Full-process iterative hybrid test method for offshore floating wind turbines

Abstract

The present invention discloses a full-process iterative hybrid test method for an offshore floating wind turbine. The offshore floating wind turbine is divided into two substructures, an upper wind turbine and a lower floating body. A full-time wind tunnel test is performed on the upper wind turbine substructure, and a full-time wave and current tank test is performed on the lower floating body substructure. Physical or numerical tests are performed on each of the full-time courses, and a full-time iteration method is used instead of a single iteration to avoid the time step competition problem. The method can accurately simulate the dynamic response of the wind turbine in a complex marine environment while maintaining the controllability of the test equipment and site.

Description

Technical Field

[0001] The present invention relates to the technical field of offshore floating wind power generation, and in particular to a full-process iterative hybrid test method for an offshore floating wind turbine. Background Art

[0002] Offshore wind turbines are categorized as fixed or floating based on their foundation type. As water depths continue to increase, traditional fixed offshore wind turbines are no longer able to meet the requirements of deep-sea wind energy development. It is currently widely recognized internationally that when operating water depths exceed 50 meters, the use of floating offshore wind turbine foundations and mooring systems offers greater economic benefits and broader market prospects.

[0003] However, the dynamic response of floating wind turbines is complex and is affected by a variety of environmental factors such as wind, waves, and currents. Their stability and reliability are directly related to the safety and economic benefits of offshore wind farms. At present, the test methods for offshore floating wind turbines are mainly divided into local tests and overall tests. Local test methods only test a certain part or substructure of the floating wind turbine, such as the wind turbine tower or the floating body. Although this type of test can conduct in-depth analysis of a specific component, it cannot consider the global response of the entire system, especially under the coupling of multiple physical fields such as wind, waves and currents. The results of local tests are difficult to fully reflect the overall dynamic behavior of the floating wind turbine.

[0004] Overall tests include two categories: whole-structure tests and hybrid substructure tests. Whole-structure tests are tests conducted on full-scale or scaled models of floating wind turbines to simulate the dynamic response of the entire wind turbine and its environmental conditions. Although whole-structure tests can capture the dynamic response characteristics of the entire system, they are limited by the scale of the test equipment, especially in complex marine environments, making it difficult to accurately simulate large-scale wind turbines. Scaled tests are also prone to introducing deviations from similarity theory, resulting in distorted test results. Hybrid substructure tests divide the entire system into multiple subsystems, each of which is tested or simulated separately, and the dynamic response of the entire system is solved through data interaction and iterative calculations. The main difficulty of this method is that it is difficult to ensure that the calculation time step is less than the load loading time step in the physical test, that is, there is a time step competition problem. It is necessary to ensure that the dynamic numerical simulation is completed before two adjacent loads are applied. This is often difficult to achieve for large and complex structures or complex load conditions. For example, offshore floating wind turbines are subject to complex conditions such as wind, waves, and currents, which makes hybrid tests difficult to carry out. Overall, the whole-structure test is unable to accurately capture the dynamic characteristics of the wind turbine under the combined action of multiple physical fields of wind, waves and currents due to equipment size limitations and difficulty in coordinating the scale ratio; the hybrid substructure test places too high requirements on the loading step.

[0005] In response to the deficiencies in the existing technology, the present application provides a full-process iterative hybrid test method for offshore floating wind turbines that can accurately simulate the dynamic response of wind turbines in complex marine environments while maintaining the controllability of test equipment and sites. Summary of the Invention

[0006] Therefore, in order to address the above-mentioned defects in the prior art, the present invention provides an offshore floating wind turbine full-process iterative hybrid test method that can accurately simulate the wind turbine dynamic response in a complex marine environment while maintaining the controllability of the test equipment and site.

[0007] The present invention discloses a full-process iterative hybrid test method for an offshore floating wind turbine. The offshore floating wind turbine is divided into two substructures: an upper wind turbine and a lower floating body. A full-time wind tunnel test is performed on the upper wind turbine substructure, and a full-time wave and current tank test is performed on the lower floating body substructure.

[0008] The specific steps include:

[0009] S1. Divide the offshore floating wind turbine into two substructures: the upper wind turbine and the lower floating body; place the upper wind turbine on the swing platform, input the initial state response time and the given wind field,

[0010] S2. Perform multiple iterations, input the current state time history and wind field, conduct a wind tunnel test, and obtain the tower base load response time history of the upper wind turbine under the current time history;

[0011] S3. Perform coordinate transformation on the tower base load response time history obtained in S2 to obtain the load time history acting on the lower floating body. Then, input a given wave and current load and simulate the output dynamic response time history of the floating body under wave and current loads and external loads through a wave and current tank test.

[0012] S4. Compare the dynamic response time history obtained in S3 with the input current state time history in S2. If the convergence judgment index constructed by the two meets the preset convergence tolerance, the experiment is considered complete and the process proceeds to S6. If the convergence judgment index constructed by the two does not meet the preset convergence tolerance, the update algorithm is used to calculate the input response time history for the next iteration and the process proceeds to S5.

