Control method and device of wind generating set, controller and storage medium

Abstract

The invention provides a control method and device of a wind generating set, a controller and a storage medium. The control method of the wind generating set comprises the following steps: monitoring whether a power grid power-down fault that a grid-connected end of the wind generating set is disconnected from a power grid occurs or not; switching the protection mode into a power grid power-down fault protection mode in response to monitoring that the power grid power-down fault occurs; in response to entering the power grid power-down fault protection mode, the wind generating set is controlled to be in a running state continuously; and controlling the wind generating set to stop in response to the fact that the power grid power failure fault protection mode is entered for the first preset duration.

Description

Technical Field

[0001] The present disclosure generally relates to the field of wind power generation technology, and more specifically, to a control method, device, controller and storage medium of a wind power generator set. Background Art

[0002] During the operation of a wind turbine (hereinafter referred to as a wind turbine), especially during high-power operation, when a power outage occurs in the grid, the energy produced by the wind turbine cannot be fed into the grid. The energy circulation will cause the voltage and frequency at the grid-connected end of the wind turbine to increase rapidly. When the wind turbine detects overfrequency or overvoltage, it will usually stop and disconnect from the grid. Summary of the invention

[0003] An exemplary embodiment of the present disclosure provides a control method, device, controller and storage medium for a wind turbine generator set, which can effectively protect the wind turbine safety when a power failure occurs in a power grid.

[0004] According to a first aspect of an embodiment of the present disclosure, a control method for a wind turbine generator set is provided, comprising: monitoring whether a grid power failure occurs in which a grid-connected end of the wind turbine generator set is disconnected from a grid; in response to monitoring the occurrence of a grid power failure, switching a protection mode to a grid power failure protection mode; in response to entering the grid power failure protection mode, controlling the wind turbine generator set to remain in operation; in response to entering the grid power failure protection mode for a first preset duration, controlling the wind turbine generator set to shut down.

[0005] Optionally, it also includes: in response to entering the power grid power failure protection mode, monitoring whether the DC bus voltage is overvoltage and whether the current of the converter is overcurrent; in response to the DC bus voltage being higher than a first voltage threshold or the current of the converter being higher than a first current threshold, controlling the wind turbine to shut down; in response to the DC bus voltage being higher than a second voltage threshold but not higher than the first voltage threshold for a continuous period reaching a second preset period, or the current of the converter being higher than a second current threshold but not higher than the first current threshold for a continuous period reaching a second preset period, controlling the wind turbine to shut down; wherein the first preset period is longer than the second preset period.

[0006] Optionally, the step of controlling the wind turbine generator set to be continuously in operation includes: controlling the grid-connected terminal voltage to be continuously at a target voltage value; and controlling the output torque of the generator to be continuously at a target torque value.

[0007] Optionally, the target voltage value is set based on the hardware voltage upper limit of the wind turbine generator set and the voltage control requirement for power grid power failure; and / or the target torque value is set based on the hardware current upper limit of the wind turbine generator set and the load reduction requirement for power grid power failure.

[0008] Optionally, the converter of the wind turbine generator set includes: a machine-side converter and a grid-side converter; wherein, the step of controlling the grid-connected voltage to be continuously at a target voltage value includes: controlling the output voltage of the grid-side converter and the reactive current output by the machine-side converter to keep the grid-connected voltage at the target voltage value; or, controlling the output voltage of the grid-side converter and the reactive current output by the grid-side converter to keep the grid-connected voltage at the target voltage value; or, controlling the output voltage of the generator stator and the reactive current output by the machine-side converter to keep the grid-connected voltage at the target voltage value; or, controlling the output voltage of the generator stator and the reactive current output by the grid-side converter to keep the grid-connected voltage at the target voltage value.

[0009] Optionally, the converter of the wind turbine generator set includes: a machine-side converter and a grid-side converter; wherein, the step of controlling the output torque of the generator to be continuously at a target torque value includes: controlling the active current output by the machine-side converter and starting the braking resistor so that the output torque of the generator is continuously at the target torque value.

[0010] Optionally, the step of controlling the wind turbine generator set to remain in operation also includes: in response to the output torque of the generator being maintained at the target torque value for a continuous period reaching a third preset period, controlling the generator to stop outputting the torque; wherein the first preset period is longer than or equal to the third preset period, and the third preset period is set based on the load reduction requirement for a power outage in the power grid.

[0011] Optionally, the step of controlling the output torque of the generator to be continuously at a target torque value includes: controlling the output torque of the generator to be continuously at the target torque value through a current converter controller.

[0012] Optionally, the step of monitoring whether a grid power failure occurs in which the grid-connected end of the wind turbine generator set is disconnected from the grid includes: determining that a grid power failure occurs in response to power being higher than a power threshold, grid-connected end current being lower than a current threshold, and grid-connected end voltage being higher than a voltage threshold.

