Multi-point and multi-direction complex load simulation system and method for wind turbine under marine scouring environment

Abstract

The application discloses a wind turbine multi-point and multi-direction complex load simulation system and method under a marine scour environment, and belongs to the technical field of offshore wind power. Three sets of load simulation devices are installed on the wind turbine tower model of the scour environment simulation device, which are respectively: the load simulation device for simulating the wind load acting on the wind turbine is located below the top mass block of the wind turbine tower model, the load simulation device for simulating the wave load acting on the wind turbine is located above the water surface of the sand pool, and the load simulation device for simulating the extreme condition wave load acting on the wind turbine is located at the equivalent position of the average wave height under the extreme condition above the water surface of the sand pool. The application realizes the accurate simulation of the complex offshore wind turbine environmental load by arranging the combined cyclic load simulation devices at three positions on the model with different heights and different angles, lays a foundation for exploring the full life service performance evolution law of the offshore wind turbine and other high-rise marine structures, and perfecting the design of the marine deep water foundation.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of offshore wind power, and particularly relates to a wind turbine multi-point and multi-direction complex load simulation system and method under marine scouring environment. BACKGROUND

[0002] In recent years, with the growth of demand for clean energy in countries around the world, the offshore wind power industry has developed rapidly due to its clean and efficient, low-scale development difficulty compared with traditional energy. However, the environment during the operation of offshore wind turbines is complex, and the cyclic load generated by wind and wave flow and the long-term scouring effect of sea waves will change the stiffness of the overall system of the wind turbine and its natural frequency, thus causing safety hazards. Therefore, it is necessary to conduct in-depth research on the performance evolution law of high-rise marine structures such as offshore wind turbines.

[0003] However, most of the current related test platforms are difficult to accurately apply wind and wave loads and marine environment scouring conditions to the wind turbine during design, and cannot accurately simulate the long-term load of the wind turbine in the scouring environment: the existing test platform mostly uses a point equivalent load loading method to simulate the wind and wave loads of the wind turbine, which leads to the coincidence of the frequency and size of the two loads and the application point, obviously deviating from the actual situation, and causing a large error; at the same time, the existing test loading device mostly uses servo loading, loading rod and other means, which are often high in cost, complicated to install or unable to accurately apply loads; for scouring, the existing test platform mostly adopts the method of excavating a scour pit to simulate the scour pit by estimating the scouring depth, which cannot realize long-term scouring physical means simulation and does not conform to the real engineering environment; at the same time, the cyclic loading device in some test platforms that use physical means to simulate wave flow scouring is generally relatively bulky and difficult to accurately control the application of loads; in summary, in order to break through the technical bottleneck of the existing test platform that is difficult to accurately apply wind and wave loads, make up for the defects of the existing wave flow tank test that is difficult to accurately realize multi-point, multi-direction and long-term irregular cyclic combination loading, establish an accurate, portable and easy-to-realize multi-point and multi-direction long-term irregular cyclic combination loading device under the action of wave flow scouring, lay a test method for improving the design of marine deepwater foundation and has outstanding significance for exploring the full-life service performance evolution law of offshore wind turbines and other high-rise marine structures. SUMMARY

[0004] The application aims to provide a wind turbine multi-point and multi-direction complex load simulation system and method under marine scour environment, which can equivalently convert the wind load on the wind turbine into irregular long-term cyclic loads in different directions and at different heights, and can realize accurate simulation of the marine environment load by arranging and combining the cyclic loading devices at multiple points and multiple angles on the model, collecting the force conditions of the wind turbine model transmitted by the sensors in real time through the computer, breaking through the technical bottleneck that the existing test platform is difficult to accurately control the marine environment load, and making up the defects that the multi-point, multi-direction and long-term irregular cyclic combined loading cannot be accurately realized in the existing wave-current flume test, thereby laying a foundation for the test method for exploring the full-life service performance evolution law of offshore wind turbines and other high-rise marine structures and improving the design of marine deepwater foundation.

[0005] The above-mentioned purpose is achieved by the following technical solutions:

[0006] The application first provides a wind turbine multi-point and multi-direction complex load simulation system under marine scour environment, which comprises a scour environment simulation device, the scour environment simulation device has a sand sink therein, a wave generator and a water pump are installed in the scour environment simulation device, a wind turbine scale model is installed in the sand sink, the wind turbine scale model comprises a single pile foundation model, the single pile foundation model is connected to a wind turbine tower model through a flange, a counterweight block for equivalent wind turbine mass is arranged at the top end of the wind turbine tower model, three sets of load simulation devices are installed on the wind turbine tower model, the three sets of load simulation devices are respectively: a load simulation device for simulating the wind load on the wind turbine is located below the mass block at the top end of the wind turbine tower model, a load simulation device for simulating the wave load on the wind turbine is located at the water surface above the mud surface of the sand sink, and a load simulation device for simulating the extreme condition wave load on the wind turbine is located at the equivalent position of the average wave height under the extreme condition above the water surface of the sand sink.

