Wind turbine pitch control system and wind turbine generator

Abstract

A wind turbine pitch control system (10). The wind turbine pitch control system (10) comprises: a backup pitch control module (100), a switching module (200), and a primary pitch control module (300). When the primary pitch control module (300) fails, the switching module (200) is used for connecting a brake power output end (A1) of the backup pitch control module (100) to a motor side brake end (C1) of the primary pitch control module (300), and the switching module (200) is also used for connecting a motor power output end (A2) of the backup pitch control module (100) to a motor side power end (C2) of the primary pitch control module (300), so that the backup pitch control module (100) drives a motor (320) in the primary pitch control module (300) to control the position of blades. The wind turbine pitch control system (10) can drive the blades to continue grid-connected operation when the primary pitch control module (300) fails, thereby reducing the probability of blade jamming, improving safety performance of wind turbine generators, and further reducing power generation loss of the wind turbine generators. Further comprised is a wind turbine generator.

Description

Technical Field

[0001] The present invention relates to the technical field of wind turbine generation, and in particular to a wind turbine pitch system and a wind turbine generator. Background

[0002] With the gradual maturity of wind turbine technology, offshore high-power units have become a new direction for the development of the wind turbine industry. As a safety component in a wind turbine generator, the pitch system directly affects the input power and safety of the wind turbine generator.

[0003] When the pitch system fails and causes blade jamming, the safety risk of the wind turbine generator may increase. In addition, for offshore wind turbine generators, due to many factors such as harsh offshore environment, limited operation and maintenance time windows, and high offshore operation costs, prolonged shutdown may result in a large amount of power loss. In the current industry, when a pitch system failure causes blade jamming, the blade cannot be feathered back to a safe position, affecting the overall safety of the unit; on the other hand, the pitch system failure prevents the wind turbine generator from continuing grid-connected operation, leading to severe power loss.

[0004] Therefore, how to reduce the probability of blade jamming and power loss is a technical problem to be solved urgently by those skilled in the art. Summary

[0005] The objective of the present invention is to provide a wind turbine pitch system and a wind turbine generator, to improve the safety performance of the wind turbine generator and reduce the power loss thereof.

[0006] To achieve the above objective, technical solutions adopted by the present invention are as follows.

[0007] In an aspect, the present invention provides a wind turbine pitch system, including: a backup pitch module, a switching module, and a main pitch module; a brake power output end of the backup pitch module is disconnected from or connected to a motor-side brake end of the main pitch module through the switching module, and a motor power output end of the backup pitch module is disconnected from or connected to a motor-side power end of the main pitch module through the switching module; when the main pitch module fails, the switching module is configured to connect the brake power output end of the backup pitch module to the motor-side brake end of the main pitch module, and the switching module is further configured to connect the motor power output end of the backup pitch module to the motor-side power end of the main pitch module, so that the backup pitch module drives a motor in the main pitch module to control a position of a blade.

[0008] Further, both the main pitch module and the backup pitch module are connected to a control module; a first port of the switching module is connected to the brake power output end of the backup pitch module, and a second port of the switching module is connected to the motor-side brake end of the main pitch module; a third port of the switching module is connected to the motor power output end of the backup pitch module, and a fourth port of the switching module is connected to the motor-side power end of the main pitch module; when the main pitch module fails, the main pitch module is configured to send a fault signal to the control module, and the control module is configured to, upon receiving the fault signal, send a switching instruction to the backup pitch module; the backup pitch module is configured to, upon receiving the switching instruction, control the first port of the switching module to connect to the second port of the switching module, and control the third port of the switching module to connect to the fourth port of the switching module.

