Floating wind turbine speed tracking control above rated wind speed method and system

Abstract

This invention provides a method and system for tracking and controlling the rotational speed of a floating wind turbine above its rated wind speed, relating to the field of wind power generation technology. The method includes: acquiring the gearbox ratio, rated electromagnetic torque, rotor speed, floating foundation pitch velocity, and inflow wind speed of the wind turbine; calculating the electromagnetic torque control signal of the wind turbine using a first electromagnetic torque formula based on the gearbox ratio, rated electromagnetic torque, rotor speed, floating foundation pitch velocity, and inflow wind speed; and sending this signal to the wind turbine controller to eliminate limit loops, control the electromagnetic torque of the wind turbine, and thus maintain a constant rotor speed. This invention creatively proposes to eliminate limit loops by adjusting the electromagnetic torque of the wind turbine, solving the problem of large-scale rotational speed oscillations and maintaining a constant rotor speed. This can effectively improve the rotor speed control effect and indirectly improve the economic benefits of wind power generation.

Description

Technical Field

[0001] This invention relates to the field of wind power generation technology, and in particular to a method and system for tracking the rotational speed of a floating wind turbine above its rated wind speed. Background Technology

[0002] Due to technological and cost limitations, the primary utilization of wind energy currently comes from onshore and near-shore wind turbines with fixed foundations. However, with the planning of offshore wind turbines, the vast and stable deep-sea areas have become the main region for future wind power development. Floating offshore wind turbines are the best choice for utilizing wind energy. However, when floating wind turbines operate in areas with wind speeds higher than their rated speed, large fluctuations in rotor speed are frequently observed. This phenomenon severely affects the power output of the floating turbine and greatly increases mechanical fatigue, potentially even damaging the generator.

[0003] To prevent speed oscillations in floating wind turbines operating above rated wind speed, a common industry practice is to reduce the gain of the speed controller. However, this strategy does not fundamentally solve the problem, as a low-gain controller cannot respond quickly to changes in wind speed and will still result in speed overshoot.

[0004] Existing research suggests that the oscillation problem of the wind turbine's rotational speed may be caused by a limiting cycle. However, research on eliminating the limiting cycle through control strategies to achieve effective speed tracking remains lacking. Summary of the Invention

[0005] In view of the above problems, the present invention proposes a speed tracking control method and a speed tracking control system for floating wind turbines above the rated wind speed.

[0006] This invention provides a method for tracking and controlling the rotational speed of a floating wind turbine above its rated wind speed. The method includes:

[0007] Obtain the gearbox ratio and rated electromagnetic torque of the wind turbine;

[0008] Obtain the rotor speed of the wind turbine;

[0009] Obtain the pitch angular velocity of the floating foundation of the wind turbine;

[0010] Obtain the inflow wind speed of the wind turbine;

[0011] Based on the gearbox ratio, the rated electromagnetic torque, the wind turbine speed, the pitch angular velocity of the floating foundation, and the inflow wind speed, the electromagnetic torque control signal of the wind turbine is calculated using the first electromagnetic torque formula.

[0012] The electromagnetic torque control signal is sent to the wind turbine controller to eliminate the limit loop, control the electromagnetic torque of the wind turbine, and thus control the wind turbine rotor speed to be constant.

[0013] The first electromagnetic torque formula is:

[0014]

[0015]

[0016]

[0017]

[0018] In the above formula: T e It is the electromagnetic torque corresponding to the electromagnetic torque control signal, C q It is the aerodynamic torque coefficient, N Gear It's the gearbox ratio. It is the rated electromagnetic torque, Ω r V is the rotor speed, v0 is the inflow wind speed, β is the blade pitch angle, ρ is the air density, R is the impeller radius, and L is the rotor speed. T It is the height of the tower, v rel It is relative wind speed. It is the pitch angular velocity of the floating foundation.

[0019] Optionally, obtaining the wind turbine rotor speed includes:

[0020] The measurement signal is obtained by measuring the wind turbine rotation speed;

[0021] The wind turbine rotation speed is obtained by filtering the measured signal through a low-pass filter.

[0022] Optionally, obtaining the inflow wind speed of the wind turbine includes:

[0023] The effective wind speed measurement value of the wind turbine is obtained through wind measurement equipment;

[0024] The effective wind speed measurement value is used as the inflow wind speed.

[0025] Optionally, the measurement signal is filtered by a low-pass filter, including:

[0026] The measurement signal is passed through a cutoff frequency of... The low-pass filter is used for filtering, where, It is the rated rotor speed.

[0027] Optionally, the speed tracking control method further includes:

[0028] Calculate the aerodynamic torque compensation value;

[0029] Based on the aerodynamic torque compensation value and the gearbox ratio, the electromagnetic torque control signal of the wind turbine is calculated using the second electromagnetic torque formula.

