An offshore wind turbine jacket foundation with adjustable natural frequency and motion damping and a control method

Abstract

The application discloses a kind of offshore wind turbine jacket foundation with adjustable natural frequency and motion damping and control method, including jacket, tuning liquid damper system, flow monitoring and control system and acceleration data acquisition and analysis system;Tuning liquid damper system includes central liquid storehouse and distributed liquid storehouse, central liquid storehouse is communicated with seawater, central liquid storehouse and distributed liquid storehouse are transported by pipeline with liquid, flow monitoring and control system obtains each liquid storehouse storage information by acquisition data, acceleration data acquisition and analysis system acquires acceleration data at key node of jacket foundation, based on the data obtained, control pump on each pipeline realizes the redistribution adjustment of the liquid volume and liquid level of each liquid storehouse of damper system in short time, adjust the mass distribution of jacket structure as a whole to adjust natural frequency and motion damping.The application has the advantages of convenient construction, convenient operation, control precision, and is suitable for long-term dynamic load as far sea wind turbine foundation form.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of offshore wind turbine foundation, in particular to an offshore wind turbine jacket foundation capable of adjusting inherent frequency and motion damping and a control method. BACKGROUND

[0002] With the development of large-scale and deep-sea offshore wind power, the jacket foundation has a broad application prospect as a wind turbine foundation form suitable for water depth of more than 50 m. However, the in-situ jacket foundation is prone to strong wind, wave, current and earthquake and other external dynamic loads. When the external dynamic load frequency is close to the inherent frequency of the wind turbine foundation, the wind turbine structure will produce large deformation response due to resonance, thereby affecting the normal operation and service life of the wind turbine. The tuned liquid damper is a system composed of a water tank and liquid therein, which can attenuate the vibration of the main structure through liquid inertia force and dynamic pressure difference, and has been preliminarily applied in the vibration control of high-rise structures such as chimney towers and wind turbine towers. However, the current tuned liquid damper is usually a closed water tank, so the liquid storage capacity and liquid level are relatively fixed, resulting in a narrow effective damping frequency range, which is difficult to adjust in real time according to the change of external load frequency. In addition, a few interconnected ballast tanks with adjustable liquid storage capacity are mainly used for floating wind turbine platforms, and there is no specific design method for the tuned liquid damper system for the jacket foundation with large foundation stiffness and mass. Therefore, designing a jacket foundation capable of adjusting inherent frequency and motion damping has important engineering application value for improving the operation stability and service life of offshore wind turbines.

[0003] The difficulty in design lies in how to arrange and design the liquid tank of the jacket damper system, and how to take relatively rapid and effective measures to adjust the inherent frequency of the foundation on the premise of real-time detection of the acceleration of the jacket nodes. This is the problem that the application focuses on solving. SUMMARY

[0004] The purpose of the application is to design a jacket foundation capable of adjusting inherent frequency and motion damping for offshore wind turbines and a control method. Through rational design of the damper system liquid tank and the control device, the arrangement and control scheme of the liquid tank are designed according to the deformation mode of the jacket foundation, so that the inherent frequency and motion damping of the foundation can be actively controlled and adjusted in real time.

[0005] The technical scheme of the application is as follows:

[0006] A jacket foundation capable of adjusting inherent frequency and motion damping for offshore wind turbines, comprising: a jacket, a tuned liquid damper system, a flow monitoring and control system and an acceleration data acquisition and analysis system.

[0007] The tuning liquid damper system comprises a central liquid tank installed on the bottom surface of the topside platform of the jacket, and a plurality of distributed liquid tanks arranged at the nodes of the jacket, the central liquid tank and the distributed liquid tanks are connected by pipes and communicate with seawater, each pipe is provided with a flow meter and the liquid is transported by a pump, the acceleration data acquisition and analysis system comprises an acceleration acquisition device and a data processing system, the acceleration acquisition device is arranged at the key nodes of the jacket foundation and transmits the collected data to the data processing system, the flow monitoring and control system comprises the flow meter, the pump, a data acquisition instrument and a liquid level meter data acquisition instrument arranged in each distributed liquid tank, which transmits the collected data to the data processing system, and controls the pump on each pipe according to the processing result of the data processing system, so as to realize the redistribution and adjustment of the seawater storage capacity and the liquid level in the central liquid tank and each distributed liquid tank, adjust the mass distribution of the jacket structure as a whole, and further realize the adjustment and control of the natural frequency and the motion damping of the structure.

