Nanometer generator self-powered wind power pile-based seabed scour pit piezoelectric monitoring method and system

Abstract

The invention discloses a nanogenerator-based self-powered wind power pile seabed scour pit piezoelectric monitoring method, and relates to the technical field of offshore wind power generation pile monitoring, and the method comprises the following core contents: constructing a ''seabed sensor-sea surface signal transfer module-land data processing and early warning system'' integrated architecture; the PVDF piezoelectric unit is used for realizing direct conversion from kinetic energy of ocean fluid to electric energy, synchronously converting the change of the exposed length (corresponding to the scouring depth) of the vertical plate of the sensor into a voltage signal, and transmitting the voltage signal to a land base station after processing to realize real-time monitoring; the sensor takes reinforced fiber / epoxy resin as a carrier and is coated with a plurality of corrosion-resistant coatings, and a double-layer circular array is arranged on a seabed within the range of 1 meter around a wind power pile. By means of the self-energy-supply design, the problems of high maintenance cost and poor reliability caused by the fact that traditional monitoring depends on an external power source are solved, the bottleneck of long-term stable monitoring under the complex marine environment is broken through by combining a high-sensitivity monitoring mechanism and a multi-layer protection structure, the advantages of being convenient and fast to install and controllable in cost are achieved, and technical support is provided for safe operation of a wind power plant.

Description

Technical Field

[0001] This patent belongs to the field of offshore wind power pile monitoring technology and is mainly used for real-time monitoring of scour pits around offshore wind power pile foundations, providing technical support for the safe operation of wind farms. Background Technology

[0002] With the rapid development of the offshore wind power industry, monopile foundations, as the most widely used foundation type, are increasingly facing the problem of localized seabed scouring, which seriously threatens the overall stability and operational safety of wind turbines. Therefore, real-time and accurate monitoring of the scour pit morphology is crucial.

[0003] Currently, the industry has explored various technological approaches to monitor this safety risk. Current monitoring of offshore wind turbine pile scour pits primarily relies on optical fibers, optical sensing, sonar, and piezoelectric sensors to detect changes in the pile's condition caused by scour.

[0004] Fiber Bragg grating sensor technology: This technology can invert the scour profile by measuring the strain of the pile body. However, the sensor deployment is complex, requiring pre-embedding inside the pile body, making it difficult to implement on existing wind turbines. Furthermore, the signal is susceptible to electromagnetic interference and long-term creep, and its reliability needs to be improved. Although optical sensing technology can achieve non-contact measurement, it is highly susceptible to seawater turbidity, microbial adhesion, and harsh sea conditions, resulting in low practical usability.

[0005] Sonar detection technology: It can obtain seabed topography relatively intuitively, but the equipment is expensive, the deployment and maintenance costs are high, and the sound wave signal is prone to noise and multipath interference in complex marine environments, making it difficult to guarantee measurement accuracy;

[0006] Indirect monitoring methods based on tilt or vibration analysis infer scour status by analyzing changes in structural dynamic characteristics. However, the mechanisms are complex, it is difficult to establish an accurate correspondence between vibration response and scour depth, and it is easily affected by the coupling interference of environmental factors such as unit operating load and wave impact. Both sensitivity and accuracy are significantly limited.

[0007] Existing technologies, whether due to reliability, economic efficiency, or implementation difficulty, are insufficient to meet the long-term, stable, high-precision, and cost-controllable monitoring needs of the offshore wind power industry for scour pits. There is an urgent need to develop a new and efficient solution. Summary of the Invention

[0008] The purpose of this invention is to provide a method and system for monitoring the piezoelectricity of seabed scour pits in wind turbine piles based on nanogenerators, so as to solve the problems mentioned in the background art.

[0009] To address the aforementioned technical problems, the present invention provides a photochemically controllable deposition method based on copper-silver bimetallic nanoparticles, comprising the following:

[0010] By burying array sensors on the seabed around the wind turbine piles, piezoelectric units are used to convert the kinetic energy of ocean fluids into electrical energy, and at the same time, the change in the exposed length of the vertical plate of the sensor is converted into a voltage signal.

