A damping control method and system for an impedance remodelling based solid state transformer

Abstract

The application discloses a damping control method and system of a solid-state transformer based on impedance remodeling, and the method comprises the following steps: collecting three-phase currents of a grid-side filter of the SST and converting the three-phase currents into current components in a dq coordinate system; constructing an impedance remodeling controller and dynamically optimizing and adjusting parameters of the impedance remodeling controller; operating input adjustment and generating a damping current reference instruction; and superimposing the damping current reference instruction on a current reference instruction output by a power loop or a voltage loop of the SST. The application solves the problems that a damping control scheme of introducing fixed loss by connecting a physical resistor in series or parallel with the SST filter, and the damping characteristic is single and difficult to adapt to grid dynamic changes and wide-frequency oscillation.

Description

Technical Field

[0001] This invention relates to the field of solid-state transformer damping control technology, specifically a damping control method and system for solid-state transformers based on impedance reshaping. Background Technology

[0002] With the high proportion of renewable energy integration and the rapid development of DC distribution networks, solid-state transformers (SSTs), as a new generation of intelligent power conversion hubs, are finding increasingly wider applications. However, SSTs are typically connected to the AC grid via LCL or LLCL filters. Their internal control loops (such as phase-locked loops, power loops, and current loops) interact complexly with the grid impedance, which can easily lead to significant oscillation and instability problems over a wide frequency range from tens of hertz to thousands of hertz.

[0003] To address the aforementioned issues, existing technologies primarily employ damping control by connecting physical resistors in series or parallel within the SST filter. While this damping control method is simple and reliable, it introduces fixed losses, reducing the overall efficiency of the SST and the power system it is connected to. Furthermore, its damping characteristics are limited, making it difficult to adapt to dynamic changes in grid conditions and the need to suppress wideband oscillations. Summary of the Invention

[0004] To address the aforementioned shortcomings, this invention proposes a damping control method and system based on impedance reshaping of solid-state transformers. The aim is to solve the problems of existing damping control schemes that introduce fixed losses by connecting physical resistors in series or parallel in SST filters, and the single damping characteristics that are difficult to adapt to dynamic changes and wide-frequency oscillations of the power grid.

[0005] To achieve this objective, the present invention adopts the following technical solution: A damping control method for a solid-state transformer based on impedance reshaping includes the following steps: Step S1: Collect the three-phase voltage at the grid-side filter connection point of the solid-state transformer SST. and three-phase current and respectively and Voltage components converted to dq coordinate system and current components ; Step S2: For each and Spectral analysis was performed to identify frequency components with amplitudes higher than the background noise and showing an increasing trend, in order to construct a set of frequencies at risk of oscillation. ; Step S3: Construct the desired impedance model and calculate the desired output impedance of the current SST in the dq coordinate system based on the desired impedance model. ; Step S4: Calculate the approximate output impedance of the current SST in the dq coordinate system using the micro-perturbation method or the model-based open-loop estimation method. ; Step S5: According to and The impedance deviation was calculated. ,in, The specific calculation formula is as follows: ; Where s represents the complex frequency domain operator, j Represents the imaginary unit, Represents angular frequency. ; Step S6: Constructing an impedance reshaping controller And dynamically adjust according to impedance deviation. The parameters make the following possible It can produce targeted damping effects at various oscillation risk frequencies; Step S7: [The sentence is incomplete and requires more context to be translated accurately.] Input adjusted Perform calculations to generate a damping current reference command. ,in, The specific mathematical expression is as follows: ; Step S8: Obtain the current reference command output by the SST power loop or voltage loop. and based on and The total reference command of the SST current loop is calculated. To achieve damping control of SST; among which, The specific calculation formula is as follows: .

[0006] Preferably, in step S3, the desired output impedance of the current SST in the dq coordinate system is... The specific calculation formula is as follows: ; in, ; Indicates the virtual fundamental frequency resistance; Indicates the virtual baseband inductance; Indicates adjustable gain; Indicates the damping ratio; Indicates the target angular frequency.

