A tower load reduction control method and system for wind turbines based on a linearized model

Abstract

The present invention discloses a method and system for reducing the load of a wind turbine tower based on a linearized model, including: calculating the aerodynamic thrust and aerodynamic torque in the front and rear directions of the wind turbine rotor, the bending moment in the pitch direction of the wind turbine rotor, the equivalent aerodynamic torque of the wind turbine rotor, and the aerodynamic force in the left and right directions of the wind turbine rotor according to the calculated values; establishing a linearized model in the front, rear, left, and right directions of the tower according to the calculated equivalent forces in the front and rear directions and the left and right directions of the tower top, and considering the coupling effect of the deformation in the front and rear and left and right directions of the tower; calculating the pitch command and the generator torque command according to the equivalent forces in the front and rear directions and the left and right directions of the tower top, the speeds in the front and rear directions and the left and right directions of the tower top, and superimposing them onto the pitch control and torque control loops of the unit respectively to actively reduce the tower load. The present invention can achieve optimal control of the tower load and lightweight design of the tower.

Description

Technical Field

[0001] The present invention relates to the technical field of wind turbine control, and in particular to a tower load reduction control method, system, storage medium and computing device for wind turbines based on a linearized model. Background Art

[0002] With the progress of global new energy technologies, wind power generation is developing rapidly towards high efficiency, high reliability, low cost and intelligence, and wind turbines are also moving towards large scale, high tower, lightweight, intelligent and deep sea. The weight of the tower accounts for the main part of the cost of the entire unit. Therefore, at the beginning of the design of wind turbines, some new control technologies and methods need to be adopted to optimize the tower weight of the unit. Conventional tower load reduction control methods, including non-linear pitch control and tower damping control, have limited effects on reducing the fatigue load and ultimate load of the tower. For this reason, a tower load reduction control scheme based on a linearized tower model needs to be proposed. Summary of the Invention

[0003] The first object of the present invention is to overcome the disadvantages and deficiencies of the prior art, and provide a tower load reduction control method for wind turbines based on a linearized model, so as to achieve optimal control of tower loads and lightweight design of the tower.

[0004] The second object of the present invention is to provide a tower load reduction control system for wind turbines based on a linearized model.

[0005] The third object of the present invention is to provide a storage medium.

[0006] The fourth object of the present invention is to provide a computing device.

[0007] The first object of the present invention is achieved by the following technical solutions: A tower load reduction control method for wind turbines based on a linearized model performs the following operations:

[0008] Aerodynamic linearization: including the calculation of the aerodynamic thrust and torque received by the wind turbine, and then according to the calculated aerodynamic thrust and torque, calculating the aerodynamic thrust in the front and rear directions of the wind turbine, the bending moment in the pitch direction of the wind turbine, the equivalent aerodynamic torque of the wind turbine and the aerodynamic force in the left and right directions of the wind turbine;

[0009] Tower motion linearization: It includes the calculation of the equivalent force in the front-back direction and the equivalent force in the left-right direction at the top of the tower. The equivalent force in the front-back direction at the top of the tower is composed of the aerodynamic thrust in the front-back direction of the wind turbine and the bending moment in the pitch direction of the wind turbine. The equivalent force in the left-right direction at the top of the tower is composed of the equivalent aerodynamic torque of the wind turbine and the aerodynamic force in the left-right direction of the wind turbine. Then, based on the calculated equivalent force in the front-back direction and the equivalent force in the left-right direction at the top of the tower, and considering the coupling effect of the deformation in the front-back and left-right directions of the tower, the contribution of the left-right speed of the tower to the deformation in the front-back direction and the contribution of the front-back speed of the tower to the deformation in the left-right direction are added, and a linearization model in the front-back, left-right directions of the tower is established;

[0010] Tower load reduction control: According to the equivalent force in the front-back direction at the top of the tower, the equivalent force in the left-right direction at the top of the tower, the front-back speed at the top of the tower and the left-right speed of the tower, the pitch command and the generator torque command are calculated, and are respectively superimposed on the pitch control and torque control loops of the unit to actively reduce the tower load.

[0011] Furthermore, when the wind turbine is facing the wind direction and the air flow passes through the wind turbine, the wind turbine will be subjected to aerodynamic thrust and aerodynamic torque. Based on the theory of aerodynamics, the aerodynamic thrust received by the wind turbine is proportional to the air density, the square of the wind turbine radius, the square of the average wind speed and the thrust coefficient, and the aerodynamic torque received by the wind turbine is proportional to the air density, the cube of the wind turbine radius, the square of the average wind speed and the torque coefficient. The specific expressions are as follows:

[0012]

[0013] In the above formula, F a represents the aerodynamic thrust of the wind turbine; T a represents the aerodynamic torque of the wind turbine; ρ represents the air density; π represents the constant of pi; R represents the radius of the wind turbine; v represents the average wind speed; λ is the tip speed ratio; β represents the average blade angle; C t (λ,β) represents the thrust coefficient, which is a function of the tip speed ratio and the average blade angle; C q (λ,β) represents the torque coefficient, which is a function of the tip speed ratio and the average blade angle;

[0014] The aerodynamic thrust of the wind turbine is the sum of the thrusts received by each blade. Due to the influence of wind shear and turbulence on the wind turbine, the thrusts received by each blade are not the same. Considering the thrust received by each blade, the following expression is established:

[0015]

