Method and system for attenuating second-order vibration and load in the front-to-back direction of a wind turbine tower

Abstract

The invention discloses a method and system for attenuating the second-order vibration and load of a wind turbine tower in the front-to-back direction. The method comprises the following steps: obtaining a speed signal in the front-to-back direction of a nacelle and filtering the signal to obtain a second-order natural frequency component in the speed in the front-to-back direction of the nacelle; subtracting the second-order natural frequency component from a target given value; using the difference as an input of a d-axis proportional integral controller in a dq stationary coordinate system; outputting a d-axis variable pitch position given value; calculating the d-axis and q-axis variable pitch position given values ​​and a real-time impeller azimuth through an inverse Park transformation; obtaining respective blade angle compensation values ​​of three blades controlled by IPC, and superimposing the values ​​on a unified variable pitch blade angle given value to obtain the variable pitch position given values ​​of the three blades; and executing the variable pitch position given values ​​of the three blades by respective variable pitch actuators to realize the IPC control function, thereby achieving the purpose of attenuating the second-order natural frequency vibration in the front-to-back direction of the tower and reducing the second-order natural frequency load in the front-to-back direction of the tower.

Description

Technical Field

[0001] The present invention relates to the technical field of wind power generation, and in particular to a method and system for attenuating second-order vibration and load in the front-rear direction of a tower of a wind turbine generator set. Background Art

[0002] In onshore wind farms with low average wind speed and high vertical wind shear, high-power, long-blade flexible high-tower wind turbines are widely used. As the height of the flexible tower continues to increase, although the flexible tower unit is equipped with a mechanical damper on the platform at the middle height of the tower to attenuate the first-order natural frequency vibration of the tower and the second-order natural frequency vibration, when the unit reaches the rated speed, within the range from the middle of the tower to the cabin height of the wind turbine unit, the second-order natural frequency vibration in the front-to-back direction of the tower and the second-order natural frequency load in the front-to-back direction of the tower are still relatively large. Summary of the invention

[0003] The first purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art and to provide a method based on IPC control that can effectively attenuate the second-order vibration and load in the front-to-back direction of the wind turbine tower.

[0004] The second object of the present invention is to provide a system based on IPC control that can effectively attenuate the second-order vibration and load of the wind turbine tower in the front-to-back direction.

[0005] The first object of the present invention is achieved by the following technical solution: a method for attenuating the second-order vibration and load in the front-to-back direction of a wind turbine tower, comprising the following steps:

[0006] In the grid-connected power generation mode of the wind turbine, the acceleration signal of the front and rear directions of the nacelle is obtained;

[0007] The acceleration signal in the front and rear direction of the cabin is integrated to obtain the velocity signal in the front and rear direction of the cabin, and then the velocity signal in the front and rear direction of the cabin is filtered by a notch filter and a bandpass filter in sequence to obtain the second-order natural frequency component in the velocity in the front and rear direction of the cabin;

[0008] Subtract the second-order natural frequency component of the nacelle forward and backward speed from its target given value, and use the difference as the input of the d-axis proportional-integral controller in the dq stationary coordinate system. The output of the d-axis proportional-integral controller is the d-axis pitch position given value.

[0009] The d-axis pitch position given value, the q-axis pitch position given value and the real-time impeller azimuth in the grid-connected power generation mode of the wind turbine are calculated by inverse Park transformation from the dq stationary coordinate system to the rotating coordinate system to obtain the respective blade angle compensation values ​​of the three blades under IPC control. The respective blade angle compensation values ​​calculated by the IPC control of the three blades are superimposed on the unified pitch blade angle given value of the wind turbine to obtain the respective blade real-time angle given values ​​of the three blades, that is, the pitch position given values ​​of the three blades;

[0010] The pitch position set values ​​of the three blades are respectively executed by their respective pitch actuators to realize the IPC control function, thereby achieving the purpose of attenuating the second-order natural frequency vibration in the front-to-back direction of the tower and reducing the second-order natural frequency load in the front-to-back direction of the tower.

