Double-fed fan frequency change suppression method, system, equipment and medium

Abstract

The invention discloses a doubly-fed fan frequency change suppression method, system and device and a medium, and belongs to the technical field of doubly-fed fan control, and the method comprises the steps: collecting the detection data of a power grid where a doubly-fed fan is located, and calculating the phase locking frequency according to the detection data; calculating the frequency change rate of the power grid according to the phase locking frequency and the transfer function; according to the frequency change rate, a control signal is calculated and obtained through a reactive df / dt control algorithm; adding the control signal to a current instruction of the doubly-fed fan, and adjusting an internal potential component of the doubly-fed fan; adjusting the power angle difference between the internal potential of the doubly-fed fan and the power grid terminal voltage according to the internal potential component, and controlling the power grid frequency; and the output of the signal is controlled by judging the change trend of the power grid frequency. According to the invention, the problem that the recovery speed of the doubly-fed fan is slowed down or the safe operation of equipment and a system is affected by the existing df / dt control is solved.

Description

Technical Field

[0001] This invention relates to the field of doubly fed fan control technology, specifically to a method, system, device, and medium for suppressing frequency variations in doubly fed fans. Background Technology

[0002] Wind power generation is a technology that uses wind energy to drive the rotation of wind turbine blades, which is then converted into electrical energy by a generator. It is a renewable energy technology characterized by its environmental friendliness and sustainability. Doubly-fed induction generator (DFIG) wind power generation technology is an important branch of wind power generation, utilizing frequency conversion technology to achieve an efficient combination of wind energy conversion and grid connection. DFIG wind power generation technology not only improves the efficiency of wind power generation but also provides a new solution for the stable operation of the power grid.

[0003] Doubly-fed induction generator (DFIG) technology is the core of modern wind energy utilization. Through a unique DFIG design, it achieves constant voltage and frequency output to the grid under fluctuating wind speeds. This technology includes two operation phases: grid-connected and off-grid, and employs torque, power, and voltage control strategies. A complex control system ensures the efficient and stable operation of the wind turbine generator set.

[0004] In traditional power systems with synchronous mechanisms, the system frequency is determined only by active power. However, the electromotive force frequency of a doubly-fed induction generator (DFIG) is determined by both active and reactive power. This characteristic provides a theoretical possibility for using the reactive power capacity of the turbine to suppress the system frequency. Summary of the Invention

[0005] In view of the above-mentioned problems, the present invention is proposed.

[0006] Therefore, the technical problem solved by this invention is: how to suppress the frequency change of a doubly fed fan by means of a frequency change suppression method, thereby enhancing the instantaneous active power support capability of the fan and improving its ability to suppress system frequency changes.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for suppressing frequency variation of a doubly-fed induction generator (DFIG) wind turbine, comprising the following steps: collecting detection data of the power grid where the DFIG wind turbine is located; calculating the phase-locked frequency based on the detection data; calculating the frequency variation rate of the power grid based on the phase-locked frequency and a transfer function; calculating and obtaining a control signal based on the frequency variation rate using a reactive power df / dt control algorithm; adding the control signal to the current command of the DFIG wind turbine to adjust the internal potential component of the DFIG wind turbine; adjusting the power angle difference between the internal potential of the DFIG wind turbine and the grid terminal voltage based on the internal potential component to control the grid frequency; and controlling the output of the control signal by judging the trend of grid frequency variation.

[0008] As a preferred embodiment of the frequency variation suppression method for a doubly fed wind turbine according to the present invention, the step of obtaining the phase-locked frequency includes: extracting the terminal voltage of the doubly fed wind turbine from the detection data; transforming the terminal voltage to obtain the q-axis component of the transformed terminal voltage; and calculating the phase-locked frequency by inputting the q-axis component into the phase-locked frequency calculation formula.

[0009] In a preferred embodiment of the doubly-fed induction generator (DFIG) frequency variation suppression method of the present invention, the step of obtaining the frequency variation rate includes: extracting the variation characteristics of the phase-locked frequency through the transfer function to obtain the initial frequency variation rate; and filtering the initial frequency variation rate to obtain the final frequency variation rate. The beneficial effects of this preferred embodiment are that by extracting the phase-locked frequency variation characteristics through the transfer function of the reactive power DF / DT controller, data support is provided for subsequent control signal calculation. During the processing of the initial frequency variation rate, filtering is performed to remove high-frequency noise in digital control, reducing command fluctuations. Based on the frequency variation rate and the control signal generated by the reactive power DF / DT control algorithm, the suppression effect on system frequency variation is enhanced.

