A backup power supply charging circuit and control method for a wind turbine pitch control system

Abstract

The present invention discloses a backup power supply charging circuit for a variable pitch system of a wind turbine and a control method thereof. The charging circuit comprises a charger power supply, a backup power supply, n chargers, and n control modules. The charger power supply, each charger, and the backup power supply are electrically connected in sequence to form a branch circuit. Each charger is electrically connected to a control module, and the n control modules are interconnected; wherein n is a positive integer and n≥2. The present invention solves the problems of long charging time and high probability of charging failure in the prior art.

Description

Technical Field

[0001] The invention relates to the technical field of wind power generation pitch control, and in particular to a backup power supply charging circuit for a wind turbine pitch control system and a control method thereof. Background Art

[0002] The pitch control system is one of the core control systems of the wind turbine. It has functions such as adjusting the input power of the wind rotor and pneumatic brakes, which directly affects the performance and safety of the wind turbine. When the power supply of the power grid is normal, the pitch control system draws power from the power grid to adjust the pitch; when the power grid fails, the pitch control system draws power from the backup power supply to drive the blades back to the storm position to achieve safe shutdown.

[0003] The backup power supply of the pitch system provides energy to ensure that the system can drive the blades back to a safe position in the event of a power grid failure. With the current trend of large-scale wind turbines, especially offshore turbines, the power level of the turbines has increased, the weight and length of the supporting blades have continued to increase, and the pitch load has also increased. Therefore, a lot of energy is required to drive the motor to adjust the blades to safely retract the blades, so the backup power supply capacity must be increased.

[0004] For wind turbines with ultra-large power ratings, especially offshore wind turbines, the traditional single-pitch motor-driven pitch system can no longer meet the requirements of driving the blades to adjust the pitch angle. An electric pitch system is required that uses two or more pitch motors to jointly drive the blades for pitch adjustment.

[0005] The existing backup power supply has only one charger for charging. When the capacity of the backup power supply increases, the charging time becomes longer. In addition, due to the increase in the capacity of the backup power supply and the influence of the operating environment of the wind turbine, the probability of failure in the backup power supply charging is getting higher and higher. The existing technology does not solve the problems of long charging time and high probability of charging failure. Summary of the invention

[0006] In order to overcome the deficiencies of the prior art, the present invention provides a backup power supply charging circuit for a wind turbine pitch control system and a control method thereof, which solve the problems of long charging time and high probability of charging failure in the prior art.

[0007] The technical solution adopted by the present invention to solve the above problems is:

[0008] A backup power charging circuit for a wind turbine pitch control system comprises a charger power supply, a backup power supply, n chargers, and n control modules. The charger power supply, each charger, and the backup power supply are electrically connected in sequence to form a branch circuit. Each charger is electrically connected to a control module, and the n control modules are interconnected. Wherein, n is a positive integer and n≥2.

[0009] The n charging branches of the present invention charge the backup power supply together; when the backup power supply capacity of the variable pitch system is greatly increased, the charging time is shortened, so that the variable pitch system can quickly enter a ready state; at the same time, safety redundancy is achieved, and when a charger fails, another charger can still charge the backup power supply, and the variable pitch system can continue to operate, avoiding the loss of power generation due to unit shutdown, thereby improving the reliability of the dual-drive variable pitch system and even the wind turbine.

[0010] As a preferred technical solution, it also includes a voltage measurement module electrically connected to the backup power supply, and the voltage measurement module is also electrically connected to the n control modules respectively.

[0011] The voltage measurement module measures the backup power supply voltage value and feeds it back to the control module. The control module controls the charging mode and start and stop of the charger according to the preset charging control strategy based on the backup power supply voltage value.

[0012] As a preferred technical solution, it also includes n unidirectional conductive elements, and the charger power supply, each charger, each unidirectional conductive element, and the backup power supply are electrically connected in sequence to form a branch.

