Variable cross-section column type offshore platform foundation and resonance suppression control system

Abstract

The application provides a variable cross-section column type offshore platform foundation and a resonance suppression control system, and belongs to the technical field of ocean engineering. The application solves the problem of how to improve the seakeeping performance of an offshore platform foundation by adjusting the cross-sectional area of a waterline contact section while maintaining stability. The application comprises multiple columns and a buoyancy adjusting device. Each column is provided with a contact section intersecting a waterline. The contact section is divided into an inner part and an outer part. The inner part is a central column with a smaller radius than the column. The outer part is a plurality of square boxes arranged uniformly in a circumferential direction. The square boxes are connected to the central column through an expansion mechanism and can move in a horizontal direction. The buoyancy adjusting device controls the lifting of the plurality of square boxes to ensure that the waterline is located in the contact section. The application is mainly used for achieving the best seakeeping effect of an offshore platform.

Description

Technical Field

[0001] This invention belongs to the field of marine engineering technology, and in particular relates to a variable cross-section column-type offshore platform foundation and resonance suppression control system. Background Technology

[0002] In recent years, with the increasing consumption of fossil fuels, the demand for clean energy has been gradually increasing. Offshore platforms, due to their unique geographical advantages and abundant resources, can support the production of various clean energy sources, such as offshore wind power, offshore photovoltaics, ocean thermal energy conversion, and hydrogen production. Offshore platforms offer vast development space for clean energy production and have great potential.

[0003] However, offshore platforms typically face challenges such as large wave loads and significant dynamic response in practical applications, which in turn affect system safety and energy production efficiency. Adjusting the cross-sectional area of ​​the waterline contact section can improve the seakeeping of offshore platforms, but this change also alters the platform's stability. Therefore, improving the seakeeping of offshore platforms while maintaining stability has become a crucial research topic, aiming to promote the further development and application of offshore platform technology. Summary of the Invention

[0004] In view of this, to address the problem of how to improve the seakeeping performance of offshore platform foundations while maintaining stability by adjusting the cross-sectional area of ​​the waterline contact section, this invention proposes a variable cross-section column-type offshore platform foundation and a resonance suppression control system. The cross-sectional area of ​​the platform foundation's contact section with the waterline is adjustable to meet the seakeeping requirements of offshore platforms under various sea conditions. The design of this device fully considers the needs of different types and sizes of offshore floating platforms, exhibiting good adaptability. The platform foundation is equipped with a resonance suppression control system that can adjust the size of the cross-sectional area of ​​the column-waterline contact section in real time according to changes in the marine environment, thus skewing the platform's natural period from the wave period, avoiding resonance, and effectively reducing the wave load on the offshore platform foundation and the dynamic response of the offshore platform to achieve optimal seakeeping performance.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a variable cross-section column-type offshore platform foundation, comprising multiple columns and a buoyancy adjustment device;

[0006] Each column is equipped with a contact section that intersects with the water surface line. The contact section is divided into inner and outer parts. The inner part is a central column with a radius smaller than that of the column. The outer part consists of multiple square boxes evenly arranged in the circumference. The square boxes are connected to the central column through a telescopic mechanism and can move horizontally.

[0007] The buoyancy adjustment device controls the raising and lowering of multiple columns to ensure that the water level is within the contact section.

[0008] Furthermore, the telescopic mechanism is driven by a hydraulic device and has a nitrogen-filled chamber on its outer side.

[0009] Furthermore, the telescopic mechanism is a folding arm, with one end of the folding arm hinged to the central column and the other end hinged to the square box.

[0010] Furthermore, the bottom surface of the column above the central column is provided with multiple limiting grooves in the radial direction, and the top of the square box is provided with a round pin. The limiting grooves and the round pin cooperate to ensure that the square box moves strictly in the radial direction when it moves horizontally.

[0011] Furthermore, the buoyancy adjustment device is a pontoon, which is a hollow column structure with a dynamic ballast tank inside. There are four columns arranged in a square at the four corners, and the bottom is fixed by two alternately arranged cross braces and two pontoons.