[0007] Preferably, in step S4, the approximate output impedance of the current SST in the dq coordinate system is calculated using the micro-perturbation method. Specifically, it includes the following sub-steps: Step S41: Obtain the current reference command output by the SST current loop, and superimpose the disturbance current signal onto the current reference command. ; Step S42: At the grid connection point of the SST grid-side filter, obtain the change in response voltage caused by the superimposed disturbance current signal. ; Step S43: According to and The approximate output impedance of the current SST in the dq coordinate system is calculated. ,in, The specific calculation formula is as follows: ; The approximate output impedance of the current SST in the dq coordinate system is calculated using a model-based open-loop estimation method. Specifically, it includes the following sub-steps: Step S44: Obtain the parameters of the main power circuit of SST and the parameters of each controller in the control loop of SST; Step S45: Based on the parameters of the SST main power circuit and the parameters of each controller in the SST control loop, construct a mathematical model of the SST output impedance. Step S46: Calculate the angular frequencies Input the SST output impedance mathematical model and calculate the impedance at the corresponding angular frequency. .

[0008] Preferably, in step S6, the impedance reshaping controller The mathematical expression in the dq coordinate system is as follows: ; Where n represents the total number of oscillation risk frequencies in the set of oscillation risk frequencies; This represents the reshaping gain corresponding to the i-th oscillation risk frequency; This represents the center angular frequency corresponding to the i-th oscillation risk frequency; This represents the damping ratio corresponding to the i-th oscillation risk frequency.

[0009] Another aspect of this application provides a damping control system based on impedance reshaping of a solid-state transformer, the system comprising: The acquisition module is used to acquire the three-phase voltage at the grid-side filter connection point of the solid-state transformer (SST). and three-phase current ; The conversion module is used to convert the data into the desired format. and Voltage components converted to dq coordinate system and current components ; The spectrum analysis and identification module is used to analyze and identify the spectrum of the spectrum. and Spectral analysis was performed to identify frequency components with amplitudes higher than the background noise and showing an increasing trend, in order to construct a set of frequencies at risk of oscillation. ; The first building block is used to construct the desired impedance model; The first calculation module is used to calculate the expected output impedance of the current SST in the dq coordinate system based on the expected impedance model. ; The second calculation module is used to calculate the approximate output impedance of the current SST in the dq coordinate system using either the micro-perturbation method or a model-based open-loop estimation method. ; The third calculation module is used to calculate based on... and The impedance deviation was calculated. ,in, The specific calculation formula is as follows: ; Where s represents the complex frequency domain operator, j Represents the imaginary unit, Represents angular frequency. ; The second building block is used to build the impedance reshaping controller. ; The parameter adjustment module is used to dynamically adjust the impedance based on the impedance deviation. The parameters make the following possible It can produce targeted damping effects at various oscillation risk frequencies; The generation module is used to generate Input adjusted Perform calculations to generate a damping current reference command. ,in, The specific mathematical expression is as follows: ; The acquisition module is used to acquire the current reference command output by the SST power loop or voltage loop. ; The fourth calculation module is used for... and The total reference command of the SST current loop is calculated. To achieve damping control of SST; among which, The specific calculation formula is as follows: .

[0010] Preferably, in the first calculation module, the expected output impedance of the current SST in the dq coordinate system is... The specific calculation formula is as follows: ; in, ; Indicates the virtual fundamental frequency resistance; Indicates the virtual baseband inductance; Indicates adjustable gain; Indicates the damping ratio; Indicates the target angular frequency.

[0011] Preferably, the second calculation module includes: The first acquisition submodule is used to acquire the current reference command output by the SST current loop and superimpose a disturbance current signal onto the current reference command. ; The second acquisition submodule is used to acquire the change in response voltage caused by the superimposed disturbance current signal at the grid connection point of the SST grid-side filter. ; The first calculation submodule is used to calculate based on... and The approximate output impedance of the current SST in the dq coordinate system is calculated. ,in, The specific calculation formula is as follows: ; The approximate output impedance of the current SST in the dq coordinate system is calculated using a model-based open-loop estimation method. Specifically, it includes the following sub-steps: The third acquisition submodule is used to acquire the parameters of the SST main power circuit and the parameters of each controller in the SST control loop; Construct a submodule to build a mathematical model of the SST output impedance based on the parameters of the SST main power circuit and the parameters of each controller in the SST control loop. The second calculation submodule is used to calculate each angular frequency. Input the SST output impedance mathematical model and calculate the impedance at the corresponding angular frequency. .

