A method and device for LC virtual damping control of a double-fed converter

Abstract

The application discloses a double-fed converter LC virtual damping control method and device, the double-fed converter comprises a machine-side inverter, a double-fed generator and a network-side LC filter which are connected in sequence, the method comprises the following steps: obtaining a rotor instruction current according to a stator instruction current and a stator output current; obtaining a rotor output voltage according to a rotor output current and the rotor instruction current; and performing pulse modulation on the machine-side inverter according to the rotor output voltage, so as to control and adjust the output voltage of the machine-side inverter in the double-fed converter, indirectly control and adjust the output voltage of the generator stator, and realize virtual damping control of the network-side LC filter. The application has the advantages of simple realization method, low cost, high efficiency, and the ability to realize active damping of the network-side LC filter when the network-side output voltage is insufficient.

Description

Technical Field

[0001] This invention relates to the field of doubly-fed converter control technology, and in particular to a doubly-fed converter LC virtual damping control method and device. Background Technology

[0002] Doubly fed induction generator (DFIG) converters (DFIG wind turbine converters) typically require grid-side LC sine wave filters to meet grid-connected power quality requirements. However, LC filters all have resonant points, meaning that signal amplitudes near these resonant frequencies are amplified infinitely. Without effective suppression measures, this can cause system divergence. Therefore, it is necessary to suppress signals near the resonant frequency. The topology of a DFIG wind turbine converter is as follows: Figure 1 As shown, DFIG (Doubly fed Induction Generator) is a doubly fed asynchronous wind turbine.

[0003] For signal suppression near the resonant frequency of the LC filter in a doubly-fed converter, passive damping or active damping methods are commonly used, respectively:

[0004] 1. Using a passive LC damping circuit: Adding a physical resistor to the LC circuit achieves damping; this is equivalent to using hardware to suppress LC damping. Figure 2 As shown. This type of hardware-based LC damping suppression method, while simple and effective, suffers from drawbacks such as high resistive losses, low system efficiency, and high cost.

[0005] 2. Virtual Active LC Damping Control: Virtual active damping is achieved by measuring the resonant frequency and corresponding amplitude and phase voltage at the grid-side inverter output. For example, by collecting the three-phase voltage of the grid, the three-phase output current of the grid-side inverter, and the three-phase current of the grid-side LC filter, the output voltage of the grid-side inverter is obtained by combining the command current and the detection current output by the grid-side inverter. On the other hand, by detecting the current of the grid-side LC filter, the voltage across the virtual resistor is obtained through a virtual capacitor connected in parallel with a resistor. This voltage is then fed forward to the inverter output voltage, achieving virtual damping control of the grid-side LC.

[0006] Compared to passive LC damping circuits, the virtual active LC damping control method described above is simpler to implement, lower in cost, and more efficient. However, this solution can only be used when the grid-side inverter output voltage and switching frequency are suitable. That is, it must be applicable only when the grid-side inverter output voltage and switching frequency meet certain requirements. However, in reality, the grid-side output voltage may be insufficient (modulation ratio saturation). In this case, the virtual active LC damping control method described above will have poor suppression effect or fail. In other words, the virtual active LC damping control method described above is not suitable for situations where the grid-side output voltage is insufficient.

[0007] In summary, existing technologies for suppressing signals near the resonant frequency of LC filters in doubly-fed converters using passive LC damping circuits suffer from high resistance losses, low system efficiency, and high cost. On the other hand, virtual active LC damping control is unsuitable for situations where the grid-side output voltage is insufficient. Therefore, there is an urgent need to provide a virtual LC damping control method for doubly-fed converters that can balance control efficiency and cost while also addressing the virtual damping control problem under insufficient grid-side output voltage conditions. Summary of the Invention

[0008] The technical problem to be solved by this invention is: in view of the technical problems existing in the prior art, this invention provides a doubly fed converter LC virtual damping control method and device that is simple to implement, low in cost and high in efficiency, and can still achieve active damping of the grid-side LC filter when the grid-side output voltage is insufficient.

