Active wind turbine blade load suppression system based on aeroelastic effect

Abstract

The invention relates to the technical field of wind power generation, and discloses an active wind turbine blade load suppression system based on an aeroelastic effect, which comprises a flexible structure module, an execution and energy recovery module, a sensing and state estimation module and a control and energy management module, in the active driving mode, the control and energy management module pumps working fluid into the flexible structure module integrated on the rear edge of the blade according to sensing data and the instruction execution and energy recovery module, so that the flexible structure module deforms to change the aerodynamic configuration of the blade, and therefore the load is restrained. According to the system, working fluid discharged from the flexible structure module during passive deformation of the blades is used for driving the execution and energy recovery module to carry out energy conversion, and recovered electric energy is stored. Through mode switching and energy closed loop of active driving and passive energy recovery, the energy efficiency and self-sustaining capability of the system are improved, accurate and efficient load suppression is achieved, and the system is compact in structure and high in reliability.

Description

Technical Field

[0001] This invention relates to the field of wind power generation technology, specifically to an active wind turbine blade load suppression system based on aeroelastic effects. Background Technology

[0002] During operation, wind turbine blades are subjected to complex unsteady aerodynamic loads caused by wind shear, turbulence, gusts, and tower shadow effects. These drastic fluctuations in load are not only a major cause of fatigue damage to the blade structure and a shortened service life, but also limit the development of blades towards longer and more flexible designs.

[0003] To mitigate this problem, existing technologies mainly employ two approaches: passive control and active control. Passive control technologies, such as achieving bending-torsional coupling through aeroelastic shearing of materials, are typically designed for specific operating conditions. Therefore, their adaptability is limited when wind conditions are variable, and they struggle to effectively respond to sudden extreme loads.

[0004] Active control technology, by introducing sensors, controllers, and actuators, can adjust the aerodynamic characteristics of blades according to real-time wind conditions. However, traditional variable pitch control technology, which requires driving the entire blade, suffers from high system inertia, narrow response bandwidth, and poor performance in suppressing high-frequency turbulent loads. To address this issue, various local active flow control technologies have been developed, such as trailing edge flaps and synthetic jets. These technologies offer fast response times and effectively suppress high-frequency loads. However, existing trailing edge flaps and similar devices largely rely on traditional electromechanical actuators such as motors and hydraulic cylinders, resulting in complex mechanical structures and reliability and maintainability issues. More importantly, these active control systems continuously consume energy during operation, drawing energy from generator output, thus reducing the generator's net power generation efficiency. Current technologies generally lack effective management of the system's own energy consumption and mechanisms for recovering and utilizing energy from the external environment, resulting in insufficient energy self-sufficiency. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides an active wind turbine blade load suppression system based on aeroelastic effects, which solves the problem that existing active blade load suppression systems only consume energy and cannot recover energy, resulting in low system energy efficiency and insufficient self-sufficiency.

[0006] To achieve the above objectives, the present invention provides the following technical solution: an active wind turbine blade load suppression system based on aeroelastic effects, comprising: A flexible structural module is integrated into the trailing edge of a wind turbine blade. The flexible structural module is composed of at least one flexible composite material cell. The flexible composite material cell defines a sealed fluid chamber for containing working fluid. The flexible structural module is configured to deform when the pressure inside the fluid chamber changes. An execution and energy recovery module, which is in fluid communication with the fluid chamber, is configured to pump the working fluid into the fluid chamber in active drive mode to increase the internal pressure, and to recover energy using the working fluid discharged from the fluid chamber in energy recovery mode. The sensing and state estimation module is configured to monitor the operating state of the wind turbine blades in real time to generate sensing data. The control and energy management module is signal-connected to the sensing and state estimation module and the execution and energy recovery module, respectively. It is configured to generate control commands based on the sensing data to control the execution and energy recovery module to switch between the active drive mode and the energy recovery mode, and to manage the recovered energy.

[0007] Preferably, the flexible composite cell includes an upper wall, a lower wall, and internal reinforcing ribs connecting the upper and lower walls; the internal reinforcing ribs are asymmetrically distributed within the fluid cavity so that the flexible composite cell undergoes bending deformation, primarily changing the airfoil camber, when subjected to internal pressure.

[0008] Preferably, the execution and energy recovery module includes a piezoelectric stack pump for operation in the active drive mode. The piezoelectric stack pump includes a piezoelectric stack actuator that generates high-frequency reciprocating motion according to the control command to pump the working fluid into the fluid chamber.

