A wind turbine blade pitch system and method

Abstract

The application discloses a wind power generation blade variable pitch system and method, comprising at least two variable pitch servo modules and three motors, each of the variable pitch servo modules comprises an AC / DC converter, a variable pitch controller, a backup power supply and at least two variable pitch servo units, the input end of the AC / DC converter is connected with alternating current, the variable pitch servo units and the backup power supply in the same variable pitch servo module are connected in parallel with the output end of the AC / DC converter, the variable pitch controllers of different variable pitch servo modules are connected in signal, the backup power supplies are connected in electricity, at least two variable pitch servo units are connected in electricity on each motor, and three blades are arranged on the three motors. Voltage, voltage change rate and voltage difference are acquired in real time to realize system assistance, supplement and replacement, the variable pitch system can automatically control the angle conversion of the blades, the safety and reliability of the variable pitch system are greatly improved, the cost is low, and installation, use and maintenance are facilitated.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of wind power generation, and particularly relates to a wind power generation blade variable pitch system and method. BACKGROUND

[0002] Wind power generation is a main form of new energy. Because wind energy has the characteristics of instability, low energy density and randomness, and wind power plants are usually located in remote areas or even offshore, the natural conditions are relatively poor, the wind is strong and the direction is changeable, so the control system must be able to realize automatic operation, and the control system must have high reliability. The variable pitch system is one of the core components of wind power generation.

[0003] Through the adjustment of the variable pitch system to the blades, the power generation power of the wind turbine and the load state of the wind turbine can be adjusted. When the wind is small and the wind turbine does not reach the maximum power generation power, the wind angle needs to be increased to increase the blade stress surface to maximize the use of wind power for power generation. When the wind is too large and exceeds the maximum power that the wind turbine can withstand, the wind angle needs to be reduced to reduce the blade stress surface, otherwise the wind turbine will be overloaded, causing damage to the generator, and even the wind turbine will collapse due to overspeed. When the wind turbine fails or the external wind environment is severe, the wind turbine is in a highly dangerous state, and if the blade wind angle cannot be quickly lowered to 0 degrees, the wind turbine will be in a risk state of out of control, and the speed will be too fast or the load will be unbalanced, which may even cause the wind turbine to collapse. Therefore, in the wind power generation system, the safety and reliability of the variable pitch system function belong to the highest level.

[0004] In the prior art, the electric variable pitch has a set of variable pitch servo system for each blade, which is powered by the AC power distribution of the wind turbine system to control the blade angle. In order to prevent power supply failure of the system, a battery or super capacitor is provided as a backup power supply for the variable pitch system. The variable pitch systems of each blade are independent of each other, and when the backup power supply or motor fails, the variable pitch system of the blade will lose function or function will be reduced. This leads to a decrease in the reliability of the entire wind turbine variable pitch system. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a wind power generation blade variable pitch system and method, which solves the problem of reduced reliability of the entire wind turbine system due to the independence of the blades in the prior art, and the system loses or reduces function when the backup power supply or motor fails.

[0006] The present application adopts the following technical solutions to solve the above technical problems:

[0007] The wind power generation blade variable pitch system comprises at least two variable pitch servo modules and three motors, each variable pitch servo module comprises an AC / DC converter, a variable pitch controller, a backup power supply and at least two variable pitch servo units, the input end of the AC / DC converter is connected with alternating current, the variable pitch servo units and the backup power supply in the same variable pitch servo module are connected in parallel with the output end of the AC / DC converter, the variable pitch controllers of different variable pitch servo modules are connected in signal, the backup power supplies are connected in electricity, the three blades are connected with the three motors one by one, each motor is a double-winding structure, and different variable pitch servo units are connected on each winding; and an electric energy control unit is arranged between each backup power supply and the input end of the variable pitch servo unit.

[0008] The variable pitch servo module comprises two, each variable pitch servo module comprises three variable pitch servo units, the three variable pitch servo units in the first variable pitch servo module are connected on one winding of the three motors one by one, and the three variable pitch servo units in the second variable pitch servo module are connected on the other winding of the three motors one by one.

[0009] The variable pitch servo module comprises three, each variable pitch servo module comprises two variable pitch servo units, and one variable pitch servo unit is connected on the two windings of each motor.

[0010] The variable pitch servo units connected on the same motor belong to the same variable pitch servo module.

[0011] The charger is connected in series between the backup power supply and the alternating current.

[0012] The energy control unit comprises but is not limited to a diode or a bidirectional DC / DC converter connected in series between the backup power supply and the input end of the variable pitch servo unit.

[0013] The wind power generation blade variable pitch method comprises the following steps:

[0014] Step 1, setting the bus voltage change rate threshold U t ′ h , the bus voltage difference threshold U Dth , the backup power supply voltage threshold U Bth and the output power threshold P r of the variable pitch servo module;

[0015] Step 2, acquiring the bus voltage, the voltage change rate of each bus, the voltage difference between buses, the voltage of each backup power supply and the output power of each variable pitch servo module in real time;

[0016] Step 3, judging the relationship between the voltage change rate of each bus, the voltage difference between buses, the backup power supply voltage and the output power of the variable pitch servo module and the respective threshold value in turn, and adjusting the output power of each module according to different relationships;

[0017] Step 4, repeat steps 2 to 3 to keep the output power of each module balanced.

[0018] The specific process of step 3 is as follows:

[0019] Step 3.1, determine whether the voltage rate of change of each bus reaches or exceeds the threshold value U t h If yes, execute step 3.2;

[0020] Step 3.2, gradually reduce the output power of the variable pitch servo module with the lowest voltage, and gradually increase the output power of the variable pitch servo module with the highest voltage; determine whether the voltage difference between buses reaches or exceeds the threshold value U Dth If yes, enable the backup power supply of the variable pitch servo system with low bus voltage, and execute step 3.3;

[0021] Step 3.3, determine whether the voltage of each backup power supply is lower than the threshold value U Bth If yes, execute step 3.4, otherwise, return to step 3.1;

[0022] Step 3.4, determine whether the output power of each variable pitch servo module is lower than the output power threshold P r If yes, make the backup power supply with high power output at maximum rated power, and make the backup power supply with low power enter power generation mode; otherwise, make the backup power supply with high power output at maximum rated power, and make the backup power supply with low power provide minimum output power;

[0023] Step 3.5, determine whether the voltage difference between buses is lower than the threshold value U Dth If yes, maintain the current power distribution ratio; otherwise, return to step 3.3.

[0024] After the backup power supply enters the power generation mode, the backup power supply is charged by alternating current or blade rotation.