[0013] The unidirectional conductive element ensures that the charging current can only flow in one direction from the charger to the backup power supply, thereby preventing the current of the backup power supply from flowing back to the charger and improving the reliability and safety of the circuit.

[0014] As a preferred technical solution, the unidirectional conductive element is a diode.

[0015] The diode has good unidirectional conductivity, strong versatility, small size and easy maintenance.

[0016] As a preferred technical solution, n=2, the two chargers are respectively a master charger and a slave charger, and the two control modules are respectively a master control module and a slave control module.

[0017] The two charging branches charge the backup power supply together; when the backup power supply capacity of the dual-drive variable pitch system is greatly increased, the charging time is shortened, and the variable pitch system quickly enters the ready state; at the same time, safety redundancy is achieved. When the main charger fails, the slave charger can still charge the backup power supply, and the variable pitch system can continue to operate, avoiding the loss of power generation due to unit shutdown, and improving the reliability of the dual-drive variable pitch system and even the wind turbine. It is worth noting that the two charging branches are interchangeable, and the master and slave can be exchanged.

[0018] A control method for a backup power supply charging circuit of a wind turbine pitch control system. When a main charger is in a fault state, a main control module and a slave control module are switched with each other, and a main charger and a slave charger are switched with each other.

[0019] When the main charger is in a faulty state, the master and slave charging circuits switch with each other to achieve safety redundancy. When the main charger fails, the slave charger can still charge the backup power supply and the pitch system can continue to operate, avoiding the loss of power generation due to unit shutdown and improving the reliability of the dual-drive pitch system and even the wind turbine.

[0020] As a preferred technical solution, when the main charger and the slave charger are in normal state, when the backup power supply voltage is lower than a% of the preset voltage value, the main charger and the slave charger charge the backup power supply with a constant current; wherein 50≤a≤95.

[0021] This makes it easy to increase the backup power supply charging input current, shorten the backup power supply charging time, improve the charging efficiency, and enable the backup power supply to enter a ready state as quickly as possible.

[0022] As a preferred technical solution, when the main charger and the slave charger are in normal state, when the backup power supply voltage is greater than a% of the preset voltage value and lower than 100%, the slave control module shuts off the output of the slave charger and only charges the backup power supply with a constant current through the main charger.

[0023] This makes it easier to maintain the backup power supply charging input current stable, achieve a smooth transition from constant current charging mode to constant voltage charging mode, and avoid charger or backup power supply failure caused by charging current output mismatch when two chargers switch from constant current charging mode to constant voltage charging mode at the same time.

[0024] As a preferred technical solution, when the main charger and the slave charger are both in normal state, when the backup power supply voltage reaches the preset voltage value for the first time, the output of the slave charger is shut down by the control module, and the backup power supply is charged at a constant voltage only by the main charger, so as to keep the backup power supply voltage stable within the range of b% to 100% of the preset value; wherein, 90≤b<100 and a<b.

[0025] This makes it easier to maintain the backup power supply voltage stable, ensuring that in the event of a power outage, the backup power supply is fully charged and stores enough energy to drive the variable pitch motor to drive the blades to achieve safe propeller alignment, thereby ensuring the safety of the unit.

[0026] As a preferred technical solution, a is set to 90 and b is set to 99.

[0027] As a preferred technical solution, when one of the main charger and the slave charger fails, when the backup power supply voltage is lower than 100% of the preset voltage value, the faulty charger shuts off the output by itself or through the connected control module, and only the normal charger charges the backup power supply with a constant current.

[0028] This makes it easy to charge the backup power supply at the fastest speed in the event of a charger failure, allowing the backup power supply to be ready as soon as possible, avoiding shutdown due to failure, reducing the charging failure rate, and the pitch control system only issues a single charger failure alarm, thereby improving the reliability of the pitch control system.

