Method and device for suppressing low-frequency oscillation of doubly-fed fan based on pitch angle control and medium

Abstract

The invention discloses a double-fed fan low-frequency oscillation suppression method and device based on pitch angle control and a medium. The problem that local suppression of low-frequency oscillation cannot be effectively suppressed is solved. By monitoring the angular velocity difference value of a wind wheel shaft and a rotor shaft in real time, the coupling dynamic characteristics of pitch angle control and electromagnetic torque are directly captured, an additional damping controller is designed based on the inherent frequency of double mass blocks, and the output of the additional damping controller is superposed on the pitch angle control link of the doubly-fed unit. Optimized control over the coupling characteristic between the pitch angle control link and the unit output electromagnetic torque is achieved. And low-frequency oscillation suppression is carried out in a pitch angle control link, so that accurate suppression of a low-frequency oscillation source is realized. The balance relation between the electromagnetic torque and the mechanical torque is directly adjusted through rotor rotating speed compensation, when the wind speed suddenly changes or the power grid is disturbed, the controller can adjust the compensation value in a self-adaptive mode, the damping ratio of the system is increased, and the oscillation problem caused by the coupling characteristic is fundamentally avoided.

Description

Technical Field

[0001] The present application relates to the field of wind power generation, and in particular to a method, device and medium for suppressing low-frequency oscillation of a doubly-fed wind turbine based on pitch angle control. Background Art

[0002] In today's energy transition, the stable operation of doubly-fed wind farm systems, a key technology for integrating renewable energy into the grid, is crucial to the reliability and security of the power system. However, low-frequency oscillations in wind farms have long been a major challenge hindering the stable operation of these systems.

[0003] Traditional approaches often focus solely on the impact of low-frequency oscillations in wind farms on the power system and perform local optimizations. For example, these approaches employ direct-drive turbines as system power oscillation suppressors to suppress oscillations by optimizing the parameters of the Power Oscillation Damping Controller (POD). However, this approach ignores the fundamental cause of low-frequency oscillations in doubly-fed wind turbine grid-connected systems: the coupling between the pitch angle control link and the turbine's output electromagnetic torque. Therefore, it fails to fundamentally address the low-frequency oscillations. When the system is subject to external disturbances, such as changes in wind speed or grid operating conditions, this coupling relationship can cause low-frequency oscillations in the system. Low-frequency oscillations may still occur or even intensify, making it difficult to fundamentally address the low-frequency oscillations through local optimization alone.

[0004] It can be seen that how to fundamentally suppress low-frequency oscillation is a technical problem that needs to be solved urgently by people in this field. Summary of the Invention

[0005] The purpose of this application is to provide a method, device and medium for suppressing low-frequency oscillation of a doubly fed wind turbine based on pitch angle control, so as to solve the problem that local suppression of low-frequency oscillation cannot be effectively achieved.

[0006] To solve the above technical problems, the present application provides a method for suppressing low-frequency oscillation of a doubly-fed wind turbine based on pitch angle control, comprising:

[0007] Obtaining the rotor shaft angular velocity of the wind rotor shaft and the rotor shaft angular velocity of the rotor shaft;

[0008] Obtaining an angular velocity difference according to the wind wheel shaft angular velocity and the rotor shaft angular velocity;

[0009] Obtaining a controller transfer function of an additional damping controller according to the natural low-frequency oscillation frequency of the dual-mass block, the angular velocity difference, and the electromagnetic torque increment of the doubly-fed wind turbine generator set;

[0010] obtaining a rotor speed compensation value based on the angular velocity difference and the controller transfer function;

[0011] The rotor speed of the doubly-fed wind turbine generator is compensated and controlled based on the rotor speed compensation value.

[0012] As an optional solution, in the above-mentioned method for suppressing low-frequency oscillation of a doubly-fed wind turbine based on pitch angle control, before obtaining the rotor shaft angular velocity of the wind rotor shaft and the rotor shaft angular velocity, the method further includes:

[0013] Obtain the output active power of the doubly-fed wind turbine;

[0014] Determining whether the output active power fluctuates periodically within a preset threshold;

[0015] If so, it is determined that low-frequency oscillation is currently occurring, and the step of obtaining the rotor shaft angular velocity of the wind rotor shaft and the rotor shaft angular velocity of the rotor shaft is entered.

[0016] As an optional solution, in the above-mentioned method for suppressing low-frequency oscillation of a doubly-fed wind turbine based on pitch angle control, obtaining the natural low-frequency oscillation frequency of the dual-mass block includes:

[0017] The doubly-fed wind turbine generator set and the wind turbine connecting shaft are equivalent to a double mass block;

[0018] The inherent low-frequency oscillation frequency is obtained according to the physical parameters of the connecting shaft between the doubly-fed wind turbine generator set and the wind turbine.

[0019] As an optional solution, in the above-mentioned method for suppressing low-frequency oscillation of a doubly-fed wind turbine based on pitch angle control, obtaining the natural low-frequency oscillation frequency based on the physical parameters of the shaft connecting the doubly-fed wind turbine generator set and the wind turbine includes:

[0020] Obtaining the inertia time constant, stiffness coefficient, and system electrical angular velocity base value of the connecting shaft between the doubly-fed wind turbine generator set and the wind turbine;

[0021] Obtaining the natural low-frequency oscillation frequency according to the inertia time constant, stiffness coefficient, system electrical angular velocity base value and the first formula of the connecting shaft between the doubly-fed wind turbine generator set and the wind turbine;

[0022] The first formula is: ;

[0023] Where H t and H r are the inertia time constant of the wind turbine and the rotor inertia time constant of the doubly fed wind turbine generator set respectively; K m is the rigidity coefficient between the doubly-fed wind turbine generator set and the wind turbine connecting shaft; ω b is the base value of the system electrical angular velocity, ω osc represents the natural low frequency oscillation frequency.