[0025] If the voltage rate of change of more than one variable pitch servo module exceeds the corresponding threshold value, the output power of the corresponding module is gradually reduced in the order of time, and the output power of the former is always lower than that of the latter.

[0026] Compared with the prior art, the present application has the following beneficial effects:

[0027] 1. Through the redundant control of the electric control system, the safety of the wind power variable pitch system is improved:

[0028] Each blade is controlled by at least two servo units. When a fault occurs in the electric control components in a variable pitch system, other servo systems can still control the blades, reducing the safety risk of the wind turbine caused by the failure of a single servo system.​

[0029] 2. Enhance the safety of wind power pitch control systems through redundant control of backup power supplies:

[0030] Each blade has at least two backup power sources. If one backup power source is insufficient, the other backup power sources can support the operation of the pitch system, reducing the safety risks to the wind turbine caused by the failure of a single pitch system.

[0031] 3. Each pitch module can operate in both electric and generator modes. Multiple pitch modules on a single motor can interconnect via the motor, maintaining backup power and improving the safety and reliability of the pitch system. This also reduces the capacity of the backup power supply and lowers system costs. In cases where pitch power is insufficient due to special operating conditions, backup power can be maintained through energy interaction. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the technical description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram of the wind power generation blade pitch system in Embodiment 1 of the present invention.

[0034] Figure 2 This is a schematic diagram of the wind power generation blade pitch system in Embodiment 2 of the present invention.

[0035] Figure 3 This is a schematic diagram of the wind power generation blade pitch system in Embodiment 3 of the present invention.

[0036] Figure 4 This is a schematic diagram of the wind power generation blade pitch system in Embodiment 4 of the present invention.

[0037] Figure 5 The present invention provides a flowchart of the wind power generation blade pitch control method. Figure 1 .

[0038] Figure 6 The present invention provides a flow chart for a wind power blade pitch control method. Figure 2 .

[0039] Wherein, the marks in the figure are: 11-first variable pitch servo module, 12-second variable pitch servo module, 13-third variable pitch servo module, 21-first AC / DC converter, 22-second AC / DC converter, 23-third AC / DC converter, 31-first variable pitch servo unit, 32-second variable pitch servo unit, 33-third variable pitch servo unit, 34-fourth variable pitch servo unit, 35-fifth variable pitch servo unit, 36-sixth variable pitch servo unit, 41-first variable pitch controller, 42-second variable pitch controller, 43-third variable pitch controller, 51-first charger, 52-second charger, 53-third charger, 61-first backup power supply, 62-second backup power supply, 63-third backup power supply, 71-first diode, 72-second diode, 73-third diode, 81-first motor, 82-first speed reducer, 83-first blade, 84-second motor, 85-second speed reducer, 86-second blade, 87-third motor, 88-third speed reducer, 89-third blade, 91-first bidirectional DC / DC unit, 92-second bidirectional DC / DC unit, 93-third bidirectional DC / DC unit. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0041] A wind power generation blade variable pitch system, comprising at least two variable pitch servo modules and three motors, each variable pitch servo module comprising an AC / DC converter, a variable pitch controller, a backup power supply and at least two variable pitch servo units, the input end of the AC / DC converter being connected with alternating current, the variable pitch servo units and the backup power supply in the same variable pitch servo module being connected in parallel to the output end of the AC / DC converter, the variable pitch controllers of different variable pitch servo modules being signal connected, the backup power supplies being electrically connected, the three blades being connected with the three motors one by one, each motor being a double-winding structure, different variable pitch servo units being connected on each winding; an electric energy control unit being arranged between each backup power supply and the input end of the variable pitch servo unit.

[0042] Specific embodiment one, as Figure 1 shown,

[0043] Referring to Figure 1 shown, the present embodiment discloses a wind power generation blade variable pitch system, comprising a first variable pitch servo module 11, a second variable pitch servo module 12, a first motor 81, a second motor 84 and a third motor 87.

[0044] The first variable pitch servo module 11 comprises a first AC / DC converter 21, a first variable pitch servo unit 31, a second variable pitch servo unit 32, a third variable pitch servo unit 33, a first variable pitch controller 41 and a first backup power supply 61.

[0045] The first AC / DC converter 21 is connected with the alternating current and is used to convert the alternating current into direct current and supply power to the first variable pitch servo unit 31, the second variable pitch servo unit 32, the third variable pitch servo unit 33 and the first variable pitch controller 41 after voltage stabilization and filtering.

[0046] The input ends of the first variable pitch servo unit 31, the second variable pitch servo unit 32 and the third variable pitch servo unit 33 are connected in parallel to the output end of the first AC / DC converter 21. The output ends of the first variable pitch servo unit 31, the second variable pitch servo unit 32 and the third variable pitch servo unit 33 are respectively connected to the input ends of the first motor 81, the second motor 84 and the third motor 87. The first variable pitch servo unit 31, the second variable pitch servo unit 32 and the third variable pitch servo unit 33 can respectively drive the first motor 81, the second motor 84 and the third motor 87.

[0047] The first backup power supply 61 is connected to the output end of the first AC / DC converter 21. When the alternating current is normally input, the first backup power supply 61 is in a charging state or a standby state; when the alternating current is abnormal, the first backup power supply 61 supplies power to the first variable pitch servo unit 31, the second variable pitch servo unit 32, the third variable pitch servo unit 33 and the first variable pitch controller 41; when the first backup power supply 61 is in a low-voltage state, the system charges the first backup power supply 61.

[0048] In order to ensure the safety of the first backup power supply 61, improve its service life and avoid the problem that the backup power supply fails due to overcharging when a single variable pitch motor is in a power generation state for a long time, a first charger 51 can be connected in series between the above-mentioned alternating current and the first backup power supply 61. A first diode 71 is connected in series between the output end of the first AC / DC converter 21 and the first backup power supply 61. The conduction direction of the first diode 71 is from the first backup power supply 61 to the first variable pitch servo unit 31, the second variable pitch servo unit 32 and the third variable pitch servo unit 33. The first diode 71 reduces the disturbance of the first backup power supply 61 to the circuit in a non-power supply state.

[0049] The second variable pitch servo module 12 comprises a second AC / DC converter 22, a fourth variable pitch servo unit 34, a fifth variable pitch servo unit 35, a sixth variable pitch servo unit 36, a second variable pitch controller 42 and a second backup power supply 62.

[0050] The second AC / DC converter 22 is connected to the AC power supply and is used to convert the AC power into DC power and supply the fourth pitch servo unit 34, the fifth pitch servo unit 35, the sixth pitch servo unit 36 and the second pitch controller 42 after voltage stabilization and filtering.

