A wind turbine generator through flexible direct grid test device and real-time simulation method

Abstract

The application discloses a wind turbine through flexible direct current grid connection testing device and a real-time simulation method, comprising: a real-time simulation unit, used for simulating the operation characteristics of the flexible direct current transmission system, calculating the grid connection point voltage reference value, and sending the grid connection point voltage reference value to a power amplification unit; the power amplification unit is used for amplifying the required grid connection point voltage to the voltage level matched with the tested wind turbine based on the grid connection point voltage reference value, so that the tested wind turbine carries out grid connection test. The application can construct the operation characteristics of the flexible direct current transmission system at the grid connection point of the tested wind turbine, accurately simulate the operation characteristics of the flexible direct current transmission system, realize the test and detection on the grid connection characteristics of the wind turbine through the flexible direct current transmission through the online collection and analysis of the test process.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of new energy grid connection and control technology, and more particularly, to a wind turbine generator through flexible direct current grid connection testing device and real-time simulation method. BACKGROUND

[0002] With the development and construction of Shachanghuang large-scale wind power base and deep sea wind power, flexible direct current transmission has become one of the important forms of wind power grid connection and transmission. When wind power is transmitted through flexible direct current, there are great differences between the system characteristics and the conventional alternating current transmission, and the operation of wind power through flexible direct current system is jointly affected by wind turbine generator and flexible direct current.

[0003] Therefore, in order to accurately test the grid connection characteristics of wind turbine generator, the operation characteristics of flexible direct current transmission system should be accurately simulated, and a wind turbine generator through flexible direct current grid connection testing device and corresponding real-time simulation method are urgently needed. SUMMARY

[0004] The present application provides a wind turbine generator through flexible direct current grid connection testing device and real-time simulation method to solve the problem of how to test the wind turbine generator through flexible direct current grid connection.

[0005] In order to solve the above problems, according to one aspect of the present application, a wind turbine generator through flexible direct current grid connection testing device is provided, which comprises: a real-time simulation unit and a power amplification unit; wherein,

[0006] The real-time simulation unit is used to simulate the operation characteristics of the flexible direct current transmission system, calculate the grid connection point voltage reference value, and send it to the power amplification unit;

[0007] The power amplification unit is used to amplify the required grid connection point voltage to the voltage level matched with the tested wind turbine generator based on the grid connection point voltage reference value, so as to carry out grid connection test for the tested wind turbine generator.

[0008] Preferably, the real-time simulation unit comprises: a sending end converter station simulation module, a receiving end converter station simulation module, a sending end converter station control module, a receiving end converter station control module and a receiving end power grid simulation module; wherein,

[0009] The sending end converter station simulation module is connected with the sending end converter station control module, and is used to simulate the primary topology of the modular multilevel converter of the sending end in the flexible direct current transmission system in real time;

[0010] The receiving end converter station simulation module is connected with the receiving end converter station control module, and is used to simulate the primary topology of the modular multilevel converter of the receiving end in the flexible direct current transmission system in real time;

[0011] The sending-end converter station control module is configured to collect three-phase instantaneous voltage and current signals from the sending-end converter station simulation module, and send control instructions to the sending-end converter station simulation module, so as to perform real-time simulation on the control system of the sending-end modular multilevel converter.

[0012] The receiving-end converter station control module is configured to collect three-phase instantaneous voltage and current signals and DC voltage signals from the receiving-end converter station simulation module, and send control instructions to the receiving-end converter station simulation module, so as to perform real-time simulation on the control system of the receiving-end modular multilevel converter.

[0013] The receiving-end power grid simulation module is configured to perform real-time simulation on the wind turbine through the flexible DC sending receiving-end AC power grid.

[0014] Preferably, the power amplification unit comprises a rectifier-side converter, an inverter-side converter and a power amplification unit controller, wherein

[0015] The rectifier-side converter is configured to convert grid voltage into DC voltage.

