Double-fed wind turbine control system, method, apparatus, storage medium and computer device

Abstract

The application discloses a kind of doubly-fed fan control system, method, device, storage medium and computer equipment, it is related to wind power generation technical field.Wherein, the system is used to control including doubly-fed generator and back-to-back converter doubly-fed fan, the system includes: support resistance circuit, its input end is connected with the stator end of doubly-fed generator, the output end of support resistance circuit is connected to the grid connection point corresponding to doubly-fed generator;DC support circuit, its first end is connected with the first end of DC side capacitor, the second end of DC support circuit is connected with the second end of DC side capacitor;System controller, with the control end of support resistance circuit and the control end of DC support circuit electrically connected, for controlling support resistance circuit provides stator end support voltage for doubly-fed generator, and control DC support circuit provides DC side support voltage for back-to-back converter.Above-mentioned system can effectively reduce the cost needed for wind power system to realize low voltage fault ride-through function.

Description

Technical Field

[0001] This invention relates to the field of wind power generation technology, and in particular to a doubly-fed wind turbine control system, method, apparatus, storage medium, and computer equipment. Background Technology

[0002] It is predicted that by 2025, the total installed capacity of new energy power generation systems in my country will reach 50% of the total installed capacity of the entire power generation system. As the main force of new energy in the power system, wind power will inevitably be vigorously developed.

[0003] In wind power systems, low-voltage fault ride-through (LFRT) is a critical capability required for wind turbines. This is especially true for wind power systems based on doubly fed induction generators (DFIGs), where the stator is directly connected to the grid connection point. When the grid voltage drops, both the stator voltage and the DC-side voltage decrease rapidly, severely impacting system stability and operational reliability. Therefore, a suitable LFRT is essential.

[0004] Currently, doubly-fed induction generators (DFIGs) typically employ parallel power electronic crowbars on the AC side or parallel power electronic choppers on the DC side to enable low-voltage fault ride-through capability. However, to avoid power system instability caused by excessive reactive power, both of these methods require the addition of extra reactive power equipment, such as statcoms and SVCs, to the wind power system, which significantly increases the cost of the wind power system. Summary of the Invention

[0005] In view of this, this application provides a doubly fed wind turbine control system, method, apparatus, storage medium and computer equipment, the main purpose of which is to solve the technical problem of high construction cost when wind power systems realize low voltage fault ride-through function.

[0006] According to a first aspect of the present invention, a doubly-fed induction generator (DFIG) control system is provided for controlling a DFIG, the DFIG including a DFIG generator and a back-to-back converter, the back-to-back converter including a generator-side converter, a grid-side converter, and a DC-side capacitor, the system comprising:

[0007] A voltage-supporting resistor circuit, wherein the input terminal of the voltage-supporting resistor circuit is connected to the stator terminal of the doubly-fed generator, and the output terminal of the voltage-supporting resistor circuit is connected to the grid connection point corresponding to the doubly-fed generator;

[0008] A DC voltage regulator circuit, wherein the first terminal of the DC voltage regulator circuit is connected to the first terminal of the DC-side capacitor, and the second terminal of the DC voltage regulator circuit is connected to the second terminal of the DC-side capacitor;

[0009] The system controller is electrically connected to the control terminal of the voltage-supporting resistor circuit and the control terminal of the DC voltage-supporting circuit, and is used to control the voltage-supporting resistor circuit to provide stator-side support voltage for the doubly-fed generator, and to control the DC voltage-supporting circuit to provide DC-side support voltage for the back-to-back converter.

[0010] According to a second aspect of the present invention, a doubly-fed wind turbine control method is provided, the method comprising:

[0011] Monitor the grid connection voltage at the grid connection point and compare the grid connection voltage with a preset grid connection voltage threshold;

[0012] If the grid-connected voltage is greater than or equal to the grid-connected voltage threshold, then the voltage-supporting resistor circuit is controlled to be in the conducting state, the DC voltage-supporting circuit is controlled to be in the disconnected state, and the generator-side converter is controlled to send the first direct-axis current and the first quadrature-axis current to the rotor end of the doubly-fed generator.

[0013] If the grid-connected voltage is less than the grid-connected voltage threshold, the voltage-supporting resistor circuit is controlled to be in the open state, the DC voltage-supporting circuit is controlled to be in the open state, and the generator-side converter is controlled to send a second direct-axis current and a second quadrature-axis current to the rotor end of the doubly-fed generator.

[0014] According to a third aspect of the present invention, a doubly fed fan control device is provided, the device comprising:

[0015] The condition judgment module is used to monitor the grid connection voltage of the grid connection point and compare the grid connection voltage with a preset grid connection voltage threshold.

[0016] The first current generation module is used to control the voltage-supporting resistor circuit to be in the conducting state, control the DC voltage-supporting circuit to be in the disconnected state, and control the generator-side converter to send the first direct-axis current and the first quadrature-axis current to the rotor end of the doubly-fed generator if the grid-connected voltage is greater than or equal to the grid-connected voltage threshold.

[0017] The second current generation module is used to control the voltage-supporting resistor circuit to be in the open state, control the DC voltage-supporting circuit to be in the open state, and control the generator-side converter to send a second direct-axis current and a second quadrature-axis current to the rotor end of the doubly-fed generator if the grid-connected voltage is less than the grid-connected voltage threshold.

[0018] According to a fourth aspect of the present invention, a storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the doubly fed fan control method described above.

[0019] According to a fifth aspect of the present invention, a computer device is provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the doubly fed fan control method described above.

[0020] This invention provides a doubly-fed induction generator (DFIG) wind turbine control system, method, apparatus, storage medium, and computer equipment. By setting a DC voltage-supporting circuit in parallel with the DC-side capacitor of the DFIG, the DC-side voltage of the DFIG can be maintained during low-voltage fault ride-through, improving the stability of the DFIG during this period. Simultaneously, by connecting a voltage-supporting resistor circuit in series between the stator terminals of the DFIG and the grid connection point, a voltage-supporting resistor circuit is generated at the voltage-supporting resistor circuit when the grid connection voltage drops, ensuring the stability of the stator terminal voltage, thereby improving the stability of the wind power system during low-voltage fault ride-through. Furthermore, since the stator terminal voltage of the DFIG is maintained by the voltage-supporting resistor circuit during low-voltage fault ride-through, the DFIG does not need to consume a large amount of reactive power to maintain the excitation voltage during low-voltage fault ride-through, effectively reducing the external reactive power compensation equipment required for the DFIG and lowering the construction cost of the wind power system.

