A controlled method and controlled circuit for backup power supply of wind turbine generator set

Abstract

The present invention discloses a controlled method for a backup power supply of a wind turbine generator set and a controlled circuit thereof. When the grid voltage is normally supplied, the backup power supply voltage of the wind turbine generator set is maintained within a preset voltage range to ensure that the backup power supply always maintains sufficient energy required to complete the blade feathering process; when the grid is powered off, after the blade feathering is completed, if it is monitored that the grid is still in a power-off state, deep discharge protection is performed on the backup power supply to avoid damage to the backup power supply due to exhaustion of power after continuous discharge; the present invention realizes the predicted automatic controlled closed-loop operation of the backup power supply of the wind turbine generator set through the connection timing between the circuits, and no additional manual operation and maintenance intervention is required after the grid power is restored, thereby improving the reliability of the wind turbine generator set, reducing the downtime of the unit, and significantly reducing the operation and maintenance cost of the wind turbine generator set.

Description

Technical Field

[0001] The invention belongs to the field of wind power generation, and in particular relates to a controlled method and a controlled circuit of a backup power supply of a wind power generator set. Background Art

[0002] In recent years, with the widespread popularity of new energy vehicles and intelligent equipment, social electricity consumption has grown rapidly, and clean energy has developed rapidly. The annual growth rate of global renewable energy utilization has reached 25%. The utilization of renewable energy will be dominated by the power industry, and the proportion of non-hydro renewable energy generation will double. Wind power generation is the most mature renewable energy generation technology besides hydropower generation, and its installed capacity accounts for the vast majority of the total installed capacity of renewable energy generation.

[0003] To be more specific, a wind power source is composed of a wind turbine generator set, a tower supporting the generator set, a battery charge controller, an inverter, a load unloader, a grid-connected controller, a battery pack, etc.; a wind turbine generator set includes a wind rotor and a generator; the wind rotor contains blades, a hub, reinforcements, etc.; it has functions such as the blades rotating under wind power to generate electricity and the generator head rotating. As the power of a single wind turbine generator set increases, higher requirements are placed on the safe and reliable operation of the generator set. One very important aspect is that the blades of the wind turbine generator set become longer and the windward area becomes larger, so as to make fuller use of wind energy and increase the power generation of the unit. At the same time, it also brings greater stress to the unit. When the wind speed is too high or a typhoon is coming, the blades need to be quickly and reliably feathered to reduce the windward surface of the blades to ensure the safety of the unit in strong winds. Therefore, at any time, the reliable feathering function of the unit becomes particularly important. Generally, the variable pitch system of a wind turbine generator set is equipped with a backup power supply (battery or supercapacitor) for emergency feathering function. However, in actual applications, it is found that the backup safety power supply (battery) is at risk of damage due to long-term deep discharge, and it is actually impossible to achieve the goal of fast and reliable pulping at any time when needed.

[0004] Therefore, the applicant hopes to seek technical solutions to improve the above technical problems. Summary of the invention

[0005] In view of this, the purpose of the present invention is to propose a controlled method and a controlled circuit for a backup power supply of a wind turbine generator set. Through the connection timing between the circuits, the expected automatic controlled closed-loop operation of the backup power supply of the wind turbine generator set is realized. No additional manual operation and maintenance intervention is required after the power grid is restored. The reliability of the wind turbine generator set is improved, the downtime of the unit is reduced, and the operation and maintenance cost of the wind turbine generator set is significantly reduced.

[0006] To this end, the technical solution adopted in the present invention is as follows: A method for controlling a backup power supply of a wind turbine generator set. When the grid voltage is normally supplied, the backup power supply voltage of the wind turbine generator set is maintained within a preset voltage range to ensure that the backup power supply always maintains sufficient energy required to complete a blade feathering process. When the grid is powered off, after the blade feathering is completed, if it is monitored that the grid is still in a power-off state, deep discharge protection is performed on the backup power supply to avoid damage to the backup power supply due to exhaustion of power after continuous discharge.

[0007] Preferably, when the grid voltage is supplying power normally, after the blades are aligned, if it is monitored that the backup power supply voltage is less than a preset minimum warning voltage value, the backup power supply is charged by a constant current charging method until it is monitored that the backup power supply voltage reaches a preset maximum voltage limit, then charging is stopped to ensure that it is not overcharged.

[0008] Preferably, the deep discharge protection includes: cutting off the load of the backup power supply to prevent the backup power supply from continuously discharging.

[0009] Preferably, when normal power supply is restored after a power outage in the power grid, the backup power supply automatically restores the controlled state when the power grid voltage is normally powered: the backup power supply voltage of the wind turbine generator set is maintained within a preset voltage range, ensuring that the backup power supply always maintains sufficient energy to complete the blade feathering process.