[0016] In the above formula, δF 1，fa represents the additional thrust received by blade 1; δF 2，fa represents the additional thrust received by blade 2; δF 3，fa represents the additional thrust received by blade 3; μ ρ represents the uncertainty of the air density; represents the partial derivative of the aerodynamic thrust of the wind turbine with respect to the pitch angle; δβ1 represents the additional pitch angle of blade 1; δβ2 represents the additional pitch angle of blade 2; δβ3 represents the additional pitch angle of blade 3; represents the partial derivative of the aerodynamic thrust of the wind turbine with respect to the average wind speed; δν1 represents the additional wind speed of blade 1; δν2 represents the additional wind speed of blade 2; δν3 represents the additional wind speed of blade 3;

[0017] The aerodynamic torque of the wind turbine is the sum of the torques received by each blade. Due to the influence of wind direction deviation and turbulence on the wind turbine, the torques received by each blade are not the same. Considering the torques received by each blade, the following expression is established:

[0018]

[0019] In the above formula, δT 1，a represents the additional torque received by blade 1; δT 2，a represents the additional torque received by blade 2; δT 3，a represents the additional torque received by blade 3; μ ρ represents the uncertainty of air density; represents the partial derivative of the aerodynamic torque of the wind turbine with respect to the pitch angle; δβ1 represents the additional pitch angle of blade 1; δβ2 represents the additional pitch angle of blade 2; δβ3 represents the additional pitch angle of blade 3; represents the partial derivative of the aerodynamic torque of the wind turbine with respect to the average wind speed; δv1 represents the additional wind speed of blade 1; δv2 represents the additional wind speed of blade 2; δν3 represents the additional wind speed of blade 3;

[0020] The aerodynamic thrust in the front and rear directions of the wind turbine is the sum of the aerodynamic thrust of the wind turbine and the additional thrust of each blade; the bending moment in the pitching direction of the wind turbine is calculated from the additional thrust of each blade; based on the additional thrust of each blade obtained previously, the aerodynamic thrust in the front and rear directions of the wind turbine and the bending moment in the pitching direction of the wind turbine can be calculated, and the following matrix equation is established:

[0021]

[0022] In the above formula, F fa represents the aerodynamic thrust in the front and rear directions of the wind turbine; M nod represents the bending moment in the pitching direction of the wind turbine; F a represents the aerodynamic thrust of the wind turbine; L b represents the equivalent length of the blade; φ r represents the azimuth angle of the impeller; δνF 1,fa represents the additional thrust received by blade 1; δF 2,fa represents the additional thrust received by blade 2; δF 3,fa represents the additional thrust received by blade 3;

[0023] The equivalent aerodynamic torque of the wind turbine rotor is the sum of the aerodynamic torque of the wind turbine rotor and the additional torque of each blade; the aerodynamic force in the left-right direction of the wind turbine rotor is calculated from the additional torque of each blade; based on the additional torque of each blade obtained previously, the equivalent aerodynamic torque and the aerodynamic force in the left-right direction of the wind turbine rotor can be calculated, and the following matrix equation is established:

[0024]

[0025] In the above formula, T aero represents the equivalent aerodynamic torque of the wind turbine rotor; F ss represents the aerodynamic force in the left-right direction of the wind turbine rotor; T a represents the aerodynamic torque of the wind turbine rotor; L b represents the equivalent length of the blade; φ r represents the azimuth angle of the impeller; δT 1,a represents the additional torque on blade 1; δT 2,a represents the additional torque on blade 2; δT 3,a represents the additional torque on blade 3.

[0026] Furthermore, the tower of the wind turbine is flexible, and the tower will deform in three directions after being stressed. However, the deformation of the tower in the vertical direction is very small compared to the deformation of the tower in the horizontal direction. Therefore, the deformation of the tower in the vertical direction can be ignored, and it is assumed that the deformation of the tower only occurs in two directions in the horizontal plane: the front-back direction of the tower parallel to the wind direction and the left-right direction of the tower perpendicular to the wind direction;

[0027] The equivalent force in the front-back direction at the top of the tower is composed of the aerodynamic thrust in the front-back direction of the wind turbine rotor and the pitching moment of the wind turbine rotor. The equivalent force in the left-right direction at the top of the tower is composed of the aerodynamic force in the left-right direction of the wind turbine rotor and the aerodynamic torque of the wind turbine rotor. The specific definitions are as follows:

[0028]

[0029] In the above formula, F ∑,fa represents the equivalent force in the front-back direction at the top of the tower; F ∑,ss represents the equivalent force in the left-right direction at the top of the tower; F fa represents the aerodynamic thrust in the front-back direction of the wind turbine rotor; K nod2fa represents the equivalent coefficient from the pitching moment to the front-back thrust; M nod represents the pitching moment of the wind turbine rotor; F ss represents the aerodynamic force in the left-right direction of the wind turbine rotor; K a2ss represents the equivalent coefficient from the aerodynamic torque to the left-right aerodynamic force; T aero represents the equivalent aerodynamic torque of the wind turbine rotor;

[0030] The deformation of the tower in the front-back direction can establish the second-order dynamic equation of the tower in the front-back direction, and the deformation of the tower in the left-right direction can establish the second-order dynamic equation of the tower in the left-right direction. However, in order to consider the influence of the single-frequency effect of the wind turbine rotation, i.e., the 1P effect, on the tower vibration during the rotation of the wind turbine, the contribution of the left-right velocity of the tower to the deformation in the front-back direction and the contribution of the front-back velocity of the tower to the deformation in the left-right direction are added. Thus, the coupling effect of the deformation of the tower in the front-back and left-right directions is considered, and a linearized model of the tower in the front-back, left-right directions is established. The matrix equation is as follows:

