SVG virtual impedance adaptive switching control method and system

Abstract

The application discloses an SVG virtual impedance adaptive switching control method and system, mainly including a virtual series impedance control link, a virtual parallel impedance control link and an SVG double closed loop control link; the oscillation frequency of a new energy station is monitored through VMD and HT transformation, the optimal virtual impedance control loop is put into operation, and the output of the virtual impedance control link is compensated to the original double closed loop control structure of the SVG as a compensation amount, so that the SVG obtains more superior oscillation suppression effect in a wide frequency range, and the limitation that a single virtual impedance control method is difficult to adapt to multi-frequency band oscillation suppression demand is overcome. The application can be widely applied to wind power, photovoltaic and other new energy grid-connected systems containing SVG, and provides an effective solution for wide frequency oscillation suppression and safe and stable operation of the new energy grid-connected systems.

Description

Technical Field

[0001] This invention relates to the field of stability analysis and control technology for new energy power generation systems, and in particular to an SVG virtual impedance adaptive switching control method and system. Background Technology

[0002] Renewable energy power plants typically require reactive power compensation devices accounting for 20%-30% of their installed capacity. Static Var Generators (SVGs), due to their excellent dynamic performance, are widely used in wind power, photovoltaic, and other renewable energy power plants to achieve rapid and precise voltage regulation. However, in highly power-electronic renewable energy power plants composed of SVGs and renewable energy generation units, the dynamic interaction between multiple equipment control systems and between these systems and the weak grid can easily lead to broadband oscillations ranging from subsynchronous to mid-to-high frequency bands. These oscillations not only affect power quality and equipment safety but may also escalate into system-level stability risks, severely restricting the high-proportion consumption of renewable energy and the safe operation of the power grid.

[0003] Optimizing the SVG control structure can give it a certain broadband oscillation suppression capability; however, this capability is significantly affected by the control structure. Existing research typically focuses on impedance reshaping only for a single frequency band, and the oscillation suppression effect of existing impedance reshaping controls varies across different oscillation frequency bands, making it difficult for current impedance reshaping control technologies to achieve superior broadband oscillation suppression capabilities across a wide frequency range. Specifically, the mechanism of traditional virtual parallel impedance control is to feed the oscillating voltage component forward to the current reference value through a virtual impedance, which can effectively suppress subsynchronous / supersynchronous oscillations in renewable energy grid-connected systems. However, due to the limitation of the actual SVG current loop bandwidth, the current PI controller cannot effectively respond to the mid-to-high frequency oscillation voltage component, thus limiting the mid-to-high frequency oscillation suppression capability. Correspondingly, the mechanism of traditional virtual series impedance control is to feed the oscillating current component forward to the modulation signal through a virtual impedance, which essentially increases the impedance amplitude of the SVG, avoiding opening the system resonance point and effectively suppressing mid-to-high frequency oscillations in renewable energy grid-connected systems. However, the impedance amplitude change of the SVG in the subsynchronous / supersynchronous frequency band has a relatively low impact on the overall impedance amplitude of the renewable energy power station, making it difficult to effectively solve the oscillation problem in the subsynchronous / supersynchronous frequency band. Therefore, there is an urgent need for an SVG control method that can suppress wideband oscillations in order to improve the operational reliability of new energy grid-connected systems.

[0004] In summary, since different virtual impedance control structures of SVG have limited ability to suppress oscillations in different frequency bands, existing technologies using a single virtual impedance control structure may not be able to provide sufficient positive damping for new energy grid-connected systems over a wide frequency range. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide an SVG virtual impedance adaptive switching control method and system to effectively suppress the oscillation problem in the wide frequency range of new energy power stations, in order to address the shortcomings of the existing technology.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: an SVG virtual impedance adaptive switching control, comprising the following steps:

[0007] 1) Collect the three-phase voltage V at the grid connection point of the new energy power station. a v b v c and three-phase current i a i b i c These are respectively input into the virtual parallel impedance and virtual series impedance control loops;

