A method and device for correcting optimal torque coefficient of a wind turbine

Abstract

The present application belongs to the field of wind power generation technology, and particularly relates to a wind power generator optimal torque coefficient correction method and device. First, when the wind power generator exits the maximum power tracking state, a plurality of data pairs of the wind power generator in the maximum power tracking state are obtained, one data pair including a wind energy utilization rate and a tip speed ratio corresponding to the wind energy utilization rate; then, the data pairs with the wind energy utilization rate greater than that in the balance state are selected from the obtained data pairs, and a standard tip speed ratio is calculated according to all the tip speed ratios in the selected data pairs; finally, the optimal torque coefficient is corrected by using the difference between the standard tip speed ratio and the tip speed ratio in the balance state, so that the error gradually decreases, and the optimal torque coefficient can be corrected slowly with the changes of the environment and the wind power generator parameters, and the optimal torque coefficient can be kept optimal for a long time by self-correction adjustment, and the power generation performance of the wind power generator is improved.

Description

Technical Field

[0001] This invention belongs to the field of wind power generation technology, specifically relating to a method and device for correcting the optimal torque coefficient of a wind turbine. Background Technology

[0002] To improve the power generation efficiency of wind turbine generators, maximum power point tracking (MPPT) is used most of the time. The most crucial control parameter in this algorithm is the optimal torque coefficient, the accuracy of which directly affects the control performance of the wind turbine, and consequently, its power generation efficiency. This parameter is calculated based on wind turbine parameters, rotor aerodynamic parameters, transmission chain parameters, and environmental variables. Its application in the wind turbine's control block diagram is shown below. Figure 1 As shown, the torque command of a wind turbine is calculated from the generator speed and the optimal torque coefficient, which is a pre-set setpoint parameter Kopt. Field operation data indicates that the aerodynamic parameters provided by the wind turbine manufacturer may have deviations, so the optimal torque coefficient Kopt needs to be calibrated on-site. Furthermore, after the wind turbine has been running for a certain period, the aerodynamic parameters of the wind turbine will also change, so the optimal torque coefficient needs to be recalibrated. The currently commonly used technical solution is to set the optimal torque coefficient as a fixed value and not modify it. However, wind turbine parameters will have errors, and wind turbine parameters and environmental variables will change over time. The setpoint Kopt will obviously affect the power generation of the wind turbine and cannot guarantee that the wind turbine is in its optimal operating state. Summary of the Invention

[0003] The purpose of this invention is to provide a method and apparatus for correcting the optimal torque coefficient of a wind turbine, so as to solve the problem of the impact on the power generation of the wind turbine caused by setting the optimal torque coefficient to a fixed value in the prior art.

[0004] To address the aforementioned technical problems, this invention provides a method for correcting the optimal torque coefficient of a wind turbine generator, comprising the following steps:

[0005] 1) When the wind turbine exits the maximum power tracking state, acquire multiple data pairs when the wind turbine is in the maximum power tracking state. Each data pair includes the wind energy utilization rate and the tip speed ratio corresponding to the wind energy utilization rate.

[0006] 2) Filter out the data pairs from the acquired data pairs where the wind energy utilization rate is greater than that in the equilibrium state, and calculate the standard tip speed ratio based on all the tip speed ratios in the filtered data pairs; where the equilibrium state refers to the state where the tip speed ratio fluctuation amplitude is less than the set threshold.

[0007] 3) The corrected optimal torque coefficient is calculated using the following formula: Kopt′ represents the corrected optimal torque coefficient, and Kopt represents the uncorrected optimal torque coefficient. λ represents the standard tip speed ratio, λ0 represents the tip speed ratio at equilibrium, and k is a correction factor and k > 0.

[0008] Its beneficial effects are as follows: This invention uses the operating data of a wind turbine in maximum power tracking mode to select data pairs where the wind energy utilization rate is greater than that in the equilibrium state. Then, it uses all the tip speed ratios in the selected data pairs to calculate the standard tip speed ratio. Finally, it uses the difference between the standard tip speed ratio and the tip speed ratio in the equilibrium state to correct the optimal torque coefficient, so that its error gradually decreases. It can also correct the optimal torque coefficient as the environment and wind turbine parameters change slowly. With self-correction and adjustment, the optimal torque coefficient can be maintained at the optimal value for a long time, thereby improving the power generation performance of the wind turbine.

[0009] Further, in step 2), the standard tip speed ratio is the average of all tip speed ratios in the selected data pairs.

