Tidal current energy array field site selection method based on three-dimensional high-precision numerical model

Abstract

The invention relates to the field of ocean energy development and utilization, in particular to a tidal current energy array field site selection method based on a three-dimensional high-precision numerical model, which comprises the following steps: (1) a macroscopic site selection method; (2) a microscopic site selection method; (3) establishing a high-precision layered three-dimensional numerical model; (4) a tidal current energy resource refined evaluation method; analyzing a model calculation result, analyzing tidal current properties such as a large tide rising and falling moment, a small tide rising and falling moment, tidal current stability, energy flow density, theoretical reserve of tidal current energy resources, single-width energy flow flux and the like of a target sea area, and presenting an evaluation result through a visualization technology so as to guide a laying mode of a tidal current energy unit; compared with a traditional two-dimensional or simplified three-dimensional model, the evaluation precision is greatly improved. The tidal current characteristics at different water depths can be meticulously simulated, so that tidal current energy resource assessment is more comprehensive and accurate.

Description

Technical Field

[0001] The present invention relates to the field of marine energy development and utilization, and in particular to a tidal energy array site selection method based on a three-dimensional high-precision numerical model. Background Art

[0002] As a clean, renewable and stable energy resource, tidal energy has gradually become an important research object in the field of ocean energy development due to its abundant reserves and wide distribution. The utilization of tidal energy mainly relies on tidal energy generators to convert the kinetic energy of seawater into electrical energy, and the efficient and reasonable selection of the deployment location of tidal energy arrays plays a key role in improving energy capture efficiency and reducing costs. Therefore, the site selection method of tidal energy arrays has become a crucial technical link in the process of tidal energy development.

[0003] At present, most tidal energy site selection methods are based on two-dimensional numerical simulation or analysis of single tidal conditions, and fail to fully consider the complex three-dimensional flow field characteristics and their temporal and spatial changes in the tidal field. Traditional methods often lack accuracy in tidal resource assessment, especially in areas with complex terrain and changeable tidal currents. Existing technologies are difficult to accurately reflect the vertical changes and energy distribution of tidal currents. In addition, the impact of local terrain changes in the tidal field on the deployment of units is difficult to accurately simulate in traditional models. These deficiencies have restricted the accuracy and energy utilization of tidal energy unit deployment, limiting the efficient development and utilization of tidal energy.

[0004] In order to overcome the shortcomings of the prior art, there is an urgent need for a method for site selection of tidal energy arrays that can comprehensively consider the three-dimensional characteristics of the tidal field and high-precision stratification. The present invention is based on a three-dimensional high-precision numerical model, and through the combination of macroscopic site selection and microscopic site selection, a three-dimensional tidal numerical model that can truly reflect the distribution of tidal energy resources and their changing laws is constructed. By analyzing the rapid rise and fall moments of the high tide, the rapid rise and fall moments of the low tide, the tidal stability, the energy flow density, the theoretical reserves, the single-width energy flow and other parameters, the reserves and developability of tidal energy resources are carefully evaluated. Through this method, a rapid and accurate tidal energy resource assessment can be achieved, providing a reliable theoretical basis for the array deployment of tidal energy units, and promoting the sustainable development of ocean energy development. Summary of the invention

[0005] The purpose of the present invention is to provide a method for site selection of tidal energy array fields based on a three-dimensional high-precision numerical model, so as to solve the problems in the prior art such as insufficient accuracy of the model, difficulty in capturing vertical changes in the tidal field, and difficulty in optimizing the deployment of tidal energy units under complex terrain and changeable tidal conditions.

[0006] The technical solution adopted by the present invention is as follows:

[0007] A method for selecting a tidal energy array site based on a three-dimensional high-precision numerical model, the method comprising the following steps:

[0008] (1) Macro-site selection method: Based on historical tidal data, seabed topography data and macro-distribution of energy flux density, combined with geological survey results, the scope of sea areas suitable for tidal energy development is preliminarily determined at the macro level;

[0009] (2) Micro-site selection method: Based on the macro-site selection, the micro-site selection range of the array field is further accurately defined through local measurement and flow field analysis, taking into account the impact of factors such as terrain changes, tidal conditions and shoreline morphology on the deployment of tidal energy units. The local measurement and flow field analysis include calibrating the geographical coordinates of the sea area using a high-precision positioning system, measuring the water depth using sonar instruments, and monitoring the sea area flow velocity and direction using a current profiler.

[0010] (3) High-precision layered three-dimensional numerical model construction method: Based on the geographical location, water depth data and seabed topography data of the micro-site, a layered three-dimensional numerical model is constructed. The model includes unstructured grid generation, dynamic harmonic boundary condition setting, and tidal simulation. It is calibrated with measured and simulated data so that the model can accurately reflect the dynamic characteristics of the tidal current in the target sea area.

[0011] (4) Refined evaluation method of tidal energy resources: By analyzing the model calculation results, the tidal properties such as the time of rapid rise and fall of high tides, the time of rapid rise and fall of low tides, tidal stability, energy flow density, theoretical reserves of tidal energy resources, and single-width energy flow in the target sea area are analyzed, and the evaluation results are presented through visualization technology to guide the deployment of tidal energy units.

[0012] The macroscopic site selection method is implemented by the following steps:

[0013] a) Combine multi-source data, including ocean hydrology, geological exploration and remote sensing satellite data, to preliminarily determine the topographic contours and spatiotemporal distribution characteristics of tidal currents in the target sea area;

[0014] b) Conduct a multi-dimensional analysis of the interaction between tidal currents, waves, and wind currents in the target sea area, and select areas with larger flow velocity, higher energy flux density, and better stability as candidate array field locations.

[0015] The microscopic site selection method comprises:

[0016] a) Carry out geographic location calibration, water depth measurement, detailed seabed topography survey and real-time tidal field monitoring of candidate array field locations to generate detailed tidal level, flow velocity and flow direction distribution maps;

[0017] b) Combine actual data, analyze the tidal current characteristics of the sea area, and combine the seabed topography characteristics to determine the deployment area of ​​tidal energy units;

[0018] c) Use a multi-parameter evaluation model including terrain, flow velocity, environmental factors, etc., comprehensively consider eddy current effects, potential obstacles and construction feasibility, and select a suitable unit deployment location.