[0011] The sensor uses reinforced fiber / epoxy resin as a carrier and is coated with corrosion-resistant paint. It is self-powered by piezoelectricity using fluid kinetic energy, and does not require an external power source at all.

[0012] Furthermore, the data is transmitted to a land-based receiving base station via a sea-based relay device, enabling real-time monitoring and early warning. Its multi-layered protective structure ensures stable operation for more than a year in complex marine environments.

[0013] The core of the system includes seabed sensors, a sea surface signal relay module, and a land data processing and early warning system, forming an integrated system of "sensing-power supply-transmission".

[0014] Compared with the prior art, the beneficial effects of the present invention are:

[0015] I. Solving the problem of high ongoing maintenance costs:

[0016] Especially in long-term ocean environments, systems are susceptible to various factors, leading to high deployment costs, difficult maintenance, and insufficient reliability in harsh sea conditions. This project adopts a self-powered design, eliminating the need for an external power source. It utilizes the kinetic energy of ocean currents to drive PVDF piezoelectric units, directly exciting the PVDF to generate corresponding electrical signals. This ensures power supply while simultaneously monitoring seabed scouring. The system boasts comprehensive functionality and a low energy efficiency ratio.

[0017] II. Achieving high-precision and high-sensitivity scour depth monitoring:

[0018] By establishing a precise mapping relationship between the exposed length of the sensor's vertical plate and the output voltage of the piezoelectric unit, this invention can directly convert the physical quantity of scour depth into a precisely measurable electrical signal. This mechanism is highly sensitive and can effectively capture minute changes in scour pits, overcoming the shortcomings of traditional contact or image-based measurement methods in turbid seawater, which suffer from insufficient accuracy and susceptibility to interference. It achieves quantitative and high-precision monitoring of the scour status of wind turbine foundations.

[0019] III. Ensuring the long-term stability of the system in harsh marine environments:

[0020] To address the harsh operating conditions of high pressure, high salinity, high humidity, and marine organism adhesion, this invention employs a composite protective structure consisting of "reinforced fiber / epoxy resin composite material + multi-layer corrosion-resistant coating." This structure combines high strength with excellent corrosion resistance, providing multiple layers of protection for the core sensing and power supply units. This ensures that the sensor can operate stably for more than a year in the complex underwater environment, greatly improving the system's reliability and durability.

[0021] IV. Achieving comprehensive, all-around perception of the flushing status:

[0022] This invention innovatively employs a double-layer circular array to deploy sensors within a 1-meter radius around the wind turbine foundation. This three-dimensional deployment strategy, combined with multi-node data fusion technology, can simultaneously acquire scour data from different locations and depths around the foundation, overcoming the limitations of single-point monitoring. It achieves comprehensive, three-dimensional, and blind-spot-free monitoring of the formation and development of scour pits, providing more comprehensive and reliable data support for foundation safety assessment. Attached Figure Description

[0023] Figure 1 The deployment of a double-layer sensor array around the wind turbine foundation shows 16 sensors in total, with 8 sensors embedded in each layer. The spatial arrangement of the sensors around the foundation is clearly presented, demonstrating the design of the array-style sensor deployment to achieve comprehensive, blind-spot-free scour monitoring.

[0024] Figure 2 For the secondary deployment of the sensor array, after Figure 2 After comprehensive detection, the sensor locations were improved and deployed according to the direction of ocean currents, enabling more precise detection of severely eroded areas.

[0025] Figure 3 This is a sea surface signal relay module, which includes: a sensor, a signal preprocessing module, and a wireless signal transmitter. The sensor and the signal preprocessing module are electrically connected, while the signal preprocessing module and the wireless signal transmitter are soldered together.

[0026] Figure 4 This is a land-based signal receiving module, which includes: a signal processing interface and a wireless signal receiving device. The signal processing interface and the wireless signal receiving device are electrically connected.

[0027] Figure 5 This is a signal processing system. The node positions can be modified arbitrarily, and it will be marked in red as a warning after receiving a wireless signal.

