Low voltage ride through detection method and apparatus

Abstract

A low voltage ride through detection method and device are provided. The low voltage ride through detection method comprises: determining an adjustment value of a preset parameter of a power grid based on a grid voltage, wherein the preset parameter comprises at least one of current, current frequency and power factor angle; adjusting the preset parameter of the power grid based on the adjustment value; and detecting whether the power grid satisfies a low voltage ride through condition based on the grid voltage after the preset parameter of the power grid is adjusted, thereby enabling a wind power generator to accurately identify a power grid fault under a weak power grid to enter low ride through, while avoiding instability of a power grid fault ride through system under a weak power grid.

Description

Technical Field

[0001] This disclosure relates to the field of wind power generation technology. More specifically, this disclosure relates to a low voltage ride-through detection method and apparatus. Background Technology

[0002] When wind turbines are connected to a weak power grid, the voltage drop caused by the interaction of the turbine's grid current and line impedance has a significant impact on the turbine's terminal voltage. When a fault occurs at a remote end of the power grid, the turbine's terminal voltage may not drop, causing system oscillations. Summary of the Invention

[0003] An exemplary embodiment of this disclosure provides a low-voltage ride-through detection method and apparatus to address the instability problem of power grid fault ride-through systems under weak power grid conditions.

[0004] According to an exemplary embodiment of the present disclosure, a low-voltage ride-through detection method is provided, comprising: determining an adjustment value for preset parameters of the power grid based on the grid voltage, wherein the preset parameters include at least one of current, current frequency, and power factor angle; adjusting the preset parameters of the power grid based on the adjustment value; and detecting whether the power grid meets the low-voltage ride-through conditions based on the grid voltage after the preset parameters of the power grid have been adjusted.

[0005] Optionally, the step of determining the adjustment value of the preset parameters of the power grid based on the grid voltage may include: obtaining the Q-axis component of the grid voltage; and calculating the active current limit value of the wind turbine output based on the Q-axis component of the grid voltage.

[0006] Optionally, the step of obtaining the Q-axis component of the grid voltage may include: calculating the Q-axis component of the grid voltage using a converter phase-locked loop.

[0007] Optionally, the step of calculating the active current limit value of the wind turbine output based on the Q-axis component of the grid voltage may include: filtering the Q-axis component of the grid voltage; and calculating the active current limit value of the wind turbine output based on the processed Q-axis component.

[0008] Optionally, the step of determining the adjustment value of the preset parameters of the power grid based on the grid voltage may include: calculating the Q-axis component of the grid voltage through the converter phase-locked loop; filtering the Q-axis component of the grid voltage; and calculating the active current limit value of the wind turbine output based on the processed Q-axis component.

[0009] Optionally, the step of determining the adjustment value of the preset parameters of the power grid based on the grid voltage may further include: performing low-pass filtering on the active current limit value through a variable rate filtering method.

[0010] Optionally, the step of calculating the active current limit value of the wind turbine output based on the processed Q-axis component may include: calculating the apparent current output of the wind turbine based on the processed Q-axis component and the rated grid-connected apparent current of the wind turbine; and calculating the active current limit value of the wind turbine output based on the apparent current output of the wind turbine.

[0011] Optionally, the step of detecting whether the power grid meets the low-voltage ride-through condition based on the power grid voltage after the preset parameters of the power grid are adjusted may include: obtaining the D-axis component and Q-axis component of the power grid voltage after the preset parameters of the power grid are adjusted; calculating the vector sum of the D-axis component and Q-axis component of the power grid voltage to obtain the positive-sequence voltage amplitude of the power grid voltage; performing low-pass filtering on the positive-sequence voltage amplitude; and detecting whether the power grid meets the low-voltage ride-through condition based on the processed positive-sequence voltage amplitude and the preset low-voltage ride-through threshold.

[0012] Optionally, the step of detecting whether the power grid meets the low-voltage ride-through condition based on the processed positive-sequence voltage amplitude and the preset low-voltage ride-through threshold may include: calculating the difference between the preset low-voltage ride-through threshold and the processed positive-sequence voltage amplitude; inputting the difference to the hysteresis controller; when the difference is greater than the hysteresis controller's entry hysteresis value, a delay counter starts counting, and when the count value of the delay counter reaches the target delay, it is determined that the power grid meets the low-voltage ride-through condition; when the difference is less than the hysteresis controller's exit hysteresis value, a delay counter starts counting, and when the count value of the delay counter reaches the target delay, it is determined that the power grid does not meet the low-voltage ride-through condition.