[0030] The second electromagnetic torque formula is as follows:

[0031]

[0032] In the above formula, T a,comp This is the aerodynamic torque compensation value.

[0033] Optionally, the aerodynamic torque compensation value is calculated, including:

[0034] The aerodynamic torque of the wind turbine is decomposed according to the square of the relative wind speed in its expression, resulting in the aerodynamic torque T. a Expanded to: Right now:

[0035]

[0036] Based on T a,cross and The aerodynamic torque compensation value is obtained by calculating the respective expressions.

[0037] Alternatively, neglecting losses, since P a =P e =N Gear Ω r T e Substituting the first electromagnetic torque formula into the equation yields the following:

[0038]

[0039] In the above formula, P a It is the aerodynamic power of the wind turbine unit. P is the rated aerodynamic power of the wind turbine generator set. e It is electromagnetic power;

[0040] Substituting the above formula into the model formula of the floating wind turbine above the rated wind speed, considering the two degrees of freedom of rotor rotation and floating foundation pitch, and using the Bendickson criterion to determine that the Bendickson discriminant function is always negative in the domain, that is, the limit cycle does not exist, so that the limit cycle is eliminated when the wind turbine is controlled by the electromagnetic torque control signal.

[0041] The model formula is as follows:

[0042]

[0043]

[0044] In the above two equations, J is the moment of inertia of the wind turbine, and I... Mass It is the moment of inertia of the floating foundation during pitching, M HS It is the restoring torque in still water, M rad It is the hydrodynamic radiation torque, M diff It is the hydrodynamic diffraction moment, F a It is aerodynamic thrust.

[0045] Optionally, the speed tracking control method further includes:

[0046] Based on the rated wind turbine speed and the wind turbine speed, a speed control signal is calculated;

[0047] The wind turbine speed is controlled according to the speed control signal.

[0048] Optionally, based on the rated rotor speed and the rotor speed, a speed control signal is calculated, including:

[0049] Calculate the difference between the rated wind turbine speed and the wind turbine speed;

[0050] The difference is used as the speed control signal.

[0051] This invention provides a speed tracking control system for a floating wind turbine above its rated wind speed, the speed tracking control system comprising:

[0052] The basic parameter module is used to obtain the gearbox ratio and rated electromagnetic torque of the wind turbine.

[0053] The speed module is used to obtain the rotor speed of the wind turbine.

[0054] The pitch rate module is used to obtain the pitch rate of the floating foundation of the wind turbine.

[0055] The inflow wind speed module is used to obtain the inflow wind speed of the wind turbine.

[0056] The electromagnetic torque calculation module is used to calculate the electromagnetic torque control signal of the wind turbine unit based on the gearbox ratio, the rated electromagnetic torque, the wind turbine speed, the pitch angular velocity of the floating foundation, and the inflow wind speed, using the first electromagnetic torque formula.

[0057] The electromagnetic torque control module is used to send the electromagnetic torque control signal to the wind turbine controller to eliminate limit loops, control the electromagnetic torque of the wind turbine, and thus control the wind turbine rotor speed to be constant.

[0058] The first electromagnetic torque formula is:

[0059]

[0060]

[0061]

[0062]

[0063] In the above formula: T e It is the electromagnetic torque corresponding to the electromagnetic torque control signal, C q It is the aerodynamic torque coefficient, N Gear It's the gearbox ratio. It is the rated electromagnetic torque, Ω r V is the rotor speed, v0 is the inflow wind speed, β is the blade pitch angle, ρ is the air density, R is the impeller radius, and L is the rotor speed. T It is the height of the tower, v rel It is relative wind speed. It is the pitch angular velocity of the floating foundation.

[0064] Optionally, the rotation speed module includes:

[0065] The measurement unit is used to measure the wind turbine rotation speed and obtain measurement signals.

[0066] The filtering unit is used to filter the measurement signal through a low-pass filter to obtain the wind turbine speed.

[0067] Optionally, the inflow velocity module is specifically used for:

[0068] The effective wind speed measurement value of the wind turbine is obtained through wind measurement equipment;

[0069] The effective wind speed measurement value is used as the inflow wind speed.

[0070] Optionally, the filtering unit is specifically used for:

[0071] The measurement signal is passed through a cutoff frequency of... The low-pass filter is used for filtering, where, It is the rated rotor speed.

[0072] Optionally, the speed tracking control system further includes:

[0073] The pneumatic torque compensation module is used to calculate the pneumatic torque compensation value.

[0074] The torque calculation module is used to calculate the electromagnetic torque control signal of the wind turbine based on the aerodynamic torque compensation value and the gearbox ratio, using the second electromagnetic torque formula.

