Control Method and System for Improving Power Generation of Large-Capacity Variable-Speed Wind Turbine Generators

Abstract

The present invention discloses a control method and system for improving the power generation of a large-capacity variable-speed wind turbine. The method includes: 1) reading the wind speed information of the sensor; 2) calculating the minimum rotational speed limit value; 3) performing a limiting process on the calculated minimum rotational speed limit value ω Min ; 4) modifying the actual minimum rotational speed limit parameter. The present invention can improve the power generation without the need to additionally increase hardware or sensor devices, and can obtain higher benefits without additional costs.

Description

Technical Field

[0001] The present invention relates to the technical field of wind power generation, and in particular to a control method and system for increasing the power generation of a large-capacity variable-speed wind turbine generator set. Background Art

[0002] The development of the single-unit capacity of wind turbine generator sets has been very rapid, especially for offshore units, and the single-unit capacity has exceeded 16 MW. The increase in the single-unit capacity means that the moment of inertia of the unit will also increase. When the wind turbine generator set is below the rated wind speed, the generator speed is adjusted by torque control to make it in the optimal tip speed ratio state, so as to obtain the best power generation power. However, considering the huge inertia force of the wind wheel of the large-moment-of-inertia wind turbine generator set, its dynamic tracking performance is inevitably slow, and it is difficult to balance the speed tracking performance for actual low wind speed conditions and high wind speed conditions. That is, with the frequent fluctuations of the actual turbulent wind on site, the large-inertia wind turbine generator set spends more time in the dynamic tracking process rather than operating at the steady-state operating point. Theoretically, this causes a loss of power generation. And the maximum wind energy that the wind turbine generator set can capture is proportional to the cube of the wind speed, that is, the wind energy contained in the low wind speed period is much less than that in the high wind speed period of the same duration. Based on this, improving the dynamic tracking performance for high wind speeds is more critical for power generation. Even if some dynamic tracking performance for low wind speeds is sacrificed, it can still bring an increase in power generation.

[0003] Currently, in the maximum power tracking control of conventional wind turbine generator sets, the increasing influence of the moment of inertia of the wind turbine generator set is rarely considered, and the same strategy is adopted for maximum power tracking in low wind speed and high wind speed conditions below the rated wind speed, which urgently needs to be improved. Summary of the Invention

[0004] The first object of the present invention is to overcome the deficiencies of the prior art and provide a control method for increasing the power generation of a large-capacity variable-speed wind turbine generator set, which can increase the power generation without the need to additionally increase hardware or sensor devices, and can obtain higher benefits without additional costs.

[0005] The second object of the present invention is to provide a control system for increasing the power generation of a large-capacity variable-speed wind turbine generator set.

[0006] The first object of the present invention is achieved by the following technical solution: A control method for increasing the power generation of a large-capacity variable-speed wind turbine generator set is based on the following formula:

[0007] The optimal speed of the wind turbine generator set below the rated wind speed is determined by the optimal tip speed ratio λ opt and the wind speed ν, as shown in Equation (1):

[0008]

[0009] In the formula, ω represents the generator speed, G represents the gearbox transmission ratio, and R represents the impeller radius;

[0010] Based on the above formula, the method uses the historical average wind speed in the previous 3 minutes as the prediction of the wind speed in the next cycle, and substitutes it into Equation (1) to take the calculated rotational speed value as the minimum limit value ω of the generator speed Min , and update Equation (1) to:

[0011]

[0012] Even if the actual wind speed at the next moment is lower than the historical average wind speed in the previous 3 minutes it will fluctuate and rise in the subsequent several cycles. Therefore, the generator speed is limited to ω Min , when the wind speed rises in the subsequent cycle, the wind turbine with the limited rotational speed will track the optimal rotational speed faster; of course, if the wind speed continues to drop for a long time, the historical average wind speed in the previous 3 minutes will drop later than the actual wind speed, and the wind turbine will also track the optimal rotational speed later, which sacrifices the tracking performance of the wind turbine for the weakening wind speed, and a part of the generated electricity will also be lost during this process; but when the wind speed rises, since the rotational speed of the wind turbine drops slowly, it can rise from a higher rotational speed value to the optimal rotational speed, which improves the tracking performance for the strengthening wind speed; since the wind energy contained in the low wind speed period is much less than that in the high wind speed period of the same duration, therefore, on the premise that the overall rise and fall changes of the wind conditions are average, the part of the increased benefit is obviously larger than the part of the sacrificed benefit;

