A method for estimating the balanced water depth of a drainage channel of a power plant

Abstract

The application discloses a method for estimating balance water depth of a power plant drainage open channel, comprising the following steps: obtaining full-tide hydrological measured historical data of a water area where the power plant is located; based on the historical data, performing data fitting on the balance water depth and the unit width flow to obtain a fitting curve; constructing a tidal current model and performing tidal current simulation calculation based on the tidal current model to obtain a tidal current simulation calculation result; based on the tidal current simulation calculation result, selecting open channel characteristic points and calculating the unit width flow at the positions of the characteristic points based on the open channel characteristic points; based on the fitting curve and the unit width flow at the positions of the characteristic points, calculating the balance water depth values of the open channel characteristic points to obtain an open channel balance water depth result. The application can be applied to an undeveloped sea area, the error of the estimation result of the balance water depth is low, and the estimation method is simple and effective.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of balanced water depth measurement, and particularly relates to a method for estimating balanced water depth of a water intake and discharge channel of a power plant. BACKGROUND

[0002] When the seabed is stable, the water depth, dynamic conditions (waves and currents) and sediment content are basically in a relatively balanced state, and the water depth at this time is referred to as the balanced water depth. Influenced by engineering construction, the water flow and wave power in the local water area of the project will change, thereby causing the sediment content of the water body to change, and the water depth will also be adjusted to adapt to the new balanced state.

[0003] In recent decades, the state has vigorously developed coastal power plants, and the power plants need to take in cold water from the open sea and discharge warm water to maintain the basic operation of the power plant. Influenced by many factors, the power plant needs to build a water intake and discharge breakwater and excavate a water intake and discharge channel in the breakwater to ensure the smooth water intake and discharge of the power plant. Considering the construction of the breakwater, the excavation of the channel and the influence of water intake and discharge, the dynamic conditions in the water intake and discharge channel will change, and the water depth will also be adjusted, and after a certain period of time, a new balanced water depth will be reached. If the bottom elevation of the channel after adjusting the water depth is higher than the design datum low water level, the power plant will have a safety problem in water intake and discharge, and therefore, calculating the balanced water depth in the water intake and discharge channel of the power plant is crucial to the safety of water intake and discharge during the operation of the power plant. In the past, the research on the balanced water depth in the water intake and discharge channel after the construction of the power plant mostly used a numerical simulation research method of long-period topographic evolution, but this method is not mature and mainly relies on the topographic changes after the implementation of the adjacent project as the verification data of topographic erosion and deposition. If the surrounding sea area is an undeveloped sea area, this calculation method has a large error. Therefore, the present application attempts to find a new and simple calculation method to calculate the balanced water depth in the channel. SUMMARY

[0004] To achieve the above object, the application provides the following scheme: a method for estimating the balanced water depth of a water intake and discharge channel of a power plant, comprising:

[0005] obtaining full-tide hydrological measured historical data of a water area where the power plant is located, fitting the balanced water depth and the unit width flow based on the historical data to obtain a fitting curve;

[0006] constructing a tidal current model and performing tidal current simulation calculation based on the tidal current model to obtain a tidal current simulation calculation result;

[0007] selecting a channel feature point based on the tidal current simulation calculation result, and calculating the unit width flow at the position of the feature point based on the channel feature point;

[0008] calculating the balanced water depth value of the channel feature point based on the fitting curve and the unit width flow at the position of the feature point to obtain a channel balanced water depth result.

[0009] Preferably, the process of obtaining historical hydrological data of the waters where the power plant is located includes collecting the equilibrium water depth of each station, the average flow velocity of each station during spring tide, mid-tide, and neap tide; and obtaining the flow rate of each station's cross-section based on the equilibrium water depth and the average flow velocity.

[0010] Preferably, the formula for the fitted curve is:

[0011] y = 5.907x 0.5367

[0012] Where: x is the unit width flow rate, and y is the equilibrium water depth.