[0010] Furthermore, the formula for calculating wind energy utilization rate is:

[0011]

[0012] In the formula, C p Indicates wind energy utilization rate; w e w m ρ, S, and v represent the generator's electrical energy output, the increase in the wind turbine's mechanical energy, the air density of the wind farm, the swept area of ​​the wind turbine, and the wind speed, respectively, during the sampling period; ξ and ω t ω t+T Let represent the wind turbine's moment of inertia, the wind turbine's rotational speed at time t, and the wind turbine's rotational speed at time t+T, respectively, where T represents the sampling period.

[0013] Furthermore, the formula for calculating the tip speed ratio is:

[0014]

[0015] In the formula, λ represents the tip speed ratio, ω represents the rotor speed, v represents the wind speed, and R represents the rotor radius.

[0016] Furthermore, v represents the corrected wind speed value.

[0017] Its beneficial effects are: using the corrected wind speed value for calculation can eliminate the deviation between the wind cup and wind direction instrument data, ensuring the accuracy of wind energy utilization rate and tip speed ratio calculation.

[0018] Furthermore, the initial value of the optimal torque coefficient is set based on the wind turbine parameters and environmental parameters.

[0019] To address the aforementioned technical problems, the present invention also provides a wind turbine optimal torque coefficient correction device, comprising a memory and a processor. The processor is used to execute computer program instructions stored in the memory to implement the wind turbine optimal torque coefficient correction method described above, and achieve the same beneficial effects as the method. Attached Figure Description

[0020] Figure 1 This is a block diagram of the control strategy for maximum power point tracking control of existing wind turbines;

[0021] Figure 2 This is a block diagram of the control strategy for the maximum power point tracking control of a wind turbine generator with torque coefficient self-correction function according to the present invention.

[0022] Figure 3 This is a flowchart of the optimal torque coefficient correction method for wind turbine generators according to the present invention. Detailed Implementation

[0023] This invention corrects the optimal torque coefficient based on operating data of a wind turbine in maximum power point tracking (MPPT) mode, enabling the optimal torque coefficient to maintain its optimal value over a long period, thereby improving the power generation performance of the wind turbine. To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0024] Method Implementation Examples:

[0025] This invention proposes a control block diagram for a wind turbine maximum power point tracking control strategy with self-correction function, as shown in the figure below. Figure 2 As shown, the initial value of the optimal torque coefficient Kopt in this control strategy is still calculated from the wind turbine parameters and environmental data. However, the self-calibration module will adjust the optimal torque coefficient Kopt according to the wind turbine operating data, so that its error gradually decreases. It can also correct the optimal torque coefficient Kopt as the environment and wind turbine parameters change slowly. With the help of self-calibration, the optimal torque coefficient can maintain the optimal value for a long time, and the power generation performance of the wind turbine is improved.

[0026] The self-calibration module collects generator speed, power output, wind speed, and wind direction data at regular intervals, statistically analyzes the wind power operation data, and obtains the correction data for the optimal torque coefficient Kopt. The flowchart of the self-calibration module's data calculation and processing is shown below. Figure 3 As shown, the specific process is as follows:

[0027] 1) Collect necessary information data at certain intervals, including generator speed, power output, wind speed and wind direction data, and filter these data to obtain maximum power point tracking operation data for subsequent processing.

[0028] 2) Correct the wind speed and direction data. This step is necessary because the wind cup and anemometer data may have discrepancies, so the wind speed and direction data need to be corrected before use. If the wind turbine is equipped with a laser anemometer, the laser anemometer data can be used directly without correction.

[0029] 3) Calculate the wind energy utilization rate C of the wind turbine generator. p The tip speed ratio λ is calculated using the following formula:

[0030]

[0031]

[0032] In the formula, w e w m ρ, R, S, v, and ω represent the generator's electrical energy output, the increase in the wind turbine's mechanical energy, the air density of the wind farm, the wind turbine radius, the wind turbine swept area, the wind speed correction value, and the wind turbine rotational speed, respectively, within the sampling period; ξ and ω t ω t+T These represent the wind turbine's moment of inertia, the wind turbine's rotational speed at time t, and the wind turbine's rotational speed at time t+T, respectively, where T represents the sampling period of the self-calibration module.

[0033] If the tip speed ratio is stable, i.e., the amplitude of the λ fluctuation is close to zero, then update the parameter C corresponding to the equilibrium state. p 0 = C p , λ0=λ.

[0034] 4) If the wind turbine is operating in maximum power point tracking mode, then the data pair (C) p ,λ) are recorded in the memory for data statistical analysis; if the wind turbine is exiting the maximum power point tracking state, the data generated during the current wind turbine operation's maximum power point tracking process is read from the memory for statistical analysis, and step 5 is executed.