[0010] Preferably, a controlled circuit used in the controlled method of the backup power supply of a wind turbine generator set described above comprises a grid power supply detection circuit, a flyback power supply single-trigger start-up circuit, a high-voltage flyback switch power supply circuit, a BOOST circuit, an LLC power supply circuit and a constant current charging power supply circuit, wherein: The grid power supply detection circuit is connected to the three-phase voltage of the grid and is used to monitor the grid voltage state in real time, and the output end of the grid power supply detection circuit is connected to the flyback power supply single trigger start circuit; The flyback power supply single-shot trigger start-up circuit is connected between the positive pole of the DC bus voltage and the 0 voltage reference point, and is connected to a RUN signal indicating the working state of the LLC power supply circuit; It should be noted that the single-trigger starting circuit of the flyback power supply described in the present application is used to stop the operation of the flyback power supply circuit, stop the output, and put the flyback power supply starting circuit into a reset state; on the contrary, an invalid RUN signal will unlock the flyback power supply circuit, allowing it to enter a ready-to-work state, and start working after the next normal input of the three-phase grid voltage.

[0011] The high-voltage flyback switching power supply circuit is connected between the positive pole of the DC bus voltage and the 0 voltage reference point, and its output end is connected to the LLC power supply circuit; It should be noted that the high-voltage flyback switching power supply circuit described in the present application is used to provide the necessary voltage to the LLC power supply circuit so that the LLC power supply circuit can operate normally.

[0012] The BOOST circuit is connected between the positive pole of the DC bus voltage and the LLC power circuit, and the RUN signal is connected to the control end of the BOOST circuit. When the LLC power circuit is started and operates normally, the BOOST circuit is self-locked to maintain the circuit voltage output of the LLC power circuit to ensure its continuous operation; It should be noted that the BOOST circuit described in this application is used to provide a stable DC output voltage at its output end when the three-phase voltage of the power grid fluctuates over a wide range, and the LLC power supply circuit described in this application is mainly used to isolate and convert high voltage and high efficiency into the low voltage required for the operation of electronic circuits; The constant current charging power supply circuit is connected between the positive pole of the DC bus voltage and the backup power supply, and a DSP circuit is provided between the constant current charging power supply circuit and the Shut down control pin of the LLC power supply circuit, and the DSP circuit selectively sends a Shut down signal to the LLC power supply circuit to selectively shut down the voltage output of the LLC power supply circuit; The backup power supply is connected between the positive pole of the DC bus voltage and the LLC power supply circuit.

[0013] Preferably, when the voltage output of the LLC power supply circuit is turned off, the RUN signal will disappear accordingly; wherein, when the RUN signal disappears, the BOOST circuit is automatically shut down from output, and at the same time, the flyback power supply single-shot start-up circuit is reset, so that the output of the flyback power supply single-shot start-up circuit is turned off.

[0014] Preferably, the grid power supply detection circuit includes a current limiting resistor and an optocoupler; wherein the three-phase voltage of the grid is respectively connected to the positive ends of the first transistor, the second transistor, and the third transistor, and the negative ends of the first transistor, the second transistor, and the third transistor are connected in parallel and connected to the current limiting resistor; the other end of the current limiting resistor is connected to the positive electrode on the light-emitting diode side of the optocoupler, and the negative electrode on the light-emitting diode side of the optocoupler is connected to the negative electrode of the voltage, and the output end of the optocoupler is connected to the single-trigger starting circuit of the flyback power supply.

[0015] Preferably, the flyback power supply single-trigger startup circuit comprises a first resistor, a first diode, a first capacitor, a second resistor, and a first field effect transistor; wherein, The first resistor is connected between the positive electrode of the DC bus voltage and the cathode of the first diode, and the anode of the first diode is connected to a 0 voltage reference point; The first capacitor, the second resistor and the first diode are respectively connected in parallel; The drain of the first field effect transistor is connected to the cathode of the first diode, and a third resistor is provided between its insulating gate and its drain, and its source is connected to the high-voltage flyback switch power supply circuit; The drain of the first field effect transistor is connected to the source of the second field effect transistor, the drain of the second field effect transistor is connected to the second capacitor and the fourth resistor in sequence, and the other end of the fourth resistor is connected to the 0 voltage reference point; at the same time, the drain of the second field effect transistor is connected to the C pole on the transistor side of the optocoupler through the fifth resistor, and the positive electrode of the second capacitor is connected to the E pole on the transistor side of the optocoupler through the sixth resistor; The RUN signal is connected to the insulated gate of the second field effect transistor.