[0013] According to a second aspect of an embodiment of the present disclosure, a control device for a wind turbine generator set is provided, including: a fault monitoring unit, configured to monitor whether a grid power failure occurs in which the grid-connected end of the wind turbine generator set is disconnected from the grid; a mode switching unit, configured to switch a protection mode to a grid power failure protection mode in response to detecting the occurrence of a grid power failure; an operation control unit, configured to control the wind turbine generator set to remain in operation in response to entering the grid power failure protection mode; and a shutdown control unit, configured to control the wind turbine generator set to shut down in response to entering the grid power failure protection mode for a first preset duration.

[0014] According to a third aspect of an embodiment of the present disclosure, there is provided a computer-readable storage medium storing a computer program, which, when executed by a processor, prompts the processor to execute the control method of the wind turbine generator set as described above.

[0015] According to a fourth aspect of an embodiment of the present disclosure, a controller of a wind turbine generator set is provided, the controller comprising: a processor; and a memory storing a computer program, wherein when the computer program is executed by the processor, the processor is prompted to execute the control method of the wind turbine generator set as described above.

[0016] According to a fifth aspect of an embodiment of the present disclosure, there is provided a computer program product, comprising a computer program, wherein when the computer program is executed by a processor, the control method of the wind turbine generator set as described above is implemented.

[0017] The control method, device, controller and storage medium of the wind turbine generator set according to the exemplary embodiment of the present disclosure can effectively reduce the risk of hardware failure of the wind turbine and effectively reduce the extreme load impact of components such as blades and towers when a power outage occurs.

[0018] In the following description, some aspects and / or advantages of the general inventive concept will be set forth, and some other aspects and / or advantages will be known through the following description or the implementation of the general inventive concept. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] These and / or other aspects and advantages of the present application will become clearer and easier to understand from the following detailed description of the embodiments of the present application in conjunction with the accompanying drawings, in which:

[0020] Figure 1 The voltage waveform diagram showing the moment of power failure of the power grid;

[0021] Figure 2 A flow chart showing a control method of a wind turbine generator system according to an exemplary embodiment of the present disclosure;

[0022] Figure 3 A schematic structural diagram of a wind turbine generator set according to an exemplary embodiment of the present disclosure is shown;

[0023] Figure 4 A flow chart showing a method for monitoring whether a power grid power failure occurs according to an exemplary embodiment of the present disclosure;

[0024] Figure 5 A flow chart showing a control method of a wind turbine generator set according to another exemplary embodiment of the present disclosure;

[0025] Figure 6 A structural block diagram of a control device for a wind turbine generator set according to an exemplary embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0026] Reference will now be made in detail to the embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like parts throughout. The embodiments will be described below with reference to the drawings in order to explain the present disclosure.

[0027] It should be noted that the terms "first", "second", etc. in the specification and claims of the present disclosure and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present disclosure described herein can be implemented in an order other than those illustrated or described herein. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present disclosure. Instead, they are merely examples of devices and methods consistent with some aspects of the present disclosure as detailed in the appended claims.

[0028] It should be noted that the phrase "at least one of the items" in the present disclosure includes three types of parallel situations: "any one of the items", "a combination of any number of the items", and "all of the items". For example, "including at least one of A and B" includes the following three parallel situations: (1) including A; (2) including B; (3) including A and B. Another example is "executing at least one of step 1 and step 2" which means the following three parallel situations: (1) executing step 1; (2) executing step 2; (3) executing step 1 and step 2.

[0029] On the one hand, the present disclosure takes into account that as the power of the wind turbine continues to increase, the diameter of the wind turbine impeller also gradually increases, and the electrical torque of the wind turbine also increases. When running under load, especially running under high-power load, an emergency stop and disconnection control method is usually adopted for power outage conditions of the power grid. However, this control method will cause a large limit load impact on the mechanical parts of the wind turbine, such as the blades and tower. The large blade root impact load or tower bottom bending moment load will cause a large safety hazard to the wind turbine, and will seriously lead to risks such as blade breakage. In order to deal with this risk, the above risks are usually avoided by strengthening the blades and tower strength, but the use of these methods will increase the cost of the wind turbine.

[0030] On the other hand, the present disclosure takes into account that during the operation of wind turbines under load, especially under high-power load, in order to avoid overlapping with the high voltage ride-through function (i.e., high voltage ride-through function), the threshold of the power grid power failure detection is usually set higher than the required range of the high voltage ride-through curve. Therefore, after the power grid fails, an overvoltage shock at the grid-connected end will inevitably occur. In severe cases, it will cause the failure of hardware such as the pitch control equipment and lightning protection. The voltage waveform at the time of power grid failure is as follows: Figure 1 shown.

