Variable pitch control method and system of wind turbine generator

Abstract

The invention discloses a variable pitch control method and system of a wind turbine generator, and belongs to the technical field of wind power generation. The method is applied to a variable pitch control system of the wind turbine generator, the system comprises multiple hardware sensing devices, a control decision device, an SIC variable pitch driving device and a variable pitch execution device, and the method comprises the steps that operation parameters of the wind turbine generator are obtained through the multiple hardware sensing devices; wherein the operation parameters of the wind turbine generator comprise at least one of the following items: the rotating speed of an impeller, the vibration acceleration of a tower drum and bus voltage; determining whether the operation parameters conform to corresponding constraint conditions or not through a control decision-making device; if the operation parameters meet the constraint conditions, a first decision module in the control decision device controls a variable pitch execution device to execute variable pitch operation through an SIC variable pitch driving device; wherein the first decision-making module realizes variable pitch operation through FPGA (Field Programmable Gate Array) control.

Description

Technical Field

[0001] This application and the field of wind power generation technology particularly relate to a pitch control method and system for wind turbine generators. Background Technology

[0002] Currently, wind turbines use PID (proportional-integral-derivative) software control algorithms to perform pitch control. However, PID software control algorithms suffer from slow response and poor safety when dealing with various wind conditions (such as turbulent wind conditions).

[0003] Therefore, there is an urgent need for a pitch control scheme that can shorten response time and improve safety under various wind conditions. Summary of the Invention

[0004] The purpose of this application is to provide a pitch control method and system for wind turbine generators, which can shorten response time and improve safety when performing pitch control operations.

[0005] To address the aforementioned technical problems, the first aspect of this application provides the following technical solution: A pitch control method for a wind turbine includes: a pitch control system applied to the wind turbine, the wind turbine pitch control system including: multiple hardware sensing devices, a control decision device, a SiC pitch drive device, and a pitch actuator; the pitch control method includes: acquiring the operating parameters of the wind turbine through multiple hardware sensing devices; wherein, the operating parameters of the wind turbine include at least one of the following: rotor speed, tower vibration acceleration, and bus voltage; determining whether the operating parameters meet the corresponding constraints through the control decision device; if the operating parameters meet the constraints, then the first decision module in the control decision device controls the pitch actuator to perform a pitch operation through the SiC pitch drive device; wherein, the first decision module implements the pitch operation through FPGA control.

[0006] Optionally, the various hardware sensing devices include at least one of the following: a first sensor is installed on the rear end of the wind turbine motor to collect the rotor speed; a second sensor is installed on the main shaft and gearbox of the wind turbine to collect the tower vibration acceleration; and a third sensor is installed on the DC bus of the wind turbine to collect the bus voltage.

[0007] Optionally, the pitch control system of the wind turbine also includes a capacitor module, and the pitch control method of the wind turbine also includes: if the bus voltage is less than a preset voltage threshold, disconnecting the emergency feathering command EFC power supply connected to the enable terminal of the SIC pitch drive device, and establishing a connection between the enable terminal and the capacitor module.

[0008] Optionally, various hardware sensing devices also include a lidar mounted on the top of the nacelle. The pitch control method for the wind turbine also includes: if the operating parameters do not meet the constraints, the second decision module in the control decision device determines the optimal pitch angle based on the aerodynamic model of blade element momentum theory and the tip speed ratio; wherein, the tip speed ratio is determined by the wind speed and rotor speed collected by the lidar, and the second decision module is used to realize pitch operation through adaptive predictive control (APC); and determine the compensation amount of the pitch angle according to the wind speed and the dynamic inverse controller; generate a feathering command according to the optimal pitch angle and the compensation amount of the pitch angle, and the feathering command is used to instruct the pitch actuator to perform pitch operation through the SIC pitch drive device.

[0009] Optionally, the pitch control method for wind turbine units further includes: determining the SOH value of the capacitor module; and determining the charging and discharging strategy for the capacitor module based on the SOH value.

[0010] Optionally, the charging and discharging strategy for the capacitor module is determined based on the SOH value, including: determining whether the SOH value meets the corresponding threshold; if the SOH value meets the corresponding threshold, then setting the maximum charging current value to a first current value; wherein the maximum charging current value is greater than the first current value.

[0011] Optionally, the various hardware sensing devices also include a temperature sensor installed on the DC bus, which determines the charging and discharging strategy for the capacitor module based on the SOH value, and further includes: determining whether the SOH value meets the corresponding threshold; if the SOH value meets the corresponding threshold, setting the maximum charging current value to a first current value; wherein the maximum charging current value is greater than the first current value; determining whether the operating temperature of the capacitor module meets the corresponding temperature threshold; wherein the operating temperature is acquired by a temperature sensor; if the operating temperature meets the corresponding temperature threshold, charging the capacitor module using a preset pulse method.

[0012] Optionally, the pitch actuator includes at least two permanent magnet synchronous motors and blades, wherein the at least two permanent magnet synchronous motors are connected by backlash-free gear meshing.

[0013] Optionally, the various hardware sensing devices also include a current sensor mounted on the DC bus, and the pitch control method for the wind turbine further includes: determining the performance degradation coefficient of each of at least two permanent magnet synchronous motors; wherein the performance degradation coefficient is determined based on the shaft current of each permanent magnet synchronous motor, the shaft current being acquired by a current sensor; determining a target permanent magnet synchronous motor from the at least two permanent magnet synchronous motors according to the performance degradation coefficient, and having the target permanent magnet synchronous motor perform the pitch operation.

[0014] To address the aforementioned technical problems, the second aspect of this application provides the following technical solution: A pitch control system for a wind turbine includes: multiple hardware sensors, a control decision unit, a SiC pitch drive unit, and a pitch actuator; wherein the multiple hardware sensors are used to acquire operating parameters of the wind turbine; wherein the operating parameters of the wind turbine include at least one of the following: rotor speed, tower vibration acceleration, and bus voltage; the control decision unit is used to determine whether the operating parameters meet the corresponding constraints; if the operating parameters meet the constraints, a first decision module in the control decision unit controls the pitch actuator to perform pitch operation through the SiC pitch drive unit; wherein the first decision module is used to implement the pitch operation through FPGA control.