[0011] Furthermore, the specific calculation of the pitch position given values ​​of the three blades is as follows:

[0012]

[0013] Where β1, β2, and β3 are the pitch position given values ​​of blade 1, blade 2, and blade 3 respectively; is the real-time impeller azimuth angle of the wind turbine in grid-connected power generation mode; β d , β q are the given values ​​of the d-axis and q-axis pitch positions in the dq stationary coordinate system respectively; β c is the given value of the uniform pitch blade angle.

[0014] Furthermore, the transfer function of the notch filter is:

[0015]

[0016] Where s is a complex variable, ξ1 and ξ2 are the damping ratios of the notch filter, and ω1 and ω2 are the frequencies of the notch filter;

[0017] The transfer function of the bandpass filter is:

[0018]

[0019] Where G is the bandpass filter gain, ξ3 is the bandpass filter damping ratio, ω3 is the bandpass filter frequency, and τ is the bandpass filter time constant.

[0020] Furthermore, the uniform variable pitch blade angle given value is calculated by a generator speed VS variable pitch position proportional integral PI controller.

[0021] Furthermore, the acceleration signal in the front-rear direction of the nacelle is provided by a vibration sensor installed inside the nacelle; and the real-time impeller azimuth angle is provided by an absolute value rotary encoder installed in the wheel hub.

[0022] The second object of the present invention is achieved by the following technical solution: a system for attenuating the second-order vibration and load in the front-to-back direction of a wind turbine tower, comprising:

[0023] The data acquisition module is used to obtain the acceleration signal of the front and rear directions of the nacelle and the real-time impeller azimuth angle in the grid-connected power generation mode of the wind turbine;

[0024] A data processing module is used to integrate the acceleration signal in the front-to-back direction of the cabin to obtain the speed signal in the front-to-back direction of the cabin, filter the speed signal in the front-to-back direction of the cabin through a notch filter and a bandpass filter in sequence, obtain the second-order natural frequency component in the speed in the front-to-back direction of the cabin, subtract the second-order natural frequency component in the speed in the front-to-back direction of the cabin from its target given value, and use the difference as the input of the d-axis proportional-integral controller in the dq stationary coordinate system, and the output of the d-axis proportional-integral controller is the d-axis variable pitch position given value;

[0025] The pitch position given value calculation module is used to calculate the d-axis pitch position given value, the q-axis pitch position given value and the real-time impeller azimuth angle through inverse Park transformation from the dq stationary coordinate system to the rotating coordinate system, so as to obtain the respective blade angle compensation values ​​of the three blades under IPC control, and then superimpose the respective blade angle compensation values ​​calculated by the IPC control of the three blades on the unified pitch blade angle given value of the wind turbine, so as to obtain the respective blade real-time angle given values ​​of the three blades, that is, the pitch position given values ​​of the three blades;

[0026] The sending module is used to send the pitch position given values ​​of the three blades to the pitch actuators of their respective blades for execution, thereby realizing the IPC control function, thereby achieving the purpose of attenuating the second-order natural frequency vibration in the front-to-back direction of the tower and reducing the second-order natural frequency load in the front-to-back direction of the tower.

[0027] Furthermore, the specific calculation of the pitch position given values ​​of the three blades is as follows:

[0028]

[0029] Where β1, β2, and β3 are the pitch position given values ​​of blade 1, blade 2, and blade 3 respectively; is the real-time impeller azimuth angle of the wind turbine in grid-connected power generation mode; β d , β q are the given values ​​of the d-axis and q-axis pitch positions in the dq stationary coordinate system respectively; β c is the given value of the uniform pitch blade angle.

[0030] Furthermore, the transfer function of the notch filter is:

[0031]

[0032] Where s is a complex variable, ξ1 and ξ2 are the damping ratios of the notch filter, and ω1 and ω2 are the frequencies of the notch filter;

[0033] The transfer function of the bandpass filter is:

[0034]

[0035] Where G is the bandpass filter gain, ξ3 is the bandpass filter damping ratio, ω3 is the bandpass filter frequency, and τ is the bandpass filter time constant.

[0036] Furthermore, the uniform variable pitch blade angle given value is calculated by a generator speed VS variable pitch position proportional integral PI controller.