[0010] In a preferred embodiment of the frequency variation suppression method for a doubly-fed induction generator (DFIG) described in this invention, the step of acquiring the control signal includes: acquiring an initial control signal by inputting the frequency variation rate into the transfer function of the reactive power df / dt control algorithm according to a preset proportional parameter and time constant; and acquiring the control signal by performing a difference operation between the initial control signal and the per-unit value of the rated power. The beneficial effects of this preferred embodiment are that it can quickly respond to disturbances while filtering out high-frequency noise by extracting frequency dynamic characteristics through the transfer function, ensuring the stability of the initial signal; achieving signal unification through the difference operation, facilitating the superposition of current commands; and using the final control signal to consolidate and adjust the internal potential and power angle difference of the DFIG, thereby enhancing the frequency variation suppression capability.

[0011] As a preferred embodiment of the frequency variation suppression method for a doubly-fed induction generator (DFIG) according to the present invention, the step of adjusting the internal potential component of the DFIG includes: the DFIG applying the control signal to the current command to adjust the current command of the q-axis; changing the d-axis component of the DFIG by controlling the change of the current command; when the rated active power is insufficient, the internal potential component decreases by a factor of X; when the rated active power is excessive, the internal potential component increases by a factor of Y. The beneficial effects of this preferred embodiment are that by associating the control signal with the current command, the control signal is applied to the rotor q-axis current command, directly adjusting the change of the current command to change the d-axis component of the DFIG internal potential, ensuring rapid response control of the internal potential component; different adjustment methods are implemented for different operating conditions, and the internal potential component is adjusted according to the rated active power, which can improve active power output or avoid excessive frequency rise; adjustment is made according to the reactive power control branch, avoiding the damping reduction, oscillation, and shaft torsional vibration problems caused by the additional control command in traditional df / dt control.

[0012] In a preferred embodiment of the frequency variation suppression method for a doubly-fed induction generator (DFIG) according to the present invention, the power angle difference constraint between the DFIG internal potential and the grid terminal voltage is adjusted according to the change in internal potential; when the internal potential component decreases by a factor of X, the power angle difference constraint is reduced to a factor of N; when the internal potential component increases by a factor of Y, the power angle difference constraint is expanded to a factor of M; and the grid frequency is controlled according to the adjusted power angle difference constraint.

[0013] As a preferred embodiment of the doubly fed wind turbine frequency variation suppression method of the present invention, the judgment step of the control signal output includes: when the frequency variation trend of the grid frequency changes from decreasing to increasing, or when the frequency variation trend of the grid frequency changes from increasing to decreasing, the output of the control signal is terminated; otherwise, the output of the control signal is maintained until the grid frequency changes from decreasing to increasing or from increasing to decreasing.

[0014] This invention provides a frequency variation suppression system for doubly fed wind turbines.

[0015] To solve the above-mentioned technical problems, the present invention further provides the following technical solution: a doubly-fed induction generator (DFIG) frequency variation suppression system, comprising: a phase-locked frequency calculation module, which collects detection data of the power grid where the DFIG is located and calculates the phase-locked frequency based on the detection data; a frequency variation rate calculation module, which calculates the frequency variation rate of the power grid based on the phase-locked frequency and a transfer function; a control signal calculation module, which calculates and obtains a control signal based on the frequency variation rate using a reactive power df / dt control algorithm; an internal potential component adjustment module, which adds the control signal to the current command of the DFIG to adjust the internal potential component of the DFIG; adjusts the power angle difference between the internal potential of the DFIG and the grid terminal voltage based on the internal potential component to control the grid frequency; and a control signal control module, which controls the output of the control signal by judging the trend of the grid frequency variation.

[0016] The present invention provides a computer device, including a memory and a processor, wherein the memory stores a computer program, characterized in that the processor executes the computer program to implement the steps of the doubly fed wind turbine frequency variation suppression method.