[0021] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0022] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0023] Figure 1 This invention provides a schematic diagram of the structure of a conventional doubly-fed wind turbine according to an embodiment of the present invention;

[0024] Figure 2 A schematic diagram of a doubly fed fan control system provided in an embodiment of the present invention is shown;

[0025] Figure 3 A schematic diagram of a voltage-supporting resistor circuit provided in an embodiment of the present invention is shown;

[0026] Figure 4A schematic diagram of a DC voltage-boosting circuit provided in an embodiment of the present invention is shown;

[0027] Figure 5 A flowchart illustrating a doubly fed fan control method according to an embodiment of the present invention is shown.

[0028] Figure 6 This diagram illustrates the structure of a doubly fed fan control device according to an embodiment of the present invention.

[0029] Figure 7 A schematic diagram of another doubly fed fan control device provided in an embodiment of the present invention is shown. Detailed Implementation

[0030] The present invention will be described in detail below with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in the present application can be combined with each other.

[0031] In existing wind power systems, the low-voltage fault ride-through capability of doubly-fed induction generators is a critical requirement. Figure 1 A schematic diagram of an existing doubly-fed wind turbine is given, such as... Figure 1 As shown: Because the stator terminals of the doubly-fed generator 1 are directly connected to the grid connection point 2, when the voltage at the grid connection point 2 decreases, the stability and operational reliability of the power system will be severely affected. Simultaneously, when the voltage at the grid connection point 2 decreases, the DC-side voltage at the back-to-back converter 3 will also drop sharply, further reducing the stability and operational reliability of the power system.

[0032] To address the above problems, in one embodiment, such as Figure 2 As shown, a doubly-fed induction generator (DFIG) control system is provided for controlling a DFIG. The DFIG includes a DFIG generator 100 and a back-to-back converter 400. The back-to-back converter 400 includes a generator-side converter 410, a grid-side converter 420, and a DC-side capacitor 430. The system includes:

[0033] A voltage-stabilizing resistor circuit 200 is included, with its input terminal connected to the stator terminal of the doubly-fed generator 100 and its output terminal connected to the grid connection point 300 corresponding to the doubly-fed generator 100. It should be noted that most existing doubly-fed wind turbines employ three-phase power transmission. In three-phase mode, each phase of the transmission line is connected to a voltage-stabilizing resistor circuit 200 to stabilize the stator voltage. Similarly, other transmission methods are also applicable to this embodiment, and will not be elaborated upon here.

[0034] The voltage-supporting resistor circuit 200 can include transmission lines with and without additional resistors. The voltage-supporting resistor circuit 200 can be controlled to use either the transmission line with or without additional resistors as the transmission line for the doubly-fed generator 100 to supply power to the grid connection point 300. Furthermore, when the transmission line with additional resistors is used as the transmission line for the doubly-fed generator 100 to supply power to the grid connection point 300, the excitation current generated by the doubly-fed generator 100 can be used to generate a supporting voltage across the additional resistor, thereby stabilizing the voltage at the stator terminals.

[0035] A DC voltage regulator circuit 440 is provided, wherein the first end of the DC voltage regulator circuit 440 is connected to the first end of the DC-side capacitor 430, and the second end of the DC voltage regulator circuit 440 is connected to the second end of the DC-side capacitor 430.

[0036] The DC voltage support circuit 440 may include a support resistor and a switch controller, which can control whether the support resistor is connected in parallel to the DC-side capacitor 430. Furthermore, when the support resistor is connected in parallel to the DC-side capacitor 430, it can provide a support voltage for the DC-side voltage of the back-to-back converter.

[0037] The system controller (not shown in the figure) is electrically connected to the control terminal of the voltage-supporting resistor circuit 200 and the control terminal of the DC voltage-supporting circuit 440. It is used to control the voltage-supporting resistor circuit 200 to provide stator-side support voltage for the doubly-fed generator and to control the DC voltage-supporting circuit 440 to provide DC-side support voltage for the back-to-back converter 400.

[0038] Specifically, when the voltage at grid connection point 300 drops sharply, the system controller can use a transmission line with an additional resistor as the transmission line for the doubly-fed generator 100 to supply power to grid connection point 300. This allows the additional resistor to provide stator support voltage to the stator terminals of the doubly-fed generator 100, ensuring stator voltage stability. Simultaneously, the system controller can also control the DC voltage support circuit 440 to connect the support resistor in parallel to the DC-side capacitor 430, providing DC-side support voltage to the back-to-back converter 400, ensuring DC-side voltage stability, and thus giving the doubly-fed wind turbine a strong low-voltage fault ride-through capability. It should be noted that if the doubly-fed wind turbine uses a multi-phase transmission configuration, the system controller can control the voltage support resistor circuit 200 corresponding to each phase of power supply to give the doubly-fed wind turbine a strong low-voltage fault ride-through capability.

[0039] In this embodiment, by providing a DC voltage-supporting circuit connected in parallel to the DC-side capacitor of the doubly-fed generator (DFIG), the DC-side voltage of the DFIG can be maintained during low-voltage fault ride-through, improving the stability of the DFIG during this period. Simultaneously, by connecting a voltage-supporting resistor circuit in series between the stator terminals of the DFIG and the grid connection point, voltage support is generated at the voltage-supporting resistor circuit when the grid connection voltage drops, ensuring the stability of the stator terminal voltage and thus improving the stability of the wind power system during low-voltage fault ride-through. Furthermore, since the stator terminal voltage of the DFIG is maintained by the voltage-supporting resistor circuit during low-voltage fault ride-through, the DFIG does not need to consume a large amount of reactive power to maintain the excitation voltage during this period, effectively reducing the external reactive power compensation equipment required for the DFIG and lowering the construction cost of the wind power system.