[0037] Furthermore, the acceleration signal in the front-rear direction of the nacelle is provided by a vibration sensor installed inside the nacelle; and the real-time impeller azimuth angle is provided by an absolute value rotary encoder installed in the wheel hub.

[0038] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0039] 1. With the IPC control function, the second-order natural frequency vibration of the tower in the front and rear directions can be effectively attenuated when the unit reaches the rated speed.

[0040] 2. Greatly reduce the second-order natural frequency load in the front-to-rear direction of the tower of the flexible tower unit, and improve the operating stability of the unit when it reaches the rated speed.

[0041] 3. No need to add any additional hardware equipment, which is economical. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 Schematic diagram of the method of the present invention.

[0043] Figure 2 It is the open-loop Bode diagram of the d-axis pitch position given value VS the acceleration in the forward and backward directions of the cabin when the IPC control function is turned on and off.

[0044] Figure 3 This is a comparison diagram of the acceleration timing of the cabin in the front and rear directions when the IPC control function of the soft tower unit is turned on and off.

[0045] Figure 4 This is a comparison chart of the acceleration spectrum in the front and rear directions of the cabin when the IPC control function of the soft tower unit is turned on and off.

[0046] Figure 5 This is a timing comparison diagram of the bending moment My in the front-to-back direction of the tower at a height of 88 meters when the IPC control function of the flexible tower unit is turned on and off.

[0047] Figure 6 This is a comparison chart of the frequency spectrum of the bending moment My in the front-to-back direction of the tower at a height of 88 meters when the IPC control function of the flexible tower unit is turned on and off.

[0048] Figure 7 This is the timing diagram of the blade angles of the three blades when the IPC control function of the flexible tower unit is turned on.

[0049] Figure 8 Schematic diagram of the system of the present invention. DETAILED DESCRIPTION

[0050] The present invention is further described in detail below in conjunction with embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0051] Example 1

[0052] For onshore high-power, long-blade, flexible high-tower wind turbines, this embodiment discloses a method based on IPC control that can effectively attenuate the second-order vibration and load in the front-to-back direction of the wind turbine tower, such as Figure 1 The specific situation is as follows:

[0053] In the grid-connected power generation mode of the wind turbine, the acceleration signal of the front and rear directions of the nacelle and the real-time impeller azimuth angle are obtained respectively. Among them, the acceleration signal of the front and rear directions of the nacelle is provided by the vibration sensor installed inside the nacelle, and the real-time impeller azimuth angle is provided by the absolute value rotary encoder installed in the hub.

[0054] The acceleration signal in the front and rear direction of the cabin is integrated to obtain the velocity signal in the front and rear direction of the cabin. The velocity signal in the front and rear direction of the cabin is then filtered by a notch filter and a bandpass filter in sequence to obtain the second-order natural frequency component in the velocity in the front and rear direction of the cabin. The corresponding transfer functions of the notch filter and the bandpass filter are as follows:

[0055] The transfer function of the notch filter is:

[0056]

[0057] Where s is a complex variable, ξ1 and ξ2 are the damping ratios of the notch filter, and ω1 and ω2 are the frequencies of the notch filter;

[0058] The transfer function of the bandpass filter is:

[0059]

[0060] Where G is the bandpass filter gain, ξ3 is the bandpass filter damping ratio, ω3 is the bandpass filter frequency, and τ is the bandpass filter time constant.

[0061] The second-order natural frequency component of the nacelle forward and backward speed is subtracted from its target given value, and the difference is used as the input of the d-axis proportional integral controller (i.e., d-axis proportional integral controller) in the dq stationary coordinate system. The output of the d-axis proportional integral controller is the d-axis variable pitch position given value.

[0062] The d-axis pitch position given value, the q-axis pitch position given value and the real-time impeller azimuth angle are calculated from the dq stationary coordinate system to the rotating coordinate system through the inverse Park transformation to obtain the respective blade angle compensation values ​​of the three blades under IPC control. The respective blade angle compensation values ​​calculated by the IPC control of the three blades are superimposed on the unified pitch blade angle given value calculated by the generator speed VS pitch position proportional integral PI controller to obtain the respective blade real-time angle given values ​​of the three blades, that is, the pitch position given values ​​of the three blades. The specific calculation is as follows:

[0063]

[0064] Where β1, β2, and β3 are the pitch position given values ​​of blade 1, blade 2, and blade 3 respectively; is the real-time impeller azimuth angle of the wind turbine in grid-connected power generation mode; β d , β q are the given values ​​of the d-axis and q-axis pitch positions in the dq stationary coordinate system respectively; β c is the given value of the uniform pitch blade angle.