[0012] Preferably, in the second building block, the impedance reshaping controller The mathematical expression in the dq coordinate system is as follows: ; Where n represents the total number of oscillation risk frequencies in the set of oscillation risk frequencies; This represents the reshaping gain corresponding to the i-th oscillation risk frequency; This represents the center angular frequency corresponding to the i-th oscillation risk frequency; This represents the damping ratio corresponding to the i-th oscillation risk frequency.

[0013] The technical solution provided by this invention may include the following beneficial effects: In this scheme, the three-phase current at the grid-connected point of the SST grid-side filter is first collected. and will Current components converted to dq coordinate system Subsequently, an impedance reshaping controller was constructed. And its parameters are dynamically optimized and adjusted, and then... Input adjusted The process involves calculating and generating a damping current reference command, which is then superimposed on the current reference command output by the SST power loop or voltage loop to achieve damping control of the SST. Compared to existing damping control schemes that use physical resistors connected in series or parallel within the SST filter, this scheme employs an active damping control strategy. It eliminates the need for additional physical resistors, avoids introducing fixed losses, and improves the overall efficiency of the SST and the power system it is connected to. Furthermore, by optimizing the parameters of the impedance reshaping controller, it can provide targeted damping at various oscillation risk frequencies, effectively suppressing wideband, multi-mode oscillations from subsynchronous to supersynchronous. Attached Figure Description

[0014] Figure 1 This is a flowchart of the steps of a damping control method for a solid-state transformer based on impedance reshaping. Detailed Implementation

[0015] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0016] A damping control method for a solid-state transformer based on impedance reshaping includes the following steps: Step S1: Collect the three-phase voltage at the grid-side filter connection point of the solid-state transformer SST. and three-phase current and respectively and Voltage components converted to dq coordinate system and current components ; Step S2: For each and Spectral analysis was performed to identify frequency components with amplitudes higher than the background noise and showing an increasing trend, in order to construct a set of frequencies at risk of oscillation. ; Step S3: Construct the desired impedance model and calculate the desired output impedance of the current SST in the dq coordinate system based on the desired impedance model. ; Step S4: Calculate the approximate output impedance of the current SST in the dq coordinate system using the micro-perturbation method or the model-based open-loop estimation method. ; Step S5: According to and The impedance deviation was calculated. ,in, The specific calculation formula is as follows: ; Where s represents the complex frequency domain operator, j Represents the imaginary unit, Represents angular frequency. ; Step S6: Constructing an impedance reshaping controller And dynamically adjust according to impedance deviation. The parameters make the following possible It can produce targeted damping effects at various oscillation risk frequencies; Step S7: [The sentence is incomplete and requires more context to be translated accurately.] Input adjusted Perform calculations to generate a damping current reference command. ,in, The specific mathematical expression is as follows: ; Step S8: Obtain the current reference command output by the SST power loop or voltage loop. and based on and The total reference command of the SST current loop is calculated. To achieve damping control of SST; among which, The specific calculation formula is as follows: .

