Method for calculating background temperature of thermal discharge of coastal power plant, electronic device and storage medium

Abstract

The application discloses a kind of calculation method of coastal power plant warm discharge background temperature, electronic equipment and storage medium, accurately calculate background temperature, comprising:1.If there is power plant before running remote sensing image data, with power plant sea area as target sea area;If not, select adjacent, similar and not affected by warm discharge region of shoreline feature.2.Select and reverse the remote sensing image of the similar observation time, obtain the sea surface temperature data matrix.3.In the target sea area, the temperature mean value is calculated by establishing the water temperature gradient observation strip consistent with the resolution interval of remote sensing image along the coast to offshore direction.4.Based on the temperature data of observation strip, the curve representing the natural gradient change of offshore water temperature is fitted using the exponential function model.5.Introduce the reference point water temperature.6.Combined with the fitting curve and reference point water temperature, the background temperature of different tidal time and offshore distance is calculated to form a spatiotemporal continuous dynamic background temperature field.7.The actual temperature rise field of power plant warm discharge is obtained by difference operation between measured sea surface temperature field and dynamic background temperature field.

Description

Technical Field

[0001] This invention belongs to the field of marine environmental monitoring and remote sensing application technology, specifically referring to a method, electronic device and storage medium for calculating the background temperature of warm discharge from a coastal power plant, used to dynamically and accurately extract the seawater background temperature and assess the diffusion range and temperature rise of the warm discharge. Background Technology

[0002] With the increasing planning and construction of coastal power plants, the impact of warm wastewater on the marine environment is receiving growing attention. Accurately extracting the background temperature is crucial for evaluating the diffusion range and temperature rise of warm wastewater. Currently, background temperature determination mainly relies on the following methods, but all have significant limitations:

[0003] Fixed-point reference method: The temperature of one or more fixed points far from the outlet is selected as the background value for the entire study area. This method completely ignores the spatial heterogeneity of ocean temperature (especially the gradient change from nearshore to offshore), and will introduce large errors in areas with complex coastlines.

[0004] Spatial interpolation: This method uses measured data from a limited number of stations to generate a spatially continuous background temperature field through interpolation algorithms. Although it considers spatial distribution, it heavily relies on expensive and sparse field observation data, making it difficult to apply on a large scale and at high frequency. It is also difficult to accurately characterize natural offshore temperature gradients.

[0005] Remote sensing inversion method: This method directly uses the sea surface temperature (SST) map from a single remote sensing image, treating the temperature of the area far from the discharge outlet as background. While remote sensing imagery can provide sea surface temperature data over a wide area, it cannot reflect the dynamic changes in sea surface temperature during the tidal cycle, resulting in a "static" background temperature that cannot meet the assessment requirements for the dynamic diffusion of warm discharge. Furthermore, this method also fails to consider the background water temperature gradient changes from nearshore to offshore.

[0006] Therefore, existing technologies generally have the drawback of being unable to simultaneously characterize the spatial gradient characteristics of regional temperature and the dynamic changes over time (tidal cycle), resulting in inaccurate background temperature extraction and thus affecting the reliability of the environmental impact assessment of thermal drainage. Summary of the Invention

[0007] The main objective of this invention is to provide a method, electronic device, and storage medium for calculating the background temperature of thermal discharge from a coastal power plant, thereby solving the problems existing in the prior art and achieving high-precision calculation of the background temperature.

[0008] To achieve the above objectives, one solution of the present invention is:

[0009] A method for calculating the background temperature of thermal discharge from a coastal power plant includes the following steps:

[0010] Step 1: If there is remote sensing image data before the power plant is put into operation, the sea area of ​​the power plant is directly used as the target sea area; if there is no remote sensing image data before the power plant is put into operation, a characteristic area within 100km away from the sea area of ​​the power plant, which is an open sea area or a semi-enclosed sea area with the coastline of the power plant and is not affected by the warm discharge is selected as the target sea area.