[0017] The present invention provides a computer-readable storage medium having a computer program stored thereon, characterized in that the computer program, when executed by a processor, implements the steps of the doubly fed wind turbine frequency variation suppression method.

[0018] The beneficial effects of this invention are as follows: By adding df / dt control to the doubly-fed induction generator (DFIG) wind turbine, this invention utilizes the relationship between the reactive power of the DFIG and the frequency of its internal potential to ensure that when the system is short of active power, the d-axis component of the internal potential is reduced, thereby increasing the power angle difference between the internal potential and the terminal voltage, rapidly increasing the active power output, suppressing the system frequency drop, and avoiding excessive frequency fluctuations that could affect grid stability. By collecting stator current, output current, and terminal voltage data to support vector control and phase-locked loop operation, and combining preset proportional parameters and time constants to construct a transfer function, a control signal is generated. According to different operating conditions, the internal potential component is adjusted to improve the frequency regulation adaptability after wind power grid connection. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 The above is a flowchart of a method for suppressing frequency variation in a doubly fed wind turbine, provided as an embodiment of the present invention. Detailed Implementation

[0021] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0022] Example 1, referring to Figure 1 This is the first embodiment of the present invention, which provides a method for suppressing frequency variations in a doubly-fed induction generator (DFIG) wind turbine, comprising: S100: Collects detection data from the power grid where the doubly fed wind turbine is located, and calculates the phase-locked frequency based on the detection data.

[0023] S200: Calculate the frequency change rate of the power grid based on the phase-locked loop frequency and the transfer function.

[0024] S300: Based on the frequency change rate, the control signal is calculated and obtained through the reactive power df / dt control algorithm.

[0025] S400: Adds a control signal to the current command of the doubly-fed fan to adjust the internal potential component of the doubly-fed fan.

[0026] S500: Adjusts the power angle difference between the internal potential of the doubly fed fan and the grid terminal voltage according to the internal potential component, and controls the grid frequency.

[0027] S600: Controls the output of signals by judging the changing trend of the power grid frequency.

[0028] It should be noted that existing df / dt control uses a differential relationship, which slows down the frequency recovery speed in the doubly-fed induction generator (DFIG) when the damping coefficient is small, and adversely affects the safe operation of the equipment and system when the damping coefficient is large. Therefore, adding df / dt control to the electromagnetic torque command value of the DFIG has certain shortcomings in suppressing frequency changes. In traditional power systems, the system frequency is determined solely by active power, while the electromotive force inside the DFIG is processed by combining active and reactive power to control the system frequency. This characteristic provides a theoretical basis for using the reactive power capacity of the turbine to suppress the system frequency.

[0029] Therefore, to address the issue that existing df / dt control methods can slow down the recovery speed of doubly-fed induction generators (DFIGs) or adversely affect the safe operation of equipment and systems, a frequency variation suppression method for DFIGs is constructed through steps S100-S600. First, detection data from the power grid where the DFIG is located is collected. The phase-locked frequency (PLF) is calculated based on the detection data, and the frequency variation rate of the power grid is calculated using the transfer function based on the PLF. Second, based on the frequency variation rate, a control signal is calculated using a reactive power df / dt control algorithm and added to the current command of the DFIG to adjust the internal potential component of the DFIG. Then, the power angle difference between the internal potential of the DFIG and the grid terminal voltage is adjusted based on the internal potential component to control the grid frequency. Finally, the output of the control signal is determined by judging the trend of the grid frequency variation.

[0030] Example 2, refer to Figure 1 This is the second embodiment of the present invention, which provides a method for suppressing frequency changes in a doubly fed fan.

[0031] In this embodiment of the invention, step S100 involves collecting detection data from the power grid where the doubly-fed wind turbine is located and calculating the phase-locked frequency based on the detection data, including the following steps A1~A2: A1: Collect detection data from the power grid where the doubly fed wind turbine is located.

[0032] Specifically, the detection data collected from the power grid where the doubly fed induction generator (DFIG) is located includes the stator current, output current, and terminal voltage of the DFIG. These data serve as the data support for the DFIG's vector control, phase-locked loop (PLL), and df / dt control.