[0024] As an optional solution, in the above-mentioned method for suppressing low-frequency oscillation of a doubly-fed wind turbine based on pitch angle control, obtaining the rotor shaft angular velocity of the wind rotor shaft and the rotor shaft angular velocity of the rotor shaft includes:

[0025] Collecting a wind wheel shaft speed pulse signal of the wind wheel shaft and a wind wheel shaft speed pulse signal of the rotor shaft;

[0026] performing filtering processing on the wind wheel shaft speed pulse signal and the rotor shaft speed pulse signal respectively;

[0027] The wind wheel shaft speed is obtained according to the wind wheel shaft speed pulse signal and the preset number of pulses per revolution, and the rotor shaft speed is obtained according to the rotor shaft speed pulse signal and the preset number of pulses per revolution;

[0028] The wind wheel shaft angular velocity and the rotor shaft angular velocity are obtained according to the wind wheel shaft rotational speed and the rotor shaft rotational speed.

[0029] As an optional solution, in the above-mentioned method for suppressing low-frequency oscillation of a doubly-fed wind turbine based on pitch angle control, the controller transfer function of the additional damping controller is obtained according to the natural low-frequency oscillation frequency of the dual mass block and the angular velocity difference, including:

[0030] Obtaining the natural low-frequency oscillation frequency of the dual-mass block;

[0031] Establishing a transfer function of the damping torque coefficient between the electromagnetic torque increment of the doubly-fed wind turbine generator set and the angular velocity difference;

[0032] Obtaining a phase characteristic at the natural low-frequency oscillation frequency based on a transfer function expression of the damping torque coefficient, and obtaining a phase compensation phase angle;

[0033] A controller transfer function of the additional damping controller is obtained according to the phase compensation phase angle.

[0034] As an optional solution, in the above-mentioned method for suppressing low-frequency oscillation of a doubly-fed wind turbine based on pitch angle control, the compensating control of the rotor speed of the doubly-fed wind turbine based on the rotor speed compensation value includes:

[0035] Obtaining a preset rotor reference angular velocity;

[0036] Obtaining a speed compensation result according to the rotor speed compensation value, the preset rotor reference angular velocity, and the rotor shaft angular velocity;

[0037] The speed compensation result is input into the PI controller.

[0038] To solve the above technical problems, the present application further provides a low-frequency oscillation suppression device for a doubly-fed wind turbine based on pitch angle control, comprising:

[0039] An acquisition module, configured to acquire the rotor shaft angular velocity of the wind rotor shaft and the rotor shaft angular velocity of the rotor shaft;

[0040] a calculation module, configured to obtain an angular velocity difference according to the angular velocity of the wind wheel shaft and the angular velocity of the rotor shaft;

[0041] an analysis module, configured to obtain a controller transfer function of an additional damping controller according to the natural low-frequency oscillation frequency of the dual-mass block, the angular velocity difference, and the electromagnetic torque increment of the doubly-fed wind turbine generator set;

[0042] an output module, configured to obtain a rotor speed compensation value based on the angular velocity difference and the controller transfer function;

[0043] The compensation module is used to perform compensation control on the rotor speed of the doubly-fed wind turbine based on the rotor speed compensation value.

[0044] To solve the above technical problems, the present application further provides a low-frequency oscillation suppression device for a doubly-fed wind turbine based on pitch angle control, comprising:

[0045] memory for storing computer programs;

[0046] The processor is configured to implement the steps of the above-mentioned method for suppressing low-frequency oscillation of a doubly-fed wind turbine based on pitch angle control when executing the computer program.

[0047] In order to solve the above technical problems, the present application also provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the above-mentioned method for suppressing low-frequency oscillation of a doubly fed wind turbine based on pitch angle control are implemented.

[0048] The low-frequency oscillation suppression method of a doubly fed wind turbine based on pitch angle control provided by the present application directly captures the coupling dynamic characteristics of pitch angle control and electromagnetic torque by real-time monitoring of the angular velocity difference between the wind wheel shaft and the rotor shaft, and designs an additional damping controller based on the natural frequency of the dual-mass block, and superimposes its output on the pitch angle control link of the doubly fed unit, thereby achieving optimized control of the coupling characteristics between the pitch angle control link and the output electromagnetic torque of the unit. Low-frequency oscillation suppression is performed in the pitch angle control link to achieve precise suppression of the source of low-frequency oscillation. Compared with traditional local optimization methods, the present application directly adjusts the balance relationship between electromagnetic torque and mechanical torque through rotor speed compensation, effectively cutting off the transmission path of oscillation energy. When the wind speed suddenly changes or the power grid is disturbed, the controller can adaptively adjust the compensation value, significantly improve the system damping ratio, and fundamentally avoid the problem of oscillation deterioration caused by coupling characteristics.

[0049] In addition, the present application also provides a device and a medium, which correspond to the above-mentioned method for suppressing low-frequency oscillation of a doubly-fed wind turbine based on pitch angle control, and have the same effect as above. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0051] Figure 1 A flowchart of a method for suppressing low-frequency oscillation of a doubly-fed wind turbine based on pitch angle control is provided for an embodiment of the present application;

[0052] Figure 2 A schematic diagram of a low-frequency oscillation suppression process is provided for an embodiment of the present application;

[0053] FIG3( a ) is a schematic diagram of a principle for providing positive damping according to an embodiment of the present application;

[0054] FIG3( b ) is a schematic diagram of a principle of providing negative damping according to an embodiment of the present application;

[0055] Figure 4 A schematic diagram of the change in damping ratio before and after suppressing low-frequency oscillation provided by an embodiment of the present application;

[0056] Figure 5 A structural diagram of a low-frequency oscillation suppression device for a doubly-fed wind turbine based on pitch angle control provided in an embodiment of the present application;

[0057] Figure 6 This is a structural diagram of another low-frequency oscillation suppression device for a doubly-fed wind turbine based on pitch angle control provided in an embodiment of the present application. DETAILED DESCRIPTION

[0058] The following will be combined with the accompanying drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0059] The core of this application is to provide a method, device and medium for suppressing low-frequency oscillation of a doubly fed wind turbine based on pitch angle control.

