A doubly-fed wind turbine generator system, power system and control method

Abstract

This application relates to the field of wind power generation technology, and discloses a doubly-fed induction generator (DFIG) wind turbine generator set, power system, and control method. The generator set includes: a grid-connected transformer; at least two circuit breakers, each connected to the grid-connected transformer; at least two contactors, each connected to a different circuit breaker; at least one grid-side converter, whose AC side is connected to the circuit breakers; a stator, comprising at least two stator windings, each electrically independent and connected to a different contactor; a rotor, comprising a set of rotor windings and at least one rotor slip ring; at least one rotor slip ring is connected to the rotor windings; and at least one generator-side converter, whose AC side is connected to the rotor slip ring, and whose DC side is connected to the DC side of the grid-side converter via a capacitor bus. This reduces the risk of contactor overload operation and circuit breaker malfunction, improving the generator set's operational reliability and power output stability.

Description

Technical Field

[0001] This application relates to the field of wind power generation technology, and in particular to a doubly-fed wind turbine generator set, power system and control method. Background Technology

[0002] Doubly-fed induction generator (DFIG) wind power generation is an important branch of wind power technology, which generates electricity through DFIG wind turbine generator sets. In DFIG wind turbine generator sets, contactors and circuit breakers are also installed between the stator and the transformer to ensure the stable and safe operation of the unit.

[0003] However, contactors are at risk of burning out due to overload operation, and circuit breakers are at risk of tripping erroneously. These risks can further lead to generator shutdowns and power losses, and seriously affect the stability of the power system, ultimately resulting in economic losses. Summary of the Invention

[0004] This application provides a doubly-fed wind turbine generator set, a power system, and a control method, which reduces the risk of contactor overload operation and circuit breaker malfunction in the doubly-fed wind turbine generator set, and provides more than one power transmission channel for the power generated by the generator set. Thus, when some of the power transmission channels fail, other power transmission channels can be switched to continuously transmit power to the grid with zero downtime, thereby improving the operational reliability of the generator set and the power output stability of the power system.

[0005] This application provides a doubly-fed wind turbine generator set, comprising: a grid-connected transformer; at least two circuit breakers, each circuit breaker connected to the grid-connected transformer; at least two contactors, each contactor connected to a different circuit breaker and then connected to the grid-connected transformer; at least one grid-side converter, the AC side of the grid-side converter connected to the circuit breaker and then connected to the grid-connected transformer; a stator, comprising at least two stator windings, each stator winding being electrically independent and each stator winding being connected to a different contactor; a rotor, comprising a set of rotor windings and at least one rotor slip ring; at least one rotor slip ring connected to the rotor windings; at least one turbine-side converter, the AC side of the turbine-side converter connected to the rotor slip ring, and the DC side of the turbine-side converter connected to the DC side of the grid-side converter via a capacitor bus.

[0006] This application also provides a power system including a doubly-fed wind turbine generator set as described in any embodiment of this application.

[0007] This application also provides a control method for zero-downtime switching of a doubly-fed wind turbine generator set as described in any embodiment of this application. The method includes: detecting whether a fault exists in a currently active stator power generation channel, wherein a stator power generation channel is a power transmission channel formed by a stator winding of the generator set and a contactor and a circuit breaker connected in sequence to the stator winding; if a fault exists in at least one currently active stator power generation channel, controlling the contactor in the currently active and faulty stator power generation channel to switch from an active state to an inactive state, and controlling the contactor in at least one currently non-active stator power generation channel to switch from an inactive state to an active state.

[0008] The technical solution provided in this application has at least the following advantages: Each stator winding is electrically independent, and each stator winding is connected to a different contactor. Each circuit breaker is connected to the grid-connected transformer, and each contactor is connected to a different circuit breaker. Therefore, in a doubly-fed wind turbine generator set, each stator winding forms a physically isolated electrical circuit to the grid-connected transformer 100 through the corresponding contactor and circuit breaker. There is no need to shunt current between electrical circuits, which overcomes the influence of the contact resistance between the contactor and the circuit breaker on the magnitude of the current transmitted in the electrical circuit. It avoids the situation of contactor overload operation and circuit breaker false tripping caused by changes in the contact resistance between the contactor and the circuit breaker, reduces the risk of contactor overload operation and circuit breaker false tripping in the doubly-fed wind turbine generator set, and improves the operating reliability of the generator set and the power output stability of the power system. Meanwhile, since the stator contains at least two stator windings, each stator winding is electrically independent and each stator winding is connected to a different contactor, it can be connected to a grid-connected transformer through different circuit breakers connected to the contactors, thereby transmitting the generated electrical energy to the power grid and forming more than one number of electrically independent power transmission channels. In the event of a failure in some of these power transmission channels, the system can switch to other power transmission channels with zero downtime to stably and continuously transmit electrical energy to the power grid, further improving the operational reliability of the generator set and the power output stability of the power system. Attached Figure Description

[0009] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0010] Figure 1 This is a schematic diagram of the structure of a doubly-fed wind turbine generator provided in one embodiment of this application; Figure 2This is a schematic diagram of the structure of a doubly-fed wind turbine generator provided in another embodiment of this application; Figure 3 This is a schematic diagram of the structure of a doubly-fed wind turbine generator provided in another embodiment of this application; Figure 4 This is a schematic diagram of the structure of a doubly-fed wind turbine generator provided in another embodiment of this application; Figure 5 This is a schematic diagram of the structure of a doubly-fed wind turbine generator provided in another embodiment of this application; Figure 6 This is a schematic diagram of the structure of a doubly-fed wind turbine generator provided in another embodiment of this application; Figure 7 This is a schematic diagram of the structure of a doubly-fed wind turbine generator provided in another embodiment of this application; Figure 8 This is a schematic diagram of the structure of a doubly-fed wind turbine generator provided in another embodiment of this application; Figure 9 This is a schematic diagram of the structure of a doubly-fed wind turbine generator provided in another embodiment of this application; Figure 10 This is a schematic diagram of the structure of a doubly-fed wind turbine generator provided in another embodiment of this application; Figure 11 This is a schematic diagram of the structure of a doubly-fed wind turbine generator provided in another embodiment of this application; Figure 12 This is a schematic diagram of the structure of a doubly-fed wind turbine generator provided in another embodiment of this application; Figure 13 This is a schematic diagram of the structure of a doubly-fed wind turbine generator provided in another embodiment of this application; Figure 14 This is a schematic diagram of the structure of a doubly-fed wind turbine generator provided in another embodiment of this application; Figure 15 This is a schematic diagram of the structure of a doubly-fed wind turbine generator provided in another embodiment of this application; Figure 16 This is a schematic diagram of the structure of a doubly-fed wind turbine generator provided in another embodiment of this application; Figure 17 This is a schematic diagram of the structure of a doubly-fed wind turbine generator provided in another embodiment of this application; Figure 18 This is a schematic diagram of the structure of a doubly-fed wind turbine generator provided in another embodiment of this application; Figure 19 This is a schematic diagram of the structure of a doubly-fed wind turbine generator provided in another embodiment of this application; Figure 20This is a schematic diagram of the structure of a doubly-fed wind turbine generator provided in another embodiment of this application; Figure 21 This is a cross-sectional view of the stator and rotor structure in a doubly-fed wind turbine generator provided in another embodiment of this application; Figure 22 yes Figure 21 A partial sectional view of the stator and rotor structure in a doubly-fed wind turbine generator set provided in the image; Figure 23 This is a schematic diagram of the power system provided in another embodiment of this application; Figure 24 This is a flowchart of a control method provided in another embodiment of this application; Figure 25 This is a flowchart of a control method provided in another embodiment of this application; Figure 26 This is a flowchart of a control method provided in another embodiment of this application; Figure 27 This is a flowchart of a control method provided in another embodiment of this application; Figure 28 This is a flowchart of a control method provided in another embodiment of this application; Figure 29 This is a flowchart of a control method provided in another embodiment of this application. Detailed Implementation

[0011] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the various embodiments of this application will be described in detail below with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been presented in the various embodiments of this application to enable readers to better understand this application. However, the technical solutions claimed in this application can be implemented even without these technical details and various changes and modifications based on the following embodiments.