[0016] The inverter-side converter is configured to convert the DC voltage into AC voltage and output the AC voltage to the grid connection point of the wind turbine under test.

[0017] The power amplification unit controller is configured to control the rectifier-side converter to convert grid voltage into DC voltage, and control the inverter-side converter to output the required AC voltage based on the control signal of the sending-end converter station simulation module in the real-time simulation unit.

[0018] Preferably, the power amplification unit controller is further configured to send the three-phase current output by the wind turbine under test to the inverter-side converter to the sending-end converter station simulation module in the real-time simulation unit, so as to complete closed-loop simulation and calculation in the real-time simulation unit.

[0019] Preferably, the rectifier-side converter and the inverter-side converter adopt an H-bridge cascade structure based on IGBT or a three-level full-bridge cascade structure based on IGCT.

[0020] According to another aspect of the present application, a real-time simulation test method based on the wind turbine through flexible DC grid connection test device is provided, and the method comprises the following steps:

[0021] The sending-end converter station simulation module is used to perform real-time simulation on the modular multilevel converter primary topology of the sending end in the flexible DC sending system.

[0022] The receiving-end converter station simulation module is used to perform real-time simulation on the modular multilevel converter primary topology of the receiving end in the flexible DC sending system.

[0023] The sending-end converter station control module collects three-phase instantaneous voltage and current signals from the sending-end converter station simulation module and sends control instructions to the sending-end converter station simulation module to perform real-time simulation on the control system of the sending-end modular multilevel converter.

[0024] The receiving-end converter station control module collects three-phase instantaneous voltage and current signals from the receiving-end converter station simulation module and sends control instructions to the receiving-end converter station simulation module to perform real-time simulation on the control system of the receiving-end modular multilevel converter.

[0025] The receiving-end power grid simulation module performs real-time simulation on the receiving-end AC power grid to which the wind turbine is connected via the flexible DC transmission.

[0026] Preferably, the power amplification unit comprises a rectifier-side converter, an inverter-side converter, and a power amplification unit controller.

[0027] The rectifier-side converter converts the grid voltage into a DC voltage.

[0028] The inverter-side converter converts the DC voltage into an AC voltage and outputs the AC voltage to the grid connection point of the wind turbine under test.

[0029] The power amplification unit controller controls the rectifier-side converter to convert the grid voltage into a DC voltage and controls the inverter-side converter to output the required AC voltage based on the control signal of the sending-end converter station simulation module in the real-time simulation unit.

[0030] Preferably, the method further comprises:

[0031] The power amplification unit controller sends the three-phase current output by the wind turbine under test to the inverter-side converter to the sending-end converter station simulation module in the real-time simulation unit to complete closed-loop simulation and calculation in the real-time simulation unit.

[0032] Preferably, the rectifier-side converter and the inverter-side converter adopt an H-bridge cascade structure based on IGBT or a three-level full-bridge cascade structure based on IGCT.

[0033] The application provides a wind turbine through flexible direct current grid connection testing device and real-time simulation method, comprising: a real-time simulation unit, used for simulating the operation characteristics of the flexible direct current sending-out system, calculating the grid connection point voltage reference value and sending to the power amplification unit; a power amplification unit, used for amplifying the required grid connection point voltage to the voltage level matched with the tested wind turbine based on the grid connection point voltage reference value, so as to make the tested wind turbine carry out grid connection test. The application can simulate the operation characteristics of the flexible direct current sending-out system by constructing the flexible direct current sending-out system operation characteristics at the grid connection point of the tested wind turbine, and realize the test and detection of the grid connection characteristics of the wind turbine through the flexible direct current sending-out by online collection and analysis of the test process. BRIEF DESCRIPTION OF DRAWINGS

[0034] The exemplary embodiments of the present application can be more fully understood by reference to the following drawings:

[0035] Figure 1 It is a structural schematic diagram of the wind turbine through flexible direct current grid connection testing device 100 according to the embodiment of the application;