[0060] In order to enable those skilled in the art to better understand the present application, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0061] To solve the above problems, the present invention provides a method for suppressing low-frequency oscillation of a doubly-fed wind turbine based on pitch angle control. Figure 1 A flowchart of a method for suppressing low-frequency oscillation of a doubly fed wind turbine based on pitch angle control is provided for an embodiment of the present application. Figure 1 As shown, including:

[0062] S11: Obtaining the rotor shaft angular velocity of the wind rotor shaft and the rotor shaft angular velocity of the rotor shaft;

[0063] S12: Obtaining an angular velocity difference according to the angular velocity of the wind wheel shaft and the angular velocity of the rotor shaft;

[0064] S13: obtaining a controller transfer function of the additional damping controller according to the natural low-frequency oscillation frequency of the dual-mass block, the angular velocity difference, and the electromagnetic torque increment of the doubly-fed wind turbine generator set;

[0065] S14: Obtaining a rotor speed compensation value based on the angular velocity difference and the controller transfer function;

[0066] S15: Compensating and controlling the rotor speed of the doubly-fed wind turbine generator based on the rotor speed compensation value.

[0067] Step S11 uses high-precision sensors to obtain the angular velocity of the rotor and rotor shafts of a doubly fed induction generator (DFIG). These sensors are typically speed encoders or angular velocity sensors installed on the rotor and rotor shafts. These sensors can use incremental or absolute encoders to provide highly accurate speed signals. The sensors should be installed at strategic locations on the rotor and rotor shafts to ensure signal accuracy and reliability. The acquired speed signals are typically pulsed and require filtering by a signal processing unit (e.g., a filter) to eliminate high-frequency noise and ensure signal smoothness and accuracy.

[0068] In this step, the angular velocity of the wind wheel shaft and the rotor shaft is accurately measured to ensure the accuracy of subsequent calculations. This step is performed immediately after the system is started to ensure the real-time and accuracy of the data.

[0069] Step S12 obtains the angular velocity difference according to the wind wheel shaft angular velocity and the rotor shaft angular velocity, and calculates the angular velocity difference Δω Δ It can be calculated by simple subtraction, that is, Δω Δ =ω t -ω r , where ω t is the angular velocity of the wind wheel shaft, ω ris the rotor shaft angular velocity. The angular velocity difference calculation should be performed in real time to ensure that it can promptly reflect the dynamic changes of the system. The calculated angular velocity difference can be further processed, such as smoothing or trend analysis, to improve data usability.

[0070] Since the change of angular velocity difference is closely related to low-frequency oscillation, it is chosen to calculate the angular velocity difference in real time during system operation so as to detect and suppress oscillation in time.

[0071] Step S13 determines the controller transfer function of the added damping controller based on the dual-mass natural low-frequency oscillation frequency, the angular velocity difference, and the electromagnetic torque increment of the doubly-fed wind turbine generator set. In this step, the doubly-fed wind turbine generator set and the wind turbine connecting shaft are treated as equivalent to a dual-mass system. Specifically, the wind wheel and generator rotor are each treated as two masses connected by springs and dampers to simulate the dynamic characteristics of an actual system. By analyzing the parameters of the dual-mass system (such as mass, damping coefficient, and stiffness), the system's natural low-frequency oscillation frequency is calculated. These parameters can be obtained through experimental measurement or theoretical analysis.

[0072] Analyze the amplitude and phase characteristics of the transfer function of the damping torque coefficient near the low-frequency oscillation frequency. These characteristics determine the dynamic response behavior of the system near the low-frequency oscillation frequency. Further design the controller transfer function of the additional damping controller. Based on the phase characteristics of the controller transfer function, design the phase compensation of the additional damping controller to ensure sufficient phase margin at the low-frequency oscillation frequency. Based on the amplitude characteristics of the transfer function of the damping torque coefficient, adjust the gain of the additional damping controller to ensure sufficient damping at the low-frequency oscillation frequency. To prevent the DC component from affecting the control effect, design a DC isolation link to ensure the controller's sensitivity to low-frequency oscillation signals.

[0073] In this way, the projection of the electromagnetic torque increment on the negative direction of the angular velocity difference increment can be effectively increased, thereby improving the damping ratio of the system and suppressing low-frequency oscillations.

[0074] Step S14 obtains a rotor speed compensation value based on the angular velocity difference and the controller transfer function, and processes the angular velocity difference through the controller transfer function of the additional damping controller to obtain a rotor speed compensation value. r_ref It can be calculated by the following formula: r_ref =G Pa (s)Δω Δ Here, G Pa (s) is the controller transfer function of the additional damping controller, Δω Δ is the angular velocity difference.

[0075] The rotor speed compensation value must be calculated in real time to ensure timely adjustment of the rotor speed. The calculated rotor speed compensation value can be further processed, such as limiting or filtering, to improve data availability and reliability.

[0076] In this step, by accurately calculating the rotor speed compensation value, the rotor speed can be dynamically adjusted to ensure stable system operation under different operating conditions. Because the rotor speed compensation value directly affects the dynamic response of the system, it is calculated immediately after the real-time calculation of the angular velocity difference to achieve fast and effective control.