[0013] In addition, in order to be able to flexibly adjust the degree of speed limit, an adjustment link η is introduced, and Equation (2) is updated to:

[0014]

[0015] In the formula, the adjustment link is a function of the historical average wind speed in the previous 3 minutes , and according to different wind speed segments, by different settings of the adjustment link η, the degree of the generator speed limit can be adjusted to obtain the best benefit.

[0016] Furthermore, the control method for the large-capacity variable-speed wind turbine to increase the generated electricity includes the following steps:

[0017] 1) Read the wind speed information of the sensor

[0018] After the wind turbine enters the normal power generation mode, it starts to collect the historical wind speed information from the lidar wind sensor and the ultrasonic sensor until the historical wind speed information for 3 minutes is collected;

[0019] 2) Calculate the minimum rotational speed limit

[0020] Obtain the historical average wind speed in the previous 3 minutes based on the 3-minute historical wind speed information Calculate the minimum rotational speed limit ω according to Equation (3) Min ;

[0021] 3) For the calculated minimum rotational speed limit ω Min Perform amplitude limiting processing

[0022] If the calculated minimum rotational speed limit ω Min is less than the grid connection rotational speed of the wind turbine generator set, the output is amplitude-limited to the grid connection rotational speed; if the calculated minimum rotational speed limit ω Min is greater than the rated rotational speed of the wind turbine generator set, the output is amplitude-limited to the rated rotational speed;

[0023] 4) Modify the actual minimum rotational speed limit parameter

[0024] If the blades of the wind turbine generator set start to retract and deviate from the optimal pitch angle, do not execute the modification of the actual minimum rotational speed limit parameter; if the wind turbine generator set pitches to the optimal pitch angle and maintains it at the optimal pitch angle for two minutes, then execute the modification of the actual minimum rotational speed limit parameter. Specifically, use the amplitude-limited minimum rotational speed limit ω Min to modify the actual minimum rotational speed limit parameter.

[0025] Furthermore, in step 1), a low-pass filter is used to filter the wind speed information.

[0026] The second object of the present invention is achieved through the following technical solution: A control system for increasing the power generation of a large-capacity variable-speed wind turbine generator set, comprising:

[0027] A sensor wind speed information reading module for collecting wind speed historical information;

[0028] A minimum rotational speed limit calculation module for calculating the minimum rotational speed limit;

[0029] An amplitude limiting processing module for performing amplitude limiting processing on the calculated minimum rotational speed limit;

[0030] A modification module for modifying the actual minimum rotational speed limit parameter.

[0031] Furthermore, the sensor wind speed information reading module starts to collect wind speed historical information from the lidar wind sensor and the ultrasonic sensor after the wind turbine generator set enters the normal power generation mode until 3 minutes of historical wind speed information is collected. Among them, a low-pass filter is used to filter the wind speed information.

[0032] Further, the minimum rotational speed limit calculation module calculates the historical average wind speed in the previous 3 minutes based on the 3-minute historical wind speed information. Calculate the minimum rotational speed limit ω according to the following formula: Min ;

[0033]

[0034] In the formula, G represents the gearbox transmission ratio, R represents the impeller radius, λ opt represents the optimal tip speed ratio, η represents the adjustment link, is a function of the historical average wind speed in the previous 3 minutes . By setting different values of the adjustment link η according to different wind speed segments, the degree of restriction on the generator rotational speed can be adjusted to obtain the best benefit.

[0035] Further, the amplitude limiting processing module specifically performs the following operations:

[0036] If the calculated minimum rotational speed limit ω Min is less than the grid connection rotational speed of the wind turbine generator set, the output will be amplitude-limited to the grid connection rotational speed; if the calculated minimum rotational speed limit ω Min is greater than the rated rotational speed of the wind turbine generator set, the output will be amplitude-limited to the rated rotational speed.