[0035] 5) Iterate through all data pairs (C p ,λ), if C p >C p If the value is 0, then the corresponding tip speed ratio λ is marked as λ. u and put all the λ u Calculate the average value to obtain

[0036] 6) Correct the optimal torque coefficient Kopt, and its update formula is as follows:

[0037]

[0038] In the formula, Kopt′ and Kopt represent the optimal torque coefficients before and after correction, respectively; k is the correction factor, k>0. The larger the value of k, the easier it is for the system to lose stability, and vice versa. However, the correction speed of Kopt is slower. The value of k is obtained from the field commissioning test.

[0039] After obtaining the corrected optimal torque coefficient Kopt′, the generator torque command can be calculated using the generator speed and the optimal torque coefficient, and then used to control the wind turbine. Figure 3 As can be seen from the process, the optimal torque coefficient Kopt correction is based on wind turbine operating data rather than wind turbine parameters. Therefore, the initial Kopt deviation caused by wind turbine parameter errors will gradually disappear during the self-correction process. Changes in the environment and wind turbine parameters will be reflected in the wind turbine operating data. The torque coefficient self-correction module can correct the optimal torque coefficient Kopt based on the wind turbine operating data, adapting it to new environmental parameters and changed wind turbine parameters. Through self-correction adjustment, the optimal torque coefficient can maintain its optimal value for a long period, thus improving the power generation performance of the wind turbine.

[0040] Device Example:

[0041] An embodiment of the optimal torque coefficient correction device for a wind turbine generator according to the present invention includes a memory, a processor, and an internal bus. The processor and the memory communicate and exchange data with each other through the internal bus. The memory is used to execute computer program instructions stored in the memory, which can implement the optimal torque coefficient correction method for a wind turbine generator described in the method embodiment of the present invention. The processor can be a microprocessor (MCU), a programmable logic device (FPGA), or other processing devices. The memory can be any type of memory that stores information using electrical energy, such as RAM, ROM, etc., and of course, other types of memory are also possible.

Claims

1. A method for correcting the optimal torque coefficient of a wind turbine generator, characterized in that, Includes the following steps: 1) When the wind turbine exits the maximum power tracking state, acquire multiple data pairs when the wind turbine is in the maximum power tracking state. Each data pair includes the wind energy utilization rate and the tip speed ratio corresponding to the wind energy utilization rate. 2) Filter out the data pairs from the acquired data pairs where the wind energy utilization rate is greater than that in the equilibrium state, and calculate the average value of all tip speed ratios in the filtered data pairs to obtain the standard tip speed ratio; where the equilibrium state refers to the state where the tip speed ratio fluctuation amplitude is less than the set threshold. 3) The corrected optimal torque coefficient is calculated using the following formula: , This represents the corrected optimal torque coefficient. This represents the optimal torque coefficient before correction. Indicates the standard tip speed ratio. This represents the tip speed ratio at equilibrium. As a correction factor and .

2. The method for correcting the optimal torque coefficient of a wind turbine generator according to claim 1, characterized in that, This was obtained through on-site commissioning and testing.

3. The method for correcting the optimal torque coefficient of a wind turbine generator according to claim 1, characterized in that, The formula for calculating wind energy utilization rate is: In the formula, Indicates wind energy utilization rate; , , , , These represent the generator electrical energy output, wind turbine mechanical energy increase, wind farm air density, wind turbine swept area, wind speed value or corrected wind speed value during the sampling period, respectively. , , Let represent the wind turbine's moment of inertia, the wind turbine's rotational speed at time t, and the wind turbine's rotational speed at time t+T, respectively, where T represents the sampling period.

4. The method for correcting the optimal torque coefficient of a wind turbine generator according to claim 1, characterized in that, The formula for calculating the tip speed ratio is: In the formula, Indicates the tip speed ratio. Indicates the wind turbine speed. This represents the wind speed value or the corrected wind speed value. Indicates the radius of the wind turbine.

5. The method for correcting the optimal torque coefficient of a wind turbine generator according to claim 1, characterized in that, The method also includes: calculating the generator torque command using the generator speed and the corrected optimal torque coefficient, and using the generator torque command to control the wind turbine.

6. The method for correcting the optimal torque coefficient of a wind turbine generator according to claim 1, characterized in that, The initial value of the optimal torque coefficient is set based on the wind turbine parameters and environmental parameters.

7. A wind turbine optimal torque coefficient correction device, characterized in that, It includes a memory and a processor, the processor being configured to execute computer program instructions stored in the memory to implement the optimal torque coefficient correction method for wind turbines as described in any one of claims 1 to 6.

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