[0028] Figure 6 The circuit diagram of a microcontroller. Figure 3 The signal processing module. Detailed Implementation

[0029] (I) Submarine Signal Output Module

[0030] 1. Components and Description

[0031] This module comprises two key components: sensors and submarine cables. These two components work together to achieve real-time monitoring and data transmission of the pile foundation's condition in a marine environment. The sensor, as the core data acquisition terminal of the system, is structurally designed to be deeply adapted to the complex conditions of high pressure, high salinity, and high humidity in the ocean. Therefore, a piezoelectric element is used as the core sensing element, which converts mechanical deformation into electrical signals to capture changes in the environment surrounding the pile foundation. The sensor body is constructed from reinforced fiber / epoxy resin composite material. This material combines lightweight and high rigidity, effectively resisting the impact of seawater pressure and the instantaneous stress brought by wind and waves. A high-performance corrosion-resistant coating is applied to the outer layer of the composite material, forming a multi-layered protective structure that isolates it from seawater erosion, prevents chloride ion penetration, and reduces marine organism attachment, ensuring long-term stable operation of the sensor. The submarine cable, as the key carrier of signal transmission, adopts a waterproof and pressure-resistant structure to cope with seawater abrasion, salt spray corrosion, and the effects of deep-water pressure. This prevents seawater from seeping into the cable and damaging the conductors and signal lines, while also resisting external mechanical damage, ensuring the reliability of the power supply and data transmission links. In terms of component connection logic, to improve system redundancy and fault tolerance, no direct physical or electrical connection is set between all sensors, and each maintains an independent working state. The failure of a single sensor only affects its own monitoring area and will not cause the overall system to be paralyzed. At the same time, each sensor is connected to the submarine cable through a dedicated electrical interface. This star-shaped distributed connection method can ensure that each sensor is not affected by other sensors, and can accurately transmit the monitoring signals collected by the sensors to the subsequent processing modules, avoiding signal interference and transmission loss.

[0032] During the on-site assembly phase, in order to achieve comprehensive and blind-spot-free monitoring of the environment surrounding the wind turbine pile foundation, the sensors need to be buried in a regular octagonal array around the bottom of the wind turbine pile foundation. The center of the array should coincide with the center of the pile foundation, and the radius of the circumcircle of the octagon should be adapted according to the diameter of the pile foundation to ensure that multiple independent sensors are evenly distributed around the pile foundation, covering a 360° monitoring range. At the same time, the accuracy and firmness of the sensor installation position must be ensured during the burial process to avoid sensor displacement due to marine fluid erosion or silt deposition, thereby ensuring the accuracy of monitoring data and the overall working efficiency of the system.

[0033] After the sensors are assembled and operated for a period of time, a precise monitoring method can be adopted. Five sensors are laid facing the ocean current, and three sensors are laid behind them, targeting the most severely affected areas. After the sensors are assembled and operated for a period of time, the system will analyze the scour depth, flow velocity, and other data in each direction based on the scour data accumulated from the previous comprehensive monitoring. Then, a precise focused installation strategy can be adopted. Combining the ocean current monitoring results, the direction of the main scour force of the ocean current is determined. Five sensors are arranged on the upstream side facing the ocean current to form a high-density detection zone. Each sensor covers a sector of about 30° to capture high-frequency detection of whether the pile foundation is loose. Three sensors are laid at 60° intervals in the area behind and to the side of the ocean current to cover the remaining sectors, taking into account the monitoring of secondary scour induced by ocean eddies.

[0034] 2. Sensor Structure

[0035] The sensor fabricated in this project features a unique multi-layered structure. The main body is a reinforced fiber / epoxy resin composite material prepared using a resin transfer molding process. A metal mold is used, with the inner surface coated with a release agent and reinforced fiber woven mesh laid as a skeleton. A BTO / PVDF piezoelectric sensor unit is pre-placed within the mold. Epoxy resin is injected into the mold through an injection port at a pressure of 0.2-0.5 MPa, filling the gaps between the fiber preforms. The mold is then cured at a constant temperature of 90℃ for 3 hours, forming a unique integrated structure of the composite material and the sensor. Utilizing the closed-mold molding advantages of the resin transfer molding process, a specially designed sensor with an integrated "support-sensing-protection" structure is created, using a reinforced fiber woven mesh as the skeleton, epoxy resin as the main body, and the BTO / PVDF sensor as the core. Simultaneously, the sensor is coated externally with a three-layer waterproof structure consisting of a polyaniline primer, a polyaniline intermediate coat, and a fluorocarbon topcoat. Therefore, this sensor differs from existing sensors in that it can operate stably in extreme marine environments, eliminating concerns about sensor detachment due to ocean currents or corrosion from saltwater.

