Adaptive Control Method and System for Wind Turbine Generators During Low Voltage Ride

Abstract

This invention discloses an adaptive control method and system for wind turbine generators during low-voltage ride-through (LVRT). The method includes the following steps: S1, real-time acquisition of wind turbine generator operating data, including generator speed and a LVRT flag; S2, determination of whether the LVRT flag is true; if true, switching the generator control system from conventional power generation control mode to LVRT control mode; otherwise, maintaining the generator in conventional power generation control mode; in LVRT control mode, parallel execution of drivetrain resistance adaptive control, pitch response adaptive control, and advance pitch adaptive control; S3, comprehensive control of the generator based on the final resistance torque, the superimposed pitch rate, and the adaptive advance pitch value. This invention can reduce generator power fluctuations during LVRT while ensuring blade clearance and load safety, thereby improving generator operational stability and safety.

Description

Technical Field

[0001] This invention relates to the field of wind power generation technology, specifically to an adaptive control method and system for wind turbine generator sets during low voltage ride-through. Background Technology

[0002] As the capacity of individual wind turbine generators increases, the fluctuations in active power output during low-voltage ride-through (LVRT) processes become more pronounced. This makes the generators highly susceptible to grid disconnection and other malfunctions during LVRTs. Furthermore, excessive power fluctuations can lead to excessively high ultimate loads on major components such as blades, hubs, and towers, impacting the generator's operational stability and safety. Therefore, reducing power fluctuations during LVRTs, improving grid disconnection rates, and enhancing operational stability and safety will be a significant challenge for the design of the overall control system.

[0003] The magnitude of power fluctuations during low-voltage ride-through of wind turbine generators is closely related to their operational stability and grid adaptability. Currently, the following solutions are mainly adopted:

[0004] 1. Before each test, the closed-loop power generation parameters and monitoring control parameters of the control system are adjusted to reduce power fluctuations and improve the low voltage ride-through success rate. Although this method can improve the low voltage ride-through success rate and reduce the grid disconnection rate to a certain extent, it requires corresponding adjustments before each low voltage ride-through test, which is cumbersome and not very universal.

[0005] 2. By reducing the advance pitch adjustment, the wind energy capture of the unit during the low-voltage ride-through process can be increased, thereby reducing power fluctuations and improving the unit's grid connection rate during the low-voltage ride-through process. Although this approach can reduce the unit's power fluctuations during the test to some extent, reducing the advance pitch adjustment requires consideration of blade clearance issues and load verification, which involves a large workload and poses safety risks. Summary of the Invention

[0006] To address the technical problems existing in the prior art, the present invention provides an adaptive control method and system for wind turbine generators during low voltage ride-through (LVRT) to reduce power fluctuations during LVRT.

[0007] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows:

[0008] An adaptive control method for wind turbine generators during low voltage ride-through includes the following steps:

[0009] S1. Real-time acquisition of wind turbine generator set operation data, including generator speed and low voltage ride-through flag;

[0010] S2. Determine if the low voltage ride-through process flag is true; if true, switch the unit control system from the conventional power generation control mode to the low voltage ride-through control mode; otherwise, maintain the unit in the conventional power generation control mode; in the low voltage ride-through control mode, execute the drive train resistance adaptive control, pitch response adaptive control, and advance pitch adaptive control in parallel.

[0011] The adaptive control of the transmission chain resistance includes: obtaining the transmission chain resistance limiting coefficient based on the time of the low voltage crossover flag activation using a lookup table method, and then multiplying the resistance torque output by the resistance device by the transmission chain resistance limiting coefficient to obtain the final resistance torque, thereby realizing the dynamic adjustment of the resistance torque.

[0012] The pitch response adaptive control includes: calculating the current generator rotational acceleration GenAcc based on the generator speed; if GenAcc is greater than a preset threshold GenAcc1, then a preset pitch rate Pitchrate1 is superimposed on the pitch rate Pitchrate output by the unified pitch PID controller to obtain the superimposed pitch rate.

[0013] The adaptive advance pitch control includes: first, estimating the wind speed to obtain the estimated wind speed, and then obtaining the adaptive advance pitch value based on the estimated wind speed.

[0014] S3. Based on the final applied torque, superimposed pitch rate, and adaptive advance pitch value obtained in S2, perform integrated control of the unit to suppress power fluctuations and ensure unit safety.