[0008] 2) Three-phase voltage v a v b v c The output after the virtual parallel impedance control stage is :

[0009]

[0010] in: For three-phase voltage signals, G N (s) is the transfer function of the fundamental frequency notch filter. , This is the damping coefficient of the notch filter. s is the fundamental angular frequency, s is the complex frequency, and G is the fundamental frequency. R (s) is the damping correction transfer function. , For the damping ratio, R is the natural frequency. v For parallel virtual impedance;

[0011] 3) Three-phase current i a i b i c The output after the virtual series impedance control stage :

[0012]

[0013] in: For three-phase current signals, G S (s) is the transfer function of the bandpass filter. , This represents the damping coefficient of the bandpass filter. Z is the center frequency of the bandpass filter. v For series virtual impedance;

[0014] 4) Output the virtual parallel control loop Perform an abc / dq transformation to obtain i dr i qr Output of virtual series control loop Perform an abc / dq transformation to obtain v dr v qr ;

[0015] 5) The three-phase voltage is input to the online oscillation detection module, which consists of variational mode decomposition (VMD) and Hilbert transform (HT). After VMD, the input voltage signal yields n intrinsic mode function (IMF) components. k (k=1,2,...,n), for each intrinsic mode component (IMF) k Perform HT, and record the result as H. k Then, the analytic signal is reconstructed using Euler's formula to obtain U. k :

[0016]

[0017] Will U k Converting to modulus and argument form, the amplitude, phase, and frequency information are obtained as follows:

[0018]

[0019] Among them: A k (t) represents the instantaneous amplitude, ϕ k (t) represents the instantaneous phase, f k (t) represents the instantaneous frequency. When the detected frequency is f... k If the voltage amplitude is greater than 5% of the fundamental frequency voltage amplitude, then the new energy grid-connected system is judged to be oscillating and the oscillation frequency is f. k Determine f k Is it greater than 2f1, where f1 is the fundamental frequency? If it is greater, the output voltage compensation is the output voltage of the virtual series impedance control circuit. dr v qr Current compensation amount i dr i qr Set to zero; otherwise, the voltage compensation amount v dr v qr Set to zero, the output current compensation is the output i of the virtual parallel impedance control loop. dr i qrCompared to the traditional FFT algorithm, which requires searching for oscillation peaks across a wide frequency spectrum to identify frequency points where the amplitude exceeds a threshold when monitoring oscillations, the VMD algorithm directly decomposes the original signal into several intrinsic mode components (IMFs). Each valid IMF corresponds to a potential oscillation mode. HT only needs to process these separated IMFs to directly and accurately extract their instantaneous amplitude, frequency, and phase information.

[0020] 6) Output compensation amount i dr i qr v dr v qr In the SVG dual-loop control structure, the output modulation signal of the SVG dual-loop control is: ;

[0021] Where: K d K is the dq current decoupling term. d =ω1L f L f G is the filter inductance value of the SVG. i (s) is a current PI controller, i dref and i qref i represents the current command value output by the SVG outer loop control. d and i q The dq component of the SVG output current;

[0022] 7) For the modulation signal c in the dq coordinate system d c q Perform the dq / abc transformation to obtain c. a c b c c The output c of the superimposed phase equalization control xa c xb c xc Then, the final modulation signal m is obtained. a m b m c Output m a m b m c To the SVG, control its output voltage and output current; m a =c a +c xa m b =c b +c xb m c =c c +c xc .

[0023] Output c of phase-to-phase voltage equalization control xa cxb c xc The calculation formula is:

[0024] ;

[0025] Among them, v ref The given value for the SVG capacitor voltage, v dca_sum v dcb_sum v dcc_sum These represent the sum of the capacitor voltages of all submodules in each phase arm of the SVG three-phase bridge arm, and H. x (s) and K are the outer loop PI controller and inner loop proportional coefficient in the phase-to-phase voltage equalization control, respectively. d θ represents the d-axis component of the SVG output current. PLL This is the phase-locked angle output by the phase-locked loop in the SVG.