[0036] 3. Work Process

[0037] The working process of the offshore wind power pile foundation monitoring system is based on a closed loop of "environmental stimulation - energy self-sufficiency - signal acquisition - stable transmission - long-term operation". Relying on the piezoelectric effect and self-powered design, it realizes real-time perception of the scouring effect of marine fluids. At the same time, through material protection and structural optimization, it is adapted to extreme marine environments such as high pressure and high salinity.

[0038] The system's operation originates from the dynamic effects of ocean fluids (such as waves, currents, and tides) on the sensor's vertical plate. In the initial monitoring state, the bottom of the sensor's vertical plate is embedded in a layer of seabed sediment, while the length of its top exposed in the fluid remains stable; at this point, sediment cover and fluid erosion are in dynamic equilibrium. When the ocean fluid dynamics intensify, the shear force on the seabed sediment exceeds a critical value, causing the sediment around the sensor's vertical plate to be eroded layer by layer, with the exposed length increasing synchronously with the intensity of the erosion.

[0039] This change in exposed length directly translates into mechanical stimulation of the piezoelectric element built into the sensor, causing it to undergo minute elastic deformation. At this point, based on the positive piezoelectric effect, under mechanical stress, the relative displacement of the positive and negative charge centers within the piezoelectric material polarizes, resulting in bound charges on the surface and generating a voltage signal. The piezoelectric element outputs a DC voltage signal that precisely corresponds to the exposed length, which is then transmitted via a submarine cable to a signal relay module on the sea surface. Therefore, unlike other traditional sensors that rely on external cables for power, the piezoelectric sensor in this system requires no external power supply, enabling long-term unattended operation.

[0040] (II) Sea surface signal relay module

[0041] 1. Components and Description

[0042] This module mainly consists of three core components: a signal preprocessing module, a wireless signal transmitting device, and a power supply module. These components work together in terms of function and structure to ensure the stable operation of the equipment.

[0043] Regarding the connections between components, the signal preprocessing module, as the core control and data relay hub of the equipment, establishes stable electrical connections with both the wireless signal transmitter and the power supply module. To ensure the reliability of the connections, the signal preprocessing module and the wireless signal transmitter are welded together; simultaneously, the signal preprocessing module transmits data with the underwater sensor via a submarine cable.

[0044] During assembly, the above-mentioned connection relationships must be strictly followed to complete the assembly of each component. The water surface location for installation must be carefully considered, with priority given to locations with gentle water flow to prevent displacement or damage to the equipment due to water impact or external collisions. At the same time, a signal coverage test must be conducted on the proposed installation area before installation to ensure that the installation location is within the effective coverage range of the antenna signal transmission. If there are obstacles such as floating objects or bridge piers that may block the signal, the antenna installation height must be adjusted appropriately, and a signal gain device may be added if necessary. This will ensure that the wireless signal can be stably transmitted to the target receiving station, thus fully guaranteeing the operational performance of the equipment in practical applications.

[0045] 2. Work Process

[0046] In this device, the signal preprocessing module, as a key link in data processing, is mainly composed of a circuit board. The board has multiple electronic components and interfaces, including filter capacitors, data conversion chips, and adapters, soldered on it. These components and interfaces work together to preprocess the raw signals transmitted by the sensors, ensuring the accuracy of subsequent signal transmission. The wireless signal transmitter currently uses the TP1110-MK20 module, which has good transmission and anti-interference capabilities. If the actual application scenario has special requirements for transmission distance, frequency band, or power consumption, it can be replaced with other models of modules that match the interface and communication protocol.

