Active control method for vibration reduction of large wind turbine generator

Abstract

The invention provides an active control method for vibration reduction of a large wind turbine generator. According to the method, an electrical control system of a wind turbine generator is established, variable structure sliding mode control is adopted in a rotating speed ring in a machine side rectifier, model prediction control is adopted in a current ring, the variable structure sliding mode control and the model prediction control are combined, and a comprehensive control system is established; and the vibration influence of wind speed abrupt change and electromagnetic torque fluctuation on the wind turbine generator is dealt with. The sliding mode control is used for enhancing the quick response capability of the system under the condition of sudden wind speed change and reducing overshoot of the rotating speed and the torque, and the model prediction control optimizes the control of a current loop and remarkably inhibits harmonic waves in the system. Compared with a traditional control method, the control strategy of the method has remarkable advantages in the aspects of improving the dynamic response speed, reducing electromagnetic torque fluctuation and reducing mechanical system vibration, and therefore the overall performance and reliability of the wind turbine generator are effectively improved.

Description

Technical Field

[0001] The invention relates to the technical field of wind power generation, and in particular to an active vibration reduction control method for a large wind turbine generator set. Background Art

[0002] As a major green energy source, wind power generation has become an important part of the energy structure of various countries. However, during the operation of wind turbines, due to the vibration of the mechanical system, they often face failure and shutdown, which in turn leads to significant economic losses. These problems have attracted great attention from the industry and academia, and the dynamic characteristics of wind turbines and their vibration reduction control methods still need to be further studied.

[0003] Traditional research on wind turbine vibration reduction has mainly focused on passive control methods, especially the suppression of torsional vibration. However, passive control methods usually rely on specific hardware structure designs, are difficult to achieve dynamic adjustment, have a single application scenario, and are relatively expensive. Therefore, in recent years, active control methods have gradually become a hot topic in the field of wind power research. Active control methods use electrical control systems to effectively suppress mechanical system vibrations, have high flexibility, do not require the introduction of additional hardware, and have relatively low costs. Traditional control methods, such as proportional integral (PI) control, are simple and easy to implement, but they are not adequate when dealing with complex nonlinear vibrations and harmonic problems, so existing research has gradually turned its attention to more advanced control methods. Summary of the invention

[0004] The purpose of the present invention is to provide a large wind turbine active vibration reduction control method to solve the problems existing in the prior art.

[0005] The technical solution adopted to achieve the purpose of the present invention is as follows: a large-scale wind turbine active vibration reduction control method, in which the speed loop in the machine-side rectifier in the electrical control system adopts variable structure sliding mode control, and the current loop adopts model predictive control; the variable structure sliding mode control method and the model predictive control method are combined to achieve vibration suppression and harmonic suppression of the wind turbine transmission system. Among them, the sliding mode control method is used to enhance the system's rapid response capability under sudden changes in wind speed and reduce overshoot of speed and torque. The model predictive control method is used to optimize the control of the machine-side rectifier current loop and suppress harmonics in the system.

[0006] Furthermore, the model predictive control is combined with harmonic suppression. The model predictive control method is adopted in the current loop, and the harmonic suppression mechanism is introduced to suppress the harmonic problem in the motor and reduce the electromagnetic torque fluctuation.

[0007] The present invention also discloses a large-scale wind turbine vibration reduction active control system, comprising a communication module, a control module and a storage module. The communication module is connected to the electrical system for communication. The storage module is equipped with a sliding mode controller and a model prediction controller. The storage module stores an execution instruction. The execution instruction is configured to execute the large-scale wind turbine vibration reduction active control method according to claim 1 or 2 when executed by the control module.

[0008] Furthermore, the model predictive controller predicts and adjusts the control input in real time based on the value function and the rolling optimization method to ensure the optimal control effect of the system under complex working conditions.

[0009] The present invention also discloses a method for constructing the active control system for vibration reduction of the large wind turbine generator set, comprising the following steps:

[0010] 1) Establish an electrical control system; Establish an electrical control system including generators and machine-side rectifiers.