[0051] The input terminals of the fourth pitch servo unit 34, the fifth pitch servo unit 35 and the sixth pitch servo unit 36 are connected in parallel to the output terminal of the second AC / DC converter 22. The output terminals of the fourth pitch servo unit 34, the fifth pitch servo unit 35 and the sixth pitch servo unit 36 are connected to the input terminals of the first motor 81, the second motor 84 and the third motor 87 respectively. The fourth pitch servo unit 34, the fifth pitch servo unit 35 and the sixth pitch servo unit 36 can drive the first motor 81, the second motor 84 and the third motor 87 respectively.

[0052] The second backup power supply 62 is connected to the output terminal of the second AC / DC converter 22. When the AC power supply is normal, the second backup power supply 62 is in a charging state or a standby state; when the AC power supply is abnormal, the second backup power supply 62 supplies power to the fourth pitch servo unit 34, the fifth pitch servo unit 35, the sixth pitch servo unit 36 and the second pitch controller 42; when the second backup power supply 62 is in a low voltage state, the system charges the second backup power supply 62.

[0053] In order to ensure the safety of the second backup power supply 62, improve its service life and avoid the problem that the backup power supply fails due to overcharging when a single pitch motor is in a power generation state for a long time, a second charger 52 can be connected in series between the AC power supply and the second backup power supply 62. A second diode 72 is connected in series between the output terminal of the second AC / DC converter 22 and the second backup power supply 62. The conduction direction of the second diode 72 is from the second backup power supply 62 to the fourth pitch servo unit 34, the fifth pitch servo unit 35 and the sixth pitch servo unit 36. The second diode 72 reduces the disturbance of the second backup power supply 62 to the circuit in a non-power supply state.

[0054] The first and second variable pitch controllers 41 and 42 are in communication connection. The first variable pitch controller 41 is configured to control the first, second and third variable pitch servo units 31, 32 and 33 to perform servo driving. The second variable pitch controller 42 is configured to control the fourth, fifth and sixth variable pitch servo units 34, 35 and 36 to perform servo driving. When the first variable pitch controller 41 fails, the second variable pitch controller 42 controls the first, second and third variable pitch servo units 31, 32 and 33 to perform servo driving. When the second variable pitch controller 42 fails, the first variable pitch controller 41 controls the fourth, fifth and sixth variable pitch servo units 34, 35 and 36 to perform servo driving.

[0055] The first and second backup power supplies 61 and 62 are in electrical connection. This realizes mutual backup between the backup power supplies, and enables energy exchange between the two variable pitch servo modules, thereby solving the risk caused by the capacity of the backup power supply and ensuring that the two variable pitch servo modules can work normally.

[0056] The first motor 81 is provided with a first speed reducer 82. The first blade 83 is connected to the first speed reducer 82. The first variable pitch servo unit 31 can servo drive the first motor 81, the first motor 81 can drive the first speed reducer 82, and the first speed reducer 82 can make the first blade 83 change the angle to adapt to the wind force and direction in real time. When the first variable pitch servo unit 31 fails, the fourth variable pitch servo unit 34 can replace the first variable pitch servo unit 31 to servo drive the first motor 81.

[0057] The second motor 84 is provided with a second speed reducer 85. The second blade 86 is connected to the second speed reducer 85. The second variable pitch servo unit 32 can servo drive the second motor 84, the second motor 84 can drive the second speed reducer 85, and the second speed reducer 85 can make the second blade 86 change the angle to adapt to the wind force and direction in real time. When the second variable pitch servo unit 32 fails, the fifth variable pitch servo unit 35 can replace the second variable pitch servo unit 32 to servo drive the second motor 84.

[0058] The third motor 87 is provided with a third speed reducer 88. The third blade 89 is connected to the third speed reducer 88. The third variable pitch servo unit 33 can servo drive the third motor 87, the third motor 87 can drive the third speed reducer 88, and the third speed reducer 88 can make the third blade 89 change the angle to adapt to the wind force and direction in real time. When the third variable pitch servo unit 33 fails, the sixth variable pitch servo unit 36 can replace the third variable pitch servo unit 33 to servo drive the third motor 87.

[0059] The first motor 81, the second motor 84 and the third motor 87 are motors having at least two isolated windings.

[0060] The above controls the working of the motor and the angle of the blade by controlling one winding of the motor through two pitch servo respectively. Compared with the traditional double-drive electric pitch system, the redundancy of the motor and the electric control is reduced, the number of the motor is reduced, and the complexity of the mechanism is reduced. In the face of the difference of the device condition of each pitch system, the condition and working condition of the backup power supply, the energy of the backup power supply of each pitch system can be interchanged without reserving enough energy for each. The problem of losing the control function of the angle of the blade and causing the safety risk of the fan after the failure of the electric control part of one pitch servo system is avoided; at the same time, the backup power supply of the pitch system avoids the problem of losing the control function of the angle of the blade and causing the safety risk of the fan after the failure or energy shortage of the backup power supply in the emergency pitch; on the one hand, the safety and reliability of the internal electric control unit are improved, and on the other hand, the safety and reliability of the backup power supply and the standby energy are improved, so that the reliability and safety of the whole pitch system are greatly improved.

[0061] Specific embodiment two, as Figure 2 shown,

[0062] Referring to Figure 2 shown, the embodiment discloses a wind power blade pitch system, which is different from the embodiment one in that a first bidirectional DC / DC unit 91 is used to replace the first charger 51 and the first diode 71, the first bidirectional DC / DC unit 91 is connected in series between the input ends of the first backup power supply 61 and the first pitch servo unit 31, the second pitch servo unit 32 and the third pitch servo unit 33. A second bidirectional DC / DC unit 92 is used to replace the second charger 52 and the second diode 72, the second bidirectional DC / DC unit 92 is connected in series between the input ends of the second backup power supply 62 and the fourth pitch servo unit 34, the fifth pitch servo unit 35 and the sixth pitch servo unit 36. The first bidirectional DC / DC unit 91 and the second bidirectional DC / DC unit 92 can make the first backup power supply 61 and the second backup power supply 62 in the charging state when the alternating current normally works, and disconnect the circuit after being fully charged, so that the first backup power supply 61 and the second backup power supply 62 are in the standby state; when the first backup power supply 61 and the second backup power supply 62 need to supply power, the first bidirectional DC / DC unit 91 and the second bidirectional DC / DC unit 92 can normally supply power to the pitch servo module and the motor.

[0063] Specific embodiment three, as Figure 3 shown,

[0064] Referring to Figure 3As shown, the embodiment discloses a wind power generation blade variable pitch system, comprising a first variable pitch servo module 11, a second variable pitch servo module 12, a third variable pitch servo module 13, a first motor 81, a second motor 84, and a third motor 87.

