Alternating current fault ride-through control method and device of network-forming type wind generating set

Abstract

The invention relates to an alternating-current fault ride-through control method and device for a grid-forming type wind generating set. The wind generating set is arranged in a direct-current power transmission system based on a diode rectification unit, and the method comprises the steps that a voltage error value is determined based on a measured value and a reference value of output voltage of a converter of the wind generating set, and the reference value of the output voltage is an alternating-current side rated voltage amplitude of the diode rectification unit; adjusting an active power reference value and a reference frequency and a frequency measurement value of the output voltage based on the voltage error value; and performing active power control on the wind generating set based on the adjusted active power reference value, and performing frequency control on the wind generating set based on the adjusted reference frequency and the frequency measurement value. By adopting the method and the device, whether the fan enters the fault ride-through strategy or not can be determined by adopting the local information voltage amplitude without additional fault information, and the fault current of the converter can be reduced.

Description

Technical Field

[0001] The present disclosure relates to the technical field of wind power generation, and more particularly, to an AC fault ride-through control method and device for a grid-forming wind turbine generator set. Background Art

[0002] With the rapid development of high-voltage direct current (HVDC) technology based on voltage source converters (VSCs), offshore wind power will play an important role in the power market. To reduce the cost of offshore wind power generation systems, HVDC based on diode rectifier units (DRU-HVDC) has received significant attention in recent years. Replacing the traditional offshore rectifier (e.g., VSC) with a diode rectifier unit can not only significantly reduce transmission losses and the total cost, but also significantly increase the transmission capacity. In addition, it can also significantly reduce the volume and weight of the platform. Moreover, the diode rectifier unit also has advantages such as high reliability, modular design, full encapsulation, and low operation and maintenance costs. Summary of the Invention

[0003] The present disclosure provides an AC fault ride-through control method and device for a grid-forming wind turbine generator set, a grid-forming wind turbine generator set, an offshore wind power transmission system, a computing system, and a computer-readable storage medium.

[0004] According to one aspect of the present disclosure, there is provided an AC fault ride-through control method for a grid-forming wind turbine generator set, the wind turbine generator set being disposed in a DC power transmission system based on a diode rectifier unit, the AC fault ride-through control method including: determining a voltage error value based on a measured value and a reference value of the output voltage of a converter of the wind turbine generator set, wherein the reference value of the output voltage is the rated voltage amplitude of the AC side of the diode rectifier unit; adjusting a reference value of the active power, as well as the reference frequency and the measured frequency of the output voltage, based on the voltage error value; performing active power control on the wind turbine generator set based on the adjusted reference value of the active power, and performing frequency control on the wind turbine generator set based on the adjusted reference frequency and the measured frequency.

[0005] Optionally, the measured value of the output voltage of the converter of the wind turbine generator set is the actual measured value of the d-axis of the output voltage, and the voltage error value is the difference between the rated voltage amplitude of the AC side and the actual measured value of the d-axis.

[0006] Optionally, the step of adjusting the active power reference value based on the voltage error value includes: in response to the voltage error value being less than a first threshold, setting the active power reference value to a first power value greater than zero; in response to the voltage error value being greater than the first threshold and less than a second threshold, reducing the active power reference value from the first power value to a second power value at a first predetermined slope; in response to the voltage error value being greater than the second threshold, setting the active power reference value to zero, and reducing the voltage feedforward value at a second predetermined slope to reduce the reference value of the output voltage.

[0007] Optionally, the first threshold and the second threshold are determined based on the rated voltage of the filter capacitor of the converter of the wind turbine generator.

[0008] Optionally, the first predetermined slope and the second predetermined slope are determined based on the first threshold and the second threshold.

[0009] Optionally, the step of adjusting the reference frequency and the frequency measurement value of the output voltage based on the voltage error value includes: in response to the voltage error value being less than the first threshold, setting the reference frequency to a first reference frequency value; in response to the voltage error value being greater than the first threshold and less than the second threshold, reducing the reference frequency from the first reference frequency value to a second reference frequency value at a third predetermined slope, and reducing the frequency feedforward value at a fourth predetermined slope to reduce the frequency measurement value; in response to the voltage error value being greater than the second threshold, setting the reference frequency to zero.

[0010] Optionally, the third predetermined slope and the fourth predetermined slope are determined based on the first threshold and the second threshold.

[0011] According to an aspect of the present disclosure, there is provided an AC fault ride-through control device for a grid-forming wind turbine generator, the wind turbine generator being disposed in a DC power transmission system based on a diode rectifier unit, the AC fault ride-through control device including: a voltage error determination unit configured to determine a voltage error value based on a measured value and a reference value of the output voltage of a converter of the wind turbine generator, wherein the reference value of the output voltage is the rated voltage amplitude of the AC side of the diode rectifier unit; a parameter adjustment unit configured to adjust the active power reference value and the reference frequency and the frequency measurement value of the output voltage based on the voltage error value; an active power and frequency control unit configured to perform active power control on the wind turbine generator based on the adjusted active power reference value, and perform frequency control on the wind turbine generator based on the adjusted reference frequency and the frequency measurement value.

[0012] Optionally, the measured value of the output voltage of the converter of the wind turbine generator set is the actual measured value of the d-axis of the output voltage, and the voltage error value is the difference between the rated voltage amplitude of the AC side and the actual measured value of the d-axis.

[0013] Optionally, the parameter adjustment unit is configured to: in response to the voltage error value being less than a first threshold, set the active power reference value to a first power value greater than zero; in response to the voltage error value being greater than the first threshold and less than a second threshold, reduce the active power reference value from the first power value to a second power value at a first predetermined slope; in response to the voltage error value being greater than the second threshold, set the active power reference value to zero, and reduce the voltage feedforward value at a second predetermined slope to reduce the reference value of the output voltage.

[0014] Optionally, the first threshold and the second threshold are determined based on the rated voltage of the filter capacitor of the converter of the wind turbine generator set.

[0015] Optionally, the first predetermined slope and the second predetermined slope are determined based on the first threshold and the second threshold.

[0016] Optionally, the parameter adjustment unit is configured to: in response to the voltage error value being less than the first threshold, set the reference frequency to a first reference frequency value; in response to the voltage error value being greater than the first threshold and less than the second threshold, reduce the reference frequency from the first reference frequency value to a second reference frequency value at a third predetermined slope, and reduce the frequency feedforward value at a fourth predetermined slope to reduce the frequency measurement value; in response to the voltage error value being greater than the second threshold, set the reference frequency to zero.

[0017] Optionally, the third predetermined slope and the fourth predetermined slope are determined based on the first threshold and the second threshold.