[0029] As a preferred technical solution, when one of the main charger and the slave charger fails, when the backup power supply voltage reaches the preset voltage value for the first time, the faulty charger shuts off the output by itself or through the connected control module, and only the normal charger charges the backup power supply at a constant voltage, keeping the backup power supply voltage stable within the range of b% to 100% of the preset value.

[0030] This makes it convenient for the backup power supply to be fully charged in the event of a charger failure or a grid power outage, storing enough energy to drive the pitch motor to drive the blades to achieve safe pitch alignment, ensuring the safety of the unit, avoiding failure shutdowns, and reducing the charging failure rate. The pitch system only issues a single charger failure alarm, improving the reliability of the pitch system.

[0031] As a preferred technical solution, it is characterized in that b is set to 99.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] (1) The n charging branches of the present invention charge the backup power supply together; when the backup power supply capacity of the variable pitch system is greatly increased, the charging time is shortened, so that the variable pitch system can quickly enter the ready state; at the same time, safety redundancy is achieved. When a charger fails, another charger can still charge the backup power supply, and the variable pitch system can continue to operate, avoiding the loss of power generation due to unit shutdown, thereby improving the reliability of the dual-drive variable pitch system and even the wind turbine;

[0034] (2) The present invention measures the backup power supply voltage value through the voltage measurement module and feeds back to the control module. The control module controls the charging mode and start and stop of the charger according to the backup power supply voltage value and a preset charging control strategy;

[0035] (3) The unidirectional conductive element of the present invention ensures that the charging current can only flow in one direction from the charger to the backup power supply, thereby preventing the current of the backup power supply from flowing back to the charger, thereby improving the reliability and safety of the circuit;

[0036] (4) The diode of the present invention has good unidirectional conductivity, strong versatility, small size and easy maintenance;

[0037] (5) In the present invention, when the main charger is in a faulty state, the main and slave charging circuits switch with each other to achieve safety redundancy. When the main charger fails, the slave charger can still charge the backup power supply, and the pitch control system can continue to operate, avoiding the loss of power generation due to unit shutdown, thereby improving the reliability of the dual-drive pitch control system and even the wind turbine.

[0038] (6) The present invention facilitates increasing the backup power supply charging input current, shortening the backup power supply charging time, improving the charging efficiency, and enabling the backup power supply to enter a ready state as quickly as possible;

[0039] (7) The present invention facilitates maintaining the stability of the backup power supply charging input current, realizes a smooth transition from the constant current charging mode to the constant voltage charging mode, and avoids the failure of the charger or the backup power supply caused by the mismatch of charging current output when two chargers are switched from the constant current charging mode to the constant voltage charging mode at the same time;

[0040] (8) The present invention facilitates maintaining the voltage stability of the backup power supply, ensuring that in the event of a power outage, the backup power supply is fully charged and stores sufficient energy to drive the variable pitch motor to drive the blades to achieve safe propeller feathering, thereby ensuring the safety of the unit;

[0041] (9) The present invention facilitates charging the backup power supply at the fastest speed when one charger fails, so that the backup power supply enters the ready state as soon as possible, avoids shutdown due to failure, reduces the charging failure rate, and the pitch control system only issues a single charger failure alarm, thereby improving the reliability of the pitch control system;

[0042] (10) The present invention facilitates that when one of the chargers fails and a power outage occurs in the grid, the backup power supply is in a fully charged state and stores sufficient energy to drive the pitch motor to drive the blades to achieve safe pitch alignment, thereby ensuring the safety of the unit, avoiding shutdown due to failures, and reducing the charging failure rate. The pitch system only issues a single charger failure alarm, thereby improving the reliability of the pitch system. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a structural schematic diagram of the backup power supply charging circuit of the present invention;

[0044] Figure 2 This is a schematic diagram of the charging control strategy when both chargers are in a normal state in Embodiment 3 of the present invention;

[0045] Figure 3 This is a schematic diagram of the charging control strategy when only one charger is in a normal state in Embodiment 3 of the present invention. DETAILED DESCRIPTION

[0046] The present invention will be further described in detail below in conjunction with embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0047] Example 1

[0048] like Figures 1 to 3 As shown, a backup power charging circuit for a wind turbine pitch control system includes a charger power supply, a backup power supply, n chargers, and n control modules. The charger power supply, each charger, and the backup power supply are electrically connected in sequence to form a branch, each charger is electrically connected to a control module, and the n control modules are interconnected; wherein n is a positive integer and n≥2.