[0075] The second electromagnetic torque formula is as follows:

[0076]

[0077] In the above formula, T a,comp This is the aerodynamic torque compensation value.

[0078] Optionally, the pneumatic torque compensation module is specifically used for:

[0079] The aerodynamic torque of the wind turbine is decomposed according to the square of the relative wind speed in its expression, resulting in the aerodynamic torque T. a Expanded to: Right now:

[0080]

[0081] Based on T a,cross and The aerodynamic torque compensation value is obtained by calculating the respective expressions.

[0082] Neglecting losses, since P a =P e =N Gear Ω r T e Substituting the first electromagnetic torque formula into the equation yields the following:

[0083]

[0084] In the above formula, P a It is the aerodynamic power of the wind turbine unit. P is the rated aerodynamic power of the wind turbine generator set. e It is electromagnetic power;

[0085] Substituting the above formula into the model formula of the floating wind turbine above the rated wind speed, considering the two degrees of freedom of rotor rotation and floating foundation pitch, and using the Bendickson criterion to determine that the Bendickson discriminant function is always negative in the domain, that is, the limit cycle does not exist, so that the limit cycle is eliminated when the wind turbine is controlled by the electromagnetic torque control signal.

[0086] The model formula is as follows:

[0087]

[0088]

[0089] In the above two equations, J is the moment of inertia of the wind turbine, and I... MassIt is the moment of inertia of the floating foundation during pitching, M HS It is the restoring torque in still water, M rad It is the hydrodynamic radiation torque, M diff It is the hydrodynamic diffraction moment, F a It is aerodynamic thrust.

[0090] Optionally, the speed tracking control system further includes:

[0091] The speed calculation module is used to calculate the speed control signal based on the rated wind turbine speed and the wind turbine speed;

[0092] The speed control module is used to control the wind turbine speed according to the speed control signal.

[0093] Optionally, the speed calculation module is specifically used for:

[0094] Calculate the difference between the rated wind turbine speed and the wind turbine speed;

[0095] The difference is used as the speed control signal.

[0096] The floating wind turbine's speed tracking control method above rated wind speed provided by this invention first obtains the gearbox ratio and rated electromagnetic torque of the wind turbine; then obtains the wind turbine's rotor speed; finally obtains the pitch angular velocity of the floating foundation of the wind turbine; and finally obtains the inflow wind speed of the wind turbine.

[0097] Based on the gearbox ratio, rated electromagnetic torque, rotor speed, floating foundation pitch angular velocity, and inflow wind speed, the electromagnetic torque control signal of the wind turbine is calculated using the first electromagnetic torque formula. Finally, the electromagnetic torque control signal is sent to the wind turbine controller to eliminate limit loops, control the electromagnetic torque of the wind turbine, and thus control the rotor speed of the wind turbine to remain constant.

[0098] The floating wind turbine speed tracking control method proposed in this invention creatively eliminates the limiting loop in the speed control system by adjusting the electromagnetic torque of the wind turbine, thus solving the problem of large speed oscillations and controlling the wind turbine rotor speed to be constant. This helps reduce the operation and maintenance costs of wind turbines and extend their service life. When the wind turbine operates above the rated wind speed, that is, in the entire high wind speed operating range, it can effectively improve the rotor speed control effect, indirectly improving the economic benefits of wind power generation.

[0099] Furthermore, the speed tracking control method proposed in this invention does not require any changes to the mechanical structure of the wind turbine itself or the pitch angle controller; only the original electromagnetic torque control method needs to be modified, thus offering excellent economic benefits. Since only the original electromagnetic torque control method needs to be changed, only a single nonlinear controller is required to achieve effective control over the entire high-wind-speed operating range, making the controller design simpler and more efficient. Moreover, the proposed speed tracking control method exhibits good dynamic performance, and its speed regulation control effect is significantly superior to the traditional reduced-gain GSPI control method, demonstrating high practicality. Attached Figure Description

[0100] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0101] Figure 1 This is a flowchart of a method for tracking and controlling the rotational speed of a floating wind turbine above its rated wind speed, according to an embodiment of the present invention.

[0102] Figure 2 This is a control block diagram of the speed tracking control method for floating wind turbines above the rated wind speed in an embodiment of the present invention;

[0103] Figure 3 This is a block diagram of a floating wind turbine speed tracking control system above the rated wind speed according to an embodiment of the present invention. Detailed Implementation

[0104] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention, and are only some, not all, embodiments of the present invention, and are not intended to limit the present invention.

[0105] The inventors discovered that, in order to prevent speed oscillations in floating wind turbines above the rated wind speed, the common industry practice is to reduce the gain of the speed controller to avoid this problem.

[0106] However, this strategy does not fundamentally solve the problem because a low-gain controller cannot respond quickly to changes in wind speed, still resulting in rotor speed overshoot. Current research suggests that the rotor speed oscillation issue may be caused by a limiting cycle.