[0008] Further, the distributed liquid tank is connected with interlayer liquid conveying pipes, interlayer backflow pipes and intralayer liquid conveying pipes on the side wall thereof, which are respectively used for connecting the lower distributed liquid tank, the upper distributed liquid tank and the distributed liquid tank in the same layer; the central liquid tank can directly extract seawater to complete liquid storage, and no backflow pipe is needed between the uppermost distributed liquid tank and the central liquid tank; the interlayer liquid conveying pipe of the lowermost distributed liquid tank is directly connected to seawater, so that the damper system can quickly discharge excess liquid.

[0009] Further, a filter grid is arranged in the central liquid tank to divide the space in the central liquid tank into two layers, an upper layer is a liquid storage chamber, and a lower layer is a sediment deposition chamber; the sediment deposition chamber is connected to seawater through a water pumping pipe, and the liquid storage chamber is connected to the distributed liquid tank through a water conveying pipe;

[0010] The central liquid tank pumps seawater through a pipe, separates the sediment and filters the liquid in the sediment deposition chamber, and injects the liquid into the liquid storage chamber; the uppermost distributed liquid tank is transported with liquid by the central liquid tank through a pipe, and when the liquid storage capacity demand is met, the excess liquid is transported to the lower distributed liquid tanks layer by layer through a pipe; the lowermost distributed liquid tank can discharge the excess liquid in the system back to the ocean through a pipe in addition to receiving the liquid from the upper distributed liquid tank; the distributed liquid tanks in the same layer are horizontally transported with liquid through intralayer liquid conveying pipes, and the liquid is backflowed and supplied through interlayer backflow pipes between adjacent two layers of distributed liquid tanks.

[0011] Further, the filter grid is fixed with sliding rails, and an M-shaped folding plate with holes is arranged in the liquid storage chamber, the M-shaped folding plate with holes is formed by a plurality of hole plates hinged in sequence by cylindrical hinges, and sliding blocks are arranged at both ends of the M-shaped folding plate with holes and are installed in the sliding rails and can only move along the sliding rails; waterproof rubber strips and a plurality of waterproof rubber protrusions are fixed on the filter grid; the bottom of the central liquid tank is a closable baffle, and the central liquid tank further comprises a central electric control system, the central electric control system controls the movement of the sliding blocks to fold or unfold the M-shaped folding plate with holes, and controls the opening and closing of the closable baffle; when the M-shaped folding plate with holes is unfolded, the holes in the M-shaped folding plate with holes are in one-to-one correspondence with the waterproof rubber protrusions and the waterproof rubber protrusions are embedded in the holes, and the waterproof rubber strips and the waterproof rubber protrusions completely isolate the liquid storage chamber and the sediment deposition chamber.

[0012] Further, when the capacity of the sediment deposition chamber is insufficient, the M-shaped folding plate with holes is controlled by the central electric control system to be unfolded on the filter grid, when the M-shaped folding plate with holes is completely unfolded, the waterproof rubber protrusions on the filter grid 21 are completely embedded in the holes of the M-shaped folding plate with holes, and the waterproof rubber strips and the waterproof rubber protrusions completely isolate the liquid storage chamber and the sediment deposition chamber, that is, the filtered liquid is completely sealed in the liquid storage chamber; the central electric control system opens the closable baffle at the bottom of the central liquid tank to discharge the sediment back into seawater, after the sediment is discharged into seawater, the central electric control system closes the closable baffle and retracts the M-shaped folding plate with holes.

[0013] Further, different direction damping nets are installed in the distributed liquid tanks, and the M-shaped folding plate with holes in the folded state and the damping nets are used to increase the resistance generated by liquid sloshing when the structure vibrates.

[0014] Further, stiffening plates and horizontal stiffening bars are additionally welded at the jacket nodes for installing and fixing the distributed liquid tanks.

[0015] Further, the data acquisition instrument and the data processing system are integrated into the central control system in the offshore wind turbine cabin, the data acquisition instrument acquires data of the flow meters and the liquid level meters, calculates the current liquid storage capacity of each liquid tank to obtain the damping distribution, the data processing system combines the acceleration parameters measured by each node of the jacket, obtains the optimal solution of adjusting the natural frequency and damping of the structure based on the current natural frequency of the jacket and the damping distribution, and transmits the required liquid capacity of each liquid tank to the flow monitoring and control system to control the pumping and discharging of each water pump, and completes the redistribution of the mass and damping of the tuned liquid damper system.