[0049] The n charging branches of the present invention charge the backup power supply together; when the backup power supply capacity of the variable pitch system is greatly increased, the charging time is shortened, so that the variable pitch system can quickly enter a ready state; at the same time, safety redundancy is achieved, and when a charger fails, another charger can still charge the backup power supply, and the variable pitch system can continue to operate, avoiding the loss of power generation due to unit shutdown, thereby improving the reliability of the dual-drive variable pitch system and even the wind turbine.

[0050] As a preferred technical solution, it also includes a voltage measurement module electrically connected to the backup power supply, and the voltage measurement module is also electrically connected to the n control modules respectively.

[0051] The voltage measurement module measures the backup power supply voltage value and feeds it back to the control module. The control module controls the charging mode and start and stop of the charger according to the preset charging control strategy based on the backup power supply voltage value.

[0052] As a preferred technical solution, it also includes n unidirectional conductive elements, and the charger power supply, each charger, each unidirectional conductive element, and the backup power supply are electrically connected in sequence to form a branch.

[0053] The unidirectional conductive element ensures that the charging current can only flow in one direction from the charger to the backup power supply, thereby preventing the current of the backup power supply from flowing back to the charger and improving the reliability and safety of the circuit.

[0054] As a preferred technical solution, the unidirectional conductive element is a diode.

[0055] The diode has good unidirectional conductivity, strong versatility, small size and easy maintenance.

[0056] As a preferred technical solution, n=2, the two chargers are respectively a master charger and a slave charger, and the two control modules are respectively a master control module and a slave control module.

[0057] The two charging branches charge the backup power supply together; when the backup power supply capacity of the dual-drive variable pitch system is greatly increased, the charging time is shortened, and the variable pitch system quickly enters the ready state; at the same time, safety redundancy is achieved. When the main charger fails, the slave charger can still charge the backup power supply, and the variable pitch system can continue to operate, avoiding the loss of power generation due to unit shutdown, and improving the reliability of the dual-drive variable pitch system and even the wind turbine. It is worth noting that the two charging branches are interchangeable, and the master and slave can be exchanged.

[0058] Example 2

[0059] like Figures 1 to 3 As shown, as a further optimization of Example 1, this embodiment provides a control method for a backup power supply charging circuit of a wind turbine pitch control system:

[0060] A control method for a backup power supply charging circuit of a wind turbine pitch control system. When a main charger is in a fault state, a main control module and a slave control module are switched with each other, and a main charger and a slave charger are switched with each other.

[0061] When the main charger is in a faulty state, the master and slave charging circuits switch with each other to achieve safety redundancy. When the main charger fails, the slave charger can still charge the backup power supply and the pitch system can continue to operate, avoiding the loss of power generation due to unit shutdown and improving the reliability of the dual-drive pitch system and even the wind turbine.

[0062] As a preferred technical solution, when the main charger and the slave charger are in normal state, when the backup power supply voltage is lower than a% of the preset voltage value, the main charger and the slave charger charge the backup power supply with a constant current; wherein 50≤a≤95.

[0063] This makes it easy to increase the backup power supply charging input current, shorten the backup power supply charging time, improve the charging efficiency, and enable the backup power supply to enter a ready state as quickly as possible.

[0064] As a preferred technical solution, when the main charger and the slave charger are in normal state, when the backup power supply voltage is greater than a% of the preset voltage value and lower than 100%, the slave control module shuts off the output of the slave charger and only charges the backup power supply with a constant current through the main charger.