[0012] Furthermore, the equivalent radius range for adjusting the horizontal movement of the telescopic mechanism is 70%-120% of the column radius. When the telescopic mechanism is fully retracted, the overall cross-sectional profile of the multiple square boxes is annular.

[0013] Furthermore, 12 square boxes are evenly arranged around the outer perimeter of each column.

[0014] Furthermore, the central column is made of corrosion-resistant reinforced structural steel, and the square box is made of hollow glass microspheres and resin composite molding.

[0015] A resonance suppression control system for the above-mentioned variable cross-section column-type offshore platform foundation includes a wave detection module, a spectrum analysis module, a telescopic mechanism control module, and an active vibration damping control module.

[0016] The wave detection module is used to collect wave height time-series data around the platform foundation in real time and transmit it to the spectrum analysis module.

[0017] The spectrum analysis module is used to calculate the current wave energy density spectrum and extract the main frequency based on the wave height time series data. The main frequency is defined as the frequency f0 corresponding to the peak value of the energy spectrum. The spectrum analysis module transmits f0 to the active vibration control module in real time.

[0018] The telescopic mechanism control module transmits the cross-sectional area S of the platform's waterline contact section to the active vibration damping control module in real time, and drives the telescopic mechanism to extend or retract according to the control commands of the active vibration damping control module, so that the cross-sectional area S of the platform's waterline contact section is within a preset range [S]. min S max Continuously adjustable within;

[0019] The active vibration damping control module incorporates a digital twin model of the dynamic response of the offshore hydrogen production platform. Based on the real-time input f0 and the cross-sectional area S of the platform's waterline contact section, it dynamically calculates the platform's natural period T. s And generate control commands and send them to the telescopic mechanism control module, so that T s satisfy:

[0020] |1 / T s -f0|≥Δ

[0021] Where Δ is the frequency isolation margin set according to the platform structure safety factor.

[0022] Furthermore, the wave detection module includes at least two sets of wave height meters deployed circumferentially along the platform foundation on the coast. The wave height meter detection area is a radius of 200-500 meters around the platform foundation. The spectrum analysis module is connected to the embedded processor of the wave height meter and performs segmented windowing processing and calculation on the wave height data based on the improved Welch algorithm.

[0023] Compared with existing technologies, the beneficial effects of the variable cross-section column-type offshore platform foundation and resonance suppression control system described in this invention are:

[0024] 1. The present invention enables the adjustment of the cross-sectional area of ​​the waterline contact section of the offshore platform foundation, thereby improving the seakeeping performance of the offshore platform foundation to meet the seakeeping requirements of the offshore platform under various sea conditions.

[0025] 2. The offshore platform foundation of this invention is equipped with a resonance suppression control system, which can adjust the size of the cross-sectional area of ​​the column contact section in real time according to changes in the marine environment, and avoid the natural period being the same as the frequency when the wave energy is at its maximum, which would cause resonance and have an adverse effect on the stability of the platform. It effectively reduces the wave load and dynamic response of the offshore platform foundation, improves the wave resistance performance of the offshore platform foundation, reduces the dependence on professional technicians, and enables the offshore platform foundation to adapt to harsh marine environments.

[0026] 3. During the hoisting process, offshore platforms are easily affected by wind and waves due to their small draft and may sway. The present invention can increase the cross-sectional area of ​​the column contact section of the offshore platform foundation during the hoisting process, which will increase the initial stability of the offshore platform and increase its restoring force coefficient in the heave and roll degrees of freedom, thereby helping the offshore platform to return to its original static state.

[0027] 4. In this invention, the seawater within the gap between the box and the central column forms a restricted flow under wave action, generating viscous drag, which can dissipate some wave energy and reduce the overall dynamic response of the platform. This effect is similar to the design of anti-roll fins or damping chambers on ships, which helps to suppress roll and heave motions.