[0040] In one embodiment, see Figure 3 , Figure 3 A schematic diagram of the voltage-supporting resistor circuit is provided: The voltage-supporting resistor circuit 200 includes a voltage-supporting resistor 210 and a first switch 220. The first end of the voltage-supporting resistor 210 and the first end of the first switch 220 are connected in parallel to the input terminal of the voltage-supporting resistor circuit 200 to connect to the stator terminal of the doubly-fed generator 100. The second end of the voltage-supporting resistor 210 and the second end of the first switch 220 are connected in parallel to the output terminal of the voltage-supporting resistor circuit 200 to connect to the grid connection point 300. The control terminal of the first switch 220 is electrically connected to the first output terminal of the system controller (not shown in the figure). The first switch 220 is controlled by the system controller to open and close. Furthermore, when the voltage at grid connection point 300 is normal, the system controller can control the first switch 220 to conduct, so that the voltage-supporting resistor 210 is short-circuited, and the output power of the doubly-fed generator 100 will be directly transmitted to grid connection point 300. Conversely, when the voltage at grid connection point 300 drops sharply, the system controller can control the first switch 220 to open, so that the voltage-supporting resistor 210 is connected to the power transmission line between the doubly-fed generator 100 and grid connection point 300, so that the excitation current at the stator end generates a voltage across the voltage-supporting resistor 210, thereby stabilizing the voltage at the stator end. In the embodiments of this application, by connecting a voltage-supporting resistor circuit in series between the stator end of the doubly-fed generator and the grid connection point, when the grid connection voltage drops, the direct-axis and quadrature-axis currents generated at the rotor end can be used to generate an excitation current at the stator end, and a voltage-supporting resistor circuit can be generated to ensure the stability of the stator end voltage, thereby improving the stability of the wind power system during low-voltage fault ride-through.

[0041] In one embodiment, see Figure 4 , Figure 4A schematic diagram of the DC voltage-supporting circuit is provided: In the back-to-back converter 400, the DC voltage-supporting circuit 440 includes a supporting resistor 442 and a second switch 441. The supporting resistor 442 and the second switch 441 are connected in series between the first and second terminals of the DC voltage-supporting circuit 440. The control terminal of the second switch 441 is electrically connected to the second output terminal of the system controller (not shown in the figure). The second switch 441 is controlled by the system controller to open and close. Furthermore, when the grid voltage is normal, the system controller can control the second switch 441 to open, thus disconnecting the supporting resistor 442 from the back-to-back converter 400. Correspondingly, when the voltage at the grid connection point drops sharply, the system controller can control the second switch 441 to turn on, connecting the DC voltage-supporting circuit 440 in parallel with the DC-side capacitor 430. This allows the supporting resistor 442 to generate voltage under the influence of the current between the generator-side converter 410 and the grid-side converter 420, thereby stabilizing the DC-side voltage of the back-to-back converter 400. In the embodiments of this application, by providing a DC voltage-supporting circuit connected in parallel with the DC-side capacitor of the doubly-fed generator, the DC-side voltage of the doubly-fed generator can be maintained during low-voltage fault ride-through, improving the stability of the doubly-fed generator during low-voltage fault ride-through.

[0042] The doubly-fed induction generator (DFIG) wind turbine control system provided in this embodiment connects a voltage-supporting resistor circuit in series with each phase of the transmission line between the stator of the DFIG generator and the grid connection point. A first switch controls whether to use the line with the voltage-supporting resistor as the transmission line between the stator of the DFIG generator and the grid connection point. When the grid voltage drops sharply, the line with the voltage-supporting resistor is used as the transmission line between the stator of the DFIG generator and the grid connection point. The direct-axis and quadrature-axis currents generated at the rotor end induce an excitation current at the stator end, generating voltage support at the voltage-supporting resistor circuit, ensuring the stability of the stator voltage and thus improving the stability of the wind power system during low-voltage fault ride-through. Furthermore, because the stator voltage of the DFIG generator is maintained by the voltage-supporting resistor circuit during low-voltage fault ride-through, the voltage at the stator end is further maintained during this period. Furthermore, by setting up a DC voltage-supporting circuit connected in parallel with the DC-side capacitor of the doubly-fed generator (DFIG), and controlling the on / off state of the second switch in the DC voltage-supporting circuit by the system controller, the supporting resistor is connected to the back-to-back converter. This allows the DC-side voltage of the DFIG to be maintained during low-voltage fault ride-through, improving the stability of the DFIG during this period. Therefore, the DFIG does not need to consume a large amount of reactive power to maintain the excitation voltage during low-voltage fault ride-through, effectively reducing the external reactive power compensation equipment required for the DFIG and lowering the construction cost of the wind power system.

[0043] In one embodiment, such as Figure 5As shown, a doubly-fed induction generator (DFIG) control method is provided, which is applied to the system controller of a DFIG control system, and includes the following steps:

[0044] 501. Monitor the grid connection voltage at the grid connection point and compare the grid connection voltage with a preset grid connection voltage threshold.

[0045] Among them, the grid connection voltage threshold can be used to determine whether a low voltage fault has occurred in the power grid system. When the grid connection voltage is greater than or equal to the grid connection voltage threshold, it can be determined that the grid connection voltage is in a normal state; while when the grid connection voltage is less than the grid connection voltage threshold, it can be determined that a low voltage fault has occurred in the power system.

[0046] Specifically, the grid connection voltage at the grid connection point can be acquired in real time or periodically and compared with a preset grid connection voltage threshold. The value of the grid connection voltage threshold can be set according to the actual situation.

[0047] 502. If the grid connection voltage is greater than or equal to the grid connection voltage threshold, then control the voltage-supporting resistor circuit to be in the conducting state, control the DC voltage-supporting circuit to be in the disconnected state, and control the generator-side converter to send the first direct-axis current and the first quadrature-axis current to the rotor end of the doubly-fed generator.

[0048] Specifically, when the grid-connected voltage is greater than or equal to the grid-connected voltage threshold, the supporting resistor circuit can be turned on by turning on the first switch, thus short-circuiting the supporting resistor and allowing the output power of the doubly-fed generator to be directly transmitted to the grid connection point through the transmission line. Furthermore, the supporting resistor can be disconnected from the back-to-back converter by turning on the second switch of the DC supporting circuit, allowing the back-to-back converter to generate DC-side voltage normally. Further, the generator-side converter sends a first direct-axis current to the rotor of the doubly-fed generator according to a preset active power reference value, so that the stator of the doubly-fed generator, under the action of the rotor with the first direct-axis current, sends active power to the grid connection point equal to the active power reference value. Simultaneously, the generator-side converter sends a first quadrature-axis current to the rotor of the doubly-fed generator according to a preset grid-connected voltage reference value, so that the stator of the doubly-fed generator, under the action of the rotor with the first quadrature-axis current, sends an excitation voltage to the grid connection point equal to the grid-connected voltage reference value.