[0016] The above-mentioned offshore wind turbine jacket foundation with adjustable natural frequency and motion damping control method, the foundation adjusts the natural frequency and motion damping of the structure in real time, and the control method comprises the following steps:

[0017] The central liquid tank extracts seawater, the seawater enters the liquid storage chamber after being filtered by the filter grid, and the silt in the seawater is left in the silt deposition chamber after being separated by standing; when the liquid storage capacity of the central liquid tank reaches the required value, the excess liquid flows into the lower distributed liquid tank through the water pipeline layer by layer; when the liquid in each liquid tank is filled, the flow monitoring and control system calculates the current liquid storage capacity of each liquid tank according to the flow data of each liquid channel measured by each flow meter, and adjusts the liquid mass distribution ratio in each liquid tank according to the overall mass and inherent frequency of the guide pipe frame, so that the ratio of the inherent frequency of the tuned liquid damper to the overall first-order inherent frequency of the guide pipe frame is 0.9-1.1, and the ratio of the total mass of the damper to the overall mass of the guide pipe frame is 1.7%-2.3%;

[0018] When the guide pipe frame structure is subjected to external dynamic load and generates vibration response, the acceleration data acquisition and analysis system acquires acceleration data at the top of the guide pipe frame and at key nodes, so as to calculate the current external load frequency; in combination with the inherent frequency and damping distribution of the current guide pipe frame structure, the optimal solution of the adjusted inherent frequency and damping distribution of the guide pipe frame is obtained, and the required liquid storage capacity reference value of each liquid tank is transmitted to the flow monitoring and control system.

[0019] The flow monitoring and control system controls each water pump to complete the liquid pumping and discharging activity according to the current liquid storage capacity and the required liquid storage capacity reference value of each liquid tank, so that the central liquid tank and each distributed liquid tank complete the liquid storage capacity redistribution adjustment, thereby timely reducing the influence of external dynamic load on the overall stability of the structure.

[0020] The beneficial effects of the present application are as follows:

[0021] The present application realizes the pretreatment, storage and transportation of seawater through the central liquid tank, avoiding the inconvenience caused by pre-filling of closed damping liquid to construction and subsequent operation and maintenance. The different types of liquid conveying pipelines between the liquid tanks can complete the mass and damping redistribution adjustment of the damper system in a short time. The flow control and monitoring system and the acceleration output acquisition system work cooperatively to monitor and adjust the motion damping at each node and the overall inherent frequency of the guide pipe frame in real time according to the node acceleration and vibration frequency of the current guide pipe frame structure, so as to minimize the influence of external load frequency change on the stability of the structure. The guide pipe frame base material is environmentally friendly, convenient for construction and operation, and the control is accurate. BRIEF DESCRIPTION OF DRAWINGS

[0022] The drawings accompanying the specification of this application form a part thereof, serve to provide further understanding of the present application, and together with the description of the exemplary embodiments of the present application and explanations thereof, make an explanation of the present application complete, and do not constitute an improper limitation of the present application. In the drawings:

[0023] In the drawings:

[0024] Figure 1Fig. 1 is a schematic diagram of the overall structure of a jacket foundation for offshore wind turbines according to an embodiment of the present application;

[0025] Figure 2 Fig. 2 is a schematic diagram of the reinforcement of the nodes of the jacket and the arrangement of the liquid chambers according to an embodiment of the present application;

[0026] Figure 3 Fig. 3 is a schematic diagram of the structure of the central liquid chamber according to an embodiment of the present application.

[0027] Figure 4 Fig. 4 is a schematic diagram of the structure of the central liquid chamber according to an embodiment of the present application.

[0028] Figure 5 Fig. 5 is a schematic diagram of the structure of the distributed liquid chamber according to an embodiment of the present application.