[0013] According to an exemplary embodiment of the present disclosure, a low-voltage ride-through detection device is provided, comprising: an adjustment value determination unit configured to determine an adjustment value for preset parameters of the power grid based on the grid voltage, wherein the preset parameters include at least one of current, current frequency, and power factor angle; a parameter adjustment unit configured to adjust the preset parameters of the power grid based on the adjustment value; and a low-voltage ride-through detection unit configured to detect whether the power grid meets the low-voltage ride-through conditions based on the grid voltage after the preset parameters of the power grid have been adjusted.

[0014] Optionally, the adjustment value determination unit can be configured to: acquire the Q-axis component of the grid voltage; and calculate the active current limit value output by the wind turbine generator based on the Q-axis component of the grid voltage.

[0015] Optionally, the adjustment value determination unit can be configured to calculate the Q-axis component of the grid voltage via the converter phase-locked loop.

[0016] Optionally, the adjustment value determination unit can be configured to: filter the Q-axis component of the grid voltage; and calculate the active current limit value of the wind turbine output based on the processed Q-axis component.

[0017] Optionally, the adjustment value determination unit can be configured to: calculate the Q-axis component of the grid voltage through the converter phase-locked loop; filter the Q-axis component of the grid voltage; and calculate the active current limit value of the wind turbine output based on the processed Q-axis component.

[0018] Optionally, the adjustment value determination unit can be configured to perform low-pass filtering on the active current limit value using a variable-rate filtering method.

[0019] Optionally, the adjustment value determination unit can be configured to: calculate the apparent current output by the wind turbine generator based on the processed Q-axis component and the rated grid-connected apparent current of the wind turbine generator set; and calculate the active current limit value output by the wind turbine generator based on the apparent current output by the wind turbine generator set.

[0020] Optionally, the low-voltage ride-through detection unit can be configured to: acquire the D-axis and Q-axis components of the grid voltage after the preset parameters of the grid are adjusted; calculate the vector sum of the D-axis and Q-axis components of the grid voltage to obtain the positive-sequence voltage amplitude of the grid voltage; perform low-pass filtering on the positive-sequence voltage amplitude; and detect whether the grid meets the low-voltage ride-through conditions based on the processed positive-sequence voltage amplitude and the preset low-voltage ride-through threshold.

[0021] Optionally, the low-voltage ride-through detection unit can be configured to: calculate the difference between a preset low-voltage ride-through threshold and the processed positive-sequence voltage amplitude; input the difference to a hysteresis controller; when the difference is greater than the hysteresis controller's entry hysteresis value, a delay counter starts counting, and when the delay counter's count reaches the target delay, it is determined that the power grid meets the low-voltage ride-through condition; when the difference is less than the hysteresis controller's exit hysteresis value, a delay counter starts counting, and when the delay counter's count reaches the target delay, it is determined that the power grid does not meet the low-voltage ride-through condition.

[0022] Optionally, the device may be installed in the converter controller of the wind turbine generator set.

[0023] According to exemplary embodiments of the present disclosure, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements a low-voltage ride-through detection method according to exemplary embodiments of the present disclosure.

[0024] According to an exemplary embodiment of the present disclosure, a computing device is provided, comprising: at least one processor; and at least one memory storing a computer program that, when executed by the at least one processor, implements a low-voltage ride-through detection method according to an exemplary embodiment of the present disclosure.

[0025] According to an exemplary embodiment of the present disclosure, a computer program product is provided, wherein the instructions in the computer program product are executable by a processor of a computer device to perform a low voltage ride-through detection method according to an exemplary embodiment of the present disclosure.

[0026] The low-voltage ride-through detection method and apparatus according to exemplary embodiments of the present disclosure first determine an adjustment value for preset parameters of the power grid based on the grid voltage, wherein the preset parameters include at least one of current, current frequency, and power factor angle; adjust the preset parameters of the power grid based on the adjustment value; and then detect whether the power grid meets the low-voltage ride-through conditions based on the grid voltage after the preset parameters of the power grid have been adjusted. This enables wind turbines to accurately identify grid faults under weak grid conditions and enter low-voltage ride-through mode, thereby avoiding instability of the grid fault ride-through system under weak grid conditions.