[0036] Figure 2 It is a real-time simulation and testing principle diagram of the wind turbine through flexible direct current grid connection according to the embodiment of the application;

[0037] Figure 3 It is a connection schematic diagram of the wind turbine through flexible direct current grid connection testing device according to the embodiment of the application;

[0038] Figure 4 It is an interaction schematic diagram between the testing device and the tested wind turbine according to the embodiment of the application;

[0039] Figure 5 It is a flow chart of the wind turbine through flexible direct current grid connection testing method 500 according to the embodiment of the application. DETAILED DESCRIPTION

[0040] The exemplary embodiments of the present application will now be described with reference to the accompanying drawings. The present application can, however, be carried out in many different ways, and is not limited to the embodiments described herein. These embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the application to those skilled in the art. The terminology used in the description of the exemplary embodiments presented herein is not intended to be limiting. Identical elements in the exemplary embodiments shown in the drawings are designated with the same reference numerals.

[0041] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0042] Figure 1 A structural schematic diagram of a wind turbine through flexible direct current grid-connection testing device 100 according to an embodiment of the present application. As shown in the figure, the wind turbine through flexible direct current grid-connection testing device provided by the embodiment of the present application can construct the operation characteristics of the flexible direct current transmission system at the grid-connection point of the tested wind turbine, accurately simulate the operation characteristics of the flexible direct current transmission system, and realize the testing and detection of the grid-connection characteristics of the wind turbine through the flexible direct current transmission by means of online collection and analysis of the testing process. The wind turbine through flexible direct current grid-connection testing device 100 provided by the embodiment of the present application comprises a real-time simulation unit 101 and a power amplification unit 102. Figure 1

[0043] Preferably, the real-time simulation unit 101 is configured to simulate the operation characteristics of the flexible direct current transmission system, calculate the voltage reference value of the grid-connection point, and send the voltage reference value to the power amplification unit.

[0044] Preferably, the real-time simulation unit 101 comprises a sending-end converter station simulation module, a receiving-end converter station simulation module, a sending-end converter station control module, a receiving-end converter station control module, and a receiving-end power grid simulation module; wherein,

[0045] The sending-end converter station simulation module is connected to the sending-end converter station control module and is configured to perform real-time simulation on the primary topology of the modular multilevel converter at the sending end of the flexible direct current transmission system.

[0046] The receiving-end converter station simulation module is connected to the receiving-end converter station control module and is configured to perform real-time simulation on the primary topology of the modular multilevel converter at the receiving end of the flexible direct current transmission system.

[0047] The sending-end converter station control module is configured to collect three-phase instantaneous voltage and current signals from the sending-end converter station simulation module, and send control instructions to the sending-end converter station simulation module to perform real-time simulation on the control system of the modular multilevel converter at the sending end.

[0048] The receiving-end converter station control module is configured to collect three-phase instantaneous voltage and current signals and DC voltage signals from the receiving-end converter station simulation module, and send control instructions to the receiving-end converter station simulation module to perform real-time simulation on the control system of the modular multilevel converter at the receiving end.

[0049] ​The receiving-end power grid simulation module is used to perform real-time simulation of the wind turbine generator transmitting power to the receiving-end AC power grid via flexible DC transmission.

[0050] Preferably, the power amplification unit 102 is used to amplify the required grid connection point voltage to a voltage level that matches the wind turbine under test based on the grid connection point voltage reference value, so that the wind turbine under test can carry out grid connection testing.

[0051] Preferably, the power amplification unit 102 includes: a rectifier-side converter, an inverter-side converter, and a power amplification unit controller; wherein,

[0052] The rectifier-side converter and inverter-side converter are used to convert the grid voltage into DC voltage, and then into AC voltage to output to the grid connection point of the wind turbine under test.

[0053] The power amplifier unit controller is used to control the rectifier-side converter to convert AC voltage to DC voltage, and based on the control signal of the sending-end converter station simulation module in the real-time simulation unit, to control the inverter-side converter to output the required AC voltage.