[0028] 5. The invention has a simple structure, which reduces the overall complexity. Considering the various working conditions in the actual marine environment, the invention adopts an easy-to-disassemble modular design, with each box being independent of the others, making future cleaning and maintenance work more convenient and faster. Attached Figure Description

[0029] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0030] Figure 1 This is a schematic diagram of the main structure of the column of the present invention;

[0031] Figure 2 This is a front view of the contact section of the square box of the present invention when it is in a fully retracted state;

[0032] Figure 3 This is a top view of the contact section of the square box of the present invention when it is in a fully retracted state;

[0033] Figure 4 This is a front view of the contact section when the square box of the present invention is moved to a position with the same equivalent radius as the column;

[0034] Figure 5 This is a top view of the contact section when the square box of the present invention is moved to a position with the same equivalent radius as the column;

[0035] Figure 6 This is a front view of the contact section of the square box of the present invention when it is in the fully extended state;

[0036] Figure 7 This is a top view of the contact section of the square box of the present invention when it is in the fully extended state;

[0037] Figure 8 This is a schematic diagram of the limiting groove structure of the present invention;

[0038] Figure 9 This is a schematic diagram of the circular pin structure of the present invention;

[0039] Figure 10 This is a diagram showing the change in the positional relationship between the limiting groove and the round pin when the square box of the present invention moves from the fully retracted position to the fully extended position. In the diagram, (a) indicates that the square box is in the fully retracted position, (b) indicates that the square box has moved to the edge of the column, and (c) indicates that the square box is in the fully extended position.

[0040] Figure 11 This is a schematic diagram of the cross brace and pontoon structure of the present invention;

[0041] Figure 12 This is a schematic diagram of the resonance suppression control system of the present invention;

[0042] Figure 13 This is a graph showing the relationship between wave spectral density and frequency in a certain sea area.

[0043] In the diagram: 1-Column; 2-Float; 11-Contact section; 12-Horizontal brace; 111-Central column; 112-Square box; 113-Telescopic mechanism; 114-Limiting groove; 115-Round pin;

[0044] 101-Wave detection module; 102-Spectrum analysis module; 103-Telescopic mechanism control module; 104-Active vibration damping control module. Detailed Implementation

[0045] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other, and the described embodiments are only some embodiments of the present invention, not all embodiments.

[0046] I. Detailed Implementation Method 1, see [link / reference] Figure 1-13 This embodiment describes a variable cross-section column-type offshore platform foundation, which includes multiple columns 1 and a buoyancy adjustment device.

[0047] Each column 1 has a contact section 11 that intersects the waterline. The contact section 11 is divided into inner and outer parts: the inner part is a central column 111 with a radius smaller than the column's radius, and the outer part consists of multiple circumferentially evenly arranged square boxes 112. The square boxes 112 are connected to the central column 111 via a telescopic mechanism 113, allowing them to extend and retract horizontally. The number, size, and layout of the columns 1 are designed according to the dimensions and shape of the offshore platform foundation. The seawater within the gap between the square boxes 112 and the central column 111 forms a restricted flow under wave action, generating viscous drag, which can dissipate some wave energy and reduce the overall dynamic response of the offshore platform. This effect is similar to the design of anti-roll fins or damping chambers on ships, helping to suppress roll and heave movements.

[0048] The buoyancy adjustment device controls the raising and lowering of multiple columns 1 to ensure that the water surface line is within the contact section 11.

[0049] The telescopic mechanism 113 described in this application is driven by a hydraulic device and has a nitrogen-filled chamber on its outer side. The nitrogen-filled chamber has a pressure slightly higher than the external water pressure, and a watertight gasket is provided at the connection between the telescopic mechanism 113 and the central column 111 to form a physical barrier to prevent seawater intrusion and corrosion of critical components.

[0050] The column 1 of this invention is provided with a contact section 11 that meets the water surface. The cross-sectional area of ​​the contact section 11 can be changed compared to the cross-sectional area at both ends of the contact section 11. The contact section 11 is divided into inner and outer parts. The inner layer is a central column 111 made of high-strength and corrosion-resistant steel, and the outer layer consists of 12 independent square boxes 112. The central column 111 and the square boxes 112 are connected by a telescopic mechanism 113 driven by a hydraulic device. When the marine environment changes, the telescopic mechanism 113 is adjusted to push the square boxes 112 outward or retract them inward, thereby adjusting the cross-sectional area of ​​the contact section in real time.

[0051] The telescopic mechanism 113 described in this application is a folding arm, one end of which is hinged to the central column 111, and the other end is hinged to the square box 112. The folding arm is connected by multiple hinges or flexible materials, realizing the switching between compact storage and free extension, which can effectively utilize limited space. Other telescopic structures such as guide rail sliding can also be used in this invention.