[0019] The high-precision layered three-dimensional numerical model construction method includes:

[0020] a) Use unstructured grid technology to construct a three-dimensional numerical model of the target sea area, and adopt a layered processing method to simulate the flow velocity changes of water bodies at different depths;

[0021] b) The model boundary conditions adopt the dynamic reconciliation method, combined with tidal current and large eddy simulation technology, to deal with complex tidal boundary problems, enhance the ability to capture tidal flow details, and achieve high-precision fitting of the coastline.

[0022] c) Compare the model results with the measured data and make optimal adjustments to ensure that the temporal and spatial accuracy of the model is within the error range allowed by the project.

[0023] The tidal energy resource refined assessment method includes:

[0024] a) Based on the output results of the three-dimensional model, the flow velocity and flow direction data of the complete tidal cycle in the target sea area are sorted out to determine the time when the spring tide rises and falls sharply and the time when the neap tide rises and falls sharply, and then the maximum potential of the tidal energy resources in the target sea area and the tidal characteristics when the energy flow density is low are determined;

[0025] b) Evaluate the stability of tidal currents in the area, including flow direction rotation and flow velocity asymmetry, using the following formula:

[0026] α θ =180°-|θ e -θ f |

[0027] α v =|1-v e / v f |

[0028] In the formula, α θ is the rotation of the tidal flow direction, θ f θ e are the main axis directions during high tide and low tide, α v is the symmetry of tidal flow velocity, v f and v e are the average flow velocities during high tide and low tide, respectively.

[0029] c) Based on the velocity data of the three-dimensional model, the average velocity data and the maximum velocity data of the target sea area in one cycle are sorted out, and then the average energy flux density and the maximum energy flux density of the tidal energy are calculated using the following formula:

[0030]

[0031] Where P m is the average energy flux density of a complete tidal cycle, ρ is the density of seawater, is the average tidal velocity of a complete tidal cycle, P smax is the maximum energy flux density of a complete power flow cycle, V smax is the maximum tidal velocity in a complete tidal cycle.

[0032] d) According to the above tidal energy resource reserve assessment method, multiple sections with relatively rich tidal energy resources are selected to calculate the theoretical tidal energy reserves passing through a specific waterway section within a period of time, using the following formula:

[0033]

[0034] Where P theoretical is the theoretical tidal energy reserve; t is the initial time; T is the evaluation period, usually one year; L is the width of the waterway; V is the velocity of the tidal current.

[0035] When evaluating the theoretical reserves of tidal energy in practice, we usually face the challenge of difficulty in obtaining continuous flow velocity data. Relatively speaking, it is easier to obtain discrete flow velocity data at a specific time and location. In order to adapt to this data availability situation, the Flux method is used to estimate the theoretical reserves of tidal energy. The formula is as follows:

[0036] P theoretical =P m ·A

[0037] Where A is the area of ​​the waterway cross section.

[0038] d) Since the target waters are deep and the waterway changes significantly with the depth, in order to fully evaluate the tidal energy resources of the waterway, the section with the largest theoretical reserve is selected to further evaluate the single-width energy flow, that is, the energy flow per unit width, using the following formula:

[0039]

[0040] Where P is the energy flow rate and h is the water depth.

[0041] However, since the flow velocity changes significantly with depth, the flow velocity can be regarded as a function of depth z, so the energy flow can be expressed as:

[0042]

[0043] The vertical distribution of tidal flow velocity generally presents the characteristics of exponential distribution, which is often expressed in the following exponential distribution forms:

[0044]

[0045] In the formula, v 0 is the surface velocity; α is the velocity profile variation coefficient, which can be calculated according to the specific sea area using the least squares method; C is the residual velocity of the tidal current; β is the correction coefficient, which is used to adjust the model to better match the actual situation.

[0046] Finally, the most suitable exponential distribution form is brought into the expression of single-width energy flux to obtain:

[0047]

[0048] In the formula, h 1 ,h 2 is the water depth between any two points (|h 1 |<|h 2 |),v exp (z) is the flow velocity at depth z, which is the most suitable exponential distribution form, P u is the single-width energy flow rate.

[0049] e) The assessment results of tidal energy resources are displayed through visualization technology, including key indicators such as tidal level, flow direction, flow velocity, flow direction stability, and energy flow density.

[0050] The unstructured grid generation technology uses triangular or tetrahedral grid units to improve the simulation accuracy of complex terrain in the calculation area, and improves the accuracy of key areas (such as coastal areas or areas with large seabed undulations) through grid encryption.

[0051] The eddy and turbulence analysis in the evaluation method adopts large eddy simulation technology, calculates the three-dimensional distribution of eddy and turbulence by refining the grid, and evaluates the scope and degree of their impact on the unit.

[0052] This method is particularly suitable for coastal waters with complex terrain and multiple interactions of tidal currents, waves, and wind currents. By fusing three-dimensional high-precision models with layered data, it can accurately reflect the spatial distribution characteristics of tidal energy and provide comprehensive decision-making support for the deployment of tidal energy units.

[0053] The innovation of the present invention lies in the use of a high-precision layered three-dimensional numerical model that can capture the flow velocity and energy flux density distribution at different water depths in detail. This layered model combines unstructured grid division with layered processing, so that the model can not only reflect the horizontal changes of the tide, but also accurately depict the dynamics of the tide in the vertical direction.

[0054] The innovation of this invention lies in proposing multi-dimensional tidal energy resource assessment parameters such as the rapid rise and fall of spring tides and neap tides, tidal stability, energy flow density, and single-width energy flow. These assessment parameters provide a detailed and comprehensive analysis of the tidal field, making the assessment results more scientific and accurate. Combined with visualization technology to display the assessment results, it provides clear guidance for the scientific deployment of tidal energy units.