[0065] The first variable pitch servo module 11 comprises a first AC / DC converter 21, a first variable pitch servo unit 31, a second variable pitch servo unit 32, a first variable pitch controller 41, and a first backup power supply 61.

[0066] The first AC / DC converter 21 is connected with alternating current, used to convert alternating current into direct current, and supply power to the first variable pitch servo unit 31, the second variable pitch servo unit 32, and the first variable pitch controller 41 after voltage stabilization and filtering.

[0067] The input ends of the first variable pitch servo unit 31 and the second variable pitch servo unit 32 are connected in parallel to the output end of the first AC / DC converter 21. The output ends of the first variable pitch servo unit 31 and the second variable pitch servo unit 32 are respectively connected to the input ends of the first motor 81, the second motor 84, and the third motor 87. The first variable pitch servo unit 31 and the second variable pitch servo unit 32 can respectively drive the first motor 81, the second motor 84, and the third motor 87.

[0068] The first backup power supply 61 is connected to the output end of the first AC / DC converter 21. When the alternating current is normally input, the first backup power supply 61 is in a charging state or a standby state; when the alternating current is abnormal, the first backup power supply 61 supplies power to the first variable pitch servo unit 31, the second variable pitch servo unit 32, and the first variable pitch controller 41; when the first backup power supply 61 is in a low-voltage state, the system charges the first backup power supply 61.

[0069] In order to ensure the safety of the first backup power supply 61, improve its service life, and avoid the problem that the standby power supply fails due to overcharging when a single variable pitch motor is in a power generation state for a long time, a first charger 51 can be connected in series between the alternating current and the first backup power supply 61. A first diode 71 is connected in series between the output end of the first AC / DC converter 21 and the first backup power supply 61. The conduction direction of the first diode 71 is from the first backup power supply 61 to the first variable pitch servo unit 31 and the second variable pitch servo unit 32. The first diode 71 reduces the disturbance of the first backup power supply 61 to the circuit in a non-power supply state.

[0070] The second variable pitch servo module 12 comprises a second AC / DC converter 22, a third variable pitch servo unit 33, a fourth variable pitch servo unit 34, a second variable pitch controller 42, and a second backup power supply 62.

[0071] The second AC / DC converter 22 is connected to the AC power supply and is used to convert the AC power into DC power and supply the third and fourth pitch servo units 33 and 34 and the second pitch controller 42 after voltage stabilization and filtering.

[0072] The input terminals of the third and fourth pitch servo units 33 and 34 are connected in parallel to the output terminal of the second AC / DC converter 22. The output terminals of the third and fourth pitch servo units 33 and 34 are connected to the input terminals of the first, second and third motors 81, 84 and 87, respectively. The third and fourth pitch servo units 33 and 34 can drive the first, second and third motors 81, 84 and 87, respectively.

[0073] The second backup power supply 62 is connected to the output terminal of the second AC / DC converter 22. When the AC power is normally input, the second backup power supply 62 is in a charging state or a standby state; when the AC power is abnormal, the second backup power supply 62 supplies power to the third and fourth pitch servo units 33 and 34 and the second pitch controller 42; when the second backup power supply 62 is in a low voltage state, the system charges the second backup power supply 62.

[0074] In order to ensure the safety of the second backup power supply 62, improve its service life, and avoid the problem that a single pitch motor in a power generation state for a long time charges the backup power supply, causing the backup power supply to malfunction due to overcharging, a second charger 52 can be connected in series between the AC power and the second backup power supply 62. A second diode 72 is connected in series between the output terminal of the second AC / DC converter 22 and the second backup power supply 62. The conduction direction of the second diode 72 is from the second backup power supply 62 to the third and fourth pitch servo units 33 and 34. The second diode 72 reduces the disturbance of the second backup power supply 62 to the circuit in a non-power supply state.

[0075] The third pitch servo module 13 includes a third AC / DC converter 23, a fifth pitch servo unit 35, a sixth pitch servo unit 36, a third pitch controller 43 and a third backup power supply 63.

[0076] The third AC / DC converter 23 is connected to the AC power supply and is used to convert the AC power into DC power and supply the fifth and sixth pitch servo units 35 and 36 and the third pitch controller 43 after voltage stabilization and filtering.

[0077] The input terminals of the fifth and sixth variable-pitch servo units 35 and 36 are connected in parallel to the output terminal of the third AC / DC converter 23. The output terminals of the fifth and sixth variable-pitch servo units 35 and 36 are connected to the input terminals of the first, second and third electric motors 81, 84 and 87, respectively. The fifth and sixth variable-pitch servo units 35 and 36 can drive the first, second and third electric motors 81, 84 and 87, respectively.

[0078] The third backup power supply 63 is connected to the output terminal of the third AC / DC converter 23. When normal AC power is input, the third backup power supply 63 is in a charging state or a standby state; when abnormal AC power is input, the third backup power supply 63 supplies power to the fifth and sixth variable-pitch servo units 35 and 36 and the third variable-pitch controller 43; and when the third backup power supply 63 is in a low-voltage state, the system charges the third backup power supply 63.

[0079] To ensure the safety of the third backup power supply 63 and improve its service life, and to avoid the problem of overcharging of the backup power supply when a single variable-pitch motor is in a power generation state for a long time, a third charger 53 can be connected in series between the AC power and the third backup power supply 63. A third diode 73 is connected in series between the output terminal of the third AC / DC converter 23 and the third backup power supply 63. The conduction direction of the third diode 73 is from the third backup power supply 63 to the fifth and sixth variable-pitch servo units 35 and 36. The third diode 73 reduces the disturbance of the third backup power supply 63 to the circuit in a non-power supply state.

[0080] The first, second and third variable-pitch controllers 41, 42 and 43 are communicatively connected. The first variable-pitch controller 41 is configured to control the first and second variable-pitch servo units 31 and 32 to perform servo driving. The second variable-pitch controller 42 is configured to control the third and fourth variable-pitch servo units 33 and 34 to perform servo driving. The third variable-pitch controller 43 is configured to control the fifth and sixth variable-pitch servo units 35 and 36 to perform servo driving. When the first variable-pitch controller 41 fails, the second or third variable-pitch controller 42 or 43 controls the first and second variable-pitch servo units 31 and 32 to perform servo driving. When the second variable-pitch controller 42 fails, the first or third variable-pitch controller 41 or 43 controls the third and fourth variable-pitch servo units 33 and 34 to perform servo driving. When the third variable-pitch controller 43 fails, the first or second variable-pitch controller 41 or 42 controls the fifth and sixth variable-pitch servo units 35 and 36 to perform servo driving.