[0015] Preferably, in the adaptive control of the transmission chain resistance in step S2, a two-dimensional interpolation table of activation time and transmission chain resistance limiting coefficient is preset, wherein the two-dimensional interpolation table of activation time and transmission chain resistance limiting coefficient has a preset mapping relationship between activation time and transmission chain resistance limiting coefficient; by querying the two-dimensional interpolation table of activation time and transmission chain resistance limiting coefficient, the transmission chain resistance limiting coefficient corresponding to the activation time can be obtained; wherein the activation time is the time counted after the low voltage crossover flag is activated.

[0016] Preferably, in the advance pitch adaptive control in step S2, the formula for estimating the wind speed v is:

[0017]

[0018] Where P is power, ρ is air density, A is wind turbine area, and Cp is power coefficient.

[0019] Preferably, in the advance pitch adaptive control in step S2, a two-dimensional interpolation table of estimated wind speed and advance pitch value is preset; wherein the two-dimensional interpolation table of estimated wind speed and advance pitch value has a preset mapping relationship between estimated wind speed and advance pitch value; by querying the two-dimensional interpolation table of estimated wind speed and advance pitch value, the advance pitch value corresponding to the estimated wind speed can be obtained.

[0020] Preferably, in step S1, after acquiring the running data, the running data is cleaned and filtered.

[0021] Preferably, the preset pitch rate Pitchrate1 is in the range of 1-3 deg / s.

[0022] The present invention also discloses an adaptive control system for a wind turbine generator during low voltage ride-through, comprising an interconnected memory and a processor, wherein the memory stores a computer program, and the computer program executes the steps of the method described above when run by the processor.

[0023] Compared with the prior art, the advantages of the present invention are as follows:

[0024] The adaptive control of the drive train resistance in this invention obtains the drive train resistance limiting coefficient by querying a two-dimensional interpolation table of activation time and drive train resistance limiting coefficient. This dynamically dampens the torsional oscillation of the drive train, effectively suppressing overshoot and oscillation of power and speed, allowing the power curve to transition smoothly during voltage recovery and avoiding protective grid disconnection triggered by severe fluctuations. This adaptive control of the drive train resistance is specifically developed for low-voltage ride-through conditions. Conventional normal power generation control only sets a fixed limiting value for the drive train resistance torque and does not employ time-based adaptive control.

[0025] The pitch response adaptive control of this invention, by introducing generator rotational acceleration feedforward (superimposed with Pitchrate1), responds to the overspeed trend of the unit in advance. Currently, traditional PID control suffers from lag, while this method provides additional pitch rate in the early stages of rapid speed increase, capturing wind energy more quickly and suppressing speed spikes, thereby reducing the amplitude of power fluctuations at the source. The pitch response adaptive control logic of this invention differs from conventional gust control. Conventional gust control uses a two-dimensional interpolation table of "generator rotational acceleration - pitch angle" to determine whether to superimpose the preset pitch rate Pitchrate1, while the pitch response adaptive control logic developed for low-voltage ride-through conditions in this invention uses a single variable, "generator rotational acceleration," to determine whether to superimpose the preset pitch rate Pitchrate1, which can more quickly improve the pitch response speed during low-voltage ride-through.

[0026] The adaptive pitch control proposed in this invention obtains the optimal pitch advance value in real time by estimating wind speed and looking up a table. This provides a dynamic, safe aerodynamic pre-bending force, effectively suppressing blade deformation and tower sway, and directly controlling the ultimate load within a safe range. The adaptive pitch advance control proposed in this invention uses estimated wind speed as input and can dynamically adjust the pitch advance while ensuring blade clearance and load safety. It adaptively adjusts the pitch advance based on external conditions such as wind conditions, improving the power stability of the unit during low-voltage ride-through. In contrast, the pitch advance control in conventional normal power generation control uses power as input and a fixed "power-pitch angle" interpolation table to determine the output result, which is independent of current wind speed and other external operating conditions, resulting in poor adaptive capability.

[0027] The entire solution of this invention is based entirely on the existing standard sensors and controllers of the unit, eliminating the cost of adding additional sensors (such as radar) or actuators. Attached Figure Description

[0028] Figure 1 This is a flowchart of an embodiment of the adaptive control method for wind turbine generators during low voltage ride-through according to the present invention.

[0029] Figure 2 This is a control block diagram of the low voltage ride-through control mode of the present invention in an embodiment.

[0030] Figure 3 The flowchart shows an embodiment of the adaptive control of the transmission chain resistance in this invention.

[0031] Figure 4 The flowchart is for an embodiment of the pitch response adaptive control in this invention.

[0032] Figure 5 This is a flowchart of an embodiment of the advance pitch adaptive control in this invention.