[0013] Preferably, the process of constructing the power flow model includes software selection, determining the computational domain, mesh generation, determining open boundaries, and model verification.

[0014] Preferably, the mesh subdivision is used to fit detailed boundaries including complex headlands, estuaries, and breakwaters;

[0015] The meshing process includes: locally densifying the model computation network in key engineering areas; using an unstructured triangular network to partition the computation domain to obtain the minimum spatial step size of the model mesh; and dividing the model network nodes for final computation based on the minimum spatial step size of the model mesh. The minimum spatial step size of the model mesh should ensure accurate differentiation of water intake and drainage channels.

[0016] Preferably, when performing tidal current simulation calculations based on the tidal current model, the process further includes determining the open boundary and specifying the tidal level or tidal volume of the open boundary.

[0017] The process of determining the open boundary and giving the tidal level or tidal volume of the open boundary includes controlling the open sea tide at the open boundary using the tidal level process, calculating the tidal level boundary based on the tidal model, and adjusting it according to the measured flow velocity and direction.

[0018] Preferably, the process of calculating the unit width flow rate at the feature point location based on the open channel feature points includes: simulating the water flow dynamics after the power plant is implemented based on a verified tidal flow model and extracting the average flow velocity and water depth at each feature point; and obtaining the flow rate in the open channel based on the average flow velocity and water depth.

[0019] The present invention discloses the following technical effects:

[0020] This invention provides a method for estimating the equilibrium water depth of an open channel for the intake and discharge of a power plant. The method involves collecting historical hydrological data from the waters where the power plant is located, fitting the equilibrium water depth and unit width discharge to obtain a fitted curve; selecting characteristic points in the open channel and calculating the unit width discharge at those points; and finally, obtaining the equilibrium water depth based on the fitted curve and the unit width discharge at the characteristic points. This invention can be applied to undeveloped sea areas, provides low error in the estimation of equilibrium water depth, and is simple and effective. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a flowchart of a method according to an embodiment of the present invention;

[0023] Figure 2 This is a schematic diagram of the water intake and drainage project according to an embodiment of the present invention;

[0024] Figure 3 This is a fitting curve diagram between the equilibrium water depth and unit width flow rate in an embodiment of the present invention;

[0025] Figure 4 This is a schematic diagram of the computational domain and mesh partitioning in an embodiment of the present invention;

[0026] Figure 5 This is a schematic diagram of a local mesh of the model in an embodiment of the present invention;

[0027] Figure 6 This is a tide level verification diagram according to an embodiment of the present invention;

[0028] Figure 7 This is a diagram verifying the current velocity and direction of the tidal current in an embodiment of the present invention.

[0029] Figure 8 This is a diagram verifying the tidal current velocity and direction in an embodiment of the present invention.

[0030] Figure 9 This is a diagram verifying the current velocity and direction of a small current according to an embodiment of the present invention.

[0031] Figure 10 This is a schematic diagram of the feature point locations according to an embodiment of the present invention;

[0032] Figure 11 This is a balanced water depth diagram of characteristic points in the open intake and drainage channel according to an embodiment of the present invention. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] like Figure 1 As shown, the present invention provides a method for estimating the equilibrium water depth of an open intake and drainage channel in a power plant, comprising:

[0036] Obtain historical hydrological data of the water area where the power plant is located, and perform data fitting on the equilibrium water depth and unit width flow rate based on the historical data to obtain the fitting curve;

[0037] Construct a current flow model, perform current flow simulation calculations based on the current flow model, and obtain the current flow simulation calculation results;

[0038] Based on the power flow simulation results, open channel feature points are selected, and the unit width flow rate at the feature point location is calculated based on the open channel feature points.

[0039] Based on the fitted curve and the unit width flow rate at the location of the feature point, the equilibrium water depth value of the feature point in the open channel is calculated to obtain the equilibrium water depth result of the open channel.

