Optimal position determination method and device for shafting damper controller of network-constructed double-fed wind turbine

Abstract

This invention discloses a method and apparatus for determining the optimal position of the shaft damping controller in a grid-type doubly-fed induction generator (DFIG). A damping controller based on rotational speed signals is added to different control loops. The differences in shaft damping caused by adding the damping controller to different control loops are compared based on the root locus diagram of the DFIG. Results show that implementing the damping controller in the active power loop reduces transmission system damping compared to the voltage loop. Furthermore, applying the damping controller to the q-axis voltage provides a better damping enhancement effect than applying it to the d-axis voltage.

Description

Technical Field

[0001] This application relates to the field of wind power generation control technology, specifically to a method and device for determining the optimal position of a shaft damping controller for a grid-type doubly fed wind turbine. Background Technology

[0002] With the energy crisis and environmental pollution becoming increasingly severe, the installed capacity of global wind power systems continues to grow. Wind power systems based on doubly-fed induction generators have been widely used in practical applications due to their advantages such as small converter capacity, low cost, and flexible power regulation.

[0003] The electrical and mechanical systems of a doubly-fed induction generator (DFIG) wind turbine exhibit electromechanical interactions, necessitating coordinated control between the converter and the turbine's main control system for stable operation. When subjected to external disturbances, this interaction can excite the DFIG's inherent torsional vibration modes, leading to shaft torsional vibration. This vibration generates fatigue loads on transmission system components, increasing maintenance costs and potentially causing shaft breakage and severe damage to the wind turbine generator. Employing grid-based control strategies further amplifies these electromechanical interactions, increasing the risk of shaft torsional vibration.

[0004] Currently, the following research has been conducted both domestically and internationally on the shaft torsional vibration problem of grid-type doubly-fed induction generators (DFIGs): 1) Time-domain simulations show that, compared to grid-type control, grid-type control makes DFIGs more prone to shaft torsional vibration. 2) Modeling indicates that virtual inertia and virtual damping coefficient are key parameters affecting instantaneous torque. 3) When the grid-type control bandwidth is smaller than the torsional vibration frequency of the transmission system, the risk of shaft torsional vibration increases.

[0005] In summary, the above studies only analyzed the torsional vibration characteristics of grid-type doubly-fed wind turbines, without conducting in-depth research on their shaft torsional vibration suppression strategies. Since the power loop bandwidth and voltage loop bandwidth of grid-type wind turbines are similar, the position of adding damping controllers is more flexible compared to grid-type doubly-fed wind turbines. It is urgent to determine the optimal position of the damping controllers in order to effectively improve the shaft damping of wind turbine units. Summary of the Invention

[0006] In view of this, the present invention provides a method and apparatus for determining the optimal position of the shaft damping controller of a grid-type doubly-fed induction generator (DFIG). By adding damping controllers to different control loops, the optimal position of the damping controller is selected, providing a reference for improving the grid connection stability of the DFIG.

[0007] According to a first aspect of the embodiments of this application, a method for determining the optimal position of a shaft damping controller for a grid-type doubly fed wind turbine is provided, comprising:

[0008] A damping controller based on the rotational speed signal is used and is added to the active power loop and voltage loop of the grid-type doubly fed wind turbine, respectively.

[0009] Based on the mechanical parameters of the wind turbine and the motor, the shaft torsional vibration mode of the grid-type doubly fed wind turbine is calculated;

[0010] The characteristic values ​​of the grid-type doubly fed wind turbine are obtained by calculating the characteristic equation, the characteristic values ​​of the shaft torsional vibration mode are extracted, and then the root locus diagram of the characteristic values ​​is plotted by setting different short-circuit ratios.

[0011] Stability analysis of a grid-type doubly fed wind turbine with or without a damping controller on the power loop was performed using root locus plots. The results showed that implementing a damping controller on the active power loop would reduce the damping of the transmission system.

[0012] Stability analysis of a grid-type doubly fed wind turbine with or without a damping controller on the voltage loop was performed using root locus plots. The results showed that implementing a damping controller on the voltage loop would improve the damping of the transmission system.

[0013] Comparative analysis of implementing damping controllers on the d-axis and q-axis of the voltage loop reveals that applying a damping controller on the q-axis achieves the optimal damping enhancement effect.