[0029] Legend of the figures:

[0030] 1 - wind turbine tower and upper support; 2 - working platform;

[0031] 3 - jacket; 4 - central liquid chamber;

[0032] 5 - distributed liquid chamber; 6 - central pumping pipe;

[0033] 7 - central water delivery pipe; 8 - interlayer water delivery pipe;

[0034] 9 - interlayer backflow pipe; 10 - intralayer water delivery pipe;

[0035] 11 - flow meter; 12 - stiffening plate;

[0036] 13 - transverse stiffening rod; 14 - liquid storage chamber;

[0037] 15 - silt deposition chamber; 16 - M-shaped perforated folding plate;

[0038] 17 - cylindrical hinge; 18 - drainage hole;

[0039] 19 - sliding block; 20 - sliding rail;

[0040] 21 - filter grid; 22 - openable lower baffle;

[0041] 23 - waterproof rubber joint; 24 - water pump;

[0042] 25 - three-axis accelerometer; 26 - waterproof rubber protrusion;

[0043] 27 - waterproof rubber strip; 28 - damping net;

[0044] 29 - liquid level meter. DETAILED DESCRIPTION

[0045] The embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0046] The jacket foundation form of the present application can adjust the natural frequency and motion damping, which comprises a jacket structure, a tuned liquid damper system, a flow control and monitoring system and an acceleration data acquisition and analysis system.

[0047] The jacket structure is the main part of the foundation form, which is mainly made of steel. Unlike the jacket foundation commonly used in engineering, the jacket structure is welded with stiffened plates and transverse stiffened bars at the jacket joints to avoid local buckling of the jacket structure caused by high liquid storage capacity or large load of the liquid bin, thus meeting the requirements of convenience for liquid bin installation and structural safety. The liquid bin is fixed on the stiffened plate and is firmly connected with the stiffened plate and the transverse stiffened bars of the jacket through welding and screw fixation and the like.

[0048] The tuned liquid damper system is the core part for adjusting the natural frequency and motion damping of the foundation. The tuned liquid damper system is composed of a central liquid bin installed at the bottom of the working platform, a plurality of distributed liquid bins arranged at the jacket joints and liquid conveying pipelines between the liquid bins. The central liquid bin sucks seawater through the pipeline and completes sand separation and liquid filtration in the sand deposition chamber, and then injects the liquid required by the damper into the liquid storage chamber of the central liquid bin. The uppermost distributed liquid bin is supplied with liquid by the central liquid bin through the pipeline, and when the liquid storage capacity requirement is met, the excess liquid is conveyed to the next layer of distributed liquid bin through the pipeline. The lowermost liquid bin, in addition to receiving liquid from the upper liquid bin, can also discharge the excess liquid in the system back to the ocean through the pipeline. The liquid can be horizontally conveyed between the distributed liquid bins in the same layer through the intra-layer liquid conveying pipe, and the liquid can be returned and supplemented between the upper and lower liquid bins through the inter-layer return pipe, so as to redistribute and adjust the liquid storage capacity and liquid level of each liquid bin in the damper system in a short time. By changing the liquid storage capacity in each liquid bin, the mass distribution of the jacket structure as a whole can be adjusted, and thus the adjustment and control of the natural frequency and motion damping of the structure can be realized. The liquid in the liquid bin is usually not full, and the inertia force and dynamic pressure difference of the liquid during structure vibration, combined with the damping net arranged inside the liquid bin, consume the vibration energy to achieve the damping effect. By adjusting and controlling the liquid storage capacity in each liquid bin, the motion damping at the joints of the jacket structure can be changed.

[0049] The flow control and monitoring system includes a liquid level meter, a flow meter, a water pump and a data acquisition instrument. The liquid level meter is arranged in each distributed liquid tank to measure the real-time liquid level height in the tank, and then used to calculate the mass distribution and motion damping of each liquid tank. The flow meter is arranged on the liquid delivery pipeline to measure the amount of liquid flowing into and out of each liquid tank; according to an example of the present invention, the water pump can be arranged at the end of the liquid tank extraction and infusion pipeline to pump liquid into each liquid tank; the data acquisition instrument can be integrated into the central control system in the cabin at the top of the fan, and the current liquid storage volume in each liquid tank can be calculated based on the data of each flow meter and liquid level meter. The flow control and monitoring system can also include an integrated control program for the operation of each water pump, which controls the pumping and discharge volume of the water pump based on the reference amount of the liquid level demand, infusion and discharge parameters of each liquid tank transmitted by the acceleration data acquisition and analysis system, and can also be calibrated in combination with the flow meter monitoring data.

