Sea wave disturbance resisting method and system for offshore wind turbine generator

Abstract

The invention provides a sea wave disturbance resisting method and system for an offshore wind turbine generator, and the method comprises the steps: 1, obtaining sea surface distance data in real time through a sensor disposed on a tower drum, and judging whether sea waves are in a wave crest approaching state or not according to the change of the distance data; 2, when it is judged that the wave crest is close to the state, the energy level of sea wave impact is measured; and 3, according to the judged energy level, the opening and closing states of a valve of the variable-rigidity hydraulic supporting system are controlled, so that the connecting rigidity of the bottom of the tower drum is adjusted or locking operation is executed. According to the invention, data can be obtained through the physical sensor before sea wave impact, and the rigidity and energy absorption strategy of the connecting piece at the bottom of the tower drum can be directly changed through judgment of a series of logic gates, so that the tower drum is switched between hard contact and force unloading, and the resonance condition of sea waves is destroyed.

Description

Technical Field

[0001] This invention relates to the field of wave disturbance resistance for offshore wind turbines, and particularly to a method and system for wave disturbance resistance for offshore wind turbines. Background Technology

[0002] Current surge protection technologies for offshore / offshore wind turbines mainly focus on two areas. The first is the use of passive damper structures, such as tuned mass dampers (TMDs) installed at the top of the tower. These rely primarily on physical resonance to counteract swaying, but cannot cope with varying wave frequencies. The second approach utilizes aerodynamic damping control structures, generating aerodynamic thrust by adjusting the blade pitch angle to counteract tower swaying. This method typically requires complex mathematical models (such as Kalman filtering and model predictive control, MPC), and the response often lags behind wave impact (i.e., adjustments are made only after swaying has occurred). Summary of the Invention

[0003] This invention provides a method and system for resisting wave disturbance in offshore wind turbines, which addresses the shortcomings of existing technologies. Before wave impact, data is acquired through physical sensors, and a series of logic gates are used to determine the stiffness and energy absorption strategy of the bottom connector of the tower, causing the tower to switch between hard contact and unloading, thereby disrupting the resonance conditions of the waves.

[0004] This invention provides a method for resisting wave disturbance in offshore wind turbines, comprising: Step 1: Real-time sea surface distance data is acquired using sensors mounted on the tower, and changes in the distance data are used to determine whether the waves are approaching their crests. Step 2: When it is determined that the wave crest is approaching, measure the energy level of the wave impact; Step 3: Based on the determined energy level, control the opening and closing status of the valves in the variable stiffness hydraulic support system to adjust the connection stiffness at the bottom of the tower or perform a locking operation.

[0005] According to the method for resisting wave disturbance of offshore wind turbines provided by the present invention, step 1, the step of determining whether the waves are in a state of approaching wave crest, specifically includes: The system reads the vertical distance Dreal from the sensor to the water surface below in real time, and compares the vertical distance Dreal with the preset reference calm sea surface distance Dref, and calculates the difference ΔD=Dref - Dreal; If ΔD>0, it is determined to be a state of near-peak. If ΔD≤0, it is determined to be a trough or calm state, and the system maintains the current state without taking any action.

[0006] According to the method for resisting wave disturbance of an offshore wind turbine provided by the present invention, in step 2, the energy level of the wave impact is determined by the following method: Record the maximum difference value ΔDmax in the state when the wave crest approaches, and compare the maximum difference value ΔDmax with a preset first-level warning threshold Hlow and a second-level danger threshold Hhigh; If ΔDmax < Hlow, it is determined as low-energy waves; If Hlow ≤ ΔDmax < Hhigh, it is determined as medium-energy waves; If ΔDmax ≥ Hhigh, it is determined as high-energy waves.

[0007] According to the method for resisting wave disturbance of an offshore wind turbine provided by the present invention, when it is determined as low-energy waves, step 3 specifically includes: Control the locking valve of the variable stiffness hydraulic support system to remain fully open, enable the hydraulic cylinder to freely expand and contract, absorb energy by the damping generated by the flow of hydraulic oil, and maintain the stiffness of the tower barrel.

[0008] According to the method for resisting wave disturbance of an offshore wind turbine provided by the present invention, when it is determined as medium-energy waves, step 3 specifically includes: Calculate the impact frequency Fwave of the current wave; Obtain the natural frequency range [Ftower_min, Ftower_max] of the wind turbine tower barrel; Judge whether Fwave falls within the natural frequency range; If Fwave falls within the natural frequency range, trigger the high stiffness mode; If Fwave does not fall within the natural frequency range, trigger the flexible energy absorption mode.