[0017] This scheme proposes a damping control method for solid-state transformers based on impedance reshaping, such as... Figure 1 As shown, the first step is to collect the three-phase voltage at the grid-side filter connection point of the solid-state transformer (SST). and three-phase current and respectively and Voltage components converted to dq coordinate system and current components In this embodiment, the three-phase voltage at the grid-connected point of the grid-side filter of the solid-state transformer SST is collected. and three-phase current This provides a reliable data foundation for subsequent damping control. By separately... and Voltage components converted to dq coordinate system and current components This enables the decoupling of active and reactive components, reducing the computational complexity of subsequent spectrum analysis and damping control. Further explanation: the grid-side filter connection point of the SST refers to the common connection point (PCC) connecting the grid inductor and the grid in the LCL filter. The dq coordinate system is a synchronously rotating coordinate system. Its direct axis, the d-axis, always aligns with the direction of the grid voltage vector locked by the phase-locked loop; the quadrature axis, the q-axis, leads the d-axis by 90 degrees and rotates synchronously with the grid fundamental frequency, thus ensuring that the d / q axis components are DC at the fundamental frequency. The second step is to separately... and Spectral analysis was performed to identify frequency components with amplitudes higher than the background noise and showing an increasing trend, in order to construct a set of frequencies at risk of oscillation. In this embodiment, by... and Spectrum analysis can identify the oscillation risk frequencies that may cause instability in the SST and the power system it is connected to. By constructing a set of oscillation risk frequencies from the identified frequency components, a clear target frequency range is provided for subsequent adjustment of the impedance reshaping controller, avoiding blind adjustments. Furthermore, methods such as recursive Fourier transform, bandpass filter banks, or adaptive notch filters can be used to further analyze these frequencies. and The third step is to construct the desired impedance model and calculate the desired output impedance of the current SST in the dq coordinate system based on the desired impedance model. In this embodiment, by constructing an expected impedance model, the SST can exhibit highly damped equivalent parallel resonant circuit characteristics at each oscillation risk frequency, thereby actively absorbing the oscillation energy of the corresponding frequency band. By calculating the expected output impedance of the current SST in the dq coordinate system based on the expected impedance model, the ideal impedance characteristics that the SST and the power system it is connected to should possess in the oscillation risk frequency range can be clearly defined. The fourth step is to calculate the approximate output impedance of the current SST in the dq coordinate system using the micro-perturbation method or the model-based open-loop estimation method. In this embodiment, by employing the micro-perturbation method or the model-based open-loop estimation method to calculate the approximate output impedance of the current SST in the dq coordinate system, the actual output impedance characteristics of the SST can be evaluated online or offline, accurately reflecting the current dynamic characteristics of the SST and the power system it is connected to. Further explanation: the micro-perturbation method is an online, experimental impedance measurement method. The model-based open-loop estimation method is an offline, theoretically calculated impedance measurement method. The fifth step is based on... and The impedance deviation was calculated. ,in, The specific calculation formula is as follows: Where s represents the complex frequency domain operator, j Represents the imaginary unit, Represents angular frequency. In this embodiment, by calculating the impedance deviation, the difference between the approximate impedance and the desired impedance can be effectively quantified, accurately locating the oscillation risk frequency range requiring damping compensation, and providing direct feedback signals for subsequent adjustment of the impedance reshaping controller parameters. The sixth step is to construct the impedance reshaping controller. And dynamically adjust according to impedance deviation. The parameters make the following possible This embodiment can generate targeted damping at various oscillation risk frequencies. By constructing an impedance reshaping controller and dynamically optimizing its parameters based on impedance deviation, it ensures that the impedance reshaping controller generates high-gain damping at each oscillation risk frequency, effectively suppressing resonance in the corresponding frequency band. The seventh step is to... Input adjusted Perform calculations to generate a damping current reference command. ,in, The specific mathematical expression is as follows: In this embodiment, by... Input adjusted The first step generates a damping current reference command, which can be directly applied to the SST current loop to ensure the speed and effectiveness of the damping response. The eighth step is to obtain the current reference command output from the SST power loop or voltage loop. and based on and The total reference command of the SST current loop is calculated. To achieve damping control of SST; among which, The specific calculation formula is as follows: In this embodiment, by superimposing the generated damping current reference command onto the current reference command output by the SST power loop or voltage loop, the enhanced damping characteristics and normal operation functions are synergistically compatible without changing the original SST control architecture.

[0018] In this scheme, the three-phase current at the grid-connected point of the SST grid-side filter is first collected. and will Current components converted to dq coordinate system Subsequently, an impedance reshaping controller was constructed. And its parameters are dynamically optimized and adjusted, and then... Input adjusted The process involves calculating and generating a damping current reference command, which is then superimposed on the current reference command output by the SST power loop or voltage loop to achieve damping control of the SST. Compared to existing damping control schemes that use physical resistors connected in series or parallel within the SST filter, this scheme employs an active damping control strategy. It eliminates the need for additional physical resistors, avoids introducing fixed losses, and improves the overall efficiency of the SST and the power system it is connected to. Furthermore, by optimizing the parameters of the impedance reshaping controller, it can provide targeted damping at various oscillation risk frequencies, effectively suppressing wideband, multi-mode oscillations from subsynchronous to supersynchronous.