[0018] According to one aspect of the present disclosure, there is provided a grid-forming wind turbine generator set, which includes a controller configured to execute the AC fault ride-through control method of the grid-forming wind turbine generator set as described above.

[0019] According to one aspect of the present disclosure, there is provided an offshore wind power transmission system, which includes: a plurality of grid-forming wind turbine generator sets connected in parallel to each other; a step-up transformer, the primary side of which is connected to the output terminals of the plurality of grid-forming wind turbine generator sets; and a diode rectification unit connected to the secondary side of the step-up transformer and outputting high-voltage direct current, wherein each grid-forming wind turbine generator set includes a controller configured to execute the AC fault ride-through control method of the grid-forming wind turbine generator set as described above.

[0020] Optionally, the output end of the converter of each grid-forming wind turbine generator is connected to the primary side of the fan transformer of the corresponding grid-forming wind turbine generator via a first common connection point.

[0021] Optionally, the secondary side of the fan transformer of each grid-forming wind turbine generator is connected to the primary side of the step-up transformer via a second common connection point.

[0022] According to one aspect of the present disclosure, there is provided a computing system including at least one computing device and at least one storage device storing instructions, which when run by the at least one computing device, cause the at least one computing device to execute the AC fault ride-through control method of the grid-forming wind turbine generator as described above.

[0023] According to one aspect of the present disclosure, there is provided a computer-readable storage medium storing instructions, which when run by at least one computing device, cause the at least one computing device to execute the AC fault ride-through control method of the grid-forming wind turbine generator as described above.

[0024] By adopting the present disclosure, it is possible to use the local information voltage amplitude to determine whether the local fan enters the fault ride-through strategy without additional fault information; it is possible to perform adaptive control based on the local voltage information to reduce the converter fault current, ensure timely removal of the faulty converter and keep the non-faulty converter running continuously. Description of the Drawings

[0025] By describing the embodiments with reference to the drawings below, the above and / or other objects and advantages of the present disclosure will become clearer, where:

[0026] Figure 1 is a flowchart showing the AC fault ride-through control method of the grid-forming wind turbine generator according to an exemplary embodiment of the present disclosure;

[0027] Figure 2 is a block diagram showing the control strategy of the grid-forming wind turbine generator according to the prior art;

[0028] Figure 3 is a block diagram showing the power adaptive control according to an exemplary embodiment of the present disclosure;

[0029] Figure 4 is a block diagram showing the frequency adaptive control according to an exemplary embodiment of the present disclosure;

[0030] Figure 5 is a schematic diagram showing the offshore wind power transmission system according to an exemplary embodiment of the present disclosure;

[0031] Figure 6It is a schematic diagram showing fault detection for a single - machine fault according to an exemplary embodiment of the present disclosure;

[0032] Figure 7A It is a curve graph showing the voltage and current at PCC1 of a faulty wind turbine in the case of a single - machine fault when the adaptive control according to the present disclosure is not added;

[0033] Figure 7B It is a curve graph showing the voltage and current at PCC1 of a faulty wind turbine in the case of a single - machine fault when the adaptive control according to the present disclosure is added;

[0034] Figure 8A It is a curve graph showing the power at PCC1 of a faulty wind turbine in the case of a single - machine fault when the adaptive control according to the present disclosure is not added;

[0035] Figure 8B It is a curve graph showing the power at PCC1 of a faulty wind turbine in the case of a single - machine fault when the adaptive control according to the present disclosure is added;

[0036] Figure 9A It is a curve graph showing the voltage and current at PCC1 of a non - faulty wind turbine in the case of a single - machine fault when the adaptive control according to the present disclosure is not added;

[0037] Figure 9B It is a curve graph showing the voltage and current at PCC1 of a non - faulty wind turbine in the case of a single - machine fault when the adaptive control according to the present disclosure is added;

[0038] Figure 10A It is a curve graph showing the power at PCC1 of a non - faulty wind turbine in the case of a single - machine fault when the adaptive control according to the present disclosure is not added;

[0039] Figure 10B It is a curve graph showing the power at PCC1 of a non - faulty wind turbine in the case of a single - machine fault when the adaptive control according to the present disclosure is added;

[0040] Figure 11A It is a curve graph showing the voltage and current at PCC2 in the case of a single - machine fault when the adaptive control according to the present disclosure is not added;

[0041] Figure 11B It is a curve graph showing the voltage and current at PCC2 in the case of a single - machine fault when the adaptive control according to the present disclosure is added;

[0042] Figure 12A It is a curve graph showing the power at PCC2 in the case of a single - machine fault when the adaptive control according to the present disclosure is not added;

[0043] Figure 12B is a graph showing the power at PCC2 in the case of a single machine fault when the adaptive control according to the present disclosure is added;

[0044] Figure 13 is a schematic diagram showing the detection of a fault at PCC2 according to an exemplary embodiment of the present disclosure;

[0045] Figure 14A is a graph showing the voltage and current of a single wind turbine in the case of a fault at PCC2 when the adaptive control according to the present disclosure is not added;

[0046] Figure 14B is a graph showing the voltage and current of a single wind turbine in the case of a fault at PCC2 when the adaptive control according to the present disclosure is added;

[0047] Figure 15A is a graph showing the power of a single wind turbine in the case of a fault at PCC2 when the adaptive control according to the present disclosure is not added;

[0048] Figure 15B is a graph showing the power of a single wind turbine in the case of a fault at PCC2 when the adaptive control according to the present disclosure is added;

[0049] Figure 16A is a graph showing the frequency of the converter in the case of a fault at PCC2 when the adaptive control according to the present disclosure is not added;

[0050] Figure 16B is a graph showing the frequency of the converter in the case of a fault at PCC2 when the adaptive control according to the present disclosure is added;

[0051] Figure 17A is a graph showing the voltage and current at PCC2 in the case of a fault at PCC2 when the adaptive control according to the present disclosure is not added;

[0052] Figure 17B is a graph showing the voltage and current at PCC2 in the case of a fault at PCC2 when the adaptive control according to the present disclosure is added;

[0053] Figure 18A is a graph showing the power at PCC2 in the case of a fault at PCC2 when the adaptive control according to the present disclosure is not added;

[0054] Figure 18BIt is a graph showing the power at PCC2 in the case of a fault at PCC2 when the adaptive control according to the present disclosure is added;

[0055] Figure 19A It is a graph showing the DC-side power of the DRU in the case of a fault at PCC2 when the adaptive control according to the present disclosure is not added;

[0056] Figure 19B It is a graph showing the DC-side power of the DRU in the case of a fault at PCC2 when the adaptive control according to the present disclosure is added;

[0057] Figure 20 It is a block diagram showing an AC fault ride-through control device of a network-forming wind turbine according to an exemplary embodiment of the present disclosure;

[0058] Figure 21 It is a block diagram showing a computing system according to an exemplary embodiment of the present disclosure, including at least one computing device and at least one storage device storing instructions. Detailed implementation manners

[0059] The following provides a description of the detailed implementation manners in conjunction with the accompanying drawings to help the reader obtain a comprehensive understanding of the methods, devices, and / or systems described herein. However, various changes, modifications, and equivalents of the methods, devices, and / or systems described herein will be apparent after understanding the disclosure of the present application. For example, the order of operations described herein is merely exemplary and is not limited to those set forth herein, but may be changed as will be apparent after understanding the disclosure of the present application, except for operations that must occur in a specific order. In addition, descriptions of features known in the art may be omitted for greater clarity and conciseness.