[0055] Compared with the prior art, the present invention has the following outstanding and beneficial technical effects:

[0056] 1. The present invention adopts a high-precision layered three-dimensional numerical model, which can accurately capture the flow velocity changes of the tidal field in the vertical and horizontal directions, especially under complex terrain and variable tidal conditions. Compared with traditional two-dimensional or simplified three-dimensional models, the assessment accuracy is greatly improved. The model can simulate the tidal characteristics at different water depths in detail through unstructured grid division and layered processing, making the tidal energy resource assessment more comprehensive and accurate.

[0057] 2. The present invention combines the methods of macro-site selection and micro-site selection, from large-scale preliminary site selection to local precise site selection, providing a combination of global and local refinement. Macro-site selection quickly locks in high-quality sea areas for tidal energy development, while micro-site selection conducts in-depth analysis of local characteristics, avoiding the uncertainty of single-scale evaluation in existing technologies, and greatly improving the deployment efficiency and resource utilization of tidal energy units.

[0058] 3. The present invention proposes multiple evaluation dimensions, such as the rapid rise and fall of spring tides and neap tides, tidal stability, energy flow density, and single-width energy flow, to comprehensively analyze the complex characteristics of the tidal field and ensure the reliability of the tidal energy resource evaluation results. Compared with the relatively single evaluation method in the prior art, the present invention has significantly improved the evaluation dimension and depth, and the evaluation results are more scientific and accurate, providing a rich reference basis for the deployment of tidal energy array fields.

[0059] 4. The comprehensive evaluation process of the present invention realizes fast and efficient resource evaluation from macro to micro, significantly shortening the time of preliminary site selection for tidal energy development. Compared with the traditional method that relies on a large number of on-site measurements and evaluations, the present invention greatly improves the efficiency of resource evaluation through the automated evaluation of numerical models, providing strong support for the rapid advancement of the project. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 It is an overall flow chart of a tidal energy array site selection method based on a three-dimensional high-precision numerical model of the present invention.

[0061] Figure 2 It is a flow chart of macroscopic site selection of tidal energy array field of the present invention.

[0062] Figure 3It is a flow chart of microscopic site selection of tidal energy array field of the present invention.

[0063] Figure 4 It is a flow chart of the process of building a high-precision layered three-dimensional numerical model of the present invention.

[0064] Figure 5 It is a flow chart of the refined evaluation of tidal energy resources of the present invention.

[0065] Figure 6 This is the research area scope of the present invention.

[0066] Figure 7 This is the grid construction range of the research area of ​​the present invention.

[0067] Figure 8 This is the water depth distribution map of the entire Zhoushan sea area of ​​the present invention.

[0068] Fig. 9 This is the water depth distribution map of the study area of ​​the present invention.

[0069] Fig.10 This is a comparison chart of tide levels in the study area of ​​the present invention at different times.

[0070] Fig.11 It is the flow velocity and direction rose diagram of the study area of ​​the present invention.

[0071] Fig.12 It is the average energy flux density distribution diagram of the research area of ​​the present invention.

[0072] Fig.13 It is the maximum energy flux density distribution diagram of the research area of ​​the present invention.

[0073] Fig.14 Schematic diagram of four control surface selections for the study area of ​​the present invention.

[0074] Fig.15 It is a schematic diagram of the fitting process of the flow velocity along the depth direction at section C in the study area of ​​the present invention. DETAILED DESCRIPTION

[0075] like Figure 1-Figure 15As shown, the present invention provides a method for selecting a tidal energy array field site based on a three-dimensional high-precision numerical model, which can quickly and accurately select a suitable tidal energy array field and provide a reliable theoretical basis for the array deployment of tidal energy units. The method includes macroscopic site selection, microscopic site selection, high-precision layered three-dimensional numerical model construction and refined evaluation of tidal energy resources; the macroscopic site selection of tidal energy array field is to select a sea area with relatively rich tidal energy resources and relatively flat seabed terrain from a large area of ​​sea area based on existing survey data; the microscopic site selection of tidal energy array field is based on the selection of the macroscopic site, and then conducts water depth measurement and flow field analysis on a small area of ​​sea area to conduct The microscopic target sea area of ​​the array field is accurately delineated in one step; the construction of a high-precision layered three-dimensional numerical model is to comprehensively consider the geographical information, water depth data and seabed topography data of the target sea area that have been determined in the early stage, construct a layered three-dimensional numerical model of the target sea area, and calibrate the model so that the model can accurately reflect the dynamic characteristics of the tides in the target sea area; the refined assessment of tidal energy resources is to analyze the tidal characteristic parameters of the target sea area, including the moments of rapid rise and fall of high tides, the moments of rapid rise and fall of low tides, tidal stability, energy flow density, theoretical reserves of tidal energy resources, single-width energy flow, etc., and then present the assessment results through visualization technology to guide the deployment of tidal energy units.

[0076] The study area of ​​this embodiment is a waterway between Zhaizhuoshan Island and Xiaozhaizhuoshan Island in Zhoushan City, with geographical coordinates of 122°074'~122°078' east longitude and 29°955'~29°96' north latitude. As there are many islands in the Zhoushan waters and the seabed terrain is complex and changeable, in order to reduce the impact of the small model boundary and better reflect the tidal characteristics of the study area, the simulation range is expanded to the entire Zhoushan waters, with geographical coordinates of 29°955'~29°96' east longitude and 29°955'~29°96' north latitude. The study area is as follows Figure 6 shown.

[0077] The specific method for selecting the macro site of the tidal energy array field is as follows:

[0078] First, a preliminary assessment of the target sea area is conducted based on multi-source data such as ocean hydrology, geological exploration and remote sensing satellites. Ocean hydrological data include tide level, flow velocity, flow direction, tidal cycle and spatiotemporal distribution characteristics of tidal currents. These data can be obtained through long-term field monitoring, ocean data platforms and remote sensing data. Geological exploration data is mainly used to reflect the topographic contours of the target sea area, especially parameters such as the topographic undulations and sediment thickness of the seabed. Geological exploration data comes from sonar mapping, depth detection and marine geological survey reports, which can reflect the complexity and local changes of the seabed topography in detail. Remote sensing satellite data provides a global perspective on sea surface changes and can assist in analyzing the dynamic characteristics of tidal currents in near-coastal areas. Through data fusion processing, the basic flow field characteristics of the tidal currents in the target sea area and an accurate description of the seabed topography can be obtained.