[0012] The division of the following embodiments is for ease of description and should not constitute any limitation on the specific implementation of this application. The various embodiments can be combined with and referenced by each other without contradiction.

[0013] like Figure 1 As shown, a doubly-fed wind turbine generator set mainly includes: a wind turbine generator, a converter, and a grid-connected transformer. The generator stator is directly connected to the grid-connected transformer, while the generator rotor is connected to the grid-connected transformer via the converter. Thus, the generator can transmit the electrical energy converted from wind energy to the power grid through the stator, rotor, and grid-connected transformer.

[0014] Furthermore, to ensure safer and more reliable control of the electrical circuit's on / off state, circuit breakers and contactors are installed in doubly-fed wind turbine generator sets. The contactors safely extract the electrical energy generated on the stator, while the circuit breakers control the on / off state of the electrical circuit. However, due to capacity limitations of circuit breakers and contactors, exceeding these limits can lead to contactor overload and circuit breaker malfunctions, causing generator shutdown, power loss, and severely impacting power system stability, ultimately resulting in economic losses. To prevent contactor overload and circuit breaker malfunctions, and to ensure stable and safe power transmission, circuit breakers and contactors in the electrical circuits of doubly-fed wind turbine generator sets are further configured with... Figure 2 The arrangement shown forms multiple parallel electrical circuits, allowing the stator output current to be shunted between different electrical circuits according to the contact resistance between the circuit breakers and contactors contained in each electrical circuit, and transmitted to the grid-connected transformer through each electrical circuit in a manner not exceeding the capacity limits of the circuit breakers and contactors in that electrical circuit.

[0015] However, over time, especially in highly corrosive environments (such as offshore and coastal areas), the contact resistance between circuit breakers and contactors can easily change. This causes variations in the current distribution ratio of a single stator output across different electrical circuits, resulting in changes in the magnitude of the current transmitted on each circuit. For example, the current that was originally evenly distributed across different electrical circuits becomes uneven, and no other electrical circuit can share the current. Some electrical circuits can only transmit currents exceeding the capacity limits of the circuit breakers and contactors. This leads to circuit breaker tripping, contactor overload and burnout, wind turbine shutdowns, and power losses, severely impacting the stability of the power system and ultimately resulting in economic losses.

[0016] Furthermore, the stator structure in generators typically features a single stator winding. While multi-stator winding structures are also supported, current focus on the specific arrangement of the stator windings rather than the electrical circuit configuration for safely and reliably supplying power to the grid. In particular, issues such as circuit breaker tripping and contactor burnout due to overload still exist. For example, patent CN110149037A provides a dual-stator, dual-salient-stage high-power generator, primarily focusing on wind energy utilization and structural compactness. It achieves high power output through coordinated control of internal and external generators, suitable for off-grid / grid-connected wind power to hydrogen production. Similarly, patent CN110971095A provides a dual-stator, dual-rotor wind turbine, primarily focusing on structural compactness and power generation. It improves the low-voltage ride-through capability of the power generation system and simplifies the wind power control system by combining a permanent magnet synchronous generator and a doubly-fed generator.

[0017] Therefore, in order to solve the problems of circuit breaker false tripping and contactor overload operation caused by changes in the contact resistance between the circuit breaker and the contactor, and to provide a safe and reliable electrical circuit for multi-stator generators to safely and reliably deliver electrical energy to the power grid, this application provides a doubly-fed wind turbine generator set. While setting multiple stator windings in the generator set, each stator winding forms a physically isolated electrical circuit consisting of a stator winding, a contactor, a circuit breaker, and a grid-connected transformer. This avoids current shunting between electrical circuits, overcomes the influence of the contact resistance between the contactor and the circuit breaker on the magnitude of the current transmitted in the electrical circuit, and avoids contactor overload operation and circuit breaker false tripping caused by changes in the contact resistance between the contactor and the circuit breaker. This reduces the risk of contactor overload operation and circuit breaker false tripping in the doubly-fed wind turbine generator set, and improves the operational reliability of the generator set and the power output stability of the power system. Meanwhile, since the stator contains at least two stator windings, each electrically independent and connected to different contactors, it can be connected to a grid-connected transformer via different circuit breakers connected to the contactors. This allows the generated electricity to be transmitted to the power grid, forming more than one electrically independent power transmission channel. Therefore, if some of these channels fail, the system can switch to other channels with zero downtime to stably and continuously transmit electricity to the grid, further improving the operational reliability of the generator set and the power output stability of the power system. The following will describe the doubly-fed wind turbine generator set provided in this application embodiment with reference to different embodiments.

[0018] In some embodiments, such as Figures 3-20 As shown, a doubly-fed wind turbine generator set includes: Grid-connected transformer 100; At least two circuit breakers 200, each of which is connected to the grid-connected transformer 100; At least two contactors 300, each contactor 300 is connected to a different circuit breaker 200 and then connected to a grid-connected transformer 100; At least one grid-side converter 400, whose AC side is connected to the circuit breaker 200 and then connected to the grid-connected transformer 100; The stator 500 includes at least two stator windings 501, each stator winding 501 being electrically independent and each stator winding 501 being connected to a different contactor 300. Rotor 600 includes a set of rotor windings 601 and at least one rotor slip ring 602; at least one rotor slip ring 602 is connected to the rotor windings. At least one machine-side converter 700, the AC side of which is connected to the rotor slip ring 602, and the DC side of which is connected to the DC side of the grid-side converter 400 via a capacitor bus 800.

[0019] For ease of understanding, the various structures provided in the above embodiments will be described below.

[0020] The grid-connected transformer 100 is used to connect to the power grid. It can be any transformer that can convert the voltage of the received electrical energy into the voltage required by the power grid, so as to convert the electrical signal transmitted from the stator winding 501 through the corresponding contactor 300 and circuit breaker 200 into an electrical signal that meets the power transmission requirements and send it into the power grid.

[0021] The circuit breaker 200 can be any circuit breaker capable of closing, carrying, and interrupting current under normal or abnormal circuit conditions to control the grid connection operation of the generator set. Thus, when the electrical circuit is operating normally, it maintains the electrical circuit's continuity, transmitting the electrical signal output from the stator winding 501 of the electrical circuit to the grid-connected transformer 100; when an abnormality occurs in the electrical circuit (such as abnormal current), it disconnects the electrical circuit, preventing the abnormal electrical signal from being transmitted to the grid-connected transformer 100 and affecting the normal operation of other electrical circuits of the generator set. Ultimately, this ensures the safety and stability of the grid connection process.