[0081] The first backup power supply 61, the second backup power supply 62 and the third backup power supply 63 are electrically connected. This realizes mutual backup between backup power supplies, enables energy exchange between two variable pitch servo modules, solves the risk caused by backup power supply capacity, and ensures that both variable pitch servo modules can work normally.

[0082] The first motor 81 is provided with a first speed reducer 82. The first blade 83 is connected with the first speed reducer 82. The first variable pitch servo unit 31 can servo drive the first motor 81, the first motor 81 can drive the first speed reducer 82, the first speed reducer 82 can make the first blade 83 change angle to adapt to wind force and wind direction in real time; when the first variable pitch servo unit 31 fails, the second variable pitch servo unit 32 can replace the first variable pitch servo unit 31 to servo drive the first motor 81.

[0083] The second motor 84 is provided with a second speed reducer 85. The second blade 86 is connected with the second speed reducer 85. The third variable pitch servo unit 32 can servo drive the second motor 84, the second motor 84 can drive the second speed reducer 82, the second speed reducer 85 can make the second blade 86 change angle to adapt to wind force and wind direction in real time; when the third variable pitch servo unit 33 fails, the fourth variable pitch servo unit 34 can replace the third variable pitch servo unit 33 to servo drive the second motor 84.

[0084] The third motor 87 is provided with a third speed reducer 88. The third blade 89 is connected with the third speed reducer 88. The fifth variable pitch servo unit 35 can servo drive the third motor 87, the third motor 87 can drive the third speed reducer 87, the third speed reducer 88 can make the third blade 89 change angle to adapt to wind force and wind direction in real time; when the fifth variable pitch servo unit 35 fails, the sixth variable pitch servo unit 36 can replace the fifth variable pitch servo unit 35 to servo drive the third motor 87.

[0085] The first motor 81, the second motor 84 and the third motor 87 are motors with at least two isolated windings.

[0086] The above controls the motor and the angle of the blade by three variable pitch servos to control one winding of the motor. The variable pitch system driven by a single variable pitch servo has only one set of variable pitch system for each blade, and each system includes three main components: a variable pitch servo driver, a variable pitch motor, and a backup power supply. When any of the three main components fails, the variable pitch system will lose its function. Since the forces on the three blades are inconsistent, the energy consumed by the variable pitch system of each blade is also inconsistent. In addition, due to the differences in the device condition of each variable pitch system, the condition and working condition of the backup power supply itself, the energy of the three backup power supplies cannot be guaranteed to be consistent. In order to ensure that the energy of the backup power supply of each variable pitch system is within a safe range when the backup power supply is used for emergency pitch, sufficient energy needs to be reserved. When a backup power supply fails or its life is attenuated, the backup power supply needs to be replaced immediately. Therefore, by using two variable pitch servos, the problem of losing control of the angle of the blade and causing safety risks of the fan due to the failure of the electrical control components of a variable pitch servo system is avoided. At the same time, the backup power supply serves as a backup for each other, avoiding the problem of losing control of the angle of the blade and causing safety risks of the fan due to the failure of the backup power supply of the variable pitch system or insufficient energy in the emergency pitch. The reliability and safety of the variable pitch system are greatly improved.

[0087] In a specific embodiment four, as shown in Figure 4

[0088] Referring to Figure 4 ​As shown, the embodiment discloses a wind power generation blade variable pitch system, which is different from the third embodiment in that the first bidirectional DC / DC unit 91 is used to replace the first charger 51 and the first diode 71, the first bidirectional DC / DC unit 91 is connected in series between the first backup power supply 61 and the input ends of the first variable pitch servo unit 31 and the second variable pitch servo unit 32. The second bidirectional DC / DC unit 92 is used to replace the second charger 52 and the second diode 72, the second bidirectional DC / DC unit 92 is connected in series between the second backup power supply 62 and the input ends of the third variable pitch servo unit 33 and the fourth variable pitch servo unit 34. The third bidirectional DC / DC unit 93 is used to replace the third charger 53 and the third diode 73, the third bidirectional DC / DC unit 93 is connected in series between the third backup power supply 63 and the input ends of the fifth variable pitch servo unit 35 and the sixth variable pitch servo unit 36. The first bidirectional DC / DC unit 91, the second bidirectional DC / DC unit 92 and the third bidirectional DC / DC unit 93 can make the first backup power supply 61, the second backup power supply 62 and the third backup power supply 63 in the charging state when the alternating current is normally working, and disconnect the circuit after being fully charged, so that the first backup power supply 61, the second backup power supply 62 and the third backup power supply 63 are in the standby state; when the first backup power supply 61, the second backup power supply 62 and the third backup power supply 63 need to be powered, the first bidirectional DC / DC unit 91, the second bidirectional DC / DC unit 92 and the third bidirectional DC / DC unit 93 can make the first backup power supply 61, the second backup power supply 62 and the third backup power supply 63 normally power the variable pitch servo module and the motor.

[0089] Based on the system described in the above embodiment, the application further discloses a wind power generation blade variable pitch method, comprising the following steps:

[0090] Step 1, setting the bus voltage change rate threshold U' th , the bus voltage difference threshold U Dth , the backup power supply voltage threshold U Bth and the output power threshold P r of the variable pitch servo module;

[0091] Step 2, obtaining the bus voltage, the voltage change rate of each bus, the voltage difference between each bus, the voltage of each backup power supply and the output power of each variable pitch servo module in real time;

[0092] Step 3, judging the relationship between the voltage change rate of each bus, the voltage difference between each bus, the backup power supply voltage and the output power of the variable pitch servo module and the respective threshold value in turn, and adjusting the output power of each module according to different relationships;

[0093] Step 4, repeatedly executing steps 2 to 3 to keep the output power of each module of the system in a balanced state.

[0094] Specific embodiment five, such as Figure 5 As shown,

[0095] Reference Figure 5 As shown, this embodiment discloses a method for wind turbine blade pitch control, using the wind turbine blade pitch control system in Embodiment 1 or Embodiment 2, including the following steps:

[0096] S1, Real-time acquisition of the first bus voltage U bus1 Second bus voltage U bus2 Voltage change rate U′ of the first bus t1 The voltage change rate U′ of the second bus t2 and the voltage difference U between the first bus and the second bus 12 .

[0097] Specifically, the first bus voltage U bus1 Second bus voltage U bus2 These are the output voltages of the first AC / DC converter 21 and the second AC / DC converter 22, respectively. Real-time readings are obtained using an external voltmeter.