[0054] Preferably, the power amplification unit controller is further configured to send the three-phase current output from the wind turbine generator to the inverter-side converter to the sending-end converter station simulation module of the real-time simulation unit, so as to complete closed-loop simulation and calculation in the real-time simulation unit.

[0055] Preferably, the rectifier-side converter and the inverter-side converter adopt an H-bridge cascaded structure based on IGBT or a three-level full-bridge cascaded structure based on IGCT.

[0056] Combination Figure 2 As shown, in this invention, for wind turbine generators connected to a flexible DC transmission system, a real-time simulation unit is used to simulate the flexible DC transmission system, and the grid connection point voltage reference calculated by the real-time simulation unit is sent to the power amplification unit. Then, based on the received grid connection point voltage reference, the power amplification unit amplifies the required grid connection point voltage to a voltage level matching the wind turbine generator under test, enabling the wind turbine generator under test to connect and conduct grid connection testing.

[0057] Combination Figure 3 As shown, in this invention, the function of the real-time simulation unit is to simulate the operating characteristics of the flexible DC transmission system and output the AC side voltage signal of the sending-end converter station to the controller in the power amplifier unit. The real-time simulation unit includes: a sending-end converter station simulation module, a receiving-end converter station simulation module, a sending-end converter station control module, a receiving-end converter station control module, and a receiving-end power grid simulation module.

[0058] The sending end converter station simulation module and the receiving end converter station simulation module are used for real-time simulation of the sending end and receiving end modular multilevel converter primary topologies in the flexible DC sending system, and the two simulation modules comprise small-step calculation sub-modules based on FPGA chips, which are used for performing modular multilevel converter topology simulation calculation.

[0059] The sending end converter station control module and the receiving end converter station control module are used for real-time simulation of the control systems of the sending end modular multilevel converter and the receiving end modular multilevel converter, and the two control modules respectively acquire three-phase instantaneous voltage and current signals from the sending end converter station simulation module and the receiving end converter station simulation module, and send control instructions to the corresponding simulation modules. The sending end converter station control module and the receiving end converter station control module comprise CPU-based calculation sub-modules, which are used for performing modular multilevel converter control simulation calculation.

[0060] The receiving end power grid simulation module is used for real-time simulation of the flexible DC sending receiving end AC power grid of the wind turbine, and the module comprises a CPU-based calculation sub-module, which is used for performing receiving end power grid simulation calculation.

[0061] In the real-time simulation unit, the communication between the sending end converter station simulation module, the receiving end converter station simulation module, the sending end converter station control module, the receiving end converter station control module and the receiving end power grid simulation module adopts an optical fiber mode.

[0062] In the application, the power amplification unit is connected between the test wind turbine and the external power grid, and its function is to provide grid-connected voltage for the test wind turbine and transmit the active power output by the test wind turbine to the power grid. The power amplification unit comprises a rectifier side converter, an inverter side converter and a power amplification unit controller.

[0063] The rectifier side converter and the inverter side converter are used for converting the grid voltage into a DC voltage, and then converting the DC voltage into an AC voltage output to the grid-connected point of the test wind turbine, and the AC side voltage is 35kV or 66kV, which can adopt an H-bridge cascade based on IGBT or a three-level full-bridge cascade based on IGCT structure.

[0064] The power amplification unit controller is used for controlling the rectifier side converter to realize the conversion of the AC voltage into the DC voltage, receiving the signal sent by the sending end converter station simulation module in the real-time simulation unit, and controlling the inverter side converter to output the corresponding AC voltage for the grid connection of the test wind turbine.