[0019] Preferably, in step S3, the desired output impedance of the current SST in the dq coordinate system is... The specific calculation formula is as follows: ; in, ; Indicates the virtual fundamental frequency resistance; Indicates the virtual baseband inductance; Indicates adjustable gain; Indicates the damping ratio; Indicates the target angular frequency.

[0020] In this embodiment, During the calculation, Used to provide fundamental damping at the fundamental frequency. Used to provide inertial support at the base frequency. As a virtual damping term, it can be applied at the target angular frequency. It provides targeted high-frequency damping to precisely suppress resonant oscillations in the corresponding frequency band, while also offering adjustable gain. Damping ratio It enables flexible configuration of damping strength.

[0021] Preferably, in step S4, the approximate output impedance of the current SST in the dq coordinate system is calculated using the micro-perturbation method. Specifically, it includes the following sub-steps: Step S41: Obtain the current reference command output by the SST current loop, and superimpose the disturbance current signal onto the current reference command. ; Step S42: At the grid connection point of the SST grid-side filter, obtain the change in response voltage caused by the superimposed disturbance current signal. ; Step S43: According to and The approximate output impedance of the current SST in the dq coordinate system is calculated. ,in, The specific calculation formula is as follows: ; The approximate output impedance of the current SST in the dq coordinate system is calculated using a model-based open-loop estimation method. Specifically, it includes the following sub-steps: Step S44: Obtain the parameters of the main power circuit of SST and the parameters of each controller in the control loop of SST; Step S45: Based on the parameters of the SST main power circuit and the parameters of each controller in the SST control loop, construct a mathematical model of the SST output impedance. Step S46: Calculate the angular frequencies Input the SST output impedance mathematical model and calculate the impedance at the corresponding angular frequency. .

[0022] In this embodiment, the micro-perturbation method is used for calculation. During the process, a disturbance current signal is superimposed on the original current reference command to provide an excitation source for impedance measurement. By obtaining the change in response voltage caused by the superimposed disturbance current signal at the grid connection point of the SST grid-side filter, the true physical response of the SST output impedance to the injected disturbance can be directly reflected, thus ensuring the accuracy of the impedance measurement. This is achieved by applying the formula… "Calculate" This ensures the reliability of the calculation results. The model-based open-loop estimation method is used to calculate... During the process, by acquiring the parameters of the SST's main power circuit and the parameters of each controller in the SST's control loop, a solid data foundation is provided for the subsequent construction of the SST output impedance mathematical model. Further explanation is needed: the parameters of the SST's main power circuit include the capacitance and inductance of the LCL filter. The parameters of each controller in the SST's control loop include the proportional gain and integral time constant of the current loop PI controller. By constructing the SST output impedance mathematical model, the influence of each circuit parameter and controller parameter on the impedance characteristics can be clearly revealed. This is achieved by using various angular frequencies... Input the SST output impedance mathematical model and obtain the corresponding angular frequency. This eliminates the need for real-time hardware testing, thereby improving the efficiency of impedance measurement.

[0023] Preferably, in step S6, the impedance reshaping controller The mathematical expression in the dq coordinate system is as follows: ; Where n represents the total number of oscillation risk frequencies in the set of oscillation risk frequencies; This represents the reshaping gain corresponding to the i-th oscillation risk frequency; This represents the center angular frequency corresponding to the i-th oscillation risk frequency; This represents the damping ratio corresponding to the i-th oscillation risk frequency.

[0024] In this embodiment, the impedance reshaping controller It is composed of multiple second-order resonant elements superimposed, and the center angular frequency of each resonant element is... Each frequency corresponds one-to-one with a frequency in the set of oscillation risk frequencies, achieving high gain at each risk frequency and enabling precise suppression of specific oscillating airflow. This is achieved by adjusting each resonant element. and The damping strength of the impedance reshaping controller at the corresponding risk frequency can be flexibly configured.