[0050] The acceleration data acquisition and analysis system consists of an acceleration acquisition device, such as a triaxial accelerometer, and an acceleration data processing system. Several triaxial accelerometers are arranged at the jacket nodes and on the outer walls of each liquid tank; the acceleration data processing system can be integrated into the central control system within the wind turbine's top nacelle. The acceleration data processing system calculates the overall vibration frequency of the jacket structure based on the jacket node accelerations collected by each accelerometer. It then calculates the optimal solution for adjusting the mass distribution of the liquid tanks based on pre-set adjustment rules. Combined with the motion damping distribution and control indicators of each node, the system transmits the infusion and discharge volumes of each liquid tank to the flow control and monitoring system, thereby achieving real-time adjustment of the jacket foundation's natural frequency and motion damping.

[0051] like Figures 1-5 This is a specific example of the present invention, specifically:

[0052] Figure 1 shows an overall schematic diagram of the jacket foundation in an example of the present invention, Figure 2 Shows the jacket local node reinforcement scheme and distributed liquid tank installation diagram, Figure 3 and Figure 4 The internal structure plane and three-dimensional schematic diagram of the central liquid tank are shown respectively. Figure 5 The internal structure of the distributed liquid tank is shown in the figure. As shown in the figure, this example provides an offshore wind power jacket foundation with adjustable structural natural frequency and motion damping:

[0053] Figure 1The illustrated jacket structure has the basic structural elements of an engineering jacket foundation, including the superstructure 1, working platform 2 and jacket body 3. After the completion of the basic structure of the jacket, the central liquid tank 4 is installed on the bottom surface of the working platform by hoisting and transporting, and the central water pumping pipe 6 and the central water conveying pipe 7 are installed on the side wall of the central liquid tank. Before the installation of the distributed liquid tank 5, the jacket node is welded Figure 2 The illustrated stiffening plate 12 and transverse stiffening rod 13 ensure that the jacket node will not locally buckle due to the gravity load of the liquid tank. After the installation of the distributed liquid tank 5, the interlayer liquid conveying pipe 8, the interlayer backflow pipe 9 and the intra-layer liquid conveying pipe 10 are sequentially connected on the side wall thereof, respectively used for connecting the lower distributed liquid tank, the upper distributed liquid tank and the distributed liquid tank in the same layer. Since the central liquid tank 4 can directly extract seawater to complete the liquid storage, the backflow pipe 9 does not need to be arranged between the uppermost distributed liquid tank 5 and the central liquid tank 4. The interlayer liquid conveying pipe 8 of the lowermost distributed liquid tank 5 is directly connected to the seawater, facilitating the damper system to quickly discharge excess liquid.

[0054] Figure 3 and Figure 4The central liquid tank 4 mainly includes a silt deposition chamber 15, a liquid storage chamber 14, an M-shaped folding plate with holes 16, a sliding block 19, a sliding rail 20, a filter grid 21, and an open-close lower baffle 22. The M-shaped folding plate with holes 16 and the open-close lower baffle 22 are both controlled by a central control system. After the central liquid tank 4 directly extracts seawater from the marine environment, the seawater is filtered by the filter grid 21 and then enters the liquid storage chamber 14, and the silt and sundries are deposited in the silt deposition chamber 15 after being at rest, thereby avoiding the blockage of the liquid conveying pipeline caused by the mixing of silt into the liquid. When the capacity of the silt deposition chamber 15 is insufficient, the M-shaped folding plate with holes 16 is controlled by the central control system to be stretched and laid flat on the filter grid 21, and the folding and stretching actions of the folding plate can be realized through the cylindrical hinge 17, the sliding block 19, and the sliding rail 20. When the folding plate is completely laid flat, the waterproof rubber protrusions pre-installed on the filter grid 21 will be completely embedded in the drainage holes 18 of the folding plate, and in combination with the waterproof rubber strips 27 pre-installed on the filter grid 21, the folding plate and the filter grid will completely isolate the liquid storage chamber 14 and the silt deposition chamber 15 after being laid flat, that is, the filtered liquid is completely sealed in the liquid storage chamber. The silt can be discharged back into seawater by opening the open-close lower baffle 22 at the bottom of the central liquid tank 4 through the central control system. After the silt is discharged into seawater, the central control system closes the lower baffle 22 and retracts the M-shaped folding plate with holes 16, thereby facilitating the completion of the next liquid extraction activity. In addition to the function of sealing the liquid storage chamber 14, the M-shaped folding plate 16 further increases the motion damping of the central liquid storage chamber when the liquid flows through the drainage holes 18 of the folding plate and is resisted by the structure. To ensure good waterproof sealing of the device, waterproof rubber strips 27 are installed at the ends of the sliding rail 20, and waterproof rubber joints 23 are installed at the opening of the open-close lower baffle 22. The folding and stretching control method of the M-shaped folding plate with holes 16 and the structure and control method of the open-close lower baffle 22 are not limited in the present application, and according to a specific example of the present application, the following method can be used to realize the opening and closing of the M-shaped folding plate with holes 16: a track is arranged on the contact part between the bottom of the sliding block 19 and the sliding rail 20, a drive motor is installed inside the sliding block 19, the sliding block 19 moves forward and backward by controlling the forward (reverse) transmission of the track, and then the M-shaped folding plate with holes 16 is opened and closed; a rotating motor is built-in the rotating shaft of the open-close lower baffle 22, and the baffle is opened and closed by controlling the clockwise (counterclockwise) rotation of the motor.