[0077] Finally, step S15 performs compensation control on the rotor speed of the doubly fed wind turbine generator based on the rotor speed compensation value, and the calculated rotor speed compensation value ω is r_ref It is superimposed on the pitch angle control link of the doubly fed wind turbine to achieve compensation control of the rotor speed. Specifically: the pitch angle control link is selected as the implementation point of the compensation control, because the pitch angle control link is the key control link of the doubly fed wind turbine and can directly affect the rotor speed. The rotor speed compensation value ω r_ref It is superimposed on the input signal of the pitch angle control link, and the rotor speed is changed by adjusting the pitch angle, thereby suppressing low-frequency oscillation. Figure 2 As shown, the controller transfer function G of the additional damping controller is pa (s) is the angular velocity difference Δω Δ The input is the rotor speed compensation value ω of DFIG. r_ref The compensation is superimposed on the input of the proportional integral (PI) controller in the pitch angle control link. Figure 2 Chinese t is the angular velocity of the wind wheel shaft of the dual mass block, ω r is the angular velocity of the rotor shaft of the DFIG. ω* r According to the optimal tip speed ratio λ opt0 Set the DFIG rotor reference angular velocity. The PI controller is built into the pitch angle control link, and the PI controller outputs the pitch angle control reference value β * PI controller has a limiting link, variable β max The upper limit of the output β* is 0, and the lower limit is 0.

[0078] β* is subtracted from β by the adder (β * -β), and the result is used as the integral link "1 / T β s”, where β represents the actual value of the pitch angle output by the pitch angle control link, that is, the output of the integral link. βThe pitch angle is used to control the inertia time constant that characterizes the system delay characteristics. There is also a limit in the integral link, the variable β max As the upper limit of output β, β min as the lower limit value.

[0079] That is, this application uses the rotor reference angular velocity ω* r and the DFIG's rotor shaft angular velocity ω r After making the difference, add the rotor speed compensation value ω r_ref The obtained result is input into the PI controller in the pitch angle control link.

[0080] In this step, by superimposing the rotor speed compensation value on the pitch angle control link, the overall optimization control of the system can be achieved.

[0081] FIG3(a) is a schematic diagram of the principle of providing positive damping provided by an embodiment of the present application, and FIG3(b) is a schematic diagram of the principle of providing negative damping provided by an embodiment of the present application. As shown in FIG3(a) and FIG3(b), the pitch angle control system is increased by the angular velocity difference Δω. Δ The oscillation suppression control link of the input quantity makes the DFIG electromagnetic torque increment ΔT e The angular velocity difference Δω Δ The projection in the negative direction increases, corresponding to Figure 3(a), thereby increasing the low-frequency oscillation damping.

[0082] The electromagnetic torque increment ΔT of the doubly fed generator is known e and the angular velocity difference Δω Δ The transfer function of the damping torque coefficient between is G(s), and the controller transfer function of the additional damping controller is G pa (s). The addition of this control link brings the new electromagnetic damping torque coefficient D to the system e_β for:

[0083] ;

[0084] Where Re() represents the operation of taking the real part of the complex number; j represents the imaginary part in the complex frequency domain, ω osc is the natural frequency of low-frequency oscillation, G(jω osc ) is the inherent characteristic of the system, which represents the transfer function of the damping torque coefficient in ω osc The phase at G pa (jω osc ) represents the controller transfer function in ω osc The controller transfer function G of the additional damping controller is set by the above principle. pa (s), the newly added electromagnetic damping torque coefficient is less than zero, and ΔT is increased e The angular velocity difference Δω ΔThe projection in the negative direction further improves the low-frequency oscillation damping ratio.

[0085] The low-frequency oscillation suppression method of a doubly fed wind turbine based on pitch angle control provided by the embodiment of the present application directly captures the coupling dynamic characteristics of the pitch angle control and the electromagnetic torque by real-time monitoring of the angular velocity difference between the wind wheel shaft and the rotor shaft, and designs an additional damping controller based on the natural frequency of the dual-mass block, and superimposes its output on the pitch angle control link of the doubly fed unit, thereby achieving optimized control of the coupling characteristics between the pitch angle control link and the output electromagnetic torque of the unit. Low-frequency oscillation suppression is performed in the pitch angle control link to achieve precise suppression of the source of low-frequency oscillation. Compared with traditional local optimization methods, the present application directly adjusts the balance relationship between electromagnetic torque and mechanical torque through rotor speed compensation, effectively cutting off the transmission path of oscillation energy. When the wind speed suddenly changes or the power grid is disturbed, the controller can adaptively adjust the compensation value, significantly improve the system damping ratio, and fundamentally avoid the problem of oscillation deterioration caused by coupling characteristics.

[0086] Furthermore, specifically, the method for suppressing low-frequency oscillation of a doubly-fed wind turbine based on pitch angle control further includes, before obtaining the rotor shaft angular velocity of the wind rotor shaft and the rotor shaft angular velocity:

[0087] Obtain the output active power of the doubly-fed wind turbine;

[0088] Determining whether the output active power fluctuates periodically within a preset threshold;

[0089] If so, it is determined that low-frequency oscillation is currently occurring, and the step of obtaining the rotor shaft angular velocity of the wind rotor shaft and the rotor shaft angular velocity of the rotor shaft is entered.

[0090] The periodic fluctuation of active power is a significant feature of low-frequency oscillation, so it is chosen to monitor active power in real time during system operation to detect low-frequency oscillation in a timely manner.

[0091] This embodiment first obtains the output active power of the doubly-fed wind turbine, and then determines whether the active power fluctuates periodically within a preset threshold. Specifically, the output active power of the doubly-fed wind turbine is obtained in real time by a power sensor installed at the output end of the doubly-fed wind turbine.