[0009] Further, the switching module includes a brake switching unit and a power switching unit, and the main pitch module includes a first driver and the motor; the first driver is connected to the control module; a first brake power input end of the brake switching unit is connected to a brake power output end of the first driver, a second brake power input end of the brake switching unit is connected to the brake power output end of the backup pitch module, and a brake power output end of the brake switching unit is connected to a brake end of the motor; a first motor power input end of the power switching unit is connected to a motor power output end of the first driver, a second motor power input end of the power switching unit is connected to the motor power output end of the backup pitch module, and a motor power output end of the power switching unit is connected to a power end of the motor; when the first driver fails, the second brake power input end of the brake switching unit is connected to the brake power output end of the brake switching unit, and the second motor power input end of the power switching unit is connected to the motor power output end of the power switching unit.

[0010] Further, the switching module further includes an encoder switching unit, and the main pitch module further includes a first encoder and a second encoder; both the first encoder and the second encoder are disposed on the motor, an output end of the first encoder is connected to an encoder signal input end of the first driver, an output end of the second encoder is connected to an input end of the encoder switching unit, and an output end of the encoder switching unit is connected to an encoder signal input end of the backup pitch module; when the first encoder fails, the input end of the encoder switching unit is connected to the output end of the encoder switching unit.

[0011] Further, the backup pitch module includes a second driver; the second driver is connected to the control module; a brake power output end of the second driver is connected to the second brake power input end of the brake switching unit, a motor power output end of the second driver is connected to the second motor power input end of the power switching unit, and an encoder signal input end of the second driver is connected to the output end of the encoder switching unit.

[0012] Further, the brake switching unit includes a first switch, and a fixed contact of the first switch is connected to the brake end of the motor; when the first driver fails, a movable contact of the first switch is connected to the brake power output end of the backup pitch module.

[0013] Further, the power switching unit includes a second switch, and a fixed contact of the second switch is connected to the power end of the motor; when the first driver fails, a movable contact of the second switch is connected to the power output end of the backup pitch module.

[0014] Further, the encoder switching unit includes a third switch, and a fixed contact of the third switch is connected to the encoder signal input end of the second driver; when the first encoder in the main pitch module fails, the main pitch module in which the first encoder fails is taken as a faulty main pitch module, and a movable contact of the third switch is connected to the output end of the second encoder in the faulty main pitch module.

[0015] Further, the encoder switching unit includes a fourth switch, and a fixed contact of the fourth switch is connected to the output end of the second encoder; when the first encoder in the main pitch module fails, the main pitch module in which the first encoder fails is taken as a faulty main pitch module, and a movable contact of the fourth switch corresponding to the faulty main pitch module is connected to the encoder signal input end of the second driver.

[0016] Further, a power supply end of the first driver and a power supply end of the second driver are both connected to a main power supply.

[0017] Further, the main pitch module further includes a first energy storage device, and the backup pitch module further includes a second energy storage device; the first energy storage device is connected to the first driver, and the second energy storage device is connected to the second driver.

[0018] Further, the first driver internally includes a first charging unit and a first discharging unit, and the second driver internally includes a second charging unit and a second discharging unit; when the main power supply is normal, a direct current bus inside the first driver charges the first energy storage device through the first charging unit, and a direct current bus inside the second driver charges the second energy storage device through the second charging unit; when the main power supply is abnormal, the first energy storage device supplies energy to the direct current bus inside the first driver through the first discharging unit, and the second energy storage device supplies energy to the direct current bus inside the second driver through the second discharging unit.

[0019] Further, the first charging unit and the second charging unit are both BUCK circuits, the first discharging unit and the second discharging unit are both diodes, and the first energy storage device and the second energy storage device are both supercapacitors; when the main power supply is normal, the BUCK circuit provides a constant charging current to the supercapacitor; when the main power supply is abnormal and a direct current bus voltage inside a driver is lower than a voltage of the supercapacitor, the supercapacitor supplies energy to the direct current bus inside the driver through the diode.

[0020] Further, the control module is a PLC controller, and the backup pitch module and the main pitch module are connected to the PLC controller via bus communication.

[0021] In another aspect, the present invention further provides a wind turbine generator, including the wind turbine pitch system according to any one of the above embodiments.

[0022] Compared with the related art, the present invention has following beneficial effects.