[0033] Figure 6 This is a comparison chart of the power curves before and after the low-voltage ride-through optimization of the present invention. Detailed Implementation

[0034] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0035] like Figure 1 As shown in the embodiment of the present invention, the adaptive control method for wind turbine generators during low voltage ride-through includes the following steps:

[0036] S1. During the normal operation of the wind turbine generator set, collect wind speed, generator speed, generator power, and low voltage ride-through process flags, and perform data cleaning and filtering to ensure data reliability and eliminate signal interference.

[0037] S2. Determine whether the low voltage ride-through process flag bit processed in S1 is true. When the low voltage ride-through flag bit is detected to be true, the wind turbine generator control system will be automatically switched from the conventional power generation control mode to the low voltage ride-through control mode. If the low voltage ride-through flag bit is false, the generator control mode will continue to maintain the conventional power generation control mode.

[0038] In the low voltage ride-through control mode, the drive train resistance adaptive control, pitch response adaptive control and advance pitch adaptive control are executed in parallel.

[0039] The adaptive control of the drive chain resistance is as follows: Based on the time when the low voltage crossover flag is activated, the two-dimensional interpolation table of the pre-set activation time and drive chain resistance limiting coefficient is consulted to obtain the drive chain resistance limiting coefficient. Then, the resistance torque output by the resistance device is multiplied by the drive chain resistance limiting coefficient to obtain the final resistance torque, thereby realizing the dynamic adjustment of the resistance torque.

[0040] The pitch response adaptive control is as follows: The pitch control system obtains the generator rotational acceleration GenAcc by detecting the current generator speed. If the current generator rotational acceleration GenAcc > GenAcc1 (the threshold GenAcc1 is determined by the load results and operating data), the preset pitch rate Pitchrate1 is superimposed on the pitch rate Pitchrate output by the unified pitch PID to obtain the superimposed pitch rate, so as to suppress the unit overspeed.

[0041] The adaptive pitch control for advance pitch is as follows: the estimated wind speed v is calculated based on the current power of the unit, the rotor area, the air density and the power coefficient. Then, the estimated wind speed v is used to look up a table (two-dimensional interpolation table of estimated wind speed and advance pitch value) to obtain the adaptive advance pitch value.

[0042] S3. Based on the transmission chain resistance limiting value obtained in S2, the superimposed pitch rate, and the adaptive advance pitch value, perform comprehensive control of the unit to suppress power fluctuations and ensure unit safety.

[0043] The adaptive control method for wind turbine generators during low-voltage ride-through of the present invention can reduce the power fluctuation of the generator during low-voltage ride-through while ensuring blade clearance and load safety, improve the pass rate of low-voltage ride-through tests, reduce the ultimate load of large components such as blades, hubs, and towers during low-voltage ride-through, and improve the operational stability and safety of the generator during low-voltage ride-through.

[0044] The adaptive control of the drive train resistance in this invention obtains the drive train resistance limiting coefficient by querying a two-dimensional interpolation table of activation time and drive train resistance limiting coefficient. This dynamically dampens the torsional oscillation of the drive train, effectively suppressing overshoot and oscillation of power and speed, allowing the power curve to transition smoothly during voltage recovery and avoiding protective grid disconnection triggered by severe fluctuations. This adaptive control of the drive train resistance is specifically developed for low-voltage ride-through conditions. Conventional normal power generation control only sets a fixed limiting value for the drive train resistance torque and does not employ time-based adaptive control.

[0045] The pitch response adaptive control of this invention, by introducing generator rotational acceleration feedforward (superimposed with Pitchrate1), responds to the overspeed trend of the unit in advance. Currently, traditional PID control suffers from lag, while this method provides additional pitch rate in the early stages of rapid speed increase, capturing wind energy more quickly and suppressing speed spikes, thereby reducing the amplitude of power fluctuations at the source. The pitch response adaptive control logic of this invention differs from conventional gust control. Conventional gust control uses a two-dimensional interpolation table of "generator rotational acceleration - pitch angle" to determine whether to superimpose the preset pitch rate Pitchrate1, while the pitch response adaptive control logic developed for low-voltage ride-through conditions in this invention uses a single variable, "generator rotational acceleration," to determine whether to superimpose the preset pitch rate Pitchrate1, which can more quickly improve the pitch response speed during low-voltage ride-through.

[0046] The adaptive pitch control proposed in this invention obtains the optimal pitch advance value in real time by estimating wind speed and looking up a table. This provides a dynamic, safe aerodynamic pre-bending force, effectively suppressing blade deformation and tower sway, and directly controlling the ultimate load within a safe range. The adaptive pitch advance control proposed in this invention uses estimated wind speed as input and can dynamically adjust the pitch advance while ensuring blade clearance and load safety. It adaptively adjusts the pitch advance based on external conditions such as wind conditions, improving the power stability of the unit during low-voltage ride-through. In contrast, the pitch advance control in conventional normal power generation control uses power as input and a fixed "power-pitch angle" interpolation table to determine the output result, which is independent of current wind speed and other external operating conditions, resulting in poor adaptive capability.