[0107] However, research on achieving effective speed tracking by eliminating limit cycles through control strategies remains largely unexplored. How to eliminate limit cycles is a problem that urgently needs to be solved.

[0108] The inventors delved into the root cause of speed oscillations caused by limiting cycles in floating wind turbines, conducted corresponding analyses, and, after extensive research, creatively proposed a control improvement strategy based on electromagnetic torque compensation, thereby eliminating limiting cycles.

[0109] First, the inventors discovered that the current model for the speed control system of floating wind turbines above rated wind speed, considering the two degrees of freedom of rotor rotation and the pitching of the floating foundation, can be expressed by the following two formulas:

[0110]

[0111]

[0112] In the above two equations, J is the moment of inertia of the wind turbine, and Ω r v0 is the rotor speed, and v0 is the inflow wind speed. β is the pitch angle of the floating base, N is the pitch angle of the propeller, and N is the pitch angle of the base. Gear It's the gearbox ratio, T e It is electromagnetic torque, T a It is aerodynamic torque, I Mass It is the moment of inertia of the floating foundation during pitching, L T It is the height of the tower, M HS It is the restoring torque in still water, M rad It is the hydrodynamic radiation torque, M diff It is the hydrodynamic diffraction moment, F a It is aerodynamic thrust.

[0113] The expressions for the aerodynamic power, aerodynamic torque, and aerodynamic thrust of a floating wind turbine are shown in the three equations on the three sides:

[0114]

[0115]

[0116]

[0117] In the above three equations, P a T represents aerodynamic power. a F represents aerodynamic torque. a This represents aerodynamic thrust, where ρ is air density and R is impeller radius. It is the relative wind speed, λ is the tip speed ratio, and λ is defined as:

[0118]

[0119] And C p C q and C t These are the aerodynamic power coefficient, aerodynamic torque coefficient, and aerodynamic thrust coefficient, which satisfy the following relationship:

[0120]

[0121] Based on the above theory and various expressions, the inventors discovered that the limiting cycle of the floating wind turbine generator is caused by pitching motion. Substituting equation (4) into (1), we get the following equation:

[0122]

[0123] Next, by breaking down the aerodynamic torque according to the square of the relative wind speed in its expression, the aerodynamic torque can be expanded as follows: This yields the following formula:

[0124]

[0125] Based on the above equation (9), the inventors creatively added the two parts containing the square term of the floating foundation pitch angular velocity and the cross term to the electromagnetic torque control signal T. e In the middle, let the electromagnetic torque control signal T e for:

[0126]

[0127] Neglecting losses, we can obtain P a =P e =N Gear Ω r T e Substituting equation (10) into the equation, we obtain the following equation:

[0128]

[0129] In the above formula, P a It refers to the aerodynamic power of the wind turbine. It is the rated aerodynamic power of the wind turbine, P e It is electromagnetic power.

[0130] Substituting equation (11) into equations (1) and (2) above and using the Bendickson criterion for judgment, it is found that the Bendickson discriminant function is always negative in the domain, that is, there is no limit cycle. This indicates that the electromagnetic torque compensation strategy can eliminate the limit cycle.

[0131] Based on the above-mentioned inventive findings, this invention proposes a method for tracking and controlling the rotational speed of a floating wind turbine above its rated wind speed, referring to... Figure 1As shown, the speed tracking control method includes:

[0132] Step 101: Obtain the gearbox ratio and rated electromagnetic torque of the wind turbine.

[0133] First, obtain the gearbox ratio and rated electromagnetic torque of the floating wind turbine. Generally, the gearbox ratio and rated electromagnetic torque are fixed values ​​after the wind turbine is manufactured and put into operation, and will not change.

[0134] Step 102: Obtain the wind turbine rotation speed.

[0135] Secondly, it is necessary to obtain the rotor speed of the floating wind turbine. Generally, the rotor speed is not a constant value but may vary depending on the actual application. A preferred method for obtaining the rotor speed includes:

[0136] The wind turbine rotational speed is measured to obtain a measurement signal. This signal is then filtered through a low-pass filter to obtain the wind turbine rotational speed. For low-pass filtering, the measurement signal can be filtered through a filter with a cutoff frequency of... The low-pass filter is used for filtering, in which, This refers to the rated rotor speed. Generally, the rated rotor speed is a constant value after the wind turbine is manufactured and put into operation, and it will not change. Therefore, the cutoff frequency of the low-pass filter is also a constant value, thus allowing for a precise determination of the rotor speed.

[0137] Step 103: Obtain the pitch angular velocity of the floating foundation of the wind turbine.

[0138] Step 104: Obtain the inflow wind speed of the wind turbine.