[0033] A2: Obtain the phase-locked frequency.

[0034] Specifically, obtaining the phase-locked frequency includes the following steps A21~A22: A21: Transform the terminal voltage to obtain the q-axis component of the transformed terminal voltage.

[0035] Specifically, a Park transformation is performed on the acquired doubly-fed induction generator (DFIG) terminal voltage, converting it from a three-phase stationary coordinate system to a rotating coordinate system with the phase-locked loop (PLL) output phase as the reference angle. This yields the transformed q-axis component of the terminal voltage, denoted as... .

[0036] In one possible implementation, the Park transform can also be replaced by the Clark transform combined with a coordinate rotation algorithm. The Clark transform first converts the terminal voltage of the three-phase stationary coordinate system into two-phase stationary αβ coordinate system components, and then calculates the rotation matrix based on the phase-locked loop output phase to rotate the αβ components, thereby obtaining the q-axis component of the rotating coordinate system with the phase-locked loop phase as the reference.

[0037] In another possible implementation, the Park transform can be replaced by a direct phase compensation algorithm based on the phase-locked loop phase. By using the phase output phase of the phase-locked loop to perform phase compensation on the three-phase terminal voltage, the intermediate coordinate system transformation can be skipped directly, and the q-axis component in the rotating coordinate system can be extracted directly.

[0038] A22: The phase-locked frequency is calculated by inputting the q-axis component into the phase-locked frequency calculation formula.

[0039] Specifically, the specific form of calculating the phase-locked frequency is as follows: ; In the formula, This represents the output frequency of the phase-locked loop (PLL). The q-axis component of the representative terminal voltage is obtained after Park transformation. The proportional parameter of the PI element in the phase-locked loop; These are the integral parameters of the phase-locked loop PI circuit.

[0040] In this embodiment of the invention, step S200, which calculates the frequency change rate of the power grid based on the phase-locked loop frequency and the transfer function, includes the following steps B1~B2: B1: Extract the change characteristics of the phase-locked frequency by using the transfer function to obtain the initial frequency change rate.

[0041] Specifically, the phase-locked frequency obtained in step A22 Input into the preset transfer function; The transfer function is specifically represented as follows: ; In the formula, Represent the complex variables of the Laplace transform; The transfer function of the reactive power df / dt controller is represented by K, which is equivalent to a cascaded differential element and a low-pass filter element. K represents the proportional parameter of the controller, and T represents the time constant of the controller.

[0042] B2: Filter the initial frequency change rate to obtain the frequency change rate.

[0043] Specifically, by filtering the initial frequency change rate, high-frequency noise introduced by the differential operation is removed from the initial frequency change rate.

[0044] It should be noted that high-frequency interference is easily amplified in differential operations, causing fluctuations in the initial frequency change rate. Low-pass filtering can make the frequency change rate more stable, ensuring the accuracy of subsequent control signal calculations.

[0045] In one possible implementation, the frequency change rate can be obtained by extracting and filtering the transfer function using a Kalman filter algorithm. The phase-locked frequency is used as the input observation value to the model. Based on the frequency change rate at historical moments, the predicted values ​​of the current frequency and change rate are calculated. The predicted values ​​are then adjusted by combining the observed values ​​with the observation noise model to obtain the frequency change rate. This process extracts the phase-locked frequency change characteristics while also suppressing the high-frequency noise introduced by the differential operation.

[0046] In another possible implementation, the frequency change rate can be obtained by extracting and filtering the transfer function using a moving average filter and a first-order RC low-pass filter circuit. By applying a moving average filter to the phase-locked frequency in a time series, the average value of 5 to 10 phase-locked frequency values ​​is calculated. The initial frequency change rate is then extracted by the frequency difference between adjacent time points. The initial frequency change rate is then input into the first-order RC low-pass filter circuit. Utilizing the current-limiting characteristics of the resistor and the charging and discharging characteristics of the capacitor, the high-frequency interference signal is input to the attenuation differential operation, and finally, a stable frequency change rate is output.