[0031] In view of the problem of load impact caused by emergency shutdown and grid-connected overvoltage impact caused by power outage during wind turbine operation, the present invention proposes a wind turbine control method, which controls the wind turbine grid-connected voltage within the design target range during power outage to ensure hardware safety, and at the same time controls the wind turbine to maintain torque output for a period of time after the power outage to provide load support and reduce the extreme load impact of components such as blades and towers, thereby reducing the design cost of the wind turbine. Figures 2 to 6 Provide detailed explanation.

[0032] Figure 2 A flow chart showing a method for controlling a wind turbine generator system according to an exemplary embodiment of the present disclosure is shown.

[0033] As an exemplary embodiment, the control method of the wind turbine generator set according to the exemplary embodiment of the present disclosure may be applied to a double-fed wind turbine generator set. Figure 3 As shown, the generator stator of the doubly-fed wind turbine generator set is connected to the grid-connected end of the wind turbine generator set; the generator rotor is connected to the grid-connected end via a converter (specifically including a machine-side converter and a grid-side converter). Specifically, the generator rotor is connected to the AC end of the machine-side converter, the DC end of the machine-side converter is connected to the DC end of the grid-side converter, and the AC end of the grid-side converter is connected to the grid-connected end. The grid-connected end is connected to the power grid via a single-chassis transformer (hereinafter, also referred to as a single-chassis transformer), a switch device (for example, a drop switch) and other equipment.

[0034] Reference Figure 2 In step S101, it is monitored whether a grid power failure occurs in which the grid-connected end of the wind turbine generator set is disconnected from the grid.

[0035] It should be understood that a power grid power outage can also be described as a power grid open circuit, a power grid disconnection, a power grid voltage loss, a power grid voltage drop to zero, etc. The power grid power outage fault in the present disclosure includes a situation where the wind turbine loses the power grid voltage (i.e., loses the power supply voltage of the power grid voltage source) due to any fault or condition at the near end or the far end. For example, a power grid power outage fault may include: a remote tripping (or line open circuit) of a wind farm connected to the wind turbine, or a tripping or disconnection of the high-voltage side of a proximal single-chassis transformer connected to the wind turbine or a disconnection of the drop switch (or line open circuit), or a tripping of the low-voltage side of a single-chassis transformer (or line open circuit), resulting in a power grid voltage power outage.

[0036] As an exemplary embodiment, step S101 may include: monitoring whether a power failure of the power grid occurs based on at least one of the following operating parameters of the wind turbine generator set: wind turbine power, grid-connected current, grid-connected voltage, grid-side converter current (i.e., rotor grid-side current), and DC bus voltage. It should be understood that other signals may also be used to identify whether a power failure of the power grid occurs. For example, additional detection equipment may be added to detect a power open circuit fault of the power grid, and the detection signal may be transmitted to the wind turbine to identify a power failure of the wind turbine.

[0037] As an exemplary embodiment, step S101 may include: in response to the power being higher than a power threshold X, the grid-connected terminal current being lower than a current threshold Y, and the grid-connected terminal voltage being higher than a voltage threshold Z, determining that a grid power failure has occurred. As an example, step S101 may include: Figure 4 As an example, the power threshold X, current threshold Y, and voltage threshold Z may be set according to actual conditions and specific requirements.

[0038] For example, according to the characteristics of the doubly-fed wind turbine, the greater the wind turbine power at the moment of grid power failure, the higher the wind turbine port voltage (i.e., grid-connected terminal voltage) after the grid power failure. The design value of the power threshold X can be obtained according to the hardware boundary capability of the converter, for example, its value can be set to x%Pn. Regarding the current threshold Y, due to the grid power failure, the power output by the wind turbine cannot be fed into the grid, so the grid-connected current (i.e., grid-connected terminal current) of the wind turbine after the grid power failure is close to 0A. Considering the sampling deviation (e.g., the sampling deviation is e%), the value of the current threshold Y can be set to e%In. Regarding the voltage threshold Z, due to the grid power failure, the power generated by the wind turbine cannot be transmitted out, which will increase the grid-connected terminal voltage of the wind turbine. Therefore, after the grid power failure, the power generated by the wind turbine cannot be transmitted, and the energy accumulation causes the DC bus voltage of the wind turbine to increase, so that the grid-connected terminal voltage formed by the operation of the wind turbine increases. Considering that the voltage threshold Z needs to be decoupled from the high voltage crossing threshold, the voltage threshold Z can be set to a value higher than the upper limit of the high voltage crossing threshold, and the voltage threshold Z also needs to be lower than the hardware tolerance limit of the wind turbine. Among them, Pn represents the rated power of the fan, In represents the rated current of the fan, and Un represents the rated voltage of the fan.