[0098] The voltage change rate U′ of the first busbar t1 The rate of change of the voltage of the first busbar with time is given by the following formula:

[0099] U′ t1 =dU bus1 / dt (1)

[0100] The voltage change rate U′ of the second busbar t2 The rate of change of the voltage of the second busbar with time is given by the following formula:

[0101] U′ t2 =dU bus2 / dt (2)

[0102] The voltage difference U between the first busbar and the second busbar 12 This is the absolute value of the difference between the voltage of the first bus and the real-time voltage of the second bus, and its specific calculation formula is as follows:

[0103] U 12 =|U bus1 -U bus2 | (3)

[0104] S2, set the threshold U′ for the rate of change of voltage. th And determine the voltage change rate U′ of the first bus. t1 Or the voltage change rate U′ of the second bus t2whether the threshold value is reached or exceeded; if yes, gradually reduce the output power of the lowest voltage variable pitch servo module and gradually increase the output power of the high voltage variable pitch servo module to maintain the total power unchanged and enter S3; if no, return to S1.

[0105] threshold value U' th Depending on the capacity and life of the system's own backup power supply, the system's own state is reacted to, and the system's parameters are specifically set in combination with the parameter values.

[0106] For example, if the voltage rate of change U' t1 reaches or exceeds the threshold value U' th , the output power of the first variable pitch servo module 11 is gradually reduced, and the output power of the second variable pitch servo module 12 is gradually increased to maintain the total power unchanged.

[0107] Similarly, if the voltage rate of change U' t2 reaches or exceeds the threshold value U' th , the output power of the second variable pitch servo module 12 is gradually reduced, and the output power of the first variable pitch servo module 11 is gradually increased to maintain the total power unchanged.

[0108] This process realizes multiple insurance, improves the safety and reliability of the system.

[0109] S3, set the threshold value U Dth of the voltage difference, and judge whether the voltage difference U 12 of the first bus and the second bus reaches or exceeds the threshold value U Dth ; if yes, enable the backup power supply of the variable pitch servo system with the lower bus voltage, and enter S4; if no, return to S1.

[0110] For example, if the voltage difference U 12 reaches or exceeds the threshold value U Dth , compare the size of the first bus voltage U bus1 and the second bus voltage U bus2 ; if the first bus voltage U bus1 is less than the second bus voltage U bus2 , enable the first backup power supply 61, otherwise enable the second backup power supply 62.

[0111] This process enables the backup power supply to supplement the output voltage of the AC power supply and the AC / DC converter in the case of gradually increasing the voltage difference between the buses, so that each variable pitch servo module returns to the normal working state, and improves the safety and reliability of the system.

[0112] S4, real-time acquisition of the voltage U bat1 of the first backup power supply 61 and the voltage U bat2Set the backup power threshold U Bth And determine the voltage U of the first backup power supply 61. bat1 Or the voltage U of the second backup power supply 62 bat2 Is it below the threshold U? Bth If yes, proceed to S5; otherwise, gradually reduce the output power of the backup power supply with the lowest voltage and gradually increase the output power of the backup power supply with the highest voltage to maintain the total power unchanged, and then proceed to S6.

[0113] For example, if voltage U bat1 Below the threshold U Bth Then, the output power of the first backup power supply 61 is gradually reduced, and the output power of the second backup power supply 62 is gradually increased to maintain the total power unchanged.

[0114] Similarly, if voltage U bat2 Below the threshold U Bth Then, the output power of the second backup power supply 62 is gradually reduced, and the output power of the first backup power supply 61 is gradually increased to maintain the total power unchanged.

[0115] This process reduces dependence on backup power sources that are gradually losing energy, avoids the impact on the system during energy loss, and improves the system's safety and stability.

[0116] S5, Real-time acquisition of the output power P of the first pitch servo module 11 real1 The output power P of the second pitch servo module 12 real2 Set the output power threshold P of the pitch servo module. r And determine the output power P of the first pitch servo module 11. real1 Or the output power P of the second pitch servo module 12 real2 Is it below the output power threshold P? r If yes, the backup power supply with higher power outputs at its maximum rated power, while the backup power supply with lower power enters the power generation mode and enters S6; if no, the backup power supply with higher power outputs at its maximum rated power, while the backup power supply with lower power provides the minimum output power.

[0117] After entering power generation mode, the backup power supply gradually increases in energy and voltage by relying on alternating current or blade rotation for charging, until the voltage exceeds the threshold U. Bth Then, the backup power supply was reactivated.

[0118] For example, if the output power P real1 Below the output power threshold P r This causes the second backup power supply 62 to output at its maximum rated power, thus enabling the first backup power supply 61 to enter power generation mode.

[0119] Similarly, if the output power P real2 Below the output power threshold P r This causes the first backup power supply 61 to output at its maximum rated power, and the second backup power supply 62 to enter the power generation mode.

[0120] If the output power P real1 Not lower than the output power threshold P r This will cause the second backup power supply 62 to output at its maximum rated power, while the first backup power supply 61 will provide its minimum output power.

[0121] Similarly, if the output power P real2 Not lower than the output power threshold P r This will cause the first backup power supply 61 to output at its maximum rated power, and the second backup power supply 62 to provide its minimum output power.

[0122] This process reduces reliance on the backup power supply when voltage decay occurs, but all pitch servo modules are still functioning normally, thus avoiding system impact during voltage decay and improving system safety and stability. When the backup power supply experiences voltage decay and is insufficient to support the normal operation of all pitch servo modules, the output of the backup power supply with the lowest output power is quickly cut off, putting it into generator mode to restore power supply as quickly as possible and save the entire wind turbine.

[0123] S6, determine the voltage difference U between the first busbar and the second busbar. 12 Is it below the threshold U? Dth If yes, maintain the current power allocation ratio; otherwise, return to step S4.

[0124] This embodiment provides multiple solutions to problems in the entire pitch servo system. By considering the bus voltage, the rate of change of the bus voltage, the voltage difference between the buses, the backup power supply voltage, and the pitch servo module, it comprehensively considers the parameters that have a significant impact on the system. It forms multiple auxiliary, supplementary, and replacement schemes between AC power supplies, between backup power supplies, and between AC power supplies and backup power supplies, which greatly improves the safety and reliability of the system and reduces system redundancy.

[0125] Specific embodiment six, such as Figure 6 As shown,

[0126] Reference Figure 6 As shown, this embodiment discloses a method for wind turbine blade pitch control, using the wind turbine blade pitch control system in Embodiment 3 or Embodiment 4, including the following steps:

[0127] S1, Real-time acquisition of the first bus voltage U bus1 Second bus voltage U bus2 Third bus voltage Ubus3 , the voltage rate of change U t '1 of the first bus t '2, the voltage rate of change U t '3 of the first bus and the second bus 12 , the voltage difference U 13 of the first bus and the third bus 23 .