[0009] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows:

[0010] A virtual damping control method for a doubly-fed inverter (DFIG) comprising a generator-side inverter, a doubly-fed generator, and a grid-side LC filter connected in sequence, characterized in that it includes:

[0011] The rotor command current is obtained from the stator command current and stator output current in the doubly fed generator;

[0012] The rotor output voltage is obtained by comparing the rotor output current in the doubly-fed generator with the rotor command current.

[0013] The output voltage of the machine-side inverter is controlled and adjusted according to the rotor output voltage to indirectly control and adjust the stator output voltage in the doubly-fed generator, thereby realizing the virtual damping control of the grid-side LC filter.

[0014] Furthermore, the rotor command current is obtained by inputting the deviation between the stator command current and the stator output current into the stator current loop PI regulation subunit for PI control.

[0015] Furthermore, by inputting the deviation between the rotor command current and the rotor output current into the rotor current loop PI regulation subunit for PI control, the rotor output voltage is obtained.

[0016] Furthermore, the output voltage of the machine-side inverter is controlled and adjusted by performing PWM pulse modulation on the machine-side inverter according to the rotor output voltage.

[0017] Furthermore, by passing the output voltage of the machine-side inverter through the rotor equivalent leakage reactance to obtain the rotor output current, and inputting the rotor output current into the high-frequency amplitude-frequency characteristic model of the doubly-fed generator, the stator output voltage is obtained.

[0018] Furthermore, the high-frequency amplitude-frequency characteristic of the doubly-fed generator high-frequency amplitude-frequency characteristic model is determined by detecting the amplitude and phase changes of the doubly-fed converter at different LC resonant frequencies.

[0019] Furthermore, the test steps for the high-frequency amplitude-frequency characteristic of the doubly-fed generator high-frequency amplitude-frequency characteristic model include:

[0020] The doubly fed converter system is brought into generator synchronous grid connection state. After successful synchronization, the LC resonant frequency and resonant voltage are inserted; the rotor resonant current and stator resonant voltage are detected at the current LC resonant frequency.

[0021] The amplitude and phase changes of the current high-frequency amplitude-frequency characteristic model of the doubly-fed generator at the LC resonant frequency are calculated. Based on the detection results, the virtual damping parameters are locked, and the high-frequency amplitude-frequency characteristic of the final high-frequency amplitude-frequency characteristic model of the doubly-fed generator is determined.

[0022] Furthermore, the process of bringing the doubly fed converter system into the generator synchronous grid-connected state, after successful synchronization, includes locking the grid-connected correction angle before inserting the LC resonant frequency and resonant voltage.

[0023] A virtual damping control device for a doubly-fed inverter (DFIG) includes a generator-side inverter, a doubly-fed generator, and a grid-side LC filter connected in sequence. The control device includes:

[0024] The rotor command current generation unit is used to obtain the rotor command current based on the stator command current and the stator output current in the doubly fed generator.

[0025] The rotor output voltage generation unit is used to obtain the rotor output voltage based on the rotor output current in the doubly-fed generator and the rotor command current.

[0026] The control and regulation unit is used to control and regulate the output voltage of the machine-side inverter according to the rotor output voltage, so as to indirectly control and regulate the stator output voltage in the doubly-fed generator and realize the virtual damping control of the grid-side LC filter.

[0027] Furthermore, the rotor command current generation unit includes a first deviation calculation subunit and a stator current loop PI adjustment subunit connected in sequence. The first deviation calculation subunit calculates the deviation between the stator command current and the stator output current, and inputs it to the stator current loop PI adjustment subunit for PI control. The stator current loop PI adjustment subunit outputs the rotor command current.

[0028] Furthermore, the rotor output voltage generation unit includes a second deviation calculation subunit and a rotor current loop PI regulation subunit. The second deviation calculation subunit calculates the deviation between the rotor command current and the rotor output current, and inputs it into the rotor current loop PI regulation subunit for PI control. The rotor current loop PI regulation subunit outputs the rotor output voltage.