[0139] Based on the foregoing analysis, it is also necessary to obtain the pitch angular velocity of the floating foundation and the inflow wind speed of the floating wind turbine. One preferred method for obtaining the inflow wind speed includes:

[0140] The effective wind speed of the wind turbine is obtained by using wind measuring equipment, such as lidar or wind cups; this effective wind speed measurement is then used as the inflow wind speed.

[0141] Step 105: Based on the gearbox ratio, rated electromagnetic torque, rated wind turbine speed, wind turbine speed, floating foundation pitch angular velocity, and inflow wind speed, calculate the electromagnetic torque control signal of the wind turbine using the first electromagnetic torque formula.

[0142] After obtaining the above parameters, an electromagnetic torque can be calculated using the first electromagnetic torque formula based on the gearbox ratio, rated electromagnetic torque, rated wind turbine speed, wind turbine speed, floating foundation pitch angular velocity, and inflow wind speed. This electromagnetic torque can then be used to generate an electromagnetic torque control signal for the wind turbine unit.

[0143] The formula for the first electromagnetic torque is:

[0144]

[0145]

[0146]

[0147]

[0148] In the above formula: T e It is the electromagnetic torque corresponding to the electromagnetic torque control signal, C. q It is the aerodynamic torque coefficient, N Gear It's the gearbox ratio. It is the rated electromagnetic torque, Ω r V is the rotor speed, v0 is the inflow wind speed, β is the blade pitch angle, ρ is the air density, R is the impeller radius, and L is the rotor speed. T It is the height of the tower, v rel q is the relative wind speed, and q is the pitch angular velocity of the floating foundation.

[0149] Furthermore, based on the aforementioned analysis and equation (9), it can be seen that the electromagnetic torque control signal can also be obtained based on the aerodynamic torque compensation value. First, the aerodynamic torque compensation value is calculated; then, based on the aerodynamic torque compensation value and the gearbox ratio, the electromagnetic torque can be calculated using the second electromagnetic torque formula, thereby generating the electromagnetic torque control signal for the wind turbine.

[0150] The formula for the second electromagnetic torque is:

[0151]

[0152] In the above formula, T a,comp This refers to the aerodynamic torque compensation value. The specific methods for calculating the aerodynamic torque compensation value include:

[0153] If we decompose the aerodynamic torque of the wind turbine according to the square of the relative wind speed in its expression, then the aerodynamic torque T is obtained. a Expanded to: Right now:

[0154]

[0155] Based on T a,cross and The aerodynamic torque compensation value is obtained by calculating the respective expressions.

[0156] Electromagnetic torque can be obtained through the above methods, and electromagnetic torque can eliminate limit cycles.

[0157] Step 106: Send the electromagnetic torque control signal to the wind turbine controller to eliminate the limit loop, control the electromagnetic torque of the wind turbine, and thus control the wind turbine rotor speed to be constant.

[0158] After obtaining the electromagnetic torque control signal, the signal is sent to the wind turbine controller to eliminate the limit loop, control the electromagnetic torque of the wind turbine, and thus keep the rotor speed of the wind turbine constant.

[0159] For specific wind turbine speed control, one approach is to calculate the speed control signal based on the rated wind turbine speed and the actual wind turbine speed; then, control the wind turbine speed according to the speed control signal. A more efficient approach is to calculate the difference between the rated wind turbine speed and the actual wind turbine speed; use this difference as the speed control signal to control the wind turbine speed and keep it constant.

[0160] The speed tracking control method for floating wind turbines above rated wind speed proposed in this invention can be based on... Figure 2 The control block diagram shown provides a more intuitive understanding. Figure 2 The example shown is a blade pitch controller used to control the speed of a wind turbine. This does not mean that the method proposed in this invention is only applicable to speed control systems where the blade pitch controller is used to control the speed of a wind turbine. Any type of controller that can control the speed of a wind turbine can be used as an alternative.

[0161] Figure 2 The calculation of the aerodynamic torque compensation value T is shown. a,comp Thus, the electromagnetic torque T is obtained. e Based on this electromagnetic torque, the wind turbine can eliminate the limiting cycle, enabling the blade pitch controller to maintain a constant rotor speed.