[0011] Step 2: Select the remote sensing image that is from the same season as the field observation and whose imaging time is closest to that of the field observation, and perform inversion on the remote sensing image to obtain the sea surface temperature data matrix;

[0012] Step 3: Establish water temperature gradient observation strips along the coast and offshore in the target sea area, with the same resolution interval as the remote sensing images used, and calculate the average temperature in each strip based on the sea surface temperature data matrix.

[0013] Step 4: Based on the temperature data of the observed strips, an exponential function model is used to fit a curve representing the natural gradient change of offshore water temperature;

[0014] Step 5: Introduce the reference point water temperature. The reference point is selected from the offshore area outside the power plant's submerged discharge area, where it is not affected by the temperature discharge.

[0015] Step 6: Combine the fitted curve with the water temperature at the reference point to calculate the background temperature at different tide times and different distances from the shore, forming a spatiotemporally continuous dynamic background temperature field.

[0016] Step 7: Perform difference calculation between the measured sea surface temperature field and the dynamic background temperature field to obtain the actual temperature rise field caused by the power plant's thermal discharge, delineate the temperature rise range, and count the affected area of ​​different temperature rise levels.

[0017] The curve expression fitted in step 4 is as follows:

[0018] ;

[0019] in, Indicates offshore The average temperature within the band; This represents the temperature value at which the temperature eventually stabilizes as the temperature changes with distance from the shore. , These represent two characteristic parameters that reflect the pattern of offshore temperature variation; , and The values ​​were all obtained through fitting.

[0020] Preferably, the expression for temperature calculation in step 6 is as follows:

[0021] ;

[0022] in, Indicates offshore Background temperature at the location; Indicates the reference point Water temperature; Indicates the reference point The location.

[0023] Preferably, when there are multiple reference points, the average calculation is performed by including all reference points, and the expression is as follows:

[0024] ;

[0025] in, Indicates offshore integration of all benchmarks Background temperature at the location; Indicates the total number of reference points; Indicates the serial number of the reference point.

[0026] Preferably, the expressions for the temperature rise and the affected area in step 7 are as follows:

[0027] ;

[0028] ;

[0029] in, Indicates offshore The water temperature at that location increased; Indicates offshore The measured temperature value at the location; Represents the area of ​​the polygon affected by the temperature distribution; Represents the vertex coordinates of the polygon. Indicates the index of the vertex coordinates.

[0030] The second solution of the present invention is:

[0031] An electronic device includes a processor, a memory, and an application program; the application program is stored in the memory and configured to be executed by the processor using the method for calculating the background temperature of the thermal discharge from a coastal power plant.

[0032] The third solution of the present invention is:

[0033] A computer-readable storage medium storing a computer program; when executed in the computer, the computer program causes the computer to perform the method for calculating the background temperature of the thermal discharge from the coastal power plant.

[0034] After adopting the above technical solution, the present invention has the following technical effects:

[0035] (a) Select the target sea area according to the actual situation, and calculate the background temperature of the thermal discharge of the operating power plant by fitting the curve of the water temperature distribution in the target sea area. Only a single remote sensing image and at least one measured water temperature data that is not affected by the thermal discharge are needed as a reference point for calculation. It has the advantages of low data requirements and simple operation.

[0036] (b) By fitting characteristic parameters and combining measured data, it overcomes the shortcomings of other methods that cannot reflect the regional background temperature distribution pattern with a single value. It can also dynamically characterize the real-time impact of the ebb and flow of tides on the background temperature based on the temperature difference of different tidal reference points, and reflect the changes in background temperature on a smaller time scale. Attached Figure Description

[0037] Figure 1 This is a flowchart of a specific embodiment of the present invention.

[0038] Figure 2 This is a schematic diagram of the observation strip construction according to a specific embodiment of the present invention.

[0039] Figure 3 This is a schematic diagram of offshore thermal gradient curve fitting according to a specific embodiment of the present invention, where the scatter points are remote sensing measured data and the curve is the fitting result.