[0029] Furthermore, the control and regulation unit is a PWM pulse modulator, which controls and regulates the output voltage of the machine-side inverter by performing PWM pulse modulation on the machine-side inverter according to the rotor output voltage.

[0030] Furthermore, it also includes a stator output voltage determination unit, which is used to obtain the rotor output current by passing the output voltage of the machine-side inverter through the rotor equivalent leakage reactance, and input the rotor output current into the high-frequency amplitude-frequency characteristic model of the doubly-fed generator to obtain the stator output voltage.

[0031] Furthermore, the doubly-fed converter is equipped with a program module for testing the high-frequency amplitude-frequency characteristics of the doubly-fed generator's high-frequency amplitude-frequency characteristic model.

[0032] Compared with the prior art, the advantages of the present invention are as follows: The present invention utilizes the characteristics that both ends of the doubly fed wind power converter and the motor system feed current / voltage to the grid and the generator-side output voltage margin is large (low modulation index). By adjusting the output voltage of the generator-side inverter, the output voltage of the generator stator is indirectly controlled to suppress the resonant current on the grid-side LC filter capacitor, thereby realizing the virtual damping of the grid-side LC filter. It is not only simple and low-cost to implement, but also does not require the addition of other hardware structures, balancing implementation efficiency and cost. At the same time, it can still achieve active damping of the grid-side LC filter when the grid-side output voltage is insufficient. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure and principle of a doubly fed converter.

[0034] Figure 2 This is a schematic diagram of the structure and principle of a traditional passive LC damping circuit.

[0035] Figure 3 This is a schematic diagram illustrating the implementation process of the doubly fed converter LC virtual damping control method in this embodiment.

[0036] Figure 4 This is a schematic diagram of the electrical principle of grid-side LC virtual damping control using a machine-side inverter in this embodiment.

[0037] Figure 5This is a schematic diagram of the high-frequency amplitude-frequency characteristic test process of the equivalent transfer function of the doubly-fed generator in this embodiment.

[0038] Figure 6 This is a schematic diagram of the structure of the doubly fed converter LC virtual damping control device in this embodiment.

[0039] Figure 7 This is a schematic diagram of the structure of the LC virtual damping control device for a doubly fed converter in a specific application embodiment. Detailed Implementation

[0040] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but this does not limit the scope of protection of the present invention.

[0041] like Figure 3 As shown, in the doubly-fed converter LC virtual damping control method of this embodiment, the doubly-fed converter includes a machine-side inverter, a doubly-fed generator, and a grid-side LC filter connected in sequence. The method includes:

[0042] S01. Obtain the rotor command current based on the stator command current and stator output current in the doubly-fed generator;

[0043] S02. Obtain the rotor output voltage based on the rotor output current and rotor command current in the doubly-fed generator;

[0044] S03. The output voltage of the generator-side inverter is controlled and adjusted according to the rotor output voltage to indirectly control and adjust the stator output voltage in the doubly-fed generator, thereby realizing the virtual damping control of the grid-side LC filter.

[0045] Doubly fed converters, such as Figure 4 As shown, it includes a machine-side inverter, a doubly-fed generator, and a grid-side LC filter connected in sequence. Figure 4 This can be viewed as follows: besides the grid-side inverter output filter reactor and grid-side filter capacitor forming an LC circuit, the leakage reactance of the doubly-fed generator can also be equivalent to a reactor. Therefore, the doubly-fed generator and grid-side filter capacitor also form an LC circuit. Thus, similar to the principle of virtual damping of the grid-side LC circuit achieved by controlling the grid-side inverter output voltage, the generator stator output voltage can also be indirectly controlled by adjusting the generator-side inverter output voltage to suppress the resonant current on the grid-side LC filter capacitor, thereby achieving virtual damping control of the grid-side LC filter.