[0052] In this application, the bottom surface of the column 1 above the central column 111 is provided with multiple limiting grooves 114 radially, and the top of the square box 112 is provided with a round pin 115. The limiting grooves 114 and the round pin 115 cooperate to ensure that the square box 112 moves strictly radially when moving horizontally. This invention provides limiting grooves 114 at the bottom of the upper column 1, which tightly cooperate with the round pin 115 at the top of the square box 112, ensuring that the square box 112 moves strictly radially under the push of the telescopic mechanism 113, preventing circumferential movement due to wave loads.

[0053] The buoyancy adjustment device described in this application is a float 2, which is a hollow column structure with a dynamic ballast tank inside. There are four columns 1 arranged at the four corners of a square, and their bottoms are fixed by two alternately arranged horizontal supports 12 and two floats 2. The two horizontal supports 12 and two floats 2 are staggered along the four sides of the square, as shown in the attached figure. Figure 11 As shown. This invention adjusts the ballast tank inside the bottom buoy 2 to change the position of the center of gravity of the offshore platform, thereby adjusting the position of the waterline to near the variable cross-section contact section, thus better reflecting the function of the variable cross-section.

[0054] The equivalent radius of the horizontal movement of the telescopic mechanism 113 adjusting the square box 112 described in this application is 70%-120% of the column radius, as shown in the attached figure. Figure 3 When the telescopic mechanism 113 is fully retracted, the overall cross-sectional profile of the multiple square boxes 112 is annular. Each square box is a 1 / 12th of an annulus.

[0055] In this application, 12 square boxes 112 are evenly arranged on the outer periphery of each column 1.

[0056] The central column 111 described in this application is made of corrosion-resistant reinforced structural steel, and the square box 112 is molded from hollow glass microspheres and resin. Corrosion-resistant reinforced structural steel is a type of steel achieved through alloying design, advanced process control, and surface modification technology, possessing both high strength and excellent corrosion resistance. The square box 112 is molded from a new composite material of hollow glass microspheres and resin. This material is lightweight, corrosion-resistant, and high-strength, which can significantly improve the service life of the square box 112.

[0057] Studies have found that the wave loads from the waterline are the primary factor affecting the stability of offshore platform foundations. Since impact waves at the waterline are unstable, this invention incorporates a contact section 11 on the column 1 that intersects with the waterline. This contact section 11 is designed with an adjustable cross-sectional size, causing the platform's natural period to be offset from the wave period, thus avoiding resonance. This significantly reduces the wave loads and dynamic responses on the circumferential columns while ensuring the stability of the platform foundation. This effectively improves the seakeeping and economic efficiency of the offshore platform, expands its application under broader wind and wave conditions, and results in a relatively simple foundation structure with substantial economic benefits.

[0058] A resonance suppression control system for the above-mentioned variable cross-section column-type offshore platform foundation includes a wave detection module 101, a spectrum analysis module 102, a telescopic mechanism control module 103, and an active vibration damping control module 104.

[0059] The wave detection module 101 is used to collect wave height time series data around the platform foundation in real time and transmit it to the spectrum analysis module 102.

[0060] The spectrum analysis module 102 is used to calculate the current wave energy density spectrum and extract the main frequency based on the wave height time series data. The main frequency is defined as the frequency f0 corresponding to the peak value of the energy spectrum. The spectrum analysis module 102 transmits f0 to the active vibration control module 104 in real time.

[0061] The telescopic mechanism control module 103 transmits the cross-sectional area S of the platform's waterline contact section to the active vibration damping control module 104 in real time, and drives the telescopic mechanism to extend or retract according to the control commands of the active vibration damping control module 104, so that the cross-sectional area S of the platform's waterline contact section is within a preset range [S]. min S max Continuously adjustable within;

[0062] The active vibration damping control module 104 incorporates a digital twin model of the dynamic response of the offshore hydrogen production platform. Based on the real-time input f0 and the cross-sectional area S of the contact section between the platform and the waterline, it dynamically calculates the platform's natural period T. s It generates control commands and sends them to the telescopic mechanism control module 103, causing T... ssatisfy:

[0063] |1 / T s -f0|≥Δ

[0064] Where Δ is the frequency isolation margin set according to the platform structure safety factor.