[0039] According to an exemplary embodiment of the present disclosure, a method for quickly identifying a power failure of a doubly-fed wind turbine grid is designed. By simultaneously judging the power, grid voltage, and grid current, a power failure of a doubly-fed wind turbine grid can be quickly and accurately identified. The rapid identification of a power failure of a grid is conducive to the wind turbine to quickly perform corresponding control actions and improve the reliability of wind turbine operation.

[0040] In step S102, in response to monitoring that a power grid power failure occurs, the protection mode is switched to a power grid power failure protection mode.

[0041] As an example, in response to detecting that a power grid power failure occurs, the protection mode is switched from a normal power generation operation protection mode to a power grid power failure protection mode.

[0042] In step S103, in response to entering the grid power failure protection mode, the wind turbine generator set is controlled to remain in operation.

[0043] In step S104, in response to entering the grid power failure protection mode for a first preset time period, the wind turbine generator set is controlled to shut down.

[0044] Compared with the emergency stop processing method after the power grid loses power in the prior art, the present disclosure proposes to control the wind turbine to remain in operation within a first preset time after the power grid loses power. Regarding the specific operation mode of the wind turbine after the power grid loses power, as an exemplary embodiment, the step of controlling the wind turbine generator set to remain in operation may include: controlling the grid-connected voltage to remain at a target voltage value, and controlling the output torque of the generator to remain at a target torque value. Specifically, the wind turbine generator set is controlled with the control target of making the grid-connected voltage remain at the target voltage value and the output torque of the generator remain at the target torque value.

[0045] In addition, as an exemplary embodiment, the step of controlling the wind turbine generator set to be continuously in operation may also include: in response to the output torque of the generator being maintained at the target torque value for a duration reaching a third preset duration, controlling the generator to stop outputting the torque. As an example, the first preset duration t1 is longer than or equal to the third preset duration t3, that is, t1 ≥ t3. As an example, the third preset duration may be set based on the load reduction requirement for a power failure in the power grid, and the load reduction requirement for a power failure in the power grid may refer to: mechanical components such as blades and bearings, and how long the torque support needs to be maintained after the power failure in the power grid to ensure load safety. It should be understood that the first preset duration and the third preset duration may be set according to actual conditions and specific needs.

[0046] As an exemplary embodiment, the target voltage value can be set based on the upper voltage limit that the hardware of the wind turbine can withstand and the voltage control requirements for power failures in the power grid. Specifically, the setting of the target voltage value needs to consider two aspects: 1. Hardware safety: such as the safety of equipment such as variable pitch equipment and converters, that is, after the power grid is powered off, the voltage generated by the operation of the wind turbine cannot exceed the upper voltage limit that the hardware equipment of the wind turbine can withstand; 2. Control requirements: that is, the maximum voltage allowed to be output by the converter from a control perspective, which is limited by the DC bus voltage. Specifically, after the power grid is powered off, the DC bus voltage is generally maintained at U dc_grid_openAccording to the principle of space vector modulation of the converter, the line voltage peak value of the AC voltage output on the machine side and the grid side of the converter cannot be higher than the DC bus voltage value, so that the converter can be in the linear control range. Therefore, the target voltage value cannot be higher than the DC bus voltage. When the DC bus voltage range is determined, the target voltage value can be set according to the DC bus voltage value U dc_grid_open Calculate the upper limit of the target voltage value. For example, the upper limit of the target voltage value can be U dc_grid_open / √3. In addition, considering that the target voltage value needs to be decoupled from the high voltage ride-through threshold, the target voltage value can be higher than the upper limit of the high voltage ride-through threshold. For example, the target voltage value can be set to a%Un, where Un represents the rated voltage of the wind turbine.

[0047] As an exemplary embodiment, the target torque value is set based on the upper limit of the current that the hardware of the wind turbine generator can withstand and the load reduction requirement for the power grid power failure. X It can be set to b%Tn, where Tn represents the rated torque of the fan.

[0048] On the first aspect, the present disclosure proposes to control the grid-connected terminal voltage of the wind turbine at a target voltage value after the power grid is disconnected, so as to avoid the risk of overvoltage failure of the hardware of the wind turbine; on the second aspect, the present disclosure proposes to control the generator to continuously output a torque of controllable amplitude within a set time after the power grid is disconnected, and the electromagnetic torque output by the generator can balance the aerodynamic torque of the impeller, thereby being able to quickly reduce the speed of the wind turbine and reduce the load of the wind turbine. If the emergency stop process is performed according to the existing technology, the generator torque will immediately drop to 0 after the power grid is disconnected, that is, the generator has no electromagnetic torque and cannot balance the aerodynamic torque of the impeller. The impeller speed will accelerate, causing the blades to bear excessive load, and in severe cases, the blades will break.