[0014] According to a second aspect of the embodiments of this application, an optimal position determination device for a grid-type doubly fed wind turbine shaft damping controller is provided, comprising:

[0015] Add a module for using a damping controller based on the speed signal, and add it to the active power loop and voltage loop of the grid-type doubly fed wind turbine respectively;

[0016] The calculation module is used to calculate the shaft torsional vibration mode of the grid-type doubly-fed wind turbine based on the mechanical parameters of the wind turbine and the motor.

[0017] The drawing module is used to obtain the corresponding eigenvalues ​​by calculating the characteristic equation of the grid-type doubly fed wind turbine, extract the eigenvalues ​​corresponding to the shaft torsional vibration mode, and then draw the eigenvalue root locus diagram by setting different short-circuit ratios.

[0018] The first analysis module is used to perform stability analysis on the grid-type doubly fed wind turbine with or without a damping controller on the power loop using the root locus diagram, and to conclude that implementing a damping controller on the active power loop will reduce the damping of the transmission system.

[0019] The second analysis module is used to perform stability analysis on the grid-type doubly fed wind turbine with or without a damping controller on the voltage loop using root locus diagrams, and to conclude that implementing a damping controller on the voltage loop will increase the damping of the transmission system.

[0020] The optimal position determination module is used to compare and analyze the implementation of damping controllers on the d-axis and q-axis of the voltage loop, and finally finds that applying a damping controller on the q-axis can achieve the optimal damping enhancement effect.

[0021] According to a third aspect of the embodiments of this application, an electronic device is provided, comprising:

[0022] One or more processors;

[0023] Memory, used to store one or more programs;

[0024] When the one or more programs are executed by the one or more processors, the one or more processors perform the method as described in the first aspect.

[0025] According to a fourth aspect of the embodiments of this application, a computer-readable storage medium is provided that stores computer instructions thereon, which, when executed by a processor, implement the steps of the method as described in the first aspect.

[0026] The technical solutions provided by the embodiments of this application may include the following beneficial effects:

[0027] A damping controller based on rotational speed signals was applied to both the active power loop and voltage loop of a grid-type doubly-fed induction generator (DFIG). Based on the mechanical parameters of the turbine and motor, the torsional vibration modes corresponding to the natural oscillation frequencies of the DFIG shaft system were calculated. The characteristic equations of the DFIG system under different short-circuit ratios were calculated to obtain the corresponding eigenvalues. The changes in eigenvalues ​​corresponding to the torsional vibration modes were extracted, and root locus plots were drawn. Stability analysis was performed on the DFIG with and without a damping controller applied to the power loop using the root locus plots. Stability analysis was also performed on the DFIG with and without a damping controller applied to the voltage loop using the root locus plots. According to the stability analysis results, implementing a damping controller on the active power loop reduces the damping of the transmission system, while implementing a damping controller on the voltage loop increases the damping of the transmission system. Compared to implementing a damping controller on the d-axis voltage loop, applying it to the q-axis voltage loop yields a better damping enhancement effect. This method can maximize the shaft damping performance of grid-type doubly-fed wind turbines, reduce the negative damping caused by grid-type control, and thus reduce the risk of shaft torsional vibration.

[0028] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0029] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0030] Figure 1This is a flowchart illustrating an optimal position determination method for a grid-type doubly fed wind turbine shaft damping controller according to an exemplary embodiment.

[0031] Figure 2 This is a schematic diagram of grid-connected operation of a doubly fed wind turbine provided in an embodiment of the present invention.

[0032] Figure 3 This is a control block diagram of adding damping controllers at different locations according to an embodiment of the present invention.

[0033] Figure 4 This is the root locus diagram of whether or not method 1 is implemented, as provided in the embodiments of the present invention.

[0034] Figure 5 This is a root locus diagram showing whether or not methods 2 and 3 are implemented, as provided in the embodiments of the present invention.

[0035] Figure 6 The figures show the experimental results of adding damping controllers to different control stages.

[0036] Figure 7 This is a block diagram illustrating an optimal position determination device for a grid-type doubly fed fan shaft damping controller according to an exemplary embodiment.