[0162] To demonstrate the control effectiveness of the proposed speed tracking control method for floating wind turbines above rated wind speed, a 5MW ITI Barge floating wind turbine was used as an example for testing. The process involved is as follows:

[0163] 1) Obtain the aerodynamic torque characteristic function of the wind turbine. Gearbox ratio Rated electromagnetic torque Rated wind turbine speed Where: Ω r β is the measured value of the wind turbine rotation speed, β is the measured value of the blade pitch angle, and v0 is the measured value of the effective wind speed of the wind turbine. The measured value of the pitch angular velocity of the floating foundation;

[0164] 2) The wind turbine speed is measured using an encoder, and the speed is passed through a cutoff frequency of [frequency value missing]. The wind turbine speed measurement value is obtained after passing through a low-pass filter;

[0165] 3) The pitch angular velocity of the floating foundation is measured using a velocity sensor;

[0166] 4) Obtain the effective wind speed measurement value of the wind turbine using a wind speed measuring device;

[0167] 5) Calculate the electromagnetic torque control signal based on the aforementioned electromagnetic torque formula;

[0168] 6) Input the obtained electromagnetic torque control signal to the floating wind turbine controller.

[0169] The proposed method was simulated and verified using the dynamic simulation software OpenFAST. The operating range of a 5MW wind turbine in the high wind speed area is 11.4m / s-25m / s. To evaluate the control performance of the proposed method in the entire high wind speed operating range, simulation tests were conducted under the following typical wind conditions: average wind speed 18m / s, turbulence intensity 10%; irregular wave height 1.265m, period 7.5s.

[0170] To evaluate the control performance of the method proposed in this invention, the commonly used gain-scheduled proportional-integral (GSPI) control method and the detuned GSPI (D-GSPI) control method are used as benchmarks. The control performance of this invention combined with the GSPI method is compared and analyzed.

[0171] The control performance index considered is the root mean square error of the wind turbine speed. The following table shows a comparison of the control performance of the proposed method with traditional GSPI and D-GSPI control methods under typical wind conditions:

[0172] controller Mean square error of rotational speed (rpm) D-GSPI 0.4458 GSPI 1.7233 GSPI+ The method proposed in this invention 0.1706

[0173] In the table above, the root mean square error of the rotational speed represents the root mean square error of the wind turbine rotational speed. It can be seen that, throughout the entire high wind speed operating range, the rotational speed tracking control method for floating wind turbines proposed in this invention above the rated wind speed can effectively improve the wind turbine rotational speed control performance.

[0174] Based on the above-mentioned speed tracking control method for floating wind turbines above the rated wind speed, this invention also proposes a speed tracking control system for floating wind turbines above the rated wind speed, referring to... Figure 3 The block diagram shown indicates that the speed tracking control system includes:

[0175] Basic parameter module 310 is used to obtain the gearbox ratio and rated electromagnetic torque of the wind turbine.

[0176] The speed module 320 is used to obtain the wind turbine rotation speed of the wind turbine unit;

[0177] The pitch rate module 330 is used to obtain the pitch rate of the floating foundation of the wind turbine.

[0178] Inflow velocity module 340 is used to acquire the inflow velocity of the wind turbine unit;

[0179] The electromagnetic torque calculation module 350 is used to calculate the electromagnetic torque control signal of the wind turbine unit based on the gearbox ratio, the rated electromagnetic torque, the wind turbine speed, the pitch angular velocity of the floating foundation, and the inflow wind speed, using the first electromagnetic torque formula.

[0180] The electromagnetic torque control module 360 ​​is used to send the electromagnetic torque control signal to the wind turbine controller to eliminate limit loops, control the electromagnetic torque of the wind turbine, and thus control the wind turbine rotor speed of the wind turbine to be constant.

[0181] The first electromagnetic torque formula is:

[0182]

[0183]

[0184]

[0185]

[0186] In the above formula: T e It is the electromagnetic torque corresponding to the electromagnetic torque control signal, C q It is the aerodynamic torque coefficient, N Gear It's the gearbox ratio. It is the rated electromagnetic torque, Ω r V is the rotor speed, v0 is the inflow wind speed, β is the blade pitch angle, ρ is the air density, R is the impeller radius, and L is the rotor speed. T It is the height of the tower, v rel It is relative wind speed. It is the pitch angular velocity of the floating foundation.

[0187] Optionally, the rotation speed module 320 includes:

[0188] The measurement unit is used to measure the wind turbine rotation speed and obtain measurement signals.

[0189] The filtering unit is used to filter the measurement signal through a low-pass filter to obtain the wind turbine speed.

[0190] Optionally, the inflow velocity module 340 is specifically used for:

[0191] The effective wind speed measurement value of the wind turbine is obtained through wind measurement equipment;

[0192] The effective wind speed measurement value is used as the inflow wind speed.

[0193] Optionally, the filtering unit is specifically used for:

[0194] The measurement signal is passed through a cutoff frequency of... The low-pass filter is used for filtering, where, It is the rated rotor speed.

[0195] Optionally, the speed tracking control system further includes:

[0196] The pneumatic torque compensation module is used to calculate the pneumatic torque compensation value.

[0197] The torque calculation module is used to calculate the electromagnetic torque control signal of the wind turbine based on the aerodynamic torque compensation value and the gearbox ratio, using the second electromagnetic torque formula.