[0011] 2) Design a sliding mode controller. Based on the variable coefficient exponential sliding mode control method, a sliding mode controller for the generator side rectifier speed loop control is designed to improve the dynamic response performance of the wind turbine under sudden changes in wind speed. The sliding mode controller is modified on the basis of the exponential reaching law, and a variable coefficient exponential reaching law is designed. Its control law is:

[0012]

[0013] Among them, ε>0, k>0 are design parameters, x is the state of the system, and s is the sliding surface function. By designing a specific reaching law, the system can quickly return to the sliding surface when subjected to external disturbances and maintain the stability of the system.

[0014] 3) Design a model predictive controller. Step 3) specifically includes the following sub-steps:

[0015] 3.1) Establishment of prediction model: Discretize the motor model and rewrite the dq axis current into a form containing time variables. The control period of the controller is recorded as T and is small enough to establish a discrete prediction model of the motor.

[0016] 3.2) Selection of value function: The value function is a constraint condition in model predictive control, which is used to set the judgment rule for predicting the optimal value. The value function is selected based on the established current prediction model. Take the predicted current at time k in the two-phase rotating coordinate system and the current reference current The difference is used as the evaluation index, and the final value function is as follows:

[0017]

[0018] in, Represents the predicted current. Indicates the reference current

[0019] 3.3) Implementation of rolling optimization: Rolling optimization is performed through the prediction model to adjust the current control in real time to reduce the impact of harmonics.

[0020] 4) Controller parameter optimization: Optimize controller parameters through the simulation platform to ensure the synergy between the sliding mode controller and the model predictive controller, thereby achieving effective vibration reduction of the wind turbine mechanical system.

[0021] The present invention also discloses a large wind turbine generator set, comprising the large wind turbine generator set vibration reduction active control system as described above, as well as a transmission system and an electrical system. The electrical system responds to the control strategy instruction received from the control system, and the transmission system performs corresponding actions. The large wind turbine generator set realizes active vibration suppression of the transmission system through the electrical system, and realizes flexible adjustment and optimization control of the dynamic working conditions of the system.

[0022] Furthermore, the transmission system includes an impeller, a main shaft, a gear transmission system and a generator.

[0023] The technical effects of the present invention are unquestionable:

[0024] A. By designing the exponential reaching law of variable coefficients, the sliding mode controller achieves the best balance between the dynamic quality and stability of the system. This sliding mode control method ensures that the wind turbine transmission chain system can quickly return to a balanced state when subjected to external disturbances, thereby reducing the vibration of the system.

[0025] B. A harmonic suppression mechanism is introduced to deal with the time harmonics and space harmonics caused by the inverter dead zone effect and manufacturing deviation in the permanent magnet synchronous generator. By adding a harmonic suppression algorithm to the current loop, the electromagnetic torque fluctuation is significantly reduced and the dynamic response performance of the wind turbine is improved;

[0026] C. The entire control system is composed of a sliding mode controller and an MPC controller. The sliding mode controller is mainly responsible for the rapid response and initial vibration reduction of the system, while the MPC controller further fine-tunes and suppresses the residual vibration caused by harmonics. The organic combination of the two makes the entire system have high dynamic response speed and strong robustness. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural schematic diagram of the wind turbine vibration control system;

[0028] Figure 2 It is the structure diagram of the exponential sliding mode controller with variable coefficients;

[0029] Figure 3 It is the block diagram of the predictive control of the wind power generation system model;

[0030] Figure 4 This is a comparison chart of the speed tracking effects of PI and SMC_MPC;

[0031] Figure 5 This is the vibration acceleration trend diagram of the parallel-stage high-speed wheel;

[0032] Figure 6 It is the trend diagram of the vibration displacement amplitude of the parallel-stage high-speed wheel;

[0033] Figure 7 This is the frequency domain analysis diagram of the parallel-stage high-speed wheel;

[0034] Figure 8 It is the frequency domain analysis diagram of the parallel stage high-speed wheel output torque. DETAILED DESCRIPTION

[0035] The present invention is further described below in conjunction with the embodiments, but it should not be understood that the above subject matter of the present invention is limited to the following embodiments. Without departing from the above technical ideas of the present invention, various substitutions and changes are made according to the common technical knowledge and customary means in the art, which should all be included in the protection scope of the present invention.