[0040] The process of obtaining historical hydrological data of the waters where the power plant is located includes collecting the equilibrium water depth of each station, the average flow velocity of each station during spring tide, mid-tide, and neap tide; and obtaining the flow rate of each station's cross-section based on the equilibrium water depth and the average flow velocity.

[0041] The formula for the fitted curve is:

[0042] y = 5.907x 0.5367

[0043] Where: x is the unit width flow rate, and y is the equilibrium water depth.

[0044] The process of constructing the power flow model includes software selection, determination of the computational domain, mesh generation, determination of open boundaries, and model verification.

[0045] The mesh subdivision is used to fit detailed boundaries including complex headlands, estuaries, and breakwaters;

[0046] The meshing process includes: locally densifying the model computation network in key engineering areas; using an unstructured triangular network to partition the computation domain to obtain the minimum spatial step size of the model mesh; and dividing the model network nodes for final computation based on the minimum spatial step size of the model mesh. The minimum spatial step size of the model mesh should ensure accurate differentiation of water intake and drainage channels.

[0047] When performing tidal current simulation calculations based on the aforementioned tidal current model, the process also includes determining the open boundary and specifying the tidal level or tidal volume of the open boundary.

[0048] The process of determining the open boundary and giving the tidal level or tidal volume of the open boundary includes controlling the open sea tide at the open boundary using the tidal level process, calculating the tidal level boundary based on the tidal model, and adjusting it according to the measured flow velocity and direction.

[0049] The process of calculating the unit width flow rate at the feature point location based on the open channel feature points includes: simulating the water flow dynamics after the power plant is implemented based on a verified tidal flow model and extracting the average flow velocity and water depth at each feature point; and obtaining the flow rate in the open channel based on the average flow velocity and water depth.

[0050] Example 1

[0051] Furthermore, the actual application process of the method of the present invention will be introduced below using a power plant as an example.

[0052] 1. Introduction to Power Plant Intake and Drainage Engineering

[0053] like Figure 2 The following example illustrates the water intake and drainage scheme of a power plant. The power plant adopts a scheme of "water intake on the south side and drainage on the north side, with open channel intake and drainage." The drainage channel is 25m wide and 145m long, with a designed bottom elevation of -8.8m (85m elevation datum). The water intake channel is 110m wide, with a designed bottom elevation of -7.8m (85m elevation datum). The power plant has two generating units, with each unit's water intake and drainage volume tentatively set at 33m³ / h. 3 / s.

[0054] 2. Fitting the relationship between equilibrium water depth and unit width flow rate

[0055] Due to the wave-blocking effect of the breakwater in the water intake and drainage project, the waves in the power plant's water intake and drainage open channel are very small. Therefore, after the power plant is actually in operation, the equilibrium water depth in the open channel is mainly controlled by the flow rate of the power plant's water intake and drainage and the external tidal forces. Therefore, it is necessary to first find the relationship between the equilibrium water depth and the flow rate per unit width.

[0056] Considering that the water depth near the project site can be regarded as the equilibrium depth under natural conditions, the water depth (85 datum) of each station during the hydrological survey of the sea area near the project site and the unit width discharge (unit width discharge = average flow velocity × water depth) during the spring, mid, and neap tide hydrological data measurement period of each station were used for fitting. The goodness of the fitting relationship directly determines the accuracy of the subsequent estimation of the equilibrium depth in the open channel. The calculation results of water depth and unit width discharge at each station are shown in Table 1.

[0057] Table 1

[0058]

[0059]

[0060] Figure 3 The fitted curves between the equilibrium water depth and the unit width flow rate for this project are presented. It can be seen that the curve fits well, with a goodness of fit R0. 2 It can reach 0.9302. The formula for the fitted curve is:

[0061] y = 5.907x 0.5367 (1)

[0062] Where: x is the unit width flow rate, and y is the equilibrium water depth.

[0063] 3. Numerical simulation to solve the unit width flow rate of open channels

[0064] (1) Software selection

[0065] The mathematical model used in the numerical simulation is mainly a power flow model, and the calculation software mainly adopts the internationally used MIKE21 / FM module.