[0049] With respect to the first aspect, as an exemplary embodiment, the step of controlling the grid-connected voltage to be continuously at a target voltage value may include: controlling the output voltage of the grid-side converter (i.e., the rotor grid-side voltage) and the reactive current output by the machine-side converter to keep the grid-connected voltage at the target voltage value; or, controlling the output voltage of the grid-side converter and the reactive current output by the grid-side converter (requiring a larger power module capacity of the grid-side converter) to keep the grid-connected voltage at the target voltage value; or, controlling the output voltage of the generator stator (the stator is connected to the grid-side converter, so they are the same voltage) and the reactive current output by the machine-side converter to keep the grid-connected voltage at the target voltage value; or, controlling the output voltage of the generator stator and the reactive current output by the grid-side converter to keep the grid-connected voltage at the target voltage value.

[0050] Regarding controlling the output voltage of the grid-side converter, it can be specifically controlled by controlling the modulation voltage of the grid-side converter (i.e., the working voltage applied to the IGBT). As an example, the modulation voltage of the grid-side converter can be set to a constant value (i.e., always set to a target voltage value). As another example, the modulation voltage can be determined by tracking the target voltage value based on the real-time value of the grid-connected voltage through a PI controller. Regarding controlling the output voltage of the generator stator, it can be specifically controlled by controlling the modulation voltage of the machine-side converter. Regarding controlling the reactive current output by the machine-side converter, it refers to controlling the reactive current applied to the doubly-fed generator by the machine-side converter. Because the grid-side converter is directly connected to the generator stator, the reactive current is emitted by the machine-side converter to achieve the modulation voltage target of the grid-side converter. As an example, the machine-side converter can be controlled by the reactive current target value. The reactive current target value is derived from the output of the grid-side modulation voltage controller. The machine-side converter can track the reactive current target value through the PI controller and emit reactive current. According to the exemplary embodiment of the present disclosure, considering that the circuit part composed of the generator rotor and the converter connected thereto is physically connected in parallel with the generator stator, the voltage at the grid-side converter or the generator stator can be controlled by controlling the voltage at the grid-side converter or the generator stator, and the voltage at the grid-side converter or the machine-side converter can be controlled by generating reactive power. That is, the above-mentioned output voltage is stabilized by controlling the output voltage of the grid-side converter (or stator) and by controlling the machine-side converter (or grid-side converter) to generate reactive current, thereby achieving the goal voltage value at the grid-side converter.

[0051] Regarding the second aspect, as an exemplary embodiment, the step of controlling the output torque of the generator to be continuously at the target torque value may include: controlling the active current output by the machine-side converter and starting the braking resistor so that the output torque of the generator is continuously at the target torque value.

[0052] As an exemplary embodiment, the step of controlling the output torque of the generator to be continuously at the target torque value may include: controlling the output torque of the generator to be continuously at the target torque value through the converter controller. As an example, in response to entering the power grid power failure protection mode, the torque control of the wind turbine can be taken over by the converter controller, mainly considering that there will be a large delay through the main control of the wind turbine (that is, the communication delay between the main control and the converter controller), the converter controller can directly set the torque set value at the target torque value, and at the same time control the braking resistor to consume the corresponding power to achieve energy consumption, that is, to achieve a constant torque control mode. As an example, the start of the braking resistor can be controlled by controlling the start voltage and stop voltage of the braking resistor. In addition, in addition to realizing the constant torque control mode after the power grid is lost by the converter alone and autonomously controlling the torque, the constant torque control can also be realized by the main control and the converter jointly, that is, in response to entering the power grid power failure protection mode, the main control sends a constant torque setting value (that is, the target torque value) to the converter controller, and the converter maintains operation and executes the target torque value sent by the main control within the first preset time length.

[0053] Compared with the control method of emergency stop and disconnection from the grid for power outage conditions in the prior art, the present disclosure proposes that after a power outage fault is detected, the wind turbine is still in operation within a first preset time period. In order to ensure the safe operation of the wind turbine during this continuous operation period, the present disclosure designs a protection logic suitable for the continuous operation period after the power outage of the grid, which not only protects the hardware safety of the wind turbine during the continuous operation period, but also considers the load reduction demand. As an exemplary embodiment, the control method of the wind turbine generator set according to the exemplary embodiment of the present disclosure may also include: in response to entering the power outage fault protection mode, monitoring whether the DC bus voltage is overvoltage and whether the current of the converter is overcurrent; in response to the DC bus voltage overvoltage or the converter current overcurrent, controlling the wind turbine generator set to shut down immediately or after the second preset time period, that is, in response to the DC bus voltage overvoltage or the converter current overcurrent, it will shut down in advance, rather than waiting to enter the power outage fault protection mode for the first preset time period before shutting down.