[0128] Specifically, the first bus voltage U bus1 , the second bus voltage U bus2 and the third bus voltage U bus3 are the output voltages of the first AC / DC converter 21, the second AC / DC converter 22 and the third AC / DC converter 23, respectively. Real-time readings are taken by an external voltmeter.

[0129] The voltage rate of change U t '1 of the first bus is the speed of change of the voltage of the first bus over time, and its specific calculation formula is:

[0130] U' t1 = dU bus1 / dt (4)

[0131] The voltage rate of change U t2 '2 of the second bus is the speed of change of the voltage of the second bus over time, and its specific calculation formula is:

[0132] U' t2 = dU bus2 / dt (5)

[0133] The voltage rate of change U t3 '3 of the third bus is the speed of change of the voltage of the third bus over time, and its specific calculation formula is:

[0134] U' t3 = dU bus3 / dt (6)

[0135] The voltage difference U 12 '3 of the first bus and the second bus is the absolute value of the difference between the voltage of the first bus and the real-time voltage of the second bus, and its specific calculation formula is:

[0136] U 12 = |U bus1 -U bus2 | (7)

[0137] The voltage difference U 13This is the absolute value of the difference between the voltage of the first bus and the real-time voltage of the third bus, and its specific calculation formula is as follows:

[0138] U 13 =|U bus1 -U bus3 | (8)

[0139] The voltage difference U between the second bus and the third bus 23 This is the absolute value of the difference between the voltage of the second bus and the real-time voltage of the third bus, and its specific calculation formula is as follows:

[0140] U 23 =|U bus2 -U bus3 | (9)

[0141] S2, set the threshold U′ for the rate of change of voltage. th And determine the voltage change rate U′ of the first bus. t1 The voltage change rate U′ of the second bus t2 Or the voltage change rate U′ of the third bus t3 If the threshold is reached or exceeded, the output power of the pitch servo module with the lowest voltage is gradually reduced, and the output power of the pitch servo module with the highest voltage is gradually increased to maintain the total power constant, and then proceed to S3; otherwise, return to S1.

[0142] Threshold U′ th It depends on the capacity and lifespan of the system's own backup power supply, and reflects the system's own status. The specific settings should be combined with the system's parameter values.

[0143] For example, if the voltage change rate U′ t1 Reaching or exceeding the threshold U′ th Then, the output power of the first pitch servo module 11 is gradually reduced, while the output power of the second pitch servo module 12 and the third pitch servo module 13 is gradually increased to maintain a constant total power. If the voltage change rate U′ t1 and voltage change rate U′ t2 Arriving at or exceeding the threshold U′ in sequence th Then, the output power of the first pitch servo module 11 is gradually reduced; then the output power of the second pitch servo module 12 is gradually reduced; during this process, the output power of the third pitch servo module 13 is gradually increased to maintain the total power constant. In this embodiment, "in order" means that the value of the former is always lower than that of the latter.

[0144] Similarly, at the voltage change rate U t ′3 alone or with voltage change rate U t ′1 or voltage change rate U t ′2 simultaneously reach or exceed threshold Ut h The above method is applied to the case, which is not repeated here.

[0145] This process realizes multiple insurance, improves the security and reliability of the system.

[0146] S3, set the threshold value U Dth of the voltage difference, and determine whether the voltage difference U 12 between the first bus and the third bus or the voltage difference U 13 between the second bus and the third bus exceeds the threshold value U 23 ; if yes, enable the backup power supply of the pitch servo system with the lowest bus voltage, and go to S4; if no, return to S1. Dth

[0147] For example, if the voltage difference U 12 exceeds the threshold value U Dth , compare the first bus voltage U bus1 and the second bus voltage U bus2 , if the first bus voltage U bus1 is less than the second bus voltage U bus2 , enable the first backup power supply 61, otherwise enable the second backup power supply 62.

[0148] Similarly, if the voltage difference U 13 or the voltage difference U 23 exceeds the threshold value U Dth , compare the corresponding bus voltages and enable the corresponding backup power supply, which is not repeated here.

[0149] This process enables the backup power supply to supplement the output voltage of the AC power supply and the AC / DC converter under the condition that the voltage difference between the buses gradually increases, so that each pitch servo module returns to the normal working state, and the security and reliability of the system are improved.

[0150] S4, real-time acquisition of the voltage U bat1 of the first backup power supply 61, the voltage U bat2 of the second backup power supply 62, and the voltage U bat3 of the third backup power supply 63, set the threshold value U Bth of the backup power supply, and determine whether the voltage U bat1 of the first backup power supply 61, the voltage U bat2 of the second backup power supply 62, or the voltage U bat3 of the third backup power supply 63 is lower than the threshold value U Bth ;​If yes, go to S5; if no, gradually reduce the output power of the backup power supply with the lowest voltage and gradually increase the output power of the backup power supply with the highest voltage to maintain the total power unchanged and go to S6.

[0151] For example, if the voltage U bat1 is lower than the threshold value U Bth , gradually reduce the output power of the first backup power supply 61 and gradually increase the output power of the second backup power supply 62 and the third backup power supply 63 to maintain the total power unchanged. If the voltage U bat1 and the voltage U bat2 reach or exceed the threshold value U Bth in turn, gradually reduce the output power of the first backup power supply 61; then gradually reduce the output power of the second backup power supply 62; in the process, gradually increase the output power of the third backup power supply 63 to maintain the total power unchanged.

[0152] Similarly, when the voltage U bat3 of the third backup power supply 63 alone or together with the voltage U bat1 of the first backup power supply 61 or the voltage U bat2 of the second backup power supply 62 reaches or exceeds the threshold value U Bth , the above method is used for processing, which will not be repeated here.

[0153] This process reduces the dependence on backup power supplies that are gradually losing energy, avoids the impact on the system during the energy loss process of the backup power supplies, and improves the safety and stability of the system.

[0154] S5, real-time collection of the output power P real1 of the first variable pitch servo module 11, the output power P real2 of the second variable pitch servo module 12, and the output power P real3 of the third variable pitch servo module 13, setting the output power threshold P r of the variable pitch servo module, and determining whether the output power P real1 of the first variable pitch servo module 11, the output power P real2 of the second variable pitch servo module 12, or the output power P real3 of the third variable pitch servo module 13 is lower than the output power threshold P r ; if yes, make the backup power supply with high power output at the maximum rated power, make the backup power supply with the lowest power enter the power generation mode, and go to S6; if no, make the backup power supply with high power output at the maximum rated power and make the backup power supply with the lowest power provide the minimum output power.