[0016] Preferably, the high-voltage flyback switching power supply circuit comprises a seventh resistor, a second diode and a third diode connected in sequence, and a switching power supply chip, wherein: The seventh resistor is connected to the positive pole of the DC bus voltage, the positive pole of the third diode is connected to the 0 voltage reference point, and the cathode is connected to the anode of the second diode; The cathode of the third diode is respectively connected to the drain of the third field effect tube and the insulated gate of the fourth field effect tube, the source of the third field effect tube is connected to the anode of the third diode, and the insulated gate is connected to the source of the first field effect tube; The drain of the fourth field effect transistor is connected to one end of the primary side of the high-frequency transformer; the other end of the primary side of the high-frequency transformer is connected to the positive pole of the DC bus voltage; a fourth diode is connected in parallel between the source of the fourth field effect transistor and its insulated gate; The source of the fourth field effect tube is connected to the drain pin of the internal integrated switch tube in the switching power supply chip; The output pin of the switching power supply chip is connected to the LLC power supply circuit.

[0017] Preferably, a fifth field effect transistor is provided between the LLC power supply circuit and the RUN signal output terminal, wherein the insulated gate of the fifth field effect transistor is connected to the output terminal of the voltage-stabilizing diode, the drain of the fifth field effect transistor is connected to the LLC power supply circuit, and is connected to the input terminal of the voltage-stabilizing diode through a resistor-capacitor network, and the source of the fifth field effect transistor is connected to the positive electrode of the light-emitting diode, and the negative electrode of the light-emitting diode is connected to the RUN signal output terminal; wherein the resistor-capacitor network includes an eighth resistor and a third capacitor connected between the drain of the fifth field effect transistor and the input terminal of the voltage-stabilizing diode, and the connection point between the eighth resistor and the third capacitor is connected to the insulated gate of the fifth field effect transistor , the connection point between the third capacitor and the input end of the voltage-stabilizing diode is connected to the drain of the fifth field-effect transistor through the ninth resistor; in actual operation, when the LLC power supply circuit is unstable, the voltage at the drain of the fifth field-effect transistor Q5 is unstable, the fifth field-effect transistor Q5 will not be turned on, and the RUN signal is invalid. Only when the LLC power supply circuit is stably working, the fifth field-effect transistor Q5 will be turned on, and the RUN signal is valid. It belongs to the reliability circuit structure design. The light-emitting diode H1 is used to indicate the working status of the LLC power supply circuit. Specifically, when the light-emitting diode H1 is on, it represents normal operation. Otherwise, the light is off, which represents abnormal operation or non-operation.

[0018] Preferably, a ninth resistor is provided between the cathode of the light emitting diode and the RUN signal output terminal.

[0019] Preferably, a pull-down resistor is provided between the cathode of the light-emitting diode and the ninth resistor, and the other end of the pull-down resistor is connected to the 0 voltage reference point; preferably, a fourth capacitor is provided between the ninth resistor and the RUN signal output end, and the other end of the fourth capacitor is connected to the 0 voltage reference point.

[0020] Preferably, a fifth diode is provided between one end of the backup power supply and the positive pole of the DC bus voltage, the positive pole of the fifth diode is connected to the backup power supply, and the negative pole thereof is connected to the positive pole of the DC bus voltage; a sixth diode is provided between the other end of the backup power supply and the 0 voltage reference point, the positive pole of the sixth diode is connected to the 0 voltage reference point, and the negative pole thereof is connected to the backup power supply.

[0021] It should be noted that the BOOST circuit, LLC power supply circuit, DSP circuit and constant current charging power supply circuit involved in the present invention are common knowledge to those skilled in the art. This part is not an independent innovative content of the present application. The present application does not impose any special restrictions on the specific circuit components and connection schemes used therein. In order to save space for the description, the components used in the circuit will not be specifically expanded.

[0022] The present invention proposes a controlled method for a backup power supply of a wind turbine generator set, thereby avoiding the risk of damage to the backup power supply (that is, the battery) due to long-term deep discharge; at the same time, blade feathering operation can be achieved in an emergency, thereby improving the safety of the wind turbine generator set; the present invention also proposes a controlled circuit for a specific backup power supply of a wind turbine generator set, which uses a small number of components to form each functional circuit, and through the connection timing between each circuit, the predicted automatic controlled closed-loop operation of the backup power supply of the wind turbine generator set is achieved, and no additional manual operation and maintenance intervention is required after the power grid is restored after a power outage, thereby improving the reliability of the wind turbine generator set, reducing the downtime of the unit, and significantly reducing the operation and maintenance cost of the wind turbine generator set. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the controlled circuit connection structure of the backup power supply of the wind turbine generator set in a specific implementation mode of the present application; Figure 2 It is a schematic diagram of the connection structure of the power grid power supply detection circuit A in the specific implementation mode of the present application; Figure 3 It is a schematic diagram of the connection structure of a flyback power supply single-trigger startup circuit B (referred to as a "flyback power supply circuit") in a specific implementation manner of the present application; Figure 4 It is a schematic diagram of the connection structure of a high-voltage flyback switching power supply circuit C in a specific implementation mode of the present application; Figure 5 It is a schematic diagram of the connection structure of circuit D between the LLC power supply circuit and the RUN signal output terminal in a specific implementation manner of the present application. DETAILED DESCRIPTION