[0015] The technical solution of this application has the following technical advantages over the prior art: In the pitch control method for wind turbines provided in this application, the operating parameters of the wind turbine are obtained through multiple hardware sensing devices (i.e., multiple redundant safety chains). When the FPGA determines that at least one parameter (i.e., any fault) meets the constraint conditions, it bypasses the software control layer and immediately controls the pitch actuator to perform pitch operation through the SIC pitch drive device. This ensures that emergency feathering can still be reliably executed under any single fault or software failure, greatly improving the safety of the pitch control system of the wind turbine. Attached Figure Description

[0016] The preferred embodiments of this application will be described in detail below with reference to the accompanying drawings, which will help to understand the purpose and advantages of this application, wherein: Figure 1 This is a schematic diagram of the structure of a pitch control system for a wind turbine provided in an embodiment of this application; Figure 2 This is a schematic diagram of a pitch control method for a wind turbine provided in an embodiment of this application; Figure 3 This is a schematic diagram of the structure of a triple-redundant hardware security chain provided in an embodiment of this application; Figure 4 A schematic diagram of the overdrive principle provided in the embodiments of this application; Figure 5 A schematic diagram of the wind energy utilization coefficient provided in the embodiments of this application; Figure 6 A timing diagram for generating feathering commands using APC provided in an embodiment of this application. Detailed Implementation

[0017] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0018] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0019] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0020] Furthermore, the technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0021] like Figure 1 The diagram shows a pitch control system for a wind turbine provided in an embodiment of this application. The pitch control system includes: various hardware sensors 11, a control decision device 12, a SiC pitch drive device 13, and a pitch actuator 14; wherein, Multiple hardware sensing devices 11 are used to acquire the operating parameters of the wind turbine; wherein, the operating parameters of the wind turbine include at least one of the following: rotor speed, tower vibration acceleration, and bus voltage; The control decision device 12 is used to determine whether the operating parameters meet the corresponding constraints. If the operating parameters meet the constraints, the first decision module 121 in the control decision device 12 controls the pitch actuator 14 to perform pitch operation through the SIC pitch drive device 13; wherein, the first decision module implements the pitch operation through FPGA control.

[0022] In some examples of this application, various hardware sensing devices 11 include at least one of the following: The first sensor is installed on the rear end of the wind turbine motor to collect the rotor speed; The second sensor is installed on the main shaft and gearbox of the wind turbine to collect the tower vibration acceleration. The third sensor is installed on the DC bus of the wind turbine to collect the bus voltage.

[0023] Here, a second sensor (e.g., a range ≥ 0.3g and a frequency response of 1–10 Hz) is installed on the main shaft and gearbox; a first sensor (e.g., a high-resolution absolute encoder) is installed at the rear end of the motor to obtain the impeller speed; a third sensor, current and temperature sensor, etc., are installed on the DC bus and IGBT heat sink, and can be installed as needed according to usage requirements.

[0024] The DC bus serves as the power transmission channel, and its condition directly affects the grid connection efficiency and stability of wind turbines; while the IGBT heat sink ensures the safety of core power devices through temperature monitoring. Together, they support the reliable operation of wind turbines.

[0025] The DC bus is a crucial component in wind turbines, connecting the generator to the grid-connected inverter. The alternating current (AC) generated by the generator is first converted to direct current (DC) by a rectifier, then transmitted via the DC bus to the inverter, and finally output to the power grid.

[0026] Here, the first, second, and third sensors are directly connected to the three independent I / O ports of the FPGA via three independent hardwired connections.

[0027] In some examples of this application, the pitch control system of the wind turbine also includes an energy device, which includes a power grid and a capacitor module, with the power grid serving as the main power source and the capacitor module serving as the backup power source; the first decision module 121 is used to disconnect the emergency feathering command EFC power source connected to the enable terminal of the SIC pitch drive device 13 if the bus voltage is less than a preset voltage threshold, and to establish a connection between the enable terminal and the capacitor module.

[0028] Alternatively, the FPGA output is connected to a power relay, which is used to cut off the enable (EFC) power supply to the SIC pitch drive 13. This path is a purely hardware circuit without any software processing.

[0029] EFC is an emergency feathering control signal triggered in the event of a safety chain failure. It is provided by the nacelle through the slip ring hub and is designed as a normally closed 24V energized circuit. When no safety chain failure occurs, the circuit is closed, meaning the safety chain EFC signal outputs a 24V high level. When a safety chain failure occurs, the circuit is open, meaning the safety chain EFC signal outputs a 0V low level. At this time, the feathering action is executed by the software layer.

[0030] In some examples of this application, the various hardware sensing devices 11 also include a lidar mounted on the top of the nacelle. If the operating parameters do not meet the constraints, the second decision module 122 in the control decision device 12 determines the optimal pitch angle based on the aerodynamic model of blade element momentum theory and the tip speed ratio. The tip speed ratio is determined by the wind speed and rotor speed collected by the lidar. The second decision module 122 is used to implement pitch operation through adaptive predictive control (APC). It also determines the pitch angle compensation amount based on the wind speed and the dynamic inverse controller. Based on the optimal pitch angle and the pitch angle compensation amount, a feathering command is generated. The feathering command is used to instruct the pitch actuator 14 to perform pitch operation through the SIC pitch drive device 13.

[0031] In some examples of this application, the control decision device 12 further includes a module for switching, such as a switching switch, which connects the first decision module 121 when the operating parameters meet the constraints, so that the first decision module 121 performs the pitch operation, and disconnects the connection with the second decision module 122, thereby isolating the interference of the second decision module to the first decision module.