[0040] Figure 4 This is a background temperature distribution diagram during the rapid rise of a specific embodiment of the present invention.

[0041] Figure 5 This is a background temperature distribution diagram at the moment of descent, according to a specific embodiment of the present invention.

[0042] Figure 6 This is a temperature rise distribution diagram of a power plant during a rapid temperature increase, calculated using the method of this invention.

[0043] Figure 7 This is a temperature rise distribution diagram of a power plant at the moment of sudden drop, calculated using the method of this invention. Detailed Implementation

[0044] To further explain the technical solution of the present invention, the present invention will be described in detail below through specific embodiments.

[0045] This invention discloses an offshore thermal gradient exponential fitting method (OTGEM), which achieves high-precision calculation of background temperature by constructing a gradient observation strip and a natural gradient curve model.

[0046] refer to Figure 1 As shown, a method for calculating the background temperature of thermal discharge from a coastal power plant includes the following steps:

[0047] Step 1. Select the target sea area: If remote sensing image data before the power plant's operation is available, the sea area of ​​the power plant can be directly used as the target sea area; if remote sensing image data before the power plant's operation is not available, select a characteristic area within 100km of the power plant's sea area that is an open sea area (affected by a single coastline) or a semi-enclosed sea area (affected by a double coastline) and is not affected by warm discharge as the target sea area.

[0048] Step 2. Historical remote sensing data preparation and preprocessing: Select remote sensing images that are from the same season as the field observations and whose imaging time is closest to the field observations, and perform inversion on the remote sensing images to obtain the sea surface temperature (SST) data matrix.

[0049] Step 3. Establish observation strips: Along the coast of the target sea area, establish water temperature gradient observation strips with the same resolution intervals as the remote sensing images used, and calculate the average temperature within each strip based on the sea surface temperature data matrix. The strip width is determined by the spatial resolution of the remote sensing images and the coastline morphology of the target sea area, while the length is determined by the boundary extent of the thermal discharge influence in the study area.

[0050] Step 4. Fitting the Offshore Thermal Gradient Curve: Based on the temperature data from the observed strips, an exponential function model is used to fit a curve representing the natural gradient change of offshore water temperature. Specifically, the expression for the curve is as follows:

[0051] ;

[0052] in, Indicates offshore Average temperature (°C) within the band; This represents the temperature value (°C) at which the temperature eventually stabilizes as the distance from the shore changes. , These represent two characteristic parameters that reflect the pattern of offshore temperature changes, and their values ​​vary depending on the spatiotemporal conditions. , and The values ​​were all obtained through fitting.

[0053] Step 5. Application of the benchmark point: A benchmark point water temperature is introduced. The benchmark point is selected from an offshore location outside the power plant's submerged discharge area, unaffected by the temperature discharge. The benchmark point covers the water temperature changes during high and low tides within the tidal cycle. Introducing the benchmark point reflects the real-time impact of tides on the background temperature, thereby enabling dynamic calculation of the background temperature.

[0054] Step 6. Background Temperature Field Calculation: Combine the fitted curve with the water temperature at the reference point to calculate the background temperature at different tide times and distances from the shore, forming a spatiotemporally continuous dynamic background temperature field. Specifically, the expression for temperature calculation is as follows:

[0055] ;

[0056] in, Indicates offshore Background temperature (°C) at that location; Indicates the reference point Water temperature (°C); Indicates the reference point The location.

[0057] Furthermore, when there are multiple reference points, all reference points can be included in the average calculation, and the expression is as follows:

[0058] ;

[0059] in, Indicates offshore integration of all benchmarks Background temperature (°C) at that location; Indicates the total number of reference points; Indicates the serial number of the reference point.