[0046] Meanwhile, considering that the grid-side output voltage of the doubly-fed converter is typically 690V, and taking into account the DC voltage of 1050V and the voltage drop of the grid-side reactor, the modulation of the grid-side inverter is close to full modulation. However, due to operating conditions such as overspeed of the doubly-fed motor, the output modulation of the generator-side inverter is typically around 0.5 to 0.7. Therefore, there is sufficient voltage margin to achieve the output of the LC virtual damping control voltage. That is, it is feasible to achieve virtual damping of the grid-side LC filter by adjusting the output voltage of the generator-side inverter. This embodiment utilizes the characteristics that both the doubly-fed wind power converter and the motor system feed current (voltage) to the grid and the generator-side output voltage margin is large (low modulation). By adjusting the output voltage of the generator-side inverter, the output voltage of the generator stator can be indirectly controlled, thereby suppressing the resonant current on the capacitor of the grid-side LC filter and achieving virtual damping of the grid-side LC filter. This method is not only simple and low-cost, requiring no additional hardware structure, but also balances efficiency and cost. Furthermore, it can still achieve active damping of the grid-side LC filter when the grid-side output voltage is insufficient.

[0047] In this embodiment, step S01 specifically involves inputting the deviation between the stator command current and the stator output current into the stator current loop PI control subunit to obtain the rotor command current. That is, by receiving the stator command current, acquiring the stator output current, calculating the deviation, and inputting it into the stator current loop PI control subunit, the stator current loop PI control subunit outputs the rotor command current.

[0048] In this embodiment, step S02 specifically involves inputting the deviation between the rotor command current and the rotor output current into the rotor current loop PI control subunit to obtain the rotor output voltage. That is, by acquiring the rotor output current, calculating the deviation between the rotor output current and the rotor command current output in the previous step, and outputting this deviation to the rotor current loop PI control subunit, which then outputs the rotor output voltage.

[0049] The aforementioned stator current loop PI regulation subunit and rotor current loop PI regulation subunit can be implemented using PI controllers. By configuration, stator current loop PI control and rotor current loop PI control can be achieved respectively. The specific circuit structure can be selected according to actual needs.

[0050] In this embodiment, step S03 specifically involves modulating the generator-side inverter with PWM pulses based on the rotor output voltage to control and regulate the output voltage of the generator-side inverter. That is, based on the rotor output voltage obtained in the previous step, the output voltage of the generator-side inverter is controlled and regulated by modulating it with PWM pulses. By regulating the output voltage of the generator-side inverter, the output voltage of the generator stator can be indirectly controlled and regulated, thereby suppressing the resonant current on the grid-side LC filter capacitor.

[0051] In this embodiment, the rotor output current is obtained by passing the output voltage of the generator-side inverter through the rotor equivalent leakage reactance. The rotor output current is then input into the high-frequency amplitude-frequency characteristic model of the doubly-fed generator to obtain the stator output voltage. Specifically, the high-frequency amplitude-frequency characteristic model of the doubly-fed generator is the equivalent transfer function from the rotor current to the stator voltage. After obtaining the rotor output current in the previous step, the stator output voltage can be obtained based on this equivalent transfer function.

[0052] In this embodiment, the high-frequency amplitude-frequency characteristic of the doubly-fed generator (DFIG) high-frequency amplitude-frequency characteristic model is determined by detecting the amplitude and phase changes of the DFIG converter at different LC resonant frequencies. The high-frequency amplitude-frequency characteristic reflects the amplitude and phase change characteristics of the DFIG converter at different LC resonant frequencies. Therefore, by detecting the amplitude and phase changes of the DFIG converter at different LC resonant frequencies, the high-frequency amplitude-frequency characteristic of the DFIG generator high-frequency amplitude-frequency characteristic model can be obtained. Combining this characteristic, the stator output voltage can be obtained, thereby achieving stator output voltage control and regulation to suppress the resonant current on the grid-side LC filter capacitor.

[0053] like Figure 5 As shown, the specific test steps for the high-frequency amplitude-frequency characteristic model of the doubly-fed generator in this embodiment include:

[0054] S301. Put the doubly fed converter system into generator synchronous grid connection state. After successful synchronization, insert the LC resonant frequency and resonant voltage.

