Island state recognition method and device for wind turbine generator system

Abstract

A method and apparatus for identifying the islanding state of a wind turbine generator set are provided. The islanding state identification method includes: determining whether the wind turbine generator set has entered a high voltage ride-through state; when it is determined that it has entered a high voltage ride-through state, determining whether the wind turbine generator set is disconnected from the power grid and is in an islanding state based on the active power value and DC bus voltage value of the wind turbine generator set.

Description

Technical Field

[0001] This disclosure generally relates to the field of power technology, and more specifically, to a method and apparatus for identifying the islanding state of a wind turbine generator set. Background Technology

[0002] For the converter of wind turbine generator set (hereinafter referred to as wind turbine or generator set), the structure of connecting the generator on the turbine side and connecting the grid on the grid side through a box-type transformer (hereinafter referred to as box transformer) is generally adopted.

[0003] As wind turbine power increases, when the grid-side transformer trips or the entire turbine's collector line is disconnected, the power transmission channel for the operating turbine is blocked, causing the turbine to momentarily enter an islanded state. The grid-side LC filter of the converter then becomes its load. At this time, the grid-side voltage is built up by the turbine itself; the higher the turbine's output power before the fault, the greater the rate and magnitude of the grid-side voltage rise. Since there is no active power transmission channel, the energy injected into the DC side by the generator will be consumed by the braking resistor. Furthermore, due to the absence of strong grid voltage, the frequency of the unit's grid side will also shift and will no longer be stable near the power frequency. For example, when a 5MW wind turbine experiences a transformer trip, the instantaneous grid-side voltage reaches 1300V, equivalent to 1.77 pu.

[0004] Existing technologies typically employ passive anti-islanding methods. To prevent false triggering, a delay is required to determine the islanding status and implement protection. However, prolonged high voltage can enter the secondary power supply system, potentially damaging the wind turbine's pitch or converter control system, causing the unit to enter an unstable state, or even burning out the unit's hardware.

[0005] Therefore, it is particularly important to quickly and accurately identify when a wind turbine has disconnected from the power grid and entered an islanded state. Summary of the Invention

[0006] An exemplary embodiment of this disclosure provides a method and apparatus for identifying the islanding state of a wind turbine generator set, which can quickly and accurately identify when a wind turbine disconnects from the power grid and enters an islanding state.

[0007] According to a first aspect of the present disclosure, a method for identifying the islanding state of a wind turbine generator set is provided, comprising: determining whether the wind turbine generator set has entered a high voltage ride-through state; when it is determined that the wind turbine generator set has entered a high voltage ride-through state, determining whether the wind turbine generator set is disconnected from the power grid and is in an islanding state based on the active power value and DC bus voltage value of the wind turbine generator set.

[0008] Optionally, when it is determined that the wind turbine has entered a high-voltage ride-through state, the step of determining whether the wind turbine is disconnected from the grid and in an islanded state based on the active power value and DC bus voltage value of the wind turbine includes: when it is determined that the wind turbine has entered a high-voltage ride-through state, determining whether the active power value of the wind turbine in the high-voltage ride-through state meets a first preset condition compared with the active power value before entering the high-voltage ride-through state; when the active power value in the high-voltage ride-through state meets the first preset condition, determining whether the DC bus voltage value of the wind turbine meets a second preset condition; when the DC bus voltage value meets the second preset condition, determining that the wind turbine is disconnected from the grid and in an islanded state.

[0009] Optionally, the first preset condition includes: the active power value of the wind turbine generator set in the high voltage ride-through state is continuously lower than a specific active power value for a period of time that reaches a first preset duration; and / or, the second preset condition includes: the DC bus voltage value exceeds the voltage threshold for triggering the opening of the braking resistor; wherein, the specific active power value is obtained based on the active power value at a specific time point before entering the high voltage ride-through state, and the interval between the specific time point and the time point of entering the high voltage ride-through state is a second preset duration.