[0031]

[0032] In the above formula, represents the first derivative of the front-back displacement of the tower top with respect to time; represents the first derivative of the left-right displacement of the tower top with respect to time; represents the first derivative of the front-back velocity of the tower top with respect to time; represents the first derivative of the left-right velocity of the tower top with respect to time; x fa represents the front-back displacement of the tower top; x ss represents the left-right displacement of the tower top; v fa represents the front-back velocity of the tower top; v ss represents the left-right velocity of the tower top; K fa represents the stiffness coefficient in the front-back direction of the tower top; D fa represents the damping coefficient in the front-back direction of the tower top; K ss represents the stiffness coefficient in the left-right direction of the tower top; D ss represents the damping coefficient in the left-right direction of the tower top; N b represents the coupling coefficient between the front-back and left-right directions of the tower; ω r represents the rotational speed of the wind turbine; m t represents the equivalent mass of the tower top; ε m represents the uncertainty of the equivalent mass of the tower top; F ∑,fa represents the equivalent force in the front-back direction of the tower top; F ∑,ss represents the equivalent force in the left-right direction of the tower top.

[0033] Furthermore, the pitch command includes two parts of pitch commands, which are as follows:

[0034] The first part of the pitch command is used to reduce the load in the front-back direction of the tower, and is specifically defined as follows:

[0035]

[0036] In the above formula, represents the first part of the pitch command of blade 1; represents the first part of the pitch command of blade 2; represents the first part of the pitch command of blade 3; C F represents the front-back thrust reduction coefficient; Ffa Indicates the aerodynamic thrust in the front and rear directions of the wind turbine rotor; C v Indicates the damping coefficient added to the front and rear of the tower top; v fa Indicates the speeds in the front and rear directions of the tower top; C M Indicates the pitch moment compensation coefficient; M nod Indicates the moment in the pitch direction of the wind turbine rotor; φ r Indicates the azimuth angle of the impeller; θ f Indicates the phase compensation angle;

[0037] The second part of the pitch command is used to reduce the loads in the left and right directions of the tower. The specific definitions are as follows:

[0038]

[0039] In the above formula, Indicates the second part of the pitch command for blade 1; Indicates the second part of the pitch command for blade 2; Indicates the second part of the pitch command for blade 3; D F Indicates the coefficient for reducing the left and right thrusts; F ss Indicates the aerodynamic force in the left and right directions of the wind turbine rotor; D v Indicates the damping coefficient added to the left and right of the tower top; v ss Indicates the speeds in the left and right directions of the tower top; φ r Indicates the azimuth angle of the impeller; θ s Indicates the phase compensation angle.

[0040] Furthermore, the generator torque command is used to reduce the loads in the left and right directions of the tower. The specific definitions are as follows:

[0041]

[0042] In the above formula, Indicates the generator torque command; E ∑ Indicates the coefficient for reducing the left and right thrusts; F ∑,ss Indicates the equivalent force in the left and right directions of the tower top; E v Indicates the damping coefficient added to the left and right of the tower top; v ss Indicates the speeds in the left and right directions of the tower top.

[0043] The second object of the present invention is achieved by the following technical solution: A wind turbine tower load reduction control system based on a linearized model is used to implement the above-mentioned wind turbine tower load reduction control method based on a linearized model. It includes:

[0044] An aerodynamic linearization module is used to calculate the aerodynamic thrust and aerodynamic torque received by the wind turbine rotor, and then, based on the calculated aerodynamic thrust and aerodynamic torque, calculate the aerodynamic thrust in the front and rear directions of the wind turbine rotor, the moment in the pitch direction of the wind turbine rotor, the equivalent aerodynamic torque of the wind turbine rotor, and the aerodynamic force in the left and right directions of the wind turbine rotor;

[0045] The tower motion linearization module is used to calculate the equivalent forces in the front - rear direction and left - right direction at the top of the tower. Then, based on the calculated equivalent forces in the front - rear direction and left - right direction at the top of the tower, and considering the coupling effect of the deformation in the front - rear and left - right directions of the tower, the contribution of the left - right speed of the tower to the deformation in the front - rear direction and the contribution of the front - rear speed of the tower to the deformation in the left - right direction are increased, and a linearized model of the tower in the front - rear, left - right directions is established.

[0046] The tower load reduction control module calculates the pitch command and the generator torque command according to the equivalent force in the front - rear direction at the top of the tower, the equivalent force in the left - right direction at the top of the tower, the front - rear speed at the top of the tower, and the left - right speed of the tower, and superimposes them on the pitch control and torque control loops of the unit respectively to actively reduce the tower load.

[0047] The third object of the present invention is achieved by the following technical solution: A storage medium stores a program, and when the program is executed by a processor, the above - mentioned wind turbine tower load reduction control method based on a linearized model is realized.

[0048] The fourth object of the present invention is achieved by the following technical solution: A computing device includes a processor and a memory for storing the program executable by the processor. When the processor executes the program stored in the memory, the above - mentioned wind turbine tower load reduction control method based on a linearized model is realized.