[0036] Embodiment 1:

[0037] This embodiment provides a method for active control of vibration reduction of large wind turbines. The speed loop in the machine-side rectifier in the electrical control system adopts variable structure sliding mode control, and the current loop adopts model predictive control. The variable structure sliding mode control method and the model predictive control method are combined to achieve vibration suppression and harmonic suppression of the wind turbine transmission system. Among them, the sliding mode control method is used to enhance the rapid response capability of the system under conditions of sudden changes in wind speed and reduce overshoot of speed and torque. The model predictive control method is used to optimize the control of the current loop and suppress harmonics in the system. Combine model predictive control with harmonic suppression. The model predictive control method is used in the current loop, and a harmonic suppression mechanism is introduced to suppress the harmonic problem in the motor and reduce electromagnetic torque fluctuations.

[0038] This embodiment provides a method combining variable structure sliding mode control and model predictive control to achieve vibration suppression and harmonic suppression of the wind turbine transmission system. Specifically, this embodiment combines variable structure sliding mode control (SMC) with model predictive control (MPC) to establish a comprehensive control system to cope with the vibration effects of wind speed mutations and electromagnetic torque fluctuations on wind turbines. Sliding mode control is used to enhance the system's rapid response capability under wind speed mutation conditions and reduce speed and torque overshoot, while model predictive control optimizes the control of the current loop and significantly suppresses harmonics in the system. Compared with traditional control methods, the control strategy of this embodiment has significant advantages in improving dynamic response speed, reducing electromagnetic torque fluctuations, and reducing mechanical system vibrations, thereby effectively improving the overall performance and reliability of wind turbines.

[0039] Embodiment 2:

[0040] This embodiment provides a large wind turbine vibration reduction active control system, including a communication module, a control module and a storage module. The communication module is connected to the electrical system for communication. The storage module is equipped with a sliding mode controller and a model prediction controller. The storage module stores execution instructions. The execution instructions are configured to execute the large wind turbine vibration reduction active control method described in Example 1 when executed by the control module.

[0041] Embodiment 3:

[0042] The main contents of this embodiment are the same as those of Embodiment 2, wherein the model predictive controller predicts and adjusts the control input in real time based on the value function and the rolling optimization method to ensure the optimal control effect of the system under complex working conditions.

[0043] Embodiment 4:

[0044] This embodiment provides a large wind turbine generator set, including the large wind turbine generator set vibration reduction active control system as described in Embodiment 2 or 3, as well as a transmission system and an electrical system. The electrical system responds to the control strategy instruction received from the control system, and the transmission system performs corresponding actions. The large wind turbine generator set realizes active vibration suppression of the transmission system through the electrical system, and realizes flexible adjustment and optimization control of the dynamic working conditions of the system.

[0045] Embodiment 5:

[0046] This embodiment is used to verify the significant effects of embodiments 1 to 4 in improving the dynamic performance and vibration reduction of wind turbines. This embodiment is based on the prototype data of an 8MW large wind turbine, and the wind speed under rated conditions is 10m / s. An aerodynamic sub-model, a mechanical transmission chain sub-model, a generator and control system sub-model, and a power grid sub-model are established: the aerodynamic sub-model is modeled using Betz theory. The mechanical transmission chain model includes an impeller, a main shaft, a gear transmission system, and a generator rotor. The impeller is modeled using a rotating cantilever beam, the main shaft is modeled using a variable-section hollow beam, the gear transmission system is modeled using a multi-degree-of-freedom model, and the generator rotor is modeled using a rotor model. A transmission system torsional vibration model is established in simulink. The generator is a medium-speed permanent magnet synchronous generator, and its control part adopts vector control. The power grid sub-model is established according to the power grid parameters given by the whole machine factory. Finally, each sub-model is connected through data transmission to form a complete wind turbine transmission chain machine-electronic control coupling model.