[0065] This makes it easier to maintain the backup power supply charging input current stable, achieve a smooth transition from constant current charging mode to constant voltage charging mode, and avoid charger or backup power supply failure caused by charging current output mismatch when two chargers switch from constant current charging mode to constant voltage charging mode at the same time.

[0066] As a preferred technical solution, when the main charger and the slave charger are both in normal state, when the backup power supply voltage reaches the preset voltage value for the first time, the output of the slave charger is shut down by the control module, and the backup power supply is charged at a constant voltage only by the main charger, so as to keep the backup power supply voltage stable within the range of b% to 100% of the preset value; wherein, 90≤b<100 and a<b.

[0067] This makes it easier to maintain the backup power supply voltage stable, ensuring that in the event of a power outage, the backup power supply is fully charged and stores enough energy to drive the variable pitch motor to drive the blades to achieve safe propeller alignment, thereby ensuring the safety of the unit.

[0068] As a preferred technical solution, a is set to 90 and b is set to 99.

[0069] As a preferred technical solution, when one of the main charger and the slave charger fails, when the backup power supply voltage is lower than 100% of the preset voltage value, the faulty charger shuts off the output by itself or through the connected control module, and only the normal charger charges the backup power supply with a constant current.

[0070] This makes it easy to charge the backup power supply at the fastest speed in the event of a charger failure, allowing the backup power supply to be ready as soon as possible, avoiding shutdown due to failure, reducing the charging failure rate, and the pitch control system only issues a single charger failure alarm, thereby improving the reliability of the pitch control system.

[0071] As a preferred technical solution, when one of the main charger and the slave charger fails, when the backup power supply voltage reaches the preset voltage value for the first time, the faulty charger shuts off the output by itself or through the connected control module, and only the normal charger charges the backup power supply at a constant voltage, keeping the backup power supply voltage stable within the range of b% to 100% of the preset value.

[0072] This makes it convenient for the backup power supply to be fully charged in the event of a charger failure or a grid power outage, storing enough energy to drive the pitch motor to drive the blades to achieve safe pitch alignment, ensuring the safety of the unit, avoiding failure shutdowns, and reducing the charging failure rate. The pitch system only issues a single charger failure alarm, improving the reliability of the pitch system.

[0073] As a preferred technical solution, it is characterized in that b is set to 99.

[0074] Example 3

[0075] like Figures 1 to 3 As shown, as a further optimization of Example 1 and Example 2, this example provides a more detailed implementation method.

[0076] The present invention discloses a backup power supply charging circuit for a wind turbine variable pitch system and a control method thereof. Figure 1 As shown, the charging circuit includes at least two charging circuits, a master circuit and a slave circuit. The master charging circuit is connected in sequence by a charger power supply, a main charger, a main diode, and a super capacitor module. The slave charging circuit is connected in sequence by a charger power supply, a slave charger, a slave diode, and a super capacitor module. At the same time, the voltage value of the super capacitor module is measured in real time by a voltage measurement module and sent to a main control module and a slave control module respectively through an analog signal. The main control module and the slave control module select a charging strategy to charge the super capacitor according to the current super capacitor module voltage and the charger state.

[0077] In this embodiment, there are three charger states, namely: 1. Both the master charger and the slave charger are in normal state; 2. The master charger is normal and the slave charger is faulty, or the master charger is faulty and the slave charger is normal, which is a normal state of a single charger; 3. Both the master charger and the slave charger are in faulty state or the supercapacitor module is in faulty state.

[0078] For the first state, the charging control strategy is as follows Figure 2 As shown, under the premise that the supercapacitor module is in normal state and the voltage measurement is normal, the control module controls the charger to charge the supercapacitor module through different charging modes according to the supercapacitor module voltage; when the voltage is lower than 90% of the preset voltage value, the main charger and the slave charger charge the supercapacitor module through the constant current mode; when the voltage is greater than or equal to 90% and lower than 100% of the preset voltage value, the main charger charges the supercapacitor module through the constant current mode, and the slave charger is turned off; when the voltage reaches 100% of the preset voltage value for the first time, the main charger charges the supercapacitor module through the constant voltage mode, keeps its voltage value stable within the range of 99% to 100% of the preset voltage value, and the slave charger is turned off.