[0092] Set a preset threshold range, such as ±5% of rated power, to determine whether the output active power fluctuates periodically within this range. If periodic fluctuations in active power are detected within the preset threshold, it can be preliminarily determined that the system has experienced low-frequency oscillation. For example, if the system output power fluctuates periodically between 0.1Hz and 2.5Hz, it can be determined that the system has experienced low-frequency oscillation.

[0093] Once the occurrence of low-frequency oscillation is determined, the step of obtaining the angular velocity of the wind wheel shaft and the rotor shaft is immediately entered for further analysis and processing.

[0094] In this embodiment, by monitoring the active power output of the doubly-fed wind turbine in real time and determining whether it fluctuates periodically within a preset threshold, the occurrence of low-frequency oscillations can be quickly and accurately detected. This method can promptly detect anomalies in the early stages of low-frequency oscillations, preventing further spread and intensification of the oscillations, thereby improving system stability and reliability.

[0095] According to the above embodiment, further, specifically, a method for suppressing low-frequency oscillation of a doubly-fed wind turbine based on pitch angle control, obtaining the natural low-frequency oscillation frequency of the dual-mass block, includes:

[0096] The doubly-fed wind turbine generator set and the wind turbine connecting shaft are equivalent to a double mass block;

[0097] The inherent low-frequency oscillation frequency is obtained according to the physical parameters of the connecting shaft between the doubly-fed wind turbine generator set and the wind turbine.

[0098] The doubly-fed wind turbine generator set and the wind turbine connecting shaft are equivalent to a dual-mass system. The specific equivalent method is as follows: Mass 1: represents the wind rotor, with its mass equal to the rotor's mass and moment of inertia equal to the rotor's moment of inertia. Mass 2: represents the generator rotor, with its mass equal to the rotor's mass and moment of inertia equal to the rotor's moment of inertia.

[0099] The coupling relationship between the wind turbine and the generator rotor is simulated by connecting the two masses via a spring and a damper. The spring stiffness coefficient and the damping coefficient of the damper can be obtained through experimental measurement or theoretical analysis.

[0100] Obtain the physical parameters of the shaft connecting the doubly-fed wind turbine generator set to the wind turbine, including but not limited to: Mass: The mass of the rotor and generator rotor. Moment of inertia: The moment of inertia of the rotor and generator rotor. Stiffness coefficient: The stiffness coefficient of the connecting spring. Damping coefficient: The damping coefficient of the connecting damper, used to calculate the natural low-frequency oscillation frequency.

[0101] Specifically, the method for suppressing low-frequency oscillation of a doubly-fed wind turbine based on pitch angle control, wherein the inherent low-frequency oscillation frequency is obtained according to the physical parameters of the connecting shaft between the doubly-fed wind turbine generator set and the wind turbine, comprises:

[0102] Obtaining the inertia time constant, stiffness coefficient, and system electrical angular velocity base value of the connecting shaft between the doubly-fed wind turbine generator set and the wind turbine;

[0103] Obtaining the natural low-frequency oscillation frequency according to the inertia time constant, stiffness coefficient, system electrical angular velocity base value and the first formula of the connecting shaft between the doubly-fed wind turbine generator set and the wind turbine;

[0104] The first formula is: ;

[0105] Where H t and H r are the inertia time constant of the wind turbine and the rotor inertia time constant of the doubly fed wind turbine generator set respectively; K m is the rigidity coefficient between the doubly-fed wind turbine generator set and the wind turbine connecting shaft; ω b is the base value of the system electrical angular velocity, ω osc represents the natural low frequency oscillation frequency.

[0106] The inertia time constant reflects the inertial characteristics of the system and can be calculated from the system's moment of inertia and rated power. The stiffness coefficient reflects the coupling stiffness between the wind turbine and the generator rotor and can be determined through experimental measurement or theoretical analysis. The system electrical angular velocity base is the system's reference angular velocity, typically the system's rated angular velocity.

[0107] It should be noted that this embodiment also provides a low-frequency oscillation frequency calculation formula:

[0108] ;

[0109] Among them, K e It is the synchronous torque coefficient obtained by the complex torque coefficient method, which is not an actual parameter. In fact, K e The influence on the low-frequency oscillation frequency of the system is relatively small, so the natural low-frequency oscillation frequency is usually calculated using the first formula.

[0110] Based on these physical parameters, the natural low-frequency oscillation frequency can be calculated using the first formula, accurately determining the system's natural oscillation characteristics. This method provides an accurate frequency reference when designing an added damping controller, ensuring that the controller provides sufficient damping at critical frequencies to effectively suppress low-frequency oscillations.

[0111] According to the above embodiment, specifically, the method for suppressing low-frequency oscillation of a doubly-fed wind turbine based on pitch angle control, obtaining the rotor shaft angular velocity of the wind rotor shaft and the rotor shaft angular velocity of the rotor shaft, includes:

[0112] Collecting a wind wheel shaft speed pulse signal of the wind wheel shaft and a wind wheel shaft speed pulse signal of the rotor shaft;

[0113] performing filtering processing on the wind wheel shaft speed pulse signal and the rotor shaft speed pulse signal respectively;

[0114] The wind wheel shaft speed is obtained according to the wind wheel shaft speed pulse signal and the preset number of pulses per revolution, and the rotor shaft speed is obtained according to the rotor shaft speed pulse signal and the preset number of pulses per revolution;

[0115] The wind wheel shaft angular velocity and the rotor shaft angular velocity are obtained according to the wind wheel shaft rotational speed and the rotor shaft rotational speed.

[0116] High-precision sensors (such as incremental encoders or absolute encoders) are used to collect speed pulse signals from the wind rotor and rotor shafts. These sensors are installed at key locations on the wind rotor and rotor shafts to ensure signal accuracy and reliability.