[0007] Further, the load simulation device is based on the centrifugal principle, and the specific structure comprises a fixer, a fixing steel pipe and a transmission box, the fixer is connected to the transmission box through the fixing steel pipe, and the loading direction of the load simulation device can be adjusted by rotating the load simulation device around the central axis of the wind turbine tower model in the horizontal direction; the transmission box is internally provided with a motor, two meshed and chained large gears and a small gear connected to the motor are arranged on the transmission box, one same mass block is eccentrically arranged on each of the two meshed and chained large gears, the small gear is meshed with one of the large gears, and the motor in the transmission box drives the small gear to rotate, thereby driving the chained large gears to rotate; when rotating, the large gears generate cyclic loads due to the unbalanced rotation of the eccentric mass attached thereto, and the generated loads are transmitted to the transmission box and then to the wind turbine tower model, thereby realizing the load simulation on the wind turbine model.

[0008] Further, the load simulation device for simulating the extreme condition wave load of the wind turbine is located at the equivalent position of the average wave height under the extreme condition above the horizontal plane, specifically, the average wave height value in the 100-year or 50-year wind wave of the wind turbine The equivalent height distance h of the installation position of the load simulation device from the water surface of the sand trap a That is Wherein a is the scale ratio of the wind turbine scale model.

[0009] Further, each set of the load simulation device is installed with an accelerometer, and the accelerometer is connected with the laser vibration meter to realize the detection and data collection of the load size and direction of the three sets of load simulation devices on the wind turbine tower model in the wind turbine scale model, and the load bearing condition of the wind turbine under the scour environment is monitored in real time.

[0010] The application also provides a method for simulating the multi-point and multi-direction complex load bearing of the wind turbine under the marine scour environment by using the wind turbine multi-point and multi-direction complex load bearing simulation system under the marine scour environment.

[0011] S1. Firstly, the size of the scour environment simulation device is determined, the size and mass of the wind turbine scale model are determined according to the scale ratio a of the wind turbine scale model, the soil parameters in the sand trap, and the physical indexes related to the water power conditions, then the scour environment simulation device is installed, the sand is laid in the sand trap to form a sand bed, and the wind turbine model is placed in the sand trap and the soil surface is flattened;

[0012] S2. The sizes of the wind load Th, the wave load F wave and the extreme condition wave load F wave max are determined: at the wind turbine site selected for the test research, the environmental data under the actual operation condition of the wind turbine are collected, including the wind speed, the wind direction, the effective wave height, the wind and wave period; the environmental data are grouped for calculation to obtain the wind load Th, the wave load F wave and the extreme condition wave load F wave max , the load frequency ratio of each group, and the load application frequency of each group; the output power of the three sets of load simulation devices is realized by adjusting the angular velocity ω of the transmission motor of the three sets of load simulation devices;

[0013] S3. The azimuth of the installation of the three sets of load simulation devices is determined according to the collected environmental data;

[0014] S4. The wind load Th, the wave load F wave and the extreme condition wave load F wave maxThe size of the wind load Th and step S3 determines the orientation of the three sets of load simulation devices installed, the application time of each group of loads is determined according to the frequency ratio of each group, the loading program of the wind turbine is set, the mass of the mass block in the load simulation device, the diameter of the gear and the gear speed are determined, the force sensor is connected with the load simulation device, the cycle load is tested in advance to meet the requirements, after the test is completed, the load simulation device and the force sensor are disconnected, the load simulation device is fixed at the specified loading point position of the wind turbine model, and the installation angle of the load simulation device and the initial position of the gear in the device are adjusted, and the fastening degree of the transmission and the wind turbine tower body is checked to ensure that the force can be directly transmitted to the structure at the beginning of the test;

[0015] S5. Laser vibration meters are configured outside the wind turbine model, and MEMS accelerometers are installed on each cycle load simulation device for monitoring the structural acceleration of each part of the single-pile model tower to calculate the load received;

[0016] S6. After all the equipment is connected, test whether the laser vibration meter and the acceleration sensor are working normally, start the wave-making flow function of the scour environment simulation device to simulate the scour condition, start the power of the loading transmission machine, and apply the cycle load to the single-pile model at different angles by the load simulation device, which is used to accurately simulate the multi-directional environmental load of the wind turbine under the marine scour environment.