[0026] This invention, by monitoring the system's oscillation frequency characteristics in real time, can automatically identify the currently dominant oscillation frequency band and adaptively switch to a preset virtual impedance control mode optimal for that frequency band, thereby achieving precise suppression through "one machine, multiple strategies, and on-demand deployment." For the oscillation characteristics of different frequency bands (such as subsynchronous, supersynchronous, and mid-frequency bands), this invention pre-sets two virtual impedance control loops in the control structure to ensure superior damping effects in each target frequency band. This method uses the output of the virtual impedance loop as a compensation quantity to compensate for the SVG's original dual-closed-loop control structure, achieving oscillation suppression without changing the SVG's basic control architecture. This invention effectively solves the shortcomings of a single virtual impedance method in adapting to the oscillation suppression requirements of multiple frequency bands and operating conditions, significantly improving the robustness and stability of the SVG in complex power grid environments.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention provides an SVG virtual impedance adaptive switching control to suppress broadband oscillations, which can invest appropriate virtual impedance control links for oscillation problems in different frequency bands and output corresponding compensation amounts to the dual closed-loop control structure of the SVG, so that the SVG can obtain a better oscillation suppression control effect when oscillations occur at different frequencies. Attached Figure Description

[0028] Figure 1 This is an embodiment of the new energy power station topology containing SVG according to the present invention;

[0029] Figure 2 This is a block diagram of an SVG virtual impedance adaptive switching control for suppressing broadband oscillations according to an embodiment of the present invention;

[0030] Figure 3 This is an example of the effect of an online oscillation monitoring module according to an embodiment of the present invention. Figure 3(a) shows the monitoring results during 65Hz oscillation. Figure 3 (b) shows the monitoring results during 125Hz oscillation;

[0031] Figure 4 This is an impedance Bode diagram of a new energy power station grid-connected system containing SVG according to an embodiment of the present invention. Figure 4 (a) Bode plots of the system impedance of the SVG using conventional control, fixed virtual series impedance control and the control proposed in this invention when 65Hz oscillation occurs; Figure 4 (b) Bode plots of the system impedance of the SVG using conventional control, fixed virtual parallel impedance control and the control proposed in this invention when 125Hz oscillation occurs;

[0032] Figure 5 This is a diagram showing the grid connection point current waveform and the q-axis current waveform of the SVG under fixed virtual series impedance control and virtual impedance adaptive switching control when a new energy power station experiences subsynchronous / supersynchronous oscillations, according to an embodiment of the present invention.

[0033] Figure 6 This is a diagram showing the grid connection point current waveform and the q-axis current waveform of the SVG under fixed virtual parallel impedance control and virtual impedance adaptive switching control when a new energy power station experiences medium-frequency oscillation, according to an embodiment of the present invention. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Example 1

[0036] Figure 1 The topology of the new energy power station (new energy grid-connected system) with SVG in Embodiment 1 of the present invention includes direct-drive wind turbine units Y1-Y 15 Box-type transformer T1-T 15 Internal collection lines and main transformer T m The direct-drive wind turbine is connected to the 35kV feeder via a box-type transformer, and the cascaded SVG is connected to the 35kV busbar of the renewable energy power station. g Y is the equivalent impedance of the power grid on the 35kV side. w For the frequency coupling admittance of the new energy power station, Y svg This is the frequency coupling admittance of the SVG.

[0037] like Figure 2As shown in the figure, an SVG virtual impedance adaptive switching control block diagram for suppressing broadband oscillations according to an embodiment of the present invention includes the following steps:

[0038] 1) Collect the three-phase voltage V at the grid connection point of the new energy power station. a v b v c and three-phase current i a i b i c These are respectively input into the virtual parallel impedance and virtual series impedance control loops.