[0065] The wave detection module 101 described in this application includes at least two sets of wave height meters circumferentially deployed along the foundation of the offshore platform. The detection area of ​​the wave height meters is a radius of 200-500 meters around the foundation of the platform. The spectrum analysis module 102 is connected to the embedded processor of the wave height meters and performs segmented windowing processing and calculation on the wave height data based on the improved Welch algorithm.

[0066] This invention combines wave prediction algorithms with real-time sensor data, and through intelligent terminal control, adjusts the cross-sectional area S of the platform's waterline contact section in real time to improve response efficiency. This invention can be applied to various offshore operating platforms, such as offshore hydrogen production platforms. Offshore hydrogen production platforms utilize water molecules in seawater, decomposing them into hydrogen and oxygen through electrolysis or other technologies. Offshore hydrogen production can utilize renewable energy sources such as wind and solar power to electrolyze seawater and produce hydrogen, helping to reduce dependence on fossil fuels and promoting the development of clean energy. Although hydrogen is widely favored as a clean energy source, its unstable molecular structure makes it highly susceptible to explosion. This invention provides a reliable technical solution for the offshore hydrogen production industry, possessing high seaworthiness, practicality, economy, significant market potential, and environmental value.

[0067] The working principle of this invention is as follows:

[0068] Referring to the restoring force coefficient formulas listed below in the heave and roll directions, it can be seen that when an offshore platform is being hoisted, it is easily affected by wind and waves due to its small draft and is prone to swaying. Increasing the waterline area will increase the platform's initial stability and its restoring force coefficients in the heave and roll degrees of freedom will also be greater, thus making it easier for the platform to return to its original stationary state.

[0069] czz=ρgAWL

[0070]

[0071] In the formula, c zz and c ΦΦ Let A and B be the restoring force coefficients in the heave and roll directions, respectively, where ρ is the density of water, g is the acceleration due to gravity, and A is the acceleration due to gravity. WL The area of ​​the waterline. For drainage volume, Initial metastability (a core parameter for measuring ship stability, referring to the vertical distance between the ship's center of gravity and its metacenter. It directly affects the ship's ability to regain balance after being subjected to external forces; under otherwise unchanged conditions, the waterline area A) is... WL High initial stability (They are positively correlated).

[0072] Therefore, when the offshore platform is being hoisted, the telescopic mechanism 113 will move the rectangular box 112 from... Figure 2 and Figure 3 The fully contracted state shown is adjusted to Figure 6 and Figure 7 The fully extended position shown maximizes the waterline area, which is most conducive to returning the offshore platform to its original stationary state and completing the hoisting of the offshore platform.

[0073] Reducing the cross-sectional area S of the platform's waterline contact section can weaken the interaction between the platform and the waves, thus relatively reducing the platform's displacement and angular response in the waves. Under the same conditions, the platform's RAO (the ratio of its amplitude to the wave amplitude when it moves with the wave) will also decrease. However, reducing the cross-sectional area S of the platform's waterline contact section may affect the resonant period of the floating body. For example, when the waterline area is reduced, the platform's natural heave and pitch periods will increase.

[0074] Figure 13 The figure shows the energy distribution of waves at different frequencies in a certain sea area. The wave energy is the largest when the frequency is about 0.75 rad / s. If a platform is located in this sea area, the platform's natural period should avoid this frequency to prevent resonance, which would have an adverse effect on the platform's stability.

[0075]

[0076] In the formula, T heave and T pitch Let be the natural periods of the platform's heave and pitch, respectively; M be the mass of the platform; and ΔM be the additional mass of the platform.

[0077] Therefore, when the platform is operating in the waves, the resonance suppression control system analyzes the real-time sea conditions and calculates the frequency f0 corresponding to the peak value of the wave energy density spectrum in the sea area. Under the premise of avoiding resonance caused by the same f0 as the platform's natural period, the cross-sectional area S of the platform's waterline contact section is reduced so that the offshore platform can achieve the best wave resistance effect.