[0024] An embodiment of the present invention discloses a controlled method for a backup power supply of a wind turbine generator set. When the grid voltage is normally supplied, the backup power supply voltage of the wind turbine generator set is maintained within a preset voltage range to ensure that the backup power supply always maintains sufficient energy required to complete the blade feathering process. When the grid is powered off, after the blade feathering is completed, if it is monitored that the grid is still in a power-off state, deep discharge protection is performed on the backup power supply to avoid damage to the backup power supply due to exhaustion of power after continuous discharge.

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] See also Figure 1 Combined with Figure 2 , Figure 3 , Figure 4 and Figure 5 As shown, this embodiment provides a controlled circuit based on a backup power supply of a wind turbine generator set, including a power grid power supply detection circuit ( Figure 1 Marked as "A"), flyback power supply one-shot start-up circuit ( Figure 1 Marked as "B"), high voltage flyback switching power supply circuit ( Figure 1 Marked as "C"), BOOST circuit, LLC power supply circuit and constant current charging power supply circuit, wherein the grid power supply detection circuit is connected to the three-phase voltage of the grid for real-time monitoring of the grid voltage state, and the output end of the grid power supply detection circuit is connected to the flyback power supply single trigger starting circuit; the flyback power supply single trigger starting circuit is connected between the DC bus voltage positive pole UB+ and the 0 voltage reference point GND_Primary, and it is connected to the RUN signal indicating the working state of the LLC power supply circuit; the flyback power supply single trigger starting circuit of this embodiment is used to stop the flyback power supply circuit from working, stop the output, and put the flyback power supply starting circuit into a reset state; on the contrary, an invalid RUN signal will unlock the flyback power supply circuit, allowing it to enter a ready-to-work state, and start working after the next three-phase grid voltage is normally input.

[0027] In this embodiment, the high-voltage flyback switching power supply circuit is connected between the DC bus voltage positive electrode UB+ and the 0 voltage reference point GND_Primary, and its output end is connected to the LLC power supply circuit; the high-voltage flyback switching power supply circuit of this embodiment is used to provide the necessary voltage to the LLC power supply circuit so that the LLC power supply circuit can work normally; In this embodiment, the BOOST circuit is connected between the positive electrode UB+ of the DC bus voltage and the LLC power supply circuit, and the RUN signal is connected to the control end of the BOOST circuit. When the LLC power supply circuit is started and operates normally, the BOOST circuit is self-locked to maintain the circuit voltage output of the LLC power supply circuit to ensure its continuous operation; the BOOST circuit of this embodiment is used when the three-phase voltage of the power grid fluctuates over a wide range, and its output end can provide a stable DC output voltage (specifically preferably, in this embodiment, the DC output voltage is 740V). The LLC power supply circuit of this embodiment is mainly used to convert high-voltage and high-efficiency isolation into a DC low voltage required for the operation of the electronic circuit (specifically preferably, in this embodiment, the DC low voltage required for the operation of the electronic circuit is 24V); In this embodiment, the constant current charging power supply circuit is connected between the positive pole of the DC bus voltage UB+ and the backup power supply, and a DSP circuit is provided between the constant current charging power supply circuit and the Shut down control pin of the LLC power supply circuit. The DSP circuit selectively sends a Shut down signal to the LLC power supply circuit to selectively shut down the voltage output of the LLC power supply circuit; the backup power supply is connected between the positive pole of the DC bus voltage UB+ and the LLC power supply circuit.

[0028] Preferably, in this embodiment, when the voltage output of the LLC power supply circuit is turned off, the RUN signal will disappear; wherein, when the RUN signal disappears, the BOOST circuit is automatically shut down and the flyback power supply single-shot start-up circuit is reset, so that the output of the flyback power supply single-shot start-up circuit is turned off.