[0039] 2) Three-phase voltage v a v b v c The output after the virtual parallel impedance control stage is :

[0040]

[0041] in: For three-phase voltage signals, G N (s) is the transfer function of the fundamental frequency notch filter. , This is the damping coefficient of the notch filter. s is the fundamental angular frequency, s is the complex frequency, and G is the fundamental frequency. R (s) is the damping correction transfer function. , For the damping ratio, R is the natural frequency. v This is a parallel virtual impedance.

[0042] 3) Three-phase current i a i b i c The output after the virtual series impedance control stage :

[0043]

[0044] in: For three-phase current signals, G S (s) is the transfer function of the bandpass filter. , This represents the damping coefficient of the bandpass filter. Z is the center frequency of the bandpass filter. v This is a series virtual impedance.

[0045] 4) Output the virtual parallel control loop Perform an abc / dq transformation to obtain i dr i qr Output of virtual series control loop Perform an abc / dq transformation to obtain v dr v qr .

[0046] 5) The three-phase voltage is input to the online oscillation detection module, which consists of variational mode decomposition (VMD) and Hilbert transform (HT). After VMD, the input voltage signal yields n intrinsic mode function (IMF) components. k (k=1,2,...,n), for each intrinsic mode component (IMF) k Perform HT, and record the result as H. k Then, the analytic signal is reconstructed using Euler's formula to obtain U. k :

[0047] ;

[0048] Will U k Converting to modulus and argument form, the amplitude, phase, and frequency information are obtained as follows:

[0049] Among them: A k (t) represents the instantaneous amplitude, ϕ k (t) represents the instantaneous phase, f k (t) represents the instantaneous frequency. When the detected frequency is f... k If the voltage amplitude is greater than 5% of the fundamental frequency voltage amplitude, then the new energy grid-connected system is judged to be oscillating and the oscillation frequency is f. k Determine f k Is it greater than 2f1, where f1 is the fundamental frequency? If it is greater, then the voltage compensation amount is the output v of the virtual series impedance control loop. dr v qr Current compensation amount i dr i qr Set to zero; otherwise, the voltage compensation amount v dr v qr Set to zero, the current compensation amount is the output i of the virtual parallel impedance control loop. dr i qr . Figure 3 As shown in (a), when a 65Hz oscillation occurs, VMD decomposes it into three intrinsic modes: a 65Hz oscillation component, a coupled 35Hz oscillation component, and a fundamental frequency component. The amplitude of the 65Hz oscillation component is 5% of the amplitude of the fundamental frequency voltage, which is determined to be a 65Hz system oscillation. Figure 3(b) shows that when a 125Hz oscillation occurs, the VMD decomposes it into three intrinsic modes: a 125Hz oscillation component, a coupled 25Hz oscillation component, and a fundamental frequency component. The amplitude of the 125Hz oscillation component is 8% of the amplitude of the fundamental frequency voltage, which is determined to be a 125Hz system oscillation.

[0050] 6) Output compensation amount i dr i qr v dr v qr In the SVG dual-loop control structure, the output modulation signal of the SVG dual-loop control is: ;

[0051] Where: K d K is the dq current decoupling term. d =ω1L f L f G is the filter inductance value of the SVG. i (s) is a current PI controller, i dref and i qref i represents the current command value output by the SVG outer loop control. d and i q The dq component of the SVG output current;

[0052] 7) For the modulation signal c in the dq coordinate system d c q Perform the dq / abc transformation to obtain c. a c b c c The output c of the superimposed phase equalization control xa c xb c xc Then, the final modulation signal m is obtained. a m b m c Output m a m b m c To the SVG, control its output voltage and output current; m a =c a +c xa m b =c b +c xb m c =c c +c xc .