[0017] Further, the specific method of step S2 is:

[0018] S2-1. Determine the size of the wind load Th: divide the environmental data of the site of the wind turbine to be tested into four groups according to the wind speed, which are n1 data before the wind speed is lower than the wind speed of the wind turbine, n2 data between the wind speed of the wind turbine and the rated wind speed, n3 data between the rated wind speed of the wind turbine and the cut-out wind speed, and n4 data beyond the cut-out wind speed;

[0019] The weighted average value of each group of wind speeds is calculated according to the frequency ratio of each wind speed Wherein, a i represents the number of times each wind speed appears, U i represents each wind speed value, which is then converted into wind load data by the following formula:

[0020]

[0021] Wherein ρ a is the air density, A R is the swept area of the wind turbine rotor, C T is the thrust coefficient, which is calculated according to when the wind turbine operates at constant power, wherein U R is the rated wind speed of the wind turbine;

[0022] S2-2. Determine wave load F wave , using Morison wave equation, whose maximum value is calculated as follows:

[0023]

[0024] where S is the average sea depth at the site of the wind turbine under test; D P is the diameter of the wind turbine pile under test; p w is the density of water; C D and C M are the drag and inertia coefficients, respectively, which are conservatively taken as 1.0 and 2.0, respectively; and η is the sea surface elevation at the site of the wind turbine under test, expressed as η = H , where H is the average wave height, T is the wind wave period, and k is the wave number, which is calculated according to the wave angular frequency ω k , ω k 2 = gk tanh(kS), , t is time, and x is the horizontal distance between the wave and the pile;

[0025] S2-3. Determine the extreme condition wave load F wave max : take the average wave height data H max collected from the environmental data of the site where the wind turbine is actually operated for 100 years or 50 years, i.e., the fifth group of load data, to obtain F wave max according to the following formula:

[0026]

[0027] S2-4. Calculate the frequency ratio of the five groups of loads: the five groups of loads include n1 data before the wind speed is lower than the cut-in wind speed of the wind turbine, n2 data between the cut-in wind speed and the rated wind speed of the wind turbine, n3 data between the rated wind speed and the cut-out wind speed of the wind turbine, n4 data beyond the cut-out wind speed, and the average wave height data H max collected from the environmental data of the site where the wind turbine is actually operated for 100 years or 50 years.

[0028] The frequency ratio of each group of loads where q is taken as 1, 2, 3, 4, and 5; since the fifth group of loads is the load under extreme conditions, which appears less in actual situations, n5 can be taken as 5%∑n q , where q is taken as 1, 2, 3, and 4.

[0029] S2-5. Let the mass of the mass block in the load simulation device be m; the radius of the gear be r; and the angular velocity of the gear be ω; then the cyclic load output by the load simulation device to the wind turbine model is F = F 1y +F 2y= 2mr omega 2 sin theta, wherein F ay , F 2y respectively represent the y-axis component of the force of the two gear pairs on the fan model, the x-axis component of the force of the two gear pairs on the fan model is equal in magnitude and opposite in direction, and cancels out to zero, theta represents the included angle between the line connecting the mass block and the center of the gear and the x-axis, and the extreme value of the cyclic load is F max = F 1y max + F 2y max = 2mr omega 2 The cyclic load size can be achieved by adjusting the transmission box and thus adjusting the angular velocity omega of the gear, and omega is the load application frequency; F max are respectively equal to Th, f wave , F wave max and the product of the fan model scale ratio a is used for the equivalent of the wind load Th, the wave load F wave and the extreme condition wave load F wave max The application frequency omega q of the five groups of loads (q takes 1, 2, 3, 4, and 5) is calculated by the formula .

[0030] Further, the specific method of step S3 is: five groups of loads are respectively generated into wind and wave rose diagrams according to the frequency of the occurrence of the load direction data of each group in the group, the center of the diagram represents the fan tower body, different lines represent the mean load of different groups, the direction pointed by the line point to the center of the circle is the action direction of the load, and the distance between the line point and the center of the circle represents the frequency of the occurrence of the load; the direction of the point farthest from the center of the line is taken as the load action direction, and the main action direction of the load obtained from the rose diagram is the installation direction of the load simulation device.

[0031] The beneficial effects of the present application are:

[0032] 1. The sea wave flow scouring environment is a basic environmental condition for the service of the fan and is also a load condition that accompanies the fan for a long time. The present application simulates the scouring effect of the sea wave on the fan by using the real hydraulic conditions of the wave-current flume and the sedimentation tank, uses physical means in the wave-current flume to truly create the scouring environment of the offshore fan model, and can simultaneously carry out tests under the combined action of the long-term cyclic load of the offshore fan and the scouring evolution process of the wave flow.

[0033] 2. The cyclic loading device of the present application is designed to solve the problem that the load loading device is heavy and difficult to accurately control the load. The loading device is light in structure, clear in force transmission, and can be easily installed on the fan scale model. The size and frequency of the load applied by the loading device are adjusted in real time through the sensor connected to the computer, accurately controlling the application of multi-point horizontal cyclic load in different directions to the fan tower model. Compared with other cyclic loading devices, the stress conditions during actual operation of the fan can be more accurately simulated; the device principle is simple, durable, easy to maintain, and stable.