[0029] Preferably, in this embodiment, the grid power supply detection circuit includes a current limiting resistor Rx and an optocoupler OK1; wherein the three-phase voltages L1, L2, and L3 of the grid are respectively connected to the positive ends of the first transistor V1, the second transistor V2, and the third transistor V3, and the negative ends of the first transistor V1, the second transistor V2, and the third transistor V3 are connected in parallel and then connected to the current limiting resistor Rx; the other end of the current limiting resistor Rx is connected to the positive electrode on the light-emitting diode side of the optocoupler OK1, and the negative electrode on the light-emitting diode side of the optocoupler OK1 is connected to the voltage negative electrode -UB, and the output end of the optocoupler OK1 is connected to the flyback power supply single trigger starting circuit.

[0030] Preferably, in this embodiment, the flyback power supply single-shot trigger start-up circuit includes a first resistor Ry, a first diode D9, a first capacitor C2, a second resistor R11, and a first field effect transistor Q2; wherein the first resistor Ry is connected between the DC bus voltage positive electrode UB+ and the cathode of the first diode D9, and the anode of the first diode D9 is connected to the 0 voltage reference point GND_Primary; the first capacitor C2, the second resistor R11 and the first diode D9 are connected in parallel respectively; the drain of the first field effect transistor Q2 is connected to the cathode of the first diode D9, and a third gate is provided between the insulated gate and the drain thereof. Resistor R5, whose source is connected to the high-voltage flyback switching power supply circuit; the drain of the first field effect transistor Q2 is connected to the source of the second field effect transistor Q4, the drain of the second field effect transistor Q4 is connected to the second capacitor C6 and the fourth resistor R23 in sequence, and the other end of the fourth resistor R23 is connected to the 0 voltage reference point GND_Primary; at the same time, the drain of the second field effect transistor Q4 is connected to the C pole on the transistor side of the optical coupler OK1 through the fifth resistor R17, and the positive electrode of the second capacitor C6 is connected to the E pole on the transistor side of the optical coupler OK1 through the sixth resistor R20; the RUN signal is connected to the insulated gate of the second field effect transistor Q4.

[0031] Preferably, in this embodiment, the high-voltage flyback switching power supply circuit includes a seventh resistor R2, a second diode D2 and a third diode D3 connected in sequence, and a switching power supply chip U1, wherein the seventh resistor R2 is connected to the DC bus voltage positive electrode UB+, the positive electrode of the third diode D3 is connected to the 0 voltage reference point GND_Primary, and its cathode is connected to the anode of the second diode D2; the cathode of the third diode D3 is respectively connected to the drain of the third field effect transistor Q3 and the insulated gate of the fourth field effect transistor Q1, and the source of the third field effect transistor Q3 is connected to the insulated gate of the fourth field effect transistor Q1. The anode of the fourth field effect transistor Q1 is connected to the anode of the third diode D3, and its insulated gate is connected to the source of the first field effect transistor Q2; the drain of the fourth field effect transistor Q1 is connected to one end of the primary side of the high-frequency transformer T1; the other end of the primary side of the high-frequency transformer T1 is connected to the positive electrode of the DC bus voltage UB+; the fourth diode D4 is connected in parallel between the source of the fourth field effect transistor Q1 and its insulated gate; the source of the fourth field effect transistor Q1 is connected to the drain pin of the internal integrated switch tube in the switching power supply chip U1; the output pin of the switching power supply chip U1 is connected to the LLC power supply circuit.

[0032] Preferably, in this embodiment, please further refer to Figure 5 The circuit between the LLC power supply circuit and the RUN signal output terminal shown in the figure ( Figure 1 The fifth field effect transistor Q5 is provided between the LLC power supply circuit and the RUN signal output terminal, wherein the insulated gate of the fifth field effect transistor Q5 is connected to the cathode of the output terminal of the voltage zener diode U2, the drain of the fifth field effect transistor Q5 is connected to the LLC power supply circuit, and is connected to the input terminal of the voltage zener diode U2 through the resistor-capacitor network, and the source of the fifth field effect transistor Q5 is connected to the anode of the light-emitting diode H1, and the cathode of the light-emitting diode H1 is connected to the RUN signal output terminal; wherein the resistor-capacitor network includes an eighth resistor R24 ​​and a third capacitor C8 connected between the drain of the fifth field effect transistor Q5 and the input terminal of the voltage zener diode U2, and the connection point between the eighth resistor R24 ​​and the third capacitor C8 is connected to the fifth field effect transistor Q5. The insulated gate of Q5, the connection point between the third capacitor C8 and the input end of the voltage-stabilizing diode U2 is connected to the drain of the fifth field-effect transistor Q5 through the ninth resistor R25; in actual operation, when the LLC power supply circuit is unstable, the voltage at the drain of the fifth field-effect transistor Q5 is unstable, the fifth field-effect transistor Q5 will not be turned on, and the RUN signal is invalid. Only when the LLC power supply circuit is working stably, the fifth field-effect transistor Q5 will be turned on and the RUN signal will be valid. This is a reliability circuit structure design. The light-emitting diode H1 is used to indicate the working status of the LLC power supply circuit. Specifically, when the light-emitting diode H1 is on, it represents normal operation. Otherwise, the light is off, which represents abnormal operation or non-operation.