[0032] In one example, an aerodynamic model based on blade element momentum theory (BEM) is built into the APC. Its feedforward control channel is configured to receive predicted wind speed from lidar and real-time impeller rotation speed from the encoder, and iteratively solves for the maximum wind energy utilization coefficient Cp and the corresponding optimal pitch angle under the current wind conditions in 0.1° steps within a range of -2° to 92°.

[0033] Configure the dynamic inverse controller parameters of the feedback control channel: Set the wind speed threshold. When the wind speed is less than the first wind speed threshold (e.g., 10 m / s), the proportional gain is reduced (e.g., reduced by 20%) to improve the energy capture efficiency at low wind speeds; when the wind speed is greater than the second wind speed threshold (e.g., 15 m / s), the proportional gain is increased (e.g., increased by 40%) to effectively suppress the integral saturation phenomenon caused by the back electromotive force.

[0034] The optimal pitch angle calculated by the feedforward is combined with the compensation amount generated by the feedback controller to finally generate the SVPWM (space vector pulse width modulation) waveform that drives the SiC power module.

[0035] In some examples of this application, the energy device also includes a management system (BMS): the BMS can be used to: determine the SOH value of the capacitor module; and determine a charging and discharging strategy for the capacitor module based on the SOH value.

[0036] In some examples of this application, the BMS determines the charging and discharging strategy for the capacitor module based on the SOH value, including: Determine whether the SOH value meets the corresponding threshold; If the SOH value is determined to meet the corresponding threshold, the maximum charging current value is set to the first current value; wherein the maximum charging current value is greater than the first current value.

[0037] In one example, an online capacitor health (SOH) assessment algorithm is enabled in the BMS. The system periodically (e.g., every 24 hours) calculates the capacitance value, equivalent internal resistance, and leakage current offset, and updates the SOH value in real time based on the coupling model.

[0038] In some examples of this application, the various hardware sensing devices 11 also include a temperature sensor disposed on the DC bus, and the BMS determines the charging and discharging strategy for the capacitor module based on the SOH value, and further includes: Determine whether the SOH value meets the corresponding threshold; if the SOH value meets the corresponding threshold, then set the maximum charging current value to the first current value; wherein the maximum charging current value is greater than the first current value; Determine whether the operating temperature of the capacitor module meets the corresponding temperature threshold; the operating temperature is obtained by a temperature sensor; if the operating temperature meets the corresponding temperature threshold, the capacitor module is charged using a preset pulse method.

[0039] The charging and discharging strategy is as follows: when the SOH value meets the corresponding threshold (e.g., SOH value < 80%), the maximum charging current is automatically limited to the first charging current (e.g., 0.5C); when the temperature sensor detects that the operating temperature of the capacitor module meets the corresponding threshold (e.g., operating temperature < -10℃), the pulse heating mode is automatically triggered (intermittent charging with a current of 10A and a pulse width of 50ms).

[0040] In some examples of this application, the pitch actuator 14 includes at least two permanent magnet synchronous motors and blades, with the at least two permanent magnet synchronous motors being connected by a backlash-free gear meshing.

[0041] Here, the permanent magnet synchronous motor is used for dual-drive synchronization: the gear backlash is eliminated through a backlash elimination control algorithm, which solves the stress concentration problem of traditional single-point drive.

[0042] The permanent magnet synchronous motor (PMSM) is connected to the pitch bearing of the propeller blades via a high-precision reduction gearbox. A dual-motor backlash-free drive layout is preferred, with the two motors working collaboratively through a backlash-free control algorithm to eliminate backlash in the gear transmission.

[0043] In some examples of this application, the various hardware sensing devices 11 also include a current sensor disposed on the DC bus, and the first decision module 121 and the second decision module 122 are further used to: determine the performance degradation coefficient of each of the at least two permanent magnet synchronous motors; wherein the performance degradation coefficient is determined based on the shaft current of each permanent magnet synchronous motor, the shaft current being acquired by the current sensor; determine a target permanent magnet synchronous motor from the at least two permanent magnet synchronous motors according to the performance degradation coefficient, and have the target permanent magnet synchronous motor perform pitch operation.

[0044] The embodiments of this application dynamically allocate pitch control tasks based on load spectrum analysis, alternating the motor running time under high / low stress conditions to extend bearing service life.

[0045] When allocating pitch control tasks, a pitch control task balancing algorithm is used. This algorithm records the running time of each blade under different wind speed ranges (corresponding to different mechanical loads) and dynamically adjusts the task allocation in the background to make the wear of the pitch actuator 14 more even.

[0046] It should be noted that a SiC (silicon carbide) pitch drive unit 13 is installed in the hub of each blade. This unit includes a high-voltage pitch drive cabinet, which can integrate a three-phase inverter power module based on SiC (silicon carbide) devices, an FPGA, a capacitor module and its management system (BMS); for example, the capacitor module and FPGA can be soldered into the high-voltage pitch drive cabinet using plug-in methods.

[0047] The pitch control system for wind turbines provided in this application can achieve the following significant effects: (1) The aerodynamic-electromechanical collaborative control algorithm can significantly improve the response speed of wind turbines to sudden changes in wind speed, reduce power fluctuations, and improve power generation efficiency compared with the PID in the existing technology. Moreover, the aerodynamic-electromechanical collaborative control algorithm shortens the pitch response time and reduces power fluctuations under turbulent conditions.

[0048] (2) By constructing a triple redundant hardware safety chain and hardware override execution mechanism independent of software, emergency feathering can still be reliably executed in the event of any single failure or software failure, which greatly improves safety.

[0049] (3) By evaluating the SOH value of the capacitor module and the performance degradation coefficient of the permanent magnet synchronous motor, the service life of components such as the capacitor module and gearbox can be improved, and the operation and maintenance costs can be reduced accordingly.