[0037] Further, the modification module specifically performs the following operations:

[0038] If the blades of the wind turbine generator set start to feather and deviate from the optimal pitch angle, the actual minimum rotational speed limit parameter will not be modified; if the blades of the wind turbine generator set are pitched to the optimal pitch angle and maintained at the optimal pitch angle for two minutes, the actual minimum rotational speed limit parameter will be modified. Specifically, the amplitude-limited minimum rotational speed limit ω Min is used to modify the actual minimum rotational speed limit parameter.

[0039] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0040] 1. The present invention can increase the power generation of the wind turbine generator set below the rated wind speed.

[0041] 2. The present invention does not require additional hardware devices or sensors, and there is no cost increase.

[0042] 3. The present invention does not cause obvious load changes compared with traditional control methods. Description of the Drawings

[0043] Figure 1 is a schematic diagram of the logic flow of the method of the present invention.

[0044] Figure 2 is a curve graph of power comparison in the simulation of the present invention.

[0045] Figure 3 This is the rotational speed comparison curve graph of the present invention in simulation.

[0046] Figure 4 This is the wind speed curve graph of the present invention in simulation.

[0047] Figure 5 This is the architecture diagram of the system of the present invention. Detailed implementation manners

[0048] The present invention will be further described in detail below in conjunction with embodiments and the accompanying drawings, but the implementation manners of the present invention are not limited thereto.

[0049] Embodiment 1

[0050] When the wind turbine generator is below the rated wind speed, the optimal rotational speed is determined by the optimal tip speed ratio λ opt and the wind speed v, as shown in Equation (1):

[0051]

[0052] In the formula, ω represents the rotational speed of the generator, G represents the gearbox transmission ratio, and R represents the radius of the impeller;

[0053] Based on the above formula, the control method for improving the power generation of the large-capacity variable-speed wind turbine generator provided in this embodiment uses the historical average wind speed in the previous 3 minutes as the prediction of the wind speed in the next cycle, and substitutes the calculated rotational speed value into Equation (1) as the minimum limit value ω Min of the rotational speed of the generator, and updates Equation (1) to:

[0054]

[0055] The idea of the above formula is that even if the actual wind speed at the next moment is lower than the historical average wind speed in the previous 3 minutes it will fluctuate and rise in the subsequent several cycles. Therefore, the rotational speed of the generator is limited to ω Min . When the wind speed rises in the subsequent cycles, the wind turbine generator with the limited rotational speed will track the optimal rotational speed faster; of course, if the wind speed continues to decrease for a long time, the historical average wind speed in the previous 3 minutes It will decline later compared to the actual wind speed, and the wind turbine will also track the optimal speed later, sacrificing the tracking performance of the wind turbine for weakening wind speed. A part of the generated power will also be lost during this process. However, when the wind speed rises, due to the slow decline in speed, the wind turbine can rise from a higher speed value to the optimal speed, which improves the tracking performance for strengthening wind speed. Since the wind energy contained in the low wind speed period is much less than that in the high wind speed period of the same duration, on the premise that the overall rise and fall changes in the wind conditions are average, the part of the increased benefit is obviously larger than the part of the sacrificed benefit.

[0056] In addition, in order to flexibly adjust the degree of speed limit, an adjustment link η is introduced, and Equation (2) is updated as:

[0057]

[0058] In the formula, the adjustment link is a function of the historical average wind speed in the previous 3 minutes . By setting different values of the adjustment link η according to different wind speed segments, the degree of generator speed limit can be adjusted to obtain the best benefit.

[0059] As Figure 1 shown, the control method for improving the power generation of the large-capacity variable-speed wind turbine provided in this embodiment includes the following steps:

[0060] 1) Read the wind speed information of the sensor

[0061] After the wind turbine enters the normal power generation mode, it starts to collect the historical wind speed information from the lidar wind sensor and the ultrasonic sensor until the historical wind speed information for 3 minutes is collected. Among them, a low-pass filter is used to filter the wind speed information.

[0062] 2) Calculate the minimum speed limit

[0063] Calculate the historical average wind speed in the previous 3 minutes based on the historical wind speed information for 3 minutes Calculate the minimum speed limit ω according to Equation (3) Min .