[0034] 3. The present application is aimed at the working condition of the fan daily subjected to environmental loads such as wind and wave flow. The wind load and wave load are respectively equivalent to long-term cyclic loads applied in different directions and at different heights. The cyclic loading device is combined and arranged in multiple points and multiple angles, and together with the wave-current tank, the simulation of the above-mentioned marine environmental loads is realized, breaking through the technical bottleneck of accurately controlling marine environmental loads in the existing test platform, making up for the defects of accurately realizing multi-point, multi-direction, and long-term irregular cyclic combination loading in the existing wave-current tank test, and establishing a device for accurately, easily and realizing multi-point and multi-direction long-term irregular cyclic combination loading under the action of wave flow scour, which lays the test method for perfecting the design of marine deepwater foundation and has outstanding significance for exploring the full-life service performance evolution law of offshore wind turbines and other high-rise marine structures. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 is the overall structure schematic diagram of the present application (the installation height and direction of the load simulation device in the figure are only examples);

[0036] Figure 2 is the structure schematic diagram of the load simulation device of the present application;

[0037] Figure 3 is the equivalent principle diagram of the load simulation device of the present application;

[0038] Figure 4 is the load rose diagram generated in the load calculation of the present application, Figure 4 (a) is a wind rose diagram, and (b) is a wave rose diagram;

[0039] Figure 5 is is the horizontal load waveform diagram generated by the load simulation device of the present application;

[0040] LIST OF FIGURES:

[0041] Mass block 1, load simulation device 2, fan model tower 3, flange 4, single pile foundation model 5, sand trap 6, scouring environment simulation device 7, wave generator and water pump 8, laser vibration meter 9, attached gear mass 10, interlocking gear wheel 11, transmission pinion 12, transmission box 13, square fixer 14, fixed steel pipe 15. Detailed Implementation

[0042] The principles and specific embodiments of the present invention will be further explained below with reference to the accompanying drawings. It should be understood that the following principles and specific embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0043] like Figure 1 As shown, this invention first provides a multi-point, multi-directional complex load simulation system for wind turbines under marine scouring environments. The system aims to simulate the complex loads experienced by wind turbines under marine scouring conditions, particularly for accurate simulation and analysis of the stress conditions of wind turbines under extreme sea conditions. The system includes a scouring environment simulation device 7, which contains a sedimentation tank 6 to simulate the scouring effects of water flow and sediment in the marine environment. The device 7 is equipped with a wave generator and a water pump 8, capable of generating periodic waves and water flow to simulate the complex flow conditions of the marine environment. A scaled-down model of the wind turbine is installed in the sedimentation tank. This scaled-down model includes a monopile foundation model 5, which is connected to a wind turbine tower model 3 via a flange 4. The top of the wind turbine tower model 3 is equipped with... A counterweight block 1 for simulating the mass of an equivalent wind turbine is placed on the wind turbine tower model 3. Three load simulation devices 2 are installed on the wind turbine tower model 3. The three load simulation devices 2 are as follows: the load simulation device 2 for simulating the wind load on the wind turbine is located below the top mass block 1 of the wind turbine tower model 3; the load simulation device 2 for simulating the wave load on the wind turbine is located above the mud surface of the sedimentation tank at the water surface; and the load simulation device 2 for simulating the wave load under extreme conditions on the wind turbine is located above the water surface of the sedimentation tank 6 at the equivalent position of the average wave height under extreme conditions.

[0044] like Figure 2 As shown, the load simulation device 2 in this embodiment is based on the centrifugal principle. Its specific structure includes a fixture 14, a fixing steel pipe 15, and a transmission box 13. The fixture 14 is connected to the transmission box 13 through the fixing steel pipe 15. The loading direction of the load simulation device 2 can be adjusted by rotating the load simulation device 2 around the central axis of the wind turbine tower model 3 in the horizontal plane. The transmission box 13 contains a motor. Two meshing interlocking large gears 11 and a small gear 12 connected to the motor are installed on the transmission box 13. The two meshing interlocking large gears 11 are respectively eccentrically provided with an identical mass block 10. The small gear 12 meshes with one of the large gears 11. The motor in the transmission box 13 drives the small gear 12 to rotate, thereby driving the interlocking large gears 11 to rotate. When rotating, the large gear 11, due to the attached mass block 10, generates a cyclic load due to its own eccentric unbalanced rotation. The generated load is transferred to the transmission box and then to the wind turbine tower model 3, realizing the load simulation of the wind turbine model 3.

[0045] The load simulation device 2 for simulating the extreme condition wave load of the wind turbine in the embodiment is located at the equivalent position of the average wave height under the extreme condition above the horizontal plane, specifically, the average wave height value in the 100-year or 50-year wind wave of the wind turbine The equivalent height distance h of the installation position of the load simulation device from the water surface of the sand trap 6 a That is Wherein a is the scale ratio of the wind turbine scale model.