[0009] According to the method for resisting wave disturbance of an offshore wind turbine provided by the present invention, the specific control method of the high stiffness mode includes: The system controls the variable stiffness hydraulic support system to close the large-flow solenoid valve, only retain the small-flow damping holes, and open the oil inlet passage of the high-pressure accumulator to increase the connection stiffness at the bottom of the tower barrel, so that the overall natural frequency of the tower barrel rises and is greater than the wave impact frequency Fwave.

[0010] According to the method for resisting wave disturbance of an offshore wind turbine provided by the present invention, the specific control method of the flexible energy absorption mode includes: The system controls the variable stiffness hydraulic support system to open the large-flow solenoid valve, allowing the hydraulic cylinder to perform a large-amplitude piston movement to absorb the wave impact energy through the throttling effect of the hydraulic oil flowing through the valve port.

[0011] According to the method for resisting wave disturbance of offshore wind turbines provided by the present invention, when the wave is determined to be a high-energy wave, step 3 includes a hydraulic deadlock step, which specifically includes: All inlet and outlet valves of the variable stiffness hydraulic support system are completely closed, turning the hydraulic cylinder into a rigid body and making the tower completely fixed to the foundation.

[0012] According to the offshore wind turbine anti-wave disturbance method provided by the present invention, when the wave is determined to be a high-energy wave, step 3 further includes a nacelle coordination step, which specifically includes: Identify the location of the sensor that detected ΔDmax to determine the direction of the waves and read the current yaw angle of the cabin; Calculate the angle α between the direction of the incoming waves and the orientation of the cabin; If α < 30 degrees, then control the wind turbine blades to pitch to 90 degrees in a feathering state; If α ≥ 30 degrees, the yaw motor will be controlled to rotate the windward side of the nacelle to face away from the waves.

[0013] The present invention also provides an anti-wave disturbance system for offshore wind turbines, comprising: The status determination module acquires real-time sea surface distance data through sensors deployed on the tower, and determines whether the waves are approaching their crests based on changes in the distance data. The rating determination module measures the energy level of wave impact when it is determined that the wave crest is approaching. The execution control module controls the opening and closing status of the valves in the variable stiffness hydraulic support system based on the determined energy level, so as to adjust the connection stiffness at the bottom of the tower or perform a locking operation.

[0014] The method and system for resisting wave disturbances in offshore wind turbines provided by this invention eliminates the need for complex fluid dynamics models or AI predictions. It relies entirely on sensor threshold triggering and logic gate judgment, resulting in higher system robustness and preventing runaway due to algorithm non-convergence. Furthermore, unlike traditional passive damping, this invention actively alters the stiffness characteristics of the physical structure upon detecting resonance risk, eliminating the conditions for resonance at its source. Moreover, by determining the wave energy level (low, medium, high), three different physical strategies—free damping, variable stiffness frequency shifting, and rigid locking—are adopted respectively, protecting the turbine's safety while avoiding mechanical wear caused by frequent small wave movements. Finally, by using direct laser / radar ranging as a feedforward signal, the switching of solenoid valves can be completed before the waves contact the tower structure, solving the problem of lag in traditional control systems. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0016] Figure 1 This is a flowchart illustrating the method for resisting wave disturbance in offshore wind turbines provided by the present invention.

[0017] Figure 2 This is a schematic diagram of the structure of the offshore wind turbine anti-wave disturbance system provided by the present invention.

[0018] Figure 3 This is a schematic diagram of the structure of the electronic device provided by the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0020] The following is combined Figures 1 to 3 This invention describes embodiments of the method and system for resisting wave disturbance in offshore wind turbines. It should be understood that the following descriptions are merely illustrative embodiments of the invention and do not constitute any specific limitation on the invention.

[0021] like Figure 1 As shown, the present invention provides a method for resisting wave disturbance in offshore wind turbines, comprising: Step 1: Real-time sea surface distance data is acquired using sensors mounted on the tower, and changes in the distance data are used to determine whether the waves are approaching their crests. Step 2: When it is determined that the wave crest is approaching, measure the energy level of the wave impact; Step 3: Based on the determined energy level, control the opening and closing status of the valves in the variable stiffness hydraulic support system to adjust the connection stiffness at the bottom of the tower or perform a locking operation.

