Dynamic load decoupling calculation correction method considering wind turbine generator transmission chain

Abstract

The invention discloses a dynamic load decoupling calculation correction method considering a transmission chain of a wind turbine generator. The dynamic load decoupling calculation correction method comprises the following steps: establishing a dynamic model of an overall system including the transmission chain by considering inertia force and damping force of the overall system; decomposing the established kinetic equation into two subsystems through boundary conditions; five-degree-of-freedom displacement, except torsion, of the transmission chain unit is considered, and a kinetic equation of the transmission chain unit is established; and according to the solution of the kinetic equation of the transmission chain unit, the decoupling calculation of the whole system is corrected. According to the invention, the problem of accurate reproduction of the non-torque load of the tested wind turbine generator by the axial conjugate loading unit in a full-size ground test platform of the wind turbine generator is solved. According to the method, a rigid-flexible coupling equivalent dynamic model of the transmission chain structure is built, the inertia force and the damping force of the transmission chain structure in the movement process are innovatively taken into consideration, and finally decoupling correction of the non-torque dynamic load of the hub center of the tested wind turbine generator is achieved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of wind turbine test and detection, and particularly relates to a dynamic load decoupling calculation correction method considering a wind turbine transmission chain. BACKGROUND

[0002] In recent years, with the increasing demand for getting rid of traditional fossil fuels such as oil, coal and natural gas, the energy pattern has tilted significantly to renewable energy. Wind energy has become a very potential power generation choice. However, due to the complex and changeable marine environment, the design, construction and operation of offshore wind power facilities face many challenges. During the operation of the wind turbine, its transmission system needs to withstand the coupling effect of various environmental loads such as wind, wave, flow and soil. These loads are transmitted to the transmission chain through the impeller and the tower. Under the long-term load action, the transmission chain becomes a key component prone to failure, and its state directly affects the service life and power generation efficiency of the unit. With the increasing size of the unit and the increasingly complex operating environment, relying on field measurement to evaluate the safety of the transmission chain is not only costly, but also technically difficult. Therefore, before the new type of wind turbine is put into commercial operation, it is necessary to carry out full-conditions testing on its transmission chain by using a full-size ground test platform to ensure the operation reliability.

[0003] In the test platform, the torque load is provided by a drag motor and a flexible coupling, and the non-torque load is applied by a five-degree-of-freedom load generated by the coordinated action of multiple hydraulic actuators. The commonly used non-torque loading technology mainly includes three forms of disc-type symmetric loading, disc-type eccentric loading and shaft-type conjugate loading. With the continuous improvement of single machine capacity, the shaft-type conjugate loading unit gradually becomes one of the mainstream ways to apply non-torque load in the full-size test platform of large-capacity wind turbines due to its simple structure and strong dynamic response capability.

[0004] During the test process, accurately reproducing the target load is a key technical challenge. Existing researches on non-torque loading mainly focus on load decomposition and control strategy of the loading unit, often ignoring the influence of inertia force and damping force generated in the motion process of the transmission chain structure on the loading unit. Especially under dynamic loading conditions, such force effects cannot be ignored.

[0005] Based on this, a correction method considering the influence of the transmission chain on the non-torque dynamic load decoupling calculation of the full-size ground test platform of wind turbines is proposed, which takes into account the inertia force and damping force of the transmission chain in the motion process, aiming to improve the reproduction accuracy of the non-torque load of the wind turbine. SUMMARY

[0006] The application is proposed to solve the problems existing in the prior art, and the purpose is to provide a dynamic load decoupling calculation correction method considering a wind turbine transmission chain.

[0007] The technical scheme of the application is: a dynamic load decoupling calculation correction method considering the transmission chain of a wind turbine generator, comprising the following steps: A. considering the inertia force and damping force of the overall system, a dynamic model of the overall system including the transmission chain is established; B. the dynamic equation obtained is decomposed into two subsystems through boundary conditions; C. considering the displacement of the five degrees of freedom of the transmission chain unit except torsion, a dynamic equation of the transmission chain unit is established; D. the overall system decoupling calculation is corrected according to the solution of the dynamic equation of the transmission chain unit.

[0008] Further, in step A, the dynamic model needs to be simplified according to the dynamic characteristics of the actual structure of the system, a multi-body dynamic model is established, and then the dynamic model is established.

[0009] Further, in step B, the dynamic equation obtained is decomposed into two subsystems through boundary conditions, and the two subsystems are a loaded unit multi-body dynamic model and a transmission chain system dynamic model, which are decomposed into two subsystems at node 1.

[0010] Further, in step B, the load at node 1 is a known item, and as a common node 1, the displacement, velocity and acceleration at node 1 are equal.