[0055] Figure 5The distributed liquid tank 5 is installed at the key node of the jacket structure, and the distributed liquid tank needs to be installed at the same height (same layer) jacket node. The liquid transfer between the liquid tanks in the same layer and different layers is completed through the interlayer liquid transfer pipeline 8, the interlayer backflow pipeline 9 and the intra-layer liquid transfer pipeline 10. The distributed liquid tank 5 is internally provided with a damping net 28 in different directions, which can provide additional resistance when the liquid in the tank shakes, thereby increasing the energy consumption of the damper; the liquid level meter 29 is installed in each liquid tank to measure the liquid level in the tank in real time. By changing the mass of the liquid tank body, the natural frequency of the liquid tank is changed, thereby realizing the effect of tuning the damper.

[0056] After the basic construction of the jacket and the liquid damper system is completed, the flow monitoring and control system and the acceleration data acquisition and analysis system can realize real-time adjustment of the natural frequency and motion damping of the jacket foundation:

[0057] First, the central liquid tank 4 draws seawater through the water pump 24 and the central water pumping pipeline 6. The seawater is filtered through the filter grid 20 and then enters the liquid storage chamber 14. The sand in the seawater is separated by standing and remains in the sand deposition chamber 15. When the liquid storage capacity of the central liquid tank reaches the required value, the excess liquid flows into the distributed liquid tank 5 layer by layer through the central water transfer pipeline 7. When each liquid tank is filled with liquid, the flow monitoring and control system calculates the current liquid storage capacity of each liquid tank according to the flow data measured by the flow meter 11 of each liquid transfer channel, and adjusts the liquid mass distribution ratio in each liquid tank according to the overall mass and natural frequency of the jacket. When the ratio of the tuned liquid damper natural frequency to the overall first-order natural frequency of the jacket is 0.9-1.1, and the ratio of the total mass of the damper to the overall mass of the jacket is 1.7%-2.3%, the damping effect of the damper system is best. The overall first-order natural frequency of the jacket can be calculated based on the frequency based on numerical simulation software such as ANSYS (for reference, H-type offshore dynamic derrick dynamic performance analysis [J]. Petroleum field machinery, 2007), and the natural frequency of the liquid tank can be calculated based on the following formula:

[0058]

[0059] Where H is the liquid height in the liquid tank, L is the distance between the front and rear inner walls of the liquid tank, m is a constant value of 1, g is the acceleration of gravity, and π is the circular constant.

[0060] Second, when the jacket structure is subjected to external dynamic load and generates vibration response, the acceleration data acquisition and analysis system collects acceleration data of the top of the jacket and key nodes through the three-axis accelerometer 25 installed on the outer wall of the liquid tank, so as to calculate the current external load frequency. The acceleration analysis system determines the minimum number of liquid tanks that need to be adjusted and the shortest drainage path of adjusting the liquid storage capacity of each liquid tank based on the current natural frequency of the jacket structure and the motion damping distribution of each node, the external load frequency and its distribution data, so as to determine the optimal solution of adjusting the natural frequency and damping distribution of the current jacket, and transmit the required liquid storage capacity reference value of each liquid tank to the flow monitoring and control system.