[0022] The wave disturbance mitigation method for offshore wind turbines provided in this invention eliminates the need for complex hydrodynamic models or AI predictions. It relies entirely on sensor threshold triggering and logic gate judgment, resulting in higher system robustness and preventing runaway due to algorithm non-convergence. Furthermore, unlike traditional passive damping, this invention proactively alters the stiffness characteristics of the physical structure upon detecting resonance risk, eliminating the conditions for resonance at its source. Moreover, by determining the wave energy level (low, medium, high), three different physical strategies—free damping, variable stiffness frequency shifting, and rigid locking—are employed respectively, protecting the turbine's safety while preventing mechanical wear caused by frequent small wave movements. Finally, by using direct laser / radar ranging as a feedforward signal, the switching of solenoid valves can be completed before the waves contact the tower structure, solving the problem of lag in traditional control methods.

[0023] The above method will be described in detail below with reference to embodiments. It should be understood that the following description is merely an illustrative embodiment of the present invention and does not constitute any limitation on the present invention.

[0024] First, the method of this invention begins with step 1, which involves acquiring real-time sea surface distance data using sensors deployed on the tower and determining whether the waves are approaching their crests based on changes in the distance data. Specifically, step 1 is the sensing and initiation point of the entire anti-disturbance control method, and its core lies in realizing the transformation from passive response to active feedforward. On the outer wall of the wind turbine tower, at a distance of 5-10 meters from the designed average sea level (this height needs to be higher than the highest point of conventional waves to prevent the sensors from being submerged, but not too high to avoid exceeding the detection range), several (e.g., 4 or 8) laser rangefinders or radar level gauges are evenly arranged along the circumference. The system first sets a reference calm sea surface distance threshold Dref, which is usually calibrated as the vertical distance from the sensor installation height to the still sea surface. Non-contact laser or radar sensors are used to avoid corrosion and physical impact damage caused by direct contact with seawater; and the circumferential distribution is to enable all-round capture of waves from different directions, avoiding blind spots. In this way, a 360-degree real-time monitoring network centered on the tower was established, which can obtain the physical shape data of the waves in advance before the waves come into contact with the tower's physical structure, thus gaining a valuable physical time window for subsequent rapid response.

[0025] Next, the control system reads the vertical distance Dreal detected by each sensor to the water surface below at a millisecond-level sampling frequency in real time. Then, the system performs a subtraction operation to calculate the difference ΔD = Dref - Dreal. When the sea surface is calm, Dreal is approximately equal to Dref, and the difference is close to 0. When an object (wave) rises and approaches the sensor, the distance Dreal measured by the sensor decreases, causing the difference ΔD to become positive. The magnitude of ΔD directly reflects the degree of rise of the current wave relative to the still sea level (i.e., wave height). In this way, complex physical quantities of the marine environment can be transformed into a single, linear numerical signal ΔD. This data processing process requires no complex modeling calculations, has a low computational load, and ensures that the controller can process signals at a high speed, meeting the stringent real-time requirements for resisting wave disturbances.

[0026] Then, the specific judgment process is carried out. Specifically, the system monitors the value of ΔD in real time. If the calculation result shows that ΔD>0, the system immediately determines that the current position is in a state of approaching wave crest. ΔD>0 means that the water surface is already higher than the reference level and is pressing against the tower. This physically corresponds to the crest stage of an ocean wave. At this time, although the huge impact force may not have fully acted on the bottom of the tower, the potential energy of the wave is being converted into kinetic energy and approaching. Unlike the delayed logic of adjusting after swaying in existing technologies, this step identifies the risk before the wave has just begun to rise and before it causes violent swaying of the tower. This gives the system enough time (usually several hundred milliseconds to several seconds) to complete the switching of hydraulic valves before the main force of the wave arrives. Correspondingly, if the calculation result shows that ΔD≤0, the system determines that the current state is in a wave trough or calm state. At this time, the system determines that there is no direct impact risk, maintains the current control state, and does not trigger subsequent energy level judgment or stiffness adjustment actions. When ΔD < 0, it means the water level is below the reference level, indicating a wave trough; when ΔD = 0, it means the sea is calm. Under these conditions, the hydrodynamic load on the tower is minimal, requiring no adjustment to stiffness. Therefore, this logic gate serves as both signal filtering and system protection. It prevents the system from frequently operating under invalid signals (such as minor water surface fluctuations or invalid data during wave troughs), prevents hydraulic valves from overheating or having their lifespan reduced due to frequent and meaningless opening and closing, and ensures the system only consumes energy for regulation when a real threat (wave crest) occurs.