[0155] After entering the power generation mode, the energy of the backup power supply is gradually increased and the voltage is gradually increased by alternating current or blade rotation charging until the voltage exceeds the threshold value U BthAfter that, the backup power supply is reactivated.

[0156] For example, if the output power P real1 is lower than the output power threshold P r , the second backup power supply 62 and the third backup power supply 63 are made to output at the maximum rated power, and the first backup power supply 61 is made to enter the power generation mode. If the output power P real1 and the output power P real2 are lower than the output power threshold P r in turn, the third backup power supply 63 is made to output at the maximum rated power, the first backup power supply 61 is made to enter the power generation mode first, and then the second backup power supply 62 is made to enter the power generation mode.

[0157] Similarly, if the output power P real3 is lower than the output power threshold P real1 or the output power P real2 is lower than the output power threshold P r , the corresponding backup power supply is made to output at the maximum rated power, and the remaining backup power supplies are made to enter the power generation mode in turn.

[0158] If the output power P real1 is not lower than the output power threshold P r , the second backup power supply 62 and the third backup power supply 63 are made to output at the maximum rated power, and the first backup power supply 61 is made to provide the minimum output power.

[0159] Similarly, if the output power P real2 or the output power P real3 is not lower than the output power threshold P r , the corresponding backup power supply is made to output at the maximum rated power, and the remaining backup power supplies are made to provide the minimum output power.

[0160] This process reduces the dependence on the backup power supply with voltage attenuation when the backup power supply has voltage attenuation and all the pitch servo modules can still work normally, avoids the impact on the system during the voltage attenuation of the backup power supply, and improves the safety and stability of the system. When the backup power supply has voltage attenuation and is not sufficient to support all the pitch servo modules to work normally, the output of the backup power supply with the lowest output power is quickly cut off to make it enter the power generation mode, so as to restore power supply in the shortest time and save the entire wind turbine.

[0161] S6, judge whether the voltage difference U 12 between the first bus and the second bus, the voltage difference U 13 between the first bus and the third bus, and the voltage difference U 23 between the second bus and the third bus are lower than the threshold U DthIf yes, the current power distribution ratio is maintained; if no, the process returns to step S4.

[0162] The embodiment provides multiple problem solutions for the entire variable pitch servo system. By considering bus voltages, voltage change rates of the buses, voltage differences between the buses, backup power voltages, and variable pitch servo modules, parameters that greatly affect the system are comprehensively considered, multiple auxiliary, supplementary, and replacement schemes are formed between AC power, between backup power, and between AC power and backup power, and the safety and reliability of the system are greatly improved, and the system redundancy is low.

[0163] The above description of disclosed embodiments enables one skilled in the art to make or use the application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein can be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A wind turbine blade pitch control method, comprising at least two pitch servo modules and three motors, each pitch servo module comprising an AC / DC converter, a pitch controller, a backup power supply and at least two pitch servo units, the input of the AC / DC converter being connected to an alternating current, the pitch servo units and the backup power supply in the same pitch servo module being connected in parallel to the output of the AC / DC converter, the pitch controllers of different pitch servo modules being connected in signal, the backup power supplies of different pitch servo modules being connected in electricity, the three blades being connected to the three motors one by one, each motor being of a double-winding structure, different pitch servo units being connected to each winding, an electric energy control unit being arranged between each backup power supply and the input of the pitch servo unit; characterized in that: The method comprises the following steps: Step 1, setting bus voltage rate of change threshold , bus voltage difference threshold , backup power supply voltage threshold , and output power threshold of the pitch servo module ; Step 2, acquiring the bus voltage, voltage change rate of each bus, voltage difference between buses, voltage of each backup power supply and output power of each variable pitch servo module in real time; Step 3, judging the relationship between the voltage change rate of each bus, the voltage difference between buses, the voltage of the backup power supply and the output power of the variable pitch servo module and the respective threshold values in turn, and adjusting the output power of each module according to different relationships; the specific process is as follows: Step 3.1, judging whether the voltage change rate of each bus reaches or exceeds a threshold value If yes, step 3.2 is executed; Step 3.2, gradually reduce the output power of the variable pitch servo module with the lowest voltage, and gradually increase the output power of the variable pitch servo module with the highest voltage; determine whether the voltage difference between the bus bars reaches or exceeds the threshold value If yes, enable the backup power supply of the variable pitch servo system with the lower bus voltage, and perform step 3.

3. Step 3.

3. Determine if the voltage of each backup power source is below a threshold If yes, perform step 3.4, otherwise, return to perform step 3.

1. Step 3.4, judging whether the output power of each variable-pitch servo module is lower than an output power threshold If yes, the backup power supply with high power outputs at the maximum rated power, and the backup power supply with low power enters the power generation mode; otherwise, the backup power supply with high power outputs at the maximum rated power, and the backup power supply with low power provides the minimum output power. Step 3.5, determine if the voltage difference between each bus is below a threshold ; if so, maintain the current power distribution ratio; Otherwise, return to step 3.3; Step 4, repeating steps 2 to 3 to keep the output power of each module of the system balanced.

2. The wind power paddle variable paddle method according to claim 1, characterized in that: The variable pitch servo module includes two, each variable pitch servo module includes three variable pitch servo units, the three variable pitch servo units in the first variable pitch servo module are connected to one winding of the three motors one by one, and the three variable pitch servo units in the second variable pitch servo module are connected to another winding of the three motors one by one.

3. The wind power paddle variable paddle method according to claim 1, characterized in that: The variable pitch servo module includes three, each variable pitch servo module includes two variable pitch servo units, and two windings on each motor are connected to one variable pitch servo unit.

4. The wind power paddle variable paddle method according to claim 3, characterized in that: The variable pitch servo units connected on the same motor belong to the same variable pitch servo module.

5. The wind power paddle variable paddle method according to claim 1, characterized in that: The backup power supply and the alternating current are connected in series with the charger.

6. The wind power paddle variable paddle method according to claim 1, characterized in that: The power control unit includes but is not limited to a diode or a bidirectional DC / DC converter connected in series between the backup power supply and the input end of the variable pitch servo unit.

7. The wind power paddle variable paddle method according to claim 1, characterized in that: After the backup power supply enters the power generation mode, the backup power supply is charged through alternating current or blade rotation.

8. The wind power paddle variable paddle method according to claim 1, characterized in that: If the voltage change rate of more than one variable pitch servo module exceeds the corresponding threshold value, the output power of the corresponding module is gradually reduced in the order of time in turn, and the output power of the former is always lower than that of the latter.

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