[0198] The second electromagnetic torque formula is as follows:

[0199]

[0200] In the above formula, T a,comp This is the aerodynamic torque compensation value.

[0201] Optionally, the pneumatic torque compensation module is specifically used for:

[0202] The aerodynamic torque of the wind turbine is decomposed according to the square of the relative wind speed in its expression, resulting in the aerodynamic torque T. a Expanded to: Right now:

[0203]

[0204] Based on T a,cross and The aerodynamic torque compensation value is obtained by calculating the respective expressions.

[0205] Neglecting losses, since P a =P e =N Gear Ω r T e Substituting the first electromagnetic torque formula into the equation yields the following:

[0206]

[0207] In the above formula, Pa It is the aerodynamic power of the wind turbine unit. P is the rated aerodynamic power of the wind turbine generator set. e It is electromagnetic power;

[0208] Substituting the above formula into the model formula of the floating wind turbine above the rated wind speed, considering the two degrees of freedom of rotor rotation and floating foundation pitch, and using the Bendickson criterion to determine that the Bendickson discriminant function is always negative in the domain, that is, the limit cycle does not exist, so that the limit cycle is eliminated when the wind turbine is controlled by the electromagnetic torque control signal.

[0209] The model formula is as follows:

[0210]

[0211]

[0212] In the above two equations, J is the moment of inertia of the wind turbine, and I... Mass It is the moment of inertia of the floating foundation during pitching, M HS It is the restoring torque in still water, M rad It is the hydrodynamic radiation torque, M diff It is the hydrodynamic diffraction moment, F a It is aerodynamic thrust.

[0213] Optionally, the speed tracking control system further includes:

[0214] The speed calculation module is used to calculate the speed control signal based on the rated wind turbine speed and the wind turbine speed;

[0215] The speed control module is used to control the wind turbine speed according to the speed control signal.

[0216] Optionally, the speed calculation module is specifically used for:

[0217] Calculate the difference between the rated wind turbine speed and the wind turbine speed;

[0218] The difference is used as the speed control signal.

[0219] In summary, the floating wind turbine speed tracking control method of the present invention first obtains the gearbox ratio and rated electromagnetic torque of the wind turbine; then obtains the rotor speed of the wind turbine; finally obtains the pitch angular velocity of the floating foundation of the wind turbine; and finally obtains the inflow wind speed of the wind turbine.

[0220] Based on the gearbox ratio, rated electromagnetic torque, rotor speed, floating foundation pitch angular velocity, and inflow wind speed, the electromagnetic torque control signal of the wind turbine is calculated using the first electromagnetic torque formula. Finally, the electromagnetic torque control signal is sent to the wind turbine controller to eliminate limit loops, control the electromagnetic torque of the wind turbine, and thus control the rotor speed of the wind turbine to remain constant.

[0221] The floating wind turbine speed tracking control method proposed in this invention creatively eliminates the limiting loop in the speed control system by adjusting the electromagnetic torque of the wind turbine, thus solving the problem of large speed oscillations and controlling the wind turbine rotor speed to be constant. This helps reduce the operation and maintenance costs of wind turbines and extend their service life. When the wind turbine operates above the rated wind speed, that is, in the entire high wind speed operating range, it can effectively improve the rotor speed control effect, indirectly improving the economic benefits of wind power generation.

[0222] Furthermore, the speed tracking control method proposed in this invention does not require any changes to the mechanical structure of the wind turbine itself or the pitch angle controller; only the original electromagnetic torque control method needs to be modified, thus offering excellent economic benefits. Since only the original electromagnetic torque control method needs to be changed, only a single nonlinear controller is required to achieve effective control over the entire high-wind-speed operating range, making the controller design simpler and more efficient. Moreover, the proposed speed tracking control method exhibits good dynamic performance, and its speed regulation control effect is significantly superior to the traditional reduced-gain GSPI control method, demonstrating high practicality.

[0223] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present invention.

[0224] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes said element.

[0225] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A method for tracking and controlling the rotational speed of a floating wind turbine above its rated wind speed, characterized in that, The speed tracking control method includes: Obtain the gearbox ratio and rated electromagnetic torque of the wind turbine; Obtain the rotor speed of the wind turbine; Obtain the pitch angular velocity of the floating foundation of the wind turbine; Obtain the inflow wind speed of the wind turbine; Based on the gearbox ratio, the rated electromagnetic torque, the wind turbine speed, the pitch angular velocity of the floating foundation, and the inflow wind speed, the electromagnetic torque control signal of the wind turbine is calculated using the first electromagnetic torque formula. The electromagnetic torque control signal is sent to the wind turbine controller to eliminate the limit loop, control the electromagnetic torque of the wind turbine, and thus control the wind turbine rotor speed to be constant. The first electromagnetic torque formula is: In the above formula: It is the electromagnetic torque corresponding to the electromagnetic torque control signal. It is the aerodynamic torque coefficient. It's the gearbox ratio. It is the rated electromagnetic torque. It is the wind turbine speed. It is the inflow wind speed. It is the propeller pitch angle. It is air density. It is the impeller radius. It is the height of the tower. It is relative wind speed. It is the pitch angular velocity of the floating foundation.