[0027] Next, the method of this invention proceeds to step 2, which involves measuring the energy level of the wave impact when a wave crest is detected as approaching. Step 2 mainly involves the classification and preprocessing logic of the wave impact energy. This step is the decision-making link connecting the sensing process and the execution process. By comparing threshold values ​​of physical quantities, the system can distinguish between sea conditions of different levels of danger, thereby avoiding frequent malfunctions of the system under small waves or insufficient response under extreme waves.

[0028] Specifically, when step 1 determines that ΔD > 0 (i.e., the wave crest is approaching), the system does not act immediately. Instead, it initiates a short-cycle timing window (e.g., corresponding to 1 / 4 of the wave cycle) to continuously monitor the sensor values ​​and record the maximum difference ΔDmax during this process. This is because the destructive power of a wave depends primarily on its wave height (potential energy) and wave speed (kinetic energy). Since the sensor detects changes in liquid level, a single sample value may be at the rising edge of the wave rather than at the crest, failing to accurately reflect the wave's impact energy. By locking the maximum value ΔDmax, the system ensures that its decisions are based on the current wave's maximum potential destructive power. Therefore, this improves the accuracy of the system's judgment, prevents misjudgments of wave level due to improper sampling timing (e.g., misjudging a large rising wave as a small wave), and ensures the safety of subsequent stiffness adjustment strategies.

[0029] Furthermore, this invention presets two physical thresholds: a primary warning threshold (Hlow) and a secondary danger threshold (Hhigh). These two thresholds divide the sea state into three intervals, each corresponding to a different physical control strategy. It should be understood that the primary warning threshold (Hlow) and the secondary danger threshold (Hhigh) can be set according to the actual environment of the wind turbine. For example, for monopile foundation wind turbines with shallow water depths (e.g., 15-30 meters) and close to shore, the primary warning threshold (Hlow) can be set to 1.5 meters, and the secondary danger threshold (Hhigh) can be set to 4.0 meters. For large-megawatt (10MW and above) wind turbines with deeper water depths (e.g., over 50 meters) and more severe sea conditions, the primary warning threshold (Hlow) can be set to 2.5 meters, and the secondary danger threshold (Hhigh) can be set to 6.0 meters. Additionally, for implementations that are not limited to a specific turbine model but are dynamically defined based on the ultimate load of the tower design, the primary warning threshold (Hlow) can be set to 15% of the tower design platform height, and the secondary danger threshold (Hhigh) can be set to 40% of the tower design platform height.

[0030] Specifically, for the determination of low-energy ocean waves (ΔDmax < Hlow), when the detected maximum wave height difference is less than the first-level warning threshold, the system determines it as low-energy ocean waves. At this time, the system does not trigger the variable stiffness action, but maintains the locking valve of the hydraulic support system in the fully open state. In the ocean environment, there are tiny fluctuations (background noise) on the sea surface for the vast majority of the time. The energy of these small waves is not sufficient to cause harmful vibrations or resonances of the tower barrel. If the system switches the opening and closing of the high-pressure valve for every tiny fluctuation, it will cause severe wear of hydraulic components (such as solenoid valves, seals) and consume a large amount of electric energy. In this way, it can extend the equipment life, filter out invalid interference, and significantly reduce the action frequency of the actuator. Moreover, at this time, the hydraulic cylinder is in the free telescopic state, and the hydraulic oil reciprocates in the pipeline to generate fluid damping, which is equivalent to a passive shock absorber and can flexibly absorb the impact energy of tiny waves and reduce the fatigue stress of the tower base.

[0031] Secondly, for the determination of medium-energy ocean waves (Hlow ≤ ΔDmax < Hhigh), when the maximum wave height difference is between the two, the system determines it as medium-energy ocean waves. At this time, the system points the logic to the stiffness misalignment frequency control process. Such ocean waves have a certain amount of energy and often show regular periods. At this time, the greatest risk faced by the wind turbine is not being toppled, but resonance. If the impact frequency of the ocean waves is close to the natural frequency of the tower barrel, even if the waves are not huge, it will cause large-amplitude swaying of the tower barrel. Therefore, the core of this stage is not to resist, but to avoid the resonance frequency by changing the stiffness. In this way, the system identifies that this is a working condition that needs to be avoided, thereby activating the subsequent frequency matching logic and changing the physical characteristics of the tower barrel by adjusting the hydraulic stiffness to eliminate the physical conditions for resonance to occur at the source.