[0037] Figure 8 This is a block diagram illustrating an electronic device according to an exemplary embodiment. Detailed Implementation

[0038] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0039] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The singular forms “a,” “the,” and “the” used in this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0040] Figure 1 This is a flowchart illustrating an optimal position determination method for a grid-type doubly-fed wind turbine shaft damping controller according to an exemplary embodiment, such as... Figure 1 As shown, the method may include the following steps:

[0041] S1: A damping controller based on the speed signal is used and added to the active power loop and voltage loop of the grid-type doubly fed wind turbine respectively;

[0042] Specifically, the active power loop bandwidth and voltage loop bandwidth of a grid-type doubly-fed induction generator (DFIG) are close. Therefore, compared with a grid-type dual-control generator, the selection of its damping controller is more flexible. It can be placed not only on the active power loop but also added to the voltage loop, thus providing more control dimensions for the coordinated damping control of multiple generators. A specific block diagram is shown below. Figure 2 and Figure 3 As shown;

[0043] Damping controller: ;

[0044] in, G d Indicates a damping controller; K d This indicates the gain of the damping controller; s Represents the Laplace operator; T ω This represents the time constant of the DC blocking element.

[0045] S2: Calculate the shaft torsional vibration mode of the grid-type doubly-fed wind turbine based on the mechanical parameters of the wind turbine and the motor;

[0046] Specifically, the shaft torsional vibration modes of the grid-type doubly-fed wind turbine are calculated using the following formula:

[0047] ;

[0048] in, f osc For shaft system torsional vibration modes; π Pi; K m This is the mechanical stiffness coefficient; H t , H g These are the equivalent inertia of the wind turbine and the equivalent inertia of the electric motor, respectively. ω 1 represents the power frequency angular frequency.

[0049] S3: Obtain the corresponding eigenvalues ​​by calculating the characteristic equation of the grid-type doubly fed wind turbine, extract the eigenvalues ​​corresponding to the shaft torsional vibration mode, and then draw the eigenvalue root locus diagram by setting different short-circuit ratios;

[0050] Specifically, by calculating the characteristic values ​​of a grid-type doubly-fed wind turbine, the variation law of the shaft system torsional vibration modes is analyzed. Compared with the single-input limitation of the Bode plot method and the experimental dependence of time-domain simulation, the eigenvalue analysis method can directly obtain the accurate frequency and damping ratio of all oscillation modes of the system. The specific characteristic equations are as follows:

[0051] ;

[0052] in, λ For eigenvalues; D For virtual damping; J This is virtual inertia; ω b It is the power frequency angular frequency; G ( s To consider the combined effect of the short-circuit ratio on the eigenvalue under the damping controller.

[0053] Then, the short-circuit ratio is changed to change the characteristic equation, and the corresponding eigenvalue is calculated to obtain the change of the real part of the eigenvalue under the torsional vibration mode. By setting different short-circuit ratios, the eigenvalue root locus diagram is plotted to intuitively show the change law of the shaft system torsional vibration mode. When the real part is less than 0, it indicates that the shaft system damping is positive; when the real part is greater than 0, it indicates that the shaft system damping is negative.

[0054] S4: Stability analysis of the grid-type doubly fed wind turbine with and without a damping controller on the power loop was performed using the root locus diagram. It was found that implementing a damping controller on the active power loop would reduce the damping of the transmission system.

[0055] Specifically, to further analyze the impact of adding a damping controller to the power loop, Figure 4 This is the root locus diagram for whether or not Method 1 (adding a damping controller to the power loop) was implemented. After implementing Method 1, the shaft damping was further reduced. The reason for this phenomenon is that the shaft torsional vibration of the grid-type doubly-fed wind turbine is due to the effect of the power loop. Adding a damping controller to the active power command does not reduce the phase difference between the electromagnetic torque and the rotor speed; instead, it amplifies the oscillation amplitude of the rotor speed.

[0056] S5: Stability analysis of a grid-type doubly fed wind turbine with or without a damping controller on the voltage loop was performed using root locus plots. The results showed that implementing a damping controller on the voltage loop would increase the damping of the transmission system.

[0057] Specifically, Figure 5 This is the root locus plot showing whether or not methods 2 and 3 (adding a damping controller to the voltage loop) are implemented. Both methods 2 and 3 effectively enhance the damping of the transmission system.

[0058] S6: Comparative analysis shows that applying a damping controller on the d-axis and q-axis of the voltage loop ultimately achieves the optimal damping enhancement effect by applying a damping controller on the q-axis.