[0023] The present invention provides a wind power pitch system and a wind turbine generator, including: a backup pitch module, a switching module and a main pitch module. When the main pitch module fails, the switching module is configured to connect a brake power output end of the backup pitch module to a motor-side brake end of the main pitch module, and the switching module is further configured to connect a motor power output end of the backup pitch module to a motorside power end of the main pitch module. At this time, the backup pitch module can supply brake power and motor power to a motor in the main pitch module that fails, to drive the motor to control a position of a blade, enabling the blade to continue grid-connected operation. This avoids safety risks caused by blade jamming due to failure of the main pitch module, as well as power loss caused by shutdown. Brief Description of Figures

[0024] In order to more clearly illustrate technical solutions of the present invention, the drawings required for use in the present invention will be briefly described below. It should be understood that the following drawings merely illustrate certain technical solutions of the present invention and therefore should not be considered as limiting the scope. For those of ordinary skill in the art, other related drawings may be obtained based on these drawings without any creative effort.

[0025] FIG. 1 is a first structural schematic diagram of a wind turbine pitch system provided by the present invention;

[0026] FIG. 2 is a second structural schematic diagram of a wind turbine pitch system provided by the present invention;

[0027] FIG. 3 is a third structural schematic diagram of a wind turbine pitch system provided by the present invention;

[0028] FIG. 4 is a first principal diagram of a wind turbine pitch system provided by the present invention;

[0029] FIG. 5 is a second principal diagram of a wind turbine pitch system provided by the present invention;

[0030] FIG. 6 is a fourth structural schematic diagram of a wind turbine pitch system provided by the present invention.

[0031] Reference numerals: 10 - wind turbine pitch system; 100 - backup pitch module; 110 -second driver; 120 - second energy storage device; 200 - switching module; 210 - brake switching unit; 220 - power switching unit; 230 - encoder switching unit; 300 - main pitch module; 310 - first driver; 320 - motor; 330 - first encoder; 340 - second encoder; 350 - first energy storage device. Detailed Description

[0032] In order to make objectives, technical solutions, and advantages of the present invention clearer, technical solutions of the present invention will be described clearly and completely below with reference to the accompanying drawings. Obviously, the described technical solutions are part of the technical solutions of the present invention, rather than all of the technical solutions of the present invention. Generally, components of the technical solutions of the present invention described and shown in the accompanying drawings herein may be arranged and designed in various different configurations. Therefore, the following detailed description of the technical solutions of the present invention provided in the accompanying drawings is not intended to limit the scope of the present invention as claimed, but merely represents selected technical solutions of the present invention. Based on the technical solutions of the present invention, all other technical solutions obtained by a person of ordinary skill in the art without making any creative effort shall fall within the protection scope of the present invention.

[0033] As described in the background art, in the current industry, when a pitch system failure causes blade jamming, the blade cannot be feathered back to a safe position, affecting the overall safety of the unit; on the other hand, a pitch system failure prevents the wind turbine from continuing grid-connected operation, leading to severe power loss. Therefore, how to reduce the probability of blade jamming and power loss is a technical problem to be solved urgently by those skilled in the art.

[0034] In order to solve the above technical problem, referring to FIG. 1, the present embodiment provides a wind turbine pitch system 10, including: a backup pitch module 100, a switching module 200, and a main pitch module 300. When the main pitch module 300 is normal, the main pitch module 300 drives the blade.

[0035] A brake power output end A1 of the backup pitch module 100 is disconnected from or connected to a motor-side brake end C1 of the main pitch module 300 through the switching module 200, and a motor power output end A2 of the backup pitch module 100 is disconnected from or connected to a motor-side power end C2 of the main pitch module 300 through the switching module 200.

[0036] When the main pitch module 300 fails, the switching module 200 is configured to connect the brake power output end A1 of the backup pitch module 100 to the motor-side brake end C1 of the main pitch module 300, and the switching module 200 is further configured to connect the motor power output end A2 of the backup pitch module 100 to the motor-side power end C2 of the main pitch module 300.