[0022] It should be noted that the embodiments of this application do not limit the on / off control method of the circuit breaker 200. For example, the circuit breaker 200 may have integrated data acquisition, data processing and control functions, and control the circuit to remain on or off by acquiring the currently transmitted electrical signal and determining whether the electrical circuit is working properly; or, the circuit breaker 200 may receive external control signals and respond to the external control signals to remain on or off, etc., which will not be listed here.

[0023] It should also be noted that the embodiments of this application do not limit the connection method between the circuit breaker 200 and the grid-connected transformer 100. In some cases, the grid-connected transformer 100 may include at least one low-voltage winding, and the circuit breaker 200 is connected to the grid-connected transformer 100 by connecting to the low-voltage winding, etc.

[0024] Contactor 300 can be any contactor capable of controlling the connection and disconnection between the electrical energy output from stator winding 501 and circuit breaker 200. This ensures the safety and stability of the transmission of electrical signals from stator winding 501 to the corresponding electrical circuit.

[0025] For grid-side converter 400, it can be any converter that can have DC to AC conversion function (i.e., DC / AC converter).

[0026] For stator 500, it can be any stator with two or more electrically isolated stator windings.

[0027] It should be noted that the embodiments of this application do not limit the implementation method of achieving electrical independence between different stator windings 501. For example, in some embodiments, such as Figure 21 and Figure 22 As shown, multiple sets of independent three-phase winding systems without electrical connections can be formed by multiple sets of three-phase stator winding leads, thus achieving physical isolation and electrical independence. Several rotor slip rings are sleeved on a central shaft, and a rotor is sleeved on the outside of the shaft. Several independent rotor windings are arranged on the surface of the rotor away from the shaft. Multiple sets of rotor winding leads are connected to multiple sets of rotor slip rings to provide three-phase current output (U1-V1-W1, U2-V2-W2 shown in the figure). At this time, multiple machine-side frequency converters are connected through multiple sets of slip rings, covering each stator winding 501, causing each stator winding 501 to generate an induced current through electromagnetic induction, thereby providing three-phase current output through three adjacent stator windings (A1-B1-C1, A2-B2-C2 shown in the figure).

[0028] certainly, Figure 21 and Figure 22 This is just one example; in some cases, at least two stator windings 501 can be configured in other ways, which will not be listed here.

[0029] For rotor 600, this application embodiment provides a set of rotor windings, that is, the generator is driven by a common rotor.

[0030] It should be noted that the number of rotor slip rings 602 is not limited in this application embodiment, and can be set according to requirements.

[0031] The generator-side converter 700 can be any converter capable of AC-to-DC conversion (i.e., an AC / DC converter). In this case, the generator-side converter 700, connected to the rotor slip ring 602, excites the rotor 600, controls the magnetic field formed by the rotor 600, and thus controls the phase, frequency, amplitude, etc. of the voltage output by the stator 500 to be consistent with the grid. Furthermore, the generator-side converter 700, in cooperation with the grid-side converter 400, can also control the generator to achieve soft grid connection, reducing the adverse effects of grid connection inrush current on the generator and the grid.

[0032] For capacitor bus 800, it can be any DC capacitor bus.

[0033] It should be noted that, as Figure 3 , Figure 15As shown, in an example where the number of generator-side converters 700 can be one and the number of grid-side converters 400 is one, the configuration of converters in the generator set can be simplified to the greatest extent, saving hardware resources and reducing costs. In some embodiments, such as... Figure 4 , Figure 5 , Figures 8-14 , Figure 16 , Figures 18-20 As shown, the number of machine-side converters 700 can be greater than or equal to 2; in some embodiments, such as Figures 6-14 , Figures 17-20 As shown, the number of grid-side converters 400 can also be greater than or equal to 2. The following mainly explains the cases where the number of generator-side converters 700 is greater than or equal to 2, and / or the number of grid-side converters 400 is greater than or equal to 2.

[0034] In some embodiments, such as Figure 4 , Figure 5 , Figures 8-14 , Figure 16 , Figures 18-20 As shown, the number of machine-side converters 700 is greater than or equal to two, and the number of rotor slip rings 602 is greater than or equal to the number of machine-side converters 700. Each machine-side converter 700 has a different rotor slip ring 602 connected to its AC side, and each machine-side converter 700 has its DC side connected to the corresponding grid-side converter 400 via a capacitor bus 800. This arrangement of multiple machine-side converters 700 and multiple rotor slip rings 602 allows for the shunting of the current generated on the rotor 600, significantly reducing the operating current of each rotor slip ring 602 and machine-side converter 700. This effectively solves overheating and reliability issues, and ultimately resolves the problem of insufficient current carrying capacity of a single slip ring.

[0035] In some embodiments, such as Figure 5 , Figures 8-14 , Figure 16 , Figures 18-20 As shown, the generator set also includes at least one switch 900, and the AC side of at least one generator-side converter 700 is connected to the corresponding rotor slip ring 602 via the switch 900. This allows the switch 900 to control the rotor slip ring channel formed between the rotor slip ring 602 and the grid-connected voltage transformer 100, switching between on and off states. Furthermore, when a fault occurs in one of the rotor slip ring channels, the generator set can switch to other rotor slip ring channels with zero downtime to stably and continuously transmit power between the rotor slip ring 602 and the grid-connected voltage transformer 100, further improving the operational reliability of the generator set and the power output stability of the power system. The switch 900 can be any contactor.

[0036] It should be noted that the switch 900 in this embodiment can be implemented by any switch, such as a contactor, circuit breaker or remote control switch, etc., which will not be listed here.

[0037] In some embodiments, such as Figure 5 , Figures 8-14 , Figure 16 , Figures 18-20 As shown, the number of switches 900 is equal to the number of rotor slip rings 602. The AC side of each machine-side converter 700 is connected to the corresponding rotor slip ring 602 through different switches 900. In this way, zero-downtime switching of the rotor slip ring channel can be supported to the greatest extent, which can further improve the reliability and stability of power transmission between the rotor slip ring 602 and the grid-connected voltage transformer 100.

[0038] In some embodiments, such as Figures 6-14 , Figures 17-20 As shown, the number of grid-side converters 400 is greater than or equal to 2. The DC side of each grid-side converter 400 is connected to the DC side of the corresponding machine-side converter 700 through the capacitor bus 800. The AC side of each grid-side converter 400 is connected to the grid-connected transformer 100 through the circuit breaker 200.

[0039] In some embodiments, such as Figure 6 As shown, the AC sides of at least two grid-side converters 400 are connected to the grid-connected transformer 100 through the same circuit breaker 200. This allows the same circuit breaker 200 to be reused to control the on / off state of the electrical circuits of two or more grid-side converters 400, making full use of the on / off control function of the circuit breaker 200, saving hardware resources and reducing costs.

[0040] In some embodiments, such as Figures 7-14 , Figures 17-20 As shown, the AC sides of at least two grid-side converters 400 are connected to the grid-connected transformer 100 via different circuit breakers 200. This allows for the shunting of electrical energy output from the rotor 600, while simultaneously transmitting the shunted energy to the grid-connected transformer 100 through at least partially physically isolated electrical circuits. This further reduces the risk of exceeding the capacity limit of the circuit breaker 200 due to overcurrent, and further improves the operational reliability of the generator set and the power output stability of the power system.