[0050] like Figure 2The illustration shows a pitch control method for a wind turbine provided in an embodiment of this application. This pitch control method is applied to the pitch control system of a wind turbine, which may include various hardware sensing devices, control decision devices, SiC pitch drive devices, and pitch execution devices. Figure 2 In China, the pitch control method for wind turbine units includes the following steps: Step 201: Obtain the operating parameters of the wind turbine through various hardware sensing devices; wherein, the operating parameters of the wind turbine include at least one of the following: rotor speed, tower vibration acceleration, and bus voltage; Step 203: Determine whether the operating parameters meet the corresponding constraints through the control decision-making device; Step 205: If the operating parameters meet the constraints, the first decision module in the control decision device controls the pitch actuator to perform the pitch operation through the SIC pitch drive device; wherein, the first decision module controls the pitch operation through FPGA (Field Programmable Gate Array).

[0051] The embodiments of this application provide a pitch control method for wind turbines. The method acquires the operating parameters of the wind turbine through multiple hardware sensing devices (i.e., multiple redundant safety chains). When the FPGA determines that at least one parameter (i.e., any fault) meets the constraint conditions, it bypasses the software control layer and immediately controls the pitch actuator to perform pitch operation through the SIC pitch drive device. This ensures that emergency feathering can still be reliably executed under any single fault or software failure, greatly improving the safety of the pitch control system of the wind turbine.

[0052] The following describes step 201 (i.e., acquiring the operating parameters of the wind turbine through various hardware sensing devices; wherein the operating parameters of the wind turbine include at least one of the following: rotor speed, tower vibration acceleration, and bus voltage) in detail.

[0053] In step 201, the operating parameters of the wind turbine are collected in real time or at a preset frequency using various hardware sensors deployed on the wind turbine. These operating parameters are key indicators for evaluating the performance of the wind turbine, optimizing power generation efficiency, and ensuring safe operation. Optionally, these operating parameters include the operating parameters of various components of the wind turbine during operation, such as the rotor speed, tower vibration acceleration, and bus voltage.

[0054] Following on from the previous text, the aforementioned redundant safety chains can include: a safety chain corresponding to the impeller speed, a safety chain corresponding to the tower vibration acceleration, and a safety chain corresponding to the bus voltage. It should be noted that these redundant safety chains can be set according to the fault type; for example, the safety chain corresponding to the bus voltage can be used to detect power outage faults.

[0055] In one example, the multiple hardware sensing devices include at least one of the following: a first sensor, a second sensor, and a third sensor; wherein the first sensor is installed on the rear end of the wind turbine motor for acquiring the rotor speed; the second sensor is installed on the main shaft and gearbox of the wind turbine for acquiring the tower vibration acceleration; and the third sensor is installed on the DC bus of the wind turbine for acquiring the bus voltage.

[0056] Here, even if the operating parameters collected by any of the first, second, and third sensors are faulty, pitch control can still be achieved through the FPGA.

[0057] The following is a detailed description of step 203 (i.e., determining whether the running parameters meet the corresponding constraints).

[0058] Before step 203, corresponding constraints are set for each operating parameter in advance. These constraints refer to the restrictive requirements that the wind turbine must meet during operation. The constraints can be quantified by thresholds. For example, a corresponding threshold is set for the rotor speed (such as a preset speed threshold), a corresponding threshold is set for the bus voltage (such as a preset voltage threshold), and a corresponding threshold is set for the tower vibration acceleration (such as a preset acceleration threshold).

[0059] When the operating parameters meet the corresponding constraints, a corresponding signal will be generated. For example, when the impeller speed exceeds the corresponding preset speed threshold (e.g., 20 rpm), S(Sensor)1 (i.e., impeller overspeed signal) will be generated; when the tower vibration acceleration exceeds the preset acceleration threshold (e.g., 0.3g), S2 (i.e., vibration exceeding standard signal) will be generated; when the bus voltage is lower than the corresponding preset voltage threshold (300 V DC), S3 (i.e., power grid failure signal) will be generated.

[0060] In one example, when determining whether the operating parameters meet the corresponding constraints, multi-dimensional parameter correlation can be used to more comprehensively reflect the operating status of the wind turbine and avoid the limitations of judging by a single parameter.

[0061] The hardware architecture of the triple-redundant hardware security chain is described in detail below.

[0062] exist Figure 3In this process, the FPGA is used to acquire the S1, S2, and S3 signals; the FPGA hardware voter obtains the voting output (as described below) based on the acquired signals. When any of the S1, S2, and S3 signals are acquired, the execution unit executes (such as the SIC pitch drive device driving the pitch actuator) to force the feathering action (i.e., to perform the pitch operation).

[0063]

[0064] If the tower vibration acceleration exceeds a preset acceleration threshold (e.g., 0.3g) and the vibration frequency is within a preset frequency range (e.g., 1–10 Hz), an S2 signal (i.e., vibration exceeding the limit) is generated; if the bus voltage is lower than the corresponding preset voltage threshold (300 V DC) and the duration of the voltage drop exceeds a preset duration threshold (e.g., 10 ms), an S3 signal (i.e., power grid failure) is generated. See the table below for details.

[0065] The following describes step 205 in detail (i.e., if the operating parameters meet the constraints, the first decision module in the control decision device controls the pitch actuator to perform the pitch operation through the SIC pitch drive device; wherein the first decision module implements the pitch operation through FPGA control).

[0066] In this step, when the operating parameters meet the constraints, the first decision module in the control decision device controls the pitch actuator to perform pitch operation through the SIC pitch drive device. The first decision module implements the pitch operation through FPGA control.

[0067] Optionally, the second decision module implements pitch control through adaptive predictive control (APC), while the first decision module implements pitch control through a field programmable gate array (FPGA).

[0068] Following the previous text, the first, second, and third sensors are used to collect the impeller speed, bus voltage, and tower vibration acceleration, respectively. Optionally, the first, second, and third sensors are connected to three independent I / O ports of the FPGA.