[0025] Another aspect of this application provides a damping control system based on impedance reshaping of a solid-state transformer, the system comprising: The acquisition module is used to acquire the three-phase voltage at the grid-side filter connection point of the solid-state transformer (SST). and three-phase current ; The conversion module is used to convert the data into the desired format. and Voltage components converted to dq coordinate system and current components ; The spectrum analysis and identification module is used to analyze and identify the spectrum of the spectrum. and Spectral analysis was performed to identify frequency components with amplitudes higher than the background noise and showing an increasing trend, in order to construct a set of frequencies at risk of oscillation. ; The first building block is used to construct the desired impedance model; The first calculation module is used to calculate the expected output impedance of the current SST in the dq coordinate system based on the expected impedance model. ; The second calculation module is used to calculate the approximate output impedance of the current SST in the dq coordinate system using either the micro-perturbation method or a model-based open-loop estimation method. ; The third calculation module is used to calculate based on... and The impedance deviation was calculated. ,in, The specific calculation formula is as follows: ; Where s represents the complex frequency domain operator, j Represents the imaginary unit, Represents angular frequency. ; The second building block is used to build the impedance reshaping controller. ; The parameter adjustment module is used to dynamically adjust the impedance based on the impedance deviation. The parameters make the following possible It can produce targeted damping effects at various oscillation risk frequencies; The generation module is used to generate Input adjusted Perform calculations to generate a damping current reference command. ,in, The specific mathematical expression is as follows: ; The acquisition module is used to acquire the current reference command output by the SST power loop or voltage loop. ; The fourth calculation module is used for... and The total reference command of the SST current loop is calculated. To achieve damping control of SST; among which, The specific calculation formula is as follows: .

[0026] This solution presents a damping control system for a solid-state transformer based on impedance reshaping. Through the mutual coordination of a data acquisition module, a conversion module, a spectrum analysis and identification module, a first construction module, a first calculation module, a second calculation module, a third calculation module, a second construction module, a parameter adjustment module, a generation module, an acquisition module, and a fourth calculation module, active damping control of the SST is achieved.

[0027] Preferably, in the first calculation module, the expected output impedance of the current SST in the dq coordinate system is... The specific calculation formula is as follows: ; in, ; Indicates the virtual fundamental frequency resistance; Indicates the virtual baseband inductance; Indicates adjustable gain; Indicates the damping ratio; Indicates the target angular frequency.

[0028] In this embodiment, in the first calculation module, Used to provide fundamental damping at the fundamental frequency. Used to provide inertial support at the base frequency. As a virtual damping term, it can be applied at the target angular frequency. It provides targeted high-frequency damping to precisely suppress resonant oscillations in the corresponding frequency band, while also offering adjustable gain. Damping ratio It enables flexible configuration of damping strength.

[0029] Preferably, the second calculation module includes: The first acquisition submodule is used to acquire the current reference command output by the SST current loop and superimpose a disturbance current signal onto the current reference command. ; The second acquisition submodule is used to acquire the change in response voltage caused by the superimposed disturbance current signal at the grid connection point of the SST grid-side filter. ; The first calculation submodule is used to calculate based on... and The approximate output impedance of the current SST in the dq coordinate system is calculated. ,in, The specific calculation formula is as follows: ; The approximate output impedance of the current SST in the dq coordinate system is calculated using a model-based open-loop estimation method. Specifically, it includes the following sub-steps: The third acquisition submodule is used to acquire the parameters of the SST main power circuit and the parameters of each controller in the SST control loop; Construct a submodule to build a mathematical model of the SST output impedance based on the parameters of the SST main power circuit and the parameters of each controller in the SST control loop. The second calculation submodule is used to calculate each angular frequency. Input the SST output impedance mathematical model and calculate the impedance at the corresponding angular frequency. .

[0030] In this embodiment, the micro-perturbation method is used for calculation. During the process, a first acquisition submodule is set up to provide an excitation source for impedance measurement. A second acquisition submodule is set up to directly reflect the true physical response of the SST output impedance to injected disturbances, thus ensuring the accuracy of the impedance measurement. A first calculation submodule is set up to ensure the reliability of the calculation results. A model-based open-loop estimation method is used for calculation... During the process, a third acquisition submodule was set up to provide a solid data foundation for the subsequent construction of the SST output impedance mathematical model. The construction submodule clearly reveals the influence of various circuit parameters and controller parameters on impedance characteristics. The second calculation submodule eliminates the need for real-time hardware testing, thereby improving the efficiency of impedance measurement.