[0053] Figure 4 (a) and Figure 4 (b) is the impedance Bode plot of the grid-connected system of a new energy power station containing SVG in Embodiment 1 of the present invention. Figure 4(a) When 65Hz oscillation occurs, the SVG uses traditional control, fixed virtual impedance control and the control proposed in the embodiment of the present invention. When using traditional control, the phase difference between the grid impedance and the system is 181° and the phase margin is -1°, resulting in system instability. When using fixed virtual series impedance control, the phase difference between the system and the system is 179° and the phase margin is 1°, resulting in system stability but insufficient damping. When the control proposed in the embodiment of the present invention is switched to the virtual parallel impedance control system, the phase difference is 160° and the phase margin is 20°, resulting in higher system stability margin. Figure 4 (b) When the 125Hz oscillation occurs, the SVG uses traditional control, fixed virtual impedance control and the control proposed in the embodiment of the present invention. When using traditional control, the phase difference between the grid impedance and the system is 181° and the phase margin is -1°, resulting in system instability. When using fixed virtual parallel impedance control, the phase difference between the system and the system is 176° and the phase margin is 4°, resulting in system stability but insufficient damping. When the control proposed in the embodiment of the present invention is switched to the virtual series impedance control system, the phase difference is 168° and the phase margin is 12°, resulting in higher system stability margin.

[0054] Figure 5 This is a diagram showing the grid-connected point current waveform and the q-axis current waveform of the SVG under traditional virtual series impedance control and virtual impedance adaptive switching control when a new energy power station experiences subsynchronous / supersynchronous oscillations, according to an embodiment of the present invention. Figure 5 It is known that traditional virtual series impedance control cannot achieve strong damping in the system, resulting in a long oscillation time of the grid-connected current. The q-axis current waveform of the SVG shows a weakened ability to absorb oscillation energy, leading to insufficient oscillation suppression. In the control structure of this embodiment, the SVG exhibits greater oscillation energy absorption capability, and system oscillation is suppressed more quickly, demonstrating the effectiveness of the control method of this embodiment. Figure 6 This is a diagram showing the grid-connected point current waveform and the q-axis current waveform of the SVG under traditional virtual parallel impedance control and virtual impedance adaptive switching control when a new energy power station experiences medium-frequency oscillation, according to an embodiment of the present invention. Figure 6 It can be seen that the system oscillation problem is suppressed to a certain extent under the traditional virtual parallel impedance control, while the oscillation suppression speed is faster under the control structure of the present invention embodiment, which proves the superiority of the control method of the present invention embodiment.

[0055] Example 2

[0056] Embodiment 2 of the present invention provides a control system corresponding to Embodiment 1 above, including a memory, a processor and a computer program stored in the memory; the processor executes the computer program in the memory to implement the steps of the method of Embodiment 1 above.

[0057] In some implementations, the memory may be high-speed random access memory (RAM), and may also include non-volatile memory, such as at least one disk storage device.

[0058] In other implementations, the processor can be any type of general-purpose processor, such as a central processing unit (CPU) or a digital signal processor (DSP), and there is no limitation here.

[0059] Example 3

[0060] Embodiment 3 of the present invention provides a computer-readable storage medium corresponding to Embodiment 1 above, on which a computer program / instructions are stored. When the computer program / instructions are executed by a processor, they implement the steps of the method of Embodiment 1 above.

[0061] A computer-readable storage medium can be a tangible device that holds and stores instructions for use by an instruction execution device. A computer-readable storage medium can be, for example, but not limited to, an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any combination thereof.

[0062] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. The solutions in the embodiments of this application can be implemented in various computer languages, such as the object-oriented programming language Java and the interpreted scripting language JavaScript.