[0046] In the embodiment, the accelerometer is installed on each set of load simulation devices 2, and the accelerometer is connected with the laser vibration meter 9 to realize the detection and data collection of the load size and direction applied by the three sets of load simulation devices 2 on the wind turbine tower model 3 in the wind turbine scale model, and the load bearing condition of the wind turbine under the scour environment is monitored in real time.

[0047] The application also provides a method for simulating the multi-point and multi-direction complex load bearing of the wind turbine under the ocean scour environment by using the wind turbine multi-point and multi-direction complex load simulation system under the ocean scour environment, and the method comprises the following steps:

[0048] S1. Firstly, the size of the scour environment simulation device 7 is determined, the size and mass of the wind turbine scale model are determined according to the scale ratio a of the wind turbine scale model, the soil parameters in the sand trap 6, and the physical indexes related to the hydraulic conditions, then the scour environment simulation device 7 is installed, the sand in the sand trap 6 is laid to form, and the wind turbine model is placed in the sand trap 6, and the soil surface is flattened;

[0049] S2. The sizes of the wind load Th, the wave load F wave and the extreme condition wave load F wave max are determined: the environmental data under the actual operation condition of the wind turbine are collected at the wind turbine site selected for the test research, including the wind speed, the wind direction, the effective wave height, the wind and wave period, the environmental data are grouped for calculation, the wind load Th, the wave load F wave and the extreme condition wave load F wave max under the actual operation condition of the wind turbine, the load frequency ratio of each group, and the load application frequency of each group are obtained, and the output power of the three sets of load simulation devices 2 is realized by adjusting the angular velocity ω of the transmission motor of the three sets of load simulation devices 2;

[0050] S3. The azimuth of the installation of the three sets of load simulation devices 2 is determined according to the collected environmental data;

[0051] S4. The wind load Th, the wave load F wave and the extreme condition wave load F wave maxThe size of the wind load Th and step S3 determines the orientation of the three sets of load simulation devices 2 installed, the application time of each group of loads is determined according to the frequency ratio of each group, and the loading program of the wind turbine loading is set; the mass of the mass block 10 in the load simulation device, the diameter of the gear 11 and the gear rotation speed are determined, the force sensor is connected with the load simulation device 2, the cycle load is tested in advance to see whether it meets the requirements, after the test is completed, the load simulation device 2 is disconnected with the force sensor, the load simulation device 2 is fixed at the specified loading point position of the wind turbine model, and the installation angle of the load simulation device 2 and the initial position of the gear in the device are adjusted, and the fastening degree of the transmission and the wind turbine tower body is checked to ensure that the force can be directly transmitted to the structure at the beginning of the test;

[0052] S5. The laser vibration meter 9 is arranged outside the wind turbine model, and the MEMS accelerometer is installed on each cycle load simulation device for monitoring the structural acceleration of each part of the single-pile model tower body to calculate the load condition;

[0053] S6. After all the equipment is connected, it is tested whether the laser vibration meter and the acceleration sensor work normally, the wave flow function of the scour environment simulation device is started to simulate the scour condition, the power of the loading transmission machine is turned on, and the load simulation device applies the cycle load to the single-pile model at different angles, which is used to accurately simulate the multi-directional environmental load of the wind turbine under the marine scour environment.

[0054] Further, the specific method of step S2 is:

[0055] S2-1. Determine the size of the wind load Th: divide the environmental data of the site of the wind turbine to be tested into four groups according to the wind speed, which are n1 data before the wind speed is lower than the cut-in wind speed of the wind turbine, n2 data between the cut-in wind speed and the rated wind speed of the wind turbine, n3 data between the rated wind speed and the cut-out wind speed of the wind turbine, and n4 data beyond the cut-out wind speed;

[0056] The weighted average value of each group of wind speeds is calculated according to the frequency ratio of each wind speed Wherein, a i represents the number of times each wind speed appears, U i represents each wind speed value, which is then converted into wind load data by the following formula:

[0057]

[0058] Wherein p a is the air density, A R is the swept area of the wind turbine rotor, C T is the thrust coefficient, which is calculated according to when the wind turbine operates at constant power, wherein U R is the rated wind speed of the wind turbine;

[0059] S2-2. Determine the wave load F wave The maximum value is calculated using the Morison wave equation, and the formula is as follows:

[0060]

[0061] Where S is the average sea depth at the wind turbine site selected in the experimental study; D P The diameter of the wind turbine pile used in the experimental study; ρ w C is the density of water. D and C M Here, η represents the drag and inertia coefficients, which can be conservatively taken as 1.0 and 2.0 respectively; η is the sea surface elevation at the wind turbine site selected in the experimental study, expressed as η = 1.0. The expression is given, where H is the average wave height, T is the wave period, and k is the wave number, based on the wave angular frequency ω. k ω is calculated. k 2 =gk tanh(kS), Calculation, where t is time and x is the horizontal distance between the wave and the pile;

[0062] S2-3. Determine the wave load F under extreme conditions. wave max Size: The average wave height H value collected from environmental data of a 100-year or 50-year return period at the actual operating location of the wind turbine. max This is the fifth set of load data, and F is obtained using the following formula. wave max :