[0047] Figure 1 FIG. 1 is a schematic diagram of a wind turbine vibration control system according to an embodiment of the present application. Figure 1 As shown, the control system includes:

[0048] Sliding mode control: Figure 2 As shown in the figure, based on the variable coefficient exponential sliding mode control method, a sliding mode controller for the generator side rectifier speed loop control is designed to improve the dynamic response performance of the wind turbine under the condition of sudden wind speed changes. Based on the exponential reaching law, a variable coefficient exponential reaching law is designed, and its control law is:

[0049]

[0050] Among them, ε>0, k>0 are design parameters, x is the state of the system, and s is the sliding surface function. By designing a specific reaching law, the system can quickly return to the sliding surface when subjected to external disturbances and maintain the stability of the system.

[0051] Model predictive control: Model predictive control method is used in the current loop, such as Figure 3 As shown, the model predictive control method includes the following steps:

[0052] Establishment of prediction model: Discretize the motor model, rewrite the dq axis current into a form containing time variables, record the control period of the controller as T and make it small enough to establish the discrete prediction model of the motor.

[0053] Selection of value function: The value function is a constraint condition in model predictive control, which is used to set the judgment rule for predicting the optimal value. The value function is selected based on the established current prediction model. Take the predicted current at time k in the two-phase rotating coordinate system and the current reference current The difference is used as the evaluation index, and the final value function is as follows:

[0054]

[0055] in, Represents the predicted current. Indicates the reference current

[0056] Implementation of rolling optimization: Rolling optimization is performed through predictive models to adjust current control in real time to reduce the impact of harmonics.

[0057] Based on simulink, the Runge-Kutta algorithm is used to simulate and analyze the vibration response characteristics of the mechanical system. The wind conditions are set to 9.0 m / s during 0-30s, 10.5 m / s during 30-45s, and 10.0 m / s during 45-60s. The results of the generator speed response under the traditional control method PI and SMC_MPC control are as follows: Figure 4 Both control algorithms can track the reference speed well, but when the wind speed changes suddenly, the system responds faster, the steady-state time is shorter and the overshoot is very small under SMC_MPC control.

[0058] In order to more intuitively measure the vibration suppression effect of SMC_MPC control on the gear system, the simulation time is divided into five time periods of 25-30s, 30-33s, 40-45s, 45-48s, and 55-60s, corresponding to three time periods of steady wind speed and two time periods containing wind speed mutations. The vibration acceleration RMS value and vibration displacement amplitude of the parallel stage high-speed wheel under PI and SMC_MPC control in these five time periods are shown in Figure 2. Figure 5 , Figure 6 As shown in the figure, the RMS value of vibration acceleration in the stable operation stage decreased by 8.94%-36.09%, and the vibration displacement amplitude decreased by 7.34%-22.67%. The RMS value of vibration acceleration decreased by 9.26%-36.19% and the vibration displacement amplitude decreased by 19.31%-24.45% during the period of sudden wind speed change. In the five time periods, SMC_MPC control can effectively improve the vibration reduction capability and operation stability of the high-speed wheel.

[0059] Taking the frequency domain analysis of parallel-stage high-speed wheels as an example, the frequency domain analysis of vibration acceleration and output torque of parallel-stage high-speed wheels are shown in the following table. Figure 7 , Figure 8 As shown, the harmonics generated by the electromechanical system are mainly 6f i 、f 2m , 2f 2m 、f 3m 、f 3m ±f1m 、f 3m +5f H 、f 3m +f 2m , 2f 3m With 2f 3m +5f H The harmonics generated by the mechanical system are mainly f 2S 、f 1m 、f 2m , 2f 2m 、f 3m 、f 3m +5f H , 2f 3m , 2f 3m +5f H 、3f 3m With 3f 3m +5f H The amplitude of the combined frequency component formed by the meshing frequency of the transmission system is significantly reduced, and the combined harmonic component is suppressed.