[0047] The entire solution of this invention is based entirely on the existing standard sensors and controllers of the unit, eliminating the cost of adding additional sensors (such as radar) or actuators.

[0048] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0049] like Figure 1As shown in the embodiment of the present invention, the adaptive control method for wind turbine generators during low voltage ride-through includes the following steps:

[0050] S1. During unit operation, collect variables such as generator speed and low voltage ride-through flag, and perform data cleaning and filtering.

[0051] S2. Determine if the low-voltage ride-through process flag bit processed in S1 is true. When the low-voltage ride-through flag bit is detected as true, the wind turbine generator control system automatically switches from the conventional power generation control mode to the low-voltage ride-through control mode. If the low-voltage ride-through flag bit is false, the generator control mode remains the conventional power generation control mode. Figure 1 As shown;

[0052] like Figure 2 As shown, when the unit control system switches to the low voltage ride-through control mode, it simultaneously performs drive train resistance adaptive control, pitch response adaptive control, and advance pitch adaptive control; of course, in other embodiments, one or two control modes can be selected according to the actual situation.

[0053] like Figure 3 As shown, the adaptive control process of the drive train resistance is as follows: Based on the time when the low voltage crossover flag is activated, the pre-set two-dimensional interpolation table of activation time and drive train resistance limiting coefficient is consulted to obtain the drive train resistance limiting coefficient. Then, the resistance torque output by the resistance device is multiplied by the drive train resistance limiting coefficient to obtain the final resistance torque, thereby realizing the dynamic adjustment of the resistance torque.

[0054] The activation time-transmission chain resistance limiting coefficient two-dimensional interpolation table is preset, as shown in Table 1; where activation time refers to the time when the low voltage crossover flag is activated and the resistance limiting coefficient is the coefficient multiplied by the final resistance torque output by the resistance device, used to dynamically adjust the resistance torque magnitude, and this coefficient has no unit.

[0055] Table 1. Two-dimensional interpolation table of activation time-transmission chain resistance limiting coefficient

[0056]

[0057] like Figure 4 As shown, the specific process of pitch response adaptive control is as follows:

[0058] The generator rotational acceleration GenAcc is obtained by detecting the current generator speed. If the current generator rotational acceleration GenAcc > GenAcc1 (the threshold GenAcc1 is preset), then a pitch rate Pitchrate1 (preset to 2deg / s) is added to the pitch rate Pitchrate of the unified pitch PID output to suppress unit overspeed; otherwise, the pitch output maintains the unified pitch rate of the PID.

[0059] like Figure 5 As shown, the specific process of advance pitch adaptive control is as follows:

[0060] The estimated wind speed v is calculated based on the unit's current power, rotor area, air density, and power coefficient. The specific estimation formula is as follows:

[0061]

[0062] Where P is power, ρ is air density, A is wind turbine area, and Cp is power coefficient.

[0063] Based on the estimated wind speed, the adaptive advance pitch value is obtained by querying the two-dimensional interpolation table of estimated wind speed - advance pitch value; the form of the two-dimensional interpolation table of estimated wind speed - advance pitch value is shown in Table 2:

[0064] Table 2 Two-dimensional interpolation table for estimated wind speed and advance pitch control

[0065]

[0066] S3. Based on the transmission chain resistance limiting value obtained in S2, the superimposed pitch rate, and the adaptive advance pitch value, perform comprehensive control of the unit to suppress power fluctuations and ensure unit safety.

[0067] like Figure 6 The image shows a simulation comparison of the power curves before and after low-voltage ride-through optimization. The black curve represents the power curve before optimization, and the red curve represents the power curve after optimization. Figure 6 It can be concluded that after optimization using the adaptive algorithm, the power fluctuation after low voltage ride-through is smaller, and the power does not drop, which verifies the optimization effect of the adaptive method of the present invention on low voltage ride-through conditions.

[0068] This invention controls the generator based on real-time measurements of generator speed and power, ensuring that the unit can adjust in real time according to the current operating conditions and ensuring safe operation. This invention can ensure that the ultimate load of the wind turbine blades and hub does not increase; reduce the power fluctuation of the wind turbine during low voltage ride-through and improve the grid disconnection rate during transient processes; the algorithm has strong versatility and can be quickly expanded and ported according to different unit operating conditions.