[0011] Further, in step C, the dynamic equation of the transmission chain unit is established, including obtaining the mass matrix of the transmission chain unit, and the specific process is as follows: First, the mass matrix of the spring mass system in the transmission chain system dynamic model can be directly determined, considering that the nodes 1 and 3 on both sides are massless nodes with only rigidity, and the mass of the two nodes is zero; Then, consider that the node 2 in the middle is a concentrated mass space rigid body; Finally, the mass matrix expression of the transmission chain unit is obtained.

[0012] Further, in step C, after obtaining the mass matrix, the corrected stiffness matrix is obtained, and the specific process is as follows: First, since the transmission chain is simplified as a space rigid body in the process of obtaining the mass matrix, the displacements of each degree of freedom of the space rigid body will affect each other; Then, the influence of the displacement of the space rigid body in each degree of freedom on the entire stiffness matrix is considered; Finally, after considering the mutual influence of the displacements of each degree of freedom, the corrected stiffness matrix is obtained.

[0013] Further, in step C, after obtaining the stiffness matrix, the dynamic equation of the system is obtained, and the specific process is as follows: Firstly, the Rayleigh damping form is used to represent the overall damping matrix of the transmission chain model; Then, the dynamic equation is obtained based on the representation of the Rayleigh damping form.

[0014] Further, step D is modified according to the solution of the transmission chain unit dynamic equation, including obtaining the system motion response at each time step, and the specific process is as follows: Based on the known dynamic equation and the known load at node 1, the system motion response at each time step can be obtained by solving the dynamic equation by Newmark-β method.

[0015] Further, after obtaining the system motion response at each time step, step D further obtains the displacement, velocity and acceleration of each node of the loading system, and the specific process is as follows: Since the displacement, velocity and acceleration of node 1 are known, the motion equation of the loading system can be solved by numerical calculation method to obtain the displacement, velocity and acceleration of each node of the loading system.

[0016] Further, after obtaining the displacement, velocity and acceleration of each node of the loading system, step D finally modifies the overall system decoupling calculation, and the specific process is as follows: According to the solution of the motion equation of the loading system, various decoupling methods are used to complete the modification calculation considering the decoupling influence of the transmission chain on the dynamic load.

[0017] The beneficial effects of the present application are as follows: The present application precisely solves the problem of precise reproduction of non-torque load of the measured wind turbine by the shaft type conjugate loading unit in the full-size ground test platform of the wind turbine. The present application builds a rigid-flexible coupling equivalent dynamic model of the transmission chain structure, and innovatively considers the inertia force and damping force of the transmission chain structure in the motion process, and finally realizes the decoupling modification of the non-torque dynamic load at the hub center of the measured wind turbine. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is the dynamic model of the system in the present application; Figure 2 is the simplified dynamic model of the loading unit in the present application; Figure 3 is the dynamic model of the transmission chain system in the present application. DETAILED DESCRIPTION

[0019] Hereinafter, the present application will be described in detail with reference to the drawings and examples: As Figures 1 to 3 shown, a dynamic load decoupling calculation modification method considering the transmission chain of a wind turbine includes the following steps: A. Consider the inertia force and damping force of the whole system to establish the dynamic model of the whole system including the transmission chain; B. The established dynamic equation is decomposed into two subsystems through boundary conditions; C. Considering the displacement of the five degrees of freedom of the transmission chain unit except torsion, the dynamic equation of the transmission chain unit is established; D. According to the solution of the dynamic equation of the transmission chain unit, the decoupling calculation of the whole system is modified.

[0020] In step A, the dynamic model needs to be simplified according to the dynamic characteristics of the actual structure of the system, to establish a multi-body dynamic model, and then to establish the dynamic model.

[0021] In step B, the established dynamic equation is decomposed into two subsystems through boundary conditions, and the two subsystems are the loading unit multi-body dynamic model and the transmission chain system dynamic model, which are decomposed into two subsystems at node 1.

[0022] In step B, the load at node 1 is a known item, and as a common node 1, the displacement, velocity and acceleration at node 1 are equal.

[0023] In step C, the dynamic equation of the transmission chain unit is established, including obtaining the mass matrix of the transmission chain unit, and the specific process is as follows: Firstly, the mass matrix of the spring mass system in the transmission chain system dynamic model can be directly determined, considering that the nodes 1 and 3 on both sides are massless nodes with only rigidity, and the mass of the two nodes is zero; Then, consider the node 2 in the middle as a concentrated mass space rigid body; Finally, the mass matrix expression of the transmission chain unit is obtained.