[0065] Finally, the pitch position set values ​​of the three blades are executed by their respective pitch actuators to realize the IPC control function, thereby achieving the purpose of attenuating the second-order natural frequency vibration in the front-to-back direction of the tower and reducing the second-order natural frequency load in the front-to-back direction of the tower.

[0066] like Figure 2 As shown, it shows the comparison of the open-loop bode diagram of the d-axis pitch position given value VS the nacelle front-to-back speed when the IPC control function is turned on and off. When the IPC control function is turned on, there is a relatively large attenuation near the second-order natural frequency component in the front-to-back direction of the unit tower.

[0067] like Figure 3 , Figure 4 As shown, the acceleration timing of the cabin in the front and rear directions when the IPC control function of the unit is turned on and off and the corresponding frequency spectrum comparison are respectively shown. When the IPC control function is turned on, the attenuation amplitude is relatively large near the second-order natural frequency component in the front and rear directions of the tower.

[0068] like Figure 5 , Figure 6As shown, the timing of the bending moment My in the front-to-back direction of the tower at a height of 88 meters and the corresponding frequency spectrum comparison are shown when the IPC control function of the unit is turned on and off. When the IPC control function is turned on, the attenuation amplitude is relatively large near the second-order natural frequency component in the front-to-back direction of the tower.

[0069] like Figure 7 As shown, the timing of the blade angles of the three blades is shown when the IPC control function of the unit is turned on. The real-time maximum deviation of the blade angles of the three blades is controlled within 2.0deg. Compared with when the independent pitch control that reduces the 1P frequency component in the blade flapping direction bending moment is turned on, there is a maximum real-time deviation of 7-8deg between the blade angles. Therefore, the real-time deviation between the blade angles of the present invention is greatly reduced, and the application risk of independent pitch control is relatively small.

[0070] Example 2

[0071] For onshore high-power, long-blade, flexible high-tower wind turbines, this embodiment discloses a system based on IPC control that can effectively attenuate the second-order vibration and load in the front-to-back direction of the wind turbine tower, such as Figure 8 As shown, the system includes the following functional modules:

[0072] The data acquisition module is used to obtain the acceleration signal of the front and rear directions of the nacelle and the real-time impeller azimuth angle in the grid-connected power generation mode of the wind turbine set; wherein the acceleration signal of the front and rear directions of the nacelle is provided by a vibration sensor installed inside the nacelle, and the real-time impeller azimuth angle is provided by an absolute value rotary encoder installed in the hub.

[0073] The data processing module is used to integrate the acceleration signal in the front-to-back direction of the cabin to obtain the speed signal in the front-to-back direction of the cabin, filter the speed signal in the front-to-back direction of the cabin through a notch filter and a bandpass filter in sequence, obtain the second-order natural frequency component in the front-to-back direction of the cabin speed, subtract the second-order natural frequency component in the front-to-back direction of the cabin speed from its target given value, and use the difference as the input of the d-axis proportional integral controller (i.e., d-axis proportional integral controller) in the dq stationary coordinate system, and the output of the d-axis proportional integral controller is the d-axis variable pitch position given value; wherein, the corresponding transfer functions of the notch filter and the bandpass filter are as follows:

[0074] The transfer function of the notch filter is:

[0075]

[0076] Where s is a complex variable, ξ1 and ξ2 are the damping ratios of the notch filter, and ω1 and ω2 are the frequencies of the notch filter;

[0077] The transfer function of the bandpass filter is:

[0078]

[0079] Where G is the bandpass filter gain, ξ3 is the bandpass filter damping ratio, ω3 is the bandpass filter frequency, and τ is the bandpass filter time constant.