[0054] As an example, the wind turbine generator set can be controlled to shut down in response to the DC bus voltage being higher than the first voltage threshold or the converter current being higher than the first current threshold; the wind turbine generator set can be controlled to shut down in response to the DC bus voltage being higher than the second voltage threshold but not higher than the first voltage threshold for a second preset time, or the converter current being higher than the second current threshold but not higher than the first current threshold for a second preset time. As an example, the first preset time t1 is longer than the second preset time t2, that is, t1>t2.

[0055] As an example, the current of the converter may specifically include the current of the machine-side converter and the current of the grid-side converter. Accordingly, monitoring whether the current of the converter is overcurrent may include: monitoring whether the current of the machine-side converter is overcurrent, and monitoring whether the current of the grid-side converter is overcurrent. The first current threshold may specifically include: a first machine-side current threshold and a first grid-side current threshold. The second current threshold may specifically include: a second machine-side current threshold and a second grid-side current threshold. As an example, the wind turbine generator set may be controlled to shut down in response to the DC bus voltage being higher than the first voltage threshold, or the current of the machine-side converter being higher than the first machine-side current threshold, or the current of the grid-side converter being higher than the first grid-side current threshold. As an example, in response to the DC bus voltage being higher than the second voltage threshold but not higher than the first voltage threshold for a second preset time period, or the current of the machine-side converter being higher than the second machine-side current threshold but not higher than the first machine-side current threshold for a second preset time period, or the current of the grid-side converter being higher than the second grid-side current threshold but not higher than the first grid-side current threshold for a second preset time period, the wind turbine generator set is controlled to shut down.

[0056] It should be understood that the second preset time duration and the above threshold value may be set according to the safety and load reduction requirements of the wind turbine hardware (eg, power devices of the converter). As an example, the second preset time duration may be set to 0.1 s.

[0057] Figure 5 A flow chart showing a method for controlling a wind turbine generator system according to another exemplary embodiment of the present disclosure is shown.

[0058] Reference Figure 5 , through the wind turbine grid-connected power, grid-connected voltage and grid-connected current, the power-off status of the grid during the operation of the wind turbine can be quickly identified, and the power-off flag of the grid can be set.

[0059] According to the characteristics of a power outage during wind turbine operation, after a power outage occurs, the continuous operation state is maintained within a first preset time. Specifically, when a power outage is detected during wind turbine operation, the control mode of the grid-side converter is switched from a conventional power generation control mode to a grid-connected voltage control mode, so that the grid-connected voltage amplitude after the power outage is controlled within the target design value; and, when a power outage is detected during wind turbine operation, the control mode of the machine-side converter is switched from a conventional power generation control mode to a constant torque control mode, so that a torque with a controllable amplitude is continuously output within a set time after the power outage.

[0060] Figure 6 A structural block diagram of a control device for a wind turbine generator set according to an exemplary embodiment of the present disclosure is shown.

[0061] Reference Figure 6According to an exemplary embodiment of the present disclosure, the control device of a wind turbine generator set includes: a fault monitoring unit 101 , a mode switching unit 102 , an operation control unit 103 , and a shutdown control unit 104 .

[0062] Specifically, the fault monitoring unit 101 is configured to monitor whether a grid power failure occurs in which the grid-connected end of the wind turbine generator set is disconnected from the grid.

[0063] The mode switching unit 102 is configured to switch the protection mode to the power grid power failure protection mode in response to detecting the occurrence of a power grid power failure.

[0064] The operation control unit 103 is configured to control the wind turbine generator set to remain in operation in response to entering the grid power failure protection mode.

[0065] The shutdown control unit 104 is configured to control the wind turbine generator set to shut down in response to entering the grid power failure protection mode for a first preset time period.

[0066] As an exemplary embodiment, the shutdown control unit 104 can also be configured to: in response to entering the grid power failure fault protection mode, monitor whether the DC bus voltage is overvoltage and whether the current of the converter is overcurrent; in response to the DC bus voltage being higher than the first voltage threshold or the current of the converter being higher than the first current threshold, control the wind turbine to shut down; in response to the DC bus voltage being higher than the second voltage threshold but not higher than the first voltage threshold for a continuous period reaching a second preset period, or the current of the converter being higher than the second current threshold but not higher than the first current threshold for a continuous period reaching a second preset period, control the wind turbine to shut down; wherein, the first preset period is longer than the second preset period.

[0067] As an exemplary embodiment, the operation control unit 103 may be configured to: control the grid-connected terminal voltage to be continuously at a target voltage value; and control the output torque of the generator to be continuously at a target torque value.

[0068] As an exemplary embodiment, the target voltage value may be set based on an upper voltage limit that the hardware of the wind turbine generator system can withstand and a voltage control requirement for a power grid power failure.