[0059] Specifically, comparative analysis shows that applying the damping controller to method 3 (q-axis voltage loop) results in a better damping effect than method 2 (d-axis voltage loop). Based on this, the present invention adds a damping controller to the q-axis voltage loop.

[0060] The above analysis results were verified through hardware-in-the-loop experiments:

[0061] Hardware-in-the-loop experiments were conducted using the Typhoon 602+ experimental platform. A grid-connected converter system was constructed within the Typhoon 602+, and the system's control circuitry was implemented using an actual TMS320F28335 / Spartan 6 XC6SLX16 DSP+FPGA hardware circuit board. This application then compared the differences between three damping controllers, such as... Figure 6 As shown. Figure 6 The graph shows the experimental results of adding damping controllers to different control stages, based on... Figure 6 As shown in (a), the implementation of method 1 not only failed to alleviate the shaft torsional vibration of the grid-type doubly-fed wind turbine, but also further worsened the shaft damping. Conversely, Figure 6 Figures (b) and (c) show that both Method 2 and Method 3 effectively suppress shaft torsional vibration when the damping controller is enabled. After using Method 2 and Method 3, the total harmonic distortion (THD) of the rotor speed decreased from 15.97% to 0.67% and 0.43%, respectively. Furthermore, Method 3 provides significantly less suppression time for torsional vibration than Method 2. Therefore, Method 3 provides greater damping for the transmission system compared to Method 2. These phenomena confirm and validate the effectiveness of the proposed control strategy.

[0062] Figure 7 This is a block diagram illustrating an optimal position determination device for a grid-type doubly-fed wind turbine shaft damping controller according to an exemplary embodiment. The device may include:

[0063] Add module 1, which is used to employ a damping controller based on the speed signal, and add it to the active power loop and voltage loop of the grid-type doubly fed wind turbine respectively;

[0064] Calculation module 2 is used to calculate the shaft torsional vibration mode of the grid-type doubly-fed wind turbine based on the mechanical parameters of the wind turbine and the motor.

[0065] The drawing module 3 is used to obtain the corresponding eigenvalues ​​by calculating the characteristic equation of the grid-type doubly fed wind turbine, extract the eigenvalues ​​corresponding to the shaft torsional vibration mode, and then draw the eigenvalue root locus diagram by setting different short-circuit ratios.

[0066] The first analysis module 4 is used to perform stability analysis on the grid-type doubly fed wind turbine with or without a damping controller on the power loop using the root locus diagram, and to conclude that implementing a damping controller on the active power loop will reduce the damping of the transmission system.

[0067] The second analysis module 5 is used to perform stability analysis on the grid-type doubly fed wind turbine with or without a damping controller on the voltage loop using the root locus diagram, and to conclude that implementing a damping controller on the voltage loop will increase the damping of the transmission system.

[0068] The optimal position determination module 6 is used to compare and analyze the implementation of damping controllers on the d-axis and q-axis of the voltage loop, and finally finds that applying a damping controller on the q-axis can achieve the optimal damping enhancement effect.

[0069] Regarding the apparatus in the above embodiments, the specific manner in which each module performs its operation has been described in detail in the embodiments related to the method, and will not be elaborated upon here.

[0070] For the device embodiments, since they basically correspond to the method embodiments, the relevant parts can be referred to in the description of the method embodiments. The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this application according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0071] Accordingly, this application also provides an electronic device, including: one or more processors; a memory for storing one or more programs; when the one or more programs are executed by the one or more processors, the one or more processors implement the above-described method for determining the optimal position of a grid-type doubly-fed wind turbine shaft damping controller. Figure 8 The diagram shown is a hardware structure diagram of any device with data processing capabilities, which is used to determine the optimal position of a grid-type doubly fed wind turbine shaft damping controller according to an embodiment of the present invention. (Except for...) Figure 8 In addition to the processor and memory shown, any data processing device in the embodiment may also include other hardware depending on the actual function of the data processing device, which will not be described in detail here.