[0032] Furthermore, for the determination of high-energy ocean waves (ΔDmax ≥ Hhigh), when the maximum wave height difference exceeds the second-level danger threshold, the system determines it as high-energy / extreme ocean waves (such as typhoon waves, rogue waves). At this time, the system skips the frequency judgment and directly points the logic to the rigid locking and risk avoidance process. Facing huge waves, the primary risk faced by the tower barrel is structural damage (such as buckling, overturning). At this time, it is meaningless to discuss the frequency. It is necessary to ensure the firmest connection between the tower barrel and the foundation, that is, to pursue the maximum anti-overturning moment. Any flexible connection or damping movement may cause the tower body to incline too much and become unstable. By determining this level, the system can trigger hydraulic deadlock in milliseconds, instantly turning the entire device into a rigid connection body to resist the impact with the strongest physical posture. Moreover, this determination logic has the highest priority, ensuring that in extremely dangerous working conditions, it no longer wastes time calculating the frequency but directly executes the insurance operation.

[0033] Furthermore, according to different energy levels, the present invention performs different operations in step 3. That is, the system changes the internal oil circuit state of the variable stiffness hydraulic support system by physical means according to different energy levels, so as to achieve the dynamic change of the connection stiffness at the bottom of the tower barrel.

[0034] Specifically, when step 2 determines that the sea wave is a low-energy sea wave (ΔDmax < Hlow), the control system sends an instruction to the hydraulic support system to maintain the locking valves of all hydraulic cylinders in a fully open state and not to close the large-flow solenoid valve. In this case, low-energy sea waves usually appear as breaking waves with a small wave height and a high frequency. Such sea waves pose a minimal threat to the structural safety of the tower barrel. However, if the connection at the bottom of the tower barrel is too rigid, every tiny impact of the high-frequency breaking waves will be transmitted to the tower barrel and the nacelle in the form of vibration, and long-term accumulation will cause unnecessary mechanical fatigue. At this time, keeping the hydraulic system fully open allows the piston of the hydraulic cylinder to float slightly with the sea wave, and the fluid viscous damping generated by the free flow of the hydraulic oil in the pipeline is used to dissipate energy. In this way, the filtering effect on high-frequency micro-disturbances can be achieved, avoiding frequent stiffness switching, reducing the action wear of the valve group, and at the same time reducing the fatigue accumulation of each component of the unit.

[0035] When step 2 determines that the sea wave is a medium-energy sea wave (Hlow ≤ ΔDmax < Hhigh), the system enters the most critical stage of dynamic stiffness adjustment. In this stage, the system first calculates the sea wave impact frequency Fwave and compares it with the natural frequency range [Ftower_min, Ftower_max] of the tower barrel.

[0036] For the first case, there is a resonance risk (triggering the high stiffness mode). Fwave falls within the natural frequency range of the tower barrel, which means that if not intervened, the periodic impact of the sea wave will resonate with the tower barrel, resulting in an exponential amplification of the amplitude. At this time, the system immediately closes the large-flow solenoid valve connecting the hydraulic cylinder, cutting off the main return oil circuit; at the same time, it opens the oil inlet circuit leading to the high-pressure accumulator and only retains a damping hole with a very small aperture for pressure maintenance. In this case, according to the principle of mechanical vibration, the natural frequency w of the structure is proportional to the square root of the stiffness K. When the large-flow valve is closed and the high-pressure accumulator is connected, the oil in the hydraulic cylinder is enclosed in a narrow space and is subjected to high-pressure pre-tightening. The hydraulic support system instantaneously changes from a flexible state to a state that is extremely difficult to compress. This physically manifests as a sharp increase in the connection stiffness K at the bottom of the tower barrel. As the stiffness K increases, the overall natural frequency of the tower barrel is forced to increase, so that its value jumps out of the range of the sea wave frequency Fwave. In this way, by physically changing the structural stiffness, the necessary condition for resonance (frequency consistency) is destroyed, so that before the sea wave energy is completely transmitted to the tower barrel, the accumulation of the resonance amplitude is suppressed, protecting the unit from violent shaking.