[0009] Preferably, the execution and energy recovery module includes a bidirectional piezoelectric energy converter for operation in the energy recovery mode, the bidirectional piezoelectric energy converter including a piezoelectric element configured to convert the pressure energy of the working fluid discharged from the fluid chamber into electrical energy.

[0010] Preferably, the execution and energy recovery module further includes a hydraulic fluid circuit and a high-speed electronically controlled switching valve controlled by the control and energy management module. The high-speed electronically controlled switching valve is used to switch the flow path of the working fluid according to the control command, so as to realize the switching between the active drive mode and the energy recovery mode.

[0011] Preferably, the sensing and state estimation module includes a fiber optic strain sensor arranged along the spanwise direction of the wind turbine blade for measuring the surface strain distribution of the wind turbine blade.

[0012] Preferably, the sensing and state estimation module includes an acoustic resonance pressure sensor integrated into the hydraulic fluid circuit of the execution and energy recovery module, used to determine the fluid pressure in the fluid chamber by monitoring the shift in the resonant frequency.

[0013] Preferably, the main controller within the control and energy management module is configured to run a load suppression control algorithm based on a state-space model, and calculate the control command by minimizing a performance index function that includes load suppression effect and control energy consumption.

[0014] Preferably, the control and energy management module further includes an energy storage unit and an energy management unit; the energy management unit is configured to store the electrical energy recovered by the execution and energy recovery module in the energy recovery mode into the energy storage unit, and to extract energy from the energy storage unit in the active drive mode.

[0015] Preferably, the control and energy management module is configured to decide whether to execute the active drive mode or the energy recovery mode based on the load level determined by the sensor data and the energy state of the energy storage unit.

[0016] This invention provides an active wind turbine blade load suppression system based on aeroelastic effects. It offers the following advantages: 1. This invention, by incorporating an execution and energy recovery module as well as a control and energy management module, enables the system to not only possess active drive capability but also enter an energy recovery mode when the blades undergo passive deformation. A bidirectional piezoelectric energy converter converts a portion of the mechanical energy from blade vibration into electrical energy and stores it in an energy storage unit for subsequent consumption in the active drive mode. This internal energy recycling significantly reduces the system's dependence on the wind turbine's own power supply system, improving the system's overall energy efficiency and self-sufficiency.

[0017] 2. This invention employs a sensing and state estimation module to accurately perceive the blade state in real time, and combines this with an advanced control algorithm based on a state-space model and performance index function in the control and energy management module. This enables the calculation of the optimal control command that balances load suppression effectiveness and control energy consumption. This allows the system to respond quickly, accurately, and efficiently to changing external aerodynamic loads, achieving load suppression performance superior to traditional passive or simple on / off control.

[0018] 3. The flexible structural module used in this invention is integrated with the trailing edge of the blade, and the piezoelectric stack pump and bidirectional piezoelectric energy converter in the energy recovery module are both solid-state devices. This design avoids the complex rotating parts, long-distance high-pressure oil pipes, and large hydraulic sources contained in traditional hydraulic or electromechanical systems, making the overall system structure more compact, lighter, and more reliable, thereby reducing installation difficulty and subsequent maintenance costs. Attached Figure Description

[0019] Figure 1 This is a system architecture diagram of the present invention. Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Please see the appendix Figure 1 This invention provides an active wind turbine blade load suppression system based on aeroelastic effects, comprising: A flexible structural module is integrated into the trailing edge of a wind turbine blade. The flexible structural module consists of at least one flexible composite material cell. The flexible composite material cell defines a sealed fluid chamber for containing working fluid. The flexible structural module is configured to deform in response to changes in the internal pressure of the fluid chamber. In this embodiment, the flexible structure module constitutes the adaptive flexible trailing edge of the blade and is the physical entity responsible for system deformation. The execution and energy recovery module drives the flexible structure module to deform according to instructions and recovers energy under specific operating conditions. The sensing and state estimation module is used to monitor the structural state and external load information of the blade in real time. The control and energy management module, as the system's decision-making and scheduling center, receives data from the sensing and state estimation module, issues instructions to the execution and energy recovery module, and manages the system's energy.

[0022] During system operation, the dynamic behavior of the flexible structural module can be described by the following structural dynamics equation. This equation establishes the relationship between external aerodynamic forces, internal driving forces, and structural response.