[0041] In some embodiments, such as Figures 8-14 , Figures 18-20As shown, the number of generator-side converters 700 is greater than or equal to 2, and the number of grid-side converters 400 is greater than or equal to 2. This allows for the splitting of electrical energy output from the rotor 600 in both generator-side and grid-side dimensions. Furthermore, it enables more flexible and variable physical isolation of the electrical circuit between the rotor slip ring 602 and the grid-connected transformer 100 for power transmission. This further avoids abnormal operation or even shutdown of the unit caused by failures of some generator-side converters 700 and / or grid-side converters 400, further improving the operational reliability of the generator set and the power output stability of the power system.

[0042] It should be noted that the embodiments of this application do not limit the connection relationship between the machine-side converter 700 and the grid-side converter 400 formed by the capacitor bus 800.

[0043] In some embodiments, such as Figures 8-10 , Figures 12-14 , Figures 18-20 As shown, at least two generator-side converters 700 are connected to different grid-side converters 400 via different capacitor buses 800. This enables the formation of multiple electrically independent power transmission channels between the generator side and the grid side. Even if some generator-side converters 700 malfunction, normal power transmission can still be maintained on the rotor slip ring channel through the operating generator-side converters 700, further improving the reliability and stability of power transmission between the rotor slip ring 602 and the grid-connected voltage transformer 100.

[0044] In some embodiments, such as Figure 9 , Figure 10 , Figures 12-14 , Figures 18-20 As shown, at least two grid-side converters 400 are connected to different machine-side converters 700 via different capacitor buses 800. This enables the formation of multiple electrically independent power transmission channels between the machine side and the grid side. Even if some grid-side converters 400 malfunction, normal power transmission can still be maintained on the rotor slip ring channel through the normally operating grid-side converters 400, further improving the reliability and stability of power transmission between the rotor slip ring 602 and the grid-connected voltage transformer 100.

[0045] In some embodiments, such as Figure 10As shown, the number of machine-side converters 700 is equal to the number of grid-side converters 400, and each grid-side converter 400 is connected to a different machine-side converter 700 through a different capacitor bus 800. This allows for the formation of multiple electrically independent power transmission channels between the machine side and the grid side to the greatest extent possible. Even if some grid-side converters 400 and / or some grid-side converters 400 malfunction, normal power transmission can still be maintained in the rotor slip ring channel through the normally operating machine-side converters 700 and grid-side converters 400, further improving the reliability and stability of power transmission between the rotor slip ring 602 and the grid-connected voltage transformer 100.

[0046] Of course, the fact that the number of machine-side converters 700 is equal to the number of grid-side converters 400 is only one example. In some embodiments, such as... Figure 12 , Figure 13 As shown, the number of machine-side converters 700 and the number of grid-side converters 400 can be different.

[0047] In some embodiments, such as Figure 11 As shown, all machine-side converters 700 and all grid-side converters 400 are connected through the same capacitor bus 800. This allows for maximum reuse of the same capacitor bus 800, maintaining power transmission between the machine-side converters 700 and the grid-side converters 400, saving hardware resources and reducing costs.

[0048] In some embodiments, such as Figure 12 , Figure 14 As shown, at least two machine-side converters 700 are connected to the same grid-side converter 400 via the same capacitor bus 800. Therefore, even if some machine-side converters 700 fail, normal power transmission can still be maintained through the operating machine-side converters 700 on the rotor slip ring channel, further improving the reliability and stability of power transmission between the rotor slip ring 602 and the grid-connected voltage transformer 100.

[0049] In some embodiments, such as Figure 6 , Figure 7 , Figure 9 , Figure 11 , Figure 13 , Figure 14 , Figure 17 , Figure 19 , Figure 20 As shown, at least two grid-side converters 400 are connected to the same generator-side converter 700 via the same capacitor bus 800. Therefore, even if some grid-side converters 400 fail, normal power transmission can still be maintained through the operating grid-side converters 400 on the rotor slip ring channel, further improving the reliability and stability of power transmission between the rotor slip ring 602 and the grid-connected voltage transformer 100.

[0050] It should be noted that when at least two grid-side converters 400 are connected to the same generator-side converter 700 via the same capacitor bus 800, current shunting will occur between the at least two grid-side converters 400 connected to the same generator-side converter 700 via the same capacitor bus 800. This application does not limit the current distribution ratio. The current can be shunted among n (n≥2) grid-side converters 400 according to any ratio that satisfies: P1, P2...Px...Pn are all greater than or equal to 0, and P1(%)+...Px(%)+...Pn(%)=100%. Among them, P1, P2...Px...Pn can be equal (in this case, the current is evenly distributed among the n grid-side converters 400) or unequal.

[0051] As can be seen from the above embodiments, this application supports the flexible establishment of a connection between the grid-side converter 400 and the machine-side converter 700 through the capacitor bus 800, making the deployment of doubly-fed wind turbine generator sets more flexible.

[0052] In some embodiments, such as Figures 3-14 As shown, at least one grid-side converter 400 is connected to the grid-connected transformer 100 via a circuit breaker 200 connected to a contactor 300. This further reduces the risk of overcurrent exceeding the capacity limit of the circuit breaker 200, further improving the operational reliability of the generator set and the power output stability of the power system. Furthermore, it allows reuse of the circuit breaker 200 connected to the stator winding 501 to control the on / off state of the electrical circuit containing the grid-side converter 400, fully utilizing the on / off control function of the circuit breaker 200, saving hardware resources and reducing costs.

[0053] In some embodiments, such as Figures 15-20 As shown, at least one grid-side converter 400 is connected to the grid-connected transformer 100 via a circuit breaker 200 not connected to the contactor 300. This further reduces the risk of the overcurrent exceeding the capacity limit of the circuit breaker 200, further improving the operational reliability of the generator set and the power output stability of the power system. It also enables physical isolation between the electrical circuit containing the stator winding 501 and the electrical circuit containing the grid-side converter 400, achieving more precise on / off control of the electrical circuit while increasing electrical circuit safety and power generation. In particular, as... Figure 16As shown, when all generator-side converters 700 are connected to the same grid-side converter 400 via the same capacitor bus 800, the currents of the generator-side converters 700 are combined at the grid-side converter 400. At this time, the current of the grid-side converter 400 may be too large. In this case, by setting an independent circuit breaker 200 for the grid-side converter 400, the combined current of the generator-side converters 700 can be independently connected to the grid-connected transformer 100, which can effectively reduce the risk of the current exceeding the carrying capacity of the circuit breaker 200.

[0054] It should also be noted that in some embodiments, some grid-side converters 400 and contactors 300 may share the same circuit breaker 200, and some grid-side converters 400 and contactors 300 may use completely different circuit breakers 200, which will not be elaborated here.

[0055] Furthermore, it is not difficult to find Figures 15-20 The accompanying drawings are largely the same as those of the aforementioned embodiments, with the main difference being whether the grid-side converter 400 and the contactor 300 share the circuit breaker 200 or not. This will not be discussed further here. Figures 15-20 I will go into detail about each one.

[0056] Through the above Figures 3-20 As shown in the doubly-fed wind turbine generator set, the embodiment of this application features a structure with multiple electrically independent stator windings. Each stator winding is equipped with an independent circuit breaker and contactor, enabling each stator winding to transmit electrical energy to the grid-connected transformer via physically isolated electrical circuits (i.e., power generation channels). After conversion by the grid-connected transformer to meet transmission requirements, the energy is fed into the power grid. In other words, an independent power generation system is formed based on each stator winding, resulting in: performance improvements, zero-downtime switching under partial electrical circuit failure conditions through redundant design of multiple power generation channels, significantly improving power supply continuity; efficiency improvements, higher power output through multiple stator windings, achieving superior power generation efficiency; and cost improvements, extended maintenance cycles, reduced maintenance requirements, and significantly lower costs.