[0060] In the case of using a diode rectifier unit (DRU) as the rectifier for long-distance power transmission, the traditional fault ride-through strategy will no longer be applicable to the current system. Due to the change in the control strategy of the rectifier on the grid side of the wind turbine, the traditional p-f, q-v rectifier fault control strategy cannot meet the new rectifier correspondence p-v, q-f brought by the DRU. Therefore, the present disclosure proposes a fault ride-through control strategy after an AC fault of a wind turbine (such as a two-phase short circuit or a three-phase short circuit fault of the submarine cable on the outlet side of the wind turbine generator set), so as to meet the requirements of voltage stability and frequency stability on the AC side.

[0061] Figure 1 It is a flowchart showing an AC fault ride-through control method of a network-forming wind turbine according to an exemplary embodiment of the present disclosure. Figure 2 It is a block diagram showing the control strategy of a network-forming wind turbine according to the prior art. Figure 3is a block diagram showing power adaptive control according to an exemplary embodiment of the present disclosure. Figure 4 is a block diagram showing frequency adaptive control according to an exemplary embodiment of the present disclosure.

[0062] In the voltage loop and current loop of the grid-forming wind turbine generator set control according to the prior art as Figure 2 shown, the d-axis reference of the voltage comes from the active power control loop, mainly determining the amplitude of the converter (or called inverter) output voltage, and the q-axis reference of the voltage comes from the frequency control loop, mainly determining the phase of the output voltage. In order to achieve rated frequency operation, avoid satellite communication and achieve local operation, a phase-locked loop is used to participate in the control loop to obtain the feedback of the frequency. At the same time, in order to avoid generating reactive current circulation, two current circulation controllers are used for compensation control.

[0063] Regarding current control, the current inner loop has the advantages of fast response and current limiting in the event of an external AC fault. The dynamic representation of the VSC current loop in the dq coordinate system where the q-axis component U F of the VSC filter bus voltage is approximately 0 is:

[0064]

[0065]

[0066] where L is the filter inductance, ω is the frequency of the dq reference coordinate system controlled by the converter. U C and U F represent the AC side voltage of the wind turbine converter and the filter capacitor voltage. I W is the AC side current of the converter. The variable subscripts d and q represent the d-axis component and q-axis component of the corresponding variables respectively.

[0067] Regarding voltage control, as Figure 2 shown, the voltage dynamic description of the grid-side converter of the wind turbine generator set in the dq coordinate system is:

[0068]

[0069]

[0070] By adjusting the output current of the converter, the voltage U F at the VSC filter capacitor can be controlled to follow its reference value, and the output dq current limit is set according to the converter current rating. Where C is the filter capacitor, ω is the frequency of the dq reference coordinate system controlled by the converter. I W and I S represent the AC side current of the wind turbine converter and the valve side current of the wind turbine transformer. U Fis the filter capacitor voltage at the converter outlet side. The variable subscripts d and q represent the d-axis component and q-axis component of the corresponding variable.

[0071] Regarding the active power control, since the onshore MMC controls the DC voltage of the DRU link at the rated value, the transmitted active power is largely determined by the DC voltage generated by the diode rectifier. By changing U Fdref so as to finally achieve the static error-free control of the active power. Therefore, the active control loop can be expressed as:

[0072]

[0073] where, P ref is the wind turbine power reference value calculated by the wind turbine using the maximum power tracking control algorithm according to the current impeller rotational angular velocity. P s is the actual output power of the wind turbine. K pp and K pi are the proportional coefficient and integral coefficient of the active control loop respectively. U Fdref represents the d-axis voltage reference value.

[0074] Regarding the phase-locked loop (PLL) control, in order to make the offshore grid voltage generated by the voltage loop control have a fixed voltage frequency, a frequency control link needs to be designed to control the voltage frequency and phase. In order not to use satellite communication, the PLL will play a key role in the localized frequency control. The purpose of the PLL is to obtain the local frequency and phase of the converter output in a timely manner. The PLL takes U Fq as the input, adjusts the frequency output, and ensures that the q-axis voltage U Fq is zero. If the measured U Fq is slightly greater than zero, the detected frequency of the voltage vector will increase.

[0075] ω t =K lp U Fq +K li ∫U Fq dt + ω0 (6)

[0076] where: ω0 is the reference frequency (for example, 20Hz), ω t is the actual frequency, U Fq represents the q-axis component of the filter capacitor voltage on the AC side of the wind turbine converter, and K lp and K li are the proportional coefficient and integral coefficient of the PLL control loop respectively.

[0077] In grid-forming control, there is no angular frequency supported by a strong grid. The angular frequency of the offshore wind farm is completely generated by the wind farm itself. Therefore, setting the q-axis to zero is no longer appropriate. Since the local frequency and phase angle measured by the PLL reflect the output U of the offshore AC network converter Fq , this indicates that the q-axis voltage reference U Fqref can be used to control the AC frequency. Therefore, a PLL-based frequency loop is used to generate the required U Fqref . The PLL loop can generate a frequency quantity to adjust U Fq to achieve the generation of a specific U Fq voltage demand. Therefore, it can be realized that the generation of U Fq satisfies the tracking of a specific frequency. Since the main purpose of the grid-forming wind turbine is to construct a stable low-frequency AC network at the PCC point, the frequency control link adopts a non-static error control method. The control method of non-static error control is expressed as:

[0078] U Fqref = K fp (ω ref - ω t ) + K fi ∫(ω ref - ω t )dt(7)

[0079] Where: ω ref is the reference frequency, ω t is the actual frequency, K fp is the proportional coefficient of the frequency control loop, K fi is the integral coefficient of the frequency control loop, and U Fqref represents the q-axis reference value of the voltage.