[0117] Wind rotor shaft speed pulse signal: Collect the wind rotor shaft speed pulse signal and filter it to eliminate high-frequency noise and ensure signal smoothness and accuracy. A low-pass filter can be used for filtering.

[0118] The wind wheel shaft speed pulse signal and the rotor shaft speed pulse signal are filtered, and the speeds of the wind wheel shaft and the rotor shaft are calculated based on the filtered speed pulse signals and the preset pulses per revolution (PPR).

[0119] The rotor shaft speed is calculated by dividing the number of pulses per revolution by the number of pulses per revolution. Similarly, the rotor shaft speed is calculated by dividing the number of pulses per revolution by the number of pulses per revolution. Each speed is then converted to angular velocity in radians per second (rad / s). The relationship between angular velocity ω and speed is ω = 2π × speed.

[0120] In this step, by accurately collecting and processing the speed pulse signals and calculating the angular velocity of the wind wheel and rotor shafts, we ensure the accuracy of subsequent calculations and provide reliable data support for suppressing low-frequency oscillations. Because accurate angular velocity measurement is the foundation of all subsequent calculations, this step is performed immediately after system startup to ensure real-time data accuracy.

[0121] According to the above embodiment, specifically, the controller transfer function of the additional damping controller is obtained according to the natural low-frequency oscillation frequency of the dual-mass block and the angular velocity difference, including:

[0122] Obtaining the natural low-frequency oscillation frequency of the dual-mass block;

[0123] Establishing a transfer function of the damping torque coefficient between the electromagnetic torque increment of the doubly-fed wind turbine generator set and the angular velocity difference;

[0124] Obtaining a phase characteristic at the natural low-frequency oscillation frequency based on a transfer function of the damping torque coefficient, and obtaining a phase compensation phase angle;

[0125] A controller transfer function of the additional damping controller is obtained according to the phase compensation phase angle.

[0126] By analyzing the physical parameters of the dual-mass system (such as inertia time constant, stiffness coefficient, etc.), the system's natural low-frequency oscillation frequency is calculated, and the electromagnetic torque increment ΔT of the doubly fed wind turbine generator set is established. eand the angular velocity difference Δω Δ The transfer function expression G(s) of the damping torque coefficient between the two can be obtained. A specific method may include: collecting system input and output data, such as angular velocity difference and electromagnetic torque increment, under actual operating conditions. Using a system identification algorithm (such as the least squares method or recursive least squares method), the collected data is fitted to obtain the parameters of the transfer function expression G(s) of the damping torque coefficient.

[0127] Analyze the transfer function expression of the damping torque coefficient G(s) at the natural low-frequency oscillation frequency ω osc The phase characteristics at ω are analyzed using the frequency domain analysis method to calculate the required phase compensation angle to ensure that osc Provides sufficient phase margin.

[0128] According to the amplitude-phase characteristics obtained in the above steps and the design principle of the additional damping controller, the parameters of the phase compensation, gain and DC isolation link of the additional damping controller are determined, and the controller transfer function G of the additional damping controller is further determined. Pa (s) is:

[0129] ;

[0130] Among them, G pac (s), G pai (s), K pad They are phase compensation term, DC isolation term, gain term, T pa1 、T pa2 are the leading and lagging correction time constants, T paw is the time constant of the DC isolation link, and s is the Laplace operator.

[0131] Through the above scheme, the controller transfer function G of the additional damping controller that provides sufficient phase compensation and damping at the natural low-frequency oscillation frequency is designed. Pa (s).

[0132] According to the above embodiment, specifically, the compensating control of the rotor speed of the doubly-fed wind turbine generator based on the rotor speed compensation value includes:

[0133] Obtaining a preset rotor reference angular velocity;

[0134] Obtaining a speed compensation result according to the rotor speed compensation value, the preset rotor reference angular velocity, and the rotor shaft angular velocity;

[0135] The speed compensation result is input into the PI controller.

[0136] According to the above embodiment, this embodiment refers to setting the rotor reference angular velocity ω* r and DFIG rotor shaft angular velocity ωr After making the difference, add the rotor speed compensation value ω r_ref The resulting speed compensation result is fed into a PI controller. Through proportional and integral functions, the PI controller rapidly responds to speed errors, ensuring the generator's speed remains stable near the reference speed. This allows for dynamic adjustment of the doubly-fed wind turbine's rotor speed, effectively suppressing low-frequency oscillations and improving system stability and reliability.

[0137] Figure 4 A schematic diagram of the change in damping ratio before and after suppressing low-frequency oscillation provided in an embodiment of the present application is shown in FIG. Figure 4 As shown in the figure, when the doubly fed wind power grid-connected system was disturbed by a three-phase short circuit fault at 5 seconds, the system experienced low-frequency oscillation. However, after adopting the suppression method based on pitch angle control proposed in this application, the damping ratio ξ of the system low-frequency oscillation mode increased from 0.0095 to 0.0235, effectively improving the damping characteristics of the doubly fed wind farm low-frequency oscillation. At the same time, the rotor shaft angular velocity ω of the doubly fed unit r , output active power P g The amplitude of the connecting shaft torsion angle θ is significantly reduced, and the steady state is reached again in a shorter time, which shows that the control strategy proposed in the present invention fundamentally improves the damping ratio of the low-frequency oscillation of the doubly fed wind farm and effectively suppresses the low-frequency oscillation of the doubly fed wind power grid-connected system.

[0138] In the above embodiments, a method for suppressing low-frequency oscillations of a doubly-fed wind turbine based on pitch angle control is described in detail. This application also provides corresponding embodiments of a device for suppressing low-frequency oscillations of a doubly-fed wind turbine based on pitch angle control. It should be noted that this application describes embodiments of the device from two perspectives: one from a functional module perspective and the other from a hardware perspective.