[0047] The power supply module is responsible for providing continuous power to the entire device. This module uses both solar and hydropower. The hydropower module was self-made for this project, while the solar power system consists of solar panels, an MPPT solar management module, and batteries. This method enables the system to be self-powered by using solar energy and a hydropower generator to charge the batteries, which in turn power the signal preprocessing module. The power supply module can also utilize the batteries to ensure continuous operation. Therefore, even if solar energy is unavailable for extended periods, the hydropower module can withstand prolonged extreme weather conditions at sea, ensuring the sensor's normal operation.

[0048] The electrical signals generated by the seabed sensor are transmitted to the signal preprocessing module via a dedicated seabed cable. The preprocessing module amplifies, filters, and performs analog-to-digital conversion on the weak piezoelectric signals, converting the analog signals into digital signals. The converted digital signals are then transmitted to the surface signal transmitter, which transmits the data to the land base station via a high-gain antenna using wireless communication.

[0049] (III) Land-based signal receiving module

[0050] 1. Components and Description

[0051] The core components of this monitoring system include a wireless signal receiving device and a signal processing system, along with their supporting equipment. These two components work together to receive, process, and manage sea surface monitoring signals. The wireless signal receiving device consists of an antenna module and a signal processing module. The antenna module efficiently captures wireless signals transmitted from the sea surface, while the signal processing module performs preliminary filtering and signal conditioning on the received raw signals, laying the foundation for subsequent data processing. The signal processing system is developed using STM32 programming, possessing strong flexibility and adaptability, and can well adapt to the processing logic of monitoring data. This system is directly installed on the data processing equipment, currently a computer. As a common device, computers offer significant advantages in terms of ease of operation and daily maintenance. Regarding the connection between the components, the wireless signal receiving device and the data processing equipment are connected via a USB interface. This connection method offers plug-and-play convenience and transmission stability, facilitating daily connection debugging and maintenance operations by staff, and ensuring smooth signal transmission. Regarding installation requirements, the location of terrestrial base stations needs careful consideration. Priority should be given to areas with open views and no tall buildings or dense vegetation obstructing the view, while avoiding strong electromagnetic interference sources. This ensures that the wireless receiving antenna can stably and effectively receive the transmitted signals from the sea surface, avoiding signal attenuation or loss due to obstruction or interference. Data processing equipment must be guaranteed to be used stably and effectively for a long time. Its storage capacity must be equipped with sufficient hard disk space to accommodate large-scale monitoring data accumulated over a long period of time. Its computing power must be equipped with a processor with suitable performance to ensure that data parsing, processing and storage operations can be smoothly completed when processing and managing monitoring data for a long time, meeting the actual needs of long-term large-scale monitoring data management.

[0052] 2. Work Process

[0053] The high-sensitivity wireless receiving antenna of the land-based station receives the monitoring data transmitted by the sea surface in real time. This antenna can accurately capture the weak monitoring signals transmitted from a long distance on the sea surface. The signal processing system配套 with the antenna then conducts professional processing on the received signals. Since the system采用 redundant design and includes two receiving channels, the main and the backup, when the main channel fails, the backup channel can quickly switch and be put into use, effectively improving the operation reliability of the entire system and ensuring that the signal processing process is not interrupted. The processed signals will be stably transmitted to the data processing server. The server first decodes the received signals, converting the encoded signals into recognizable data formats, and then排查 possible errors in the data transmission process through the verification mechanism. Finally, it completes the secure storage of the data, ensuring that there are no deviations or losses in the data during transmission and storage. The data processing system then conducts real-time analysis and calculation on the stored monitoring data based on the algebraic relationship model预先 established between the scour depth and the voltage signal, accurately calculating the scour depth around the current pile foundation. At the same time, the system is equipped with a visualization interface, on which the scour status of each monitoring point, the historical data change curve, and the future trend prediction are clearly displayed, enabling the operation and maintenance personnel to intuitively and clearly grasp the real-time safety status of the pile foundation. In addition, the warning system in the system预先 sets multiple warning thresholds. When the monitoring data exceeds the threshold of the corresponding level, it will automatically trigger the warning mechanism and timely传递 warning information to the relevant responsible personnel so that corresponding measures can be quickly taken.