[0069] As an exemplary embodiment, the target torque value may be set based on an upper limit of the current that the hardware of the wind turbine generator system can withstand and a load reduction requirement for a power grid power failure.

[0070] As an exemplary embodiment, the converter of the wind turbine generator set includes: a machine-side converter and a grid-side converter; wherein the operation control unit 103 can be configured to: control the output voltage of the grid-side converter and the reactive current output by the machine-side converter so that the grid-connected terminal voltage is continuously at a target voltage value; or, control the output voltage of the grid-side converter and the reactive current output by the grid-side converter so that the grid-connected terminal voltage is continuously at a target voltage value; or, control the output voltage of the generator stator and the reactive current output by the machine-side converter so that the grid-connected terminal voltage is continuously at a target voltage value; or, control the output voltage of the generator stator and the reactive current output by the grid-side converter so that the grid-connected terminal voltage is continuously at a target voltage value.

[0071] As an exemplary embodiment, the converter of the wind turbine generator set includes: a machine-side converter and a grid-side converter; wherein the operation control unit 103 can be configured to: control the active current output by the machine-side converter and start the braking resistor so that the output torque of the generator is continuously at the target torque value.

[0072] As an exemplary embodiment, the operation control unit 103 can be configured to: in response to the output torque of the generator being maintained at the target torque value for a continuous period reaching a third preset period, control the generator to stop outputting the torque; wherein the first preset period is longer than or equal to the third preset period, and the third preset period is set based on the load reduction requirement for a power grid power failure.

[0073] As an exemplary embodiment, the operation control unit 103 may be configured to: control the output torque of the generator to be continuously at a target torque value through the power converter controller.

[0074] As an exemplary embodiment, the fault monitoring unit 101 may be configured to determine that a grid power failure occurs in response to power being higher than a power threshold, grid-connected current being lower than a current threshold, and grid-connected voltage being higher than a voltage threshold.

[0075] It should be understood that the specific processing performed by the control device of the wind turbine generator set according to the exemplary embodiment of the present disclosure has been referred to. Figures 2 to 5 The details have been described in detail and will not be repeated here.

[0076] It should be understood that the various units in the control device of the wind turbine generator set according to the exemplary embodiment of the present disclosure can be implemented as hardware components and / or software components. Those skilled in the art can implement the various units, for example, using a field programmable gate array (FPGA) or an application specific integrated circuit (ASIC) according to the processing performed by the defined various units.

[0077] The controller of the wind turbine generator set according to the exemplary embodiment of the present disclosure includes: a processor (not shown) and a memory (not shown), wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor is prompted to execute the control method of the wind turbine generator set as described in the above exemplary embodiment. As an example, the controller may include: a main control and / or a current converter controller of the wind turbine generator set.

[0078] According to an exemplary embodiment of the present disclosure, a computer-readable storage medium storing instructions may also be provided, wherein when the instructions are executed by at least one processor, the at least one processor is prompted to execute the control method of the wind turbine generator set as described in the above exemplary embodiment. Examples of computer-readable storage media here include: read-only memory (ROM), random access programmable read-only memory (PROM), electrically erasable programmable read-only memory (EEPROM), random access memory (RAM), dynamic random access memory (DRAM), static random access memory (SRAM), flash memory, non-volatile memory, CD-ROM, CD-R, CD+R, CD-RW, CD+RW, DVD-ROM, DVD-R, DVD+R, DVD-RW, DVD+RW, DVD-RAM, BD-ROM, BD-R, BD-R LTH, BD-RE, Blu-ray or optical disk storage, hard disk drive (HDD), solid state drive (SSD), card storage (such as, multimedia card, secure digital (SD) card or extreme digital (XD) card), magnetic tape, floppy disk, magneto-optical data storage device, optical data storage device, hard disk, solid state disk and any other device, any other device is configured to store computer programs and any associated data, data files and data structures in a non-transitory manner and provide the computer programs and any associated data, data files and data structures to a processor or computer so that the processor or computer can execute the computer program. The computer program in the above-mentioned computer-readable storage medium can be run in an environment deployed in a computer device such as a client, a host, an agent device, a server, etc. In addition, in one example, the computer program and any associated data, data files and data structures are distributed on a networked computer system, so that the computer program and any associated data, data files and data structures are stored, accessed and executed in a distributed manner by one or more processors or computers.

[0079] According to an exemplary embodiment of the present disclosure, a computer program product may be provided. Instructions in the computer program product may be executed by at least one processor to implement the control method of the wind turbine generator set as described in the above exemplary embodiment.

[0080] Those skilled in the art will readily appreciate other embodiments of the present disclosure after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses or adaptations of the present disclosure, which follow the general principles of the present disclosure and include common knowledge or customary techniques in the art that are not disclosed in the present disclosure. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present disclosure are indicated by the claims.

