A dynamic feedback linearization control method for a large wind turbine variable pitch actuator

Abstract

The application discloses a dynamic feedback linearization control method for a variable-pitch actuator of a large wind turbine, and belongs to the technical field of wind turbine control. The variable-pitch actuator is mainly composed of a variable-pitch motor and a driver thereof, a variable-pitch actuator controller and an encoder. * The given mechanical angle of the rotor of the variable-pitch motor is calculated, the given electromagnetic torque of the variable-pitch motor is calculated by using the dynamic feedback linearization method and is sent to the variable-pitch motor driver, the variable-pitch motor is controlled to work by the variable-pitch motor driver, and the variable-pitch control of the wind turbine is realized. Based on the above method, the adaptability of the variable-pitch control system of the wind turbine to different wind conditions and the suppression ability of the variable-pitch control system to external disturbances can be improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of variable pitch control of large wind turbine generators, and particularly relates to a dynamic feedback linearization control method for a variable pitch actuator of a large wind turbine generator. BACKGROUND

[0002] At present, most large wind turbine generators adopt variable pitch control. The variable pitch wind turbine generator has the advantages of stabilizing the output power of the generator through variable pitch control when the wind speed exceeds the rated value, obtaining the maximum starting torque of the generator through variable pitch adjustment when the generator starts, and having the aerodynamic brake function through variable pitch adjustment to make the blades to 90°.

[0003] However, the wind turbine generator is affected by various uncertain factors during operation, including random changes in wind speed and wind direction, changes in the blade self-gravity in the variable pitch direction during rotation of the wind wheel, differences in the self-mass distribution of different blades of the same generator, and differences in the parameters of the variable pitch actuator of the generator. These factors will cause differences in the transfer function of the variable pitch system of each blade of the generator, and the uncertainty caused by external interference and the complexity of the operating conditions of the wind turbine generator make it difficult to accurately model and control the variable pitch system of the wind turbine generator.

[0004] Chinese patent application CN201711291715.7 introduces the sliding mode control and neural network method into the feedback linearization control of the variable pitch system to improve the robustness and stability of the variable pitch control system, but the control algorithm is complex and the parameter tuning is difficult.

[0005] The article "Research on Variable Pitch Control of Wind Turbine Based on Feedback Linearization" (2011) uses state feedback linearization method to accurately feedback linearize the wind turbine model, obtains its global linearization model, and uses linear quadratic optimal control for pitch angle control. The article "Constant Power Feedback Linearization Control of Variable Pitch Wind Turbine Generator" (2012) establishes an affine nonlinear model of the wind turbine, uses differential geometric feedback linearization transformation to realize global accurate linearization, and designs a pitch angle controller according to the new linearization model. The methods used in the above documents improve the model to some extent and improve the variable pitch control performance and robustness, but the suppression ability of external interference and internal uncertain factors is still insufficient. SUMMARY

[0006] To address the challenges of accurately modeling large wind turbine pitch control systems and the complexity and uncertainties of their operation, this invention provides a dynamic feedback linearization control method for large wind turbine pitch control actuators. This method utilizes an extended state observer to estimate the impact of external disturbances and internal uncertainties on the pitch control system in real time, and compensates accordingly in the system's input control quantities. This approximates the pitch control system as a linear system. An error feedback control method is then used to design the control law for this linear system, thereby improving the dynamic response characteristics of the wind turbine pitch control system and enhancing the pitch control actuator's ability to track pitch angle commands from the wind turbine's main control system.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A dynamic feedback linearization control method for a pitch actuator of a large wind turbine is disclosed. The pitch actuator includes a pitch motor, a pitch motor driver, a pitch actuator controller, and an encoder. The pitch actuator controller controls the pitch angle β of the wind turbine's main control system. * Based on the actual mechanical angle θ of the pitch motor rotor, the electromagnetic torque setpoint of the pitch motor is calculated using a dynamic feedback linearization method. The data is then sent to the pitch motor driver, which controls the pitch motor to achieve pitch control of the wind turbine.