[0079] On this basis, the temporal and spatial distribution characteristics of tidal currents in the target sea area are analyzed. Using tidal current observation data, the spatial distribution of tidal current velocity in the sea area is preliminarily evaluated, especially the seasonal changes in tidal current velocity and the periodic changes in tidal current direction. Through the time series analysis of the tidal current, the areas with large and relatively stable current velocity are determined, and the candidate areas suitable for tidal current energy development are preliminarily screened out. In addition, based on the long-term observation data of tidal current velocity, the energy flow density of the area is calculated to evaluate the theoretical reserves of tidal current energy resources. Generally speaking, areas with higher energy flow density often have higher development value, so energy flow density is one of the extremely important evaluation parameters in the micro-field selection process.

[0080] Secondly, within the initially determined target sea area, a multi-dimensional analysis of the interaction between tidal currents, waves and wind currents is conducted. Tidal currents are the main source of energy, but the coupling of waves and wind currents may disturb the tidal current field, especially in shallow waters and coastal areas, where the impact of waves on tidal currents is particularly significant. Through numerical simulation, a detailed evaluation of the impact of waves and wind currents on tidal currents in different seasons and under different meteorological conditions is conducted, especially analyzing the degree of disturbance of waves and wind currents on tidal current velocity and direction. With the assistance of the large eddy simulation model, the local impact of eddies and turbulence on the flow field is further studied to ensure that the selected candidate area not only has a large flow velocity, but also a stable energy flow density, which is suitable for the deployment of tidal energy units.

[0081] After the multi-dimensional analysis is completed, the areas that meet the following conditions are finally selected as candidate tidal energy array fields: high flow velocity, high energy flow density, good tidal stability, less eddy and turbulent influence, flat seabed terrain, and suitable for the deployment and construction of tidal energy units. In this process, special attention should be paid to the long-term stability of tidal energy development to ensure that the energy output variation range of tidal energy resources during high tide and low tide is controllable, and the long-term operation safety of the equipment should be considered.

[0082] The specific method for selecting the microscopic site of the tidal energy array field is as follows:

[0083] First, for the candidate array field area, carry out detailed geographic location calibration, water depth measurement, seabed topography survey and real-time monitoring of tidal field. At this stage, use high-precision satellite positioning system (such as DGPS) to geo-calibrate the target sea area to ensure the accuracy of the selected area and the rationality of spatial layout. At the same time, use multi-beam sonar depth sounder to accurately measure the water depth of the target sea area and generate a water depth profile. This step is particularly important because the installation of tidal energy units needs to fully consider the water depth to ensure that the units can maintain normal operation under different tidal conditions. Next, implement a detailed survey of the seabed topography, use side-scan sonar and geological detection instruments to scan the seabed, and record the ups and downs of the seabed, sediment distribution and the existence of seabed obstacles in detail. The seabed survey is not only used to confirm the foundation stability when the unit is deployed, but also to provide key data for subsequent construction. In terms of tidal field monitoring, a Doppler acoustic current profiler is used to monitor the tidal velocity and direction in the area in real time, record the changes in tide level, velocity and direction at different tidal stages, and generate a refined tidal field distribution map. These data can help further analyze the distribution and stability of tidal energy resources.

[0084] After completing the above data collection, the tidal characteristics analysis stage begins. This stage requires combining the monitoring data of tidal level, velocity and direction to analyze the tidal change characteristics of the target sea area, especially the velocity characteristics during high tide and low tide and the periodic fluctuations of the tidal current. At the same time, based on the survey data of the seabed topography, the interaction between the seabed topography and the tidal current is deeply analyzed. The undulation of the seabed may cause the local tidal current velocity to increase or decrease, thereby affecting the power generation efficiency of the unit. Therefore, the disturbance effect of the seabed topography on the tidal current velocity and direction must be evaluated in detail. Through the detailed analysis of the tidal flow field, the preliminary areas for the deployment of tidal energy units are determined. These areas must have high and stable tidal current velocities, suitable water depths and stable seabed topography, laying the foundation for subsequent evaluations.

[0085] Next, a multi-parameter comprehensive evaluation model is used to conduct an in-depth evaluation of the determined tidal energy unit deployment location. The model combines multiple key factors such as seabed terrain characteristics, eddy effects, potential obstacles and construction feasibility for comprehensive analysis. First, the seabed terrain characteristics are analyzed, including the effects of seabed undulations on tidal flow velocity, seabed slope, and local terrain on turbulence formation. The height difference of the seabed will cause changes in the local tidal velocity, especially when there are obvious highlands or gullies on the seabed, the tide will accelerate or decelerate in these areas, forming local high or low velocity areas. This phenomenon may cause the tidal energy unit to fail to fully utilize the tidal energy in some locations, or cause structural fatigue risks due to excessive local flow velocity. If there is a large slope change in the seabed, it may cause the tidal direction to deflect, especially in areas where the water depth changes dramatically, the tidal current may change greatly with the seabed slope. This will not only affect the capture efficiency of the tidal energy unit, but may also cause uneven force when the unit is installed, affecting the structural stability. The complexity of the seabed terrain may also cause eddies in the tidal field, especially in areas where the seabed terrain changes suddenly (such as submarine mountains, gullies or seabed uplifts). These eddies will cause energy loss downstream of the unit and weaken the power generation efficiency of subsequent units. In addition, pressure fluctuations and unstable flows in the eddy area will cause additional stress on the structure of the unit, so these areas must be avoided. Then, the impact of the eddy effect on the deployment of the unit is evaluated, especially when multiple units are deployed in an array, the mutual interference between the units will form eddies, which will weaken the power generation efficiency of the downstream units. By introducing large eddy simulation technology, the eddy distribution and its influence range are analyzed in detail, the unit deployment position is optimized, and the efficiency of each unit in the array is maximized. Secondly, potential seabed obstacles such as shipwrecks, rocks, and sediment protrusions are checked to ensure the safety and stability of the unit deployment. On this basis, the construction feasibility of the deployment area is analyzed, including the bearing capacity of the seabed, the complexity of the geological structure, and the installation and maintenance conditions of the construction equipment, to ensure that the unit can be safely and stably deployed and operated for a long time.