[0055] S302. Detect the rotor resonant current and stator resonant voltage at the current LC resonant frequency;

[0056] S303. Calculate the amplitude and phase changes of the high-frequency amplitude-frequency characteristic model of the doubly-fed generator at the LC resonant frequency, and lock the virtual damping parameters based on the detection results, thereby determining the high-frequency amplitude-frequency characteristic of the final doubly-fed generator high-frequency amplitude-frequency characteristic model.

[0057] Through the above steps, this embodiment can test the high-frequency amplitude-frequency characteristic of the high-frequency amplitude-frequency characteristic model of the doubly-fed generator. Using this characteristic, the stator output voltage can be obtained after obtaining the rotor current, thereby realizing the output voltage control and regulation of the generator stator.

[0058] In this embodiment, the doubly fed converter system is brought into the generator synchronous grid-connected state. After successful synchronization, before inserting the LC resonant frequency and resonant voltage, the grid-connected correction angle is locked.

[0059] The above test steps can be implemented using a program module that can perform the test steps. The program module can be pre-embedded in the doubly fed converter. By running the program module, the high-frequency amplitude-frequency characteristic of the high-frequency amplitude-frequency characteristic model of the doubly fed generator can be easily tested.

[0060] like Figure 6 As shown in this embodiment, the doubly-fed converter LC virtual damping control device includes a machine-side inverter, a doubly-fed generator, and a grid-side LC filter connected in sequence. The control device includes:

[0061] The rotor command current generation unit is used to obtain the rotor command current based on the stator command current and the stator output current in the doubly fed generator.

[0062] The rotor output voltage generation unit is used to obtain the rotor output voltage based on the rotor output current and rotor command current in the doubly-fed generator.

[0063] The control and regulation unit is used to control and regulate the output voltage of the inverter on the machine side according to the rotor output voltage, so as to indirectly control and regulate the stator output voltage in the doubly-fed generator and realize the virtual damping control of the grid-side LC filter.

[0064] In this embodiment, the rotor command current generation unit includes a first deviation calculation subunit and a stator current loop PI regulation subunit connected in sequence. The first deviation calculation subunit calculates the deviation between the stator command current and the stator output current, and inputs it to the stator current loop PI regulation subunit for PI control. The stator current loop PI regulation subunit then outputs the rotor command current. The aforementioned first deviation calculation subunit can be implemented using an adder or a multiplier, and the stator current loop PI regulation subunit can be implemented using a PI regulator.

[0065] In this embodiment, the rotor output voltage generation unit includes a second deviation calculation subunit and a rotor current loop PI regulation subunit. The second deviation calculation subunit calculates the deviation between the rotor command current and the rotor output current, and inputs it to the rotor current loop PI regulation subunit for PI control. The rotor current loop PI regulation subunit outputs the rotor output voltage. The aforementioned second deviation calculation subunit can be implemented using an adder or a multiplier, and the rotor current loop PI regulation subunit can be implemented using a PI regulator.

[0066] In this embodiment, the control and regulation unit is a PWM pulse modulator. The PWM pulse modulator controls and regulates the output voltage of the machine-side inverter by performing PWM pulse modulation on the machine-side inverter according to the rotor output voltage.

[0067] In this embodiment, a stator output voltage determination unit is also included, which is used to obtain the rotor output current by passing the output voltage of the machine-side inverter through the rotor equivalent leakage reactance, and input the rotor output current into the high-frequency amplitude-frequency characteristic model of the doubly-fed generator to obtain the stator output voltage.

[0068] In this embodiment, the doubly-fed converter is equipped with a program module for testing the high-frequency amplitude-frequency characteristic of the high-frequency amplitude-frequency characteristic model of the doubly-fed generator. By starting the program module, the high-frequency amplitude-frequency characteristic of the high-frequency amplitude-frequency characteristic model of the doubly-fed generator can be tested and obtained, so as to determine the stator output voltage.