[0009] Furthermore, the dynamic equations of the variable pitch system In The term is considered as a whole and observed in real time using an extended state observer to obtain the observed value z. Simultaneously, the rate of change of the pitch angle β, dβ / dt, is derived from the extended state observer, where J... P T is the moment of inertia of the blade. e n represents the electromagnetic torque of the pitch motor. k For the gearbox shift ratio, T a k represents the components of the aerodynamic force and gravity acting on the blades in the pitch direction. l η is the damping coefficient of the variable pitch system, and η is the force exerted by other uncertain factors.

[0010] Furthermore, a tracking differentiator is used to calculate the pitch angle β of the wind turbine's main control system. * The differential signal dβ * / dt.

[0011] Furthermore, in the electromagnetic torque given by the pitch motor The dynamic equations of the variable pitch system, which are compensated in real time by the extended state observer, are as follows: The observed value z of the term, i.e., let The approximate linear equations of the dynamic equations of the variable pitch system are obtained.

[0012] Furthermore, the approximate linear equations of the dynamic equations of the variable pitch system are... The rate of change of pitch angle β, dβ / dt, obtained from the extended state observer, and the pitch angle β obtained from the tracking differentiator are combined. * The differential signal dβ * / dt, a linear controller is designed using the error feedback method, let u=k p ×(β * -β)+k i ×∫(β * -β)dt+k d ×(dβ * / dt-dβ / dt), where k p k i k d These are the proportional coefficient, integral coefficient, and derivative coefficient of the PID controller, respectively.

[0013] Furthermore, the electromagnetic torque of the pitch motor is given. Design according to the following expression: The information is then sent from the pitch actuator controller to the pitch motor driver to control the operation of the pitch motor.

[0014] Furthermore, the pitch motor is a permanent magnet synchronous motor or a DC motor.

[0015] Furthermore, the linear controller is a PID controller or a PI controller. The present invention has at least the following beneficial effects:

[0016] The wind turbine pitch control based on the dynamic feedback linearization method proposed in this invention can effectively control the wind turbine speed under different wind speed conditions such as step wind speed, gradual wind speed and random wind speed. It has good suppression ability against the influence of external interference and internal uncertainties, and has the advantages of small speed fluctuation, strong anti-interference ability, simple structure, easy parameter tuning and easy engineering implementation. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the pitch control mechanism for a wind turbine.

[0018] Figure 2 This is a schematic diagram of the dynamic feedback linearization control principle of the pitch actuator of a wind turbine. Detailed Implementation

[0019] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0020] like Figure 1As shown, the variable pitch actuator mainly includes: variable pitch motor, variable pitch motor driver, variable pitch actuator controller, encoder, etc. The variable pitch actuator controller receives the angle information θ of the variable pitch motor rotating shaft measured by the encoder, converts it into the actual pitch angle information β = θ / n of the unit blade k , n k is the gear ratio; at the same time, the electromagnetic torque given signal of the variable pitch motor is sent to the variable pitch motor driver, and the variable pitch motor driver controls the operation of the variable pitch motor.

[0021] As shown in Figure 2 , the dynamic feedback linearization control of the wind turbine variable pitch actuator is mainly realized through a tracking differentiator, a linear controller, an extended state observer, and a variable pitch motor driver and a variable pitch motor. The extended state observer is used to observe and compensate the possible external disturbances and internal uncertainties of the variable pitch actuator in real time; the tracking differentiator is used to process the pitch angle signal given by the unit main control system and extract the differential signal of the pitch angle; the linear controller combines the pitch angle signal given and its differential signal with the actual pitch angle signal and its differential signal given by the extended state observer, and performs feedback control on the linear system compensated by the extended state observer.

[0022] The specific implementation steps of the dynamic feedback linearization control method of the large-scale wind turbine variable pitch actuator of the present application are as follows:

[0023] Step 1: regarding the term of the variable pitch system dynamics equation as a whole, and using an extended state observer to observe it in real time, and obtaining the change rate dβ / dt of the pitch angle β from the extended state observer, wherein J P is the blade moment of inertia, T e is the electromagnetic torque of the variable pitch motor, n k is the gear ratio, T a is the force in the variable pitch direction of the aerodynamic force and gravity on the blade, k l is the damping coefficient of the variable pitch system, and η is the force of other uncertain factors.