[0079] For the second state, the charging control strategy is as follows Figure 3 As shown, under the premise that the supercapacitor module is in normal state and the voltage measurement is normal, the main charger is in normal state and the slave charger is in fault state; when the voltage is lower than 100% of the preset voltage value, the main charger charges the supercapacitor module through the constant current mode, and the slave charger is shut down due to fault; when the voltage reaches 100% of the preset voltage value for the first time, the main charger charges the supercapacitor module through the constant voltage mode, keeps its voltage value stable within the range of 99% to 100% of the preset voltage value, and the slave charger is shut down due to fault.

[0080] Furthermore, if the master charger is in a faulty state and the slave charger is in a normal state, the control software will switch the master / slave charging circuit according to the current state, that is, the master control module and the master charger are switched to the new slave control module and the slave charger, and the slave control module and the slave charger are switched to the new master control module and the master charger; when the voltage is lower than 100% of the preset voltage value, the new master charger charges the supercapacitor module through the constant current mode, and the new slave charger fails and shuts down; when the voltage reaches 100% of the preset voltage value for the first time, the new master charger charges the supercapacitor module through the constant voltage mode, keeps its voltage value stable within the range of 99% to 100% of the preset voltage value, and the new slave charger fails and shuts down.

[0081] In the third state, the charger cannot charge the supercapacitor and the wind turbine fails and shuts down.

[0082] In summary, in the examples of the present invention, under normal circumstances, the main charger and the slave charger charge the backup power supply according to the charging control strategy, which speeds up the charging speed, enables the variable pitch system to quickly enter the ready state, and reduces the commissioning time of the wind turbine; in the event of a single charger failure, safety redundancy can be achieved, and the backup power supply can be charged by another normal charger, thereby avoiding shutdown of the wind turbine due to failure and improving the reliability of the dual-drive variable pitch system and the wind turbine.

[0083] The purpose of the present invention is to propose a control method for charging a backup power supply through two chargers, thereby shortening the charging time of the backup power supply and enabling the variable pitch system to quickly complete charging and enter a ready state; at the same time, in the event of a failure of one charger, the other charger can still charge the backup power supply, and the variable pitch system can continue to operate, thereby achieving safety redundancy, avoiding the loss of power generation due to unit shutdown, and improving the reliability of the dual-drive variable pitch system and even the wind turbine.

[0084] The technical solution adopted by the present invention is as follows:

[0085] In the first possible implementation, a backup power supply charging circuit and a control method for a wind turbine pitch system are provided, characterized in that the backup power supply charging circuit of the dual-drive pitch system includes at least two master / slave charging circuits, and both charging circuits include at least a control module, a charger, and a diode, which together charge the backup power supply; the backup power supply voltage value is measured by a voltage measurement module and fed back to the control module, and the control module controls the charging mode and start and stop of the charger according to a preset charging control strategy based on the current voltage value of the backup power supply; at the same time, real-time information exchange is carried out between the master control module and the slave control module, and the master / slave charging circuit is switched according to the status of the master charger and the slave charger.

[0086] In combination with the first possible implementation, in a second possible implementation, the control module includes but is not limited to a separate controller, or a separate control card, or a controller integrated inside the pitch drive.

[0087] In combination with the first possible implementation, in a third possible implementation, the charger includes but is not limited to a separate charger, or a charger integrated inside the pitch drive;

[0088] In combination with the first possible implementation, in a fourth possible implementation, the input power source of the charger includes single-phase alternating current, two-phase alternating current, three-phase alternating current or direct current.