[0072] Accordingly, this application also provides a computer-readable storage medium storing computer instructions, which, when executed by a processor, implement the optimal position determination method for the shaft damping controller of a grid-type doubly-fed wind turbine as described above. The computer-readable storage medium can be an internal storage unit of any data-processing device as described in any of the foregoing embodiments, such as a hard disk or memory. The computer-readable storage medium can also be an external storage device, such as a plug-in hard disk, smart media card (SMC), SD card, flash card, etc., equipped on the device. Furthermore, the computer-readable storage medium can include both internal storage units of any data-processing device and external storage devices. The computer-readable storage medium is used to store the computer program and other programs and data required by the data-processing device, and can also be used to temporarily store data that has been output or will be output.

[0073] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and embodiments are to be considered exemplary only, and the true scope and spirit of this application are indicated by the claims.

[0074] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A method for determining the optimal position of a shaft damping controller for a grid-type doubly-fed wind turbine, characterized in that, include: A damping controller based on the rotational speed signal is used and is added to the active power loop and voltage loop of the grid-type doubly fed wind turbine, respectively. Based on the mechanical parameters of the wind turbine and the motor, the shaft torsional vibration mode of the grid-type doubly fed wind turbine is calculated; The characteristic values ​​of the grid-type doubly fed wind turbine are obtained by calculating the characteristic equation, the characteristic values ​​of the shaft torsional vibration mode are extracted, and then the root locus diagram of the characteristic values ​​is plotted by setting different short-circuit ratios. Stability analysis of a grid-type doubly fed wind turbine with or without a damping controller on the power loop was performed using root locus plots. The results showed that implementing a damping controller on the active power loop would reduce the damping of the transmission system. Stability analysis of a grid-type doubly fed wind turbine with or without a damping controller on the voltage loop was performed using root locus plots. The results showed that implementing a damping controller on the voltage loop would improve the damping of the transmission system. Comparative analysis of implementing damping controllers on the d-axis and q-axis of the voltage loop reveals that applying a damping controller on the q-axis achieves the optimal damping enhancement effect.

2. The method according to claim 1, characterized in that, The damping controller based on the rotational speed signal is as follows: ； in, G d Indicates a damping controller; K d This indicates the gain of the damping controller; s Represents the Laplace operator; T ω This represents the time constant of the DC blocking element.

3. The method according to claim 1, characterized in that, The shaft torsional vibration modes of the grid-type doubly-fed wind turbine are calculated using the following formula: ； in, f osc For shaft system torsional vibration modes; π Pi; K m This is the mechanical stiffness coefficient; H t , H g These are the equivalent wind turbine inertia and the equivalent motor inertia, respectively. ω 1 represents the power frequency angular frequency.

4. The method according to claim 1, characterized in that, The characteristic equation is as follows: ； in, λ For eigenvalues; D For virtual damping; J This is virtual inertia; ω b It is the power frequency angular frequency; G ( s To consider the combined effect of the short-circuit ratio on the eigenvalue under the damping controller.

5. A device for determining the optimal position of a shaft damping controller for a grid-type doubly fed wind turbine, characterized in that, include: Add a module for using a damping controller based on the speed signal, and add it to the active power loop and voltage loop of the grid-type doubly fed wind turbine respectively; The calculation module is used to calculate the shaft torsional vibration mode of the grid-type doubly-fed wind turbine based on the mechanical parameters of the wind turbine and the motor. The drawing module is used to obtain the corresponding eigenvalues ​​by calculating the characteristic equation of the grid-type doubly fed wind turbine, extract the eigenvalues ​​corresponding to the shaft torsional vibration mode, and then draw the eigenvalue root locus diagram by setting different short-circuit ratios. The first analysis module is used to perform stability analysis on the grid-type doubly fed wind turbine with or without a damping controller on the power loop using the root locus diagram, and to conclude that implementing a damping controller on the active power loop will reduce the damping of the transmission system. The second analysis module is used to perform stability analysis on the grid-type doubly fed wind turbine with or without a damping controller on the voltage loop using root locus diagrams, and to conclude that implementing a damping controller on the voltage loop will increase the damping of the transmission system. The optimal position determination module is used to compare and analyze the implementation of damping controllers on the d-axis and q-axis of the voltage loop, and finally finds that applying a damping controller on the q-axis can achieve the optimal damping enhancement effect.

6. An electronic device, characterized in that, include: One or more processors; Memory, used to store one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors implement the method as described in any one of claims 1-4.

7. A computer-readable storage medium storing computer instructions thereon, characterized in that, When executed by the processor, this instruction implements the steps of the method as described in any one of claims 1-4.

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