[0063]

[0064] S2-4. Calculate the frequency ratio of the five load groups: The five load groups include: n1 data points with wind speeds below the wind turbine cut-in speed; n2 data points with wind speeds between the wind turbine cut-in speed and the rated wind speed; n3 data points with wind speeds between the wind turbine's rated wind speed and the cut-out wind speed; n4 data points with wind speeds exceeding the cut-out wind speed; and the average wave height data H collected from environmental data of a 100-year or 50-year return period at the actual operating location of the wind turbine. max ;

[0065] Frequency ratio of each load group Where q takes values ​​of 1, 2, 3, 4, and 5; since the fifth group of loads represents extreme cases and occurs less frequently in practice, n5 can be taken as 5%∑n. q Here, q can be 1, 2, 3, or 4.

[0066] S2-5. Let the mass of the mass block 10 in the load simulation device 2 be m; the radius of the large gear 11 be r; and the angular velocity of the large gear 11 be ω; as follows: Figure 3 As shown, Figure 3 In the equation, centrifugal force: F1=mrω2 , F2=mrω 2 ; centrifugal force x direction component: F 1x =F1cosθ, F 2x =F2cosθ; centrifugal force y direction component: F 1y =F1sinθ, F 2y =F2sinθ; therefore x direction resultant force: F x =F 1x +F 2x ; y direction resultant force: F y =F 1y +F 2y ; then the cyclic load outputted by the load simulation device 2 to the wind turbine model is F=F 1y +F 2y =2mrω 2 sinθ, wherein F 1y , F 2y respectively represent the y axis component of the force exerted by the two bull gears 11 on the wind turbine model, the x axis component of the force exerted by the two bull gears 11 on the wind turbine model is equal in size and opposite in direction, and cancels out to zero, θ represents the included angle between the line connecting the mass block and the center of the bull gear 11 and the x axis, then the extreme value of the cyclic load is F max =F 1y max +F 2y max =2mrω 2 , the size of the cyclic load can be achieved by adjusting the transmission box 13 and thus adjusting the angular velocity ω of the bull gear, ω being the load application frequency; let F max respectively equal to the product of Th, F wave , F wave max and the scale ratio a of the wind turbine model for the equivalent of the wind load Th, the wave load F wave and the extreme condition wave load F wave max ; five groups of load application frequencies ω q (q takes 1, 2, 3, 4, 5) are calculated respectively by the formula .

[0067] Further, the specific method of step S3 is to generate wind and wave rose diagrams for the five groups of loads according to the frequency of the occurrence of the load direction data of each group. For example, as shown in the accompanying drawings, the center of the circle represents the wind turbine tower, different lines represent the mean loads of different groups, the direction pointed to by the line connecting the point on the line and the center of the circle is the direction of the load, and the distance between the point on the line and the center of the circle represents the frequency of the occurrence of the load; the direction of the point farthest from the center of the circle is taken as the direction of the load, for example Figure 4 (a), point A represents the direction of the wind load of 8-12 m / s, and point D represents the direction of the wind load exceeding 12 m / s; Figure 4 Figure 4 ​(b) In the middle, E point represents the direction of 4-8m wave height wave load. The main load direction obtained from the rose diagram is the installation direction of the load simulation device.

[0068] As Figure 5 When m=1, ω=1, and r=1, the horizontal load waveform generated by the load simulation device of the present application can equivalent the wind load on the fan to irregular long-term cyclic loads in different directions and heights. Through the multi-point and multi-angle layout of the cyclic loading device on the model, and the real-time collection of the force condition of the fan model by the computer through the sensors, the accurate simulation of the marine environmental load is realized.