[0089] In combination with the first possible implementation, in a fifth possible implementation, the voltage measurement module includes but is not limited to a separate voltage measurement module, or a voltage measurement module integrated inside the driver.

[0090] In combination with the first possible implementation, in a sixth possible implementation, the pitch backup power supply includes but is not limited to a supercapacitor or a battery.

[0091] In combination with the sixth possible implementation method, in the seventh possible implementation method, when the pitch control system uses a supercapacitor as a backup power supply, it can be combined in series and parallel by capacitor modules of specific specifications.

[0092] In combination with the first implementable manner, in an eighth implementable manner, the information interaction method between the master control module and the slave control module includes but is not limited to an internal high-speed bus, CANOpen, and RS485.

[0093] In combination with the first possible implementation method, in a ninth possible implementation method, when the master charger is in a fault state, the master control module, the slave control module, the master charger, and the slave charger can be selected to switch in the control software, that is, the original main charging circuit can be switched to the slave charging circuit, and the slave charging circuit can be switched to the main charging circuit according to the control software.

[0094] In combination with the first possible implementation, in a tenth possible implementation, the voltage measurement module sends the backup power supply voltage value to the main control module and the slave control module in a manner including but not limited to CANOpen, or analog quantity.

[0095] In combination with the first possible implementation, in an eleventh possible implementation, the charging control strategy includes a normal state charging control strategy and a single-charger single-machine fault state charging control strategy.

[0096] In combination with the eleventh possible implementation, in the twelfth possible implementation, the normal state charging control strategy includes dual charger constant current charging, single charger constant current charging, and single charger constant voltage charging.

[0097] In combination with the twelfth possible implementation, in the thirteenth possible implementation, when the backup power supply voltage is lower than 90% of the preset voltage value, the charging control strategy is dual charger constant current charging, that is, both chargers charge the backup power supply with a constant current.

[0098] In combination with the twelfth possible implementation method, in the fourteenth possible implementation method, when the backup power supply voltage is greater than 90% and less than 100% of the preset voltage value, the charging control strategy is single charger constant current charging, that is, the slave charger output is shut down by the slave control module, and the backup power supply is charged with a constant current only by the main charger.

[0099] In combination with the twelfth possible implementation method, in the fifteenth possible implementation method, when the backup power supply voltage reaches the preset voltage value for the first time, the charging control strategy is single charger constant voltage charging, that is, the output of the slave charger is shut down by the control module, and the backup power supply is only charged at a constant voltage by the main charger, so as to keep the backup power supply voltage stable within the range of 99% to 100% of the preset value.

[0100] In combination with the eleventh possible implementation, in the sixteenth possible implementation, the charging control strategy in the single-charger single-machine fault state includes single-charger constant-current charging and single-charger constant-voltage charging.

[0101] In combination with the sixteenth possible implementation method, in the seventeenth possible implementation method, when the backup power supply voltage is lower than 100% of the preset voltage value, the charging control strategy is single charger constant current charging, that is, the faulty charger shuts off the output by itself or through the connected control module, and only the normal charger charges the backup power supply with a constant current.

[0102] In combination with the sixteenth possible implementation method, in the eighteenth possible implementation method, when the backup power supply voltage reaches the preset voltage value for the first time, the charging control strategy is single charger constant voltage charging, the faulty charger shuts off the output by itself or through the connected control module, and only the normal charger is used to charge the backup power supply at a constant voltage, keeping the backup power supply voltage stable within 99% to 100% of the preset value.

[0103] The control method adopted in the present invention controls two chargers and selects different strategies to charge the backup power supply according to the backup power supply status. When the backup power supply capacity of the dual-drive variable pitch system is greatly increased, the charging time is shortened, the variable pitch system is quickly put into a ready state, and the wind turbine debugging time is reduced.

[0104] The two chargers speed up the charging process while achieving safety redundancy. When one charger fails, the other can still charge the backup power supply and the variable pitch system can continue to operate, avoiding the loss of power generation due to unit shutdown and improving the reliability of the dual-drive variable pitch system and even the wind turbine.