2. The speed tracking control method according to claim 1, characterized in that, Obtaining the rotor speed of the wind turbine includes: The measurement signal is obtained by measuring the wind turbine rotation speed; The wind turbine rotation speed is obtained by filtering the measured signal through a low-pass filter.

3. The speed tracking control method according to claim 1, characterized in that, Obtaining the inflow wind speed of the wind turbine includes: The effective wind speed measurement value of the wind turbine is obtained through wind measurement equipment; The effective wind speed measurement value is used as the inflow wind speed.

4. The speed tracking control method according to claim 2, characterized in that, The measurement signal is filtered by a low-pass filter, including: The measurement signal is passed through a cutoff frequency of... The low-pass filter is used for filtering, where, It is the rated rotor speed.

5. The speed tracking control method according to claim 1, characterized in that, The speed tracking control method further includes: Calculate the aerodynamic torque compensation value; Based on the aerodynamic torque compensation value and the gearbox ratio, the electromagnetic torque control signal of the wind turbine is calculated using the second electromagnetic torque formula. The second electromagnetic torque formula is as follows: In the above formula, This is the aerodynamic torque compensation value.

6. The speed tracking control method according to claim 5, characterized in that, Calculate the aerodynamic torque compensation value, including: The aerodynamic torque of the wind turbine is decomposed according to the square of the relative wind speed in its expression, and then the aerodynamic torque is obtained. Expanded to: ,Right now: based on and The aerodynamic torque compensation value is obtained by calculating the respective expressions. .

7. The speed tracking control method according to claim 1, characterized in that, Neglecting losses, due to Substituting the first electromagnetic torque formula into the equation yields the following: In the above formula, P a It is the aerodynamic power of the wind turbine unit. It is the rated aerodynamic power of the wind turbine unit. It is electromagnetic power; Substituting the above formula into the model formula of the floating wind turbine above the rated wind speed, considering the two degrees of freedom of rotor rotation and floating foundation pitch, and using the Bendickson criterion to determine that the Bendickson discriminant function is always negative in the domain, that is, the limit cycle does not exist, so that the limit cycle is eliminated when the wind turbine is controlled by the electromagnetic torque control signal. The model formula is as follows: In the above two equations, It is the moment of inertia of the wind turbine. It is the moment of inertia of the floating foundation during pitching. It is the restoring torque of still water. It is the hydrodynamic radiation torque. It is the hydrodynamic diffraction moment. It is aerodynamic thrust.

8. The speed tracking control method according to claim 4, characterized in that, The speed tracking control method further includes: Based on the rated wind turbine speed and the wind turbine speed, a speed control signal is calculated; The wind turbine speed is controlled according to the speed control signal.

9. The speed tracking control method according to claim 8, characterized in that, Based on the rated rotor speed and the rotor speed, a speed control signal is calculated, including: Calculate the difference between the rated wind turbine speed and the wind turbine speed; The difference is used as the speed control signal.

10. A speed tracking control system for a floating wind turbine above its rated wind speed, characterized in that, The speed tracking control system includes: The basic parameter module is used to obtain the gearbox ratio and rated electromagnetic torque of the wind turbine. The speed module is used to obtain the rotor speed of the wind turbine. The pitch rate module is used to obtain the pitch rate of the floating foundation of the wind turbine. The inflow wind speed module is used to obtain the inflow wind speed of the wind turbine. The electromagnetic torque calculation module is used to calculate the electromagnetic torque control signal of the wind turbine unit based on the gearbox ratio, the rated electromagnetic torque, the wind turbine speed, the pitch angular velocity of the floating foundation, and the inflow wind speed, using the first electromagnetic torque formula. The electromagnetic torque control module is used to send the electromagnetic torque control signal to the wind turbine controller to eliminate limit loops, control the electromagnetic torque of the wind turbine, and thus control the wind turbine rotor speed to be constant. The first electromagnetic torque formula is: In the above formula: It is the electromagnetic torque corresponding to the electromagnetic torque control signal. It is the aerodynamic torque coefficient. It's the gearbox ratio. It is the rated electromagnetic torque. It is the wind turbine speed. It is the inflow wind speed. It is the propeller pitch angle. It is air density. It is the impeller radius. It is the height of the tower. It is relative wind speed. It is the pitch angular velocity of the floating foundation.

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