[0080] To maintain the reactive power balance of the entire system, ω ref needs to be adjusted through the reactive power control link to maintain dynamic reactive power balance and frequency stability. Since no dynamic reactive power compensation equipment such as static var generators (SVG) is installed, the reactive power output of the offshore wind farm is determined by the active power output. Therefore, it is necessary to first compensate the reactive power output at the rated active power output to 0 through passive equipment. Since each converter uses a local phase-locked loop for local phase-locking and obtains different reference phases, reactive power control will be used to adjust the rated speed ω of the entire wind farm ref .

[0081] The AC fault ride-through control method of the grid-forming wind turbine according to the exemplary embodiment of the present disclosure includes power adaptive control and frequency adaptive control as shown in Figure 3 and Figure 4 . Figure 3 and Figure 4 The parts within the dashed boxes in Figure 2The differences in the grid-forming wind turbine control are as follows. Refer to the following Figure 1 , Figure 3 and Figure 4 to specifically describe the AC fault ride-through control method for a grid-forming wind power generation unit according to an exemplary embodiment of the present disclosure.

[0082] In the example, the grid-forming wind power generation unit is arranged in a DC power transmission system based on a diode rectifier unit. As Figure 1 shown, in step S101, based on the measured value and the reference value of the output voltage of the converter of the wind power generation unit, a voltage error value is determined, where the reference value of the output voltage of the converter of the wind power generation unit is the rated voltage amplitude of the AC side of the diode rectifier unit. In the example, the measured value of the output voltage of the converter of the wind power generation unit is the actual measured value of the d-axis of the output voltage of the converter of the wind power generation unit, and the voltage error value is the difference between the rated voltage amplitude of the AC side of the diode rectifier unit and the actual measured value of the d-axis of the output voltage of the converter of the wind power generation unit.

[0083] For example, by measuring the voltage amplitude of the AC side port of the local wind turbine and comparing it with the rated AC voltage amplitude when the DRU is conducting, it can be determined whether the converter of the wind turbine is connected to the DRU and conducting. Since in the grid-forming control converter, the amplitude of the AC voltage is controlled by U fd , the judgment signal based on the voltage error is as follows:

[0084] U Fdref -U Fd = ERROR (8)

[0085] where, U Fd represents the actual measured value of the d-axis of the output voltage of the local wind turbine converter (for example, the voltage of the AC side filter capacitor at the output of the wind turbine inverter), U Fdref represents the rated voltage amplitude of the AC side when the DRU is conducting, and ERROR represents the voltage error value. The ERROR value is different for each wind turbine converter depending on the fault occurrence point and the fault depth.

[0086] In step S102, based on the voltage error value, the reference value of the active power and the reference frequency and the measured frequency of the output voltage of the converter of the wind power generation unit are adjusted. In the example, in response to the voltage error value being less than the first threshold, the reference value of the active power is set to a first power value greater than zero; in response to the voltage error value being greater than the first threshold and less than the second threshold, the reference value of the active power is decreased from the first power value to the second power value at a first predetermined slope; in response to the voltage error value being greater than the second threshold, the reference value of the active power is set to zero, and the voltage feedforward value is decreased at a second predetermined slope to reduce the reference value of the output voltage of the converter of the wind power generation unit.

[0087] In the example, the first threshold and the second threshold are determined based on the rated voltage of the filter capacitor of the converter of the wind turbine generator. For example, the first threshold is equal to 1.1 times the rated voltage of the filter capacitor of the converter of the wind turbine generator, and the second threshold is equal to 1.3 times the rated voltage of the filter capacitor of the converter of the wind turbine generator. It should be understood that 1.1 times or 1.3 times the rated voltage of the filter capacitor of the converter of the wind turbine generator here is only an example, and the multiples of the first threshold and the second threshold to the rated voltage of the filter capacitor of the converter of the wind turbine generator can also be other values (for example, 1.0, 1.4, etc.). In the example, the first predetermined slope and the second predetermined slope are determined based on the first threshold and the second threshold. For example, the first predetermined slope and the second predetermined slope can be equal to the opposite of the reciprocal of the difference between the second threshold and the first threshold.

[0088] For example, a power adaptive controller is designed according to the voltage error value ERROR, and the power adaptive control rate is:

[0089]

[0090] where error1 and error2 are 1.1 times and 1.3 times the rated voltage of the filter capacitor of the converter of the wind turbine generator respectively.

[0091] When the voltage error value ERROR is less than error1, the active power reference value remains the current value unchanged; when the voltage error value ERROR is greater than error1 and less than error2, the active power reference value starts to decrease with a slope of K; when the voltage error value ERROR is greater than error2, the active power reference value is directly reduced to 0, and the voltage feedforward value U0 is decreased with a predetermined slope. Among them, the slope K can be expressed as:

[0092]

[0093] For example, referring to Figure 3 , when the voltage error value ERROR is less than error1, the energy-consuming circuit (for example, a circuit including an energy-consuming resistor) and the power adaptive module are both disconnected, that is, the corresponding switches are switched to K2 and K4; when the voltage error value ERROR is greater than error1 and less than error2, the corresponding switches are switched to K2 and K3 to access the power adaptive module; when the voltage error value ERROR is greater than error2, the active power reference value is set to 0, and the switch is switched to K1 to use the energy-consuming circuit to decrease the voltage feedforward value U0 with a predetermined slope.

[0094] In the example, in response to the voltage error value being less than the first threshold, the reference frequency of the output voltage of the converter of the wind turbine generator set is set to the first reference frequency value; in response to the voltage error value being greater than the first threshold and less than the second threshold, the reference frequency of the output voltage of the converter of the wind turbine generator set is decreased from the first reference frequency value to the second reference frequency value at a third predetermined slope, and the frequency feedforward value is decreased at a fourth predetermined slope to decrease the frequency measurement value of the output voltage of the converter of the wind turbine generator set; in response to the voltage error value being greater than the second threshold, the reference frequency of the output voltage of the converter of the wind turbine generator set is set to zero. In the example, the third predetermined slope and the fourth predetermined slope are determined based on the first threshold and the second threshold. For example, the third predetermined slope and the fourth predetermined slope can be determined based on the method of determining the slope K described above. Thereby, the frequency provided by the wind turbine generator set during an AC fault can be adjusted, and the magnitude of the current on the DC side in the converter of the direct-drive generator set can be adjusted quickly.