[0010] Optionally, the specific active power value is the active power value at the specific time point at a preset ratio.

[0011] Optionally, the islanding state identification method further includes: periodically acquiring the average active power within the current time interval; storing the acquired average active power in a first-in-first-out array of a specific length before determining that the high-voltage ride-through state has been entered; and stopping updating the array after determining that the high-voltage ride-through state has been entered. The step of determining whether the active power value of the wind turbine generator in the high-voltage ride-through state meets a first preset condition compared to the active power value before entering the high-voltage ride-through state includes: when the average active power for a consecutive predetermined number of time intervals after determining that the high-voltage ride-through state has been entered is lower than the specific active power value, determining that the active power value in the high-voltage ride-through state meets the first preset condition; wherein the specific length is determined based on the length of the time interval and a second preset duration; the predetermined number is determined based on the length of the time interval and the first preset duration; and the specific active power value is determined based on the earliest average active power value in the array.

[0012] According to a second aspect of the present disclosure, an islanding state identification device for a wind turbine generator set is provided, comprising: a high voltage ride-through determination unit configured to determine whether the wind turbine generator set has entered a high voltage ride-through state; and an islanding determination unit configured to, when it is determined that the wind turbine generator set has entered a high voltage ride-through state, determine whether the wind turbine generator set is disconnected from the power grid and is in an islanding state based on the active power value and DC bus voltage value of the wind turbine generator set.

[0013] Optionally, the islanding determination unit is configured to: when it is determined that the wind turbine generator set has entered a high voltage ride-through state, determine whether the active power value of the wind turbine generator set in the high voltage ride-through state meets a first preset condition compared with the active power value before entering the high voltage ride-through state; when the active power value in the high voltage ride-through state meets the first preset condition, determine whether the DC bus voltage value of the wind turbine generator set meets a second preset condition; when the DC bus voltage value meets the second preset condition, determine that the wind turbine generator set is disconnected from the grid and is in an islanding state.

[0014] Optionally, the first preset condition includes: the active power value of the wind turbine generator set in the high voltage ride-through state is continuously lower than a specific active power value for a period of time that reaches a first preset duration; and / or, the second preset condition includes: the DC bus voltage value exceeds the voltage threshold for triggering the opening of the braking resistor; wherein, the specific active power value is obtained based on the active power value at a specific time point before entering the high voltage ride-through state, and the interval between the specific time point and the time point of entering the high voltage ride-through state is a second preset duration.

[0015] Optionally, the specific active power value is the active power value at the specific time point at a preset ratio.

[0016] Optionally, the islanding state identification device further includes: an active power determination unit, configured to periodically acquire the average active power within the current time interval; before determining that the high voltage ride-through state has been entered, store the acquired average active power in a first-in-first-out array of a specific length; after determining that the high voltage ride-through state has been entered, stop updating the array; wherein, the islanding determination unit is configured to: when, after determining that the high voltage ride-through state has been entered, the average active power for a consecutive predetermined number of time intervals is lower than the specific active power value, determine that the active power value in the high voltage ride-through state meets a first preset condition; wherein, the specific length is determined based on the length of the time interval and a second preset duration; the predetermined number is determined based on the length of the time interval and the first preset duration; the specific active power value is determined based on the earliest average active power in the array.

[0017] Optionally, the islanding status identification device is installed in the converter controller or main controller of the wind turbine generator set.

[0018] According to a third aspect of the present disclosure, a computer-readable storage medium storing a computer program is provided, which, when executed by a processor, causes the processor to perform the islanding state identification method for a wind turbine generator as described above.

[0019] According to a fourth aspect of the present disclosure, a controller 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 islanding state identification method for a wind turbine generator as described above.

[0020] Optionally, the controller is located in the converter controller or main controller of the wind turbine generator set.

[0021] According to a fifth aspect of the present disclosure, a wind turbine generator set is provided, including the islanding status identification device as described above, or the controller as described above.