[0024] In step C, after obtaining the mass matrix, the modified stiffness matrix is obtained, and the specific process is as follows: Firstly, since the transmission chain is simplified as a space rigid body in the process of obtaining the mass matrix, the displacements of each degree of freedom of the space rigid body will affect each other; Then, the influence of the displacement of the space rigid body in each degree of freedom on the whole stiffness matrix is considered; Finally, after considering the mutual influence of the displacement of each degree of freedom, the modified stiffness matrix is obtained.

[0025] In step C, after obtaining the stiffness matrix, the dynamic equation of the system is obtained, and the specific process is as follows: Firstly, the Rayleigh damping form is adopted to characterize the overall damping matrix of the transmission chain model; Then, based on the characterization of the Rayleigh damping form, the dynamic equation is obtained.

[0026] Step D is modified according to the solution of the transmission chain unit dynamics equation, including obtaining the system motion response at each time step, the specific process is as follows: Based on the known dynamics equation and the known load at node 1, the system motion response at each time step can be obtained by solving the dynamics equation by Newmark-β method.

[0027] Step D obtains the displacement, velocity and acceleration of each node of the loading system after obtaining the system motion response at each time step, and the specific process is as follows: Since the displacement, velocity and acceleration of node 1 are known, the motion equation of the loading system can be solved by numerical calculation method to obtain the displacement, velocity and acceleration of each node of the loading system.

[0028] Step D finally modifies the overall system decoupling calculation after obtaining the displacement, velocity and acceleration of each node of the loading system, and the specific process is as follows: According to the solution of the motion equation of the loading system, the modification calculation considering the decoupling influence of the transmission chain on the dynamic load is completed by various decoupling methods.

[0029] Specifically, step A considers the inertia force and damping force of the overall system to establish the dynamics model of the overall system including the transmission chain, as follows: Firstly, considering the structural characteristics of the entire ground loading test platform, the loading device is simplified as a flexible space beam, and a multi-body dynamics model of the loading unit is established. This patent focuses on the transmission chain structure, and the modeling and simplification of the loading unit are not described; Then, according to the dynamics characteristics of the transmission chain, its inertia should be considered in calculation, so it is simplified as a spatial rigid body model, but the transmission chain structure itself has a certain flexibility, so a spring-mass equivalent model is formed by linking springs at both ends of the spatial rigid body model, and the transmission chain structure is simplified as a spring-mass model; Then, the transmission chain model is discretized into 2 units, corresponding to form 3 nodes, node 2 is the spatial rigid body model obtained by simplifying the transmission chain; Finally, the dynamics model of the entire system including the transmission chain and the loading device after discretization is obtained, as shown in Figure 1 .

[0030] Specifically, step B decomposes the established dynamics equation into two subsystems through boundary conditions, and the specific process is as follows: First, Figure 2 The simplified dynamics model of the loading unit is shown, wherein the equivalent load generates 5-degree-of-freedom non-torque load at the center of the measured wind turbine hub. At the same time, The target load is usually the ground test load of the measured wind turbine, which is a known item; Then, since the load at node 1 is known, the displacement, velocity and acceleration at node 1 are Figure 1 The overall dynamic model shown in FIG. 1 is decomposed into two subsystems at node 1, and the displacement, velocity and acceleration of the two subsystems at node 1 are equal; Finally, the decomposed dynamic model of the transmission chain system is shown in FIG. 3, wherein Figure 3 The force and the reaction force are a set of and .

[0031] Specifically, the mass matrix of the transmission chain unit in step C is: ; Wherein, is the mass of the equivalent spatial rigid body, is the moment of inertia of the spatial rigid body about the y-axis, is the moment of inertia of the spatial rigid body about the z-axis.

[0032] Specifically, the corrected system stiffness matrix in step C is: ; Wherein ; ; ; ; ; ; .

[0033] Specifically, after obtaining the stiffness matrix in step C, the dynamic equation of the system is obtained, and the specific process is as follows: First, the overall damping matrix of the transmission chain model is characterized by Rayleigh damping: ; Wherein, , The first and second natural frequencies of the system, are the corresponding damping coefficients, which are usually taken as 0.02-0.05; Then, the dynamic equation of the system is obtained, which is as follows: (1) Wherein, and respectively represent the displacement, velocity, acceleration and load of each node degree of freedom direction in the transmission chain system.

[0034] Specifically, in step D, since is known, equation (1) can be solved by Newmark-β method to obtain the system motion response of each time step .

[0035] Since the displacement, velocity and acceleration of node 1 are known, the motion equation of the loading system can be solved by numerical calculation method to obtain the displacement, velocity and acceleration of each node of the loading system.

[0036] Finally, according to the solving result of the motion equation of the loading system, various decoupling methods can be used to complete the correction calculation considering the decoupling influence of the transmission chain on the dynamic load.