[0013] S5. The new input response time obtained in S4 is input to the swing stage, and steps S2 to S4 are repeated;

[0014] S6. Record the last response time history of the tower base load of the upper wind turbine and the output power response time history of the lower floating body, which is the final response time history of the floating wind turbine.

[0015] Both wind tunnel tests and wave and current tank tests can be set up as physical tests, numerical tests, scaled tests or full-scale tests.

[0016] The update algorithm in S4 is set to the BFGS quasi-Newton algorithm or the Newton-Raphson iterative method.

[0017] The rocking platform has the ability to simulate six degrees of freedom of motion, namely, longitudinal swing, transverse swing, heave swing, pitching, rolling and bow swing.

[0018] The upper wind turbine substructure and the lower floating body substructure must satisfy the force boundary and motion state boundary coordination conditions.

[0019] The technical solution of the present invention has the following advantages:

[0020] The test method provided by the present invention divides the offshore floating wind turbine system into two substructures: the upper wind turbine and the lower floating body, and conducts full-time physical or numerical tests on each substructure. The full-time iteration method is used instead of a single iteration to avoid the time step competition problem. This method can accurately simulate the dynamic response of the wind turbine in a complex marine environment while maintaining the controllability of the test equipment and site.

[0021] That is, the full-process iterative hybrid test method of the present invention avoids the problem of competition between the simulation time step and the physical time step in traditional hybrid test methods, can greatly relax the test software and hardware requirements, and conduct larger and more complex hybrid tests, thereby more realistically simulating the dynamic performance of floating wind turbines under complex sea conditions; it overcomes many difficulties in traditional test methods for large offshore floating wind turbines, such as too small scale ratio, difficult to coordinate similarity relationships, and multi-field load distortion. This method has wide applicability and flexibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 This is a flow chart of the full-process iterative hybrid test method for an offshore floating wind turbine according to the present invention;

[0024] Figure 2 Schematic diagram of the physical wind tunnel test device of the present invention;

[0025] Figure 3 This is a schematic diagram of the wave flow pool test according to the present invention;

[0026] Figure 4 Schematic diagram of the iterative error convergence process of the BFGS algorithm of the present invention;

[0027] Figure 5 This is a schematic diagram of the time history of the dynamic response of the offshore floating wind turbine according to the present invention.

[0028] Reference numerals: 1- wind tunnel; 2- water pool; 101- swing platform; 102- fan; 103- flexible sealing connecting window; 201- floating body. DETAILED DESCRIPTION

[0029] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0030] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0031] Example 1: Figure 1 As shown, this embodiment provides a full-process iterative hybrid test method for an offshore floating wind turbine, which divides the offshore floating wind turbine into two substructures: an upper wind turbine and a lower floating body. A full-time wind tunnel test is performed on the upper wind turbine substructure, and a full-time wave and current tank test is performed on the lower floating body substructure. The wind tunnel test and the wave and current tank test can be set as any one of physical tests, numerical tests, scaled tests, or full-scale tests.

[0032] The specific steps include:

[0033] S1. Divide an offshore floating wind turbine into two substructures: an upper wind turbine and a lower buoy. Place the upper wind turbine on a swing platform, and input the initial state response time and a given wind field. The swing platform is capable of simulating six degrees of freedom (DOF) motion: surge, sway, heave, pitch, roll, and bow pitch.

[0034] S2. Perform multiple iterations, input the current state time history and wind field, conduct a wind tunnel test, and obtain the tower base load response time history of the upper wind turbine under the current time history;

[0035] The above two steps are for setting the initial response time. First, the control system sets an arbitrary initial input response time for the 6DOF swing platform 101 in the physical wind tunnel test. ( k =0 represents the initial moment), simulating the motion response of the fan 102 in the wind tunnel test. Figure 2 As shown, the wind turbine 102 is fixed on the 6DOF swing platform 101. The wind tunnel 1 simulates the actual marine environment wind load. The swing platform 101 applies motion boundary conditions to the bottom of the wind turbine 1 tower, and the tower base load time history is obtained through sensor measurement. Among them, 103 is a flexible sealing connecting window.

[0036] S3. Perform coordinate transformation on the tower base load response time history obtained in S2 to obtain the load time history acting on the lower floating body. Then, input a given wave and current load and simulate the output dynamic response time history of the floating body under wave and current loads and external loads through a wave and current tank test.

[0037] Step S3 is the wave and current pool test to simulate the movement of the floating body, that is, the tower base load time history obtained in the physical wind tunnel 1 test Perform coordinate transformation to obtain the load time history acting on the lower floating body 201 , input into the floating body 201 model of the wave and current tank test, such as Figure 3 As shown, reference numeral 2 is a pool 2; the wave and current pool test is simulated using a floating body hydrodynamic analysis software (such as ANSYS AQWA, SESAM, etc.), and the software is used to perform a dynamic analysis of the floating body 201 under the combined action of external loads and ocean wave loads, and the dynamic response time history of the floating body 201 is obtained. .