[0022] The islanding state identification method and apparatus for wind turbine generator sets according to the exemplary embodiments of this disclosure can comprehensively utilize grid-side voltage, DC-side voltage and active power to quickly and accurately determine the islanding condition of the wind turbine disconnected from the grid, thereby enabling the unit to shut down quickly and protecting the unit's hardware from damage.

[0023] Further aspects and / or advantages of the general concept of this disclosure will be set forth in part in the description which follows, and in part will be clear from the description or may be learned by practice of the general concept of this disclosure. Attached Figure Description

[0024] The above and other objects and features of exemplary embodiments of this disclosure will become clearer from the following description taken in conjunction with the accompanying drawings, which exemplarily illustrate the embodiments, wherein:

[0025] Figure 1 A flowchart illustrating an islanding state identification method for a wind turbine generator set according to an exemplary embodiment of the present disclosure is shown.

[0026] Figure 2 A flowchart illustrating a method for determining whether a wind turbine generator is disconnected from the grid and in an islanded state according to an exemplary embodiment of the present disclosure;

[0027] Figure 3 A flowchart illustrating a method for identifying the islanding state of a wind turbine generator according to another exemplary embodiment of the present disclosure;

[0028] Figure 4 This illustrates an example of the effectiveness of existing technologies in identifying isolated states.

[0029] Figure 5An example of the island state identification effect according to an exemplary embodiment of the present disclosure is shown;

[0030] Figure 6 A structural block diagram of an islanding status identification device for a wind turbine generator set according to an exemplary embodiment of the present disclosure is shown. Detailed Implementation

[0031] The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings, examples of which are illustrated in the drawings, wherein the same reference numerals always refer to the same parts. The embodiments will now be described with reference to the accompanying drawings in order to explain this disclosure.

[0032] Figure 1 A flowchart illustrating an islanding state identification method for a wind turbine generator set according to an exemplary embodiment of the present disclosure is shown.

[0033] As an example, the generator-side converter of a wind turbine can be connected to the generator, and the grid-side converter can be connected to the grid via a box-type transformer.

[0034] As an example, the causes of wind turbine generators entering islanded mode may include at least: transformer tripping and complete disconnection of the turbine's current collector. It should be understood that other types of causes may also lead to wind turbine generators entering islanded mode, which will not be elaborated upon here.

[0035] Reference Figure 1 In step S10, it is determined whether the wind turbine generator set has entered the high voltage ride-through (HVRT) state.

[0036] It should be understood that whether a wind turbine has entered a high-voltage ride-through state can be determined through appropriate methods. As an example, a wind turbine can be considered to have entered a high-voltage ride-through state when the grid-side positive-sequence voltage value exceeds a preset voltage value for a specific duration. The specific values ​​of the preset voltage value and the specific duration can be set according to actual conditions and specific needs. For example, the preset voltage value can be set to 1.13 pu, and the specific duration can be set to 5 ms.

[0037] When it is determined in step S10 that the high voltage ride-through state has been entered, step S20 is executed to determine whether the wind turbine generator set is disconnected from the grid and in an islanded state based on the active power value and DC bus voltage value of the wind turbine generator set.

[0038] As an example, when the active power value of the wind turbine generator set in the high voltage ride-through state meets the first preset condition and the DC bus voltage value meets the second preset condition, it can be determined that the wind turbine generator set is disconnected from the grid and is in an islanded state.

[0039] The following will combine Figure 2 An exemplary embodiment of step S20 will be described below.

[0040] Figure 2 A flowchart illustrating a method for determining whether a wind turbine generator is disconnected from the power grid and in an islanded state, according to an exemplary embodiment of the present disclosure.

[0041] Reference Figure 2 When it is determined in step S10 that the high voltage ride-through state has been entered, step S201 is executed to determine whether the active power value of the wind turbine generator set in the high voltage ride-through state meets the first preset condition compared with the active power value before entering the high voltage ride-through state.