[0049] The active power reference value can be a preset active power value that the doubly-fed induction generator (DFIG) should provide to the grid connection point during normal power system operation, while the grid connection voltage reference value can be the excitation voltage that the DFIG should provide to the grid connection point during normal power system operation. Furthermore, the excitation voltage generated at the stator terminals of the DFIG can be used to generate the voltage value required for the power system grid connection point through a step-up transformer. Specifically, the active power reference value and the grid connection voltage reference value can be determined based on actual conditions.

[0050] 503. If the grid-connected voltage is less than the grid-connected voltage threshold, the voltage-supporting resistor circuit is controlled to be in the open state, the DC voltage-supporting circuit is controlled to be in the on state, and the generator-side converter is controlled to send the second direct-axis current and the second quadrature-axis current to the rotor end of the doubly-fed generator.

[0051] Specifically, when the grid-connected voltage is lower than the grid-connected voltage threshold, a low-voltage fault can be identified in the power system. In this case, the voltage-supporting resistor circuit can be disconnected by turning off the first switch, allowing it to connect to the power transmission line between the doubly-fed generator (DFIG) and the grid connection point. This causes the excitation current at the stator end to generate a voltage across the voltage-supporting resistor, thereby stabilizing the stator voltage. Simultaneously, the generator-side converter can send a second direct-axis current to the rotor end of the DFIG, causing the stator end of the DFIG to send active power to the grid connection point at the same level as the preset active power protection value under the influence of the rotor end carrying the second direct-axis current. The active power protection value is used to calibrate the active power that the DFIG should send to the grid connection point when a low-voltage fault occurs in the power system. The active power protection value is usually lower than the active power reference value; under normal circumstances, the active power protection value can be set to zero to minimize the fault current. The specific value of the active power protection value can be determined according to the actual situation. Simultaneously, a second quadrature-axis current is sent to the rotor end of the doubly-fed generator (DFIG) according to the preset grid-connected voltage protection value via the generator-side converter. This causes the stator end of the DFIG to generate an excitation current under the influence of the second quadrature-axis current. The voltage-supporting resistors then generate a voltage under the action of the excitation current, compensating for the stator excitation voltage and ensuring that the stator excitation voltage is equal to the grid-connected voltage protection value. This, in turn, ensures the stability of the stator voltage of the DFIG. The grid-connected voltage protection value is the voltage that the stator end of the DFIG should have when a low-voltage fault occurs in the power system, enabling the DFIG to have low-voltage ride-through capability. The value of the grid-connected voltage protection value is usually lower than the grid-connected voltage reference value, and the specific value can be determined based on actual conditions.

[0052] Furthermore, when the grid-connected voltage is less than the grid-connected voltage threshold, the second switch of the DC voltage-supporting circuit can be turned on to connect the supporting resistor in the DC voltage-supporting circuit in parallel with the DC-side capacitor. This allows the supporting resistor to generate voltage under the current action between the machine-side converter and the grid-side converter, thereby stabilizing the DC-side voltage of the back-to-back converters.

[0053] The doubly-fed induction generator (DFIG) control method provided in this embodiment enables the DFIG to achieve the same power generation capacity as existing DFIGs by adjusting the structure of the voltage-supporting resistor circuit and the DC voltage-supporting circuit when the power system is in a normal state. When a low-voltage fault occurs in the power system, the voltage-supporting resistor and the supporting resistor can be connected to the DFIG system. Under the control of the direct-axis current and quadrature-axis current at the rotor end, the stator voltage and DC-side voltage are stabilized, improving the stability of the DFIG generator during low-voltage fault ride-through.

[0054] In one embodiment, the method for controlling the generator-side converter to send the first direct-axis current to the rotor end of the doubly-fed generator in step 502 is as follows: First, monitor the first real-time active power output of the doubly-fed generator and calculate the first difference between a preset active power reference value and the first real-time active power. The first real-time active power is the active power sent by the doubly-fed generator to the grid connection point when no low-voltage fault occurs in the power system. Then, input the first difference into a first proportional-integral controller to obtain the first direct-axis current reference value, and send the first direct-axis current reference value to the generator-side converter, so that the generator-side converter generates the first direct-axis current based on the first direct-axis current reference value and sends the first direct-axis current to the rotor end of the doubly-fed generator. Specifically, a first proportional-integral controller is installed in the existing control system of the generator-side converter. It receives the active power reference value and the current first real-time active power, and calculates the first difference between the active power reference value and the first real-time active power. Subsequently, the first proportional-integral controller generates a first direct-axis current reference value based on the first difference. Then, it sends the first direct-axis current reference value to the inner-loop current controller in the control system of the generator-side converter, so that the inner-loop current controller sends a pulse signal to the generator-side converter based on the first direct-axis current reference value. Finally, after receiving the above pulse signal, the generator-side converter generates a first direct-axis current corresponding to the first direct-axis current reference value and sends the first direct-axis current to the rotor end of the doubly-fed generator to adjust the active power generated at the stator end of the doubly-fed generator. The first proportional-integral controller continuously acquires the first difference value and adjusts the first direct-axis current reference value to change the first direct-axis current sent from the machine-side converter to the rotor end. This adjusts the first real-time active power generated at the stator end, bringing the value of the first real-time active power closer to the active power reference value, thereby reducing the difference between the active power reference value and the real-time active power. Ultimately, this ensures that the stator end generates active power identical to the active power reference value under the action of the first direct-axis current.