[0033] Further preferably, in the present embodiment, a ninth resistor R18 is provided between the cathode of the light-emitting diode H1 and the RUN signal output terminal; a pull-down resistor R22 is provided between the cathode of the light-emitting diode H1 and the ninth resistor R18, and the other end of the pull-down resistor R22 is connected to the 0 voltage reference point GND_Primary; preferably, a fourth capacitor C7 is provided between the ninth resistor R18 and the RUN signal output terminal, and the other end of the fourth capacitor C7 is connected to the 0 voltage reference point GND_Primary.

[0034] Further preferably, in this embodiment, a fifth diode D1 is provided between one end of the backup power supply and the positive pole of the DC bus voltage UB+, the positive pole of the fifth diode D1 is connected to the backup power supply, and the negative pole thereof is connected to the positive pole of the DC bus voltage UB+; a sixth diode D10 is provided between the other end of the backup power supply and the 0 voltage reference point GND_Primary, the positive pole of the sixth diode D10 is connected to the 0 voltage reference point GND_Primary, and the negative pole thereof is connected to the backup power supply.

[0035] Preferably, the present embodiment also provides a method for controlling a backup power supply of a wind turbine generator set, using the controlled circuit of the backup power supply of the wind turbine generator set according to the above embodiment, when the grid voltage is normally supplied, the backup power supply voltage of the wind turbine generator set is maintained within a preset voltage range to ensure that the backup power supply always maintains sufficient energy to complete the blade trimming process; when the grid is powered off, after the blade trimming is completed, if it is monitored that the grid is still in a power-off state, the backup power supply is deeply discharged for protection to avoid damage to the backup power supply due to exhaustion of power after continuous discharge.

[0036] Preferably, in this embodiment, when the grid voltage is normally supplied, after the blades are aligned, if the backup power supply voltage is monitored to be less than the preset minimum warning voltage, the backup power supply is charged by a constant current charging method until the backup power supply voltage reaches the preset maximum voltage limit, and then charging is stopped to ensure that it is not overcharged; Preferably, in this embodiment, the deep discharge protection includes: cutting off the load of the backup power supply to avoid continuous discharge of the backup power supply; Preferably, in this embodiment, when normal power supply is restored after a power outage in the power grid, the backup power supply automatically restores the controlled state when the power grid voltage is normally powered: the backup power supply voltage of the wind turbine is maintained within a preset voltage range, ensuring that the backup power supply always maintains sufficient energy to complete the blade feathering process.

[0037] In combination with the above implementation scheme of this embodiment, the following working process of this embodiment is further described: ① When the input voltage of the three-phase voltage L1, L2, and L3 of the power grid is normal (i.e., normal power supply), the light-emitting diode at the input end of the optocoupler OK1 lights up, controlling its output end to be turned on, triggering the flyback power supply circuit (i.e., the "flyback power supply single trigger start circuit" described in the previous text of this application") to start working; when the flyback power supply circuit works normally, its output voltage is connected to the LLC power supply circuit, and the LLC power supply circuit obtains the control voltage and starts working. After the LLC power supply circuit is started, it will synchronously trigger the BOOST circuit to start working. The LLC power supply circuit starts to have an output voltage. After the output voltage stabilizes, the RUN signal becomes valid. The valid RUN signal can maintain the stable operation of the BOOST circuit and the LLC power supply circuit, and at the same time stop the output of the flyback power supply circuit and reset the above-mentioned flyback power supply circuit. At this time, the operation of the BOOST circuit and the LLC power supply circuit is only related to the positive electrode UB+ of the DC bus voltage; thereby achieving: if the backup power supply voltage is detected to be lower than the preset minimum warning voltage, the backup power supply is charged by a constant current charging method until the backup power supply voltage is detected to reach the preset maximum voltage limit, then the charging is stopped to ensure that it is not overcharged. ② When the input voltage of the three-phase voltage L1, L2, L3 of the power grid is cut off, the backup power supply (i.e. Figure 1 The battery shown in the figure) will be automatically connected to the DC bus voltage positive electrode UB+, and the driver of the wind turbine generator set will complete safety operations such as blade feathering under the logic preset by its DSP program. After all the preset safety operations are completed, if it is detected that the power grid is still in a power-off state, the backup power supply will be deeply discharged for protection: the DSP will output a Shut down signal, and the LLC power supply circuit will stop outputting voltage after receiving a valid Shut down signal. At this time, the RUN signal will become invalid, and the BOOST circuit will also stop working after receiving an invalid RUN signal. The driver of the entire wind turbine generator set enters a stopped working state, consuming very little energy, thereby making the load of the backup power supply very small (equivalent to cutting off the load of the backup power supply), avoiding continuous discharge of the backup power supply and preventing it from being damaged due to maintaining a deep discharge state for a long time; at the same time, the invalid RUN signal will unlock the flyback power supply circuit, allowing it to jump out of the reset state and enter a ready-to-work state.