[0078] The embodiments of the present invention disclosed above are merely illustrative of the invention. These embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention.

Claims

1. A resonance suppression control system for a variable cross-section column-type offshore platform foundation, characterized in that: It includes a wave detection module (101), a spectrum analysis module (102), a telescopic mechanism control module (103), and an active vibration damping control module (104); The variable cross-section column-type offshore platform foundation includes multiple columns (1) and a buoyancy adjustment device; Each column (1) is provided with a contact section (11) that intersects with the water surface line. The contact section (11) is divided into two parts: the inner part is a central column (111) with a radius smaller than that of the column (1), and the outer part is a plurality of square boxes (112) evenly arranged in the circumference. The square boxes (112) are connected to the central column (111) through a telescopic mechanism (113). The square boxes (112) can move in the horizontal direction. The buoyancy adjustment device controls the raising and lowering of multiple columns (1) to ensure that the water surface line is within the contact section (11); The telescopic mechanism (113) is driven by a hydraulic device and has a nitrogen-filled chamber on its outer side; The telescopic mechanism (113) is a folding arm, one end of which is hinged to the central column (111) and the other end is hinged to the square box (112); The bottom surface of the column (1) above the central column (111) is provided with multiple limiting grooves (114) in the radial direction, and the top of the square box (112) is provided with a round pin (115). The limiting grooves (114) and the round pin (115) cooperate to ensure that the square box (112) moves strictly in the radial direction when it moves horizontally. The telescopic mechanism (113) adjusts the equivalent radius range of the horizontal movement of the square box (112) to be 70%-120% of the radius of the column (1). When the telescopic mechanism (113) is fully retracted, the overall cross-sectional profile of the multiple square boxes (112) is annular. The wave detection module (101) is used to collect wave height time series data around the platform foundation in real time and transmit it to the spectrum analysis module (102); The spectrum analysis module (102) is used to calculate the current wave energy density spectrum and extract the main frequency based on the wave height time series data. The main frequency is defined as the frequency f0 corresponding to the peak value of the energy spectrum. The spectrum analysis module (102) transmits f0 to the active vibration control module (104) in real time. The telescopic mechanism control module (103) transmits the cross-sectional area S of the platform's waterline contact section to the active vibration damping control module (104) in real time, and drives the telescopic mechanism (113) to extend or retract according to the control commands of the active vibration damping control module (104), so that the cross-sectional area S of the platform's waterline contact section is within a preset range [S]. min S max Continuously adjustable within; The active vibration damping control module (104) incorporates a digital twin model of the dynamic response of the offshore hydrogen production platform. Based on the real-time input of f0 and the cross-sectional area S of the platform's waterline contact section, it dynamically calculates the platform's natural period T. s And generate control commands and send them to the telescopic mechanism control module (103) to make T s satisfy: |1 / T s -f0|≥Δ Where Δ is the frequency isolation margin set according to the platform structure safety factor.

2. The resonance suppression control system for a variable cross-section column-type offshore platform foundation according to claim 1, characterized in that: The buoyancy adjustment device is a float (2), which is a hollow column structure with a dynamic ballast tank inside. There are four columns (1) arranged in a square at the four corners, and the bottom is fixed by two alternately arranged cross braces (12) and two floats (2).

3. The resonance suppression control system for a variable cross-section column-type offshore platform foundation according to claim 1, characterized in that: Each column (1) has 12 square boxes (112) evenly arranged around its outer perimeter.

4. The resonance suppression control system for a variable cross-section column-type offshore platform foundation according to claim 1, characterized in that: The central column (111) is made of corrosion-resistant reinforced structural steel, and the square box (112) is made of hollow glass microspheres and resin composite molding.

5. The resonance suppression control system for a variable cross-section column-type offshore platform foundation according to claim 1, characterized in that: The wave detection module (101) includes at least two sets of wave height meters deployed circumferentially along the platform foundation on the coast. The detection area of ​​the wave height meters is a radius of 200-500 meters around the platform foundation. The spectrum analysis module (102) is connected to the embedded processor of the wave height meters and performs segmented windowing processing and calculation on the wave height data based on the improved Welch algorithm.

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