[0057] Furthermore, to highlight the innovative aspects of this application, this embodiment does not introduce units that are not closely related to solving the technical problem proposed in this application. However, this does not mean that other units are absent from this embodiment. Adding insignificant modifications or introducing insignificant designs to the unit structure, without altering its core structural design, are all within the scope of protection of this patent.

[0058] The second aspect of this application also provides a power system, such as... Figure 23 As shown, the power system includes: A plurality of wind turbine generator sets 1, wherein at least one wind turbine generator set 1 is a doubly fed wind turbine generator set as described in any of the above embodiments. Several grid-connected transformers 2, each grid-connected transformer 2 is connected to different wind turbine generator sets 1 respectively; Several high-voltage switchgear 3, each high-voltage switchgear is connected to a different grid-connected transformer; The power grid 4 is connected to each high-voltage switchgear 3 respectively.

[0059] It is not difficult to see that this embodiment is a system embodiment corresponding to the unit embodiment, and this embodiment can be implemented in conjunction with the unit embodiment. The relevant technical details mentioned in the unit embodiment are still valid in this embodiment, and will not be repeated here to reduce repetition. Accordingly, the relevant technical details mentioned in this embodiment can also be applied to the unit embodiment.

[0060] Furthermore, in order to highlight the innovative aspects of this application, no units that are not closely related to solving the technical problems proposed in this application are introduced in this embodiment, but this does not mean that there are no other units in this embodiment.

[0061] The third aspect of this application also provides a control method, which can be executed by a controller, control device, or control equipment installed inside the unit, or by a controller, control device, or control equipment installed outside the unit, to perform zero-downtime switching of the doubly-fed wind turbine generator set as described in any of the above embodiments. The following will be combined with... Figures 24-29 The flowchart shown illustrates the control method provided in the embodiments of this application.

[0062] In some embodiments, the flow of the control method is as follows: Figure 24 As shown, it includes: Step S11: Detect whether there is a fault in the currently connected stator power generation channel. Here, a stator power generation channel is a power transmission channel formed by a stator winding in the unit and a contactor and a circuit breaker connected in sequence to the stator winding.

[0063] Step S12: If at least one of the currently active stator power generation channels is faulty, control the currently active and faulty stator power generation channel to switch from the active state to the disconnected state, and distribute the power carried by the stator power generation channel switched to the disconnected state to the other stator power generation channels.

[0064] exist Figure 23In the illustrated embodiment, since the stator includes at least two stator windings, each stator winding is electrically independent and connected to different contactors, it can be connected to a grid-connected transformer via different circuit breakers connected to the contactors, thereby transmitting the generated electrical energy to the power grid and forming more than one number of electrically independent power transmission channels. Therefore, if a fault is detected in at least one currently active stator power generation channel, the fault can be removed from the currently used electrical circuit by controlling the contactor in the currently active and faulty stator power generation channel to switch from the active state to the open state. Simultaneously, the power carried by the stator power generation channel switched to the open state can be redistributed to other stator power generation channels, i.e., power redistribution, maintaining a constant power generation output and further improving the operational reliability of the generator set and the power output stability of the power system.

[0065] For ease of understanding Figure 24 The steps of the illustrated embodiment will be explained below.

[0066] In step S11, this embodiment of the application does not limit the method of fault detection. It can detect whether a fault has occurred by collecting electrical signals on the stator power generation channel and detecting whether a fault has occurred based on the collected electrical signals. It can also detect whether a fault has occurred by collecting information on the working environment and working status of related structures (such as contactors) in the stator power generation channel and detecting whether a fault has occurred based on the collected information. Among them, when detecting whether a fault has occurred based on the collected electrical signals or information, fault detection can be achieved by judging whether the collected electrical signals or information (or the data calculated based on the collected electrical signals or information) are within a preset range. Alternatively, the collected electrical signals or information (or the data calculated based on the collected electrical signals or information) can be used as input to an artificial intelligence model to achieve fault detection.

[0067] In step S12, the control of the contactor being turned on or off can be achieved by sending control signals, etc.

[0068] It should be noted that the embodiments of this application do not limit the number of contactors that need to switch from the off state to the on state. The number is related to the rated power of each stator power generation channel and the desired operating state. Assuming that the rated power of each stator power generation channel is the same, in some embodiments, an equal number of contactors can be selected to switch from the on state to the off state, thereby reducing the number of contactors in operation, lowering power consumption, and ensuring more idle contactors are available during the next fault detection, better supporting zero-downtime switching. Alternatively, more contactors can be selected than the number switching from the on state to the off state, thereby reducing the risk of the stator power generation channel exceeding its capacity.

[0069] It should be noted that this application does not limit the redistribution method of the power carried by the stator power generation channel switched to the off state. In some embodiments, the power carried by the stator power generation channel switched to the off state can be distributed to other stator power generation channels in the following ways: controlling the stator winding connected to the stator power generation channel that is currently in the conducting state to operate at rated power; and / or controlling the contactor in at least one stator power generation channel that is currently not in the conducting state to switch from the off state to the conducting state.

[0070] In some cases, to fully utilize the carrying capacity of the currently active stator power generation channel, reduce the number of contactor control operations, and lower the risk of errors, the carrying capacity of the currently active stator power generation channel can be used first. Only when the power required to switch to the deactivated stator power generation channel cannot be met should another active stator power generation channel be selected. In other words, allocating the power required to switch to the deactivated stator power generation channel to other stator power generation channels can be achieved as follows: control the stator winding connected to the currently active stator power generation channel to operate at its rated power; if the additional power generated by the stator winding connected to the currently active stator power generation channel operating at its rated power is less than the power required to switch to the deactivated stator power generation channel, then continuously control the contactor in at least one currently deactivated stator power generation channel to switch from the deactivated to the active state until the additional power is greater than or equal to the power required to switch to the deactivated stator power generation channel.

[0071] Of course, the above are just examples. In some embodiments, it is also possible to prioritize controlling the contactor in at least one currently non-conducting stator power generation channel to switch from the open state to the on state, etc., which will not be elaborated here.

[0072] In some embodiments, the flow of the control method is as follows: Figure 25 As shown, it includes: Step S21: Detect whether there is a fault in the currently conducting stator power generation channel. Here, a stator power generation channel is a power transmission channel formed by a stator winding in the unit and a contactor and a circuit breaker sequentially connected to the stator winding. If so, execute Step S22; if not, execute Step S21.

[0073] Step S22: Control the currently conducting and faulty stator power generation channel to switch from the conducting state to the disconnected state, and allocate the power carried by the stator power generation channel switched to the disconnected state to other stator power generation channels.

[0074] Step S23: Detect whether the sum of the rated powers of the currently conducting stator power generation channels is less than the expected power generation. If so, execute Step S24; if not, execute Step S23.

[0075] Step S24: Determine the first number of stator power generation channels to be conducted according to the expected power generation, the number of currently conducting stator power generation channels, and the rated power of a single stator power generation channel, and control the contactors in the first number of currently non-conducting and non-faulty stator power generation channels to switch from the disconnected state to the conducting state.