[0081] It should be understood that the present disclosure is not limited to the exact structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims.

Claims

1. A control method for a wind turbine generator set, characterized in that: include: Monitor whether a power failure occurs in which the grid-connected end of the wind turbine generator set is disconnected from the grid; In response to detecting a power grid power failure, switching the protection mode to a power grid power failure protection mode; In response to entering the power grid power failure protection mode, controlling the wind turbine generator set to remain in operation; In response to entering the grid power failure protection mode for a first preset time period, the wind turbine generator set is controlled to shut down.

2. The control method according to claim 1, characterized in that: Also includes: In response to entering the power grid power failure protection mode, monitoring whether the DC bus voltage is overvoltage and whether the converter current is overcurrent; In response to the DC bus voltage being higher than a first voltage threshold or the converter current being higher than a first current threshold, controlling the wind turbine generator set to shut down; In response to the DC bus voltage being higher than the second voltage threshold but not higher than the first voltage threshold for a second preset time period, or the converter current being higher than the second current threshold but not higher than the first current threshold for a second preset time period, controlling the wind turbine generator set to shut down; The first preset duration is longer than the second preset duration.

3. The control method according to claim 1, characterized in that: The steps to control the wind turbine to remain in operation include: Control the grid-connected voltage to remain at the target voltage value; The output torque of the generator is controlled to remain at the target torque value.

4. The control method according to claim 3, characterized in that: The target voltage value is set based on the upper voltage limit that the hardware of the wind turbine generator set can withstand and the voltage control requirements for power failure of the power grid; And / or, the target torque value is set based on an upper limit of current that the hardware of the wind turbine generator system can withstand and a load reduction requirement for a power grid power failure.

5. The control method according to claim 3, characterized in that: The converter of the wind turbine generator set includes: a machine-side converter and a grid-side converter; wherein the step of controlling the grid-connected terminal voltage to be continuously at a target voltage value includes: By controlling the output voltage of the grid-side converter and the reactive current output by the generator-side converter, the grid-connected voltage is kept at the target voltage value. Alternatively, the grid-connected terminal voltage is kept at a target voltage value by controlling the output voltage of the grid-side converter and the reactive current output by the grid-side converter; Alternatively, the grid-connected voltage is kept at a target voltage value by controlling the output voltage of the generator stator and the reactive current output by the machine-side converter; Alternatively, the grid-connected voltage is kept at a target voltage value by controlling the output voltage of the generator stator and the reactive current output by the grid-side converter.

6. The control method according to claim 3, characterized in that: The converter of the wind turbine generator set includes: a machine-side converter and a grid-side converter; wherein the step of controlling the output torque of the generator to continuously be at a target torque value includes: By controlling the active current output by the machine-side converter and starting the braking resistor, the output torque of the generator is kept at the target torque value.

7. The control method according to claim 3, characterized in that: The steps of controlling the wind turbine generator set to remain in operation state also include: In response to the output torque of the generator being maintained at the target torque value for a duration reaching a third preset duration, controlling the generator to stop outputting the torque; The first preset time period is longer than or equal to the third preset time period, and the third preset time period is set based on a load reduction requirement for a power grid power failure.

8. The control method according to claim 3, characterized in that: The steps of controlling the output torque of the generator to continuously be at a target torque value include: The output torque of the generator is controlled by the inverter controller to continuously maintain the target torque value.

9. The control method according to claim 1, characterized in that: The steps of monitoring whether a power failure occurs in which the grid-connected end of the wind turbine generator set is disconnected from the grid include: In response to the power being higher than a power threshold, the grid-connected terminal current being lower than a current threshold, and the grid-connected terminal voltage being higher than a voltage threshold, it is determined that a grid power failure fault occurs.

10. A control device for a wind turbine generator set, characterized in that: include: A fault monitoring unit is configured to monitor whether a grid power failure occurs in which the grid-connected end of the wind turbine generator set is disconnected from the grid; a mode switching unit, configured to switch the protection mode to a power grid power failure protection mode in response to monitoring the occurrence of a power grid power failure; An operation control unit, configured to control the wind turbine generator set to be continuously in operation in response to entering a power grid power failure protection mode; The shutdown control unit is configured to control the wind turbine generator set to shut down in response to entering the grid power failure protection mode for a first preset time period.

11. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the processor is prompted to execute the control method of a wind turbine generator set according to any one of claims 1 to 9.

12. A controller for a wind turbine generator set, characterized in that: The controller comprises: processor; A memory storing a computer program, which, when executed by a processor, prompts the processor to execute the control method for a wind turbine generator set according to any one of claims 1 to 9.

13. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the control method of the wind turbine generator set according to any one of claims 1 to 9 is implemented.

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