[0027] 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

[0028] 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:

[0029] Figure 1 A flowchart illustrating a low-voltage ride-through detection method according to an exemplary embodiment of the present disclosure is shown;

[0030] Figure 2 A schematic diagram illustrating the principle of low-pass hysteresis is shown;

[0031] Figure 3 A block diagram illustrating a low-voltage ride-through detection device according to an exemplary embodiment of the present disclosure; and

[0032] Figure 4 A schematic diagram of a computing device according to an exemplary embodiment of the present disclosure is shown. Detailed Implementation

[0033] Exemplary embodiments of the present 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 components. The embodiments will now be described with reference to the accompanying drawings in order to explain the present disclosure.

[0034] Fan terminal voltage It can be determined by the node voltage of the power grid. Line impedance voltage drop To constrain. For example, Line impedance voltage drop Related to line impedance Z and fan output current amplitude Related to current frequency f, power factor angle, etc. For example, Therefore, even if the grid node voltage has dropped, the line impedance voltage drop can ensure that the turbine terminal voltage is not lower than the undervoltage threshold, thus preventing the wind turbine from responding to undervoltage.

[0035] This disclosure proposes a scheme to reduce impedance voltage drop by injecting disturbances into the power grid, thereby enabling the detection of low voltage ride-through of wind turbines.

[0036] Figure 1 A flowchart illustrating a low-voltage ride-through detection method according to an exemplary embodiment of the present disclosure is shown.

[0037] Reference Figure 1 In step S101, the adjustment value of the preset parameters of the power grid is determined based on the power grid voltage.

[0038] In exemplary embodiments of this disclosure, the preset parameter may include at least one of current, current frequency, and power factor angle. That is, if the preset parameter is at least one of current, current frequency, and power factor angle, an adjustment value for said at least one can be determined based on the grid voltage. For example, if the preset parameter is current, an adjustment value for the grid current can be determined based on the grid voltage; if the preset parameter is current frequency, an adjustment value for the grid current frequency can be determined based on the grid voltage; if the preset parameter is power factor angle, an adjustment value for the grid power factor angle can be determined based on the grid voltage; if the preset parameter is current and power factor angle, an adjustment value for both the grid current and power factor angle can be determined based on the grid voltage; if the preset parameter is current and current frequency, an adjustment value for both the grid current and current frequency can be determined based on the grid voltage; if the preset parameter is current, current frequency, and power factor angle, an adjustment value for the grid current, current frequency, and power factor angle can be determined based on the grid voltage.

[0039] In an exemplary embodiment of this disclosure, when determining the adjustment value of the preset parameters of the power grid based on the grid voltage, the Q-axis component of the grid voltage can be obtained first, and then the active current limit value output by the wind turbine can be calculated based on the Q-axis component of the grid voltage.

[0040] In an exemplary embodiment of this disclosure, when obtaining the Q-axis component of the grid voltage, the Q-axis component of the grid voltage can be calculated using the converter phase-locked loop (PLL) of the grid. Specifically, the Q-axis component of the grid voltage calculated by the PLL can be used as a triggering factor for the disturbance current.

[0041] In an exemplary embodiment of this disclosure, when calculating the active current limit value of the wind turbine output based on the Q-axis component of the grid voltage, the Q-axis component of the grid voltage can be filtered first, and then the active current limit value of the wind turbine output can be calculated based on the processed Q-axis component, thereby improving the stability of the grid. Preferably, in order to quickly perform low-voltage ride-through detection, the filter delay when filtering the Q-axis component of the grid voltage should preferably not exceed 1 / 4 of the power frequency cycle.

[0042] In an exemplary embodiment of this disclosure, when determining the adjustment value of the preset parameters of the power grid based on the grid voltage, the Q-axis component of the grid voltage can be calculated first through the converter phase-locked loop, the Q-axis component of the grid voltage can be filtered, and then the active current limit value output by the wind turbine generator can be calculated based on the processed Q-axis component.

[0043] In an exemplary embodiment of this disclosure, when calculating the active current limit value of the wind turbine output based on the processed Q-axis component, the apparent current output by the wind turbine can first be calculated based on the processed Q-axis component and the rated grid-connected apparent current of the wind turbine generator set, and then the active current limit value of the wind turbine output can be calculated based on the apparent current output by the wind turbine. For example, it can be calculated according to the formula... To calculate the active current limit value output by the wind turbine. Here, I s E represents the apparent current on the inverter side of the converter. q I is the Q-axis component of the grid voltage calculated by the converter phase-locked loop. s_rated I is the rated grid-connected apparent current of the unit. q_ref I is the reference value for the reactive current of the generator unit. d_max K is the active current limiting factor, and K is the intensity adjustment gain.