[0061] Third, after receiving the required liquid storage capacity reference value of each liquid tank, the flow monitoring and control system controls the water pump 24 to complete the liquid pumping and draining activity through the electric control system, and the liquid in each distributed liquid tank is redistributed and adjusted in the shortest time through the interlayer liquid conveying pipeline 8, the interlayer backflow pipeline 9 and the intra-layer liquid conveying pipeline 10, so as to timely reduce the influence of external dynamic load on the overall stability of the structure.

[0062] The above only describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. An offshore wind turbine jacket foundation with adjustable natural frequency and motion damping, characterized in that: include: Jacket, tuned liquid damper system, flow monitoring and control system and acceleration data acquisition and analysis system; The tuned liquid damper system includes a central liquid tank installed on the bottom surface of the working platform at the top of the jacket and several distributed liquid tanks arranged at the nodes of the jacket. The central liquid tank and the distributed liquid tanks are connected by pipelines and communicate with seawater. Each pipeline is equipped with a flow meter and controls liquid transportation through a pump. The acceleration data acquisition and analysis system includes an acceleration acquisition device and a data processing system. The acceleration acquisition device is arranged at a key node of the jacket foundation and transmits the collected data to the data processing system. The flow monitoring and control system includes the flow meter and pump, as well as a data acquisition instrument and a liquid level gauge arranged in each distributed liquid tank. The data acquisition instrument transmits the collected data to the data processing system. The pumps on each pipeline are controlled according to the processing results of the data processing system to achieve redistribution and adjustment of the seawater storage volume and liquid level in the central liquid tank and each distributed liquid tank, adjust the mass distribution of the entire jacket structure, and thereby achieve adjustment and control of the structural natural frequency and motion damping; The distributed liquid silos are connected to their side walls with interlayer liquid delivery pipes, interlayer return pipes, and intralayer liquid delivery pipes, which are respectively used to connect the distributed liquid silos on the lower layer, the distributed liquid silos on the upper layer, and the distributed liquid silos on the same layer. The central liquid silo can directly draw seawater to complete liquid storage, and no return pipe is required between the uppermost distributed liquid silo and the central liquid silo. The interlayer liquid delivery pipes of the lowermost distributed liquid silo are directly connected to the seawater, which facilitates the damper system to quickly discharge excess liquid. The central liquid tank is provided with a filter grid to divide the space inside the central liquid tank into two layers, the upper layer is a liquid storage chamber, and the lower layer is a sediment deposition chamber; the sediment deposition chamber is connected to seawater through a pumping pipe, and the liquid storage chamber is connected to the distributed liquid tank through a water supply pipe; The central liquid tank draws seawater through a pipeline, completes sediment separation and liquid filtration in the sedimentation chamber, and injects the liquid into the liquid storage chamber; the top distributed liquid tank is transported by the central liquid tank through a pipeline, and when the liquid storage capacity requirement is met, the excess liquid is transported down layer by layer through the pipeline to the distributed liquid tanks on each layer below; In addition to receiving liquid from the upper distributed liquid tanks, the bottom distributed liquid tank can also discharge excess liquid in the system back to the ocean through pipes. Distributed liquid tanks on the same layer are connected by intra-layer liquid transfer pipes for lateral liquid transportation, and adjacent distributed liquid tanks are connected by inter-layer return pipes for liquid reflux. A slide rail is fixed on the filter grille, and an M-shaped perforated folding plate is also provided in the liquid storage chamber. The M-shaped perforated folding plate is formed by a number of perforated plates hinged in sequence through cylindrical hinges. Sliders are provided at both ends of the M-shaped perforated folding plate. The sliders are installed in the slide rails and can only move along the slide rails; a waterproof rubber strip and a number of waterproof rubber protrusions are fixed on the filter grille; the bottom of the central liquid tank is an opening and closing baffle, and the central liquid tank also includes a central electronic control system, which controls the movement of the slider so that the M-shaped perforated folding plate is folded or unfolded and laid flat, and controls the opening and closing of the opening and closing baffle. When the M-shaped perforated folding plate is unfolded and laid flat, the hole positions on it correspond exactly to the waterproof rubber protrusions and the waterproof rubber protrusions are embedded in the holes, and together with the waterproof rubber strips, the liquid storage chamber is completely isolated from the sedimentation chamber.