[0063] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0064] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0065] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0066] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A method for adaptive switching control of SVG virtual impedance, characterized in that, comprising the steps of: S1, collect the three-phase voltage v of the new energy station grid-connected point a , b , c and three-phase current i a , b , c ; S2, the three-phase voltage v a , v b , v c Through the virtual parallel control impedance link, output three-phase current compensation quantity ; the three-phase current i a , i b , i c Through the virtual series control impedance link, output three-phase voltage compensation quantity ; ; S3, to performing an abc / dq transform to obtain i dr , i qr ; to performing an abc / dq transform to obtain v dr , v qr ; S4, performing variational mode decomposition on the three-phase voltage to obtain n intrinsic mode function components, for each intrinsic mode component IMF k performing Hilbert transform to obtain voltage amplitude; when monitoring that the voltage amplitude with frequency f k is greater than 5% of the fundamental frequency voltage amplitude, it is judged that the new energy grid-connected system is oscillating and the oscillation frequency is f k ; whether f k is greater than 2f1, if greater, the output voltage compensation quantity is the output v dr , v qr of the virtual series impedance control link, the current compensation quantity i dr , i qr is zero; otherwise, the voltage compensation quantity v dr , v qr is zero, and the output current compensation quantity is the output i dr , i qr of the virtual parallel impedance control link; f1 is the fundamental frequency, and k=1, 2,..., n; S5, obtaining the compensation quantity i in the dq coordinate system of SVG by using the compensation quantity i in the αβ coordinate system obtained in step S4 dr qr dr qr obtaining the modulation signal c in the dq coordinate system of SVG d q ;​​​​ S6, modulating signal c in dq coordinate system d q dq / abc transformation is performed to obtain c a b c , output c of the interphase voltage sharing control is superimposed xa xb xc , the final modulating signal m is obtained a b c , output m a b c to the SVG to control its output voltage and output current.​​​​​​​​​ 2. The SVG virtual impedance adaptive switching control method of claim 1, wherein, Three-phase current compensation amount The calculation formula is: ； where G N (s) is a base frequency notch filter transfer function, G R (s) is a damping correction transfer function, R v is a parallel virtual impedance.

3. The SVG virtual impedance adaptive switching control method of claim 2, wherein, , is the notch filter damping coefficient, is the fundamental angular frequency, s is the complex frequency.

4. The SVG virtual impedance adaptive switching control method of claim 2, wherein, , is the damping ratio, is the natural frequency, s is the complex frequency.

5. The SVG virtual impedance adaptive switching control method of claim 1, wherein, Three-phase current compensation amount The calculation formula is: ； where G N (s) is a baseband notch filter transfer function, G S (s) is a bandpass filter transfer function, Z v is a series virtual impedance.

6. The SVG virtual impedance adaptive switching control method of claim 5, wherein, , is the band pass filter damping coefficient, is the band pass filter center frequency.

7. The SVG virtual impedance adaptive switching control method of claim 1, wherein, SVG double closed-loop control output modulation signal c d , c q The calculation formula is: ； wherein K d is a dq current decoupling term, K d = ω1L f , L f is a filter inductance value of the SVG, G i (s) is a current PI controller, i dref and i qref are d-axis and q-axis current command values output by the outer loop control of the SVG, i d and i q are d-axis and q-axis components of the SVG output current.

8. The SVG virtual impedance adaptive switching control method of claim 1, wherein, Output c of the interphase voltage equalization control xa , c xb , c xc The calculation formula is: ； wherein v ref is the given value of the cascade H-bridge SVG submodule capacitor voltage, v dca_sum , v dcb_sum , v dcc_sum are the voltages of all submodules in each phase of the SVG three-phase bridge arm, H x (s) and K are the outer loop PI controller and the inner loop proportional coefficient in the interphase voltage balancing control, i d is the d-axis component of the SVG output current, θ PLL is the phase-locked angle output by the phase-locked loop in the SVG.

9. The SVG virtual impedance adaptive switching control method according to one of claims 1 to 8, characterized in that, The oscillation frequency of the SVG at time t is f k The formula for calculating (t) is: ;in, ; A k (t) represents the instantaneous amplitude at time t, ϕ k (t) represents the instantaneous phase at time t. Let be the k-th eigenmode function component at time t. For time t, the k-th eigenmode function component The result after performing the Hilbert transform.

10. An SVG virtual impedance adaptive switching control system comprising a memory, a processor and a computer program stored on the memory; characterized by, The processor executes the computer program to implement the steps of the method of any one of claims 1-9.

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