[0037] At this time, the backup pitch module 100 can provide brake power and motor power to a motor in the main pitch module 300 that fails, to drive the motor to control a position of a blade, avoiding safety risks caused by blade jamming due to failure of the main pitch module 300, as well as power loss caused by shutdown.

[0038] Specifically, in an embodiment of the present invention, both the main pitch module 300 and the backup pitch module 100 are connected to a control module. A first port B1 of the switching module 200 is connected to the brake power output end A1 of the backup pitch module 100, and a second port B2 of the switching module 200 is connected to the motor-side brake end C1 of the main pitch module 300. A third port B3 of the switching module 200 is connected to the motor power output end A2 of the backup pitch module 100, and a fourth port B4 of the switching module 200 is connected to the motor-side power end C2 of the main pitch module 300.

[0039] When the main pitch module 300 fails, the main pitch module 300 sends a fault signal to the control module, and the control module, upon receiving the fault signal, sends a switching instruction to the backup pitch module 100. The backup pitch module 100, upon receiving the switching instruction, controls the first port B1 of the switching module 200 to connect to the second port B2 of the switching module 200, and controls the third port B3 of the switching module 200 to connect to the fourth port B4 of the switching module 200.

[0040] In an optional implementation, referring to FIG. 2, the switching module 200 includes a brake switching unit 210 and a power switching unit 220, and the main pitch module 300 includes a first driver 310 and a motor 320.

[0041] The first driver 310 is connected to the control module. A first brake power input end D1 of the brake switching unit 210 is connected to a brake power output end E1 of the first driver 310, a second brake power input end D2 of the brake switching unit 210 is connected to the brake power output end A1 of the backup pitch module 100, and a brake power output end D3 of the brake switching unit 210 is connected to a brake end G1 of the motor 320.

[0042] A first motor power input end F1 of the power switching unit 220 is connected to a motor power output end E2 of the first driver 310, a second motor power input end F2 of the power switching unit 220 is connected to the motor power output end A2 of the backup pitch module 100, and a motor power output end F3 of the power switching unit 220 is connected to a power end G2 of the motor 320.

[0043] When the first driver 310 in the main pitch module 300 fails, the first driver 310 may be unable to provide brake power and motor power to the motor 320. The first driver 310 sends fault information to the control module, and the control module, upon receiving the fault information, sends a switching instruction to the backup pitch module 100, instructing the backup pitch module 100 to take over the blade corresponding to the first driver 310 that fails.

[0044] At this time, the second brake power input end D2 of the brake switching unit 210 is connected to the brake power output end D3 of the brake switching unit 210, which is equivalent to the backup pitch module 100 providing brake power to the motor 320 in the main pitch module 300 that fails. The second motor power input end F2 of the power switching unit 220 is connected to the motor power output end F3 of the power switching unit 220, which is equivalent to the backup pitch module 100 providing motor power to the motor 320 in the main pitch module 300 that fails. That is, the backup pitch module 100 takes over the first driver 310 that fails and provides brake power and motor power to a corresponding motor 320, so that the motor 320 can normally drive a corresponding blade.

[0045] Further, the switching module 200 further includes an encoder switching unit 230, and the main pitch module 300 further includes a first encoder 330 and a second encoder 340.

[0046] Both the first encoder 330 and the second encoder 340 are disposed on the motor 320. An output end of the first encoder 330 is connected to an encoder signal input end E3 of the first driver 310. An output end of the second encoder 340 is connected to an input end of the encoder switching unit 230, and an output end of the encoder switching unit 230 is connected to an encoder signal input end A3 of the backup pitch module 100.

[0047] In an embodiment of the present invention, the first encoder 330 is a main encoder, and the second encoder 340 is a backup encoder. When the first encoder 330 is normal, position information of the motor 320 is provided by the first encoder 330 to the first driver 310.