[0080] The pitch position given value calculation module is used to calculate the d-axis pitch position given value, the q-axis pitch position given value and the real-time impeller azimuth angle through the inverse Park transformation from the dq stationary coordinate system to the rotating coordinate system, and obtain the respective blade angle compensation values ​​of the three blades under IPC control. Then, the respective blade angle compensation values ​​calculated by the three blades IPC control are superimposed on the unified pitch blade angle given value calculated by the generator speed VS pitch position proportional integral PI controller to obtain the respective blade real-time angle given values ​​of the three blades, that is, the pitch position given values ​​of the three blades. The specific calculation is as follows:

[0081]

[0082] Where β1, β2, and β3 are the pitch position given values ​​of blade 1, blade 2, and blade 3 respectively; is the real-time impeller azimuth angle of the wind turbine in grid-connected power generation mode; β d , β q are the given values ​​of the d-axis and q-axis pitch positions in the dq stationary coordinate system respectively; β c is the given value of the uniform pitch blade angle.

[0083] The sending module is used to send the pitch position given values ​​of the three blades to the pitch actuators of their respective blades for execution, thereby realizing the IPC control function, thereby achieving the purpose of attenuating the second-order natural frequency vibration in the front-to-back direction of the tower and reducing the second-order natural frequency load in the front-to-back direction of the tower.

[0084] Example 3

[0085] This embodiment discloses a storage medium storing a program. When the program is executed by a processor, the method for attenuating the second-order vibration and load of the wind turbine tower in the front-to-rear direction described in Embodiment 1 is implemented.

[0086] The storage medium in this embodiment can be a disk, an optical disk, a computer memory, a read-only memory (ROM), a random access memory (RAM), a USB flash drive, a mobile hard disk, or other media.

[0087] Example 4

[0088] This embodiment discloses a computing device, including a processor and a memory for storing programs executable by the processor. When the processor executes the program stored in the memory, the method of attenuating the second-order vibration and load in the front-to-rear direction of the wind turbine tower described in Example 1 is implemented.

[0089] The computing device described in this embodiment may be a desktop computer, a laptop computer, a smart phone, a PDA handheld terminal, a tablet computer, a programmable logic controller (PLC), or other terminal devices with a processor function.

[0090] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for attenuating the second-order vibration and load of a wind turbine tower in the front-to-back direction, characterized in that: The following steps are involved: In the grid-connected power generation mode of the wind turbine, the acceleration signal of the front and rear directions of the nacelle is obtained; The acceleration signal in the front and rear direction of the cabin is integrated to obtain the velocity signal in the front and rear direction of the cabin, and then the velocity signal in the front and rear direction of the cabin is filtered by a notch filter and a bandpass filter in sequence to obtain the second-order natural frequency component in the velocity in the front and rear direction of the cabin; Subtract the second-order natural frequency component of the nacelle forward and backward speed from its target given value, and use the difference as the input of the d-axis proportional-integral controller in the dq stationary coordinate system. The output of the d-axis proportional-integral controller is the d-axis pitch position given value. The d-axis pitch position given value, the q-axis pitch position given value and the real-time impeller azimuth in the grid-connected power generation mode of the wind turbine are calculated by inverse Park transformation from the dq stationary coordinate system to the rotating coordinate system to obtain the respective blade angle compensation values ​​of the three blades under IPC control. The respective blade angle compensation values ​​calculated by the IPC control of the three blades are superimposed on the unified pitch blade angle given value of the wind turbine to obtain the respective blade real-time angle given values ​​of the three blades, that is, the pitch position given values ​​of the three blades; The pitch position setting values ​​of the three blades are respectively executed by their respective pitch actuators to realize the IPC control function, thereby achieving the purpose of attenuating the second-order natural frequency vibration in the front-to-back direction of the tower and reducing the second-order natural frequency load in the front-to-back direction of the tower; The specific calculation of the pitch position given values ​​of the three blades is as follows: Where β1, β2, and β3 are the pitch position given values ​​of blade 1, blade 2, and blade 3 respectively; is the real-time impeller azimuth angle of the wind turbine in grid-connected power generation mode; β d , β q are the given values ​​of the d-axis and q-axis pitch positions in the dq stationary coordinate system respectively; β c is a given value for the uniform pitch blade angle; The transfer function of the notch filter is: Where s is a complex variable, ξ1 and ξ2 are the damping ratios of the notch filter, and ω1 and ω2 are the frequencies of the notch filter; The transfer function of the bandpass filter is: Where G is the bandpass filter gain, ξ3 is the bandpass filter damping ratio, ω3 is the bandpass filter frequency, and τ is the bandpass filter time constant.