[0044] In an exemplary embodiment of this disclosure, the calculated active current can also be limited I. d_max Filtering is performed. The calculated active current is limited by I. d_max Filtering can be performed using a variable-rate filtering method. For example, the calculated active current I can be limited. d_max Variable rate filtering is used. When I d_max No filtering when I decreases d_max When the value increases, a low-pass filter is applied.

[0045] In step S102, the preset parameters of the power grid are adjusted based on the determined adjustment values.

[0046] Specifically, if the preset parameter is at least one of current, current frequency, and power factor angle, then the at least one parameter can be adjusted based on a determined adjustment value. For example, if the preset parameter is current, the grid current can be adjusted based on a determined adjustment value; if the preset parameter is current frequency, the grid current frequency can be adjusted based on a determined adjustment value; if the preset parameter is power factor angle, the grid power factor angle can be adjusted based on a determined adjustment value; if the preset parameter is current and power factor angle, the grid current and power factor angle can be adjusted based on determined adjustment values ​​for current and power factor angle, respectively; if the preset parameter is current and current frequency, the grid current and current frequency can be adjusted based on determined adjustment values ​​for current and current frequency, respectively; if the preset parameter is current, current frequency, and power factor angle, the grid current, current frequency, and current factor angle can be adjusted based on determined adjustment values ​​for current, current frequency, and power factor angle, respectively.

[0047] In step S103, based on the grid voltage after the preset parameters of the grid have been adjusted, it is detected whether the grid meets the low voltage ride-through condition.

[0048] In an exemplary embodiment of this disclosure, when detecting whether the power grid meets the low-voltage ride-through condition based on the power grid voltage after the preset parameters of the power grid have been adjusted, the D-axis and Q-axis components of the power grid voltage after the preset parameters of the power grid have been adjusted can be obtained first. The vector sum of the D-axis and Q-axis components of the power grid voltage after the preset parameters have been adjusted is calculated to obtain the positive-sequence voltage amplitude of the power grid voltage after the preset parameters have been adjusted. The positive-sequence voltage amplitude is then low-pass filtered. Finally, the power grid is detected as meeting the low-voltage ride-through condition based on the processed positive-sequence voltage amplitude and the preset low-voltage ride-through threshold. For example, the positive-sequence components of the three-phase voltage can be extracted first using the symmetrical component method, and then the Clark and Park transforms of the three-phase voltage positive-sequence components can be performed to obtain the D-axis and Q-axis components of the power grid voltage.

[0049] In an exemplary embodiment of this disclosure, when detecting whether the power grid meets the low-voltage ride-through condition based on the processed positive-sequence voltage amplitude and a preset low-voltage ride-through threshold, the difference between the preset low-voltage ride-through threshold and the processed positive-sequence voltage amplitude can be calculated first. This difference is then input to the hysteresis controller. When the difference between the preset low-voltage ride-through threshold and the processed positive-sequence voltage amplitude is greater than the hysteresis controller's entry hysteresis value, a delay counter starts counting. When the count value of the delay counter reaches the target delay, it is determined that the power grid meets the low-voltage ride-through condition. When the difference between the preset low-voltage ride-through threshold and the processed positive-sequence voltage amplitude is less than the hysteresis controller's exit hysteresis value, a delay counter starts counting. When the count value of the delay counter reaches the target delay, it is determined that the power grid does not meet the low-voltage ride-through condition.

[0050] Figure 2 This diagram illustrates the principle of low-voltage hysteresis. Hysteresis is used to avoid boundary oscillations. Without hysteresis, assuming the low-voltage threshold is 0.9 pu, when the voltage drops below 0.9 pu, the converter enters low-voltage hysteresis, begins reactive power compensation, and the voltage rises. When the voltage rises above 0.9 pu, the converter exits low-voltage hysteresis. Reactive power is recovered, the voltage drops below 0.9 pu, and the converter re-enters low-voltage hysteresis. This repeated process causes boundary oscillations.