[0055] Furthermore, the implementation method of controlling the generator-side converter to send the first quadrature-axis current to the rotor end of the doubly-fed generator in step 502 is as follows: First, monitor the first real-time excitation voltage output by the doubly-fed generator and calculate the second difference between a preset grid-connected voltage reference value and the first real-time excitation voltage. The first real-time excitation voltage is the excitation voltage sent by the doubly-fed wind turbine to the grid connection point when no low-voltage fault occurs in the power system. Then, input the second difference into the second proportional-integral controller to obtain the first quadrature-axis current reference value, and send the first quadrature-axis current reference value to the generator-side converter, so that the generator-side converter generates the first quadrature-axis current according to the first quadrature-axis current reference value and sends the first quadrature-axis current to the rotor end of the doubly-fed generator. Specifically, the second proportional-integral controller is installed in the existing control system of the generator-side converter. It receives a preset grid-connected voltage reference value and the current first real-time excitation voltage, and calculates a second difference between the grid-connected voltage reference value and the first real-time excitation voltage. Subsequently, the second proportional-integral controller generates a first quadrature-axis current reference value based on the second difference. Then, it sends the first quadrature-axis current reference value to the inner loop current controller in the control system of the generator-side converter, so that the inner loop current controller sends a pulse signal to the generator-side converter based on the first quadrature-axis current reference value. Finally, after receiving the above pulse signal, the generator-side converter generates a first quadrature-axis current corresponding to the first quadrature-axis current reference value and sends the first quadrature-axis current to the rotor end of the doubly-fed generator to adjust the excitation voltage generated at the stator end of the doubly-fed generator. The second proportional-integral controller continuously acquires the second difference value and adjusts the first quadrature-axis current reference value to change the first quadrature-axis current sent from the machine-side converter to the rotor end. This adjusts the first real-time excitation voltage generated at the stator end, bringing its value closer to the grid-connected voltage reference value, thereby reducing the difference between the grid-connected voltage reference value and the first real-time excitation voltage. Ultimately, under the action of the first quadrature-axis current, the stator end generates an excitation voltage identical to the grid-connected voltage reference value.

[0056] In the embodiments of this application, the direct-axis current and quadrature-axis current sent to the rotor end are adjusted by the first proportional-integral controller and the second proportional-integral controller in the generator-side converter, so that the stator end generates active power and excitation voltage that meet the preset standard under the action of the rotor end, thus ensuring the power output capability of the doubly-fed wind turbine when the power system is in a normal state.

[0057] In one embodiment, the method for controlling the generator-side converter to send the second direct-axis current to the rotor end of the doubly-fed generator in step 503 is as follows: First, monitor the second real-time active power output of the doubly-fed generator and calculate the third difference between the preset active power protection value and the second real-time active power. The second real-time active power is the active power sent by the doubly-fed generator to the grid connection point when a low-voltage fault occurs in the power system. Then, input the third difference into the third proportional-integral controller to obtain a second direct-axis current reference value, and send the second direct-axis current reference value to the generator-side converter, so that the generator-side converter generates a second direct-axis current based on the second direct-axis current reference value and sends the second direct-axis current to the rotor end of the doubly-fed generator. Specifically, a third proportional-integral controller is installed in the existing generator-side converter control system to receive the active power protection value and the current second real-time active power, and calculate a third difference between the active power protection value and the second real-time active power. Subsequently, the third proportional-integral controller generates a second direct-axis current reference value based on the third difference. Then, it sends the second direct-axis current reference value to the inner-loop current controller in the generator-side converter control system, so that the inner-loop current controller sends a pulse signal to the generator-side converter based on the second direct-axis current reference value. Finally, after receiving the above pulse signal, the generator-side converter generates a second direct-axis current corresponding to the second direct-axis current reference value and sends the second direct-axis current to the rotor end of the doubly-fed generator to adjust the active power generated at the stator end of the doubly-fed generator. The third proportional-integral controller continuously acquires the third difference value and adjusts the second direct-axis current reference value to change the second direct-axis current sent from the machine-side converter to the rotor end. This adjusts the second real-time active power generated at the stator end, bringing the value of the second real-time active power closer to the active power protection value, thereby reducing the difference between the active power protection value and the second real-time active power. Ultimately, under the action of the second direct-axis current, the stator end generates active power that is the same as the active power protection value.

[0058] Furthermore, the implementation method of controlling the generator-side converter to send the second quadrature-axis current to the rotor end of the doubly-fed generator in step 503 is as follows: First, monitor the second real-time excitation voltage output by the doubly-fed generator and calculate the fourth difference between the preset grid-connected voltage protection value and the second real-time excitation voltage. The second real-time excitation voltage is the excitation voltage at the stator end of the doubly-fed generator when a low-voltage fault occurs in the power system. Then, input the fourth difference into the fourth proportional-integral controller to obtain a second quadrature-axis current reference value, and send the second quadrature-axis current reference value to the generator-side converter, so that the generator-side converter generates the second quadrature-axis current according to the second quadrature-axis current reference value and sends the second quadrature-axis current to the rotor end of the doubly-fed generator. Specifically, the fourth proportional-integral controller is installed in the existing generator-side converter control system. It receives the preset grid-connected voltage protection value and the current second real-time excitation voltage, and calculates the fourth difference between the grid-connected voltage protection value and the second real-time excitation voltage. Subsequently, the fourth proportional-integral controller generates a second quadrature-axis current reference value based on the fourth difference. Then, it sends the second quadrature-axis current reference value to the inner loop current controller in the generator-side converter control system, so that the inner loop current controller sends a pulse signal to the generator-side converter based on the second quadrature-axis current reference value. Finally, after receiving the above pulse signal, the generator-side converter generates a second quadrature-axis current corresponding to the second quadrature-axis current reference value and sends the second quadrature-axis current to the rotor end of the doubly-fed generator to adjust the excitation current generated at the stator end of the doubly-fed generator. Furthermore, the excitation current generates a voltage through the voltage-supporting resistor, thereby compensating for the excitation voltage at the stator end. The fourth proportional-integral controller continuously acquires the fourth difference value and adjusts the second quadrature-axis current to change the second quadrature-axis current sent from the turbine-side converter to the rotor end. This changes the excitation current at the stator end, thereby altering the second real-time excitation voltage at the stator end. The goal is to bring the value of the second real-time excitation voltage closer to the grid-connected voltage protection value, thus reducing the difference between the grid-connected voltage protection value and the second real-time excitation voltage. Ultimately, this ensures that the excitation voltage, after voltage compensation through the voltage-supporting resistor, is identical to the grid-connected voltage protection value.

[0059] In the embodiments of this application, the direct-axis current and quadrature-axis current sent to the rotor end are adjusted by the third proportional-integral controller and the fourth proportional-integral controller in the generator-side converter, so that the stator end generates active power and excitation voltage that meet the preset standard when a low voltage fault occurs in the power system under the action of the rotor end, thereby ensuring the low voltage fault ride-through capability of the doubly-fed wind turbine when a low voltage fault occurs in the power system.