[0069] In one example, the first decision module also includes a switching element connected to the FPGA output. When the bus voltage meets the corresponding constraint conditions, this switching element is used to disconnect the enable (e.g., EFC) power supply to the SiC pitch drive. If the switching element is a power relay, the power relay is used to disconnect the enable (e.g., EFC) power supply to the SiC pitch drive. This path is a purely hardware circuit, and does not undergo any software layer processing when performing pitch operation. Thus, even if a software-level failure occurs, pitch operation can still be implemented through the FPGA.

[0070] The following example uses the bus voltage meeting the corresponding constraint conditions.

[0071] In one example, the pitch control system of the wind turbine also includes a capacitor module; if the bus voltage meets the corresponding constraint conditions, the enable power of the SIC pitch drive is cut off and switched to the capacitor module, which then provides power to the SIC pitch drive.

[0072] For example, if the third sensor detects that the bus voltage is less than 300 V DC and lasts for more than 10 ms, it immediately sends a "power outage" signal to the APC and FPGA.

[0073] The second decision module: APC generates a feathering command within ≤50 ms, and drives the motor to start feathering.

[0074] First decision module: The FPGA directly receives the hard-wired signal from S3. Due to the typhoon causing the impeller speed to spike instantly and exceed the 20 rpm threshold (S1 signal is also triggered), the hardware logic circuit in the FPGA immediately meets the voting conditions, drives the power relay within ≤5ms, the hardware override cuts off the enable power of the SIC pitch drive, and switches to the capacitor module to power the SIC pitch drive.

[0075] Here, hardware override (such as) Figure 4 As shown in the diagram, this refers to a mechanism that bypasses the software control layer and directly executes pitch control via the FPGA when any of the three redundant hardware security chains is triggered. Its principle is to implement a fully hardware-based path through the FPGA: "signal input → logic judgment by the overridden execution unit → execution output (i.e., cutting off the IGBT power supply and forcibly starting the feathering)," completely avoiding the risk of software crashes or delays.

[0076] Here, after a power grid failure, the system quickly switches to a power supply voltage (e.g., 600VDC high voltage) provided by the capacitor module to the frame control system of the wind turbine, driving the permanent magnet synchronous motor to rotate the blades to a safe feathering position of 92° at a maximum speed of 9° / s.

[0077] In this example, the entire process from the occurrence of the wind turbine failure to the completion of feathering took less than 11 seconds. The introduction of the hardware override mechanism ensured that even if the software of the second decision module might malfunction due to voltage disturbances, emergency feathering could still be reliably executed, successfully avoiding a major tower sweeping accident caused by speed runaway.

[0078] In some embodiments of this application, if the operating parameters do not meet the constraints, pitch control can be implemented through a second decision module, which employs adaptive predictive control (APC) to achieve pitch control. Optionally, this second decision module can achieve advanced and precise control by employing a feedforward-feedback composite control architecture, which deeply integrates aerodynamic models (e.g., aerodynamic models based on blade element momentum theory (BEM)) with electromechanical actuation.

[0079] In one example, the various hardware sensing devices also include a lidar mounted on the top of the nacelle, with its scanning surface located in front of the rotor, for real-time wind speed acquisition. The pitch control method of the wind turbine also includes: if the operating parameters do not meet the constraints, the second decision module determines the optimal pitch angle based on the aerodynamic model of the blade element momentum theory built into the APC and the tip speed ratio; and determines the compensation amount of the pitch angle based on the wind speed and the dynamic inverse controller; and generates a feathering command based on the optimal pitch angle and the compensation amount of the pitch angle. The feathering command is used to instruct the pitch actuator to perform pitch operation through the SIC pitch drive device.

[0080] In this example, in the feedforward channel, the optimal pitch angle is calculated using an aerodynamic model based on blade element momentum theory (BEM); then, in the feedback channel, a dynamic inverter controller (such as an anti-saturation dynamic inverter controller) is used to determine the compensation amount for the pitch angle; finally, a feathering command is generated based on the optimal pitch angle and the compensation amount for the pitch angle, which is used to instruct the pitch operation to be performed through the SIC pitch drive.

[0081] Here, the tip speed ratio is determined by the wind speed and impeller rotation speed collected by the lidar; alternatively, the tip speed ratio can be determined based on the impeller rotation speed, wind speed, and impeller radius.

[0082] For example, the feedforward channel calculates the optimal pitch angle in real time based on blade element momentum theory (BEM).

[0083] in: The tip speed ratio ( : Impeller rotational speed (rad / s), R: impeller radius (m), v: wind speed (m / s)); Wind energy utilization coefficient (e.g.) Figure 5 As shown in the figure, data is acquired in real time through lidar and strain sensors; .

[0084] It should be noted that wind energy utilization rate is a core indicator for evaluating the efficiency of wind turbines in converting wind energy into mechanical energy. It is defined as the ratio of the actual output power of the wind turbine to the theoretical power of wind energy within the swept area of ​​the rotor. The wind energy utilization coefficient can be calculated using the following formula:

[0085] in, ρ represents the mechanical power output of the wind turbine (measured by a strain sensor); ρ represents the air density (obtained in real time by temperature and pressure sensors). R is the impeller swept area (R is the impeller radius). The incoming wind speed (measured by lidar).

[0086] In determining the optimal pitch angle, a search is performed within θ. Maximum value (e.g., searching in 0.1° steps within the range of -2° to 92°) (maximum value), and Substituting the maximum value into the formula above to calculate the optimal pitch angle, we can iterate to obtain the global optimal solution (i.e., the optimal pitch angle).