[0042] As an example, the first preset condition may include: the active power value of the wind turbine generator set under high voltage ride-through condition is continuously lower than a specific active power value for a period of time that reaches a first preset duration.

[0043] As an example, the specific active power value can be obtained based on the active power value at a specific time point before entering the high voltage ride-through state, with a second preset time interval between the specific time point and the time point of entering the high voltage ride-through state.

[0044] As an example, the specific active power value may be a preset proportion of the active power value at the specific time point. It should be understood that the value of the preset proportion can be determined according to the actual situation and specific needs; for example, the value of the preset proportion may be set to 30%.

[0045] As an example, the islanding state identification method for a wind turbine generator set according to an exemplary embodiment of the present disclosure may further include: periodically acquiring the average active power within the current time interval; storing the average active power acquired each time into a first-in-first-out array of a specific length before determining that a high-voltage ride-through state has been entered; and stopping updating the array after determining that a high-voltage ride-through state has been entered.

[0046] Accordingly, as an example, step S201 may include: when the average active power over a predetermined number of consecutive time intervals is lower than the specific active power value after determining that the high-voltage ride-through state has been entered, determining that the active power value in the high-voltage ride-through state meets a first preset condition. Wherein, the specific length is determined based on the length of the time interval and a second preset duration; the predetermined number is determined based on the length of the time interval and the first preset duration; and the specific active power value is determined based on the earliest average active power value in the array.

[0047] When it is determined in step S201 that the active power value under the high voltage ride-through state meets the first preset condition, step S202 is executed to determine whether the DC bus voltage value of the wind turbine generator meets the second preset condition.

[0048] As an example, if step S201 determines that the active power value under the high voltage ride-through state does not meet the first preset condition, step S201 can continue to be executed.

[0049] As an example, the second preset condition may include: the DC bus voltage value exceeds the voltage threshold that triggers the activation of the braking resistor. The voltage threshold that triggers the activation of the braking resistor can be understood as: when the DC bus voltage value exceeds this voltage threshold, the braking resistor will be activated.

[0050] When it is determined in step S202 that the DC bus voltage value meets the second preset condition, step S203 is executed to determine that the wind turbine generator set is disconnected from the power grid and is in an islanded state.

[0051] As an example, when it is determined in step S202 that the DC bus voltage value does not meet the second preset condition, the process can return to step S201.

[0052] Furthermore, as an example, the islanding state identification method for a wind turbine generator set according to an exemplary embodiment of this disclosure may further include: controlling the wind turbine generator set to shut down when it is determined that the wind turbine generator set is disconnected from the grid and in an islanding state. For example, the shutdown of the wind turbine generator set can be achieved by blocking the control pulses on the grid side of the converter.

[0053] According to exemplary embodiments of this disclosure, by utilizing the changes in grid-side voltage, active power, and bus voltage collected by the converter, it is possible to quickly and accurately determine (e.g., when the transformer trips) whether the generating unit is disconnected from the grid and enters an islanded state. The determination time can be reduced from more than hundreds of milliseconds to less than tens of milliseconds, thereby enabling the unit to shut down quickly and avoiding the problem of grid-side voltage rising rapidly and remaining too high for a long time, which could burn out important components of the unit.

[0054] Figure 3 A flowchart illustrating an islanding state identification method for a wind turbine generator set according to another exemplary embodiment of the present disclosure is shown.

[0055] Reference Figure 3 In step S301, the average active power is calculated every 5ms to obtain the average active power over these 5ms.

[0056] In step S302, the average active power value calculated in step S301 for the current 5ms is stored in an array of length 20. The length is 20, meaning it can hold a maximum of 20 average active power values.

[0057] This array is a first-in-first-out array, meaning that each time the average active power is stored, the previously stored average active power is shifted one position to the right.