[0095] For example, referring to Figure 4 , when the voltage error value ERROR is less than error1, the corresponding switches in the reactive power distribution control and the PLL control are respectively switched to K6 and K8 to maintain the existing reference frequency value. When the voltage error value ERROR is greater than error1 and less than error2, the corresponding switches in the reactive power distribution control and the PLL control are respectively switched to K5 and K7 to decrease the reference frequency of the output voltage of the converter of the wind turbine generator set from the first reference frequency value to the second reference frequency value at a predetermined slope, and the frequency feedforward value is decreased at a predetermined slope to decrease the frequency measurement value of the output voltage of the converter of the wind turbine generator set. When the voltage error value ERROR is greater than error2, the corresponding switches in the reactive power distribution control and the PLL control are respectively maintained at K5 and K7, and the reference frequency of the output voltage of the converter of the wind turbine generator set is set to zero. First, when the rated reactive power at the PCC point is 0 after ensuring the self-designed reactive power compensation of the wind farm, a reactive power controller is designed.

[0096] Considering that in the AC system sent out by the DRU, the synchronous frequency is a very important control target. In the normal sending control, it is expected that the frequency of the fan converter can be kept as stable as possible at the rated sending frequency. However, during a fault, since the fans at the fault location often need to be disconnected from the AC system through a circuit breaker to ensure the normal operation of other synchronous converters, the frequency maintenance of the fan converter after the fault is no longer important because no power is sent out. The frequency of the faulty fan can be decreased to reduce the reactive power impact on the converter. Therefore, for the PLL and reactive power links, adaptive control is also required to reduce the reactive current.

[0097] In step S103, active power control is performed on the wind turbine generator set based on the adjusted active power reference value, and frequency control is performed on the wind turbine generator set based on the adjusted reference frequency and the frequency measurement value. By adopting the AC fault ride-through control method for the grid-forming wind turbine generator set according to the exemplary embodiments of the present disclosure, it is possible to use the local information voltage amplitude to determine whether the wind turbine enters the fault ride-through strategy without additional fault information, reduce the converter fault current, and enable the parameters in the power transmission system to return to the normal values faster after the fault is eliminated. Moreover, through the above method, it is possible to ensure non-disconnection during the fault and continue to transmit power until the rated power of wind power generation is restored, and the above method is robust to various AC faults, such as Figures 7A to 12B and Figures 14A to 19B The simulation results shown confirm the improvement of the proposed fault protection strategy compared with the prior art.

[0098] Figure 5 is a schematic diagram showing a marine wind power transmission system according to an exemplary embodiment of the present disclosure.

[0099] In the example, the marine wind power transmission system according to the exemplary embodiment of the present disclosure includes: a plurality of grid-forming wind turbine generator sets connected in parallel with each other; a step-up transformer, the primary side of the step-up transformer being connected to the output terminals of the plurality of grid-forming wind turbine generator sets; and a diode rectifier unit connected to the secondary side of the step-up transformer and outputting high-voltage direct current, wherein each grid-forming wind turbine generator set includes a controller configured to execute the AC fault ride-through control method for the grid-forming wind turbine generator set as described above. The output terminal of the converter of each grid-forming wind turbine generator set is connected to the primary side of the fan transformer of the corresponding grid-forming wind turbine generator set via a first point of common coupling PCC1. The secondary side of the fan transformer of each grid-forming wind turbine generator set is connected to the primary side of the step-up transformer via a second point of common coupling PCC2.

[0100] For example, as Figure 5 shown, the marine wind power transmission system according to the exemplary embodiment of the present disclosure includes a plurality of grid-forming wind turbine generator sets (e.g., 11 grid-forming wind turbine generator sets) connected in parallel with each other. In Figure 5 the example shown, the wind turbine generator set is a six-phase wind turbine generator set including two back-to-back converters, and the power of each permanent magnet synchronous generator (PMSG) is 4.5 MW. In addition, as Figure 5 shown, DRUs are connected in series, and each DRU consists of two 12-pulse bridges connected in series, with a star-star-delta three-winding transformer on the AC side. It should be understood that Figure 5The illustrated wind turbine generator, DRU, and their internal connection relationships are merely examples, and the scope of the present disclosure is not limited thereto. For example, the wind turbine generator included in the offshore wind power transmission system according to the exemplary embodiments of the present disclosure may also be a three-phase wind turbine generator. In addition, in view of the uniqueness of the topological structure of the offshore wind power transmission system according to the exemplary embodiments of the present disclosure (for example, after the wind turbines are first connected in parallel and then connected to PCC2 through a wind turbine step-up), there is an internal circulating current between two locally parallel-connected wind turbines due to software asynchrony or inconsistent hardware parameters. Therefore, the internal circulating current control can be used as a feedforward quantity for frequency control to eliminate the internal phase fluctuations caused by the inconsistent parameters of the two local wind turbines. In the case of the topological structure as Figure 5 shown, it is possible to achieve the high-voltage DC power output of a six-phase wind turbine via a DRU by using a local full-network control without communication.

[0101] Figure 6 FIG. [FIGURE NUMBER] is a schematic diagram showing the fault detection for a single-machine fault according to the exemplary embodiments of the present disclosure.

[0102] As Figure 6 shown, the output terminal of the converter of the network-forming wind turbine generator is connected to the primary side of the wind turbine transformer of the corresponding network-forming wind turbine generator via the first common connection point PCC1. In the example, a three-phase symmetrical fault is introduced at a single wind turbine generator, the fault intervenes at 2 seconds, and the fault ends at 2.5 seconds. After a single wind turbine generator fails, the faulty unit is first cut out using a circuit breaker, and the remaining wind turbine generators operate normally. After the fault ends, the circuit breaker is closed again for the faulty unit to resume normal operation. The following Figures 7A to 12B shown curves are all obtained through the above test process.

[0103] Figure 7A FIG. [FIGURE NUMBER] is a graph showing the voltage and current at PCC1 of the faulty wind turbine in the case of a single-machine fault when the adaptive control according to the present disclosure is not added. Figure 7B FIG. [FIGURE NUMBER] is a graph showing the voltage and current at PCC1 of the faulty wind turbine in the case of a single-machine fault when the adaptive control according to the present disclosure is added. In Figure 7A and Figure 7B , the upper curve is the voltage curve at PCC1 of the faulty wind turbine, and the lower curve is the current curve at PCC1 of the faulty wind turbine. Comparing Figure 7A and Figure 7B it can be found that, compared with the case where the adaptive control according to the present disclosure is not added, in the case where the adaptive control according to the present disclosure is added, the recovery time of the voltage and current after fault control is faster.