[0038] ③ When the input voltage of the three-phase voltage L1, L2, L3 of the power grid is powered on normally again, that is, when the normal power supply is restored, the working condition of the controlled circuit of this embodiment will jump to ①, and will work in a cycle again according to the above logic of ①, ②, ③.

[0039] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0040] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for controlling a backup power supply of a wind turbine generator set, characterized in that: When the grid voltage is supplying power normally, the backup power supply voltage of the wind turbine generator set is maintained within a preset voltage range to ensure that the backup power supply always maintains sufficient energy to complete the blade trimming process; when the grid is powered off, after the blade trimming is completed, if it is monitored that the grid is still in a power-off state, the backup power supply is deep-discharged for protection to avoid damage to the backup power supply due to exhaustion of power after continuous discharge.

2. The method for controlling the backup power supply of a wind turbine generator set according to claim 1, characterized in that: When the grid voltage is supplying power normally, after the blades are aligned, if it is monitored that the backup power supply voltage is lower than the preset minimum warning voltage value, the backup power supply is charged by a constant current charging method until it is monitored that the backup power supply voltage reaches the preset maximum voltage limit, then the charging is stopped to ensure that it is not overcharged.

3. The method for controlling the backup power supply of a wind turbine generator set according to claim 1, characterized in that: The deep discharge protection includes: cutting off the load of the backup power supply to prevent the backup power supply from continuously discharging.

4. The method for controlling a backup power supply of a wind turbine generator set according to claim 1, characterized in that: When the grid resumes normal power supply after a power outage, the backup power supply automatically resumes the controlled state when the grid voltage is normally powered: the backup power supply voltage of the wind turbine generator set is maintained within a preset voltage range to ensure that the backup power supply always maintains sufficient energy to complete the blade feathering process.

5. A controlled circuit used in the method for controlling a backup power supply of a wind turbine generator set according to any one of claims 1 to 4, characterized in that: It includes a grid power supply detection circuit, a flyback power supply single trigger start circuit, a high-voltage flyback switching power supply circuit, a BOOST circuit, an LLC power supply circuit and a constant current charging power supply circuit, among which: The grid power supply detection circuit is connected to the three-phase voltage of the grid and is used to monitor the grid voltage state in real time, and the output end of the grid power supply detection circuit is connected to the flyback power supply single trigger start circuit; The flyback power supply single-shot trigger startup circuit is connected between the DC bus voltage positive electrode (UB+) and the 0 voltage reference point (GND_Primary), and is connected to a RUN signal indicating the working state of the LLC power supply circuit; The high-voltage flyback switching power supply circuit is connected between the DC bus voltage positive electrode (UB+) and the 0 voltage reference point (GND_Primary), and its output end is connected to the LLC power supply circuit; The BOOST circuit is connected between the positive pole of the DC bus voltage (UB+) and the LLC power circuit, and the RUN signal is connected to the control end of the BOOST circuit. When the LLC power circuit is started and operates normally, the BOOST circuit is self-locked to maintain the circuit voltage output of the LLC power circuit to ensure its continuous operation; The constant current charging power supply circuit is connected between the positive pole of the DC bus voltage (UB+) and the backup power supply, and a DSP circuit is provided between the constant current charging power supply circuit and the Shut down control pin of the LLC power supply circuit. The DSP circuit selectively sends a Shut down signal to the LLC power supply circuit to selectively shut down the voltage output of the LLC power supply circuit. The backup power supply is connected between the positive pole (UB+) of the DC bus voltage and the LLC power supply circuit.

6. The controlled circuit used in the controlled method of the wind turbine generator backup power supply according to claim 5 is characterized in that: When the voltage output of the LLC power supply circuit is turned off, the RUN signal will disappear accordingly; wherein, when the RUN signal disappears, the BOOST circuit is automatically shut down, and at the same time, the flyback power supply single-shot start-up circuit is reset, so that the output of the flyback power supply single-shot start-up circuit is turned off.