[0048] When the first encoder 330 fails, the input end of the encoder switching unit 230 is connected to the output end of the encoder switching unit 230, that is, the position information of the motor 320 is provided by the second encoder 340 to the backup pitch module 100.

[0049] Further, referring to FIG. 3, the backup pitch module 100 includes a second driver 110. The second driver 110 is connected to the control module. A brake power output end A1 of the second driver 110 is connected to the second brake power input end D2 of the brake switching unit 210, a motor power output end A2 of the second driver 110 is connected to the second motor power input end F2 of the power switching unit 220, and an encoder signal input end A3 of the second driver 110 is connected to the output end of the encoder switching unit 230.

[0050] It should be noted that control signals of the brake switching unit 210, the power switching unit 220, and the encoder switching unit 230 all have interlocking logic, to ensure that one blade motor 320 has only one brake power input and one motor power input, and that the encoder signal input end A3 of the second driver 110 has only one encoder signal input.

[0051] In addition, the present invention does not limit the quantity of the main pitch modules 300, that is, the quantity of the main pitch module 300 may be one or more.

[0052] In order to better understand a connection relationship and working principle between the backup pitch module 100 and a plurality of main pitch modules 300, please refer to FIG. 4. Assuming that the wind turbine pitch system 10 includes three main pitch modules 300, the switching module 200 includes three brake switching units 210 and three power switching units 220, and one encoder switching unit 230.

[0053] The control module is a master station, and the second driver and the three first drivers are slave stations. A communication topology between the master station and the slave stations is a daisy-chain form. Optionally, the control module may be a PLC controller, and the PLC controller is connected to the second driver in the backup pitch module and the first drivers in the three main pitch modules via bus communication.

[0054] The brake switching unit 210 includes a first switch, and a fixed contact of the first switch is connected to the brake end of the motor. The power switching unit 220 includes a second switch, and a fixed contact of the second switch is connected to the power end of the motor. The encoder switching unit 230 includes a third switch, and a fixed contact of the third switch is connected to the encoder signal input end of the second driver.

[0055] During normal operation, the control module issues position commands to a first driver A, a first driver B, and a first driver C. A movable contact of the first switch in each brake switching unit 210 is connected to the brake power output end of the corresponding first driver, and a movable contact of the second switch in each power switching unit 220 is connected to the motor power output end of the corresponding first driver. At this time, the first driver in each main pitch module provides brake power and motor power to the corresponding motor, so that the motor drives the blade to operate. The first encoder in each main pitch module feeds back real-time position information of the blade to the corresponding first driver, and the first driver then feeds back the blade position information to the control module, and the control module adjusts the position commands in real time according to the position information of the three blades fed back by the three first drivers.

[0056] When the first encoder A fails, the movable contact of the corresponding first switch K1A is disconnected from the brake power output end of the first driver A, and the movable contact of the corresponding second switch K2A is disconnected from the motor power output end of the first driver A, that is, the first driver A stops motor power output and brake power output. Furthermore, the first driver A feeds back fault information to the control module, and the control module, upon receiving the fault information, sends a switching instruction to the second driver.

[0057] The switching instruction includes number information of the main pitch module that fails and position information of the corresponding blade before the fault. The second driver in the backup pitch module can determine, according to the switching instruction, which specific main pitch module has failed and the position information of the blade driven by the main pitch module that fails, so that the second driver can subsequently take over the first driver in the main pitch module that fails to drive the corresponding motor, ensuring the continuity of blade operation.

[0058] That is, when the first encoder A fails, the second driver, according to the switching instruction sent by the control module, controls the movable contact of the third switch to be connected to the output end A of the second encoder A in the main pitch module that fails, which is equivalent to that the second driver begins to receive the feedback signal of the second encoder A at this time. The movable contact of the corresponding first switch K1A is connected to the brake power output end of the second driver, and the movable contact of the corresponding second switch K2A is connected to the motor power output end of the second driver, which is equivalent to that the second driver replaces the first driver A to drive the motor A, and both the brake power and motor power of the motor A are provided by the second driver.