2. The offshore wind turbine jacket foundation with adjustable natural frequency and motion damping according to claim 1 is characterized in that: When the capacity of the sediment deposition chamber is insufficient, the central electronic control system controls the M-shaped folding plate with holes to stretch and lay flat on the filter grille. When the M-shaped folding plate with holes is completely laid flat, the waterproof rubber protrusions on the filter grille will be completely embedded in the holes of the M-shaped folding plate with holes, and together with the waterproof rubber strips, completely isolate the liquid storage chamber and the sediment deposition chamber, that is, the filtered liquid is completely enclosed in the liquid storage chamber; the central electronic control system opens the opening and closing baffle at the bottom of the central liquid tank to discharge the sediment back into the sea. After the sediment is discharged into the sea, the central electronic control system closes the opening and closing baffle and retracts the M-shaped folding plate with holes.

3. The offshore wind turbine jacket foundation with adjustable natural frequency and motion damping according to claim 1 is characterized in that: Damping nets in different directions are installed in the distributed liquid tank. The M-shaped perforated folding plate and the damping net in the folded state are used to increase the resistance generated by liquid sloshing when the structure vibrates.

4. The offshore wind turbine jacket foundation with adjustable natural frequency and motion damping according to claim 1 is characterized in that: Stiffening plates and horizontal stiffening rods are additionally welded at the nodes of the jacket for installing and fixing the distributed liquid tank.

5. The offshore wind turbine jacket foundation with adjustable natural frequency and motion damping according to claim 1 is characterized in that: The data acquisition instrument and data processing system are both integrated into the central control system in the offshore wind turbine cabin. The data acquisition instrument obtains data from each flow meter and liquid level gauge, and calculates the current liquid storage volume of each liquid tank to obtain the damping distribution. The data processing system combines the acceleration parameters measured at each node of the jacket and obtains the optimal solution for adjusting the structural natural frequency and damping based on the current jacket natural frequency and damping distribution. The adjusted liquid volume required for each liquid tank is transmitted to the flow monitoring and control system to control the pumping and discharge of each water pump, thereby completing the mass and damping redistribution of the tuned liquid damper system.

6. The control method for an offshore wind turbine jacket foundation with adjustable natural frequency and motion damping according to any one of claims 1 to 5, characterized in that: The foundation adjusts the structural natural frequency and motion damping in real time, and the control method includes the following: The central liquid tank draws seawater, which is filtered through a filter grid before entering the liquid storage chamber. Sediment in the seawater is then statically separated and retained in the sediment deposition chamber. When the central liquid tank reaches the required liquid volume, excess liquid flows layer by layer through a water pipeline into the distributed liquid tanks below. As each tank is filled, the flow monitoring and control system determines the current liquid volume in each tank based on data measured by each flow meter and level gauge, and adjusts the liquid mass distribution ratio in each tank based on the overall mass and natural frequency of the jacket, so as to maintain a ratio of the natural frequency of the tuned liquid damper to the overall first-order natural frequency of the jacket within a range of 0.9 to 1.1, and a ratio of the total mass of the damper to the overall mass of the jacket within a range of 1.7% to 2.3%. When the jacket structure is subjected to external dynamic loads and generates a vibration response, the acceleration data acquisition and analysis system collects acceleration data at the jacket top and key nodes to calculate the current external load frequency. Combined with the current jacket structure's natural frequency and damping distribution, the optimal solution for the adjusted jacket natural frequency and damping distribution is obtained, and a reference value for the required liquid storage volume of each liquid tank is transmitted to the flow monitoring and control system. The flow monitoring and control system controls each water pump to complete the liquid pumping and drainage activities according to the current liquid storage volume of each liquid tank and the required liquid storage volume reference value, and completes the liquid storage volume redistribution adjustment of the central liquid tank and each distributed liquid tank, thereby timely reducing the impact of external dynamic loads on the overall stability of the structure.

7. The control method for an offshore wind turbine jacket foundation with adjustable natural frequency and motion damping according to claim 6, characterized in that: The external load frequency and its distribution data are combined to determine the minimum number of liquid tanks that need to be mobilized, as well as the shortest pumping and drainage paths to adjust the liquid storage volume in each tank, thereby determining the optimal solution for adjusting the current jacket natural frequency and damping distribution.

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