[0051] Employing a hysteresis controller, such as Figure 2 As shown, the low-voltage enable threshold for entering low-voltage mode is set to, for example, 0.87 pu, and the low-voltage exit threshold is set to, for example, 0.9 pu. Thus, when the voltage is below 0.87 pu, the converter enters low-voltage mode and begins reactive power compensation. As long as the voltage does not rise above 0.9 pu, the converter will not exit low-voltage mode, thereby avoiding boundary oscillations. The 0.03 pu range between 0.87 pu and 0.9 pu is the hysteresis interval, which is related to the grid impedance. Theoretically, this hysteresis interval is directly proportional to the grid impedance.

[0052] Furthermore, according to exemplary embodiments of the present disclosure, a computer-readable storage medium is also provided having a computer program stored thereon, which, when executed, implements the low-voltage ride-through detection method according to exemplary embodiments of the present disclosure.

[0053] In an exemplary embodiment of this disclosure, the computer-readable storage medium may carry one or more programs that, when executed, perform the following steps: determining an adjustment value for a preset parameter of the power grid based on the power grid voltage; adjusting the preset parameter of the power grid based on the adjustment value; and detecting whether the power grid meets the low-voltage ride-through condition based on the power grid voltage after the preset parameter has been adjusted.

[0054] Computer-readable storage media can be, for example, but not limited to, electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatuses, or devices, or any combination thereof. More specific examples of computer-readable storage media may include, but are not limited to: electrical connections having one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. In embodiments of this disclosure, a computer-readable storage medium can be any tangible medium that contains or stores a computer program that can be used by or in conjunction with an instruction execution system, apparatus, or device. The computer program contained on the computer-readable storage medium can be transmitted using any suitable medium, including but not limited to: wires, optical cables, RF (radio frequency), etc., or any suitable combination thereof. A computer-readable storage medium can be included in any apparatus; it can also exist independently without being assembled into that apparatus.

[0055] Furthermore, according to exemplary embodiments of the present disclosure, a computer program product is also provided, wherein the instructions in the computer program product are executable by a processor of a computer device to perform a low-voltage ride-through detection method according to exemplary embodiments of the present disclosure.

[0056] The above has been combined Figure 1 and Figure 2 A low-voltage ride-through detection method according to exemplary embodiments of the present disclosure has been described. Hereinafter, reference will be made to... Figure 3 A low-voltage ride-through detection apparatus and its components according to exemplary embodiments of the present disclosure will be described.

[0057] Figure 3 A block diagram of a low-voltage ride-through detection device according to an exemplary embodiment of the present disclosure is shown.

[0058] Reference Figure 3 The low-voltage ride-through detection device includes an adjustment value determination unit 31, a parameter adjustment unit 32, and a low-voltage ride-through detection unit 33. In an exemplary embodiment of this disclosure, the low-voltage ride-through detection device may be installed in the converter controller of a wind turbine generator set.

[0059] The adjustment value determination unit 31 is configured to determine the adjustment value of the preset parameters of the power grid based on the grid voltage.

[0060] In exemplary embodiments of this disclosure, preset parameters may include current, current frequency, and power factor angle.

[0061] In an exemplary embodiment of this disclosure, the adjustment value determination unit 31 may be configured to: acquire the Q-axis component of the grid voltage; and calculate the active current limit value output by the wind turbine generator based on the Q-axis component of the grid voltage.

[0062] In an exemplary embodiment of this disclosure, the adjustment value determination unit 31 may be configured to calculate the Q-axis component of the grid voltage via a converter phase-locked loop.

[0063] In an exemplary embodiment of this disclosure, the adjustment value determination unit 31 may be configured to: filter the Q-axis component of the grid voltage; and calculate the active current limit value output by the wind turbine generator based on the processed Q-axis component.

[0064] In an exemplary embodiment of this disclosure, the adjustment value determination unit 31 may be configured to: calculate the Q-axis component of the grid voltage through the converter phase-locked loop; filter the Q-axis component of the grid voltage; and calculate the active current limit value output by the wind turbine generator based on the processed Q-axis component.

[0065] In an exemplary embodiment of this disclosure, the adjustment value determination unit 31 may be configured to perform low-pass filtering on the active current limiting value using a variable rate filtering method.

[0066] In an exemplary embodiment of this disclosure, the adjustment value determination unit 31 may be configured to: calculate the apparent current output by the wind turbine generator based on the processed Q-axis component and the rated grid-connected apparent current of the wind turbine generator set; and calculate the active current limit value output by the wind turbine generator based on the apparent current output by the wind turbine generator set.

[0067] The parameter adjustment unit 32 is configured to adjust the preset parameters of the power grid based on the adjustment value.