[0049] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0050] 1. The present invention proposes a method for linearized modeling of the wind turbine tower motion. The coupling coefficient is introduced in the modeling process to consider the coupling effect of the front - rear and left - right directions of the tower, which more accurately reflects the motion state of the tower.

[0051] 2. Based on the linearization of the tower motion and aerodynamic linearization, the present invention does not require additional sensing and measurement devices, and can directly observe the force condition at the top of the tower and the motion state of the tower, realizing effective monitoring of the state.

[0052] 3. Based on the thrust, bending moment and motion state at the top of the tower, the present invention obtains the pitch command and the generator torque command to actively reduce the tower load. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 It is the architecture diagram of the system of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0054] The present invention will be further described in detail below in conjunction with the embodiments and the drawings, but the embodiments of the present invention are not limited thereto.

[0055] Embodiment 1

[0056] This embodiment discloses a method for reducing the load of a wind turbine tower based on a linearized model, which performs the following operations:

[0057] Aerodynamic linearization: When the wind turbine is facing the wind direction and the air flow passes through the wind turbine, the wind turbine will be subjected to aerodynamic thrust and aerodynamic torque. Based on the theory of aerodynamics, the aerodynamic thrust received by the wind turbine is proportional to the air density, the square of the wind turbine radius, the square of the average wind speed, and the thrust coefficient. The aerodynamic torque received by the wind turbine is proportional to the air density, the cube of the wind turbine radius, the square of the average wind speed, and the torque coefficient. The specific expressions are as follows:

[0058]

[0059] In the above formula, F a represents the aerodynamic thrust of the wind turbine; T a represents the aerodynamic torque of the wind turbine; ρ represents the air density; π represents the constant of the circumference ratio; R represents the radius of the wind turbine; v represents the average wind speed; λ is the tip speed ratio; β represents the average blade angle; C t (λ,β) represents the thrust coefficient, which is a function of the tip speed ratio and the average blade angle; C q (λ,β) represents the torque coefficient, which is a function of the tip speed ratio and the average blade angle;

[0060] The aerodynamic thrust of the wind turbine is the sum of the thrusts received by each blade. Due to the influence of wind shear and turbulence on the wind turbine, the thrust received by each blade is not the same. Considering the thrust received by each blade, the following expression is established:

[0061]

[0062] In the above formula, δF 1,fa represents the additional thrust received by blade 1; δF 2,fa represents the additional thrust received by blade 2; δF 3,fa represents the additional thrust received by blade 3; μ ρ represents the uncertainty of the air density; represents the partial derivative of the aerodynamic thrust of the wind turbine with respect to the pitch angle; δβ1 represents the additional pitch angle of blade 1; δβ2 represents the additional pitch angle of blade 2; δβ3 represents the additional pitch angle of blade 3; represents the partial derivative of the aerodynamic thrust of the wind turbine with respect to the average wind speed; δν1 represents the additional wind speed of blade 1; δν2 represents the additional wind speed of blade 2; δν3 represents the additional wind speed of blade 3;

[0063] The aerodynamic torque of the wind turbine is the sum of the torques received by each blade. Due to the influence of wind direction deviation and turbulence on the wind turbine, the torque received by each blade is not the same. Considering the torque received by each blade, the following expression is established:

[0064]

[0065] In the above formula, δT 1,a represents the additional torque on blade 1; δT 2,a represents the additional torque on blade 2; δT 3,a represents the additional torque on blade 3; μ ρ represents the uncertainty of air density; represents the partial derivative of the aerodynamic torque of the wind turbine with respect to the pitch angle; δβ1 represents the additional pitch angle of blade 1; δβ2 represents the additional pitch angle of blade 2; δβ3 represents the additional pitch angle of blade 3; represents the partial derivative of the aerodynamic torque of the wind turbine with respect to the average wind speed; δv1 represents the additional wind speed of blade 1; δv2 represents the additional wind speed of blade 2; δv3 represents the additional wind speed of blade 3;

[0066] The aerodynamic thrust in the front and rear directions of the wind turbine is the sum of the aerodynamic thrust of the wind turbine and the additional thrust of each blade; the bending moment in the pitch direction of the wind turbine is calculated from the additional thrust of each blade; based on the additional thrust of each blade obtained above, the aerodynamic thrust in the front and rear directions of the wind turbine and the bending moment in the pitch direction of the wind turbine can be calculated, and the following matrix equation is established:

[0067]

[0068] In the above formula, F fa represents the aerodynamic thrust in the front and rear directions of the wind turbine; M nod represents the bending moment in the pitch direction of the wind turbine; F a represents the aerodynamic thrust of the wind turbine; L b represents the equivalent length of the blade; φ r represents the azimuth angle of the impeller; δF 1,fa represents the additional thrust on blade 1; δF 2,fa represents the additional thrust on blade 2; δF 3,fa represents the additional thrust on blade 3;

[0069] The equivalent aerodynamic torque of the wind turbine is the sum of the aerodynamic torque of the wind turbine and the additional torque of each blade; the aerodynamic force in the left and right directions of the wind turbine is calculated from the additional torque of each blade; based on the additional torque of each blade obtained above, the equivalent aerodynamic torque of the wind turbine and the aerodynamic force in the left and right directions of the wind turbine can be calculated, and the following matrix equation is established:

[0070]

[0071] In the above formula, T aero represents the equivalent aerodynamic torque of the wind turbine; F ss represents the aerodynamic force in the left and right directions of the wind turbine; T a represents the aerodynamic torque of the wind turbine; L bRepresents the equivalent length of the blade; φ r Represents the azimuth angle of the impeller; δT 1,a Represents the additional torque on blade 1; δT 2,a Represents the additional torque on blade 2; δT 3,a Represents the additional torque on blade 3.