[0054] (IV) Alternative Solutions

[0055] 1. Sensor Array Replacement: The array form can be adjusted according to the seabed environment. For example, a linear array can be used in areas with complex ocean currents, or the number of sensors can be increased to improve the monitoring density.

[0056] 2. Material Replacement: The piezoelectric unit can use BTO / PVDF composite materials (with both high piezoelectricity and flexibility) to further enhance the signal strength.

[0057] 3. Protective Coating Replacement: The protective coating can be replaced with other corrosion-resistant materials to adapt to different marine corrosion conditions. The protective coatings mainly include metal coatings, organic coatings, ceramic coatings, composite coatings, etc. Metal coatings include zinc-aluminum-graphene composite layers, thermal-sprayed metal coatings, etc. Organic coatings such as epoxy resin coatings, polyurethane elastomers, polyurea elastomers, etc. Ceramic coatings include nano-ceramic sealing layers, tungsten carbide coatings, etc. There are many types of composite coatings, such as a three-layer composite system (zinc-aluminum-graphene + nano-ceramic + polyurethane), organic / inorganic fiber composite reinforced coatings, and other composite materials.

[0058] 4. Power Alternatives: The signal relay module can be powered by other methods, primarily through traditional and new energy sources. Traditional energy sources include small fuel generators or batteries. New energy solutions include connecting to wind power systems or using ocean tidal power.

[0059] 5. Signal transmission replacement: Other WiFi modules or Bluetooth modules can be used instead. The antenna can be replaced with other antennas with higher performance and longer transmission distance.

[0060] 6. Other applications: This system can be extended to monitor the scour or displacement of underwater structures such as bridge pile foundations and submarine pipelines. It can be adapted to different scenarios by adjusting the sensor size and deployment method.

Claims

1. A marine scour monitoring system, characterized in that, The application relates to a self-powered module based on a PVDF piezoelectric unit, a high-sensitivity monitoring module (3), a multi-layer protection structure, a "sensing-power-transmission" integrated module and an array sensor (1) adapted to marine environment, wherein the self-powered module based on the PVDF piezoelectric unit is used for converting marine fluid kinetic energy into electric energy to provide power for the system; the high-sensitivity monitoring module (3) is used for establishing a mapping relationship between a bare length of a vertical plate of the sensor and an output voltage of the PVDF piezoelectric unit, and realizing scour depth monitoring; the multi-layer protection structure is used for guaranteeing stable operation of the system in a complex marine environment; the "sensing-power-transmission" integrated module is used for integrating the sensor unit, the self-powered module, a signal preprocessing module (3) and a transmission interface, and realizing full-process autonomous operation; and the array sensor adapted to the marine environment is used for being arranged around a wind power pile foundation to realize omnibearing scour monitoring.

2. A marine erosion monitoring system according to claim 1, wherein, The self-powered module based on the PVDF piezoelectric unit directly converts marine fluid kinetic energy into electric energy through the PVDF piezoelectric unit to construct an autonomous power supply system without external power supply.

3. A marine erosion monitoring system according to claim 1, wherein, The high-sensitivity monitoring module establishes the mapping relationship between the bare length of the vertical plate of the sensor and the output voltage of the PVDF piezoelectric unit, and can realize high-precision scour depth monitoring with an error of less than 5 cm.

4. A marine erosion monitoring system according to claim 1, wherein, The multi-layer protection structure is a composite protection structure of "reinforced fiber / epoxy resin composite material + multi-layer corrosion-resistant coating", and can guarantee stable operation of the system in a complex environment of high pressure, high salt, high humidity and marine biological attachment for more than one year.

5. A marine erosion monitoring system according to claim 1, wherein, The "sensing-power-transmission" integrated module integrates the sensor unit, the self-powered module, the signal preprocessing module and the transmission interface in a compact structure, and realizes full-process autonomous operation from scour signal collection, energy supply to data transmission.

6. A marine erosion monitoring system according to claim 1, wherein, The array sensor adapted to the marine environment is arranged in a double-layer circular array within a range of 1 m around the wind power pile foundation, and realizes omnibearing and dead-angle-free scour monitoring through multi-node data fusion.

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