[0087] In this example, the ability of lidar to predict wind speed changes in advance (e.g., 1 second) and compensate for aerodynamic delays is a key technology for improving the dynamic response performance of wind turbines and optimizing power control. This technology leverages lidar's "look-ahead" wind measurement capabilities to detect sudden wind speed changes in advance. Combined with an aerodynamic model to predict the aerodynamic response delay of the impeller, it adjusts control parameters (such as pitch angle and rotational speed) before the wind speed change reaches the impeller, achieving more precise power capture and load control.

[0088] Aerodynamic delay refers to the time difference between when a change in wind speed is detected by a sensor (such as a lidar on the top of the nacelle) and when it actually acts on the impeller, producing a change in torque.

[0089] In one example, the compensation amount for the pitch angle is determined based on the wind speed and the dynamic inverse controller, including: if the wind speed is less than a first wind speed threshold, determining the first parameter of the dynamic inverse controller and determining the compensation amount for the pitch angle corresponding to the first parameter. If the wind speed is greater than the second wind speed threshold, then the second parameter of the state inversion controller is determined, and the compensation amount of the pitch angle corresponding to the second parameter is determined; wherein, the first threshold is less than the second wind speed threshold.

[0090] The principle of pitch control achieved through adaptive predictive control (APC) is described in detail below.

[0091] A feedforward-feedback control mechanism is adopted to deeply integrate the aerodynamic model with electromechanical actuators (such as the SIC pitch drive). The first step, the feedforward channel: calculates the optimal pitch angle in real time based on blade element momentum theory (BEM).

[0092] in: The tip speed ratio ( : Impeller rotational speed (rad / s), R: impeller radius (m), v: wind speed (m / s)); Wind energy utilization coefficient, obtained in real time through lidar and strain sensors; .

[0093] The following process is involved in determining the optimal pitch angle: Iterative calculation: Search in 0.1° steps within the angle range of -2° to 92°. The maximum value ensures the globally optimal solution.

[0094] Specifically, an aerodynamic model based on blade element momentum theory (BEM) is built into the APC. Its feedforward control channel is configured to receive predicted wind speed from the lidar and real-time impeller rotation speed from the encoder, and iteratively solves for the maximum wind energy utilization coefficient under the current wind conditions in 0.1° steps within a range of -2° to 92°. And the corresponding optimal pitch angle.

[0095] Dynamic compensation: Combines LiDAR to predict wind speed changes in advance (e.g., 1 second in advance) to compensate for aerodynamic delay.

[0096] The second step is the feedback channel, which employs an anti-saturation dynamic inverse controller.

[0097] in, This is the anti-saturation tracking time constant.

[0098] When the wind speed is less than the first wind speed threshold (e.g., 10 m / s): reduce (like Reduce by 20% and improve wind energy capture efficiency; When the wind speed is greater than the second wind speed threshold (e.g., 15 m / s), increase (e.g., by 40%), to suppress integral saturation caused by back electromotive force.

[0099] The third step is to determine the feathering command based on the optimal pitch angle and compensation amount, referring to the following formula.

[0100]

[0101] The following is combined with Figure 6 The process of APC implementing pitch control is described.

[0102] The first step is to use lidar to monitor wind speed in real time. (e.g., wind speed monitored at a sampling rate of 100Hz); The second step is to send a computation request to APC; The third step is to use the BEM aerodynamic model to calculate the current operating conditions. The optimal pitch angle corresponding to the maximum value ; The fourth step is to generate based on the dynamic inverse controller. (i.e., the amount of compensation for the pitch angle). The fifth step is to determine the feathering command based on the optimal pitch angle and compensation amount; In one example, an SVPWM (Space Vector Pulse Width Modulation) waveform is generated to drive the SIC pitch drive based on the optimal pitch angle and compensation amount. This waveform is used to perform pitch operation.

[0103] Step 6: The SIC pitch drive unit drives the permanent magnet synchronous motor to perform pitch operation.

[0104] Compared with the PID software control algorithm in the prior art, the feedforward-feedback control mechanism adopted in this application can improve the response speed and reduce power fluctuations under turbulent conditions.

[0105] exist Figure 6 The process also includes feeding back the safe sequence position after the pitch control operation to the APC, which then performs closed-loop correction on the dynamic controller based on the safe feather position to ensure the accuracy of the dynamic controller. This, in turn, can shorten the pitch response time and reduce power fluctuations during wind speed steps.

[0106] In some examples of this application, the pitch control method for the wind turbine further includes the following after switching the power supply voltage provided by the capacitor module: Determine the SOH value of the capacitor module; determine the charging and discharging strategy for the capacitor module based on the SOH value.

[0107] In embodiments of this application, online health management and optimization control are performed on the capacitor module to extend its service life.

[0108] In one example, the State of Harmony (SOH) of the capacitor module is evaluated online:

[0109] in, Actual capacitance value; Nominal capacitance value; Equivalent series internal resistance; Actual capacitance value; Leakage voltage offset.

[0110] In one example, the charging and discharging strategy for the capacitor module is determined based on the SOH value, including: Determine whether the SOH value meets the corresponding threshold; if the SOH value meets the corresponding threshold, then set the maximum charging current value to the first current value; wherein the maximum charging current value is greater than the first current value.

[0111] In one example, the various hardware sensing devices also include a temperature sensor located on the DC bus, which determines the charging and discharging strategy for the capacitor module based on the SOH value, and further includes: Determine whether the SOH value meets the corresponding threshold; if the SOH value meets the corresponding threshold, set the maximum charging current value to the first current value; wherein the maximum charging current value is greater than the first current value; determine whether the operating temperature of the capacitor module meets the corresponding temperature threshold; wherein the operating temperature is acquired by a temperature sensor; if the operating temperature meets the corresponding temperature threshold, charge the capacitor module using a preset pulse method.

[0112] The following example illustrates how to charge a capacitor module using a charge / discharge strategy corresponding to the SOH value: When the SOH value meets the corresponding threshold (e.g., SOH value < 80%), the capacitor module is charged using the first current value (e.g., charging current is 0.5C); when the operating temperature of the capacitor module meets the corresponding temperature threshold (e.g., temperature < -10℃), the preset pulse mode (e.g., current 10A, pulse width 50 ms) is triggered to charge the charging module.