[0072] Linearization of tower motion: The tower of a wind turbine is flexible. After being stressed, the tower will deform in three directions. However, the deformation of the tower in the vertical direction is very small compared to the deformation of the tower in the horizontal direction. Therefore, the deformation of the tower in the vertical direction can be ignored. Thus, it is assumed that the deformation of the tower only occurs in two directions in the horizontal plane: the front-back direction of the tower (parallel to the wind direction) and the left-right direction of the tower (perpendicular to the wind direction);

[0073] The equivalent force in the front-back direction of the tower top is composed of the aerodynamic thrust in the front-back direction of the wind turbine and the bending moment in the pitch direction of the wind turbine. The equivalent force in the left-right direction of the tower top is composed of the aerodynamic force in the left-right direction of the wind turbine and the aerodynamic torque of the wind turbine. The specific definitions are as follows:

[0074]

[0075] In the above formula, F ∑,fa Represents the equivalent force in the front-back direction of the tower top; F ∑,ss Represents the equivalent force in the left-right direction of the tower top; F fa Represents the aerodynamic thrust in the front-back direction of the wind turbine; K nod2fa Represents the equivalent coefficient from the pitch bending moment to the front-back thrust; M nod Represents the bending moment in the pitch direction of the wind turbine; F ss Represents the aerodynamic force in the left-right direction of the wind turbine; K a2ss Represents the equivalent coefficient from the aerodynamic torque to the left-right aerodynamic force; T aero Represents the equivalent aerodynamic torque of the wind turbine;

[0076] The deformation in the front-back direction of the tower can establish the second-order dynamic equation of the tower in the front-back direction. The deformation in the left-right direction of the tower can establish the second-order dynamic equation of the tower in the left-right direction. However, in order to consider the influence of the single-frequency effect (1P effect) of the wind turbine rotation on the tower vibration during the rotation of the wind turbine, the contribution of the left-right speed of the tower to the deformation in the front-back direction and the contribution of the front-back speed of the tower to the deformation in the left-right direction are added. Thus, the coupling effect of the deformation in the front-back and left-right directions of the tower is considered, and a linearized model of the tower in the front-back and left-right directions is established. Its matrix equation is as follows:

[0077]

[0078] In the above formula, Represents the first derivative of the displacement in the front-back direction of the tower top with respect to time; Represents the first derivative of the displacement in the left-right direction of the tower top with respect to time; Represents the first derivative of the front and rear speeds of the tower top with respect to time; Represents the first derivative of the left and right speeds of the tower top with respect to time; x fa Represents the front and rear displacements of the tower top; x ss Represents the left and right displacements of the tower top; v fa Represents the front and rear speeds of the tower top; v ss Represents the left and right speeds of the tower top; K fa Represents the stiffness coefficient in the front and rear directions of the tower top; D fa Represents the damping coefficient in the front and rear directions of the tower top; K ss Represents the stiffness coefficient in the left and right directions of the tower top; D ss Represents the damping coefficient in the left and right directions of the tower top; N b Represents the coupling coefficient between the front and rear and left and right of the tower; ω r Represents the rotational speed of the wind turbine; m t Represents the equivalent mass of the tower top; ε m Represents the uncertainty of the equivalent mass of the tower top; F ∑，fa Represents the equivalent force in the front and rear directions of the tower top; F ∑，ss Represents the equivalent force in the left and right directions of the tower top.

[0079] Tower load reduction control: According to the equivalent force in the front and rear directions of the tower top, the equivalent force in the left and right directions of the tower top, the front and rear speeds of the tower top, and the left and right speeds of the tower, the pitch command and the generator torque command are calculated and respectively superimposed on the pitch control and torque control loops of the unit to achieve the purpose of actively reducing the tower load; where:

[0080] The pitch command includes two parts of pitch commands, which are as follows:

[0081] The first part of the pitch command is used to reduce the load in the front and rear directions of the tower, and is specifically defined as follows:

[0082]

[0083] In the above formula, Represents the first part of the pitch command for blade 1; Represents the first part of the pitch command for blade 2; Represents the first part of the pitch command for blade 3; C F Represents the front and rear thrust reduction coefficient; F fa Represents the aerodynamic thrust in the front and rear directions of the wind turbine; C v Represents the front and rear damping addition coefficient of the tower top; v fa Represents the front and rear speeds of the tower top; C M Represents the pitch moment compensation coefficient; M nod Represents the pitch moment of the wind turbine; φ r Represents the azimuth angle of the impeller; θ f Represents the phase compensation angle;

[0084] The second part of the pitch command is used to reduce the loads in the left - right direction of the tower, and is specifically defined as follows:

[0085]

[0086] In the above formula, represents the second - part pitch command of blade 1; represents the second - part pitch command of blade 2; represents the second - part pitch command of blade 3; D F represents the left - right thrust reduction coefficient; F ss represents the aerodynamic force in the left - right direction of the wind turbine rotor; D v represents the left - right damping coefficient at the top of the tower; v ss represents the left - right speed at the top of the tower; φ r represents the azimuth angle of the impeller; θ s represents the phase compensation angle.