[0086] The specific method for constructing the high-precision layered three-dimensional numerical model of tidal energy is as follows:

[0087] First, according to the target sea area of ​​micro-site selection, the geographical coordinate information and water depth point data of the sea area are sorted out, and a one-to-one correspondence is established between the two, that is, each geographical coordinate information point has a corresponding water depth point, and then the Kriging interpolation method is used to calculate the water depth distribution of the target sea area, and its formula can be expressed as follows:

[0088]

[0089] In the formula, C(x i -x j ) represents the covariance function; λ irepresents weight; μ is the Lagrange multiplier, which is used to ensure that the sum of weights is equal to 1. The water depth data of Zhoushan waters mainly come from paper charts numbered 13300, 13310, 13359, 13361, 13391 and 13519 published by the China Maritime Safety Administration.

[0090] like Figure 8 As shown in FIG. 1 , this embodiment draws a water depth distribution map of the entire Zhoushan sea area based on the interpolation results. Fig. 9 As shown, in order to better understand the water depth and seabed topography of the Zhaizhuoshan waterway, the water depth data of the study area were further extracted, and a more detailed three-dimensional water depth map was drawn using these data. The slope of the study area shows significant spatial variation, and its water depth distribution is characterized by deeper water at the east and west ends and shallower water in the middle. Specifically, the water depth on the west side is deeper than that on the east side. In the western region, the slope is steeper and the water depth changes rapidly, with the deepest reaching about 55 meters. In contrast, the slope in the central and eastern regions is relatively gentle, and the water depth is usually maintained between 20 and 25 meters.

[0091] Secondly, the model is constructed using unstructured grid technology. In order to adapt to the complex terrain and tidal characteristics of the target sea area, unstructured grids are used in the model for three-dimensional numerical simulation. This technology can achieve high-precision terrain fitting and detailed tidal field characterization through flexible grid division, especially near the coastline and in areas with large seabed undulations. In the process of model construction, detailed data on water depth, coastline and terrain of the target sea area are first collected. Based on these data, the grid density is locally encrypted according to the complexity of the terrain, especially in areas such as coastlines, islands, and shoals, in order to improve the simulation accuracy of these key areas. In order to further improve the vertical analysis accuracy of the model, the model uses layered processing technology to divide the water body into multiple water layers, and set different flow velocity change areas from the surface to the seabed according to the change of water depth. This layered processing method can effectively capture the change of flow velocity gradient in the vertical direction of the tidal current, especially at the junction of deep water and shallow water areas. The model can accurately simulate the subtle changes in the tidal field and ensure the accurate evaluation of the distribution of tidal energy resources. Based on the above construction of unstructured grids, stratified processing of water bodies and refined division of coastlines, a stratified numerical model based on the target sea area can be built.

[0092] Then, in terms of boundary condition setting, the present invention adopts a dynamic reconciliation method to ensure that the complex boundary problems of the tidal field in the simulation process can be effectively handled. The boundary conditions simulate the periodic changes of the tidal current by combining the main tidal components of the tidal current. These tidal components are input into the model after precise reconciliation analysis, providing a basis for the dynamic changes of the boundary conditions of the tidal current field. In order to further improve the simulation accuracy, the large eddy simulation technology is used to refine the turbulence and eddy in the tidal current field. Large eddy simulation can capture the transient changes of large-scale turbulence in the tidal current field, especially the local eddy area formed when the tidal current flows through complex terrain or encounters submarine obstacles. Through this technology, the model can accurately simulate the influence of eddies on the distribution of tidal energy resources, ensuring that the tidal energy resource assessment under complex boundary conditions has high accuracy. Based on the above, through the dynamic reconciliation analysis of the tidal boundary, the input of the tidal component, and the fine processing of turbulence and eddy using large eddy simulation, a high-precision layered three-dimensional numerical model based on the target sea area is built.

[0093] After the model is built, the simulation results are compared with the measured data and the error analysis is performed to ensure that the accuracy of the model meets the engineering requirements. At this stage, several key parameters such as tidal level, flow velocity, and flow direction are selected for verification. The measured data mainly come from the on-site tidal observation system (such as ADCP) and historical data. Multiple statistical error analysis indicators are introduced, including mean absolute error, mean relative error, root mean square error, correlation coefficient, and technical score. By comparing the simulation results and measured data of different time periods, the temporal and spatial error distribution of the model is determined, the error source is analyzed, and optimization adjustments are made.

[0094] To ensure the accuracy of the hydrodynamic model used in this study, the model was calibrated using observation data from station 1, which is located at Figure 6 As shown in the figure. During the calibration of the model, special attention was paid to two key parameters: bed resistance and eddy viscosity. Bed resistance directly affects the degree of flow velocity reduction in the model, while eddy viscosity affects the turbulent characteristics and mixing effect of the fluid. By repeatedly adjusting key parameters such as bed resistance and eddy viscosity, the difference between the model simulation values ​​(tide level, flow velocity and flow direction) and the measured values ​​can be minimized.

[0095] Fig.10 The comparison between the tidal level simulation results obtained by the three-dimensional model and the measured results during high tide, medium tide and low tide is shown. It can be seen that the simulation results of the model in amplitude and phase show good consistency with the measured results.

[0096] If the error exceeds the allowable range of the project, the optimization algorithm is used to adjust the initial conditions, boundary conditions and grid density of the model until the error is controlled within the requirements of the engineering design. In the process of optimization and adjustment, special attention is paid to the changes in tidal velocity under different tidal conditions and the disturbance effect of eddies on the tidal field to ensure the prediction accuracy of the model at different time scales and spatial scales. Finally, a high-precision layered three-dimensional numerical model that meets the tidal characteristics of the target sea area is obtained.

[0097] Average relative error:

[0098] Average relative error:

[0099] Root Mean Square Error:

[0100] Correlation coefficient:

[0101]

[0102] In the formula, mod is the simulated value, obs is the observed value, N is the time series, is the average value of the simulation value, is the average value of the observed value. The closer the average relative error, average absolute error, and root mean square error are to 0, the better the model calculation effect is; the closer the correlation coefficient and technical score are to 1, the closer the simulated calculation value is to the observed value.