7. The controlled circuit used in the controlled method of the wind turbine generator backup power supply according to claim 5 is characterized in that: The grid power supply detection circuit comprises a current limiting resistor (Rx) and an optocoupler (OK1); wherein the three-phase voltage (L1, L2, L3) of the grid is respectively connected to the positive ends of a first transistor (V1), a second transistor (V2), and a third transistor (V3); the negative ends of the first transistor (V1), the second transistor (V2), and the third transistor (V3) are connected in parallel and then connected to the current limiting resistor (Rx); the other end of the current limiting resistor (Rx) is connected to the positive electrode on the light emitting diode side of the optocoupler (OK1), and the negative electrode on the light emitting diode side of the optocoupler (OK1) is connected to the negative electrode of the voltage (-UB); and the output end of the optocoupler (OK1) is connected to the single-trigger start-up circuit of the flyback power supply.

8. The controlled circuit used in the controlled method of the wind turbine generator backup power supply according to claim 5 is characterized in that: The flyback power supply single-trigger startup circuit comprises a first resistor (Ry), a first diode (D9), a first capacitor (C2), a second resistor (R11), and a first field effect transistor (Q2); wherein, The first resistor (Ry) is connected between the positive pole (UB+) of the DC bus voltage and the cathode of the first diode (D9), and the anode of the first diode (D9) is connected to the zero voltage reference point (GND_Primary); The first capacitor (C2), the second resistor (R11) and the first diode (D9) are respectively connected in parallel; The drain of the first field effect tube (Q2) is connected to the cathode of the first diode (D9), a third resistor (R5) is provided between its insulating gate and its drain, and its source is connected to the high-voltage flyback switch power supply circuit; The drain of the first field effect tube (Q2) is connected to the source of the second field effect tube (Q4), the drain of the second field effect tube (Q4) is connected to the second capacitor (C6) and the fourth resistor (R23) in sequence, and the other end of the fourth resistor (R23) is connected to the 0 voltage reference point (GND_Primary); at the same time, the drain of the second field effect tube (Q4) is connected to the C pole on the triode side of the optical coupler (OK1) through the fifth resistor (R17), and the positive electrode of the second capacitor (C6) is connected to the E pole on the triode side of the optical coupler (OK1) through the sixth resistor (R20); The RUN signal is connected to the insulated gate of the second field effect transistor (Q4).

9. The controlled circuit used in the controlled method of the wind turbine generator backup power supply according to claim 8 is characterized in that: The high-voltage flyback switching power supply circuit comprises a seventh resistor (R2), a second diode (D2) and a third diode (D3) connected in sequence, and a switching power supply chip (U1), wherein: The seventh resistor (R2) is connected to the positive pole (UB+) of the DC bus voltage, the positive pole of the third diode (D3) is connected to the 0 voltage reference point (GND_Primary), and the cathode thereof is connected to the anode of the second diode (D2); The cathode of the third diode (D3) is respectively connected to the drain of the third field effect tube (Q3) and the insulating gate of the fourth field effect tube (Q1), the source of the third field effect tube (Q3) is connected to the anode of the third diode (D3), and its insulating gate is connected to the source of the first field effect tube (Q2); The drain of the fourth field effect transistor (Q1) is connected to one end of the primary side of the high-frequency transformer (T1); the other end of the primary side of the high-frequency transformer (T1) is connected to the positive pole (UB+) of the DC bus voltage; and a fourth diode (D4) is connected in parallel between the source of the fourth field effect transistor (Q1) and its insulated gate; The source of the fourth field effect tube (Q1) is connected to the drain pin of the internal integrated switch tube in the switching power supply chip (U1); The output pin of the switching power supply chip (U1) is connected to the LLC power supply circuit.

10. The controlled circuit used in the method for controlling the backup power supply of a wind turbine generator set according to claim 5, characterized in that: A fifth field effect transistor (Q5) is provided between the LLC power supply circuit and the RUN signal output end, wherein the insulated gate of the fifth field effect transistor (Q5) is connected to the output end (cathode) of the voltage zener diode (U2), the drain of the fifth field effect transistor (Q5) is connected to the LLC power supply circuit and is connected to the input end of the voltage zener diode (U2) through a resistor-capacitor network, and the source of the fifth field effect transistor (Q5) is connected to the positive electrode of the light-emitting diode (H1), and the negative electrode of the light-emitting diode (H1) is connected to the RUN signal output end; wherein the resistor-capacitor network comprises an eighth resistor (R24) and a third capacitor (C8) connected between the drain of the fifth field effect transistor (Q5) and the input end of the voltage zener diode (U2), and the connection point between the eighth resistor (R24) and the third capacitor (C8) is connected to the insulated gate of the fifth field effect transistor (Q5), and the connection point between the third capacitor (C8) and the input end of the voltage zener diode (U2) is connected to the drain of the fifth field effect transistor (Q5) through a ninth resistor (R25).

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