[0087] The generator torque command is used to reduce the loads in the left - right direction of the tower, and is specifically defined as follows:

[0088]

[0089] In the above formula, represents the generator torque command; E ∑ represents the left - right thrust reduction coefficient; F ∑，ss represents the equivalent force in the left - right direction at the top of the tower; E v represents the left - right damping coefficient at the top of the tower; v ss represents the left - right speed at the top of the tower.

[0090] Embodiment 2

[0091] This embodiment discloses a tower load - reduction control system for a wind turbine based on a linearized model, which is used to implement the tower load - reduction control method for a wind turbine based on a linearized model described in Embodiment 1. As Figure 1 shown, the system includes the following functional modules:

[0092] An aerodynamic linearization module, which is used to calculate the aerodynamic thrust and aerodynamic torque received by the wind turbine rotor, and then, based on the calculated aerodynamic thrust and aerodynamic torque, calculate the aerodynamic thrust in the front - rear direction of the wind turbine rotor, the bending moment in the pitch direction of the wind turbine rotor, the equivalent aerodynamic torque of the wind turbine rotor, and the aerodynamic force in the left - right direction of the wind turbine rotor;

[0093] A tower motion linearization module, which is used to calculate the equivalent force in the front - rear direction at the top of the tower and the equivalent force in the left - right direction at the top of the tower, and then, based on the calculated equivalent force in the front - rear direction at the top of the tower and the equivalent force in the left - right direction at the top of the tower, and considering the coupling effect of the deformation in the front - rear and left - right directions of the tower, increase the contribution of the left - right speed of the tower to the deformation in the front - rear direction and the contribution of the front - rear speed of the tower to the deformation in the left - right direction, and establish a linearized model in the front - rear, left - right directions of the tower;

[0094] The tower derating control module calculates the pitch command and the generator torque command based on the equivalent force in the front-back direction at the top of the tower, the equivalent force in the left-right direction at the top of the tower, the front-back speed at the top of the tower, and the left-right speed of the tower, and superimposes them onto the pitch control and torque control loops of the unit respectively to actively reduce the tower load.

[0095] Embodiment 3

[0096] This embodiment discloses a storage medium storing a program, which, when executed by a processor, implements the wind turbine tower derating control method based on a linearized model described in Embodiment 1.

[0097] The storage medium in this embodiment may be a magnetic disk, an optical disc, a computer memory, a read-only memory (ROM), a random access memory (RAM), a USB flash drive, a mobile hard disk, or other media.

[0098] Embodiment 4

[0099] This embodiment discloses a computing device including a processor and a memory for storing a program executable by the processor. When the processor executes the program stored in the memory, it implements the wind turbine tower derating control method based on a linearized model described in Embodiment 1.

[0100] 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 processor functions.

[0101] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to 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 tower load reduction control method for a wind turbine based on a linearized model, characterized in that, Do the following: Aerodynamic linearization: including the calculation of aerodynamic thrust and aerodynamic torque on the wind rotor, and then calculating the aerodynamic thrust in the front and rear directions of the wind rotor, the bending moment in the pitch direction of the wind rotor, the equivalent aerodynamic torque of the wind rotor, and the aerodynamic force in the left and right directions of the wind rotor based on the calculated aerodynamic thrust and aerodynamic torque; Tower motion linearization: including the calculation of the equivalent force in the front-to-back direction of the tower top and the equivalent force in the left-to-right direction of the tower top. The equivalent force in the front-to-back direction of the tower top is composed of the aerodynamic thrust in the front-to-back direction of the wind rotor and the bending moment in the pitch direction of the wind rotor, and the equivalent force in the left-to-right direction of the tower top is composed of the equivalent aerodynamic torque of the wind rotor and the aerodynamic force in the left-to-right direction of the wind rotor. Then, based on the calculated equivalent force in the front-to-back direction and the equivalent force in the left-to-right direction of the tower top, and considering the coupling effect of the front-to-back and left-to-right deformation of the tower, the contribution of the left-to-right speed of the tower to the front-to-back deformation and the contribution of the front-to-back speed of the tower to the left-to-right deformation are added, and a linearized model of the front-to-back, left-to-right direction of the tower is established; Tower load reduction control: Based on the equal forces in the front and rear directions of the tower top, the equal forces in the left and right directions of the tower top, the front and rear speed of the tower top, and the left and right speed of the tower, the pitch control command and the generator torque command are calculated and superimposed on the pitch control and torque control loops of the unit, respectively, to actively reduce the tower load; The tower of a wind turbine is flexible. When subjected to force, the tower will deform in three directions. However, the deformation of the tower in the vertical direction is very small compared to the horizontal deformation of the tower. Therefore, the deformation of the tower in the vertical direction can be ignored. It is assumed that the deformation of the tower only occurs in two directions in the horizontal plane: the front-to-back direction of the tower parallel to the wind direction and the left-to-right direction of the tower perpendicular to the wind direction. The equivalent force in the front-to-back direction of the tower top is composed of the aerodynamic thrust in the front-to-back direction of the wind rotor and the bending moment in the pitch direction of the wind rotor. The equivalent force in the left-to-right direction of the tower top is composed of the aerodynamic force in the left-to-right direction of the wind rotor and the aerodynamic torque of the wind rotor. The specific definitions are as follows: In the above formula, F ∑,fa represents the equivalent force in the front-back direction at the top of the tower; F ∑,ss represents the equivalent force in the left-right direction at the top of the tower; F fa represents the aerodynamic thrust in the front-back direction of the wind turbine; K nod2fa represents the equivalent coefficient from the pitching moment to the front-back thrust; M nod represents the pitching moment of the wind turbine; F ss represents the aerodynamic force in the left-right direction of the wind turbine; K a2ss represents the equivalent coefficient from the aerodynamic torque to the left-right aerodynamic force; T aero represents the equivalent aerodynamic torque of the wind turbine; The deformation of the tower in the front and rear directions can establish the second-order dynamic equation of the tower, and the deformation of the tower in the left and right directions can establish the second-order dynamic equation of the tower. However, in order to consider the influence of the single frequency effect of the wind rotor rotation, that is, the 1P effect, on the vibration of the tower during the rotation of the wind rotor, the contribution of the left and right speed of the tower to the deformation in the front and rear directions and the contribution of the front and rear speed of the tower to the deformation in the left and right directions are added. So far, the coupling effect of the deformation of the tower in the front and rear directions and the left and right directions is considered, and the linearized model of the tower in the front and rear directions and the left and right directions is established. The matrix equation is as follows: In the above formula, represents the first derivative of the front - rear displacement of the tower top with respect to time; represents the first derivative of the left - right displacement of the tower top with respect to time; represents the first derivative of the front - rear velocity of the tower top with respect to time; represents the first derivative of the left - right velocity of the tower top with respect to time; x fa represents the front - rear displacement of the tower top; x ss represents the left - right displacement of the tower top; v fa represents the front - rear velocity of the tower top; v ss represents the left - right velocity of the tower top; Kfa represents the stiffness coefficient in the front - rear direction of the tower top; Dfa represents the damping coefficient in the front - rear direction of the tower top; Kss represents the stiffness coefficient in the left - right direction of the tower top; Dss represents the damping coefficient in the left - right direction of the tower top; Nb represents the coupling coefficient between the front - rear and left - right directions of the tower; ω r represents the rotational speed of the wind turbine; m t represents the equivalent mass of the tower top; ε m represents the uncertainty of the equivalent mass of the tower top; F ∑,fa represents the equivalent force in the front - rear direction of the tower top; F ∑,ss represents the equivalent force in the left - right direction of the tower top.

