. After the difference between the set value and the actual value meets the requirements, the rate of change of the actual value of the steam temperature is determined. If the rate of change is less than the second rate of change threshold, the actual value of the steam temperature is considered to meet the preset conditions.

3. The method for controlling desuperheating water in a thermal power plant according to claim 2, characterized in that, When the difference between the set value and the actual value is less than a first threshold, the current opening value of the desuperheating water regulating valve is obtained, and the target opening value is determined based on the current opening value, specifically: Obtain the current opening value of the desuperheating water regulating valve; Based on the current opening value of the desuperheating water regulating valve, determine the process opening value and the initial maximum opening value; The target opening value is determined based on the process opening value and the initial maximum opening value.

4. The method for controlling desuperheating water in thermal power plants according to claim 3, characterized in that, The target opening value is determined based on the process opening value and the initial maximum opening value, specifically as follows: The target opening value is determined based on the arithmetic mean of the process opening value and the initial maximum opening value.

5. The method for controlling desuperheating water in a thermal power plant according to claim 3, characterized in that, Update the target opening value until the difference between the set value and the actual value meets the requirements, specifically: The difference between the target opening value and the process opening value is determined and denoted as the first value; The target opening value is updated based on the first value and the process opening value until the difference between the set value and the actual value meets the requirements.

6. The method for controlling desuperheating water in a thermal power plant according to any one of claims 3-5, characterized in that, Step 3 specifically involves: When the actual value of the steam temperature meets the preset conditions, the magnitude of the set value and the actual value of the steam temperature at this time is determined. When the set value is greater than the actual value, the current opening value of the desuperheating water regulating valve is determined as the minimum opening limit value for PID control. When the set value is less than or equal to the actual value, the current opening value of the desuperheating water regulating valve is determined as the maximum opening limit value for PID control.

7. The method for controlling desuperheating water in a thermal power plant according to claim 2, characterized in that, When the difference between the set value and the actual value is greater than the second threshold, the current opening value of the desuperheating water regulating valve is obtained, and the target opening value is determined based on the current opening value, specifically: Obtain the current opening value of the desuperheating water regulating valve; Determine the process opening value based on the current opening value of the desuperheating water regulating valve; The target opening value is obtained by halving the current opening value of the desuperheating water regulating valve.

8. The method for controlling desuperheating water in a thermal power plant according to claim 7, characterized in that, Update the target opening value until the difference between the set value and the actual value meets the requirements, specifically: The difference between the process opening value and the target opening value of the desuperheating water regulating valve is determined to be half of the value, and is recorded as the second value. The target opening value is updated based on the difference between the process opening value of the desuperheating water regulating valve and the second value until the difference between the set value and the actual value meets the requirements.

9. The method for controlling desuperheating water in a thermal power plant according to claim 7 or 8, characterized in that, Step 3 specifically involves: After the actual value of the steam temperature meets the preset condition, the magnitude of the set value and the actual value of the steam temperature at this time is determined. When the set value is greater than the actual value, the current opening value of the desuperheating water regulating valve is determined as the maximum opening limit value during PID control. When the set value is less than or equal to the actual value, the current opening value of the desuperheating water regulating valve is determined as the minimum opening limit for PID control.

10. A control system for desuperheating water in a thermal power plant based on the control method for desuperheating water in any one of claims 1-9, characterized in that, include: A parameter acquisition module is used to acquire the set value and the actual value of the steam temperature. The coarse adjustment module is used to coarsely adjust the opening value of the desuperheating water regulating valve when the difference between the set value and the actual value is less than a first threshold or greater than a second threshold, so that the actual value of the steam temperature meets the preset conditions. The limit determination module is used to determine the maximum opening limit and minimum opening limit of the desuperheating water regulating valve based on the opening value of the desuperheating water regulating valve when the actual value of the steam temperature meets the preset conditions. The fine-tuning module is used to fine-tune the opening value of the desuperheating water regulating valve by combining the maximum opening limit and the minimum opening limit when the difference between the set value and the actual value is between the first threshold and the second threshold.

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