[0103] The accuracy of the model's tide level was evaluated using five statistical indicators: average relative error, average absolute error, root mean square error, correlation coefficient, and technical score. The calculation results are shown in Table 1. From the data in the table, it can be seen that the model-simulated tide level is highly consistent with the measured results, the error level is low, and the correlation is significant.

[0104] Table 1 Calculation results of tide level statistical indicators

[0105]

[0106] The specific method for the refined assessment of tidal energy resources is as follows:

[0107] First, based on the output results of the three-dimensional numerical model, the system organizes the flow velocity and flow direction data within a complete tidal cycle in the target sea area. The three-dimensional numerical model can output tidal fields in different time periods, including the spatiotemporal changes of flow velocity and flow direction. Through these data, the changes in tidal flow direction are analyzed, and then the rising and falling moments during spring tides and neap tides are determined. During spring tides, the changes in flow velocity and flow direction are more drastic, usually manifested as higher flow velocity and rapid adjustment of tidal direction. These time periods represent the maximum potential moments of tidal energy resources. By accurately analyzing the time nodes of rising and falling, the peak value of tidal energy resources can be determined; during neap tides, the flow velocity and flow direction change more slowly, and the flow velocity is lower, which represents a period of low energy flow density, which is crucial for the selection of tidal energy units. When analyzing the changes in flow velocity during spring tides and neap tides, it is necessary not only to pay attention to the extreme points of the tidal current, but also to consider the duration and frequency of tidal changes, so as to more comprehensively evaluate the spatiotemporal distribution characteristics of tidal energy resources.

[0108] Next, evaluate the tidal stability in the area. The stability of the tidal current directly affects the power generation efficiency of the unit and the reliability of equipment operation, especially in sea areas with obvious asymmetry of flow velocity and significant rotation of flow direction, which will interfere with the tidal current energy capture effect.

[0109] This embodiment extracts the flow velocity and flow direction data of station 1 from the model, and draws a rose diagram of the flow velocity and flow direction of the station, as shown in FIG. Fig.11 As shown. During high tide, the velocity distribution extends to the two extremes, exceeding 2 m / s in some areas, indicating that intermittent strong currents may exist in the area. During mid-tide, the velocity changes slightly, the overall velocity slows down, and no particularly high or low velocity is observed. During low tide, the velocity is mainly concentrated around 1 m / s, with a small range of variation, indicating that during low tide, the velocity in the area is relatively stable and the flow direction is relatively consistent. Overall, the velocity and direction of the study area remain relatively stable.

[0110] In order to accurately quantify the stability of the tidal current, the present invention uses two indicators, flow velocity asymmetry and flow direction rotation, to evaluate the tidal current stability. The formula is as follows:

[0111] α θ =180°-|θ e -θ f |

[0112] α v =|1-v e / v f |

[0113] In the formula, α θ is the rotation of the tidal flow direction, θ f is the main axis direction during high tide, θ eis the main axis direction during low tide, α v is the symmetry of tidal flow velocity, v f is the average velocity during the period of tension, v e is the average flow velocity during low tide. This formula can effectively evaluate the flow rotation (i.e. the degree of flow deflection) and the asymmetry of flow velocity (i.e. the difference in flow velocity between high tide and low tide) by analyzing the time series of flow velocity and flow direction. When the tidal flow direction deflects greatly or the flow velocity asymmetry is significant, the energy capture efficiency of the unit may be affected. Therefore, the tidal stability assessment is crucial for optimizing the unit deployment location. By calculating the tidal stability index in different time periods, areas suitable for long-term stable power generation can be identified. Table 2 below shows the calculation results of the tidal stability in the study area.

[0114] Table 2 Calculation results of power flow characteristics

[0115] Power flow characteristic parameters Numeric Tidal current energy characteristic parameters Numeric Average flow rate (m / s) 1.51 Maximum flow rate (m / s) 3.83 Average flow channel depth (m) 21.15 Maximum channel depth (m) 35.44 Average flow velocity during high tide (m / s) 1.83 Average current velocity during low tide (m / s) 1.37 Main axis direction during high tide (°) 243.7 Main axis direction during low tide (°) 66.9 Standard deviation of flow direction during high tide (°) 2.93 Standard deviation of flow direction during low and high tides (°) 5.16 Symmetry of flow rate 0.2514 Rotation of flow direction (°) 3.3

[0116] After completing the tidal stability assessment, the average and maximum flow velocity data in the complete tidal cycle in the target sea area are sorted out based on the flow velocity data of the three-dimensional model. The average flow velocity reflects the stable output level of tidal energy in the entire tidal cycle, while the maximum flow velocity represents the extreme state that the tidal current may reach in a certain period of time. Based on these flow velocity data, the average energy flux density and maximum energy flux density of tidal energy are further calculated using the following formula:

[0117]

[0118] Where P m is the average energy flux density of a complete tidal cycle, ρ is the density of seawater, is the average tidal velocity of a complete tidal cycle, P smax is the maximum energy flux density of a complete power flow cycle, V smax is the maximum speed of the tidal current in a complete tidal cycle. These two formulas can be used to calculate the energy output potential of tidal energy at different flow rates, especially under the condition of maximum flow rate, and the peak energy flux density of tidal energy resources can be evaluated. The average energy flux density represents the long-term stable output capacity of tidal energy resources, which is of great significance for the economic evaluation of the unit. By extracting the flow velocity data of the study area, it is found that the area with a flow velocity exceeding 2.2m / is relatively wide, especially in the eastern waterway, where the flow velocity is significantly higher than that in the west. Calculate the average energy flux density P of the entire study area m , and drew Fig.12 The average energy flux density distribution diagram. The average energy flux density of the waterway is between 0.4kW / m 2 Up to 2.8kW / m 2The maximum energy flux density in the study area is calculated and the results are plotted as Fig.13 The peak energy flux density distribution diagram is shown. It can be seen from the figure that the maximum energy flux density in most areas has reached 3.2kW / m 2 This high value area is quite wide.