[0060] Step 7. Temperature Rise Calculation and Impact Assessment: The difference between the measured sea surface temperature field and the dynamic background temperature field is calculated to obtain the actual temperature rise field caused by the power plant's thermal discharge, thereby accurately delineating the temperature rise range (e.g., isotherms for ≥0.5°C, ≥1°C, and ≥2°C), and statistically analyzing the impact area for different temperature rise levels. Specifically, the expressions for temperature rise value and impact area are as follows:

[0061] ;

[0062] ;

[0063] in, Indicates offshore Water temperature rise at the location (°C); Indicates offshore Measured temperature value (°C) at the location; Represents the area of ​​the polygon affected by the temperature distribution; Represents the vertex coordinates of the polygon. Indicates the index of the vertex coordinates.

[0064] Through the above solution, the present invention can achieve the following technical effects:

[0065] (1) Dynamic characterization of tidal influence: By associating the tidal cycle with the reference point, the real-time influence of rising and falling tides on the background temperature can be characterized.

[0066] (2) Adapting to regional characteristics: Based on offshore thermal gradient fitting, it fundamentally respects the spatial distribution law of seawater temperature. The method principle does not depend on specific coastline morphology and can accurately reflect the natural temperature distribution of different coastline types (such as open sea areas and semi-enclosed bays).

[0067] (3) High calculation accuracy: Error analysis shows that the average error of background temperature calculation can be less than 0.2°C in areas more than 1 kilometer offshore.

[0068] (4) Low data requirements and easy operation: Only historical remote sensing images and limited measured data are needed. The process is clear and can be automated through programming. It is easy to operate and convenient for engineering applications.

[0069] The following uses the sea area of ​​a coastal power plant as an example to illustrate the specific implementation process of the present invention.

[0070] (I) Since there is no remote sensing image data of the power plant before its operation, a nearby area with similar coastline characteristics to the power plant's sea area and unaffected by warm discharge is selected as the target sea area. In this embodiment, the selected nearby area is located approximately 5 km SW from the power plant's sea area.

[0071] (II) Select the remote sensing image that is from the same season as the field observation and whose imaging time is closest to that of the field observation, and process it to obtain sea surface temperature (SST) data. In this embodiment, the field observation time is February 2023, and the remote sensing image time is February 2021.

[0072] (III) See Figure 2 On the SST data, observation strips with 30m intervals were set along the power plant's discharge outlet towards the shore (perpendicular to the shoreline). The width of the strips was consistent with the shoreline range of the study area, extending to 4km offshore.

[0073] (IV) Average the temperature of each image data strip to obtain the temperature value at each distance point in the offshore direction. Use an exponential function. By fitting the data, the background thermal gradient curve for this sea area was obtained. (See also...) Figure 3 In this embodiment, the fitted curve expression is: The fitting results show that the curve naturally decreases from nearshore to offshore, with the temperature difference between 300m nearshore and 4000m offshore being approximately 1.3°C.

[0074] (V) Calculate the dynamic background temperature field by applying the benchmark water temperature and combining it with the fitted curve. First, calculate the offshore temperature field based on the fitted curve expression from step (IV). and water temperature and Then apply the reference point water temperature From the formula Calculation of offshore Background temperature at the location Finally, This is applied across the entire study area to generate a spatially continuous dynamic background temperature field. See also... Figure 4 , 5 In this embodiment, the reference point is located 2.4 km offshore from the power plant's sea area. The reference point water temperature data is collected continuously for 27 hours, with one set of data per hour, covering two complete tidal cycles: high tide and low tide. The results in the figure show that the background temperature field exhibits a significant offshore gradient variation and is dynamically changing due to the influence of the tidal cycle. The overall difference in background water temperature between the inner and outer areas of the study area is approximately 0.9°C.

[0075] (VI) See Figure 6 , 7 We obtained measured SST data from the spring tides of February 6-7, 2023, and subtracted it from the dynamic background temperature field generated in step (V) to obtain the temperature rise field. The analysis showed that the temperature rise range of each level at different tide times was smaller than the result calculated using the single-point reference method, and the plume morphology was more in line with the laws of hydrodynamics, making the assessment results more reasonable and reliable.