[0060] This embodiment demonstrates the superior performance of wind turbines based on the SMC_MPC control strategy under complex working conditions. Compared with traditional PI control, SMC_MPC control not only improves the dynamic response speed of the system, reduces overshoot and steady-state error, but also significantly reduces the fluctuation of electromagnetic torque and achieves effective suppression of harmonics, thereby effectively reducing the vibration of the mechanical system and extending the service life of the wind turbine. Through this embodiment, it can be seen that the active control method combining variable structure sliding mode control with model predictive control has a significant effect in improving the dynamic performance and vibration reduction of wind turbines.

Claims

1. A large wind turbine active vibration reduction control method, characterized in that: An electrical control system for a wind turbine is established, in which the speed loop in the machine-side rectifier adopts variable structure sliding mode control, and the current loop adopts model predictive control; the sliding mode control method can enhance the system's rapid response capability under conditions of sudden wind speed changes and reduce overshoot of speed and torque; the model predictive control method can optimize the control of the current loop and suppress harmonics in the system.

2. A large-scale wind turbine active vibration reduction control method according to claim 1, characterized in that: Combine model predictive control with harmonic suppression; adopt model predictive control method in the machine-side rectifier current loop, and introduce harmonic suppression mechanism to suppress harmonic problems in the motor and reduce electromagnetic torque fluctuations.

3. A large wind turbine active vibration reduction control system, characterized in that: It comprises a communication module, a control module and a storage module; the communication module is connected to the electrical system for communication; the storage module is equipped with a sliding mode controller and a model prediction controller; the storage module stores execution instructions; the execution instructions are configured to be able to execute the large wind turbine active vibration reduction control method as claimed in claim 1 or 2 when executed by the control module.

4. A large-scale wind turbine active vibration reduction control system according to claim 3, characterized in that: The model predictive controller predicts and adjusts the control input in real time based on the value function and the rolling optimization method to ensure the optimal control effect of the system under complex working conditions.

5. A method for constructing a large wind turbine active vibration reduction control system according to claim 4, characterized in that: The following steps are involved: 1) Establish an electrical control system; Establish an electrical control system including generators and machine-side rectifiers; 2) Design a sliding mode controller; Based on the exponential sliding mode control method with variable coefficients, design a sliding mode controller for the generator side rectifier speed loop control to improve the dynamic response performance of the wind turbine under sudden changes in wind speed; the sliding mode controller is changed on the basis of the exponential reaching law, and a variable coefficient exponential reaching law is designed, and its control law is: Where ε>0, k>0 are design parameters, x is the state of the system, s is the sliding surface function, and by designing a specific reaching law, the system can quickly return to the sliding surface when subjected to external disturbances and maintain the stability of the system; 3) Designing a model predictive controller; Step 3) specifically includes the following sub-steps: 3.1) Establishment of prediction model: Discretize the motor model, rewrite the dq axis current into a form containing time variables, record the control period of the controller as T and make it small enough, and establish the discrete prediction model of the motor; 3.2) Selection of value function: The value function is a constraint condition in model predictive control, which is used to set the judgment rule for predicting the optimal value. The value function is selected based on the established current prediction model; the predicted current at time k in the two-phase rotating coordinate system is taken and the current reference current The difference is used as the evaluation index, and the final value function is as follows: in, represents the predicted current; Indicates the reference current 3.3) Implementation of rolling optimization: Rolling optimization is performed through the prediction model, and current control is adjusted in real time to reduce the impact of harmonics; 4) Controller parameter optimization: Optimize controller parameters through the simulation platform to ensure the synergy between the sliding mode controller and the model predictive controller, thereby achieving effective vibration reduction of the mechanical system of the wind turbine.

6. A large wind turbine generator set, characterized in that: It comprises the large wind turbine active vibration reduction control system as described in claim 3 or 4, as well as a transmission system and an electrical system; the electrical system responds to the control strategy instructions received from the control system, and the transmission system performs corresponding actions; the large wind turbine achieves active vibration suppression of the transmission system through the electrical system, and realizes flexible adjustment and optimal control of the system dynamic conditions.

7. A large wind turbine generator set according to claim 6, characterized in that: The transmission system includes an impeller, a main shaft, a gear transmission system and a generator.

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