[0037] In the second scenario, there is no risk of resonance (triggering the flexible energy absorption mode). The F-wave does not fall within the tower's natural frequency range, indicating that although the wave frequency has moderate energy, it will not cause resonance. In this case, the system controls the opening of the high-flow solenoid valve, allowing the piston of the hydraulic cylinder to perform a relatively large reciprocating motion within a certain stroke. In the non-resonance state, simple hard contact would cause the instantaneous peak value of the wave impact force to be too large, easily causing cracks in the tower base welds. With the high-flow valve open, the hydraulic cylinder acts as a shock absorber. When the wave impacts the tower, it pushes the piston, forcing the hydraulic oil to flow through the valve port at high speed. According to fluid mechanics principles, the fluid passing through the throttling orifice will generate a huge pressure loss, converting the kinetic energy of the wave into heat energy for dissipation. In this way, through flexible force relief, the peak impact load transmitted to the wind turbine foundation is reduced, extending the foundation's service life and acting as a buffer protection similar to a car shock absorber.

[0038] Furthermore, when step 2 determines that it is a high-energy wave (ΔDmax≥Hhigh), it indicates that an extremely severe sea condition (such as typhoon waves) has been encountered. Simple damping or stiffness adjustment is no longer sufficient to ensure safety, and the system enters the highest priority survival mode.

[0039] Specifically, the system forcibly closes all inlet and outlet valves of the variable stiffness hydraulic support system (including high-flow valves, low-flow orifices, and accumulator passages), implementing a physical lock-up. At this point, the oil inside the hydraulic cylinder is completely sealed off. Due to the incompressibility of the fluid, the hydraulic cylinder essentially becomes a rigid connecting rod. This reconnects the tower to the foundation, eliminating any elastic displacement in the hydraulic system, ensuring the structure has maximum resistance to overturning moment, preventing mechanical impact due to piston stroke exhaustion, and using the most traditional rigid structure to withstand extreme external forces.

[0040] In addition, the system uses sensors to locate the direction of the incoming waves and calculate the angle α. If α < 30 degrees (heading wave), the blades are controlled to pitch to 90 degrees (feathering); if α ≥ 30 degrees (side wave), the yaw motor is controlled to rotate the nacelle so that the windward side faces away from the waves. Adjusting the blade angle of attack to 90 degrees, aligning the leading edge of the blades with the wind direction, reduces aerodynamic lift to zero, greatly reducing the overturning moment generated by wind load and preventing the destructive effect of the superposition of wind and wave loads. Furthermore, offshore wind turbine nacelles are usually streamlined. When large side waves strike, the side of the nacelle has a large stress area; rotating it to face away from the waves, utilizing the streamlined tail to absorb the waves, can significantly reduce the fluid resistance of the wave impact on the nacelle structure. In this way, through aerodynamic and hydrodynamic attitude adjustments, the external energy input received by the unit is reduced from the source, and in conjunction with the hydraulic lock at the bottom, a three-dimensional protection system of top unloading and bottom protection is formed.

[0041] In the above process, the included angle α is determined by the yaw angle. Specifically, the yaw angle (θyaw) refers to the absolute azimuth of the wind turbine nacelle (e.g., with due north as 0 degrees and the nacelle facing due east, the yaw angle is 90 degrees). This is a real-time status value read by the turbine's own encoder. The wave direction (θwave) refers to the absolute azimuth of the source of the wave impact detected by the sensor (e.g., if a large wave is detected due north, the wave direction is 0 degrees). This is the external environment value identified through the above steps. The included angle (α) is the relative angle difference between the two, i.e., α = |θwave - θyaw|.

[0042] Furthermore, in embodiments of the present invention, the method for resisting wave disturbances in offshore wind turbines may further include a reset step. Specifically, the reset step may include starting a reset timer after performing a control operation. If, within a preset reset time, the difference ΔD detected by the sensor is consistently less than the first-level warning threshold Hlow, the current stiffness control or locking state is released, and the variable stiffness hydraulic support system is restored to its initial state; otherwise, the reset timer is reset.

[0043] Specifically, the core of this process lies in setting an observation window to prevent the system from frequently switching between critical states. After the system performs the stiffness adjustment or rigid locking operation described above, it does not immediately cancel the operation; instead, a reset timer (e.g., set to 30 seconds) is immediately started in the background. Ocean waves are periodic and occur in clusters; a large wave is often followed by a subsequent wave train. If the system resets immediately upon detecting a moment of calm, it may be impacted again a few seconds later. Therefore, this invention introduces a time-dimensional buffer or hysteresis. In this way, frequent opening and closing of the hydraulic valve assembly and locking mechanism in a short period is avoided, thereby extending the service life of mechanical components (especially solenoid valves and seals) and reducing mechanical fatigue.