[0031] Preferably, in the second building block, the impedance reshaping controller The mathematical expression in the dq coordinate system is as follows: ; Where n represents the total number of oscillation risk frequencies in the set of oscillation risk frequencies; This represents the reshaping gain corresponding to the i-th oscillation risk frequency; This represents the center angular frequency corresponding to the i-th oscillation risk frequency; This represents the damping ratio corresponding to the i-th oscillation risk frequency.

[0032] In this embodiment, in the second building module, the impedance reshaping controller It is composed of multiple second-order resonant elements superimposed, and the center angular frequency of each resonant element is... Each frequency corresponds one-to-one with a frequency in the set of oscillation risk frequencies, achieving high gain at each risk frequency and enabling precise suppression of specific oscillating airflow. This is achieved by adjusting each resonant element. and The damping strength of the impedance reshaping controller at the corresponding risk frequency can be flexibly configured.

[0033] Furthermore, the functional units in the various embodiments of the present invention can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0034] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A damping control method for a solid-state transformer based on impedance reshaping, characterized in that: Includes the following steps: Step S1: Collect the three-phase voltage at the grid-side filter connection point of the solid-state transformer SST. and three-phase current and respectively and Voltage components converted to dq coordinate system and current components ; Step S2: For each and Spectral analysis was performed to identify frequency components with amplitudes higher than the background noise and showing an increasing trend, in order to construct a set of frequencies at risk of oscillation. ; Step S3: Construct the desired impedance model and calculate the desired output impedance of the current SST in the dq coordinate system based on the desired impedance model. ; Step S4: Calculate the approximate output impedance of the current SST in the dq coordinate system using the micro-perturbation method or the model-based open-loop estimation method. ; Step S5: According to and The impedance deviation was calculated. ,in, The specific calculation formula is as follows: ； Where s represents the complex frequency domain operator, j Represents the imaginary unit, Represents angular frequency. ; Step S6: Constructing an impedance reshaping controller And dynamically adjust according to impedance deviation. The parameters make the following possible It can produce targeted damping effects at various oscillation risk frequencies; Step S7: [The sentence is incomplete and requires more context to be translated accurately.] Input adjusted Perform calculations to generate a damping current reference command. ,in, The specific mathematical expression is as follows: ； Step S8: Obtain the current reference command output by the SST power loop or voltage loop. and based on and The total reference command of the SST current loop is calculated. To achieve damping control of SST; among which, The specific calculation formula is as follows: 。 2. The damping control method for a solid-state transformer based on impedance reshaping according to claim 1, characterized in that: In step S3, the desired output impedance of the current SST in the dq coordinate system is... The specific calculation formula is as follows: ； in, ; Indicates the virtual fundamental frequency resistance; Indicates the virtual baseband inductance; Indicates adjustable gain; Indicates the damping ratio; Indicates the target angular frequency.

3. The damping control method for a solid-state transformer based on impedance reshaping according to claim 1, characterized in that: In step S4, the approximate output impedance of the current SST in the dq coordinate system is calculated using the micro-perturbation method. Specifically, it includes the following sub-steps: Step S41: Obtain the current reference command output by the SST current loop, and superimpose the disturbance current signal onto the current reference command. ; Step S42: At the grid connection point of the SST grid-side filter, obtain the change in response voltage caused by the superimposed disturbance current signal. ; Step S43: According to and The approximate output impedance of the current SST in the dq coordinate system is calculated. ,in, The specific calculation formula is as follows: ； The approximate output impedance of the current SST in the dq coordinate system is calculated using a model-based open-loop estimation method. Specifically, it includes the following sub-steps: Step S44: Obtain the parameters of the main power circuit of SST and the parameters of each controller in the control loop of SST; Step S45: Based on the parameters of the SST main power circuit and the parameters of each controller in the SST control loop, construct a mathematical model of the SST output impedance. Step S46: Calculate the angular frequencies Input the SST output impedance mathematical model and calculate the impedance at the corresponding angular frequency. .