[0059] Through the above operations, the faulty shaft blade can be restored to normal operation, and the faulty shaft blade is controlled by the second driver to continue running. During regular maintenance, faults of the first driver A and the first encoder A are inspected and addressed. After the faults are addressed, the control module clears latched fault information, so that the first driver A re-drives the corresponding blade.

[0060] Since the quantity of main pitch modules is three, the specific structure of the encoder switching unit 230 may be a single-pole three-throw switch K3 as shown in FIG. 4, or may be three fourth switches K4A, K4B, K4C as shown in FIG. 5.

[0061] Specifically, referring to FIG. 5, the encoder switching unit 230 includes a fourth switch, and a fixed contact of the fourth switch is connected to the output end of the second encoder. Assuming that the quantity of main pitch modules is three, the quantity of fourth switches is also three (i.e., K4A, K4B, K4C), and the fixed contact of each fourth switch is respectively connected to the output end of the corresponding second encoder.

[0062] When the first encoder A in a main pitch module fails, the main pitch module in which the first encoder A fails is taken as a faulty main pitch module. A movable contact of the fourth switch K4A corresponding to the faulty main pitch module is connected to the encoder signal input end of the second driver. At this time, the second driver replaces the first driver A to receive the position information fed back by the second encoder A.

[0063] Further, referring to FIG. 6, a power supply end of the first driver 310 and a power supply end of the second driver 110 are both connected to a main power supply. In order to avoid the problem of blade jamming caused by an abnormality of the main power supply, in an embodiment of the present invention, the main pitch module 300 further includes a first energy storage device 350, and the backup pitch module 100 further includes a second energy storage device 120. The first energy storage device 350 is connected to the first driver 310, and the second energy storage device 120 is connected to the second driver 110.

[0064] In an embodiment of the present invention, the first driver 310 internally includes a first charging unit and a first discharging unit, and the second driver 110 internally includes a second charging unit and a second discharging unit. When the main power supply is normal, a direct current bus inside the first driver 310 charges the first energy storage device 350 through the first charging unit, and a direct current bus inside the second driver 110 charges the second energy storage device 120 through the second charging unit.

[0065] When the main power supply is abnormal, the first energy storage device 350 supplies energy to the direct current bus inside the first driver 310 through the first discharging unit, and the second energy storage device 120 supplies energy to the direct current bus inside the second driver 110 through the second discharging unit. This ensures that each driver has dual power supplies as redundant inputs, and that even in the event of loss of a single power supply, the blade can still be feathered to a safe position, further improving the safety performance of the wind turbine generator.

[0066] Optionally, the first discharging unit and the second discharging unit may be diodes, IGBTs, or MOS transistors, and the first energy storage device 350 and the first energy storage device 350 may be supercapacitors or storage batteries.

[0067] In an embodiment of the present invention, the first charging unit and the second charging unit are both BUCK circuits, the first discharging unit and the second discharging unit are both diodes, and the first energy storage device 350 and the second energy storage device 120 are both supercapacitors.

[0068] When the main power supply is normal, the BUCK circuit provides a constant charging current to the supercapacitor.

[0069] When the main power supply is abnormal and a direct current bus voltage inside a driver is lower than a voltage of the supercapacitor, the supercapacitor supplies energy to the direct current bus inside the driver through the diode.

[0070] Further, the main power supply may be a power grid, and the power grid is connected to a three-phase alternating current input end of the second driver 110 and a three-phase alternating current input end of the first driver 310 respectively. When the power grid experiences an abnormal power failure, the supercapacitor supplies energy to the direct current bus inside the driver through the diode, avoiding shutdown caused by blade jamming.

[0071] In addition, an embodiment of the present invention further provides a wind turbine generator, including the wind turbine pitch system 10 according to any one of the above embodiments.