[0058] In step S303, it is determined whether to enter the high-penetration state.

[0059] When it is determined in step S303 that the system has entered the high-voltage transmission state, step S304 is executed, and the average active power is calculated every 5ms without updating the array. In other words, after the high-voltage transmission state is determined, the data in the array remains unchanged.

[0060] In step S305, the average active power after entering the high-voltage state is compared with the average active power 100ms before entering the high-voltage state (i.e., the earliest average active power in the array). When it is determined in step S305 that the average active power of three consecutive active power values ​​after entering the high-voltage state is less than 30% of the average active power 100ms before entering the high-voltage state, step S306 is executed to continue to determine the status of the bus voltage at this time.

[0061] When it is determined in step S306 that the bus voltage is greater than the opening voltage of the braking resistor, step S307 is executed to determine that the unit has entered the islanding state and immediately trigger the unit's shutdown command.

[0062] It should be further clarified that when a generating unit enters high-voltage transmission mode, it does not necessarily enter islanded mode. Grid connection regulations require that after a unit enters high-voltage transmission mode due to a rise in grid voltage, the unit's output active power must not fall below 50% of the pre-fault active power for a short period. However, when a unit enters islanded mode due to reasons such as transformer tripping, the voltage rises, and the unit's active power has no transmission channel, thus the active power will drop to near zero. Based on this characteristic, the judgment condition is set so that the unit's active power is below 30% of the active power 100ms before high-voltage transmission mode before proceeding to the next step of bus voltage judgment.

[0063] In addition, considering that it is possible that when the unit enters high-voltage operation, the energy input of the generator will decrease rapidly (for example, due to the mechanical inertia of the impeller, rapid changes in energy at the millisecond level are rare), the judgment of bus voltage is added: that is, if the active power output on the grid side decreases rapidly and the bus voltage continues to rise (energy cannot be transmitted to the grid and can only be consumed by the braking resistor), it can be immediately determined that the unit has entered the islanding state, and the unit shutdown fault can be triggered immediately, blocking the control pulses on the grid side of the converter.

[0064] Figure 4 An example illustrating the effectiveness of existing technologies in isolating state identification is shown. Figure 5 Examples illustrating the islanding state identification effect according to exemplary embodiments of the present disclosure are shown. All simulations use simulation software to demonstrate the time from the occurrence of a transformer trip to the blocking of the converter's grid-side control pulse, based on existing technology and the present disclosure. The simulation is set to enter islanding state at 2.1 seconds. Figure 4 and Figure 5In the graph above, the horizontal axis indicates time, the vertical axis indicates the three-phase voltage value on the grid side, and in the graph below, when the vertical axis is 0, it indicates the control pulse on the grid side of the converter that is blocked; when the vertical axis is 1, it indicates the control pulse on the grid side of the converter that is transmitting normally.

[0065] It can be seen that the protection delay of the prior art is about 65ms, and the maximum grid-side voltage reaches around 2300V; the protection delay of this disclosure is 22ms, and the maximum grid-side voltage is about 1800V. According to the exemplary embodiment of this disclosure, by comprehensively utilizing the grid-side voltage, DC-side voltage, and the rapid drop in active power, the islanding condition of the unit can be quickly determined, enabling rapid shutdown of the unit and further protecting the unit's hardware from damage.

[0066] Figure 6 A structural block diagram of an islanding status identification device for a wind turbine generator set according to an exemplary embodiment of the present disclosure is shown.

[0067] like Figure 6 As shown, the islanding status identification device for a wind turbine generator set according to an exemplary embodiment of the present disclosure includes: a high voltage ride-through determination unit 10 and an islanding determination unit 20.

[0068] Specifically, the high voltage ride-through determination unit 10 is configured to determine whether the wind turbine generator has entered a high voltage ride-through state.

[0069] The islanding determination unit 20 is configured to determine whether the wind turbine generator is disconnected from the grid and in an islanded state when it is determined to enter a high voltage ride-through state, based on the active power value and DC bus voltage value of the wind turbine generator.