[0024] Step 2: in the electromagnetic torque given of the variable pitch motor, compensate the observation value z of the term of the variable pitch system dynamics equation observed in real time by the extended state observer, i.e. let the electromagnetic torque given amount of the variable pitch motor be , and obtain the approximate linear equation of the variable pitch system dynamics equation

[0025] Step 3: use a tracking differentiator to calculate the pitch angle β given by the wind turbine main control system* the differential signal dβ * / dt; specifically, by using the steepest tracking differentiator, the differential value of the signal is reasonably extracted by quickly tracking the given signal, while the noise in the signal can be effectively suppressed.

[0026] Step 4: the approximate linear equation of the pitch system dynamics equation in step 2 combined with the change rate dβ / dt of the pitch angle β obtained by the extended state observer in step 1, and the differential signal dβ * / dt obtained by the tracking differentiator in step 3 * , a linear controller (PID controller or PI controller, etc.) is designed by using error feedback method, and u=k p ×(β * -β)+k i ×∫(β * -β)dt+k d ×(dβ * / dt-dβ / dt), where k p , k i , k d are the proportional coefficient, integral coefficient and differential coefficient of the PID controller respectively.

[0027] Step 5: the expression of the electromagnetic torque given of the pitch motor is obtained by combining step 2 and step 4 and is sent to the pitch motor driver by the pitch actuator controller to control the operation of the pitch motor and perform the pitch control of the unit.

[0028] Those skilled in the art will readily understand that the above description is only a preferred embodiment of the present application and is not intended to limit the present application, and any modifications, equivalent replacements and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application.​

Claims

1. A dynamic feedback linearization control method for a large wind turbine variable pitch actuator, characterized in that: The variable pitch actuator comprises a variable pitch motor, a variable pitch motor driver, a variable pitch actuator controller, and an encoder; the variable pitch actuator controller calculates an electromagnetic torque given value of the variable pitch motor according to a pitch angle of a wind turbine main control system , in combination with an actual mechanical angle of a variable pitch motor rotor , and sends the electromagnetic torque given value to the variable pitch motor driver, so that the variable pitch motor driver controls the variable pitch motor to work, thereby realizing variable pitch control of the wind turbine . The dynamic equations of the variable pitch system In The term is treated as a whole, and an extended state observer is used to observe it in real time to obtain the observed values. Simultaneously, the pitch angle is obtained from the extended state observer. rate of change ,in The moment of inertia of the blade. For the electromagnetic torque of the pitch motor, For gearbox shift ratios, This refers to the components of the aerodynamic force and gravity acting on the blades in the pitch direction. The damping coefficient of the variable pitch system is... The forces exerted by other uncertain factors; A tracking differentiator is used to calculate a differential signal of a pitch angle of a main control system of a wind turbine generator ;​ In the electromagnetic torque of the variable pitch motor is given Compensation of the observed value of the item in the variable pitch system dynamics equation observed in real time by the extended state observer That is, let The approximate linear equation of the variable pitch system dynamics equation is obtained ;​ approximate linear equation of the dynamic equation of the variable pitch system , the rate of change of the pitch angle obtained by combining an extended state observer and the differential signal of the pitch angle obtained by a tracking differentiator , a linear controller is designed by using error feedback method, so that , wherein , , are the proportional coefficient, integral coefficient and differential coefficient of the PID controller, respectively Electromagnetic torque of the pitch motor is designed as follows: and is sent to the pitch motor driver by the pitch actuator controller to control the pitch motor operation.

2. A dynamic feedback linearization control method of a variable pitch actuator of a large wind turbine generator unit as claimed in claim 1, characterized in that: The variable pitch motor is a permanent magnet synchronous motor or a direct current motor.

3. A dynamic feedback linearization control method of a large wind turbine variable pitch actuator as claimed in claim 1, characterized in that: The linear controller is a PID controller or a PI controller.

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