[0076] The present invention also discloses an electronic device, including a processor, a memory, and an application program; the application program is stored in the memory and configured to be executed by the processor using the methods described above.

[0077] The present invention also discloses a computer-readable storage medium storing a computer program; when the computer program is executed in a computer, it causes the computer to perform the above-described method. The storage medium may include various media capable of storing program code, such as a USB flash drive, portable hard drive, read-only memory (ROM), random access memory (RAM), magnetic disk, or optical disk.

[0078] The above embodiments and figures are not intended to limit the product form and style of the present invention. Any appropriate changes or modifications made by those skilled in the art should be considered as not departing from the patent scope of the present invention.

Claims

1. A method for calculating the background temperature of thermal discharge from a coastal power plant, characterized in that, Includes the following steps: Step 1: If there is remote sensing image data before the power plant is put into operation, the sea area of ​​the power plant is directly used as the target sea area; if there is no remote sensing image data before the power plant is put into operation, a characteristic area within 100km away from the sea area of ​​the power plant, which is an open sea area or a semi-enclosed sea area with the coastline of the power plant and is not affected by the warm discharge is selected as the target sea area. Step 2: Select the remote sensing image that is from the same season as the field observation and whose imaging time is closest to that of the field observation, and perform inversion on the remote sensing image to obtain the sea surface temperature data matrix; Step 3: Establish water temperature gradient observation strips with the same resolution interval as the remote sensing images used in the target sea area, in the direction from the coast to the shore, that is, in the direction perpendicular to the coastline, and calculate the average temperature in each strip based on the sea surface temperature data matrix. Step 4: Based on the temperature data from the observed strips, an exponential function model is used to fit a curve representing the natural gradient change of offshore water temperature; the curve expression is as follows: ;in, Indicates offshore The average temperature within the band; This represents the temperature value at which the temperature eventually stabilizes as the temperature changes with distance from the shore. , These represent two characteristic parameters that reflect the pattern of offshore temperature variation; , and The values ​​were all obtained through fitting. Step 5: Introduce the reference point water temperature. The reference point is selected from the offshore area outside the power plant's submerged discharge area, where it is not affected by the temperature discharge. Step 6: Combine the fitted curve with the water temperature at the benchmark point to calculate the background temperature at different tide times and different distances from the shore, forming a spatiotemporally continuous dynamic background temperature field; the expression for temperature calculation is as follows: ;in, Indicates offshore Background temperature at the location; Indicates the reference point Water temperature; Indicates the reference point Location; Step 7: Perform difference calculation between the measured sea surface temperature field and the dynamic background temperature field to obtain the actual temperature rise field caused by the power plant's thermal discharge, delineate the temperature rise range, and count the affected area of ​​different temperature rise levels.

2. The method for calculating the background temperature of thermal discharge from a coastal power plant as described in claim 1, characterized in that, When there are multiple reference points, all reference points are included in the average calculation, and the expression is as follows: ； in, Indicates the integration of all benchmarks for offshore operations. Background temperature at the location; Indicates the total number of reference points; Indicates the serial number of the reference point.

3. The method for calculating the background temperature of thermal discharge from a coastal power plant as described in claim 2, characterized in that, The expressions for the temperature rise and the affected area in step 7 are as follows: ； ； in, Indicates offshore The water temperature at that location increased; Indicates offshore The measured temperature value at the location; Represents the area of ​​the polygon affected by the temperature distribution; Represents the vertex coordinates of the polygon. Indicates the index of the vertex coordinates.

4. An electronic device, characterized in that... It includes a processor, a memory, and an application program; the application program is stored in the memory and configured to be executed by the processor using the method for calculating the background temperature of the thermal discharge from the coastal power plant as described in any one of claims 1 to 3.

5. A computer-readable storage medium, characterized in that... The storage medium stores a computer program; when the computer program is executed in the computer, it causes the computer to perform the method for calculating the background temperature of the thermal discharge from the coastal power plant as described in any one of claims 1 to 3.

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