[0038] S4. Compare the dynamic response time history obtained in S3 with the input current state time history in S2. If the convergence judgment index constructed by the two meets the preset convergence tolerance, the experiment is considered to be completed and enter S6. If the convergence judgment index constructed by the two does not meet the preset convergence tolerance, the update algorithm is used to calculate the input response time history of the next iteration and enter S5. Among them, the update algorithm is set to the BFGS quasi-Newton algorithm or the Newton-Raphson iterative method.

[0039] S5. The new input response time obtained in S4 is input to the swing stage, and steps S2 to S4 are repeated;

[0040] That is, the dynamic response time history of the floating body 201 in the wave and current pool test is obtained. Then, the BFGS quasi-Newton algorithm is used to optimize the calculation, as shown in Figure 4 As shown; the dynamic response time history of the floating body 201 obtained from the wave flow pool test Input response time For comparison, the input response time history of the next iteration step is obtained by updating the BFGS algorithm ,Right now .in, is the update operator obtained by BFGS, and The above algorithm can gradually approach the actual response.

[0041] This process is iterated continuously until the convergence tolerance is met. and output response time The second norm of is the convergence index, ; Take the convergence tolerance ;when When it converges, the iteration ends.

[0042] S6. Record the last response time history of the upper wind turbine's tower base load and the output dynamic response time history of the lower floating structure. This is the final response time history of the floating wind turbine. That is, when the iteration results meet the convergence conditions, the test ends. The response time history calculated in the last wave-flow tank test will be used as the final dynamic response time history of the floating wind turbine. Figure 5 The time history diagrams of the dynamic response of offshore floating wind turbines under six conditions: longitudinal surge, transverse surge, heave, pitch, roll and bow pitch are displayed.

[0043] The response time history finally determined by the method of this embodiment reflects the actual dynamic response of the floating wind turbine in a complex marine environment, and can provide a basis for the design, analysis and optimization of the floating wind turbine.

[0044] In this embodiment, the upper wind turbine substructure and the lower floating body substructure need to satisfy the force boundary and motion state boundary coordination conditions, that is, they must be less than a specified convergence tolerance limit.

[0045] In summary, compared to existing technologies, the full-process iterative hybrid test method proposed in this application avoids the competition between simulation time steps and physical time steps in traditional hybrid test methods. This significantly relaxes the test hardware and software requirements, allowing for larger and more complex hybrid tests, thereby more realistically simulating the dynamic performance of floating wind turbines under complex sea conditions. This method overcomes many challenges inherent in traditional testing methods for large offshore floating wind turbines, such as insufficient scale ratios, difficulty coordinating similarity relationships, and multi-field load distortion. This method offers broad applicability and flexibility.

[0046] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. The full-process iterative hybrid test method for offshore floating wind turbines is characterized by: The offshore floating wind turbine is divided into two substructures: the upper wind turbine and the lower floating body. The upper wind turbine substructure is subjected to a full-time wind tunnel test, while the lower floating body substructure is subjected to a full-time wave and current tank test. The specific steps include: S1. Divide the offshore floating wind turbine into two substructures: the upper wind turbine and the lower floating body; place the upper wind turbine on the swing platform, input the initial state response time and the given wind field, S2. Perform multiple iterations, input the current state time history and wind field, conduct a wind tunnel test, and obtain the tower base load response time history of the upper wind turbine under the current time history; S3. Perform coordinate transformation on the tower base load response time history obtained in S2 to obtain the load time history acting on the lower floating body. Then, input a given wave and current load and simulate the output dynamic response time history of the floating body under wave and current loads and external loads through a wave and current tank test. S4. Compare the dynamic response time history obtained in S3 with the input current state time history in S2. If the convergence judgment index constructed by the two meets the preset convergence tolerance, the experiment is considered complete and the process proceeds to S6. If the convergence judgment index constructed by the two does not meet the preset convergence tolerance, the update algorithm is used to calculate the input response time history for the next iteration and the process proceeds to S5. S5. The new input response time obtained in S4 is input to the swing stage, and steps S2 to S4 are repeated; S6. Record the final response time history of the upper wind turbine tower base load and the output power response time history of the lower floating structure, which is the final response time history of the floating wind turbine. Among them, the update algorithm in S4 is set to the BFGS quasi-Newton algorithm or the Newton-Raphson iterative method; the wind tunnel test is a physical test, and the wave and current tank test is simulated using the floating body hydrodynamic analysis software.

2. The full-process iterative hybrid test method for offshore floating wind turbines according to claim 1 is characterized in that: The rocking platform has the ability to simulate six degrees of freedom of motion, namely, longitudinal swing, transverse swing, heave swing, pitching, rolling and bow swing.

3. The full-process iterative hybrid test method for offshore floating wind turbines according to claim 1 is characterized in that: The upper wind turbine substructure and the lower floating body substructure must satisfy the force boundary and motion state boundary coordination conditions.

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