[0104] Figure 8A Please note that the figure numbers in the above translation are placeholders and need to be filled in according to the actual figure numbers in the original text.It is a graph showing the power at the PCC1 of the faulty wind turbine in the case of a single-machine fault when the adaptive control according to the present disclosure is not added. Figure 8B It is a graph showing the power at the PCC1 of the faulty wind turbine in the case of a single-machine fault when the adaptive control according to the present disclosure is added. In Figure 8A and Figure 8B the upper curve is the curve of the active power at the PCC1 of the faulty wind turbine, and the lower curve is the curve of the reactive power at the PCC1 of the faulty wind turbine. Comparing Figure 8A and Figure 8B it can be found that, compared with the case where the adaptive control according to the present disclosure is not added, in the case where the adaptive control according to the present disclosure is added, after the fault is cleared, the power recovery time due to error accumulation is relatively shorter and the recovery speed is faster.

[0105] Figure 9A It is a graph showing the voltage and current at the PCC1 of the non-faulty wind turbine in the case of a single-machine fault when the adaptive control according to the present disclosure is not added. Figure 9B It is a graph showing the voltage and current at the PCC1 of the non-faulty wind turbine in the case of a single-machine fault when the adaptive control according to the present disclosure is added. In Figure 9A and Figure 9B the upper curve is the curve of the voltage at the PCC1 of the non-faulty wind turbine, and the lower curve is the curve of the current at the PCC1 of the non-faulty wind turbine. Comparing Figure 9A and Figure 9B it can be found that, compared with the case where the adaptive control according to the present disclosure is not added, in the case where the adaptive control according to the present disclosure is added, the non-faulty wind turbine is less disturbed and can still maintain the rated output.

[0106] Figure 10A It is a graph showing the power at the PCC1 of the non-faulty wind turbine in the case of a single-machine fault when the adaptive control according to the present disclosure is not added. Figure 10B It is a graph showing the power at the PCC1 of the non-faulty wind turbine in the case of a single-machine fault when the adaptive control according to the present disclosure is added. In Figure 10A and Figure 10B the upper curve is the curve of the active power at the PCC1 of the non-faulty wind turbine, and the lower curve is the curve of the reactive power at the PCC1 of the non-faulty wind turbine. Comparing Figure 10A and Figure 10B it can be found that, compared with the case where the adaptive control according to the present disclosure is not added, in the case where the adaptive control according to the present disclosure is added, the non-faulty wind turbine is less disturbed, the anti-disturbance performance of the power of the non-faulty wind turbine is better, and it is closer to the rated operating state during the fault and recovery period.

[0107] Figure 11A is a graph showing the voltage and current at PCC2 in the case of a single - machine fault when the adaptive control according to the present disclosure is not added. Figure 11B is a graph showing the voltage and current at PCC2 in the case of a single - machine fault when the adaptive control according to the present disclosure is added. In Figure 11A and Figure 11B the upper curve is the curve of the voltage at PCC2, and the lower curve is the curve of the current at PCC2. Comparing Figure 11A and Figure 11B it can be found that, compared with the case where the adaptive control according to the present disclosure is not added, in the case where the adaptive control according to the present disclosure is added, the fluctuation of the current amplitude at PCC2 is smaller, and PCC2 can recover to rated operation faster after the fault is cleared.

[0108] Figure 12A is a graph showing the power at PCC2 in the case of a single - machine fault when the adaptive control according to the present disclosure is not added. Figure 12B is a graph showing the power at PCC2 in the case of a single - machine fault when the adaptive control according to the present disclosure is added. In Figure 12A and Figure 12B the upper curve is the curve of the active power at PCC2, and the lower curve is the curve of the reactive power at PCC2. Comparing Figure 12A and Figure 12B it can be found that, compared with the case where the adaptive control according to the present disclosure is not added, in the case where the adaptive control according to the present disclosure is added, after the fault is cleared, PCC2 can recover to rated operation faster.

[0109] Figure 13 is a schematic diagram showing the detection of a fault at PCC2 according to an exemplary embodiment of the present disclosure.

[0110] As Figure 13 shown, the secondary side of the fan transformer of the grid - forming wind turbine generator is connected to the primary side of the step - up transformer via the second point of common coupling PCC2. In the example, a three - phase symmetrical fault is added at the PCC2 point, the fault intervenes at 2 seconds, and the fault ends at 2.2 seconds. The following Figures 14A to 19B shown curves are all obtained through the above - mentioned test process.

[0111] Figure 14A is a graph showing the voltage and current of a single wind turbine generator in the case of a fault at PCC2 when the adaptive control according to the present disclosure is not added. Figure 14Bis a graph showing the voltage and current of a single wind turbine in the event of a fault at PCC2 when the adaptive control according to the present disclosure is added. In Figure 14A and Figure 14B , the upper curve is the voltage curve of a single wind turbine, and the lower curve is the current curve of a single wind turbine. Comparing Figure 14A and Figure 14B it can be found that, compared with the case where the adaptive control according to the present disclosure is not added, when the adaptive control according to the present disclosure is added, the current during the fault is significantly reduced, so that the overcurrent impact on the wind turbine converter during the fault can be reduced, effectively protecting the safety of the wind turbine converter.

[0112] Figure 15A is a graph showing the power of a single wind turbine in the event of a fault at PCC2 when the adaptive control according to the present disclosure is not added. Figure 15B is a graph showing the power of a single wind turbine in the event of a fault at PCC2 when the adaptive control according to the present disclosure is added. In Figure 15A and Figure 15B , the upper curve is the active power curve of a single wind turbine, and the lower curve is the reactive power curve of a single wind turbine. Comparing Figure 15A and Figure 15B it can be found that, compared with the case where the adaptive control according to the present disclosure is not added, when the adaptive control according to the present disclosure is added, after the fault is cleared, the power recovery speed is significantly improved, and the reactive power impact is alleviated.

[0113] Figure 16A is a graph showing the frequency of the converter in the event of a fault at PCC2 when the adaptive control according to the present disclosure is not added. Figure 16B is a graph showing the frequency of the converter in the event of a fault at PCC2 when the adaptive control according to the present disclosure is added. Comparing Figure 16A and Figure 16B it can be found that, compared with the case where the adaptive control according to the present disclosure is not added, when the adaptive control according to the present disclosure is added, during the fault, in order to ensure that the converter is not damaged due to overcurrent, the frequency is actively reduced to reduce the fault current, and it returns to 20 Hz after the fault ends.

[0114] Figure 17A is a graph showing the voltage and current at PCC2 in the event of a fault at PCC2 when the adaptive control according to the present disclosure is not added. Figure 17B is a graph showing the voltage and current at PCC2 in the event of a fault at PCC2 when the adaptive control according to the present disclosure is added. InFigure 17A and Figure 17B In, the upper curve is the voltage curve at PCC2, and the lower curve is the current curve at PCC2. Comparing Figure 17A and Figure 17B It can be found that, compared with the case where the adaptive control according to the present disclosure is not added, in the case where the adaptive control according to the present disclosure is added, the impact of the fault current on the system is significantly reduced.