Claims

1. A multi-point and multi-direction complex load simulation system for a wind turbine in an ocean scouring environment, the system comprising a scouring environment simulation device (7) having a sand sink (6) therein, a wave generator and a water pump (8) being installed in the scouring environment simulation device (7), a wind turbine scale model being installed in the sand sink, the wind turbine scale model comprising a single-pile foundation model (5), the single-pile foundation model (5) being connected to a wind turbine tower model (3) through a flange (4), a top mass (1) for equivalent wind turbine mass being arranged at a top end of the wind turbine tower model (3), characterized in that, Three sets of load simulation devices (2) are installed on the fan tower model (3), and the three sets of load simulation devices (2) are respectively: a load simulation device (2) for simulating the wind load acting on the fan is located below the top mass block (1) of the fan tower model (3), a load simulation device (2) for simulating the wave load acting on the fan is located above the water surface of the sand pool, and a load simulation device (2) for simulating the extreme condition wave load acting on the fan is located at the equivalent position of the average wave height under the extreme condition above the water surface of the sand pool (6), specifically the average wave height value in the wind wave of the fan 100-year or 50-year The installation position of the load simulation device is equivalent to the height distance h of the water surface of the sand pool (6) from the water surface a That is Wherein a is the scale ratio of the fan scale model Determination of wind load Th, wave load F wave and extreme condition wave load F wave max : the output power of the three sets of load simulation devices (2) is realized by adjusting the angular velocity ω of the transmission motor of the three sets of load simulation devices (2); the azimuth of the installation of the three sets of load simulation devices (2) is determined according to the collected environmental data, and specifically, the frequency ratios of five groups of loads are calculated: the five groups of loads include n1 data before the wind speed is lower than the cut-in wind speed of the wind turbine, n2 data between the cut-in wind speed and the rated wind speed of the wind turbine, n3 data between the rated wind speed and the cut-out wind speed of the wind turbine, n4 data beyond the cut-out wind speed, and average wave height data value H max collected from the environmental data of 100-year or 50-year occurrence of the actual operation of the wind turbine ; the frequency ratio of each group of loads q where q takes 1, 2, 3, 4, 5; since the fifth group of loads is the load in the extreme condition, which appears less in the actual situation, n5=5%∑n q may be taken, where q takes 1, 2, 3, 4; the wind and wave rose diagrams of the five groups of loads are generated according to the frequency of the respective load direction data of each group of loads in the group, the center of the rose diagram represents the wind turbine tower, different lines represent the mean load of different groups, the direction pointed by the connecting line between the point on the line and the center represents the action direction of the load, and the distance between the point on the line and the center represents the frequency of the occurrence of the load; the direction of the farthest point of each line from the center is taken as the action direction of the load, and the main action direction of the load obtained from the rose diagram is the installation azimuth of the load simulation device.

2. The system for simulating complex loadings of a wind turbine in a marine scour environment according to claim 1, wherein, The load simulation device (2) is based on the centrifugal principle, and the specific structure comprises a fixer (14), a fixing steel pipe (15) and a transmission box (13). The fixer (14) is connected with the transmission box (13) through the fixing steel pipe (15), and the loading direction of the load simulation device (2) can be adjusted by rotating the load simulation device (2) around the central axis of the fan tower body model (3) in the horizontal direction. The transmission box (13) is internally provided with a motor, and two meshed and chained large gears (11) and a small gear (12) connected with the motor are mounted on the transmission box (13). The two meshed and chained large gears (11) are respectively provided with one same attached gear mass block (10) eccentrically arranged thereon. The small gear (12) is meshed with one of the large gears (11), and the motor in the transmission box (13) drives the small gear (12) to rotate, thereby driving the chained large gears (11) to rotate. When rotating, the large gears (11) generate cyclic loads due to the eccentric imbalance of their own mass because of the attached gear mass blocks (10), and the generated loads are transmitted to the transmission box and then to the fan tower body model (3), so that the load simulation of the fan tower body model (3) is realized.

3. The system of claim 1, wherein, The load simulation device (2) for simulating the extreme condition wave load of the fan is located at the equivalent position of the average wave height under the extreme condition above the horizontal plane.

4. The system for multi-point and multi-direction complex load simulation of a wind turbine in an ocean scour environment according to claim 1, wherein, Each set of the load simulation device (2) is provided with an accelerometer, and the accelerometer is connected with a laser vibration meter (9) to realize the detection and data collection of the load size and direction of three sets of load simulation devices (2) on the fan tower body model (3) in the fan scale model, so that the loading condition of the fan under the scouring environment is monitored in real time.

5. A method for simulating the complex multi-point and multi-directional load of a wind turbine in a marine scouring environment by using the system for simulating the complex multi-point and multi-directional load of a wind turbine in a marine scouring environment according to any one of claims 1-4, characterized in that, The implementation of the method comprises the following steps: S1. Firstly, the size of the scouring environment simulation device (7) is determined, the size and mass of the fan scale model are determined according to the scale ratio a of the fan scale model, the soil parameters and the physical indexes related to the hydraulic conditions in the sand trap (6) are determined, then the scouring environment simulation device (7) is installed, the sand in the sand trap (6) is laid to form and the fan model is placed in the sand trap (6), and the soil surface is leveled; S2. Determine the size of wind load Th, wave load F wave and extreme condition wave load F wave max : At the site of the wind turbine selected for testing, environmental data under actual operating conditions of the wind turbine are collected, including wind speed, wind direction, significant wave height, wind and wave period; the environmental data are grouped for calculation to obtain wind load Th, wave load F wave and extreme condition wave load F wave max under actual operating conditions of the wind turbine, the frequency ratio of each group of loads, and the application frequency of each group of loads; the output power of the three sets of load simulation devices (2) is realized by adjusting the angular velocity ω of the drive motor of the three sets of load simulation devices (2); S3. The orientation of the three sets of load simulation devices (2) is determined according to the collected environmental data; S4. The wind load Th, wave load F determined according to step S2 wave and the size of the extreme condition wave load F wave max and the azimuth of the installation of the three sets of load simulation devices (2) determined according to step S3, the load application time of each group of loads is determined according to the load frequency ratio of each group, the loading program of the wind turbine is set, the mass of the mass block (10) in the load simulation device, the diameter of the gear (11) and the gear rotation speed are determined, the force sensor is connected with the load simulation device (2), the cycle load is tested in advance to determine whether it meets the requirements, the load simulation device (2) and the force sensor are disconnected after the test is completed, the load simulation device (2) is fixed at the specified loading point position of the wind turbine model, the installation angle of the load simulation device (2) and the initial position of the gear in the device are adjusted, and the fastening degree of the transmission and the wind turbine tower body is checked to ensure that the force can be directly transmitted to the structure at the beginning of the test; S5. The laser vibration meter (9) is arranged outside the fan model, and the MEMS accelerometer is installed on each cyclic load simulation device for monitoring the structural acceleration of each part of the single-pile model tower body, so as to calculate the load condition; S6. After all the devices are connected, it is tested whether the laser vibration meter and the acceleration sensor are working normally, the wave-making flow function of the scouring environment simulation device is started to simulate the scouring condition, the power supply of the loading transmission motor is turned on, and the load simulation device applies cyclic loads to the single-pile model at different angles, so as to accurately simulate the multi-directional environmental load of the fan under the marine scouring environment.