[0060] In one embodiment, the doubly-fed induction generator (DFIG) control method may further include the following steps: First, monitoring the real-time DC-side voltage of the back-to-back converter and calculating a fifth difference between a preset DC-side voltage reference value and the real-time DC-side voltage. The DC-side voltage reference value can be the DC-side voltage that the DFIG is expected to achieve during operation, and its value can be determined based on actual conditions. Then, the fifth difference is input into a fifth proportional-integral controller to obtain a third direct-axis current reference value, and this third direct-axis current reference value is sent to the grid-side converter so that the grid-side converter generates a third direct-axis current based on the third direct-axis current reference value. Specifically, a fifth proportional-integral controller (PIC) is installed in the grid-side converter's control system. It receives the DC-side voltage reference value and the current real-time DC-side voltage, and calculates the fifth difference between them. Subsequently, the PIC generates a third direct-axis current reference value based on this fifth difference. This third direct-axis current reference value is then sent to the inner-loop current controller in the grid-side converter's control system, causing the inner-loop current controller to send a pulse signal to the grid-side converter based on the third direct-axis current reference value. Finally, upon receiving the pulse signal, the grid-side converter generates a third direct-axis current corresponding to the third direct-axis current reference value to adjust the DC-side voltage of the doubly-fed induction generator (DFIG). By continuously acquiring the fifth difference and adjusting the third direct-axis current reference value, the PIC changes the third direct-axis current emitted by the grid-side converter, thereby adjusting the DC-side voltage of the DFIG and bringing the real-time DC-side voltage value closer to the DC-side voltage reference value, thus reducing the difference between the reference value and the real-time DC-side voltage. Ultimately, the doubly fed wind turbine generates a DC-side voltage that is identical to the DC-side voltage reference value under the action of the third direct-axis current.

[0061] Furthermore, the above-mentioned doubly-fed induction generator (DFIG) control method may also include the following steps: First, monitor the real-time reactive power at the grid connection point and calculate the sixth difference between a preset reactive power reference value and the real-time reactive power. The reactive power reference value can be the reactive power to be output by the DFIG during operation, and its value can be determined according to actual conditions. Then, input the sixth difference into the sixth proportional-integral controller to obtain a third quadrature-axis current reference value, and send the third quadrature-axis current reference value to the grid-side converter so that the grid-side converter generates a third quadrature-axis current based on the third quadrature-axis current reference value. Specifically, the sixth proportional-integral controller (PIC) is installed in the grid-side converter's control system. It receives a preset reactive power reference value and the current real-time reactive power, and calculates the sixth difference between the reference value and the real-time reactive power. Subsequently, the PIC generates a third quadrature-axis current reference value based on this sixth difference. This third quadrature-axis current reference value is then sent to the inner-loop current controller in the grid-side converter's control system, causing the inner-loop current controller to send a pulse signal to the grid-side converter based on the third quadrature-axis current reference value. Finally, upon receiving the pulse signal, the grid-side converter generates a third quadrature-axis current corresponding to the reference value, thereby adjusting the reactive power of the doubly-fed induction generator (DFIG). By continuously acquiring the sixth difference and adjusting the third quadrature-axis current, the PIC changes the third quadrature-axis current emitted by the grid-side converter, thus adjusting the reactive power of the DFIG and bringing the real-time reactive power value closer to the reference value, thereby reducing the difference between the reference value and the real-time reactive power. Ultimately, the doubly fed wind turbine generates reactive power that is the same as the reactive power reference value under the action of the third quadrature axis current.

[0062] The doubly-fed induction generator (DFIG) wind turbine control method provided in this embodiment enables the DFIG wind turbine to achieve the same power generation capacity as existing DFIG wind turbines when the power system is in a normal state by adjusting the structure of the voltage-supporting resistor circuit and the DC voltage-supporting circuit. The proportional-integral (PI) controller on the turbine-side converter ensures that the active power and excitation voltage of the DFIG wind turbine reach the preset standards for a normal power system. When a low-voltage fault occurs in the power system, the voltage-supporting resistor and the supporting resistor can be connected to the DFIG wind turbine system. Under the control of the direct-axis current and quadrature-axis current at the rotor end, the stator voltage and DC-side voltage are stabilized. The PI controller on the turbine-side converter ensures that the active power and excitation voltage of the DFIG wind turbine reach the preset standards for a low-voltage fault state. Simultaneously, the PI controller on the grid-side converter ensures that the reactive power and DC-side voltage of the DFIG wind turbine reach preset standards. Furthermore, this means that the doubly-fed generator does not need to consume a large amount of reactive power to maintain the excitation voltage during low-voltage fault ride-through, which can effectively reduce the external reactive power compensation equipment required for the doubly-fed generator, reduce the construction cost of the wind power system, and improve the stability of the doubly-fed generator during low-voltage fault ride-through.

[0063] Furthermore, as Figure 5 The specific implementation of the method shown in this embodiment provides a doubly fed wind turbine control device, such as... Figure 6 As shown, the device includes: a condition judgment module 61, a first current generation module 62, and a second current generation module 63.

[0064] The condition judgment module 61 can be used to monitor the grid connection voltage of the grid connection point and compare the grid connection voltage with a preset grid connection voltage threshold.

[0065] The first current generation module 62 can be used to control the first switch of the voltage-supporting resistor circuit to be in the conducting state, control the second switch of the DC voltage-supporting circuit to be in the disconnected state, and control the generator-side converter to send the first direct-axis current and the first quadrature-axis current to the rotor end of the doubly-fed generator if the grid voltage is greater than or equal to the grid voltage threshold.

[0066] The second current generation module 63 can be used as a second current generation module to control the first switch of the voltage-supporting resistor circuit to be in the open state, control the second switch of the DC voltage-supporting circuit to be in the on state, and control the generator-side converter to send a second direct-axis current and a second quadrature-axis current to the rotor end of the doubly-fed generator if the grid-connected voltage is less than the grid-connected voltage threshold.

[0067] In a specific application scenario, the first current generation module 62 can be used to monitor the first real-time active power output of the doubly-fed generator and calculate a first difference between a preset active power reference value and the first real-time active power; input the first difference into a first proportional-integral controller to obtain a first direct-axis current reference value, and send the first direct-axis current reference value to the generator-side converter so that the generator-side converter generates a first direct-axis current based on the first direct-axis current reference value and sends the first direct-axis current to the rotor end of the doubly-fed generator; monitor the first real-time excitation voltage output of the doubly-fed generator and calculate a second difference between a preset grid-connected voltage reference value and the first real-time excitation voltage; input the second difference into a second proportional-integral controller to obtain a first quadrature-axis current reference value, and send the first quadrature-axis current reference value to the generator-side converter so that the generator-side converter generates a first quadrature-axis current based on the first quadrature-axis current reference value and sends the first quadrature-axis current to the rotor end of the doubly-fed generator.