[0072] In summary, embodiments of the present invention provide a wind turbine pitch system and a wind turbine generator. The wind turbine pitch system includes: a backup pitch module, a switching module, and a main pitch module. A brake power output end of the backup pitch module is disconnected from or connected to a motor-side brake end of the main pitch module through the switching module, and a motor power output end of the backup pitch module is disconnected from or connected to a motor-side power end of the main pitch module through the switching module.

[0073] When the main pitch module fails, the switching module is configured to connect the brake power output end of the backup pitch module to the motor-side brake end of the main pitch module, and the switching module is further configured to connect the motor power output end of the backup pitch module to the motor-side power end of the main pitch module. At this time, the backup pitch module can provide brake power and motor power to the motor in the main pitch module that fails, to drive the motor to control a position of a blade, enabling the blade to continue grid-connected operation. This avoids safety risks caused by blade jamming due to failure of the main pitch module, as well as power loss caused by shutdown.

[0074] In addition, by providing the first energy storage device and the second energy storage device, it is ensured that both the main pitch module and the backup pitch module have dual power supplies as redundant inputs, and that even in the event of loss of the main power supply, the blade can be feathered to a safe position, further improving the safety performance of the wind turbine generator.

[0075] The above descriptions are merely embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc., made within the spirit and principle of the present invention shall fall within the protection scope of the present invention. For those skilled in the art, it is obvious that the present invention is not limited to details of the above exemplary embodiments, and the present invention may be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, embodiments should be regarded as exemplary and non-limiting in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is therefore intended that all changes falling within the meaning and range of equivalents of the claims be encompassed within the present invention. Any reference numerals in the claims shall not be construed as limiting the claim in question.

Claims

1. A wind turbine pitch system, characterized in that, the wind turbine pitch system comprises: a backup pitch module, a switching module, and a main pitch module;a brake power output end of the backup pitch module is disconnected from or connected to a motor-side brake end of the main pitch module through the switching module, and a motor power output end of the backup pitch module is disconnected from or connected to a motor-side power end of the main pitch module through the switching module;when the main pitch module fails, the switching module is configured to connect the brake power output end of the backup pitch module to the motor-side brake end of the main pitch module, and the switching module is further configured to connect the motor power output end of the backup pitch module to the motor-side power end of the main pitch module, so that the backup pitch module drives a motor in the main pitch module to control a position of a blade.

2. The wind turbine pitch system according to claim 1, characterized in that, both the main pitch module and the backup pitch module are connected to a control module;a first port of the switching module is connected to the brake power output end of the backup pitch module, and a second port of the switching module is connected to the motor-side brake end of the main pitch module;a third port of the switching module is connected to the motor power output end of the backup pitch module, and a fourth port of the switching module is connected to the motor-side power end of the main pitch module;when the main pitch module fails, the main pitch module is configured to send a fault signal to the control module, and the control module is configured to, upon receiving the fault signal, send a switching instruction to the backup pitch module; the backup pitch module is configured to, upon receiving the switching instruction, control the first port of the switching module to connect to the second port of the switching module, and control the third port of the switching module to connect to the fourth port of the switching module.

3. The wind turbine pitch system according to claim 2, characterized in that, the switching module comprises a brake switching unit and a power switching unit, and the main pitch module comprises a first driver and the motor;the first driver is connected to the control module; a first brake power input end of the brake switching unit is connected to a brake power output end of the first driver, a second brake power input end of the brake switching unit is connected to the brake power output end of the backup pitchmodule, and a brake power output end of the brake switching unit is connected to a brake end of the motor;a first motor power input end of the power switching unit is connected to a motor power output end of the first driver, a second motor power input end of the power switching unit is connected to the motor power output end of the backup pitch module, and a motor power output end of the power switching unit is connected to a power end of the motor;when the first driver fails, the second brake power input end of the brake switching unit is connected to the brake power output end of the brake switching unit, and the second motor power input end of the power switching unit is connected to the motor power output end of the power switching unit.