[0064] 3) Perform a limit processing on the calculated minimum speed limit ω Min

[0065] If the calculated minimum speed limit ω Min is less than the grid connection speed of the wind turbine, the output will be limited to the grid connection speed; if the calculated minimum speed limit ω Min is greater than the rated speed of the wind turbine, the output will be limited to the rated speed.

[0066] 4) Modify the actual minimum speed limit parameter

[0067] If the blade of the wind turbine starts to feather and deviate from the optimal pitch angle, the actual minimum speed limit parameter will not be modified; if the wind turbine pitches to the optimal pitch angle and maintains at the optimal pitch angle for two minutes continuously, the actual minimum speed limit parameter will be modified. Specifically, the limited minimum speed limit value ω Min is used to modify the actual minimum speed limit parameter.

[0068] Figures 2 to 4 The running effect of the above method in this embodiment in simulation is shown.

[0069] Embodiment 2

[0070] This embodiment discloses a control system for increasing the power generation of a large-capacity variable-speed wind turbine, as Figure 5 shown, including a sensor wind speed information reading module, a minimum speed limit value calculation module, a limiting processing module, and a modification module.

[0071] After the wind turbine enters the normal power generation mode, the sensor wind speed information reading module starts to collect the historical wind speed information from the lidar wind sensor and the ultrasonic sensor until 3 minutes of historical wind speed information is collected; among them, the low-pass filter is used to filter the wind speed information.

[0072] The minimum speed limit value calculation module calculates the historical average wind speed in the previous 3 minutes according to the 3-minute historical wind speed information and calculates the minimum speed limit value ω according to the following formula Min ;

[0073]

[0074] In the formula, G represents the gearbox transmission ratio, R represents the impeller radius, λ opt represents the optimal tip speed ratio, η represents the adjustment link, is a function of the historical average wind speed in the previous 3 minutes. By setting different adjustment links η according to different wind speed sections, the degree of restriction on the generator speed can be adjusted to obtain the best benefit.

[0075] The limiting processing module specifically performs the following operations:

[0076] If the calculated minimum speed limit value ω Min is less than the grid connection speed of the wind turbine, the output will be limited to the grid connection speed; if the calculated minimum speed limit value ω Min is greater than the rated speed of the wind turbine, the output will be limited to the rated speed.

[0077] The modification module specifically performs the following operations:

[0078] If the blade of the wind turbine starts to feather and deviate from the optimal pitch angle, the modification of the actual minimum speed limit parameter is not executed; if the wind turbine pitches to the optimal pitch angle and maintains at the optimal pitch angle for two minutes continuously, the modification of the actual minimum speed limit parameter is executed. Specifically, the limited minimum speed limit ω Min is used to modify the actual minimum speed limit parameter.

[0079] The above embodiments are the preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A control method for increasing the power generation of a large-capacity variable-speed wind turbine, characterized in that, Based on the following formula: The optimal rotational speed of a wind turbine below the rated wind speed is determined by the optimal tip speed ratio and the wind speed as shown in Equation (1): （1）； wherein, represents the generator speed, G represents the gearbox transmission ratio, and R represents the impeller radius; Based on the above formula, the method uses the historical average wind speed in the previous 3 minutes as the prediction of the wind speed in the next cycle, and substitutes the calculated rotational speed value into Equation (1) as the minimum limit value of the generator rotational speed , and updates Equation (1) to: （2）； Even if the actual wind speed at the next moment is lower than the historical average wind speed in the previous 3 minutes , it will fluctuate and rise in the subsequent several cycles. Therefore, the generator speed is limited to . When the wind speed rises in the subsequent cycles, the wind turbine with the limited speed will track the optimal speed faster; of course, if the wind speed continues to drop for a long time, the historical average wind speed in the previous 3 minutes will drop later than the actual wind speed, and the wind turbine will also track the optimal speed later, which sacrifices the tracking performance of the wind turbine for the weakening wind speed. A part of the power generation will also be lost during this process; but when the wind speed rises, since the speed of the wind turbine drops slowly, it can rise from a higher speed value to the optimal speed, which improves the tracking performance for the strengthening wind speed; since the wind energy contained in the low wind speed period is much smaller than that in the high wind speed period of the same duration, under the premise that the overall rise and fall changes of the wind conditions are average, the part that increases the profit is obviously larger than the part that sacrifices the profit; In addition, in order to flexibly adjust the degree of restriction on the rotational speed, an adjustment link is introduced , and Equation (2) is updated to: （3）； In the formula, the adjustment link is the historical average wind speed for the first 3 minutes is a function of. According to different wind speed segments, through different settings of the adjustment link , the degree of restriction on the generator speed can be adjusted to obtain the best benefit.