[0070] As an example, the islanding determination unit 20 can be configured to: when it is determined that the wind turbine generator set has entered a high voltage ride-through state, determine whether the active power value of the wind turbine generator set in the high voltage ride-through state meets a first preset condition compared with the active power value before entering the high voltage ride-through state; when the active power value in the high voltage ride-through state meets the first preset condition, determine whether the DC bus voltage value of the wind turbine generator set meets a second preset condition; when the DC bus voltage value meets the second preset condition, determine that the wind turbine generator set is disconnected from the grid and is in an islanding state.

[0071] As an example, the first preset condition may include: the active power value of the wind turbine generator set in the high voltage ride-through state is continuously lower than a specific active power value for a period of time that reaches a first preset duration, wherein the specific active power value is obtained based on the active power value at a specific time point before entering the high voltage ride-through state, and the interval between the specific time point and the time point of entering the high voltage ride-through state is a second preset duration.

[0072] As an example, the specific active power value may be the active power value at a specific time point at a preset ratio.

[0073] As an example, the second preset condition may include: the DC bus voltage value exceeds the voltage threshold that triggers the opening of the braking resistor.

[0074] As an example, the islanding state identification device may further include: an active power determination unit (not shown), configured to periodically acquire the average active power within the current time interval; before determining that the high voltage ride-through state has been entered, store the average active power acquired each time into a first-in-first-out array of a specific length; and after determining that the high voltage ride-through state has been entered, stop updating the array.

[0075] Accordingly, the islanding determination unit 20 can be configured to: determine that the active power value in the high voltage ride-through state satisfies a first preset condition when the average active power value for a consecutive predetermined number of time intervals is lower than the specific active power value after determining that the high voltage ride-through state has been entered; wherein, the specific length is determined based on the length of the time interval and a second preset duration; the predetermined number is determined based on the length of the time interval and the first preset duration; and the specific active power value is determined based on the earliest average active power value in the array.

[0076] As an example, the islanding status identification device according to an exemplary embodiment of the present disclosure may be installed in the converter controller or main controller of a wind turbine generator set.

[0077] It should be understood that the specific processing performed by the islanding status identification device for a wind turbine generator according to the exemplary embodiments of this disclosure has been referenced. Figures 1 to 5 A detailed description has been provided, and the relevant details will not be repeated here.

[0078] It should be understood that the various units in the islanding status identification device for a wind turbine generator according to exemplary embodiments of this disclosure may be implemented as hardware components and / or software components. Those skilled in the art can implement the various units, for example, using field-programmable gate arrays (FPGAs) or application-specific integrated circuits (ASICs), based on the processes performed by each defined unit.

[0079] An exemplary embodiment of this disclosure provides a computer-readable storage medium storing a computer program that, when executed by a processor, causes the processor to perform the islanding state identification method for a wind turbine generator as described in the exemplary embodiment above. The computer-readable storage medium is any data storage device capable of storing data read from a computer system. Examples of computer-readable storage media include: read-only memory, random access memory, read-only optical disk, magnetic tape, floppy disk, optical data storage device, and carrier waves (such as data transmission via the Internet through wired or wireless transmission paths).

[0080] The controller according to an exemplary embodiment of the present disclosure includes a processor (not shown) and a memory (not shown), wherein the memory stores a computer program that, when executed by the processor, causes the processor to perform the islanding state identification method for a wind turbine generator as described in the exemplary embodiment above.

[0081] As an example, the controller according to an exemplary embodiment of the present disclosure may be located in the converter controller or the main controller of a wind turbine generator set.

[0082] A wind turbine generator set according to an exemplary embodiment of the present disclosure includes: an islanding status identification device as described in the exemplary embodiment above, or a controller as described in the exemplary embodiment above.