[0066] (2) Determination of computational domain

[0067] See the mathematical model calculation range. Figure 4 The model centers on the project area, with the open sea boundary approximately 60 km offshore. The coastline was determined using the latest satellite imagery, and the topography was based on multiple nautical charts and the latest measured depth maps of the vicinity of the project site.

[0068] (3) Mesh generation

[0069] To fit the detailed boundaries of complex headlands, estuaries, and dikes, the tidal current mathematical model uses an unstructured triangular mesh to partition the computational domain (the computational mesh in key engineering areas is locally refined to meet the computational accuracy requirements and ensure sufficient resolution). The minimum spatial step size of the model mesh should ensure accurate resolution of intake and drainage channels. Figure 4 The diagram illustrates the computational grid of the model. Figure 5 The schematic diagram shows a local mesh of the model. The model used for the final calculation has approximately 16,985 mesh nodes, with the smallest mesh size being nearly 5.0m.

[0070] (4) Determining the open boundary

[0071] When performing tidal current simulation calculations, it is necessary to specify the tidal level or tidal volume process at the open boundary. In this model, the open boundary offshore tidal waves are controlled by the tidal level process, and the tidal level boundary is calculated by the ChinaTide tidal model and then adjusted according to the measured current velocity and direction.

[0072] (5) Model Validation

[0073] To verify the accuracy of the tidal current model calculations, hydrological full-tidal observation data were used to validate the model's tidal level, current velocity, and flow direction processes. The validation curves are shown in [reference needed]. Figures 6-9 (Circles represent measured data, and solid lines represent verification results). Through model calculations, it is believed that the calculated tidal level, flow velocity, and flow direction at each station are close to the measured values ​​during continuous changes, and the verification results of the vast majority of measuring points meet the requirements of the current "Technical Specification for Simulation Tests of Water Transport Engineering".

[0074] (6) Selection of characteristic points of open channel

[0075] A total of 31 feature points were selected within the open intake and drainage channels, with 26 selected in the intake channel and 5 in the drainage channel. For specific locations, please refer to [link to relevant documentation]. Figure 10 .

[0076] (7) Unit width flow rate at characteristic point location of open channel

[0077] Based on the previously verified mathematical model, the hydrodynamics of the power plant after implementation were simulated, and the average flow velocity (averaged over time) and water depth at each characteristic point were extracted. The flow rate in the open channel is then calculated as average flow velocity × water depth. See Table 2 for specific results.

[0078] Table 2

[0079] Characteristic point Mean current velocity of full tide Design water depth Discharge per unit width Equilibrium water depth 1# 0.034 7.80 0.27 2.9 2# 0.036 7.80 0.28 3.0 3# 0.036 7.80 0.28 3.0 4# 0.042 7.80 0.33 3.2 5# 0.018 7.80 0.14 2.0 6# 0.036 7.80 0.28 3.0 7# 0.057 7.80 0.44 3.8 8# 0.021 7.80 0.16 2.2 9# 0.036 7.80 0.28 3.0 10# 0.053 7.80 0.41 3.7 11# 0.026 7.80 0.20 2.5 12# 0.034 7.80 0.26 2.9 13# 0.046 7.80 0.36 3.4 14# 0.031 7.80 0.24 2.8 15# 0.027 7.80 0.21 2.6 16# 0.063 7.80 0.49 4.0 17# 0.052 7.80 0.40 3.6 18# 0.037 7.80 0.29 3.0 19# 0.057 7.80 0.44 3.8 20# 0.064 7.80 0.50 4.1 21# 0.069 7.80 0.54 4.2 22# 0.048 7.80 0.37 3.5 23# 0.053 7.80 0.41 3.7 24# 0.080 7.80 0.62 4.6 25# 0.068 7.80 0.53 4.2 26# 0.052 7.80 0.41 3.6 27# 0.318 8.80 2.80 10.3 28# 0.285 8.80 2.50 9.7 29# 0.233 8.80 2.05 8.7 30# 0.166 8.80 1.46 7.2 31# 0.153 8.80 1.34 6.9

[0080] 4. Calculation of equilibrium water depth in open channels

[0081] The equilibrium water depth at each point is calculated according to formula (1), as detailed in Table 2 and... Figure 11 .visible:

[0082] (1) The equilibrium water depth in the water intake channel is basically between -2.0 and -4.6m, and the equilibrium water depth tends to be greater closer to the water intake channel inlet.