[0023] ; in: The mass matrix of the flexible structure module; The damping matrix of the flexible structure module; Here is the stiffness matrix of the flexible structural module; For flexible structural modules in time The nodal displacement vector; For flexible structural modules in time The nodal velocity vector is the first derivative of the nodal displacement vector with respect to time; For flexible structural modules in time The nodal acceleration vector is the second derivative of the nodal displacement vector with respect to time; The unsteady aerodynamic load vector acts on the outer surface of the flexible structure module. This load is monitored and estimated by the sensing and state estimation module. The equivalent nodal force vector of the internal pressure generated by the execution and energy recovery module is the control input applied to the flexible structure module.

[0024] The collaborative working relationships between the modules are as follows: The sensing and state estimation module will include... The measured data is transmitted to the control and energy management module. Based on a preset control law, the control and energy management module calculates the target control force required to counteract or suppress aerodynamic loads and generates commands accordingly. The execution and energy recovery module receives these commands and generates the actual internal pressure equivalent nodal force. It acts on the flexible structural module, causing it to deform, thereby changing the local aerodynamic shape of the trailing edge of the blade and achieving the purpose of suppressing the load.

[0025] The execution and energy recovery module is in fluid communication with the fluid chamber and is configured to pump working fluid into the fluid chamber to increase the internal pressure in active drive mode and to recover energy using the working fluid discharged from the fluid chamber in energy recovery mode. In active drive mode, the control and energy management module applies a high-frequency drive voltage to the piezoelectric stack actuator. Based on the inverse piezoelectric effect, the piezoelectric stack actuator generates an axial expansion and contraction displacement proportional to the voltage. : ; in: For piezoelectric stack actuators in time axial displacement; The effective number of stacked layers for the piezoelectric stacked actuator; The longitudinal piezoelectric strain constant of the piezoelectric material; The applied driving voltage.

[0026] This displacement drives the piston to reciprocate within the pump chamber, changing its volume. Under the coordinated action of the inlet and outlet check valves, fluid is unidirectionally drawn into the reservoir and pumped out into the hydraulic fluid circuit. At a driving frequency of... At that time, the volumetric flow rate generated for: ; in: The volumetric flow rate output by the piezoelectric stacked pump at time t; The frequency of the driving voltage; This is the equivalent cross-sectional area for driving the piston.

[0027] The bidirectional piezoelectric energy converter is the core component of energy recovery, which includes a piezoelectric element, a force-receiving piston, and a fluid channel through which fluid flows.

[0028] In energy recovery mode, when the flexible structural module is compressed by external aerodynamic forces, the fluid within the flexible composite material cells is extruded, creating a high-pressure recirculation. This recirculation is guided into the fluid channels of the bidirectional piezoelectric energy converter. The instantaneous pressure of the fluid... A force is applied to the piezoelectric element by a force-receiving piston. : ; in: The force exerted on the piezoelectric element at time t; The instantaneous pressure of the fluid flowing through the converter; This represents the effective force-bearing area of ​​the piston.

[0029] Based on the positive piezoelectric effect, this force causes the piezoelectric element to generate an electric charge. : ; in: For piezoelectric elements in time The generated charge.

[0030] The charge is collected by the energy management unit and stored in the energy storage unit.

[0031] The hydraulic fluid circuit connects the piezoelectric stack pump, the bidirectional piezoelectric energy converter, the flexible composite cell, and the reservoir. This circuit is filled with working fluid. A high-speed electrically controlled switching valve is installed in the circuit. This valve, controlled by the control and energy management module, selects the fluid circulation path. In active drive mode, the switching valve connects the outlet of the piezoelectric stack pump to the inlet of the flexible composite cell, forming the active drive pipeline. In energy recovery mode, the switching valve connects the outlet of the flexible composite cell to the inlet of the bidirectional piezoelectric energy converter, forming the energy recovery pipeline.

[0032] The sensing and state estimation module is configured to monitor the operating status of the wind turbine blades in real time to generate sensing data. The distributed sensor network includes fiber Bragg grating strain sensors laid along the blade spanwise, and accelerometers installed at key nodes inside the blade. The fiber Bragg grating strain sensors measure the strain distribution on the blade surface, and by analyzing the strain data, the real-time deformation and bending moment of the blade can be reconstructed. Its working principle is based on the Bragg wavelength. With fiber axial strain The change in . This relationship can be described by the following formula: ; in: This represents the center wavelength shift of the fiber optic strain sensor. This is the initial center wavelength of the fiber optic strain sensor; The effective elastic-optical coefficient of the optical fiber material; This represents the axial strain experienced by the optical fiber.

[0033] Accelerometers are used to measure the high-frequency vibration response of blades, providing data for identifying and suppressing vibrations at specific frequencies.