[0119] Next, based on the evaluation method of tidal energy resource reserves, multiple sections with relatively rich tidal energy resources are selected from the target sea area, and the theoretical reserves of tidal energy in these sections are further calculated. The formula is as follows:

[0120]

[0121] Where P theoretical is the theoretical tidal energy reserve; t is the initial time; T is the evaluation period, usually one year; L is the width of the waterway; V is the velocity of the tidal current.

[0122] In actual engineering, it is often challenging to obtain continuous tidal flow velocity data, while discrete flow velocity data at a specific time and location is usually easier to obtain. In order to overcome this problem, the present invention uses the Flux method to process discrete flow velocity data and then estimate the theoretical reserves of tidal energy. The calculation formula of the Flux method is as follows:

[0123] P theoretical =P m ·A

[0124] Where A is the area of ​​the waterway cross section.

[0125] Through the Flux method, discrete flow velocity data can be effectively integrated to calculate the tidal energy resource reserves at different sections, ensuring that the tidal energy potential can still be accurately estimated when data is scarce.

[0126] like Fig.14 As shown in Figure 3, when evaluating the tidal energy resource reserves of the waterways in the study area, the spatial distribution of water depth and average energy flux density was comprehensively considered, and four key control surfaces were determined accordingly. In the process of selecting the control surface, intersections with the southern and northern coastlines were deliberately avoided. The main reason for this choice is that the seabed topography in this area is complex and the slope is large, which makes it difficult to install and maintain the equipment, and may also affect the long-term operating efficiency and safety of the equipment. Therefore, it is not suitable for the deployment of tidal energy units. In order to further evaluate the tidal energy potential of the selected control surface, the main characteristic parameters on the control surface were calculated in detail, including cross-sectional water depth, cross-sectional length, cross-sectional area and theoretical tidal resources. The calculation results are shown in Table 3.

[0127] Table 3 Calculation results of cross-section characteristic parameters

[0128]

[0129] In the study area, Fig.14 The theoretical tidal energy reserves of the four sections A, B, C and D in the waterway range from 2.4MW to 9.98MW. This change reflects the trend that the tidal energy resources gradually increase from the west to the east of the waterway, reach a peak, and then gradually decrease, showing a significant change in the amount of resources.

[0130] Since the target water area is deep and the topography of the waterway changes significantly with the water depth, in order to fully evaluate the tidal energy resources in the waterway, the present invention further selects the section with the largest theoretical reserve and calculates the energy flow per unit width (single-width energy flow). This index reflects the energy flow density passing through the section per unit width and is calculated using the following formula:

[0131]

[0132] Where P is the energy flow rate and h is the water depth.

[0133] However, since the tidal velocity varies greatly with water depth, the velocity distribution can usually be regarded as a function of water depth. In actual tidal fields, the vertical distribution of velocity usually presents exponential distribution characteristics, and the commonly used expression is:

[0134]

[0135] In the formula, v 0 is the surface velocity; α is the velocity profile variation coefficient, which can be calculated based on the specific sea area using the least squares method; C is the residual velocity of the tidal current; β is the correction coefficient, which is used to adjust the model to better match the actual situation. Fig.15 As shown in the figure, the actual flow rate data is brought into nonlinear fitting, and the correlation coefficient (R 2 ) measures the fitting effect of the exponential distribution. The correlation coefficient R of the quadratic exponential distribution 2 It is 0.98, which is closest to 1, indicating that the exponential distribution fits the measured data very well, indicating that the actual situation of flow velocity changing with water depth can be accurately described by the model.

[0136] By bringing the exponential distribution of flow velocity into the calculation formula of single-width energy flow, a more accurate distribution characteristic of tidal energy resources in the section can be obtained. The calculation formula is as follows:

[0137]

[0138] In the formula, h 1 ,h 2 is the water depth between any two points (|h 1 |<|h 2|),v exp (z) is the flow velocity at depth z, which is the most suitable exponential distribution form, P u This method can effectively capture the nonlinear characteristics of flow velocity changing with water depth and ensure the accuracy of energy flow calculation.

[0139] Finally, the evaluation results of tidal energy resources are displayed through visualization technology. The visualization results include key indicators such as tidal level changes, velocity distribution, flow direction distribution, energy flow density, and tidal stability. These results can present the spatial distribution of tidal energy resources in the target sea area in an intuitive way, providing a key reference for decision-making on tidal energy development. Through these visualization results, engineers can understand the tidal energy potential and stability in different regions, thereby optimizing the deployment plan of the units and ensuring efficient use of resources.

[0140] The innovation of the present invention lies in the use of a high-precision layered three-dimensional numerical model that can capture the flow velocity and energy flux density distribution at different water depths in detail. This layered model combines unstructured grid division with layered processing, so that the model can not only reflect the horizontal changes of the tide, but also accurately depict the dynamics of the tide in the vertical direction.

[0141] The innovation of this invention lies in proposing multi-dimensional tidal energy resource assessment parameters such as the rapid rise and fall of spring tides and neap tides, tidal stability, energy flow density, and single-width energy flow. These assessment parameters provide a detailed and comprehensive analysis of the tidal field, making the assessment results more scientific and accurate. Combined with visualization technology to display the assessment results, it provides clear guidance for the scientific deployment of tidal energy units.

[0142] The above embodiments are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the protection scope of the present invention.

[0143] The above shows and describes the basic principle and main features of the technical solution and the advantages of the technical solution. The technicians in this industry should understand that the technical solution is not limited by the above embodiments, and the above embodiments and descriptions are only for explaining the principle of the technical solution. Without departing from the spirit and scope of the technical solution, the technical solution will have various changes and improvements, and these changes and improvements fall within the scope of the technical solution to be protected.