[0069] This invention also discloses an adaptive control system for a wind turbine generator during low-voltage ride-through, comprising an interconnected memory and a processor. The memory stores a computer program, which, when run by the processor, executes the steps of the method described above. The control system of this invention corresponds to the control method described above and also possesses the advantages described therein.

[0070] The present invention can implement all or part of the processes in the methods of the above embodiments, or it can be implemented by hardware related to computer program instructions. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by a processor, it can implement the steps of the above method embodiments. The computer program includes computer program code, which can be in the form of source code, object code, executable file, or some intermediate form. The computer-readable storage medium includes: any entity or device capable of carrying computer program code, recording media, USB flash drive, portable hard drive, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc. The memory is used to store computer programs and / or modules. The processor implements various functions by running or executing the computer programs and / or modules stored in the memory, and by calling data stored in the memory. The memory may include high-speed random access memory, as well as non-volatile memory, such as hard disks, RAM, plug-in hard disks, smart media cards (SMC), secure digital (SD) cards, flash cards, at least one disk storage device, flash memory device, or other volatile solid-state storage devices.

[0071] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A method for adaptive control of a wind turbine during low voltage ride through, characterized in that, The method comprises the steps of: S1, collecting operation data of the wind turbine generator set in real time, the operation data comprising generator speed and low voltage ride through process flag; S2, judging whether the low voltage ride through process flag is true; if true, switching the unit control system from the normal power generation control mode to the low voltage ride through control mode; otherwise, maintaining the unit in the normal power generation control mode; in the low voltage ride through control mode, performing the transmission chain resistance adding adaptive control, the variable pitch response adaptive control and the advance variable pitch adaptive control in parallel; The transmission chain resistance adding adaptive control comprises: obtaining the transmission chain resistance adding limiting coefficient based on the table lookup method according to the time counted after the low voltage ride through flag is activated, and then multiplying the resistance adding torque output by the resistance adding device by the transmission chain resistance adding limiting coefficient to obtain the final resistance adding torque, thereby realizing dynamic adjustment of the resistance adding torque. The variable pitch response adaptive control comprises: calculating the current generator rotational acceleration GenAcc according to the generator speed, and if GenAcc is greater than a preset threshold GenAcc1, superimposing a preset variable pitch rate Pitchrate1 on the variable pitch rate Pitchrate output by the unified variable pitch PID controller to obtain the superimposed variable pitch rate. The advance variable pitch adaptive control comprises: first estimating the wind speed to obtain the estimated wind speed, and then obtaining the adaptive advance variable pitch value according to the estimated wind speed. S3, performing comprehensive control on the unit according to the final resistance adding torque, the superimposed variable pitch rate and the adaptive advance variable pitch value obtained in S2, so as to suppress power fluctuation and ensure the safety of the unit. In the advance variable pitch adaptive control in step S2, the calculation formula of the estimated wind speed v is: Wherein, P is power, ρ is air density, A is wind wheel area, and Cp is power coefficient. In the advance variable pitch adaptive control in step S2, an estimated wind speed-advance variable pitch value two-dimensional interpolation table is preset, wherein the estimated wind speed-advance variable pitch value two-dimensional interpolation table is preset with a mapping relationship between the estimated wind speed and the advance variable pitch value; by querying the estimated wind speed-advance variable pitch value two-dimensional interpolation table, the advance variable pitch value corresponding to the estimated wind speed can be obtained.

2. The method of adaptive control of a wind turbine during low voltage ride through according to claim 1, characterized in that, In the transmission chain resistance adding adaptive control in step S2, an activation time-transmission chain resistance adding limiting coefficient two-dimensional interpolation table is preset, wherein the activation time-transmission chain resistance adding limiting coefficient two-dimensional interpolation table is preset with a mapping relationship between the activation time and the transmission chain resistance adding limiting coefficient two-dimensional interpolation table; by querying the activation time-transmission chain resistance adding limiting coefficient two-dimensional interpolation table, the transmission chain resistance adding limiting coefficient corresponding to the activation time can be obtained; wherein the activation time is the time counted after the low voltage ride through flag is activated.

3. The method of adaptive control of a wind turbine during a low voltage ride through according to any of the claims 1-2, wherein In step S1, after obtaining the operation data, the operation data is cleaned and filtered.

4. The method of adaptive control of a wind turbine during a low voltage ride through according to any of the claims 1-2, wherein The preset variable pitch rate Pitchrate1 has a value range of 1-3 deg / s.

5. A wind turbine generator system adaptive control system during low voltage ride through comprising a memory and a processor connected to each other, the memory having a computer program stored thereon, characterized in that, The computer program, when executed by the processor, performs the steps of the method of any one of claims 1-4.

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