[0105] As described above, the present invention can be preferably implemented.

[0106] The aforementioned main scheme of the present invention and its further options can be freely combined to form multiple schemes, all of which are schemes that can be adopted and claimed for protection by the present invention; and (each non-conflicting option) can also be freely combined with other options. After understanding the technical scheme of the present invention, those skilled in the art can understand that there are many combinations based on the prior art and common knowledge, all of which are technical schemes to be protected by the present invention, and they are not exhaustively listed here.

[0107] All features disclosed in all embodiments in this specification, or steps in all methods or processes implicitly disclosed, except for mutually exclusive features and / or steps, can be combined and / or expanded or replaced in any manner.

[0108] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. According to the technical essence of the present invention, within the spirit and principles of the present invention, any simple modification, equivalent replacement and improvement made to the above embodiment still falls within the protection scope of the technical solution of the present invention.

Claims

1. A backup power supply charging circuit for a wind turbine pitch control system, characterized in that: It includes a charger power supply, a backup power supply, n chargers, and n control modules. The charger power supply, each charger, and the backup power supply are electrically connected in sequence to form a branch. Each charger is electrically connected to a control module, and the n control modules are interconnected; wherein n is a positive integer and n≥2; n=2, the two chargers are respectively a master charger and a slave charger, and the two control modules are respectively a master control module and a slave control module; When the main charger is in a fault state, the main control module and the slave control module switch with each other, and the main charger and the slave charger switch with each other; When the main charger and the slave charger are both in normal state, when the backup power supply voltage is lower than a% of the preset voltage value, the main charger and the slave charger charge the backup power supply with a constant current; where 50≤a≤95; When both the master charger and the slave charger are in normal state, when the backup power supply voltage is greater than a% of the preset voltage value and less than 100%, the slave control module shuts down the slave charger output, and only charges the backup power supply with a constant current through the master charger; When the main charger and the slave charger are both in normal state, when the backup power supply voltage reaches the preset voltage value for the first time, the output of the slave charger is shut down by the control module, and the backup power supply is charged at a constant voltage only by the main charger, so as to keep the backup power supply voltage stable within the range of b% to 100% of the preset value; wherein, 90≤b<100 and a<b.

2. A backup power supply charging circuit for a wind turbine pitch control system according to claim 1, characterized in that: It also includes a voltage measurement module electrically connected to the backup power supply, and the voltage measurement module is also electrically connected to the n control modules respectively.

3. A wind turbine pitch control system backup power supply charging circuit according to claim 2, characterized in that: It also includes n unidirectional conductive elements. The charger power supply, each charger, each unidirectional conductive element, and the backup power supply are electrically connected in sequence to form a branch.

4. A backup power supply charging circuit for a wind turbine pitch control system according to claim 3, characterized in that: The unidirectional conductive element is a diode.

5. A method for controlling a backup power supply charging circuit of a wind turbine pitch control system according to any one of claims 1 to 4, characterized in that: Set a to 90 and b to 99.

6. A method for controlling a backup power supply charging circuit of a wind turbine pitch control system according to claim 1, characterized in that: When one of the main charger and the slave charger fails, when the backup power supply voltage is lower than 100% of the preset voltage value, the faulty charger shuts off the output by itself or through the connected control module, and only the normal charger charges the backup power supply with a constant current.

7. A method for controlling a backup power supply charging circuit of a wind turbine pitch control system according to claim 6, characterized in that: When one of the main charger and the slave charger fails, after the backup power supply voltage reaches the preset voltage value for the first time, the faulty charger shuts off the output by itself or through the connected control module, and only the normal charger charges the backup power supply at a constant voltage, keeping the backup power supply voltage stable within the range of b% to 100% of the preset value; where 90≤b<100.

8. A method for controlling a backup power supply charging circuit of a wind turbine pitch control system according to claim 7, characterized in that: Set b to 99.

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