[0047] In this embodiment of the invention, step S300, which calculates and obtains the control signal based on the frequency change rate using a reactive power df / dt control algorithm, includes the following steps C1~C2: C1: Based on the preset proportional parameters and time constant, the initial control signal is obtained by inputting the frequency change rate into the transfer function of the reactive power df / dt control algorithm.

[0048] Specifically, the transfer function used in step C1 is in the same form as the transfer function in step B1. By setting the proportional parameter K and the time constant T, the transfer function of the reactive power df / dt control algorithm is called.

[0049] Furthermore, the frequency change rate obtained in step B2 is used as the input quantity and substituted into the transfer function of the reactive power df / dt control algorithm to obtain the initial control signal.

[0050] It should be noted that the reactive power df / dt control algorithm includes the transfer function, phase-locked loop rate calculation, current command adjustment formula, and grid frequency formula.

[0051] C2: Calculate the difference between the initial control signal and the per-unit value of the rated power to obtain the control signal.

[0052] It should be noted that the initial control signal is converted from a power-related physical quantity into a per-unit control quantity that conforms to the doubly fed wind turbine rotor current command system by performing a difference operation with the per-unit value of the rated power. Since the rotor q-axis current command output by the upstream reactive power and terminal voltage control is expressed in per-unit form, the control signal after the difference operation can be directly superimposed on it.

[0053] In one possible implementation, the control signal can also be obtained through proportional conversion. By utilizing the per-unit value reference relationship between the rated power, rated voltage and rated current of the doubly fed fan, the initial control signal can be directly converted into the per-unit value of the current, and the intermediate concentration signal can be obtained without the need for reverse difference calculation.

[0054] In another possible implementation, the control signal can also be obtained by combining the initial control signal with the deviation calibration method of the feedback of the preceding q-axis current command. The initial intermediate control signal is calibrated by the actual feedback deviation of the preceding rotor q-axis current command, so as to convert it into an appropriate per-unit control signal.

[0055] In this embodiment of the invention, step S400, which involves adding a control signal to the current command of the doubly-fed induction generator (DFIG) to adjust the internal potential component of the DFIG, includes the following steps D1~D2: D1: The doubly fed fan uses the control signal to adjust the current command of the q-axis.

[0056] Specifically, the reactive power df / dt control algorithm applies the control signal to the current command of the doubly-fed induction generator (DFIG) to adjust the current command on the q-axis, as follows: ; In the formula, This represents the rotor q-axis current command value output by the reactive power and terminal voltage control of the preceding stage. This indicates the output frequency of the phase-locked loop; The per-unit value representing the rated frequency is usually taken as 1; Represents the transfer function of the reactive power df / dt controller; This indicates the rotor q-axis current command value after the addition of additional control.

[0057] In one possible implementation, the current adjustment command can also be adjusted by introducing a frequency change rate weighted correction. By superimposing a correction term consisting of the frequency change rate on the original current command adjustment formula, the correction term is set according to the frequency disturbance set based on the controller parameters, ensuring a more accurate control requirement that better matches the frequency dynamic characteristics.

[0058] In another possible implementation, the adjustment current command can also be adjusted by introducing a feedback correction term for the internal potential d-axis component to adjust the rotor q-axis current command. By analyzing the quantitative correlation between the potential d-axis component and the rotor q-axis current, a feedback correction term based on the internal potential d-axis component is added to the original command adjustment formula. The feedback correction term is set by the deviation between the rated internal potential d-axis component and the current internal potential d-axis component.

[0059] D2: By controlling the change of the current command, the d-axis component of the doubly fed fan is changed.

[0060] It should be noted that since the structure of the reactive power df / dt controller is the same as that of the conventional df / dt virtual inertia control, and the inputs are all phase-locked frequencies, the output has the meaning of active power. Taking the system experiencing a shortfall in active power as an example, the generator responds to the active power disturbance, causing the frequency to drop, and the reactive power df / dt controller outputs a positive power command. Since the internal electromotive force dq component of the doubly-fed induction generator is positive, the rotor current q-axis component Irq is negative. The additional command makes the absolute value of the actual command value of Irq smaller than the absolute value of the command value output by the upstream controller, thus playing a role in instantaneously reducing Edp, thereby increasing the power angle between the internal electromotive force and the terminal voltage, enabling the doubly-fed induction generator to output more active power and reducing the change in system frequency.