[0068] In a specific application scenario, the second current generation module 63 can be used to monitor the second real-time active power output of the doubly-fed generator, and calculate a third difference between a preset active power protection value and the second real-time active power; input the third difference into a third proportional-integral controller to obtain a second direct-axis current reference value, and send the second direct-axis current reference value to the generator-side converter, so that the generator-side converter generates a second direct-axis current based on the second direct-axis current reference value, and sends the second direct-axis current to the rotor end of the doubly-fed generator; monitor the second real-time excitation voltage output of the doubly-fed generator, and calculate a fourth difference between a preset grid-connected voltage protection value and the second real-time excitation voltage; input the fourth difference into a fourth proportional-integral controller to obtain a second quadrature-axis current reference value, and send the second quadrature-axis current reference value to the generator-side converter, so that the generator-side converter generates a second quadrature-axis current based on the second quadrature-axis current reference value, and sends the second quadrature-axis current to the rotor end of the doubly-fed generator.

[0069] In specific application scenarios, such as Figure 7As shown, this device also includes a third current generation module 74. Specifically, the third current generation module 74 can be used to monitor the real-time DC-side voltage of the back-to-back converter and calculate a fifth difference between a preset DC-side voltage reference value and the real-time DC-side voltage; input the fifth difference into a fifth proportional-integral controller to obtain a third direct-axis current reference value, and send the third direct-axis current reference value to the grid-side converter so that the grid-side converter generates a third direct-axis current based on the third direct-axis current reference value; monitor the real-time reactive power at the grid connection point and calculate a sixth difference between a preset reactive power reference value and the real-time reactive power; input the sixth difference into a sixth proportional-integral controller to obtain a third quadrature-axis current reference value, and send the third quadrature-axis current reference value to the grid-side converter so that the grid-side converter generates a third quadrature-axis current based on the third quadrature-axis current reference value.

[0070] It should be noted that other corresponding descriptions of the functional units involved in the doubly fed fan control device provided in this embodiment can be found in the corresponding descriptions in section 5, and will not be repeated here.

[0071] Based on the above, Figure 5 Accordingly, this embodiment also provides a storage medium storing a computer program that, when executed by a processor, implements the above-described method. Figure 5 The doubly fed fan control method is shown.

[0072] Based on this understanding, the technical solution of this application can be embodied in the form of a software product. The software product to be identified can be stored in a non-volatile storage medium (such as a CD-ROM, USB flash drive, or portable hard drive), including several instructions to cause a computer device (such as a personal computer, server, or network device) to execute the methods described in the various implementation scenarios of this application.

[0073] Based on the above, Figure 5 The method shown, and Figure 6 and Figure 7 The illustrated doubly-fed induction generator (DFIG) control device embodiment further provides a physical device for controlling the DFIG to achieve the above objectives. This physical device can be a personal computer, server, smartphone, tablet, smartwatch, or other network device, etc. The physical device includes a storage medium and a processor; the storage medium stores a computer program; the processor executes the computer program to achieve the above-described objectives. Figure 5 The method shown.

[0074] Optionally, the physical device may also include a user interface, a network interface, a camera, radio frequency (RF) circuitry, sensors, audio circuitry, a Wi-Fi module, etc. The user interface may include a display screen, input units such as a keyboard, etc., and optional user interfaces may also include USB interfaces, card reader interfaces, etc. The network interface may optionally include standard wired interfaces, wireless interfaces (such as Wi-Fi interfaces), etc.

[0075] Those skilled in the art will understand that the physical device structure for controlling a doubly fed fan provided in this embodiment does not constitute a limitation on the physical device, and may include more or fewer components, or combine certain components, or have different component arrangements.

[0076] The storage medium may also include an operating system and a network communication module. The operating system is a program that manages the hardware and software resources of the aforementioned physical device, supporting the operation of information processing programs and other software and / or programs to be identified. The network communication module is used to enable communication between the various components within the storage medium, as well as communication with other hardware and software in the information processing physical device.

[0077] Through the above description of the embodiments, those skilled in the art can clearly understand that this application can be implemented by means of software plus necessary general-purpose hardware platform, or it can be implemented by hardware. By applying the technical solution of this application, firstly, the grid connection voltage of the grid connection point is monitored, and the grid connection voltage is compared with a preset grid connection voltage threshold; then, if the grid connection voltage is greater than or equal to the grid connection voltage threshold, the voltage-supporting resistor circuit is controlled to be in the conducting state, the DC voltage-supporting circuit is controlled to be in the disconnected state, and the generator-side converter is controlled to send a first direct-axis current and a first quadrature-axis current to the rotor end of the doubly-fed generator; then, if the grid connection voltage is less than the grid connection voltage threshold, the voltage-supporting resistor circuit is controlled to be in the disconnected state, the DC voltage-supporting circuit is controlled to be in the conducting state, and the generator-side converter is controlled to send a second direct-axis current and a second quadrature-axis current to the rotor end of the doubly-fed generator. Compared with existing technologies, this technology enables doubly-fed generators to maintain excitation voltage without consuming a large amount of reactive power during low-voltage fault ride-through. This effectively reduces the need for external reactive power compensation equipment for doubly-fed generators, lowers the construction cost of wind power systems, and improves the stability of doubly-fed generators during low-voltage fault ride-through.

[0078] Those skilled in the art will understand that the accompanying drawings are merely schematic diagrams of a preferred embodiment, and the modules or processes shown in the drawings are not necessarily essential for implementing this application. Those skilled in the art will understand that the modules in the apparatus of the embodiment can be distributed within the apparatus of the embodiment as described, or can be modified to be located in one or more apparatuses different from this embodiment. The modules of the above-described embodiment can be combined into one module, or further divided into multiple sub-modules.

[0079] The serial numbers in this application are for descriptive purposes only and do not represent the superiority or inferiority of any particular implementation scenario. The above disclosures are merely a few specific implementation scenarios of this application; however, this application is not limited thereto, and any variations conceived by those skilled in the art should fall within the protection scope of this application.