[0113] In this example, the charge and discharge strategy was adjusted in real time by evaluating the SOH value of the capacitor module, thereby improving the cycle life of the capacitor module.

[0114] In some examples of this application, the performance degradation factor of power devices (such as SiC pitch drive devices) is evaluated, specifically: Various hardware sensing devices also include current sensors mounted on the DC bus, and the methods also include: Determine the performance degradation coefficient for each of at least two permanent magnet synchronous motors; wherein the performance degradation coefficient is determined based on the shaft current of each permanent magnet synchronous motor, which is acquired by a current sensor; The target permanent magnet synchronous motor is determined from at least two permanent magnet synchronous motors based on the performance degradation coefficient, and the pitch operation is performed by the target permanent magnet synchronous motor.

[0115] Alternatively, the performance degradation coefficient (i.e., ε) of the permanent magnet synchronous motor can be determined by the following formula: Warning conditions:

[0116] in, These are the direct-axis and quadrature-axis components of the shaft current, respectively. denoted as eccentric change rate.

[0117] Here, the performance degradation coefficient can be used to characterize the degree of current imbalance caused by internal aging of the permanent magnet synchronous motor, providing data for dynamically allocating pitch control tasks. The higher the ε, the more severe the current unhealthy condition of the permanent magnet synchronous motor. Δε / Δt is the amount of increase in the ε value per unit time, i.e., the rate of health degradation. When Δε / Δt > 0.01 / h, it indicates that the capacitor module has entered the inflection point of "accelerated failure" from "slow aging".

[0118] In the embodiments of this application, the load spectrum-driven task rotation algorithm can reduce the running time of a single motor under high / low stress conditions by switching the motor running time under high stress conditions, thereby reducing the wear rate of gearboxes, bearings, etc., and improving the service life of gearboxes and bearings.

[0119] In this embodiment, the APC records the running time of each blade under different wind speed ranges (corresponding to different mechanical loads) and adjusts the task allocation according to the running time, so that the wear of the pitch operation tends to be balanced.

[0120] Optionally, in this example, the pitch actuator includes at least two permanent magnet synchronous motors and blades, with the at least two permanent magnet synchronous motors connected by a backlash-free gear meshing.

[0121] Dual-drive synchronous permanent magnet synchronous motor: The backlash is eliminated by a backlash-eliminating control algorithm, which solves the stress concentration problem of traditional single-point drive.

[0122] For example, a permanent magnet synchronous motor (PMSM) is connected to the pitch bearing of the propeller blade via a high-precision reduction gearbox. A preferred approach is a dual-motor backlash-eliminating drive layout, where the two motors work together through a pre-defined backlash-eliminating control algorithm to eliminate backlash in the gear transmission.

[0123] The core of the backlash elimination control algorithm lies in applying a bias torque to eliminate backlash in the transmission system by controlling the coordinated operation of two or more motors. This bias torque can be achieved by applying a bias current, that is, adding an additional current as an auxiliary input to the original current loop main input.

[0124] The following describes a pitch control method for a wind turbine provided in this application embodiment, using different application scenarios: Application scenario: A typhoon hit an offshore wind farm, causing a momentary voltage drop (loss of voltage) in the power grid.

[0125] In this application scenario, the pitch control method for wind turbines may include the following process: (1) The third sensor (S3) detects that the bus voltage is <300 VDC and lasts for more than 10 ms, and immediately sends a "power grid failure" signal (i.e., S3 signal) to the APC and FPGA.

[0126] (2) Software layer response: APC controls the pitch actuator to perform pitch operation through the SIC pitch drive device.

[0127] (3) Hardware layer response: The FPGA directly receives the hard-wired signal of S3. Due to the typhoon, the speed of the impeller spikes instantly and exceeds the 20 rpm threshold (the S1 signal is also triggered). The hardware logic circuit in the FPGA meets the voting conditions, drives the relay, the hardware overrides and cuts off the EFC power supply of the driver, and forces the control to be transferred to the capacitor module power supply circuit.

[0128] Here, this application implements pitch control via FPGA, and performs protection independently of the software layer, such as overspeed protection (e.g., forcibly cutting off EFC when the impeller speed is >20 rpm).

[0129] The FPGA output directly controls the power relay, which is responsible for cutting off the enable (EFC) power supply to the SiC pitch drive. This path is a purely hardware circuit without any software processing.

[0130] (4) The capacitor module switches quickly (within 0.2 seconds) after the power grid fails, providing high voltage (e.g., 600VDC) to drive the permanent magnet synchronous motor to rotate the blades to a safe feathering position (e.g., rotating the blades to a safe feathering position of 92° at a maximum speed of 9° / s).

[0131] This application achieves a response time (e.g., less than 11 seconds) between the occurrence of a fault and the completion of feathering using an FPGA, which is shorter than that of an APC (e.g., the APC generates a feathering command within ≤50 ms, driving the motor to begin feathering). During the FPGA's pitch control operation, the introduction of a hardware override mechanism ensures reliable emergency feathering even in the event of software anomalies due to voltage disturbances, successfully preventing major tower sweeping accidents caused by speed control failure.

[0132] Application scenario: High-altitude wind fields, with large temperature differences between day and night and drastic wind speed fluctuations, pose a great challenge to the lifespan of equipment.

[0133] In application scenarios, the pitch control method for wind turbines provided in this application embodiment may include the following process: (1) Operation optimization based on load spectrum: Based on historical data, it was identified that daytime wind speeds are generally high (e.g., wind speed > 15 m / s). Therefore, a daytime strategy was set in the BMS: the pitch speed was set to the speed corresponding to the daytime strategy (e.g., limited to ≤ 7° / s). This operation can significantly reduce the impact stress of pitch action on gearbox and bearings under high aerodynamic loads.