[0076] That is to say, on the basis of the Figure 24 shown embodiment, redundant detection of the unit power generation is further introduced. When there is redundancy, by increasing the conducting stator power generation channels, the power generation of the unit can be fully utilized, the resource utilization rate can be improved, resource waste can be reduced, and the economy of the unit can be improved.

[0077] Among them, Figure 25 Steps 21 to 22 shown are substantially the same as Steps S11 to S12 of the foregoing embodiment, and will not be elaborated here one by one.

[0078] In Step S23, the present application does not limit the implementation manner of detecting whether the sum of the rated powers of the currently conducting stator power generation channels is less than the expected power generation. For example, in some embodiments, detecting whether the sum of the rated powers of the currently conducting stator power generation channels is less than the expected power generation is realized by detecting whether the following expression is satisfied: X1×Pe < Pt, where X1 is the number of currently conducting stator power generation channels, Pe is the rated power of a single stator power generation channel, Pt is the expected power generation, and X1 is a positive integer.

[0079] In Step S24, the present application does not determine the specific value of the first number. It can be any number that can ensure that after controlling the contactors in the second number of currently conducting stator power generation channels to switch from the conducting state to the disconnected state, the rated power of the conducting stator power generation channels is not less than the power generation of the unit.

[0080] In some embodiments, in order to reduce unnecessary waste, the first number of stator power generation channels to be turned on is determined by the following expression: (X1 + X2 - 1) × Pe < Pt ≤ (X1 + X2) × Pe; where X1 is the number of currently turned-on stator power generation channels, Pe is the rated power of a single stator power generation channel, Pt is the desired power generation, X2 is the first number, and both X1 and X2 are positive integers.

[0081] In Figure 25 the illustrated embodiment, by actively increasing the turned-on stator power generation channels (i.e., cut-in channels) under overload conditions, it is ensured that the currently turned-on stator power generation channels never exceed the rated value, enabling rapid fault removal and real-time load redistribution during the operation of the unit, thereby improving the safety and reliability of the system.

[0082] In some embodiments, the flow of the control method is as Figure 26 illustrated and includes: Step S31, detecting whether there is a fault in the currently turned-on stator power generation channels, where a stator power generation channel is a power transmission channel formed by a stator winding in the unit and a contactor and a circuit breaker sequentially connected to the stator winding. If so, execute step S32; if not, execute step S31.

[0083] Step S32, controlling the currently turned-on and faulty stator power generation channels to switch from the turned-on state to the off state, and distributing the power carried by the stator power generation channels switched to the off state to other stator power generation channels.

[0084] Step S33, detecting whether the power margin of the currently turned-on stator power generation channels is greater than the rated power of a single stator power generation channel. If so, execute step S34; if not, execute step S33.

[0085] Step S34, determining the second number of stator power generation channels to be turned off according to the desired power generation, the number of currently turned-on stator power generation channels, and the rated power of a single stator power generation channel, and controlling the contactors in the second number of currently turned-on stator power generation channels to switch from the turned-on state to the off state.

[0086] That is to say, on the basis of the Figure 24 illustrated embodiment, redundant detection of the currently turned-on stator power generation channels is further introduced. When there is redundancy, by reducing the turned-on stator power generation channels, unnecessary operation of the stator power generation channels is avoided, resource waste is reduced, the loss of the stator power generation channels is reduced, and the available duration of the entire unit is extended.

[0087] Where Figure 26Steps 31 to 32 shown are substantially the same as steps S11 to S12 in the foregoing embodiments, and thus will not be elaborated herein.

[0088] In step S33, in the present application, the power margin of the currently conducting stator power generation channel refers to the difference between the total power of the currently conducting stator power generation channel when operating at the rated power and the expected power generation power.

[0089] Based on this, in some embodiments, it is detected whether the power margin of the currently conducting stator power generation channel is greater than the rated power of a single stator power generation channel, which is achieved by detecting whether the following expression is satisfied: (X1 - 1) × Pe > Pt, where X1 is the number of currently conducting stator power generation channels, Pe is the rated power of a single stator power generation channel, Pt is the expected power generation power, and X1 is a positive integer.

[0090] In step S34, the present application does not determine the specific value of the second quantity, which can be any quantity that enables the rated power of the conducting stator power generation channels to be not less than the power generation power of the unit after the contactors in the second quantity of currently conducting stator power generation channels are switched from the conducting state to the off state.

[0091] In some embodiments, in order to reduce unnecessary waste, the second quantity of the stator power generation channels to be disconnected is determined by solving the following expression: (X1 - X3 - 1) × Pe < Pt ≤ (X1 - X3) × Pe; where X1 is the number of currently conducting stator power generation channels, Pe is the rated power of a single stator power generation channel, Pt is the expected power generation power, X3 is the second quantity, and X1 and X3 are both positive integers.

[0092] In Figure 26 In the shown embodiments, by actively reducing the conducting stator power generation channels (i.e., cutting out channels) under low load or partial redundancy, the long-term operating stress of each structure in the stator power generation channels is reduced, and at the same time, sufficient standby capacity is retained, significantly improving the reliability and service life of the system.

[0093] It should be noted that the present application does not limit the acquisition methods of the expected power generation power, the number of currently conducting stator power generation channels, and the rated power of the stator power generation channels. In some embodiments, the expected power generation power can be obtained from the power generation plan, the number of currently conducting stator power generation channels is obtained by recording the state control of the stator power generation channels after the unit starts, and the rated power of a single stator power generation channel can be read from the product manuals of contactors and the like in the stator power generation channels or obtained through experiments.

[0094] It should also be noted that Figure 25 the shown embodiments and Figure 26The steps in the illustrated embodiments can be combined with each other. For example, steps S23 and S3 can be executed simultaneously, etc., which will not be listed one by one here.

[0095] Similarly, when the unit also includes switches, and different generator-side converters are connected to different rotor slip rings through different switches, the rotor slip ring channel can be controlled in a manner similar to that of the stator generator channel. The rotor slip ring channel is a power transmission channel formed by a rotor slip ring in the unit and a switch, generator-side converter, grid-side converter and contactor connected to the rotor slip ring in sequence.

[0096] Therefore, in some embodiments, the flow of the control method may further include Figure 27 The steps shown are as follows: Step S41: Detect whether there is a fault in the currently connected rotor slip ring channel. Here, a rotor slip ring channel is a power transmission channel formed by a rotor slip ring in the unit and a switch, a machine-side converter, a grid-side converter and a circuit breaker connected in sequence to the rotor slip ring.

[0097] Step S42: If at least one of the currently conducting rotor slip ring channels is faulty, control the switch in the currently conducting rotor slip ring channel with the fault to switch from the conducting state to the disconnected state, and distribute the power carried by the rotor slip ring channel switched to the disconnected state to other stator power generation channels.

[0098] In some embodiments, the power carried by a rotor slip ring channel switched to the off state is allocated to other stator power generation channels by controlling the rotor slip ring connected to the rotor slip ring channel currently in the on state to operate at rated power; and / or controlling a switch in at least one rotor slip ring channel that is currently not in the on state to switch from the off state to the on state.

[0099] In some embodiments, the flow of the control method may further include Figure 28 The steps shown are as follows: Step S51: Detect whether there is a fault in the currently active rotor slip ring channel. A rotor slip ring channel is a power transmission channel formed by a rotor slip ring in the unit and a switch, a machine-side converter, a grid-side converter, and a circuit breaker connected sequentially to the rotor slip ring. If yes, proceed to step S52; otherwise, proceed to step S51.