[0061] In this embodiment of the invention, in step S500, the power angle difference between the internal potential of the doubly fed wind turbine and the grid terminal voltage is adjusted according to the internal potential component to control the grid frequency.

[0062] Specifically, the control of power grid frequency manifests itself in the following ways: ; ; In the formula, This represents the phase-locked loop coordinate system, which is the coordinate system in which the output of each control element that uses the phase-locked loop output phase as a reference angle is located; , Represents the d-axis and q-axis components of the internal electromotive force of a doubly-fed wind turbine; This represents the output frequency of the phase-locked loop (PLL). This physical quantity is the phase-locked frequency. The integral; This indicates the frequency of the internal potential.

[0063] Specifically, the power angle difference constraint between the internal potential of the doubly-fed induction generator (DFIG) and the grid terminal voltage is adjusted according to the change in internal potential. When the internal potential component decreases by 0.7 to 0.9 times, the power angle difference constraint is reduced to 0.6 to 0.8 times. When the internal potential component increases by 1.1 to 1.3 times, the power angle difference constraint is expanded to 1.2 to 1.4 times. The grid frequency is controlled according to the adjusted power angle difference constraint.

[0064] In this embodiment of the invention, step S600 involves judging the changing trend of the power grid frequency and then controlling the output of the signal.

[0065] It should be noted that the judgment is made by observing the trend of the power grid frequency. When the trend of the power grid frequency changes, for example, from a frequency decreasing state to a frequency increasing state or from a frequency increasing state to a frequency decreasing state, it indicates that the trend has reached a minimum or maximum point. At this time, it is necessary to output this frequency change, that is, to output a control signal. If no such frequency change occurs, it means that the current state does not need to be controlled and can be maintained until the trend changes.

[0066] Specifically, the output of the control signal ends when the frequency change trend of the power grid changes from decreasing to increasing, or when the frequency change trend of the power grid changes from increasing to decreasing. Furthermore, if the frequency change trend does not change, the control signal output will continue until the grid frequency changes from decreasing to increasing or from increasing to decreasing.

[0067] In summary, this invention, by adding df / dt control to the doubly-fed induction generator (DFIG), utilizes the relationship between the reactive power of the DFIG and the frequency of its internal potential to ensure that the d-axis component of the internal potential decreases when the system is short of active power. This increases the power angle difference between the internal potential and the terminal voltage, rapidly improving active power output, suppressing system frequency drop, and preventing excessive frequency fluctuations from affecting grid stability. By collecting stator current, output current, and terminal voltage data to support vector control and phase-locked loop operation, and combining preset proportional parameters and time constants to construct a transfer function, a control signal is generated. According to different operating conditions, the internal potential component is adjusted to improve the frequency regulation adaptability after wind power grid connection.

[0068] Example 3 is the third embodiment of the present invention. This embodiment provides a doubly fed fan frequency variation suppression system, including...

[0069] The phase-locked frequency calculation module collects detection data from the power grid where the doubly-fed wind turbine is located and calculates the phase-locked frequency based on the detection data. The frequency change rate calculation module calculates the frequency change rate of the power grid based on the phase-locked frequency and the transfer function. The control signal calculation module calculates and obtains the control signal based on the frequency change rate using the reactive power df / dt control algorithm. The internal potential component adjustment module adds the control signal to the current command of the doubly-fed fan to adjust the internal potential component of the doubly-fed fan. The power angle difference between the internal potential of the doubly-fed wind turbine and the voltage at the grid terminal is adjusted according to the internal potential component to control the grid frequency. The control signal control module determines the output of control signals by judging the changing trend of the power grid frequency.

[0070] Example 4, the fourth embodiment of the present invention, differs from the previous three embodiments in that: if the function is implemented as 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 invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0071] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-including system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device.

[0072] More specific examples of computer-readable media (a non-exhaustive list) include: electrical connections (electronic devices) having one or more wires, portable computer disk drives (magnetic devices), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Furthermore, computer-readable media can even be paper or other suitable media on which the program can be printed, because the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in computer memory.