2. The tower load reduction control method for a wind turbine based on a linearized model according to claim 1, characterized in that: When the wind rotor faces the wind direction and the air flows through the wind rotor, the wind rotor will be subjected to aerodynamic thrust and aerodynamic torque. Based on aerodynamic theory, the aerodynamic thrust of the wind rotor is proportional to the air density, the square of the wind rotor radius, the square of the average wind speed and the thrust coefficient. The aerodynamic torque of the wind rotor is proportional to the air density, the cube of the wind rotor radius, the square of the average wind speed and the torque coefficient. The specific expressions are as follows: In the above formula, F a represents the aerodynamic thrust of the wind turbine; T a represents the aerodynamic torque of the wind turbine; ρ represents the air density; π represents the constant of pi; R represents the radius of the wind turbine; v represents the average wind speed; λ is the tip speed ratio; β represents the average blade angle; C t (λ,β) represents the thrust coefficient, which is a function of the tip speed ratio and the average blade angle; C q (λ,β) represents the torque coefficient, which is a function of the tip speed ratio and the average blade angle; The aerodynamic thrust of the wind rotor is the cumulative sum of the thrusts received by each blade. Since the wind rotor is affected by wind shear and turbulence, the thrust received by each blade is not the same. Considering the thrust received by each blade, the following expression is established: In the above formula, δF 1,fa represents the additional thrust on blade 1; δF 2,fa represents the additional thrust on blade 2; δF 3,fa represents the additional thrust on blade 3; μ ρ represents the uncertainty of air density; represents the partial derivative of the aerodynamic thrust of the wind turbine with respect to the pitch angle; δβ1 represents the additional pitch angle of blade 1; δβ2 represents the additional pitch angle of blade 2; δβ3 represents the additional pitch angle of blade 3; represents the partial derivative of the aerodynamic thrust of the wind turbine with respect to the average wind speed; δν1 represents the additional wind speed of blade 1; δν2 represents the additional wind speed of blade 2; δν3 represents the additional wind speed of blade 3; The aerodynamic torque of the wind turbine rotor is the sum of the torques received by each blade. Due to the influence of wind direction deviation and turbulence on the wind turbine rotor, the torques received by each blade are not the same. Considering the torques received by each blade, the following expression is established: In the above formula, δT 1,a represents the additional torque on blade 1; δT 2,a represents the additional torque on blade 2; δT 3,a represents the additional torque on blade 3; μ ρ represents the uncertainty of air density; represents the partial derivative of the aerodynamic torque of the wind turbine with respect to the pitch angle; δβ1 represents the additional pitch angle of blade 1; δβ2 represents the additional pitch angle of blade 2; δβ3 represents the additional pitch angle of blade 3; represents the partial derivative of the aerodynamic torque of the wind turbine with respect to the average wind speed; δν1 represents the additional wind speed of blade 1; δν2 represents the additional wind speed of blade 2; δν3 represents the additional wind speed of blade 3; The aerodynamic thrust in the front and rear directions of the wind turbine rotor is the sum of the aerodynamic thrust of the wind turbine rotor and the additional thrust of each blade; the bending moment in the pitch direction of the wind turbine rotor is calculated from the additional thrust of each blade; based on the additional thrust of each blade obtained previously, the aerodynamic thrust in the front and rear directions of the wind turbine rotor and the bending moment in the pitch direction of the wind turbine rotor can be calculated, and the following matrix equation is established: In the above formula, F fa represents the aerodynamic thrust in the front-rear direction of the wind turbine rotor; M nod represents the bending moment in the pitch direction of the wind turbine rotor; F a represents the aerodynamic thrust of the wind turbine rotor; L b represents the equivalent length of the blade; φ r represents the azimuth angle of the impeller; δF 1,fa represents the additional thrust received by blade 1; δF 2,fa represents the additional thrust received by blade 2; δF 3,fa represents the additional thrust received by blade 3; The equivalent aerodynamic torque of the wind turbine rotor is the sum of the aerodynamic torque of the wind turbine rotor and the additional torque of each blade; the aerodynamic force in the left and right directions of the wind turbine rotor is calculated from the additional torque of each blade; based on the additional torque of each blade obtained previously, the equivalent aerodynamic torque of the wind turbine rotor and the aerodynamic force in the left and right directions of the wind turbine rotor can be calculated, and the following matrix equation is established: In the above formula, T aero represents the equivalent aerodynamic torque of the wind turbine rotor; F ss represents the aerodynamic force of the wind turbine rotor in the left-right direction; T a represents the aerodynamic torque of the wind turbine rotor; L b represents the equivalent length of the blade; φ r represents the azimuth angle of the impeller; δT 1,a represents the additional torque received by blade 1; δT 2,a represents the additional torque received by blade 2; δT 3,a represents the additional torque received by blade 3.