[0115] Figure 18A is a graph showing the power at PCC2 in the case of a fault at PCC2 when the adaptive control according to the present disclosure is not added. Figure 18B is a graph showing the power at PCC2 in the case of a fault at PCC2 when the adaptive control according to the present disclosure is added. In Figure 18A and Figure 18B the upper curve is the active power curve at PCC2, and the lower curve is the reactive power curve at PCC2. Comparing Figure 18A and Figure 18B It can be found that, compared with the case where the adaptive control according to the present disclosure is not added, in the case where the adaptive control according to the present disclosure is added, after the fault is cleared, the power recovery speed is significantly increased, and the reactive power impact is alleviated.

[0116] Figure 19A is a graph showing the DC-side power of the DRU in the case of a fault at PCC2 when the adaptive control according to the present disclosure is not added. Figure 19B is a graph showing the DC-side power of the DRU in the case of a fault at PCC2 when the adaptive control according to the present disclosure is added. Comparing Figure 19A and Figure 19B It can be found that, compared with the case where the adaptive control according to the present disclosure is not added, in the case where the adaptive control according to the present disclosure is added, after the fault is cleared, the power recovery speed is significantly increased.

[0117] Figure 20 is a block diagram showing an AC fault ride-through control device for a grid-forming wind turbine according to an exemplary embodiment of the present disclosure.

[0118] In the example, the grid-forming wind turbine is arranged in a DC power transmission system based on a diode rectifier unit. As Figure 20As shown, the AC fault ride-through control device 2000 of the grid-forming wind turbine according to an exemplary embodiment of the present disclosure includes: a voltage error determination unit 2001 that determines a voltage error value based on a measured value and a reference value of the output voltage of the converter of the wind turbine, wherein the reference value of the output voltage is the rated voltage amplitude of the AC side of the diode rectifier unit; a parameter adjustment unit 2002 that adjusts the reference value of the active power and the reference frequency and the frequency measured value of the output voltage of the converter of the wind turbine based on the voltage error value; an active power and frequency control unit that performs active power control on the wind turbine based on the adjusted reference value of the active power, and performs frequency control on the wind turbine based on the adjusted reference frequency and the frequency measured value.

[0119] In an example, the measured value of the output voltage of the converter of the wind turbine is the actual measured value of the d-axis of the output voltage, and the voltage error value is the difference between the rated voltage amplitude of the AC side of the diode rectifier unit and the actual measured value of the d-axis.

[0120] In an example, the parameter adjustment unit 2002 is configured to: in response to the voltage error value being less than a first threshold, set the reference value of the active power to a first power value greater than zero; in response to the voltage error value being greater than the first threshold and less than a second threshold, reduce the reference value of the active power from the first power value to a second power value at a first predetermined slope; in response to the voltage error value being greater than the second threshold, set the reference value of the active power to zero, and reduce the voltage feedforward value at a second predetermined slope to reduce the reference value of the output voltage of the converter of the wind turbine. In an example, the first threshold and the second threshold are determined based on the rated voltage of the filter capacitor of the converter of the wind turbine. In an example, the first predetermined slope and the second predetermined slope are determined based on the first threshold and the second threshold.

[0121] In an example, the parameter adjustment unit 2002 is configured to: in response to the voltage error value being less than a first threshold, set the reference frequency of the output voltage of the converter of the wind turbine to a first reference frequency value; in response to the voltage error value being greater than the first threshold and less than a second threshold, reduce the reference frequency of the output voltage of the converter of the wind turbine from the first reference frequency value to a second reference frequency value at a third predetermined slope, and reduce the frequency feedforward value at a fourth predetermined slope to reduce the frequency measured value of the output voltage of the converter of the wind turbine; in response to the voltage error value being greater than the second threshold, set the reference frequency of the output voltage of the converter of the wind turbine to zero. In an example, the third predetermined slope and the fourth predetermined slope are determined based on the first threshold and the second threshold.

[0122] The above combination Figure 1 、 Figure 3 and Figure 4 The specific operations shown are respectively performed byFigure 20 It is executed by the corresponding unit in the AC fault ride-through control device 2000 of the grid-forming wind turbine shown. Here, the specific operation details will not be elaborated further. By adopting the AC fault ride-through control device of the grid-forming wind turbine according to the exemplary embodiment of the present disclosure, it is possible to determine whether the wind turbine enters the fault ride-through strategy using the local information voltage amplitude without additional fault information, and to reduce the converter fault current.

[0123] Figure 21 It is a block diagram showing a computing system including at least one computing device and at least one storage device storing instructions according to an exemplary embodiment of the present disclosure.

[0124] As Figure 21 As shown, the computing system 2100 provided according to the exemplary embodiment of the present invention includes a computing device 2101 and a storage device 2102. Computer-executable instructions are stored in the storage device 2102. When the computer-executable instructions are executed by the computing device 2101, the AC fault ride-through control method of the grid-forming wind turbine described in any of the foregoing embodiments is executed.

[0125] The computing device 2101 is deployed in a server or a client, or can also be deployed on a node device in a distributed network environment. In addition, the computing device 2101 can be a PC computer, a tablet device, a personal digital assistant, a smart phone, a web application, or other devices capable of executing the above instruction set. Here, the computing device does not have to be a single computing device, but can also be a collection of devices or circuits that can execute the above instructions (or instruction sets) individually or jointly. The computing device can also be a part of an integrated control system or a system manager, or can be configured to be interconnected with a local or remote (e.g., via wireless transmission) portable electronic device. In the computing device, the processor includes a central processing unit (CPU), a graphics processing unit (GPU), a programmable logic device, a dedicated processor system, a microcontroller, or a microprocessor. By way of example and not limitation, the processor also includes an analog processor, a digital processor, a microprocessor, a multi-core processor, a processor array, a network processor, etc.

[0126] According to another aspect of the present disclosure, there is provided a computer-readable storage medium storing instructions, which, when executed by at least one computing device, cause the at least one computing device to execute the AC fault ride-through control method for the grid-forming wind turbine generator set according to any one of the foregoing embodiments. The computer-readable storage medium includes magnetic media such as floppy disks and magnetic tapes, optical media (including CD-ROMs and DVD-ROMs), magneto-optical media such as magneto-optical disks, hardware devices such as ROM and RAM designed to store and execute program commands, and flash memories. The instructions may include language codes executable by a computer using an interpreter and machine language codes generated by a compiler.