[0065] In combination with Figure 4 As shown in the figure, in the application, in order to realize the interaction between the test device and the test wind turbine, in each interaction step, the sending end flexible DC converter station AC side three-phase voltage instantaneous value simulated by the sending end converter station simulation module in the real-time simulation unit is sent to the power amplification unit controller, and the power amplification unit controller controls the inverter side converter to output the corresponding AC voltage for the grid connection of the test wind turbine. The sending to the power amplifier unit controller in the power amplifier unit, and the switch control signal is generated by the power amplifier unit controller according to the sending The inverter-side converter in the power amplifier unit is controlled according to The output voltage waveform provides the test wind turbine with grid-connected voltage. Meanwhile, the three-phase current instantaneous values iabc output by the test wind turbine to the inverter-side converter are collected, and the iabc are sent to the power amplifier unit controller to generate the switch control signal abc The sending to the sending converter station simulation module, so as to complete closed-loop simulation and calculation in the real-time simulation unit.

[0066] The starting and running mode of the test device of the application is as follows:

[0067] Step 1: Start the receiving end power grid simulation module in the real-time simulation unit, and start the simulation of the receiving end power grid system;

[0068] Step 2: Start the receiving end converter station simulation module and the receiving end converter station control module, so that the receiving end converter station starts running and is connected to the receiving end power grid in the real-time simulation unit;

[0069] Step 3: Start the sending converter station simulation module and the sending converter station control module, so that the sending converter station starts running and is interconnected with the receiving end converter station in the real-time simulation unit.

[0070] Step 4: In the power amplifier unit, the rectifier-side converter is started and run by the power amplifier unit controller, and the power amplifier unit DC voltage is established by rectification of the external power grid.

[0071] Step 5: In the power amplifier unit, the inverter-side converter is started and run by the power amplifier unit controller, and the AC side output voltage is established according to the three-phase voltage reference value of the AC side of the sending flexible DC converter station sent by the sending converter station simulation module in the real-time simulation unit.

[0072] Step 6: The test wind turbine starts running and is connected to the inverter-side converter in the power supply, so as to realize the overall system running and carry out subsequent tests.

[0073] The device of the application can construct the running characteristics of the flexible DC sending system at the grid-connected point of the test wind turbine, and realize the test and detection of the grid-connected characteristics of the wind turbine through the online collection and analysis of the test process.

[0074] Figure 5 The flowchart of the wind turbine real-time simulation test method 500 according to the embodiment of the application is shown in FIG. 5. As shown in FIG. 5, the method 500 includes the following steps: Figure 5As shown, the simulation test method 500 based on the wind turbine generator through flexible DC grid real-time simulation test device provided by the embodiment of the application is started from step 501. In step 501, the real-time simulation unit simulates the operating characteristics of the flexible DC transmission system, calculates the grid connection point voltage reference value, and sends it to the power amplification unit.

[0075] Preferably, the real-time simulation unit comprises a sending-end converter station simulation module, a receiving-end converter station simulation module, a sending-end converter station control module, a receiving-end converter station control module, and a receiving-end power grid simulation module.

[0076] The sending-end converter station simulation module is used to perform real-time simulation on the modular multilevel converter primary topology of the sending end in the flexible DC transmission system.

[0077] The receiving-end converter station simulation module is used to perform real-time simulation on the modular multilevel converter primary topology of the receiving end in the flexible DC transmission system.

[0078] The sending-end converter station control module is used to collect three-phase instantaneous voltage and current signals from the sending-end converter station simulation module, and send control instructions to the sending-end converter station simulation module to perform real-time simulation on the control system of the sending-end modular multilevel converter.

[0079] The receiving-end converter station control module is used to collect three-phase instantaneous voltage and current signals from the receiving-end converter station simulation module, and send control instructions to the receiving-end converter station simulation module to perform real-time simulation on the control system of the receiving-end modular multilevel converter.

[0080] The receiving-end power grid simulation module is used to perform real-time simulation on the receiving-end AC power grid of the wind turbine generator through the flexible DC transmission system.

[0081] In step 502, the power amplification unit amplifies the required grid connection point voltage to a voltage level matched with the test wind turbine generator based on the grid connection point voltage reference value, so that the test wind turbine generator can carry out grid connection test.