3. The tower load reduction control method for a wind turbine based on a linearized model according to claim 1, characterized in that: The pitch command includes two parts of pitch commands, which are as follows: The first part of the pitch command is used to reduce the load in the front and rear directions of the tower, and the specific definition is as follows: In the above formula, represents the pitch command for the first part of blade 1; represents the pitch command for the first part of blade 2; represents the pitch command for the first part of blade 3; C F represents the front and rear thrust reduction coefficient; F fa represents the aerodynamic thrust in the front and rear directions of the wind turbine rotor; C v represents the front and rear damping coefficient at the top of the tower; v fa represents the front and rear speed at the top of the tower; C M represents the pitch moment compensation coefficient; M nod represents the moment in the pitch direction of the wind turbine rotor; φ r represents the azimuth angle of the impeller; θ f represents the phase compensation angle; The second part of the pitch command is used to reduce the load in the left and right directions of the tower, and the specific definition is as follows: In the above formula, represents the pitch command for the second part of blade 1; represents the pitch command for the second part of blade 2; represents the pitch command for the second part of blade 3; D F represents the left and right thrust reduction coefficient; F ss represents the aerodynamic force in the left and right directions of the wind turbine rotor; D v represents the left and right damping coefficient at the top of the tower; v ss represents the left and right speed at the top of the tower; φ r represents the azimuth angle of the impeller; θ s represents the phase compensation angle.

4. A method for reducing the load of a wind turbine tower based on a linearized model according to claim 1, characterized in that: The generator torque command is used to reduce the load in the left and right directions of the tower, and the specific definition is as follows: In the above formula, represents the generator torque command; E ∑ represents the left and right thrust reduction coefficient; F ∑,ss represents the equivalent force in the left and right directions at the top of the tower; E v represents the left and right damping addition coefficient at the top of the tower; v ss represents the left and right speed at the top of the tower.

5. A control system for reducing the load of a wind turbine tower based on a linearized model, characterized in that For implementing the wind turbine tower load reduction control method based on a linearized model according to any one of claims 1 to 4, it includes: An aerodynamic linearization module, which is used to calculate the aerodynamic thrust and aerodynamic torque received by the wind turbine rotor, and then calculate the aerodynamic thrust in the front and rear directions of the wind turbine rotor, the bending moment in the pitch direction of the wind turbine rotor, the equivalent aerodynamic torque of the wind turbine rotor, and the aerodynamic force in the left and right directions of the wind turbine rotor according to the calculated aerodynamic thrust and aerodynamic torque; A tower motion linearization module, which is used to calculate the equivalent force in the front and rear directions of the tower top and the equivalent force in the left and right directions of the tower top, and then, according to the calculated equivalent force in the front and rear directions of the tower top and the equivalent force in the left and right directions of the tower top, and considering the coupling effect of the deformation in the front and rear and left and right directions of the tower, increase the contribution of the left and right speed of the tower to the deformation in the front and rear directions and the contribution of the front and rear speed of the tower to the deformation in the left and right directions, and establish a linearized model in the front, rear, left, and right directions of the tower; A tower load reduction control module, which calculates the pitch command and the generator torque command according to the equivalent force in the front and rear directions of the tower top, the equivalent force in the left and right directions of the tower top, the front and rear speed of the tower top, and the left and right speed of the tower, and superimposes them onto the pitch control and torque control loops of the unit respectively to actively reduce the tower load.

6. A storage medium storing a program, characterized in that When the program is executed by the processor, it implements the wind turbine tower load reduction control method based on a linearized model according to any one of claims 1 to 4.

7. A computing device, including a processor and a memory for storing executable programs of the processor, characterized in that When the processor executes the program stored in the memory, it implements the wind turbine tower load reduction control method based on a linearized model according to any one of claims 1 to 4.

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