[0037] The application accurately solves the problem of accurately reproducing the non-torque load of the measured wind turbine by the shaft type conjugate loading unit in the full-size ground test platform of the wind turbine. The application builds a rigid-flexible coupling equivalent dynamics model of the transmission chain structure, innovatively considers the inertia force and damping force of the transmission chain structure in the motion process, and finally realizes the decoupling correction of the non-torque dynamic load at the hub center of the measured wind turbine.

Claims

1. A method for decoupling calculation and correction of dynamic loads in wind turbine drive trains, characterized in that: Includes the following steps: A. Consider the inertial forces and damping forces of the overall system and establish a dynamic model of the entire system including the transmission chain; B. Decompose the established dynamic equations into two subsystems using boundary conditions; C. Considering the displacements of the five degrees of freedom of the transmission chain unit excluding torsion, establish the dynamic equations of the transmission chain unit; D. Based on the solution of the dynamic equation of the transmission chain unit, the decoupling calculation of the overall system is corrected.

2. The method for dynamic load decoupling calculation correction considering the wind turbine drive train according to claim 1, characterized in that: In step A, the dynamic model needs to be simplified based on the dynamic characteristics of the actual system structure to establish a multibody dynamic model, and then the dynamic model is established.

3. The method for dynamic load decoupling calculation correction considering the wind turbine drive train according to claim 1, characterized in that: Step B decomposes the obtained dynamic equations into two subsystems through boundary conditions. The two subsystems are the multibody dynamics model of the loading unit and the dynamics model of the transmission chain system, which are decomposed into two subsystems at node 1.

4. The method for dynamic load decoupling calculation correction considering the wind turbine drive train according to claim 2, characterized in that: In step B, the load at node 1 is a known item, and as a shared node 1, the displacement, velocity, and acceleration at node 1 are equal.

5. The method for dynamic load decoupling calculation correction considering the wind turbine drive train according to claim 1, characterized in that: Step C establishes the dynamic equations of the transmission chain unit, including obtaining the mass matrix of the transmission chain unit. The specific process is as follows: First, the mass matrix of the spring-mass block system in the dynamic model of the transmission chain system can be directly determined. It is assumed that nodes 1 and 3 on both sides are massless nodes with only rigidity, and the mass of the two nodes is zero. Then, the middle node 2 is considered to be a lumped-mass spatial rigid body; Then, the mass matrix expression of the transmission chain unit can be obtained.

6. The method for dynamic load decoupling calculation correction considering the wind turbine drive train according to claim 5, characterized in that: In step C, after obtaining the mass matrix, the corrected stiffness matrix is ​​obtained. The specific process is as follows: First, since the transmission chain is simplified to a spatial rigid body during the process of obtaining the mass matrix, the displacements of each degree of freedom of the spatial rigid body will affect each other; Then, we need to consider the effect of the displacement of the spatial rigid body in each degree of freedom on the entire stiffness matrix; Finally, after considering the mutual influence of displacements in each degree of freedom, the corrected stiffness matrix is ​​obtained.

7. The method for dynamic load decoupling calculation correction considering the wind turbine drive train according to claim 1, characterized in that: In step C, after obtaining the stiffness matrix, the dynamic equations of the system are obtained. The specific process is as follows: First, the overall damping matrix of the transmission chain model is characterized using the Rayleigh damping form. Then, based on the Rayleigh damping form of characterization, the dynamic equations are obtained.

8. The method for dynamic load decoupling calculation correction considering the wind turbine drive train according to claim 1, characterized in that: Step D involves correcting the decoupling calculation of the overall system based on the solution of the dynamic equations of the transmission chain unit, including obtaining the system motion response at each time step. The specific process is as follows: Based on the known dynamic equations and the known load at node 1, the system motion response at each time step can be obtained by solving the dynamic equations using the Newmark-β method.

9. The method for dynamic load decoupling calculation correction considering the wind turbine drive train according to claim 8, characterized in that: Step D, after obtaining the system motion response at each time step, further obtains the displacement, velocity, and acceleration of each node in the loaded system. The specific process is as follows: Since the displacement, velocity, and acceleration of node 1 are known, the motion equations of the loading system can be solved using numerical calculation methods to obtain the displacement, velocity, and acceleration of each node in the loading system.

10. The method for decoupling calculation and correction of dynamic load considering the wind turbine drive train according to claim 9, characterized in that: Step D, after obtaining the displacement, velocity, and acceleration of each node in the loading system, finally corrects the decoupling calculation of the overall system. The specific process is as follows: Based on the solution results of the motion equations of the loading system, the correction calculation considering the decoupling effect of the transmission chain on the dynamic load is completed by relying on various decoupling methods.

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