[0127] According to one aspect of the present disclosure, there is provided a grid-forming wind turbine generator set, which includes a controller configured to execute the AC fault ride-through control method for the grid-forming wind turbine generator set as described above.

[0128] By adopting the present disclosure, it is possible to determine whether a local wind turbine enters a fault ride-through strategy by using the local information voltage amplitude without additional fault information; and it is possible to perform adaptive control based on the local voltage information to reduce the converter fault current, ensure timely disconnection of the faulty converter, and enable the non-faulty converter to continue operating.

[0129] The processes, methods, or algorithms disclosed herein may be transferred to or implemented by a processing device, a controller, or a computer, which may include any existing programmable electronic control unit or a dedicated electronic control unit. Similarly, the processes, methods, or algorithms may be stored in various forms as data and instructions executable by a controller or a computer, and the various forms include, but are not limited to, information being permanently stored on a non-writable storage medium (such as a ROM device) and information being variably stored on a writable storage medium (such as a floppy disk, a magnetic tape, a CD, a RAM device, and other magnetic and optical media). The processes, methods, or algorithms may also be implemented in software-executable objects. Optionally, the processes, methods, or algorithms may be wholly or partially implemented using appropriate hardware components (such as ASICs, FPGAs, state machines, controllers, or other hardware components or devices), or a combination of hardware components, software components, and firmware components.

[0130] Although the present disclosure includes specific examples, it will be apparent to those of ordinary skill in the art that various changes in form and detail may be made in these examples without departing from the spirit and scope of the claims and their equivalents. The examples described herein are to be considered in a descriptive sense only and not for purposes of limitation. The description of each feature or aspect in an example is to be considered applicable to similar features or aspects in other examples. Suitable results may be obtained if the techniques described are performed in a different order and / or if components in the described systems, architectures, devices, or circuits are combined in a different manner and / or replaced or supplemented by other components or their equivalents. Accordingly, the scope of the present disclosure is not limited by the specific embodiments, but is defined by the claims and their equivalents, and all variations within the scope of the claims and their equivalents are to be construed as being included in the present disclosure.

Claims

1. An AC fault ride-through control method for a grid-forming wind turbine generator set, characterized in that, The wind turbine generator set is arranged in a DC power transmission system based on a diode rectifier unit, and the AC fault ride-through control method includes: Based on the measured value and the reference value of the output voltage of the converter of the wind turbine generator set, determine the voltage error value, where the reference value of the output voltage is the rated voltage amplitude of the AC side of the diode rectifier unit; Based on the voltage error value, adjust the reference value of the active power and the reference frequency and the measured frequency of the output voltage; Based on the adjusted reference value of the active power, perform active power control on the wind turbine generator set, and based on the adjusted reference frequency and the measured frequency value, perform frequency control on the wind turbine generator set.

2. The AC fault ride-through control method for a network-forming wind turbine generator set according to claim 1, wherein, The measured value of the output voltage of the converter of the wind turbine generator set is the actually measured value of the d-axis of the output voltage, and the voltage error value is the difference between the rated voltage amplitude of the AC side and the actually measured value of the d-axis.

3. The AC fault ride-through control method for the network-forming wind turbine generator set according to claim 1, wherein The step of adjusting the reference value of the active power based on the voltage error value includes: In response to the voltage error value being less than the first threshold, set the reference value of the active power to a first power value greater than zero; In response to the voltage error value being greater than the first threshold and less than the second threshold, reduce the reference value of the active power from the first power value to the second power value at a first predetermined slope; In response to the voltage error value being greater than the second threshold, set the reference value of the active power to zero, and reduce the voltage feedforward value at a second predetermined slope to reduce the reference value of the output voltage.

4. The AC fault ride-through control method for the grid-forming wind turbine generator set according to claim 3, wherein, The first threshold and the second threshold are determined based on the rated voltage of the filter capacitor of the converter of the wind turbine generator set.

5. The AC fault ride-through control method for a grid-forming wind turbine generator set according to claim 3, characterized in that, The first predetermined slope and the second predetermined slope are determined based on the first threshold and the second threshold.

6. An AC fault ride-through control device for a grid-forming wind turbine generator, characterized in that, The wind turbine generator set is arranged in a DC power transmission system based on a diode rectifier unit, and the AC fault ride-through control device includes: A voltage error determination unit, which determines a voltage error value based on the measured value and the reference value of the output voltage of the converter of the wind turbine generator set, where the reference value of the output voltage is the rated voltage amplitude of the AC side of the diode rectifier unit; A parameter adjustment unit, which adjusts the reference value of the active power and the reference frequency and the measured frequency of the output voltage based on the voltage error value; An active power and frequency control unit, which performs active power control on the wind turbine generator set based on the adjusted reference value of the active power, and performs frequency control on the wind turbine generator set based on the adjusted reference frequency and the measured frequency value.

7. A network-forming wind turbine generator, characterized in that, The grid-forming wind turbine generator set includes a controller, and the controller is configured to execute the AC fault ride-through control method of the grid-forming wind turbine generator set according to any one of claims 1 to 5.

8. An offshore wind power transmission system, characterized in that, The offshore wind power transmission system includes: Multiple grid-forming wind turbine generator sets, which are connected in parallel with each other; A step-up transformer, the primary side of which is connected to the output terminals of the multiple grid-forming wind turbine generator sets; and A diode rectifier unit, which is connected to the secondary side of the step-up transformer and outputs high-voltage direct current, Among them, each grid-forming wind turbine generator includes a controller, and the controller is configured to execute the AC fault ride-through control method for the grid-forming wind turbine generator according to any one of claims 1 to 5.

9. The offshore wind power transmission system according to claim 8, wherein The output end of the converter of each grid-forming wind turbine generator is connected to the primary side of the fan transformer of the corresponding grid-forming wind turbine generator via a first common connection point.

10. The offshore wind power transmission system according to claim 8, wherein, The secondary side of the fan transformer of each grid-forming wind turbine generator is connected to the primary side of the step-up transformer via a second common connection point.

11. A computing system comprising at least one computing device and at least one storage device storing instructions, characterized in that, When the instruction is run by the at least one computing device, the at least one computing device is caused to execute the AC fault ride-through control method for the grid-forming wind turbine generator according to any one of claims 1 to 5.

12. A computer-readable storage medium storing instructions, characterized in that, When the instruction is run by at least one computing device, the at least one computing device is caused to execute the AC fault ride-through control method for the grid-forming wind turbine generator according to any one of claims 1 to 5.

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