[0083] While some exemplary embodiments of this disclosure have been shown and described, those skilled in the art will understand that modifications may be made to these embodiments without departing from the principles and spirit of this disclosure, which are defined by the claims and their equivalents.

Claims

1. A method for identifying the islanding state of a wind turbine generator set, characterized in that, include: Determine whether the wind turbine generator has entered a high-voltage ride-through state; When it is determined that the wind turbine has entered a high voltage ride-through state, the active power value and DC bus voltage value of the wind turbine are used to determine whether the wind turbine is disconnected from the grid and in an islanded state.

2. The island state identification method according to claim 1, characterized in that, When it is determined that the wind turbine has entered a high-voltage ride-through state, the steps to determine whether the wind turbine is isolated from the grid based on the active power value and DC bus voltage value of the wind turbine include: When it is determined that the wind turbine generator set has entered the high voltage ride-through state, it is determined whether the active power value of the wind turbine generator set in the high voltage ride-through state meets the first preset condition compared with the active power value before entering the high voltage ride-through state. When the active power value under high voltage ride-through condition meets the first preset condition, determine whether the DC bus voltage value of the wind turbine generator meets the second preset condition. When the DC bus voltage value meets the second preset condition, it is determined that the wind turbine generator is disconnected from the grid and is in an islanded state.

3. The island state identification method according to claim 2, characterized in that, The first preset condition includes: the active power value of the wind turbine generator set under high voltage ride-through condition is continuously lower than a specific active power value for a period of time that reaches the first preset duration; And / or, the second preset condition includes: the DC bus voltage value exceeds the voltage threshold that triggers the opening of the braking resistor; The specific active power value is obtained based on the active power value at a specific time point before entering the high voltage ride-through state, and the time point between the specific time point and the time point of entering the high voltage ride-through state is spaced out by a second preset time period.

4. The islanding state recognition method according to claim 3, characterized by, The specific active power value is the active power value at the specific time point at a preset ratio.

5. The islanding state recognition method according to claim 3, characterized by, The island state identification method also includes: Periodically obtain the average active power within the current time interval; Before entering the high-voltage ride-through state, the average active power obtained each time is stored in a first-in-first-out array of a specific length; Once the high-voltage ride-through state is determined, the array updates are stopped; The step of determining whether the active power value of the wind turbine generator set under high voltage ride-through condition meets the first preset condition compared with the active power value before entering the high voltage ride-through condition includes: When the average active power value for a predetermined number of consecutive time intervals is lower than the specific active power value after the high voltage ride-through state is determined, the active power value in the high voltage ride-through state is determined to meet the first preset condition. The specific length is determined based on the length of the time interval and the second preset duration; the predetermined quantity is determined based on the length of the time interval and the first preset duration; and the specific active power value is determined based on the earliest average active power value in the array.

6. An islanding detection device for a wind power plant, characterized in that include: The high-voltage ride-through determination unit is configured to determine whether the wind turbine generator has entered a high-voltage ride-through state. The islanding determination unit is configured to determine whether the wind turbine generator is disconnected from the grid and in an islanded state when it is determined to enter a high voltage ride-through state, based on the active power value and DC bus voltage value of the wind turbine generator.

7. The islanding state recognition apparatus according to claim 6, characterized by The islanding status identification device is installed in the converter controller or main controller of the wind turbine generator set.

8. A computer readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it causes the processor to perform the islanding state identification method for wind turbine generators as described in any one of claims 1 to 5.

9. A controller characterized by comprising: The controller includes: processor; A memory storing a computer program that, when executed by a processor, causes the processor to perform the islanding state identification method for a wind turbine generator as described in any one of claims 1 to 5.

10. The controller of claim 9, wherein, The controller is located in the converter controller or main controller of the wind turbine generator set.

11. A wind power unit, characterized in that Includes the islanding status identification device as described in any one of claims 6 to 7, or the controller as described in any one of claims 9 to 10.

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