[0069] The doubly fed converter LC virtual damping control device in this embodiment corresponds one-to-one with the doubly fed converter LC virtual damping control method described above, and will not be described in detail here.

[0070] In a specific application embodiment, the doubly-fed converter LC virtual damping control device of this embodiment is as follows: Figure 7 As shown, it includes the stator current loop PI regulator G. PI_s (s), Rotor current loop PI regulator G PI_r (s), Machine-side inverter PWM pulse modulator K PWM And the high-frequency amplitude-frequency characteristic model G of the doubly fed motor M (s), where G PI_s (s), G PI_r (s) represents the transfer function of the stator current loop and rotor current loop PI regulator, K PWM G is the amplification factor of the machine-side inverter. M (s) is the equivalent transfer function from rotor voltage to stator current of a doubly-fed generator, V g (s), V C (s), V s (s), V r (s), V inv (s) represents the grid voltage, capacitor voltage, stator and rotor voltage, and the inverter output voltage on the machine side. s sL r , sL2 represents the generator stator leakage reactance, rotor leakage reactance, filter capacitor capacitive reactance, and grid equivalent main reactance, respectively. Each signal includes: For stator and rotor command currents, i s (s), i r (s), i C i(s) and i2(s) are the stator, rotor, capacitor, and grid-connected actual currents.

[0071] When the above-mentioned doubly-fed converter LC virtual damping control device is used, the stator command current will be... With stator output current i s The deviation of (s) is input to the stator current loop PI regulator G. PI_s (s) Perform PI control to obtain the rotor command current. Rotor command current With rotor output current i r The deviation of (s) is output to the rotor current loop PI regulator G.PI_r (s) Perform PI control to obtain the rotor output voltage V r (s), and then K is modulated by the PWM pulse of the inverter. PWM The output voltage V of the inverter on the machine side is obtained. inv (s); Output voltage V of the machine-side inverter inv (s) After equivalence of rotor leakage reactance, the rotor output current i is obtained. r (s), rotor output current i r (s) The high-frequency amplitude-frequency characteristic model of the doubly-fed induction generator is used to obtain the stator output voltage V through equivalent voltage-current transfer. s (s); Stator output voltage V s (s) and grid voltage V g The deviation input stator leakage reactance of (s) is equivalent to the stator output current i. s (s), and after passing through the filter capacitor reactance and the grid main reactance equivalent, the final actual grid-connected current i2(s) is obtained and input to the grid. The above, except for G M All models other than (s) can be implemented using existing models.

[0072] The above high-frequency amplitude-frequency characteristic model G of the doubly fed motor M (s) can be equivalent to a first-order inertial element. The high-frequency (LC resonant frequency) amplitude-frequency characteristic of the equivalent transfer function from rotor voltage to stator current of this model is obtained by loading a test program module inside the doubly fed converter and executing the test program module.

[0073] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Therefore, any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention should fall within the protection scope of the present invention.

Claims

1. A virtual damping control method for a doubly-fed inverter (DFIG), wherein the DFIG comprises a machine-side inverter, a doubly-fed generator, and a grid-side LC filter connected in sequence, characterized in that... include: The rotor command current is obtained from the stator command current and stator output current in the doubly fed generator; The rotor output voltage is obtained by comparing the rotor output current in the doubly-fed generator with the rotor command current. The output voltage of the machine-side inverter is controlled and adjusted according to the rotor output voltage, so as to indirectly control and adjust the stator output voltage in the doubly-fed generator, thereby realizing the virtual damping control of the grid-side LC filter; The rotor output current is obtained by passing the output voltage of the machine-side inverter through the rotor equivalent leakage reactance. The rotor output current is then input into the high-frequency amplitude-frequency characteristic model of the doubly-fed generator to obtain the stator output voltage. The high-frequency amplitude-frequency characteristic of the doubly-fed generator high-frequency amplitude-frequency characteristic model is determined by detecting the amplitude and phase changes of the doubly-fed converter at different LC resonant frequencies. The test steps for the high-frequency amplitude-frequency characteristic of the doubly-fed generator high-frequency amplitude-frequency characteristic model include: Enter the generator synchronous grid-connected state of the doubly fed converter system. After successful synchronization, insert the LC resonant frequency and resonant voltage. Detect the rotor resonant current and stator resonant voltage at the current LC resonant frequency; Calculate the amplitude and phase changes of the current high-frequency amplitude-frequency characteristic model of the doubly-fed generator at the LC resonant frequency, lock the virtual damping parameters based on the detection results, and determine the high-frequency amplitude-frequency characteristic of the final high-frequency amplitude-frequency characteristic model of the doubly-fed generator. The process of bringing the doubly fed converter system into generator synchronous grid-connected state, after successful synchronization, before inserting the LC resonant frequency and resonant voltage, also includes locking the grid-connected correction angle.