[0068] The low-voltage ride-through detection unit 33 is configured to detect whether the grid meets the low-voltage ride-through conditions based on the grid voltage after the preset parameters of the grid have been adjusted.

[0069] In an exemplary embodiment of this disclosure, the low-voltage ride-through detection unit 33 may be configured to: acquire the D-axis and Q-axis components of the grid voltage after the preset parameters of the grid are adjusted; calculate the vector sum of the D-axis and Q-axis components of the grid voltage after the preset parameters are adjusted to obtain the positive-sequence voltage amplitude of the grid voltage after the preset parameters are adjusted; perform low-pass filtering on the positive-sequence voltage amplitude; and detect whether the grid meets the low-voltage ride-through conditions based on the processed positive-sequence voltage amplitude and the preset low-voltage ride-through threshold.

[0070] In an exemplary embodiment of this disclosure, the low-voltage ride-through detection unit 33 may be configured to: calculate the difference between a preset low-voltage ride-through threshold and the processed positive-sequence voltage amplitude; input the difference to a hysteresis controller; when the difference is greater than the hysteresis controller's entry hysteresis value, a delay counter starts counting, and when the count value of the delay counter reaches the target delay, it is determined that the power grid meets the low-voltage ride-through condition; when the difference is less than the hysteresis controller's exit hysteresis value, a delay counter starts counting, and when the count value of the delay counter reaches the target delay, it is determined that the power grid does not meet the low-voltage ride-through condition.

[0071] The above has been combined Figure 3 A low-voltage ride-through detection apparatus according to exemplary embodiments of the present disclosure has been described. Next, in conjunction with... Figure 4 A computing device according to exemplary embodiments of the present disclosure will be described.

[0072] Figure 4 A schematic diagram of a computing device according to an exemplary embodiment of the present disclosure is shown.

[0073] Reference Figure 4 The computing device 4 according to an exemplary embodiment of the present disclosure includes a memory 41 and a processor 42. The memory 41 stores a computer program that, when executed by the processor 42, implements a low-voltage ride-through detection method according to an exemplary embodiment of the present disclosure.

[0074] In an exemplary embodiment of this disclosure, when the computer program is executed by the processor 42, the following steps can be implemented: determining an adjustment value for a preset parameter of the power grid based on the power grid voltage, wherein the preset parameter includes at least one of current, current frequency, and power factor angle; adjusting the preset parameter of the power grid based on the adjustment value; and detecting whether the power grid meets the low voltage ride-through condition based on the power grid voltage after the preset parameter of the power grid has been adjusted.

[0075] Figure 4 The computing device shown is merely an example and should not be construed as limiting the functionality and scope of use of the embodiments disclosed herein.

[0076] The above has been referred to Figures 1 to 4 A low-voltage ride-through detection method and apparatus according to exemplary embodiments of the present disclosure are described. However, it should be understood that: Figure 3 The low-voltage ride-through detection device and its units shown can be configured as software, hardware, firmware, or any combination thereof to perform specific functions. Figure 4 The computing device shown is not limited to the components shown above, but some components may be added or removed as needed, and the above components may also be combined.

[0077] The low-voltage ride-through detection method and apparatus according to exemplary embodiments of this disclosure first determine adjustment values ​​for preset parameters of the power grid based on the grid voltage, wherein the preset parameters include at least one of current, current frequency, and power factor angle. The preset parameters of the power grid are adjusted based on the adjustment values. Then, the grid voltage after the preset parameters are adjusted is used to detect whether the power grid meets the low-voltage ride-through conditions. This enables wind turbines to accurately identify grid faults under weak grid conditions and enter low-voltage ride-through mode, thus avoiding system instability during grid fault ride-through under weak grid conditions. The low-voltage ride-through detection method and apparatus according to exemplary embodiments of this disclosure greatly promote the development of wind farms in conjunction with ultra-high voltage transmission lines and large-scale power bases.

[0078] Although this disclosure has been specifically shown and described with reference to exemplary embodiments thereof, those skilled in the art should understand that various changes in form and detail may be made therein without departing from the spirit and scope of this disclosure as defined by the claims.

Claims

1. A low voltage ride through detection method, characterized in that, The method includes: When the wind turbine is connected to the grid, the adjustment values ​​of preset parameters of the grid are determined based on the grid voltage. The grid is a weak grid. The preset parameters include at least one of current, current frequency and power factor angle. The preset parameters of the power grid are adjusted based on the adjustment value to reduce the impedance voltage drop of the power grid; and Based on the grid voltage after the preset parameters of the grid have been adjusted, it is detected whether the grid meets the low voltage ride-through condition.