[0073] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination of all three. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0074] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for suppressing frequency variation in a doubly-fed induction generator (DFIG), characterized in that: include, Collect detection data from the power grid where the doubly fed wind turbine is located, and calculate the phase-locked frequency based on the detection data; The frequency change rate of the power grid is calculated based on the phase-locked frequency and the transfer function. Based on the frequency change rate, the control signal is calculated and obtained using the reactive power df / dt control algorithm; The control signal is added to the current command of the doubly fed fan to adjust the internal potential component of the doubly fed fan. Adjust the power angle difference between the internal potential of the doubly-fed wind turbine and the grid terminal voltage according to the internal potential component, and control the grid frequency; The output of the control signal is controlled by judging the changing trend of the power grid frequency.

2. The method for suppressing frequency variation in a doubly-fed wind turbine as described in claim 1, characterized in that: The steps for obtaining the phase-locked frequency include: Extract the terminal voltage of the doubly fed wind turbine from the detection data; The terminal voltage is transformed to obtain the q-axis component of the transformed terminal voltage; The phase-locked frequency is calculated by inputting the q-axis component into the phase-locked frequency calculation formula.

3. The method for suppressing frequency variation in a doubly-fed wind turbine as described in claim 2, characterized in that: The steps to obtain the rate of change of frequency include: The change characteristics of the phase-locked frequency are extracted using the transfer function to obtain the initial frequency change rate; The initial frequency change rate is filtered to obtain the frequency change rate.

4. The method for suppressing frequency variation in a doubly-fed wind turbine as described in claim 3, characterized in that: The steps for acquiring control signals include: Based on the preset proportional parameters and time constant, the initial control signal is obtained by inputting the frequency change rate into the transfer function of the reactive power df / dt control algorithm; The control signal is obtained by performing a difference operation between the initial control signal and the per-unit value of the rated power.

5. The method for suppressing frequency variation in a doubly-fed wind turbine as described in claim 4, characterized in that: The steps for adjusting the internal potential component of the doubly-fed wind turbine include: The doubly fed fan uses the control signal to adjust the current command of the q-axis; The d-axis component of the dual-reverse fan is changed by controlling the change of the current command; When the rated active power is missing, the internal potential component is reduced by a factor of X; When the rated active power is excessive, the internal potential component increases by a factor of Y.

6. The method for suppressing frequency variation in a doubly-fed wind turbine as described in claim 5, characterized in that: The steps for controlling the power grid frequency include: Based on the change in internal potential, the power angle difference constraint between the internal potential of the doubly fed wind turbine and the grid voltage is adjusted; When the internal potential component is reduced by a factor of X, the power angle difference constraint is reduced to a factor of N. When the internal potential component increases by a factor of Y, the power angle difference constraint is expanded to a factor of M. The power grid frequency is controlled based on the adjusted power angle difference constraint.

7. The method for suppressing frequency variation in a doubly-fed wind turbine as described in claim 6, characterized in that: The steps for determining the output of the control signal include: When the frequency change trend of the power grid frequency changes from decreasing to increasing, or when the frequency change trend of the power grid frequency changes from increasing to decreasing, the output of the control signal ends. Otherwise, continue to output the control signal until the power grid frequency changes from a decrease to an increase or vice versa.

8. A doubly-fed induction generator (DFIG) frequency variation suppression system, employing the DFIG frequency variation suppression method as described in any one of claims 1 to 7, characterized in that, include: The phase-locked frequency calculation module collects detection data from the power grid where the doubly-fed wind turbine is located and calculates the phase-locked frequency based on the detection data. The frequency change rate calculation module calculates the frequency change rate of the power grid based on the phase-locked frequency and the transfer function. The control signal calculation module calculates and obtains the control signal based on the frequency change rate using the reactive power df / dt control algorithm. An internal potential component adjustment module adds the control signal to the current command of the doubly fed fan to adjust the internal potential component of the doubly fed fan. Adjust the power angle difference between the internal potential of the doubly-fed wind turbine and the grid terminal voltage according to the internal potential component, and control the grid frequency; The control signal control module controls the output of the control signal by judging the changing trend of the power grid frequency.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the doubly fed wind turbine frequency variation suppression method according to any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the doubly fed wind turbine frequency variation suppression method according to any one of claims 1 to 7.

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