[0083] (2) The equilibrium water depth in the drainage channel is between -6.9 and -10.3 m, showing a trend of increasing equilibrium water depth closer to the drainage outlet.

[0084] (3) Based on the equilibrium water depth calculation, the water intake channel shows a siltation trend, with a siltation range of 3.2 to 5.8 meters. The drainage channel shows both scouring and silting, with the local water area at the drainage outlet scouring to about 1.5 meters, while the drainage channel is basically in a siltation state further out, with a siltation range of 0.1 to 1.9 meters.

[0085] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for estimating the equilibrium water depth of an open intake and drainage channel in a power plant, characterized in that, include: Obtain historical hydrological data of the water area where the power plant is located, and perform data fitting on the equilibrium water depth and unit width flow rate based on the historical data to obtain the fitting curve; Construct a current flow model, perform current flow simulation calculations based on the current flow model, and obtain the current flow simulation calculation results; Based on the power flow simulation results, open channel feature points are selected, and the unit width flow rate at the feature point location is calculated based on the open channel feature points. Based on the fitted curve and the unit width flow rate at the location of the feature point, the equilibrium water depth value of the feature point in the open channel is calculated to obtain the equilibrium water depth result of the open channel. The formula for the fitted curve is: in: For unit width flow, To balance the water depth.

2. The method for estimating the equilibrium water depth of an open intake and drainage channel in a power plant according to claim 1, characterized in that, The process of obtaining historical hydrological data of the waters where the power plant is located includes collecting the equilibrium water depth of each station, the average flow velocity of each station during spring tide, mid-tide, and neap tide; and obtaining the flow rate of each station's cross-section based on the equilibrium water depth and the average flow velocity.

3. The method for estimating the equilibrium water depth of an open intake and drainage channel in a power plant according to claim 1, characterized in that, The process of constructing the power flow model includes software selection, determination of the computational domain, mesh generation, determination of open boundaries, and model verification.

4. The method for estimating the equilibrium water depth of an open intake and drainage channel in a power plant according to claim 3, characterized in that, The mesh subdivision is used to fit detailed boundaries including complex headlands, estuaries, and breakwaters; The meshing process includes: locally densifying the model computation network in key engineering areas; using an unstructured triangular network to partition the computation domain to obtain the minimum spatial step size of the model mesh; and dividing the model network nodes for final computation based on the minimum spatial step size of the model mesh. The minimum spatial step size of the model mesh should ensure accurate differentiation of water intake and drainage channels.

5. The method for estimating the equilibrium water depth of an open intake and drainage channel in a power plant according to claim 1, characterized in that, When performing tidal current simulation calculations based on the aforementioned tidal current model, the process also includes determining the open boundary and specifying the tidal level or tidal volume of the open boundary. The process of determining the open boundary and giving the tidal level or tidal volume of the open boundary includes controlling the open sea tide at the open boundary using the tidal level process, calculating the tidal level boundary based on the tidal model, and adjusting it according to the measured flow velocity and direction.

6. The method for estimating the equilibrium water depth of an open intake and drainage channel in a power plant according to claim 1, characterized in that, The process of calculating the unit width flow rate at the feature point location based on the open channel feature points includes: simulating the water flow dynamics after the power plant is implemented based on a verified tidal flow model and extracting the average flow velocity and water depth at each feature point; and obtaining the flow rate in the open channel based on the average flow velocity and water depth.

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