6. The method of claim 5, wherein, The specific method of step S2 is as follows: S2-1. Determine the size of wind load Th: the environmental data of the wind turbine site selected by the test research is divided into four groups according to the wind speed, which are n1 data before the wind speed of the wind turbine cut-in wind speed; n2 data between the wind speed of the wind turbine cut-in wind speed to the rated wind speed; n3 data between the wind speed of the wind turbine rated wind speed to the cut-out wind speed; n4 data outside the wind speed exceeding the cut-out wind speed; The four groups of data are respectively calculated by the weighted average value of each wind speed according to the frequency ratio of each wind speed wherein a i represents the frequency of each wind speed, U i represents each wind speed value, which is then converted into wind load data by the following formula: where p a is the density of air, A R is the fan rotor swept area, C T is the thrust coefficient, calculated at constant power operation of the fan as where U R is the fan rated wind speed; S2-2. Determine wave load F wave The maximum value is calculated using the Morison wave equation, whose formula is as follows: where S is the average water depth at the site of the experimental study; D P is the diameter of the experimental study pile; p w is the density of water; C D and C M are the drag and inertia coefficients, respectively, which are conservatively taken as 1.0 and 2.0, respectively; and η is the sea surface elevation at the site of the experimental study, expressed as where H is the average wave height, T is the wind wave period, k is the wave number, and is calculated from the wave angular frequency ω k , ω k 2 = gk tanh(kS), where t is time and x is the horizontal distance from the wave to the pile. S2-3. Determine extreme condition wave load F wave max Size: Take the average wave height data value H collected from the environmental data of the actual operation of the wind turbine for 100 years or 50 years max , that is, the fifth group of load data, F is obtained according to the following formula wave max : S2-4. Calculate the frequency ratio of the five groups of loads: the five groups of loads include: n1 data before the wind speed is lower than the cut-in wind speed of the wind turbine, n2 data between the cut-in wind speed and the rated wind speed of the wind turbine, n3 data between the rated wind speed and the cut-out wind speed of the wind turbine, n4 data beyond the cut-out wind speed, and the average wave height data value H collected by the environmental data of the 100-year or 50-year environment of the actual operation of the wind turbine max ; The frequency ratio of each group of loads where q takes 1, 2, 3, 4, 5; since the fifth group of loads is the load in extreme case, it appears less in actual situation, so n5=5%∑n can be taken q where q takes 1, 2, 3, 4; S2-5. Let the mass of the attached gear mass (10) in the load simulation device (2) be m; the radius of the gear (11) be r; the angular velocity of the gear (11) be ω; then the cyclic load of the load simulation device (2) output to the wind turbine model is F=F 1y +F 2y =2mrω 2 sinθ, wherein F 1y , F 2y respectively represent the force of the two gears (11) on the wind turbine model in the y-axis, the force of the two gears (11) on the wind turbine model in the x-axis is equal in size and opposite in direction, and cancels out to zero, θ represents the angle between the connecting line of the mass and the center of the gear (11) and the x-axis, then the extreme value of the cyclic load is F max =F 1y max +F 2y max =2mrω 2 , the size of the cyclic load can be achieved by adjusting the transmission box (13) to adjust the angular velocity ω of the gear, ω is the frequency of the load application; let F max respectively equal to Th, F wave , F wave max and the product of the scale ratio a of the wind turbine model for the equivalent of the wind load Th, the wave load F wave and the extreme condition wave load F wave max ; the frequency of the application of the five groups of loads ω q is calculated by the formula , q takes 1, 2, 3, 4, 5.

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