[0082] Preferably, the power amplification unit comprises a rectifier side converter, an inverter side converter, and a power amplification unit controller.

[0083] The rectifier side converter is used to convert the grid voltage into a DC voltage.

[0084] The inverter side converter is used to convert the DC voltage into an AC voltage output to the grid connection point of the test wind turbine generator.

[0085] The rectifier side converter is controlled by the power amplifier unit controller to realize the conversion from grid voltage to DC voltage, and the inverter side converter is controlled based on the control signal of the sending end converter simulation module in the real-time simulation unit to realize the output of required AC voltage.

[0086] Preferably, the rectifier side converter and the inverter side converter adopt IGBT-based H-bridge cascade or IGCT-based three-level full-bridge cascade structure.

[0087] Preferably, the method further comprises:

[0088] The three-phase current output from the test wind turbine to the inverter side converter is sent to the sending end converter simulation module of the real-time simulation unit by the power amplifier unit controller, so as to complete the closed-loop simulation and calculation in the real-time simulation unit.

[0089] The wind turbine through HVDC grid-connected real-time simulation test method 500 of the embodiment of the present application corresponds to the wind turbine through HVDC grid-connected real-time simulation test method 100 of another embodiment of the present application, which will not be described here.

[0090] The present application has been described by reference to a few embodiments. However, one of ordinary skill in the art will readily recognize that other embodiments, which are equally valid, are within the scope of the present application as defined by the appended claims, other than those disclosed above.

[0091] Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a" or "an" means "at least one" unless otherwise clearly indicated by the context of the disclosure. The steps of any methods disclosed herein need not be performed in the exact order disclosed, unless explicitly stated.

[0092] Those skilled in the art will appreciate that embodiments of the present application can be provided as methods, systems, or computer program products. Accordingly, the present application can be embodied in the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present application can take the form of a computer program product on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROMs, optical storage media, etc.) embodying computer readable program code.

[0093] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 one or more flow or blocks Figure 1 one or more flow or blocks

[0094] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instructions which implement the function specified in the flowchart block or blocks. Figure 1 one or more flow or blocks Figure 1 one or more flow or blocks

[0095] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 one or more flow or blocks Figure 1 one or more flow or blocks

[0096] Finally, it should be noted that the above-mentioned embodiments are merely used to illustrate the technical solutions of the present application, but not limit the technical solutions of the present application. Although the present application has been described in detail with reference to the above-mentioned embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or equivalent replaced without departing from the spirit and scope of the present application, and any modification or equivalent replacement should be covered in the protection scope of the claims of the present application.

Claims

1. A wind turbine generator unit flexible direct grid connection testing device, characterized in that, The device comprises a real-time simulation unit and a power amplification unit; wherein The real-time simulation unit is configured to simulate the operating characteristics of the flexible DC sending-out system, to calculate a grid-connected point voltage reference value, and to send the grid-connected point voltage reference value to the power amplification unit; The power amplification unit is configured to amplify the required grid-connected point voltage to a voltage level matched with the tested wind turbine for the tested wind turbine to carry out grid-connected testing based on the grid-connected point voltage reference value; The real-time simulation unit comprises a sending-end converter station simulation module, a receiving-end converter station simulation module, a sending-end converter station control module, a receiving-end converter station control module, and a receiving-end power grid simulation module; wherein The sending-end converter station simulation module is connected to the sending-end converter station control module, and is configured to perform real-time simulation on the primary topology of the modular multilevel converter at the sending end of the flexible DC sending-out system; The receiving-end converter station simulation module is connected to the receiving-end converter station control module, and is configured to perform real-time simulation on the primary topology of the modular multilevel converter at the receiving end of the flexible DC sending-out system; The sending-end converter station control module is configured to collect three-phase instantaneous voltage and current signals from the sending-end converter station simulation module, and to send control instructions to the sending-end converter station simulation module to perform real-time simulation on the control system of the modular multilevel converter at the sending end; The receiving-end converter station control module is configured to collect three-phase instantaneous voltage and current signals and DC voltage signals from the receiving-end converter station simulation module, and to send control instructions to the receiving-end converter station simulation module to perform real-time simulation on the control system of the modular multilevel converter at the receiving end; The receiving-end power grid simulation module is configured to perform real-time simulation on the receiving-end AC power grid of the wind turbine via the flexible DC sending-out system; The power amplification unit comprises a rectifier-side converter, an inverter-side converter, and a power amplification unit controller; wherein The rectifier-side converter is configured to convert grid voltage into DC voltage; The inverter-side converter is configured to convert the DC voltage into AC voltage and output the AC voltage to the grid-connected point of the tested wind turbine; The power amplification unit controller is configured to control the rectifier-side converter to convert grid voltage into DC voltage, and to control the inverter-side converter to output the required AC voltage based on the control signal of the sending-end converter station simulation module in the real-time simulation unit; The rectifier-side converter and the inverter-side converter adopt an H-bridge cascade structure based on IGBT or a three-level full-bridge cascade structure based on IGCT.