[0100] Step S52: Control the switch in the currently conducting rotor slip ring channel with a fault to switch from the conducting state to the disconnected state, and distribute the power carried by the rotor slip ring channel switched to the disconnected state to other stator power generation channels.

[0101] Step S53: Check if the sum of the rated currents of the currently conducting rotor slip ring channels is less than the expected current. If yes, proceed to step S54; otherwise, proceed to step S53.

[0102] Step S54: Based on the desired current, the number of currently conducting rotor slip ring channels, and the rated current of a single rotor slip ring channel, determine the third number of rotor slip ring channels to be conducted, and control the switches in the third number of currently non-conducting and fault-free rotor slip ring channels to switch from the open state to the on state.

[0103] In some embodiments, detecting whether the sum of the rated currents of the currently conducting rotor slip ring channels is less than the desired current can be achieved by detecting whether the following expression is satisfied: Y1×Ie <It。

[0104] In some embodiments, the third number of rotor slip ring channels to be activated is determined by solving the following expression: (Y1+Y2-1)×Ie <It≤(Y1+Y2)×Ie。

[0105] Where Y1 is the number of currently active rotor slip ring channels, Ie is the rated current of a single rotor slip ring channel, It is the desired current, Y2 is the third quantity, and Y1 and Y2 are both positive integers.

[0106] In some embodiments, the flow of the control method may further include Figure 29 The steps shown are as follows: Step S61: Detect whether there is a fault in the currently active rotor slip ring channel. A rotor slip ring channel is a power transmission channel formed by a rotor slip ring in the unit and a switch, a machine-side converter, a grid-side converter, and a circuit breaker connected sequentially to the rotor slip ring. If yes, proceed to step S62; otherwise, proceed to step S61.

[0107] Step S62: Control the switch in the currently conducting rotor slip ring channel with a fault to switch from the conducting state to the disconnected state, and distribute the power carried by the rotor slip ring channel switched to the disconnected state to other stator power generation channels.

[0108] Step S63: Detect whether the current margin of the currently conducting rotor slip ring channel is greater than the rated current of a single rotor slip ring channel. If yes, proceed to step S64; otherwise, proceed to step S63.

[0109] Step S64: Based on the desired current, the number of currently conducting rotor slip ring channels, and the rated current of a single rotor slip ring channel, determine the fourth number of rotor slip ring channels to be disconnected, and control the switches in the fourth number of currently conducting rotor slip ring channels to switch from the conducting state to the disconnected state.

[0110] In this application, the current margin of the currently conducting rotor slip ring channel refers to the difference between the total current of the currently conducting rotor slip ring channel and the expected current when the currently conducting rotor slip ring channel is operating at the rated current.

[0111] Based on this, in some embodiments, detecting whether the current margin of the currently conducting rotor slip ring channel is greater than the rated current of a single rotor slip ring channel can be achieved by detecting whether the following expression is satisfied: (Y1-1)×Ie>It; In some embodiments, the fourth number of rotor slip ring channels to be disconnected is determined by solving the following expression: (Y1-Y3-1)×Ie <It≤(Y1-Y3)×Ie; Where Y1 is the number of currently active rotor slip ring channels, Ie is the rated current of a single rotor slip ring channel, It is the desired current, Y3 is the fourth quantity, and Y1 and Y3 are both positive integers.

[0112] It is not hard to see that Figures 27-29 The illustrated embodiment is similar to... Figures 24-26 The embodiments shown are largely the same, with the main differences being that they target different channels, and the objects being switched and the specific information used in the calculations are different. Therefore, the similarities will not be elaborated here.

[0113] Furthermore, the above embodiments primarily control the conduction or disconnection of the stator power generation channel from the perspective of controlling the contactor, and the conduction or disconnection of the rotor slip ring channel from the perspective of controlling the switch. However, as described in the aforementioned unit embodiments, circuit breakers also affect the conduction or disconnection of the stator power generation channel and the rotor slip ring channel. Therefore, circuit breakers can also be controlled when necessary. For example, when it is necessary to reduce the number of conducting stator power generation channels, the circuit breaker in the stator power generation channel that needs to be disconnected can be set to the open state (if it does not affect the state of other channels), etc. Of course, all circuit breakers can also be kept conducting, thus eliminating the need to adjust the state of the circuit breakers, etc., which will not be elaborated further here.

[0114] Those skilled in the art will understand that the above embodiments are specific embodiments for implementing this application, and in practical applications, various changes can be made to them in form and detail without departing from the spirit and scope of this application.

Claims

1. A doubly-fed wind turbine generator set, characterized in that, include: Grid-connected transformer; At least two circuit breakers, each of which is connected to the grid-connected transformer; At least two contactors, each of which is connected to a different circuit breaker and then connected to the grid-connected transformer; At least one grid-side converter, wherein the AC side of the grid-side converter is connected to the circuit breaker and then connected to the grid-connected transformer; The stator includes at least two stator windings, each stator winding being electrically independent and each stator winding being connected to a different contactor. A rotor comprising a set of rotor windings and at least one rotor slip ring; at least one of the rotor slip rings is connected to the rotor windings; At least one machine-side converter, wherein the AC side of the machine-side converter is connected to the rotor slip ring, and the DC side of the machine-side converter is connected to the DC side of the grid-side converter via a capacitor bus.

2. The doubly-fed wind turbine generator set according to claim 1, characterized in that, The number of machine-side converters is 1, and / or the number of grid-side converters is 1.

3. The doubly-fed wind turbine generator set according to claim 1, characterized in that, The number of machine-side converters is greater than or equal to 2, the number of rotor slip rings is greater than or equal to the number of machine-side converters, each machine-side converter has a different rotor slip ring connected to its AC side, and each machine-side converter has its DC side connected to the corresponding grid-side converter via a capacitor bus.

4. The doubly-fed wind turbine generator set according to claim 3, characterized in that, The unit also includes at least one switch, and the AC side of at least one of the generator-side converters is connected to the corresponding rotor slip ring through the switch.

5. The doubly-fed wind turbine generator set according to claim 4, characterized in that, The number of switches is equal to the number of rotor slip rings, and the AC side of each machine-side converter is connected to the corresponding rotor slip ring through different switches.

6. The doubly-fed wind turbine generator set according to claim 1, characterized in that, The number of grid-side converters is greater than or equal to 2. The DC side of each grid-side converter is connected to the DC side of the corresponding generator-side converter through a capacitor bus. The AC side of each grid-side converter is connected to the grid-connected transformer through the circuit breaker.

7. The doubly-fed wind turbine generator set according to claim 6, characterized in that, At least two of the grid-side converters are connected to the grid-connected transformer via different circuit breakers on their AC sides.

8. The doubly-fed wind turbine generator set according to claim 6, characterized in that, At least two of the grid-side converters are connected to the grid-connected transformer via the same circuit breaker on their AC sides.

9. The doubly-fed wind turbine generator set according to claim 1, characterized in that, The number of machine-side converters is greater than or equal to 2, and the number of grid-side converters is greater than or equal to 2.

10. The doubly-fed wind turbine generator set according to claim 9, characterized in that, At least two of the machine-side converters are connected to different grid-side converters via different capacitor buses.

11. The doubly-fed wind turbine generator set according to claim 9, characterized in that, At least two of the grid-side converters are connected to different machine-side converters via different capacitor buses.