[0044] During the Treset countdown, the system continuously collects real-time data ΔD (difference between sea surface and ground level) from all sensors and continuously checks whether ΔD remains below the first-level warning threshold Hlow. Hlow is the dividing line for determining whether intervention is needed. Only when the detection values ​​of all sensors are below this threshold does it mean that the sea state has returned to a safe / calm state where intervention by the variable stiffness system is not required. Through continuous threshold comparison, the system ensures that the defense is only lifted when the sea state is truly stable, avoiding misoperation and ensuring that the wind turbine is always in the most suitable physical protection state for the current sea state.

[0045] If at any moment within the Treset timing window, the system detects that ΔD of any one sensor is ≥ Hlow (i.e., a medium-energy or high-energy ocean wave signal appears again), the system immediately clears the timer Treset and maintains the current control state (high stiffness or locked state) unchanged, or returns to the above process according to the new ΔD value to re-determine the energy level. That is to say, once a violation signal appears during the observation period, it indicates that the previous stable state is only temporary and the danger has not been lifted, and a new round of observation must be restarted. This can prevent premature unlocking when the storm has not completely passed, ensure that the unit maintains a stable high stiffness or locked posture under continuous wave impacts, and avoid unstable structural dynamic responses caused by frequent stiffness switching.

[0046] If the timer Treset successfully expires (i.e., the sea surface remains ΔD < Hlow throughout the 30 seconds), the system determines that the danger has been lifted. At this time, the controller sends an instruction to解除 the closed state of the hydraulic lock valve, adjusts the solenoid valve to the initial state (such as medium damping state), and (if the nacelle coordination was performed previously) controls the yaw system and pitch system to return to the normal wind-facing power generation state. That is, the system switches from the survival mode back to the production mode. Thus, on the premise of ensuring safety, through the automatic reset logic, the unit can resume normal operation in the first time, reduce the power generation loss caused by excessive shutdown, and achieve the balance between safety protection and economic benefits.

[0047] On the other hand, as Figure 2 shown, the embodiment of the present invention also provides an anti-wave disturbance system for an offshore wind turbine. The anti-wave disturbance system for an offshore wind turbine described below can be mutually referred to with the anti-wave disturbance method for an offshore wind turbine described above. The anti-wave disturbance system for an offshore wind turbine includes: A state determination module, which obtains the sea surface distance data in real time through sensors arranged on the tower barrel and determines whether the ocean wave is in a state close to the wave crest according to the change of the distance data; A level determination module, which measures the energy level of the ocean wave impact when it is determined to be in a state close to the wave crest; An execution control module, which controls the opening and closing state of the valve of the variable stiffness hydraulic support system according to the determined energy level to adjust the connection stiffness at the bottom of the tower barrel or perform a locking operation.

[0048] Figure 3 Illustrates a schematic physical structure diagram of an electronic device, as Figure 3 Note: There is an unclear expression "解除" in the translation of . It might need to be further clarified according to the specific context to provide a more accurate translation.As shown, the electronic device may include a processor 810, a communications interface 820, a memory 830, and a communication bus 840. The processor 810, communications interface 820, and memory 830 communicate with each other via the communication bus 840. The processor 810 can call logical instructions from the memory 830 to execute methods for resisting wave disturbances in offshore wind turbines.

[0049] Furthermore, the logical instructions in the aforementioned memory 830 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0050] On the other hand, the present invention also provides a computer program product, which includes a computer program that can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer is able to execute the methods for resisting wave disturbances in offshore wind turbines provided by the above methods.

[0051] In another aspect, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, is implemented to perform the wave disturbance resistance method for offshore wind turbines provided by the methods described above.

[0052] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0053] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method of offshore wind turbine unit resistance to sea wave disturbance, characterized in that, The method comprises the following steps: Step 1: Real-time acquisition of sea surface distance data by sensors arranged on the tower drum, and determination of whether the sea wave is in a wave crest approaching state according to the change of the distance data; Step 2: When it is determined that the wave crest is in the approaching state, the energy level of the sea wave impact is measured; Step 3: According to the determined energy level, the valve opening and closing state of the variable stiffness hydraulic support system is controlled to adjust the connection stiffness at the bottom of the tower drum or perform a locking operation.