2. The method of claim 1, wherein, The steps for determining the adjustment values ​​of preset parameters of the power grid based on the grid voltage include: The Q-axis component of the grid voltage is calculated using the converter phase-locked loop; Filtering of the Q-axis component of the grid voltage; and The active current limit value of the wind turbine output is calculated based on the processed Q-axis component.

3. The method of claim 2, wherein, The steps for calculating the active current limit value of the wind turbine output based on the processed Q-axis component include: The apparent current output by the wind turbine is calculated based on the processed Q-axis component and the rated grid-connected apparent current of the wind turbine generator set; and The active current limit value of the wind turbine output is calculated based on the apparent current output of the wind turbine.

4. The method according to any one of claims 1 to 3, characterized in that, The steps for detecting whether the power grid meets the low-voltage ride-through conditions based on the power grid voltage after the preset parameters of the power grid have been adjusted include: Obtain the D-axis and Q-axis components of the grid voltage after the preset parameters of the grid have been adjusted. Calculate the vector sum of the D-axis and Q-axis components of the grid voltage to obtain the positive-sequence voltage amplitude of the grid voltage; Low-pass filtering is applied to the positive sequence voltage amplitude; and The system detects whether the power grid meets the low-voltage ride-through conditions based on the processed positive sequence voltage amplitude and the preset low-voltage ride-through threshold.

5. The method of claim 4, wherein, The steps for detecting whether the power grid meets the low-voltage ride-through conditions based on the processed positive-sequence voltage amplitude and the preset low-voltage ride-through threshold include: Calculate the difference between the preset low-pass threshold and the processed positive-sequence voltage amplitude; The difference is input into the hysteresis controller; When the difference is greater than the hysteresis threshold of the hysteresis controller, the delay counter starts counting, and when the count value of the delay counter reaches the target delay, it is determined that the power grid meets the low-voltage ride-through condition; and When the difference is less than the exit hysteresis value of the hysteresis controller, the delay counter starts counting, and when the count value of the delay counter reaches the target delay, it is determined that the power grid does not meet the low voltage ride-through condition.

6. A low voltage ride through detection device characterized by, The device includes: The adjustment value determination unit is configured to determine the adjustment value of preset parameters of the power grid based on the grid voltage when the wind turbine is connected to the power grid, wherein the power grid is a weak grid, and the preset parameters include at least one of current, current frequency and power factor angle. A parameter adjustment unit is configured to adjust the preset parameters of the power grid based on the adjustment value to reduce the impedance voltage drop of the power grid; and The low-voltage ride-through detection unit is configured to detect whether the power grid meets the low-voltage ride-through conditions based on the power grid voltage after the preset parameters of the power grid have been adjusted.

7. The apparatus of claim 6, wherein, The adjustment value determination unit is configured as follows: The Q-axis component of the grid voltage is calculated using the converter phase-locked loop; The Q-axis component of the grid voltage is filtered. The active current limit value of the wind turbine output is calculated based on the processed Q-axis component.

8. The apparatus of claim 6 or 7, wherein, The low-penetration detection unit is configured as follows: Obtain the D-axis and Q-axis components of the grid voltage after the preset parameters of the grid have been adjusted. Calculate the vector sum of the D-axis and Q-axis components of the grid voltage to obtain the positive-sequence voltage amplitude of the grid voltage; The positive sequence voltage amplitude is low-pass filtered. The system detects whether the power grid meets the low-voltage ride-through conditions based on the processed positive sequence voltage amplitude and the preset low-voltage ride-through threshold.

9. The apparatus of claim 8, wherein, The low-penetration detection unit is configured as follows: Calculate the difference between the preset low-pass threshold and the processed positive-sequence voltage amplitude; The difference is input into the hysteresis controller; When the difference is greater than the hysteresis value of the hysteresis controller, the delay counter starts counting, and when the count value of the delay counter reaches the target delay, it is determined that the power grid meets the low voltage ride-through condition. When the difference is less than the exit hysteresis value of the hysteresis controller, the delay counter starts counting, and when the count value of the delay counter reaches the target delay, it is determined that the power grid does not meet the low voltage ride-through condition.

10. The apparatus of claim 8, wherein, The device is installed in the converter controller of the wind turbine generator set.

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