[0139] Based on the perspective of functional modules, Figure 5 The structure diagram of a low-frequency oscillation suppression device for a doubly fed wind turbine based on pitch angle control provided in an embodiment of the present application is as follows: Figure 5 As shown, a low-frequency oscillation suppression device for a doubly-fed wind turbine based on pitch angle control includes: an acquisition module 21 for acquiring a rotor shaft angular velocity of a wind rotor shaft and a rotor shaft angular velocity of a rotor shaft;

[0140] A calculation module 22, configured to obtain an angular velocity difference according to the wind wheel shaft angular velocity and the rotor shaft angular velocity;

[0141] an analysis module 23, configured to obtain a controller transfer function of the additional damping controller according to the natural low-frequency oscillation frequency of the dual-mass block, the angular velocity difference, and the electromagnetic torque increment of the doubly-fed wind turbine generator set;

[0142] an output module 24, configured to obtain a rotor speed compensation value based on the angular velocity difference and the controller transfer function;

[0143] The compensation module 25 is configured to perform compensation control on the rotor speed of the doubly-fed wind turbine generator based on the rotor speed compensation value.

[0144] Since the embodiments of the apparatus part correspond to the embodiments of the method part, please refer to the description of the embodiments of the method part for the embodiments of the apparatus part, and they will not be repeated here.

[0145] Figure 6 A structural diagram of another low-frequency oscillation suppression device for a doubly fed wind turbine based on pitch angle control provided in an embodiment of the present application is shown in FIG. Figure 6 As shown, the low-frequency oscillation suppression device of a doubly-fed wind turbine based on pitch angle control includes: a memory 30 for storing a computer program;

[0146] The processor 31 is configured to implement the steps of the method for obtaining user operation habit information in the above embodiment (method for suppressing low-frequency oscillation of a doubly-fed wind turbine based on pitch angle control) when executing a computer program.

[0147] The low-frequency oscillation suppression device for a doubly-fed wind turbine based on pitch angle control provided in this embodiment may include but is not limited to a mobile terminal, a personal computer, a workstation, and the like.

[0148] The processor 31 may include one or more processing cores, such as a quad-core processor or an octa-core processor. The processor 31 may be implemented in at least one of the following hardware forms: a digital signal processor (DSP), a field-programmable gate array (FPGA), or a programmable logic array (PLA). The processor 31 may also include a main processor and a coprocessor. The main processor is used to process data in the awake state, also known as a central processing unit (CPU); the coprocessor is a low-power processor used to process data in the standby state. In some embodiments, the processor 31 may be integrated with a graphics processing unit (GPU), which is responsible for rendering and drawing content required to be displayed on the display screen. In some embodiments, the processor 31 may also include an artificial intelligence (AI) processor, which is used to handle computational operations related to machine learning.

[0149] The memory 30 may include one or more computer-readable storage media, which may be non-transitory. The memory 30 may also include a high-speed random access memory, and a non-volatile memory, such as one or more disk storage devices, flash memory storage devices. In this embodiment, the memory 30 is at least used to store the following computer program 301, wherein, after the computer program is loaded and executed by the processor 31, it can implement the relevant steps of the method for suppressing low-frequency oscillation of a doubly fed wind turbine based on pitch angle control disclosed in any of the aforementioned embodiments. In addition, the resources stored in the memory 30 may also include an operating system 302 and data 303, etc., and the storage method may be temporary storage or permanent storage. Among them, the operating system 302 may include Windows, Unix, Linux, etc. The data 303 may include but is not limited to data involved in implementing the method for suppressing low-frequency oscillation of a doubly fed wind turbine based on pitch angle control.

[0150] In some embodiments, the low-frequency oscillation suppression device for a doubly-fed wind turbine based on pitch angle control may further include a display screen 32 , an input / output interface 33 , a communication interface 34 , a power supply 35 , and a communication bus 36 .

[0151] Those skilled in the art will understand that Figure 6 The structure shown in the figure does not constitute a limitation on the low-frequency oscillation suppression device of a doubly-fed wind turbine based on pitch angle control, and may include more or fewer components than those shown in the figure.

[0152] The embodiment of the present application provides a doubly fed wind turbine low-frequency oscillation suppression device based on pitch angle control, including a memory and a processor. When the processor executes the program stored in the memory, it can implement the following method: a doubly fed wind turbine low-frequency oscillation suppression method based on pitch angle control.

[0153] Finally, the present application also provides an embodiment corresponding to a computer-readable storage medium. The computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps described in the embodiment of the method for suppressing low-frequency oscillations of a doubly-fed wind turbine based on pitch angle control.

[0154] It is understandable that if the method in the above embodiment is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium and executes all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), disk or optical disk, and other media that can store program code.

[0155] The computer-readable storage medium provided in this embodiment stores a computer program. When a processor executes the program, the following method can be implemented: a method for suppressing low-frequency oscillation of a doubly-fed wind turbine based on pitch angle control.

[0156] The above is a detailed introduction to the method, device and medium for suppressing low-frequency oscillation of a doubly fed wind turbine based on pitch angle control provided by the present application. The various embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the various embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the scope of protection of the claims of the present application.

[0157] It should also be noted that, in this specification, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus comprising the element.

Claims

1. A method for suppressing low-frequency oscillation of a doubly-fed wind turbine based on pitch angle control, characterized in that: include: Obtaining the rotor shaft angular velocity of the wind rotor shaft and the rotor shaft angular velocity of the rotor shaft; Obtaining an angular velocity difference according to the wind wheel shaft angular velocity and the rotor shaft angular velocity; Obtaining a controller transfer function of an additional damping controller according to the natural low-frequency oscillation frequency of the dual-mass block, the angular velocity difference, and the electromagnetic torque increment of the doubly-fed wind turbine generator set; obtaining a rotor speed compensation value based on the angular velocity difference and the controller transfer function; The rotor speed of the doubly-fed wind turbine generator is compensated and controlled based on the rotor speed compensation value.