2. The control method for increasing the power generation of a large-capacity variable-speed wind turbine according to claim 1, characterized in that, Including the following steps: 1) Read the wind speed information of the sensor After the wind turbine generator enters the normal power generation mode, it starts to collect the historical wind speed information from the lidar wind sensor and the ultrasonic sensor until 3 minutes of historical wind speed information is collected; 2) Calculate the minimum rotational speed limit Calculate the historical average wind speed for the previous 3 minutes based on the 3-minute historical wind speed information , and calculate the minimum rotational speed limit according to Equation (3) ; 3) Perform a limiting process on the calculated minimum rotational speed limit value to perform a limiting process If the calculated minimum speed limit is less than the grid connection speed of the wind turbine, the output will be limited to the grid connection speed; if the calculated minimum speed limit is greater than the rated speed of the wind turbine, the output will be limited to the rated speed; 4) Modify the actual minimum rotational speed limit parameter If the blade of the wind turbine starts to feather and deviate from the optimal pitch angle, the actual minimum speed limit parameter will not be modified; if the wind turbine pitches to the optimal pitch angle and remains at the optimal pitch angle for two consecutive minutes, the actual minimum speed limit parameter will be modified. Specifically, the limited minimum speed limit value is used to modify the actual minimum speed limit parameter.

3. The control method for increasing the power generation of a large-capacity variable-speed wind turbine according to claim 2, characterized in that, In step 1), a low-pass filter is used to filter the wind speed information.

4. A control system for increasing the power generation of a large-capacity variable-speed wind turbine, characterized in that, A control method for improving the power generation of a large-capacity variable-speed wind turbine generator according to any one of claims 1-3, comprising: A sensor wind speed information reading module for collecting historical wind speed information; A minimum rotational speed limit calculation module for calculating the minimum rotational speed limit; A limiting processing module for performing a limiting process on the calculated minimum rotational speed limit; A modification module for modifying the actual minimum rotational speed limit parameter.

5. The control system for increasing the power generation of a large-capacity variable-speed wind turbine according to claim 4, characterized in that, The sensor wind speed information reading module starts to collect the historical wind speed information from the lidar wind sensor and the ultrasonic sensor after the wind turbine generator enters the normal power generation mode until 3 minutes of historical wind speed information is collected, wherein a low-pass filter is used to filter the wind speed information.

6. The control system for increasing the power generation of a large-capacity variable-speed wind turbine according to claim 5, characterized in that, The minimum rotational speed limit calculation module calculates the historical average wind speed in the previous three minutes based on the three-minute historical wind speed information , and calculates the minimum rotational speed limit according to the following formula ; ； Wherein, G represents the gearbox transmission ratio, and R represents the impeller radius, represents the optimal tip speed ratio, represents the adjustment link, is the historical average wind speed over the first 3 minutes as a function of, and through the adjustment link with different settings, the degree of restriction on the generator speed can be adjusted to obtain the best benefit.

7. The control system for increasing the power generation of a large-capacity variable-speed wind turbine according to claim 6, wherein, The limiting processing module specifically performs the following operations: If the calculated minimum speed limit is less than the grid connection speed of the wind turbine, the output will be limited to the grid connection speed; if the calculated minimum speed limit is greater than the rated speed of the wind turbine, the output will be limited to the rated speed.

8. The control system for increasing the power generation of a large-capacity variable-speed wind turbine according to claim 7, wherein, The modification module specifically performs the following operations: If the blade of the wind turbine starts to feather and deviate from the optimal pitch angle, the actual minimum speed limit parameter will not be modified; if the wind turbine pitches to the optimal pitch angle and maintains at the optimal pitch angle for two minutes continuously, the actual minimum speed limit parameter will be modified. Specifically, the limited minimum speed limit value is used to modify the actual minimum speed limit parameter.

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