4. The damping control method for a solid-state transformer based on impedance reshaping according to claim 1, characterized in that: In step S6, the impedance reshaping controller The mathematical expression in the dq coordinate system is as follows: ； Where n represents the total number of oscillation risk frequencies in the set of oscillation risk frequencies; This represents the reshaping gain corresponding to the i-th oscillation risk frequency; This represents the center angular frequency corresponding to the i-th oscillation risk frequency; This represents the damping ratio corresponding to the i-th oscillation risk frequency.

5. A damping control system for a solid-state transformer based on impedance reshaping, using the damping control method for a solid-state transformer based on impedance reshaping as described in any one of claims 1-4, characterized in that: The system includes: The acquisition module is used to acquire the three-phase voltage at the grid-side filter connection point of the solid-state transformer (SST). and three-phase current ; The conversion module is used to convert the data into the desired format. and Voltage components converted to dq coordinate system and current components ; The spectrum analysis and identification module is used to analyze and identify the spectrum of the spectrum. and Spectral analysis was performed to identify frequency components with amplitudes higher than the background noise and showing an increasing trend, in order to construct a set of frequencies at risk of oscillation. ; The first building block is used to construct the desired impedance model; The first calculation module is used to calculate the expected output impedance of the current SST in the dq coordinate system based on the expected impedance model. ; The second calculation module is used to calculate the approximate output impedance of the current SST in the dq coordinate system using either the micro-perturbation method or a model-based open-loop estimation method. ; The third calculation module is used to calculate based on... and The impedance deviation was calculated. ,in, The specific calculation formula is as follows: ； Where s represents the complex frequency domain operator, j Represents the imaginary unit, Represents angular frequency. ; The second building block is used to build the impedance reshaping controller. ; The parameter adjustment module is used to dynamically adjust the impedance based on the impedance deviation. The parameters make the following possible It can produce targeted damping effects at various oscillation risk frequencies; The generation module is used to generate Input adjusted Perform calculations to generate a damping current reference command. ,in, The specific mathematical expression is as follows: ； The acquisition module is used to acquire the current reference command output by the SST power loop or voltage loop. ; The fourth calculation module is used for... and The total reference command of the SST current loop is calculated. To achieve damping control of SST; among which, The specific calculation formula is as follows: 。 6. The damping control system for a solid-state transformer based on impedance reshaping according to claim 5, characterized in that: In the first calculation module, the expected output impedance of the current SST in the dq coordinate system The specific calculation formula is as follows: ； in, ; Indicates the virtual fundamental frequency resistance; Indicates the virtual baseband inductance; Indicates adjustable gain; Indicates the damping ratio; Indicates the target angular frequency.

7. A damping control system based on impedance reshaping of a solid-state transformer according to claim 5, characterized in that: The second calculation module includes: The first acquisition submodule is used to acquire the current reference command output by the SST current loop and superimpose a disturbance current signal onto the current reference command. ; The second acquisition submodule is used to acquire the change in response voltage caused by the superimposed disturbance current signal at the grid connection point of the SST grid-side filter. ; The first calculation submodule is used to calculate based on... and The approximate output impedance of the current SST in the dq coordinate system is calculated. ,in, The specific calculation formula is as follows: ； The approximate output impedance of the current SST in the dq coordinate system is calculated using a model-based open-loop estimation method. Specifically, it includes the following sub-steps: The third acquisition submodule is used to acquire the parameters of the SST main power circuit and the parameters of each controller in the SST control loop; Construct a submodule to build a mathematical model of the SST output impedance based on the parameters of the SST main power circuit and the parameters of each controller in the SST control loop. The second calculation submodule is used to calculate each angular frequency. Input the SST output impedance mathematical model and calculate the impedance at the corresponding angular frequency. .

8. A damping control system for a solid-state transformer based on impedance reshaping according to claim 5, characterized in that: In the second building block, the impedance reshaping controller The mathematical expression in the dq coordinate system is as follows: ； Where n represents the total number of oscillation risk frequencies in the set of oscillation risk frequencies; This represents the reshaping gain corresponding to the i-th oscillation risk frequency; This represents the center angular frequency corresponding to the i-th oscillation risk frequency; This represents the damping ratio corresponding to the i-th oscillation risk frequency.

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