2. The offshore wind turbine unit anti-sea-wave disturbance method according to claim 1, characterized in that, In step 1, the step of determining whether the sea wave is in a wave crest approaching state specifically comprises: The system reads the vertical distance Dreal of the sensor to the lower water surface in real time, compares the vertical distance Dreal with the preset reference calm sea surface distance Dref, and calculates the difference ΔD = Dref - Dreal; If ΔD > 0, it is determined that the wave crest is in the approaching state; If ΔD ≤ 0, it is determined that it is in a trough or calm state, and the system maintains the current state without action.

3. The offshore wind turbine unit anti-sea-wave disturbance method according to claim 2, characterized in that, In step 2, the energy level of the sea wave impact is determined by the following method: Record the maximum difference ΔDmax in the wave crest approaching state, and compare the maximum difference ΔDmax with the preset first warning threshold Hlow and second dangerous threshold Hhigh; If ΔDmax < Hlow, it is determined that the sea wave is low energy; If Hlow ≤ ΔDmax < Hhigh, it is determined that the sea wave is medium energy; If ΔDmax ≥ Hhigh, it is determined that the sea wave is high energy.

4. The offshore wind turbine unit anti-sea-wave disturbance method according to claim 3, characterized in that, When it is determined that the sea wave is low energy, step 3 specifically comprises: Control the locking valve of the variable stiffness hydraulic support system to keep the full open state, so that the hydraulic cylinder can freely extend and retract, and the damping generated by the flow of hydraulic oil can absorb energy and maintain the stiffness of the tower drum.

5. The offshore wind turbine unit anti-sea-wave disturbance method according to claim 3, characterized in that, When it is determined that the sea wave is medium energy, step 3 specifically comprises: Calculate the impact frequency Fwave of the current sea wave; Obtain the natural frequency interval [Ftower_min, Ftower_max] of the wind turbine tower drum; Determine whether Fwave falls within the natural frequency interval; If Fwave falls within the natural frequency interval, the high stiffness mode is triggered; If Fwave does not fall within the natural frequency interval, the flexible energy absorption mode is triggered.

6. The offshore wind turbine unit anti-sea-wave disturbance method according to claim 5, characterized in that, The specific control method of the high stiffness mode comprises: The system controls the variable stiffness hydraulic support system to close the large flow electromagnetic valve, only retains the small flow damping hole, and opens the high pressure accumulator oil inlet to increase the connection stiffness at the bottom of the tower drum, so that the overall natural frequency of the tower drum is increased and greater than the sea wave impact frequency Fwave.

7. The offshore wind turbine unit anti-sea-wave disturbance method according to claim 5, characterized in that, The specific control method of the flexible energy absorption mode comprises: The system controls the variable stiffness hydraulic support system to open the large flow electromagnetic valve to allow the hydraulic cylinder to perform large amplitude piston movement to absorb the sea wave impact energy through the throttling effect of the hydraulic oil flowing through the valve port.

8. The offshore wind turbine unit anti-sea-wave disturbance method according to claim 3, characterized in that, When it is determined that the sea wave is high energy, step 3 comprises a hydraulic dead lock step, which specifically comprises: Control all oil inlet and outlet valves of the variable stiffness hydraulic support system to be completely closed, so that the hydraulic cylinder becomes a rigid body, and the tower drum is completely fixed to the foundation.

9. The offshore wind turbine unit anti-sea-wave disturbance method according to claim 8, characterized in that, When the high-energy sea wave is determined, the step 3 further comprises a cabin coordination step, which specifically comprises: identifying the sensor orientation where ΔDmax is detected to determine the sea wave direction, and reading the current yaw angle of the cabin; calculating the included angle α between the sea wave direction and the cabin orientation; if α < 30 degrees, controlling the wind turbine blade to be pitched to a 90-degree feathering state; if α ≥ 30 degrees, controlling the yaw motor to turn the cabin windward surface to face away from the sea wave direction.

10. A system for offshore wind turbine unit resistance to sea wave disturbances, characterized by, Comprise: a state determination module that obtains real-time sea surface distance data through sensors arranged on the tower drum, and determines whether the sea wave is in a wave crest approaching state according to the change of the distance data; a grade determination module that measures the energy grade of the sea wave impact when the wave crest approaching state is determined; an execution control module that controls the valve opening and closing state of the variable stiffness hydraulic support system according to the determined energy grade, so as to adjust the connection stiffness of the tower drum bottom or execute the locking operation.

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