Claims

1. A doubly-fed induction generator (DFIG) control system for controlling a DFIG, wherein the DFIG includes a DFIG generator and a back-to-back converter, and the back-to-back converter includes a generator-side converter, a grid-side converter, and a DC-side capacitor, characterized in that... The system includes: A voltage-supporting resistor circuit, wherein the input terminal of the voltage-supporting resistor circuit is connected to the stator terminal of the doubly-fed generator, and the output terminal of the voltage-supporting resistor circuit is connected to the grid connection point corresponding to the doubly-fed generator; A DC voltage regulator circuit, wherein the first terminal of the DC voltage regulator circuit is connected to the first terminal of the DC-side capacitor, and the second terminal of the DC voltage regulator circuit is connected to the second terminal of the DC-side capacitor; The system controller is electrically connected to the control terminal of the voltage-supporting resistor circuit and the control terminal of the DC voltage-supporting circuit, and is used to control the voltage-supporting resistor circuit to provide stator-side support voltage for the doubly-fed generator, and to control the DC voltage-supporting circuit to provide DC-side support voltage for the back-to-back converter. The voltage-supporting resistor circuit includes a voltage-supporting resistor and a first switch. The first end of the voltage-supporting resistor and the first end of the first switch are connected in parallel to the input terminal of the voltage-supporting resistor circuit. The second end of the voltage-supporting resistor and the second end of the first switch are connected in parallel to the output terminal of the voltage-supporting resistor circuit. The control terminal of the first switch is electrically connected to the first output terminal of the system controller. The DC voltage-supporting circuit includes a supporting resistor and a second switch, wherein the supporting resistor and the second switch are connected in series between the first end and the second end of the DC voltage-supporting circuit, and the control terminal of the second switch is electrically connected to the second output terminal of the system controller.

2. A doubly-fed wind turbine control method, applied in the system controller of the doubly-fed wind turbine control system as described in claim 1, characterized in that, The method includes: Monitor the grid connection voltage at the grid connection point and compare the grid connection voltage with a preset grid connection voltage threshold; If the grid connection voltage is greater than or equal to the grid connection voltage threshold, then the voltage-supporting resistor circuit is controlled to be in the conducting state, the DC voltage-supporting circuit is controlled to be in the disconnected state, and the generator-side converter is controlled to send the first direct-axis current and the first quadrature-axis current to the rotor end of the doubly-fed generator. If the grid-connected voltage is less than the grid-connected voltage threshold, the voltage-supporting resistor circuit is controlled to be in the open state, the DC voltage-supporting circuit is controlled to be in the open state, and the generator-side converter is controlled to send a second direct-axis current and a second quadrature-axis current to the rotor end of the doubly-fed generator.

3. The method according to claim 2, characterized in that, The control of the generator-side converter to send a first direct-axis current and a first quadrature-axis current to the rotor end of the doubly-fed generator includes: Monitor the first real-time active power output of the doubly-fed generator, and calculate the first difference between the preset active power reference value and the first real-time active power. The first difference is input into the first proportional-integral controller to obtain the first direct-axis current reference value, and the first direct-axis current reference value is sent to the generator-side converter so that the generator-side converter generates the first direct-axis current according to the first direct-axis current reference value, and sends the first direct-axis current to the rotor end of the doubly-fed generator. Monitor the first real-time excitation voltage output by the doubly-fed generator, and calculate the second difference between the preset grid-connected voltage reference value and the first real-time excitation voltage; The second difference is input into the second proportional-integral controller to obtain the first quadrature-axis current reference value, and the first quadrature-axis current reference value is sent to the generator-side converter so that the generator-side converter generates the first quadrature-axis current according to the first quadrature-axis current reference value, and sends the first quadrature-axis current to the rotor end of the doubly-fed generator.

4. The method according to claim 2, characterized in that, The control of the generator-side converter to send a second direct-axis current and a second quadrature-axis current to the rotor end of the doubly-fed generator includes: Monitor the second real-time active power output of the doubly-fed generator and calculate the third difference between the preset active power protection value and the second real-time active power. The third difference is input into the third proportional-integral controller to obtain the second direct-axis current reference value, and the second direct-axis current reference value is sent to the generator-side converter so that the generator-side converter generates the second direct-axis current according to the second direct-axis current reference value, and sends the second direct-axis current to the rotor end of the doubly-fed generator; Monitor the second real-time excitation voltage output by the doubly-fed generator, and calculate the fourth difference between the preset grid-connected voltage protection value and the second real-time excitation voltage; The fourth difference is input into the fourth proportional-integral controller to obtain the second quadrature-axis current reference value, and the second quadrature-axis current reference value is sent to the generator-side converter so that the generator-side converter generates the second quadrature-axis current according to the second quadrature-axis current reference value, and sends the second quadrature-axis current to the rotor end of the doubly-fed generator.

5. The method according to claim 3, characterized in that, The method further includes: controlling the grid-side converter to generate a third direct-axis current and a third quadrature-axis current, including: Monitor the real-time DC-side voltage of the back-to-back converter and calculate the fifth difference between the preset DC-side voltage reference value and the real-time DC-side voltage; The fifth difference is input into the fifth proportional-integral controller to obtain the third direct-axis current reference value, and the third direct-axis current reference value is sent to the grid-side converter so that the grid-side converter generates the third direct-axis current according to the third direct-axis current reference value. Monitor the real-time reactive power at the grid connection point and calculate the sixth difference between the preset reactive power reference value and the real-time reactive power. The sixth difference is input into the sixth proportional-integral controller to obtain the third quadrature-axis current reference value, and the third quadrature-axis current reference value is sent to the grid-side converter so that the grid-side converter generates the third quadrature-axis current according to the third quadrature-axis current reference value.

6. A doubly-fed fan control device for implementing the method as described in any one of claims 2 to 5, characterized in that, The device includes: The condition judgment module is used to monitor the grid connection voltage of the grid connection point and compare the grid connection voltage with a preset grid connection voltage threshold. The first current generation module is used to control the voltage-supporting resistor circuit to be in the conducting state, control the DC voltage-supporting circuit to be in the disconnected state, and control the generator-side converter to send the first direct-axis current and the first quadrature-axis current to the rotor end of the doubly-fed generator if the grid-connected voltage is greater than or equal to the grid-connected voltage threshold. The second current generation module is used to control the voltage-supporting resistor circuit to be in the open state, control the DC voltage-supporting circuit to be in the open state, and control the generator-side converter to send a second direct-axis current and a second quadrature-axis current to the rotor end of the doubly-fed generator if the grid-connected voltage is less than the grid-connected voltage threshold.

7. A storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 2 to 5.

8. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 2 to 5.

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