Claims

1. A method for site selection of tidal energy array field based on three-dimensional high-precision numerical model, characterized in that: The method comprises the following steps: (1) Macro-site selection method: Based on historical tidal data, seabed topography data and macro-distribution of energy flux density, combined with geological survey results, the scope of sea areas suitable for tidal energy development is preliminarily determined at the macro level; (2) Micro-site selection method: Based on the macro-site selection, the micro-site selection range of the array field is further accurately defined through local measurement and flow field analysis, taking into account the impact of factors such as terrain changes, tidal conditions and shoreline morphology on the deployment of tidal energy units. The local measurement and flow field analysis include calibrating the geographical coordinates of the sea area using a high-precision positioning system, measuring the water depth using sonar instruments, and monitoring the sea area flow velocity and direction using a current profiler. (3) High-precision layered three-dimensional numerical model construction method: Based on the geographical location, water depth data and seabed topography data of the micro-site selection range, a layered three-dimensional numerical model is constructed. The model includes unstructured grid generation, dynamic harmonic boundary condition setting, and tidal simulation. It is calibrated with measured and simulated data so that the model can accurately reflect the dynamic characteristics of the tidal current in the target sea area. (4) Refined evaluation method of tidal energy resources: By analyzing the model calculation results, the tidal properties such as the time of rapid rise and fall of high tides, the time of rapid rise and fall of low tides, tidal stability, energy flow density, theoretical reserves of tidal energy resources, and single-width energy flow in the target sea area are analyzed, and the evaluation results are presented through visualization technology to guide the deployment of tidal energy units.

2. The method for selecting a site for a tidal energy array field according to claim 1, characterized in that: The macroscopic site selection method is implemented by the following steps: a) Combine multi-source data, including ocean hydrology, geological exploration and remote sensing satellite data, to preliminarily determine the topographic contours and spatiotemporal distribution characteristics of tidal currents in the target sea area; b) Conduct a multi-dimensional analysis of the interaction between tidal currents, waves, and wind currents in the target sea area, and select areas with larger flow velocity, higher energy flux density, and better stability as candidate array field locations.

3. The method for selecting a site for a tidal energy array field according to claim 1, characterized in that: The microscopic site selection method comprises: a) Carry out geographic location calibration, water depth measurement, detailed seabed topography survey and real-time tidal field monitoring of candidate array field locations to generate detailed tidal level, flow velocity and flow direction distribution maps; b) Combine actual data, analyze the tidal current characteristics of the sea area, and combine the seabed topography characteristics to determine the deployment area of ​​tidal energy units; c) Use parameter evaluation models of terrain, flow velocity, and environmental factors, combined with eddy current effects, potential obstacles, and construction feasibility to select a suitable unit placement location.

4. The method for selecting a site for a tidal energy array field according to claim 1, characterized in that: The high-precision layered three-dimensional numerical model construction method includes: a) Use unstructured grid technology to construct a three-dimensional numerical model of the target sea area, and adopt a layered processing method to simulate the flow velocity changes of water bodies at different depths; b) The model boundary conditions adopt the dynamic reconciliation method, combined with tidal current analysis and large eddy simulation technology, to deal with complex tidal boundary problems, enhance the ability to capture tidal flow details, and achieve high-precision fitting of the coastline; c) Compare the model results with the measured data and make optimal adjustments to ensure that the temporal and spatial accuracy of the model is within the error range allowed by the project.

5. The method for selecting a site for a tidal energy array field according to claim 1, characterized in that: The tidal energy resource refined assessment method includes: a) Based on the output results of the three-dimensional model, the velocity and direction data of the complete tidal cycle in the target sea area are sorted out to determine the time when the spring tide rises and falls sharply and the time when the neap tide rises and falls sharply, and then the maximum potential of the tidal energy resources in the target sea area and the tidal characteristics when the energy flow density is low are determined; b) Evaluate the stability of tidal currents in the area, including flow direction rotation and flow velocity asymmetry, using the following formula: a θ =180°-|θ e -θ f α v =|1-v e / v f | In the formula, α θ is the rotation of the tidal flow direction, θ f is the main axis direction during high tide, θ e is the main axis direction during low tide, α v is the symmetry of tidal flow velocity, v f is the average flow velocity during high tide, v e is the average flow velocity during low tide. c) Based on the velocity data of the three-dimensional model, the average velocity data and the maximum velocity data of the target sea area in one cycle are sorted out, and then the average energy flux density and the maximum energy flux density of the tidal energy are calculated using the following formula: Where P m is the average energy flux density of a complete tidal cycle, ρ is the density of seawater, is the average tidal velocity of a complete tidal cycle, P smax is the maximum energy flux density of a complete power flow cycle, V smax is the maximum tidal velocity of a complete tidal cycle; d) According to the above tidal energy resource reserve assessment method, multiple sections with relatively rich tidal energy resources are selected to calculate the theoretical tidal energy reserves passing through a specific waterway section within a period of time, using the following formula: Where P theoretical is the theoretical reserve of tidal energy; t is the initial time; T is the evaluation period, usually one year; L is the width of the waterway; V is the velocity of the tidal current; The Flux method is used to estimate the theoretical reserves of tidal energy. The formula is as follows: P theoretical =P m ·A Where A is the area of ​​the waterway cross section. d) Select the section with the largest theoretical reserve of the waterway and evaluate the energy flow per unit width; the energy flow per unit width is the energy flow per unit width, using the following formula: Where P is the energy flow; h is the water depth; Considering the flow velocity as a function of depth z, the energy flux can be expressed as: The vertical distribution of tidal flow velocity generally presents the characteristics of exponential distribution, which is often expressed in the following exponential distribution forms: Where v0 is the surface velocity; α is the velocity profile variation coefficient, which is calculated based on the specific sea area using the least squares method; C is the residual velocity of the tidal current; β is the correction coefficient, which is used to adjust the model to better match the actual situation; Finally, the most suitable exponential distribution form is brought into the expression of single-width energy flux to obtain: Where h1 and h2 are the water depths at any two points (|h1|<|h2|), v exp (z) is the flow velocity at depth z, which is the most suitable exponential distribution form, P u is the single-width energy flow; e) The evaluation results of tidal energy resources are displayed through visualization technology, including key indicators of tidal level, flow velocity, flow direction, flow direction stability, and energy flow density.

6. The method for selecting a site for a tidal energy array field according to claim 4, characterized in that: The unstructured grid generation technology uses triangular or tetrahedral grid units to improve the simulation accuracy of complex terrain in the calculation area, and improves the accuracy of key areas through grid encryption processing.

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