12. The doubly-fed wind turbine generator set according to any one of claims 9 to 11, characterized in that, The number of machine-side converters is equal to the number of grid-side converters, and each grid-side converter is connected to a different machine-side converter through a different capacitor bus.

13. The doubly-fed wind turbine generator set according to any one of claims 3 to 9, characterized in that, All the machine-side converters and all the grid-side converters are connected through the same capacitor bus.

14. The doubly-fed wind turbine generator set according to any one of claims 3 to 11, characterized in that, At least two of the machine-side converters are connected to the same grid-side converter via the same capacitor bus.

15. The doubly-fed wind turbine generator set according to any one of claims 3 to 11, characterized in that, At least two of the grid-side converters are connected to the same machine-side converter via the same capacitor bus.

16. The doubly-fed wind turbine generator set according to any one of claims 1 to 11, characterized in that, At least one of the grid-side converters is connected to the grid-connected transformer via the circuit breaker connected to the contactor.

17. The doubly-fed wind turbine generator set according to any one of claims 1 to 11, characterized in that, At least one of the grid-side converters is connected to the grid-connected transformer via the circuit breaker that is not connected to the contactor.

18. The doubly-fed wind turbine generator set according to any one of claims 1 to 11, characterized in that, The number of machine-side converters is different from the number of grid-side converters.

19. An electric power system, characterized in that, include: A plurality of wind turbine generator sets, wherein the plurality of wind turbine generator sets include at least one doubly fed wind turbine generator set as claimed in any one of claims 1 to 18; Several grid-connected transformers, each of which is connected to a different wind turbine generator set; Several high-voltage switchgear, each of which is connected to a different grid-connected transformer; The power grid is connected to each of the aforementioned high-voltage switchgear.

20. A control method, characterized in that, The method for zero-downtime switching of a doubly-fed wind turbine generator set as described in any one of claims 1 to 18 includes: Detect whether there is a fault in the currently connected stator power generation channel, wherein one of the stator power generation channels is a power transmission channel formed by a stator winding in the unit and a contactor and a circuit breaker connected in sequence to the stator winding; If at least one of the currently active stator power generation channels is faulty, the currently active and faulty stator power generation channel is switched from an active state to an inactive state, and the power carried by the stator power generation channel switched to the inactive state is distributed to the other stator power generation channels.

21. The control method according to claim 20, characterized in that, The step of allocating the power carried by the stator power generation channel that has been switched to the disconnected state to the other stator power generation channels includes: Control the stator windings connected to the stator power generation channel, which are currently in a conducting state, to operate at rated power; And / or, Control the contactor in at least one of the currently non-conducting stator power generation channels to switch from an open state to a closed state.

22. The control method according to claim 20 or 21, characterized in that, The method further includes: The system detects whether the sum of the rated power of the currently active stator power generation channels is less than the expected power generation. If it is less than the expected power generation, the system determines a first number of stator power generation channels to be activated based on the expected power generation, the number of currently active stator power generation channels, and the rated power of a single stator power generation channel. The system then controls the contactors in the first number of currently non-active and non-faulty stator power generation channels to switch from an open state to an active state. And / or, The system detects whether the power margin of the currently active stator power generation channel is greater than the rated power of a single stator power generation channel. If it is greater than the rated power of a single stator power generation channel, the system determines a second number of stator power generation channels to be disconnected based on the desired power generation, the number of currently active stator power generation channels, and the rated power of a single stator power generation channel. The system then controls the contactors in the second number of currently active stator power generation channels to switch from the active state to the disconnected state.

23. The control method according to claim 22, characterized in that, The detection of whether the sum of the rated power of the currently active stator power generation channels is less than the expected power generation is achieved by detecting whether the following expression is satisfied: X1×Pe <Pt; And / or, The determination of the first number of stator power generation channels to be activated is achieved by the following expression: (X1+X2-1)×Pe <Pt≤(X1+X2)×Pe; And / or, The detection of whether the power margin of the currently active stator power generation channel is greater than the rated power of a single stator power generation channel is achieved by detecting whether the following expression is satisfied: (X1-1)×Pe>Pt; And / or, The determination of the second number of stator power generation channels to be disconnected is achieved by solving the following expression: (X1-X3-1)×Pe <Pt≤(X1-X3)×Pe; Wherein, X1 is the number of stator power generation channels currently in operation, Pe is the rated power of a single stator power generation channel, Pt is the desired power generation, X2 is the first quantity, X3 is the second quantity, and X1, X2 and X3 are all positive integers.

24. The control method according to claim 20 or 21, characterized in that, The unit also includes a switch, and in the unit, different generator-side converters are connected to different rotor slip rings through different switches; The method further includes: Detect whether there is a fault in the currently connected rotor slip ring channel, wherein one rotor slip ring channel is a rotor slip ring in the unit and a power transmission channel formed by a switch, the machine-side converter, the grid-side converter and the circuit breaker connected in sequence to the rotor slip ring; If at least one of the currently active rotor slip ring channels is faulty, the switch in the currently active and faulty rotor slip ring channel is controlled to switch from the active state to the inactive state, and the power carried by the rotor slip ring channel switched to the inactive state is allocated to the other stator power generation channels.

25. The control method according to claim 24, characterized in that, The process of allocating the power carried by the rotor slip ring channel, which is switched to the disconnected state, to the other stator power generation channels includes: The rotor slip ring connected to the rotor slip ring channel, which is currently in a conducting state, is controlled to operate at rated power; And / or, Control the switch in at least one of the rotor slip ring channels that is currently not conducting to switch from an off state to an on state.

26. The control method according to claim 24, characterized in that, The method further includes: The sum of the rated currents of the currently conducting rotor slip ring channels is detected to be less than the expected current. If it is less than the expected current, a third number of rotor slip ring channels to be conducted is determined based on the expected current, the number of currently conducting rotor slip ring channels, and the rated current of a single rotor slip ring channel. The switches in the third number of currently non-conducting and non-faulty rotor slip ring channels are controlled to switch from the off state to the on state. And / or, The system detects whether the current margin of the currently conducting rotor slip ring channel is greater than the rated current of a single rotor slip ring channel. If it is greater than the rated power of a single rotor slip ring channel, it determines a fourth number of rotor slip ring channels to be disconnected based on the desired current, the number of currently conducting rotor slip ring channels, and the rated current of a single rotor slip ring channel. The system then controls the switches in the fourth number of currently conducting rotor slip ring channels to switch from the conducting state to the disconnected state.

27. The control method according to claim 26, characterized in that, The detection of whether the sum of the rated currents of the currently conducting rotor slip ring channels is less than the expected current is achieved by detecting whether the following expression is satisfied: Y1×Ie <It; And / or, The determination of the third number of rotor slip ring channels to be activated is achieved by solving the following expression: (Y1+Y2-1)×Ie <It≤(Y1+Y2)×Ie; The detection of whether the current margin of the currently conducting rotor slip ring channel is greater than the rated current of a single rotor slip ring channel is achieved by detecting whether the following expression is satisfied: (Y1-1)×Ie>It; And / or, The determination of the fourth number of rotor slip ring channels to be disconnected is achieved by solving the following expression: (Y1-Y3-1)×Ie <It≤(Y1-Y3)×Ie; Wherein, Y1 is the number of rotor slip ring channels currently in operation, Ie is the rated current of a single rotor slip ring channel, It is the desired current, Y2 is the third quantity, Y3 is the fourth quantity, and Y1, Y2 and Y3 are all positive integers.

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