4. The wind turbine pitch system according to claim 3, characterized in that, the switching module further comprises an encoder switching unit, and the main pitch module further comprises a first encoder and a second encoder;both the first encoder and the second encoder are disposed on the motor, an output end of the first encoder is connected to an encoder signal input end of the first driver, an output end of the second encoder is connected to an input end of the encoder switching unit, and an output end of the encoder switching unit is connected to an encoder signal input end of the backup pitch module;when the first encoder fails, the input end of the encoder switching unit is connected to the output end of the encoder switching unit.

5. The wind turbine pitch system according to claim 4, characterized in that, the backup pitch module comprises a second driver;the second driver is connected to the control module; a brake power output end of the second driver is connected to the second brake power input end of the brake switching unit, a motor power output end of the second driver is connected to the second motor power input end of the power switching unit, and an encoder signal input end of the second driver is connected to the output end of the encoder switching unit.

6. The wind turbine pitch system according to claim 3, characterized in that, the brake switching unit comprises a first switch, and a fixed contact of the first switch is connected to the brake end of the motor;when the first driver fails, a movable contact of the first switch is connected to the brake power output end of the backup pitch module.

7. The wind turbine pitch system according to claim 3, characterized in that, the power switching unit comprises a second switch, and a fixed contact of the second switch is connected to the power end of the motor;when the first driver fails, a movable contact of the second switch is connected to the power output end of the backup pitch module.

8. The wind turbine pitch system according to claim 5, characterized in that, the encoder switching unit comprises a third switch, and a fixed contact of the third switch is connected to the encoder signal input end of the second driver;when the first encoder in the main pitch module fails, the main pitch module in which the first encoder fails is taken as a faulty main pitch module, and a movable contact of the third switch is connected to the output end of the second encoder in the faulty main pitch module.

9. The wind turbine pitch system according to claim 5, characterized in that, the encoder switching unit comprises a fourth switch, and a fixed contact of the fourth switch is connected to the output end of the second encoder;when the first encoder in the main pitch module fails, the main pitch module in which the first encoder fails is taken as a faulty main pitch module, and a movable contact of the fourth switch corresponding to the faulty main pitch module is connected to the encoder signal input end of the second driver.

10. The wind turbine pitch system according to claim 5, characterized in that, a power supply end of the first driver and a power supply end of the second driver are both connected to a main power supply.

11. The wind turbine pitch system according to claim 10, characterized in that, the main pitch module further comprises a first energy storage device, and the backup pitch module further comprises a second energy storage device; the first energy storage device is connected to the first driver, and the second energy storage device is connected to the second driver.

12. The wind turbine pitch system according to claim 11, characterized in that, the first driver internally comprises a first charging unit and a first discharging unit, and the second driver internally comprises a second charging unit and a second discharging unit;when the main power supply is normal, a direct current bus inside the first driver charges the first energy storage device through the first charging unit, and a direct current bus inside the second driver charges the second energy storage device through the second charging unit;when the main power supply is abnormal, the first energy storage device supplies energy to the direct current bus inside the first driver through the first discharging unit, and the second energy storage device supplies energy to the direct current bus inside the second driver through the second discharging unit.

13. The wind turbine pitch system according to claim 12, characterized in that, the first charging unit and the second charging unit are both BUCK circuits, the first discharging unit and the second discharging unit are both diodes, and the first energy storage device and the second energy storage device are both supercapacitors;when the main power supply is normal, the BUCK circuit provides a constant charging current to the supercapacitor;when the main power supply is abnormal and a direct current bus voltage inside a driver is lower than a voltage of the supercapacitor, the supercapacitor supplies energy to the direct current bus inside the driver through the diode.

14. The wind turbine pitch system according to claim 2, characterized in that, the control module is a PLC controller, and the backup pitch module and the main pitch module are connected to the PLC controller via bus communication.

15. A wind turbine generator, characterized in that, the wind turbine generator comprises the wind turbine pitch system according to any one of claims 1 to 14.

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