[0034] In one embodiment, the sensing and state estimation module further includes an acoustic resonance pressure sensor integrated into the hydraulic fluid circuit for self-sensing of the fluid pressure inside the flexible composite material cell. The high-frequency pressure pulses generated during the operation of the piezoelectric stack pump serve as an excitation signal, stimulating the acoustic resonance pressure sensor. The average static pressure within the fluid chamber... This will affect the physical properties of the working fluid, thereby changing the resonant frequency of the acoustic resonance pressure sensor. By monitoring the shift in resonant frequency It can inversely determine the pressure within the fluid chamber. This relationship can be represented as: ; in, It is a mapping function determined through experimental calibration.

[0035] The control and energy management module in this invention is the core of the system's calculation and decision-making. This module may include a control and energy management unit, which can integrate a main controller, a drive signal generator, an energy management unit (PMU), and an energy storage unit in its hardware.

[0036] The main controller runs a load suppression control algorithm, calculating the optimal control command based on the input from the sensing and state estimation modules. The drive signal generator, according to the main controller's commands, generates the high-frequency, high-voltage electrical signal required to drive the piezoelectric stack pump. The energy management unit manages the bidirectional flow of system energy. Energy storage units, such as supercapacitor arrays, store recovered electrical energy and provide peak power.

[0037] The main controller employs a control algorithm based on a state-space model. The multiphysics coupling behavior of the system can be described by the following set of state-space equations: ; in: The system state vector contains key modal coordinates of the blade structure and state variables such as fluid pressure within the flexible composite material cell. To control the input vector, i.e., the driving voltage applied to the piezoelectric stack pump. ; This is the external disturbance vector, mainly representing the unknown aerodynamic load; The system measurement output vector includes strain values ​​measured by fiber optic strain sensors, etc. A, B, C, D, E are state matrices describing the dynamic characteristics of the system.

[0038] The goal of the control algorithm is to minimize a pre-defined performance metric function J, which combines load suppression effectiveness with control energy consumption. ; in: and Here, are the weight matrices for the output error and control input, respectively, and T represents the optimization time domain. The main controller obtains the optimal control input by solving this optimization problem online. .

[0039] The control and energy management module is connected to the sensing and state estimation module and the execution and energy recovery module respectively. It is configured to generate control commands based on sensing data to control the execution and energy recovery module to switch between active drive mode and energy recovery mode, and to manage the recovered energy. In an active load mitigation workflow, the sensing and state estimation module first monitors the blade's state in real time. When the fiber optic strain sensor or accelerometer detects an aerodynamic load exceeding a preset load threshold caused by gusts or other factors, the relevant data is transmitted to the control and energy management module.

[0040] The main controller receives and processes sensor data, based on the state-space model and performance index function. Based on the optimization results, the optimal control input required to suppress the load is calculated. It then generates corresponding drive commands. Simultaneously, the energy management unit assesses the energy in the energy storage unit. Is it higher than the minimum working threshold? .

[0041] If sufficient energy is available, the main controller sends a command to the high-speed electronically controlled switching valve, causing it to switch to the position connected to the active drive pipeline. Simultaneously, the drive signal generator applies a drive voltage to the piezoelectric stack pump according to the command. The piezoelectric stack pump operates, pumping the working fluid into the fluid chamber of the flexible composite cell.

[0042] The increase in pressure within the fluid chamber causes the flexible structural module to undergo a pre-set bending deformation, thereby changing the local aerodynamic shape of the blade's trailing edge and generating an aerodynamic force opposite to the external disturbance load, ultimately suppressing the load on the blade.

[0043] In a passive energy recovery workflow, when the sensing and state estimation module detects that the blades are undergoing rapid passive deformation caused by external loads, and this deformation leads to the compression of the flexible composite material cells, the main controller identifies this condition as an energy recovery opportunity. Simultaneously, the energy management unit assesses the energy in the energy storage unit. Is it below the maximum storage threshold? .

[0044] If the storage capacity is not full, the main controller sends a command to the high-speed electronically controlled switching valve to switch it to the position connected to the energy recovery pipeline. The high-pressure working fluid squeezed out when the flexible composite cell is compressed flows to the bidirectional piezoelectric energy converter through the energy recovery pipeline.

[0045] Fluid pressure drives the piezoelectric element within the bidirectional piezoelectric energy converter to generate an electric charge. The energy management unit collects, rectifies, and regulates this charge, storing the converted electrical energy in an energy storage unit for use in subsequent active drive modes.