2. The method for attenuating the second-order vibration and load of the wind turbine tower in the front-to-back direction according to claim 1 is characterized in that: The uniform variable pitch blade angle given value is calculated by the generator speed VS variable pitch position proportional integral PI controller.

3. The method for attenuating the second-order vibration and load of the wind turbine tower in the front-to-back direction according to claim 1 is characterized in that: The acceleration signal in the front-rear direction of the nacelle is provided by a vibration sensor installed inside the nacelle; the real-time impeller azimuth angle is provided by an absolute value rotary encoder installed in the wheel hub.

4. A system for attenuating the second-order vibration and load in the front-to-back direction of a wind turbine tower, characterized in that: include: The data acquisition module is used to obtain the acceleration signal of the front and rear directions of the nacelle and the real-time impeller azimuth angle in the grid-connected power generation mode of the wind turbine; A data processing module is used to integrate the acceleration signal in the front-to-back direction of the cabin to obtain the speed signal in the front-to-back direction of the cabin, filter the speed signal in the front-to-back direction of the cabin through a notch filter and a bandpass filter in sequence, obtain the second-order natural frequency component in the speed in the front-to-back direction of the cabin, subtract the second-order natural frequency component in the speed in the front-to-back direction of the cabin from its target given value, and use the difference as the input of the d-axis proportional-integral controller in the dq stationary coordinate system, and the output of the d-axis proportional-integral controller is the d-axis variable pitch position given value; The pitch position given value calculation module is used to calculate the d-axis pitch position given value, the q-axis pitch position given value and the real-time impeller azimuth angle through inverse Park transformation from the dq stationary coordinate system to the rotating coordinate system, so as to obtain the respective blade angle compensation values ​​of the three blades under IPC control, and then superimpose the respective blade angle compensation values ​​calculated by the IPC control of the three blades on the unified pitch blade angle given value of the wind turbine, so as to obtain the respective blade real-time angle given values ​​of the three blades, that is, the pitch position given values ​​of the three blades; The sending module is used to send the pitch position set values ​​of the three blades to the pitch actuators of the respective blades for execution, so as to realize the IPC control function, thereby achieving the purpose of attenuating the second-order natural frequency vibration in the front-to-back direction of the tower and reducing the second-order natural frequency load in the front-to-back direction of the tower; The specific calculation of the pitch position given values ​​of the three blades is as follows: Where β1, β2, and β3 are the pitch position given values ​​of blade 1, blade 2, and blade 3 respectively; is the real-time impeller azimuth angle of the wind turbine in grid-connected power generation mode; β d , β q are the given values ​​of the d-axis and q-axis pitch positions in the dq stationary coordinate system respectively; β c is a given value for the uniform pitch blade angle; The transfer function of the notch filter is: Where s is a complex variable, ξ1 and ξ2 are the damping ratios of the notch filter, and ω1 and ω2 are the frequencies of the notch filter; The transfer function of the bandpass filter is: Where G is the bandpass filter gain, ξ3 is the bandpass filter damping ratio, ω3 is the bandpass filter frequency, and τ is the bandpass filter time constant.

5. The system for attenuating the second-order vibration and load in the front-to-rear direction of the wind turbine tower according to claim 4, characterized in that: The uniform variable pitch blade angle given value is calculated by the generator speed VS variable pitch position proportional integral PI controller.

6. The system for attenuating the second-order vibration and load in the front-to-rear direction of the wind turbine tower according to claim 4, characterized in that: The acceleration signal in the front-rear direction of the nacelle is provided by a vibration sensor installed inside the nacelle; the real-time impeller azimuth angle is provided by an absolute value rotary encoder installed in the wheel hub.

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