[0134] (2) Charge and discharge management: Set corresponding charge and discharge strategies according to the wind speed characteristics during the day and night; for example, at night, the wind speed is low and the ambient temperature is low. At this time, the "capacitor maintenance mode" is triggered: the equalization charging strategy is executed and the pulse heating function is intermittently enabled to keep the working temperature of the capacitor module above the optimal working range.

[0135] This application improves the SOH value of the capacitor module by periodically statistically analyzing the characteristics of wind speed during the day and night, and reduces unplanned downtime caused by pitch failure, thereby reducing overall operation and maintenance costs and achieving the goal of extending equipment life and reducing operating costs.

[0136] It should be noted that both APC and FPGA participate in pitch control. Since FPGA directly acquires the operating parameters collected by the first, second and third sensors, it can respond to faults more quickly; and when there are software faults, it completely avoids the risk of software crashes or delays.

[0137] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this application.

Claims

1. A pitch control method for a wind turbine generator, characterized in that, A pitch control system for wind turbine generators, the system comprising: various hardware sensors, a control decision-making device, a SiC pitch drive device, and a pitch actuator, the method comprising: The operating parameters of the wind turbine are obtained through a variety of hardware sensing devices; wherein, the operating parameters of the wind turbine include at least one of the following: rotor speed, tower vibration acceleration, and bus voltage; The control decision-making device determines whether the operating parameters meet the corresponding constraints. If the operating parameters meet the constraints, the first decision module in the control decision device controls the pitch actuator to perform pitch operation through the SIC pitch drive device; wherein, the first decision module implements the pitch operation through FPGA control.

2. The pitch control method for wind turbine generators according to claim 1, characterized in that, The plurality of hardware sensing devices includes at least one of the following: The first sensor is installed on the rear end of the motor of the wind turbine and is used to collect the rotational speed of the impeller; The second sensor is installed on the main shaft and gearbox of the wind turbine to collect tower vibration acceleration. The third sensor is installed on the DC bus of the wind turbine to collect the bus voltage.

3. The pitch control method for wind turbines according to claim 1 or 2, characterized in that, The pitch control system of the wind turbine also includes a capacitor module, and the method further includes: If the bus voltage is less than a preset voltage threshold, the emergency feathering command (EFC) power supply connected to the enable terminal of the SIC pitch drive device is disconnected, and a connection is established between the enable terminal and the capacitor module.

4. The pitch control method for wind turbine generators according to claim 1 or 2, characterized in that, The various hardware sensing devices also include a lidar mounted on the top of the cabin, and the method further includes: If the operating parameters do not meet the constraints, the second decision module in the control decision device determines the optimal pitch angle based on the aerodynamic model of blade element momentum theory and the tip speed ratio; wherein, the tip speed ratio is determined by the wind speed and rotor speed collected by the lidar, and the second decision module is used to achieve pitch control through adaptive predictive control (APC); and The compensation amount for the pitch angle is determined based on the wind speed and the dynamic reverse controller. Based on the optimal pitch angle and the pitch angle compensation amount, a feathering command is generated. The feathering command is used to instruct the pitch actuator to perform pitch operation through the SIC pitch drive device.

5. The pitch control method for wind turbines according to claim 3, characterized in that, The method further includes: Determine the SOH value of the capacitor module; The charging and discharging strategy for the capacitor module is determined based on the SOH value.

6. The pitch control method for wind turbine generators according to claim 5, characterized in that, The step of determining the charging and discharging strategy for the capacitor module based on the SOH value includes: Determine whether the SOH value meets the corresponding threshold; If the SOH value is determined to meet the corresponding threshold, the maximum charging current value is set as the first current value; wherein the maximum charging current value is greater than the first current value.

7. The pitch control method for wind turbine generators according to claim 5, characterized in that, The various hardware sensing devices also include a temperature sensor mounted on the DC bus, and the step of determining the charging and discharging strategy for the capacitor module based on the SOH value further includes: Determine whether the SOH value meets the corresponding threshold; If the SOH value is determined to meet the corresponding threshold, the maximum charging current value is set as the first current value; wherein the maximum charging current value is greater than the first current value. Determine whether the operating temperature of the capacitor module meets the corresponding temperature threshold; wherein, the operating temperature is acquired by the temperature sensor; If the operating temperature is determined to meet the corresponding temperature threshold, the capacitor module is charged using a preset pulse method.

8. The pitch control method for wind turbine generators according to claim 1 or 2, characterized in that, The pitch actuator includes at least two permanent magnet synchronous motors and blades, with the at least two permanent magnet synchronous motors connected by a backlash-free gear meshing.

9. The pitch control method for a wind turbine generator according to claim 8, characterized in that, The various hardware sensing devices also include a current sensor disposed on the DC bus, and the method further includes: A performance degradation coefficient is determined for each of at least two permanent magnet synchronous motors; wherein the performance degradation coefficient is determined based on the shaft current of each permanent magnet synchronous motor, the shaft current being acquired by the current sensor; A target permanent magnet synchronous motor is determined from at least two permanent magnet synchronous motors based on the performance degradation coefficient, and the pitch operation is performed by the target permanent magnet synchronous motor.

10. A pitch control system for a wind turbine generator, characterized in that, include: It includes various hardware sensors, control and decision-making devices, SiC pitch drive devices, and pitch actuators; among them... The various hardware sensing devices are used to acquire the operating parameters of the wind turbine; wherein, the operating parameters of the wind turbine include at least one of the following: rotor speed, tower vibration acceleration, and bus voltage; The control decision device is used to determine whether the operating parameters meet the corresponding constraints. If the operating parameters meet the constraints, the first decision module in the control decision device controls the pitch actuator to perform pitch operation through the SIC pitch drive device; wherein, the first decision module is used to implement the pitch operation through FPGA control.

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