2. The doubly-fed converter LC virtual damping control method according to claim 1, characterized in that, The rotor command current is obtained by inputting the deviation between the stator command current and the stator output current into the stator current loop PI regulation subunit for PI control.

3. The doubly-fed converter LC virtual damping control method according to claim 1, characterized in that, The rotor output voltage is obtained by inputting the deviation between the rotor command current and the rotor output current into the rotor current loop PI regulation subunit for PI control.

4. The doubly-fed converter LC virtual damping control method according to claim 1, characterized in that, The output voltage of the machine-side inverter is controlled and adjusted by performing PWM pulse modulation on the machine-side inverter according to the rotor output voltage.

5. A doubly-fed converter LC virtual damping control device for implementing the method of any one of claims 1 to 4, wherein the doubly-fed converter comprises a machine-side inverter, a doubly-fed generator, and a grid-side LC filter connected in sequence, characterized in that, The control device includes: The rotor command current generation unit is used to obtain the rotor command current based on the stator command current and the stator output current in the doubly fed generator. The rotor output voltage generation unit is used to obtain the rotor output voltage based on the rotor output current in the doubly-fed generator and the rotor command current. The control and regulation unit is used to control and regulate the output voltage of the machine-side inverter according to the rotor output voltage, so as to indirectly control and regulate the stator output voltage in the doubly-fed generator and realize the virtual damping control of the grid-side LC filter.

6. The doubly-fed converter LC virtual damping control device according to claim 5, characterized in that, The rotor command current generation unit includes a first deviation calculation subunit and a stator current loop PI adjustment subunit connected in sequence. The first deviation calculation subunit calculates the deviation between the stator command current and the stator output current, and inputs it to the stator current loop PI adjustment subunit for PI control. The stator current loop PI adjustment subunit outputs the rotor command current.

7. The doubly-fed converter LC virtual damping control device according to claim 5, characterized in that, The rotor output voltage generation unit includes a second deviation calculation subunit and a rotor current loop PI regulation subunit. The second deviation calculation subunit calculates the deviation between the rotor command current and the rotor output current, and inputs it into the rotor current loop PI regulation subunit for PI control. The rotor current loop PI regulation subunit outputs the rotor output voltage.

8. The doubly-fed converter LC virtual damping control device according to claim 5, characterized in that, The control and regulation unit is a PWM pulse modulator. The PWM pulse modulator controls and regulates the output voltage of the machine-side inverter by performing PWM pulse modulation on the machine-side inverter according to the rotor output voltage.

9. The doubly-fed converter LC virtual damping control device according to any one of claims 5 to 8, characterized in that, It also includes a stator output voltage determination unit, which is used to obtain the rotor output current by passing the output voltage of the machine-side inverter through the rotor equivalent leakage reactance, and input the rotor output current into the high-frequency amplitude-frequency characteristic model of the doubly-fed generator to obtain the stator output voltage.

10. The doubly-fed converter LC virtual damping control device according to claim 9, characterized in that, The doubly-fed converter is equipped with a program module for testing the high-frequency amplitude-frequency characteristics of the doubly-fed generator high-frequency amplitude-frequency characteristic model.

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