2. The method for suppressing low-frequency oscillation of a doubly-fed wind turbine based on pitch angle control according to claim 1, characterized in that: Before obtaining the rotor shaft angular velocity of the wind rotor shaft and the rotor shaft angular velocity of the rotor shaft, the following steps are also included: Obtain the output active power of the doubly-fed wind turbine; Determining whether the output active power fluctuates periodically within a preset threshold; If so, it is determined that low-frequency oscillation is currently occurring, and the step of obtaining the rotor shaft angular velocity of the wind rotor shaft and the rotor shaft angular velocity of the rotor shaft is entered.

3. The method for suppressing low-frequency oscillation of a doubly-fed wind turbine based on pitch angle control according to claim 1, characterized in that: Obtain the natural low-frequency oscillation frequency of the dual-mass block, including: The doubly-fed wind turbine generator set and the wind turbine connecting shaft are equivalent to a double mass block; The inherent low-frequency oscillation frequency is obtained according to the physical parameters of the connecting shaft between the doubly-fed wind turbine generator set and the wind turbine.

4. The method for suppressing low-frequency oscillation of a doubly-fed wind turbine based on pitch angle control according to claim 3, characterized in that: The method of obtaining the natural low-frequency oscillation frequency according to the physical parameters of the connecting shaft between the doubly-fed wind turbine generator set and the wind turbine comprises: Obtaining the inertia time constant, stiffness coefficient, and system electrical angular velocity base value of the connecting shaft between the doubly-fed wind turbine generator set and the wind turbine; Obtaining the natural low-frequency oscillation frequency according to the inertia time constant, stiffness coefficient, system electrical angular velocity base value and the first formula of the connecting shaft between the doubly-fed wind turbine generator set and the wind turbine; The first formula is: ; Where H t and H r are the inertia time constant of the wind turbine and the rotor inertia time constant of the doubly fed wind turbine generator set respectively; K m is the rigidity coefficient between the doubly-fed wind turbine generator set and the wind turbine connecting shaft; ω b is the base value of the system electrical angular velocity, ω osc represents the natural low frequency oscillation frequency.

5. The method for suppressing low-frequency oscillation of a doubly-fed wind turbine based on pitch angle control according to claim 4, characterized in that: Obtaining the rotor shaft angular velocity of the wind rotor shaft and the rotor shaft angular velocity of the rotor shaft includes: Collecting a wind wheel shaft speed pulse signal of the wind wheel shaft and a wind wheel shaft speed pulse signal of the rotor shaft; performing filtering processing on the wind wheel shaft speed pulse signal and the rotor shaft speed pulse signal respectively; The wind wheel shaft speed is obtained according to the wind wheel shaft speed pulse signal and the preset number of pulses per revolution, and the rotor shaft speed is obtained according to the rotor shaft speed pulse signal and the preset number of pulses per revolution; The wind wheel shaft angular velocity and the rotor shaft angular velocity are obtained according to the wind wheel shaft rotational speed and the rotor shaft rotational speed.

6. The method for suppressing low-frequency oscillation of a doubly-fed wind turbine based on pitch angle control according to claim 5, characterized in that: The controller transfer function of the additional damping controller is obtained according to the natural low-frequency oscillation frequency of the dual-mass block and the angular velocity difference, including: Obtaining the natural low-frequency oscillation frequency of the dual-mass block; Establishing a transfer function of the damping torque coefficient between the electromagnetic torque increment of the doubly-fed wind turbine generator set and the angular velocity difference; Obtaining a phase characteristic at the natural low-frequency oscillation frequency based on a transfer function expression of the damping torque coefficient, and obtaining a phase compensation phase angle; A controller transfer function of the additional damping controller is obtained according to the phase compensation phase angle.

7. The method for suppressing low-frequency oscillation of a doubly-fed wind turbine based on pitch angle control according to claim 6, characterized in that: The compensating and controlling the rotor speed of the doubly-fed wind turbine generator based on the rotor speed compensation value includes: Obtaining a preset rotor reference angular velocity; Obtaining a speed compensation result according to the rotor speed compensation value, the preset rotor reference angular velocity, and the rotor shaft angular velocity; The speed compensation result is input into the PI controller.

8. A low-frequency oscillation suppression device for a doubly-fed wind turbine based on pitch angle control, characterized in that: include: An acquisition module, configured to acquire the rotor shaft angular velocity of the wind rotor shaft and the rotor shaft angular velocity of the rotor shaft; a calculation module, configured to obtain an angular velocity difference according to the angular velocity of the wind wheel shaft and the angular velocity of the rotor shaft; an analysis module, configured to obtain a controller transfer function of an additional damping controller according to the natural low-frequency oscillation frequency of the dual-mass block, the angular velocity difference, and the electromagnetic torque increment of the doubly-fed wind turbine generator set; an output module, configured to obtain a rotor speed compensation value based on the angular velocity difference and the controller transfer function; The compensation module is used to perform compensation control on the rotor speed of the doubly-fed wind turbine based on the rotor speed compensation value.

9. A low-frequency oscillation suppression device for a doubly-fed wind turbine based on pitch angle control, characterized in that: include: memory for storing computer programs; A processor is configured to implement the steps of the method for suppressing low-frequency oscillation of a doubly-fed wind turbine based on pitch angle control as described in any one of claims 1 to 7 when executing the computer program.

10. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of the method for suppressing low-frequency oscillation of a doubly-fed wind turbine based on pitch angle control according to any one of claims 1 to 7.

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