[0046] The system's operating mode is dynamically switched by the control and energy management module based on real-time operating conditions. Its collaborative control logic is as follows: When it is necessary to actively suppress the load and At this time, the system enters active drive mode.

[0047] When an available passive deformation is detected and At that time, the system enters energy recovery mode.

[0048] Under other operating conditions, the system enters standby mode. In this mode, the high-speed electronically controlled switching valve can be in the bypass position to minimize the damping of the hydraulic fluid circuit, thereby reducing the impact on the conventional aerodynamic performance of the blades.

[0049] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An active wind turbine blade load suppression system based on aeroelastic effects, characterized in that, include: A flexible structural module is integrated into the trailing edge of a wind turbine blade. The flexible structural module is composed of at least one flexible composite material cell. The flexible composite material cell defines a sealed fluid chamber for containing working fluid. The flexible structural module is configured to deform when the pressure inside the fluid chamber changes. An execution and energy recovery module, which is in fluid communication with the fluid chamber, is configured to pump the working fluid into the fluid chamber in active drive mode to increase the internal pressure, and to recover energy using the working fluid discharged from the fluid chamber in energy recovery mode. The sensing and state estimation module is configured to monitor the operating state of the wind turbine blades in real time to generate sensing data. The control and energy management module is signal-connected to the sensing and state estimation module and the execution and energy recovery module, respectively. It is configured to generate control commands based on the sensing data to control the execution and energy recovery module to switch between the active drive mode and the energy recovery mode, and to manage the recovered energy.

2. The active wind turbine blade load suppression system based on aeroelastic effect according to claim 1, characterized in that, The flexible composite cell includes an upper wall, a lower wall, and internal reinforcing ribs connecting the upper and lower walls; the internal reinforcing ribs are asymmetrically distributed within the fluid chamber so that the flexible composite cell undergoes bending deformation, primarily changing the airfoil camber, when subjected to internal pressure.

3. The active wind turbine blade load suppression system based on aeroelastic effect according to claim 1, characterized in that, The execution and energy recovery module includes a piezoelectric stack pump for operation in the active drive mode. The piezoelectric stack pump includes a piezoelectric stack actuator that generates high-frequency reciprocating motion according to the control command to pump the working fluid into the fluid chamber.

4. The active wind turbine blade load suppression system based on aeroelastic effect according to claim 1, characterized in that, The execution and energy recovery module includes a bidirectional piezoelectric energy converter for operation in the energy recovery mode. The bidirectional piezoelectric energy converter includes a piezoelectric element configured to convert the pressure energy of the working fluid discharged from the fluid chamber into electrical energy.

5. The active wind turbine blade load suppression system based on aeroelastic effect according to claim 1, characterized in that, The execution and energy recovery module also includes a hydraulic fluid circuit and a high-speed electronically controlled switching valve controlled by the control and energy management module. The high-speed electronically controlled switching valve is used to switch the flow path of the working fluid according to the control command, so as to realize the switching between the active drive mode and the energy recovery mode.

6. The active wind turbine blade load suppression system based on aeroelastic effect according to claim 1, characterized in that, The sensing and state estimation module includes fiber optic strain sensors arranged along the spanwise direction of the wind turbine blade, used to measure the surface strain distribution of the wind turbine blade.

7. The active wind turbine blade load suppression system based on aeroelastic effect according to claim 1, characterized in that, The sensing and state estimation module includes an acoustic resonance pressure sensor integrated into the hydraulic fluid circuit of the execution and energy recovery module, used to determine the fluid pressure in the fluid chamber by monitoring the shift in the resonant frequency.

8. The active wind turbine blade load suppression system based on aeroelastic effect according to claim 1, characterized in that, The main controller within the control and energy management module is configured to run a load suppression control algorithm based on a state-space model, and calculates the control command by minimizing a performance index function that includes load suppression effect and control energy consumption.

9. The active wind turbine blade load suppression system based on aeroelastic effect according to claim 1, characterized in that, The control and energy management module further includes an energy storage unit and an energy management unit; the energy management unit is configured to store the electrical energy recovered by the execution and energy recovery module in the energy recovery mode into the energy storage unit, and to extract energy from the energy storage unit in the active drive mode.

10. The active wind turbine blade load suppression system based on aeroelastic effect according to claim 9, characterized in that, The control and energy management module is configured to decide whether to execute the active drive mode or the energy recovery mode based on the load level determined by the sensor data and the energy state of the energy storage unit.

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