2. The apparatus of claim 1, wherein, The power amplification unit controller is further configured to: send the three-phase current output by the tested wind turbine to the inverter-side converter to the sending-end converter station simulation module of the real-time simulation unit to complete closed-loop simulation and calculation in the real-time simulation unit.

3. A real-time simulation test method based on the flexible direct grid test device of the wind turbine generator set according to any one of claims 1-2, characterized in that, The method comprises: The real-time simulation unit simulates the operating characteristics of the flexible DC sending-out system, calculates a grid-connected point voltage reference value, and sends the grid-connected point voltage reference value to the power amplification unit; The power amplification unit amplifies the required grid-connected point voltage to a voltage level matched with the tested wind turbine for the tested wind turbine to carry out grid-connected testing based on the grid-connected point voltage reference value; The real-time simulation unit comprises a sending-end converter station simulation module, a receiving-end converter station simulation module, a sending-end converter station control module, a receiving-end converter station control module and a receiving-end power grid simulation module. The sending-end converter station simulation module is configured to perform real-time simulation on a modular multilevel converter primary topology of a sending end of the flexible DC transmission system. The receiving-end converter station simulation module is configured to perform real-time simulation on a modular multilevel converter primary topology of a receiving end of the flexible DC transmission system. The sending-end converter station control module is configured to collect three-phase instantaneous voltage and current signals from the sending-end converter station simulation module, and send control instructions to the sending-end converter station simulation module, so as to perform real-time simulation on a control system of the sending-end modular multilevel converter. The receiving-end converter station control module is configured to collect three-phase instantaneous voltage and current signals from the receiving-end converter station simulation module, and send control instructions to the receiving-end converter station simulation module, so as to perform real-time simulation on a control system of the receiving-end modular multilevel converter. The receiving-end power grid simulation module is configured to perform real-time simulation on a receiving-end AC power grid of the wind turbine through the flexible DC transmission system. The power amplification unit comprises a rectifier-side converter, an inverter-side converter and a power amplification unit controller. The rectifier-side converter is configured to convert a grid voltage into a DC voltage. The inverter-side converter is configured to convert the DC voltage into an AC voltage and output the AC voltage to a grid connection point of the test wind turbine. The power amplification unit controller is configured to control the rectifier-side converter to convert the grid voltage into the DC voltage, and control the inverter-side converter to output a required AC voltage based on a control signal of the sending-end converter station simulation module in the real-time simulation unit. The rectifier-side converter and the inverter-side converter adopt an H-bridge cascade structure based on IGBT or a three-level full-bridge cascade structure based on IGCT.

4. The method of claim 3, wherein, The method further comprises: The power amplification unit controller sends three-phase currents output by the test wind turbine to the inverter-side converter to the sending-end converter station simulation module in the real-time simulation unit, so as to complete closed-loop simulation and calculation in the real-time simulation unit.

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