Plug and play dc active damper based on adaptive stabilization control

Abstract

The present application relates to the technical field of direct current power distribution system stability control, and particularly relates to a plug-and-play type direct current active damper based on adaptive stability control, which is connected in parallel at a node of a direct current power distribution network system and comprises a main circuit and a control system; the main circuit adopts a bidirectional DC-DC converter topology, comprising a filter inductor, a half-bridge bridge arm composed of a first power switch tube and a second power switch tube, and a direct current side support capacitor; the control system adopts a double closed loop control architecture of a voltage outer ring and an inductor current inner ring and is integrated with an adaptive active damping control module. The direct current active damper of the present application does not need to rely on global system parameters or modify the control strategy of the original equipment, is connected in parallel in a multi-node direct current power distribution network system in a plug-and-play manner, takes into account physical hardware constraints and stability boundaries, can adaptively suppress bus voltage wide frequency oscillation caused by multi-device impedance interaction, and significantly improves the global stability and device compatibility of the direct current power distribution network system.

Description

Technical Field

[0001] This invention relates to the field of DC power distribution system stability control technology, specifically to a plug-and-play DC active damper based on adaptive stability control. Background Technology

[0002] In practical multi-converter DC distribution systems, distributed power sources, energy storage, and various constant power loads are typically interconnected through complex network topologies. As system scale increases and the number of grid-connected devices grows, not only does the system impedance interaction become more complex, but the coupling effect of line impedance also becomes increasingly significant, easily triggering broadband resonance and seriously threatening the safe and stable operation of the system. Especially as DC distribution network systems evolve towards multi-voltage levels, large capacity, and multi-microgrid interconnection, not only are local oscillations present at local nodes, but global broadband interactive resonance phenomena spanning long physical distances are also highly likely to occur. This places extremely stringent requirements on the system's wide-area coordinated control and the transient stability operating boundaries of the equipment.

[0003] Adaptive active damping control based on virtual impedance is remarkably effective in suppressing resonance in cascaded systems. However, in practical engineering applications, systems often contain numerous "black box" converters, making it difficult to directly modify the underlying control strategies of existing commercial load converters. DC active dampers, as independent auxiliary power electronic devices, can be flexibly integrated into the system's common coupling point or high-resonance nodes. They do not require intervention in the internal control loops of existing equipment, have minimal impact on existing equipment performance, offer greater flexibility, and truly achieve "plug and play."

[0004] In existing technologies, Scheme 1 proposes an adaptive active damper, making the converter equivalent to a virtual capacitor that adapts to power changes at the port, thereby improving system stability margin. Scheme 2 connects the active damper in parallel at the constant power load port, and through the design of voltage and current trajectory control strategies, makes the load dynamically equivalent to an adaptive intelligent resistor. Scheme 3 proposes to use an active auxiliary circuit to equivalently simulate a passive RC damping network, and by switching RC parameters under transient and steady-state conditions, achieve a balance between system stability and dynamic performance.

[0005] The applicant found that the aforementioned externally-connected active damping solutions still face some common technical challenges in practical applications. Existing devices often rely on preset offline parameters for damping strategies. When the DC distribution network topology is reconfigured or the number of connected devices changes, they often lack sufficient adaptive capability to capture the true resonance characteristics in real time. Because they cannot accurately identify and dynamically align oscillations over a wide frequency range, the suppression effect of the device under off-design conditions is significantly reduced, and new instability risks may even be introduced due to impedance mismatch. This severely limits the safe operating boundaries of active dampers in complex multi-node DC networks and their "plug-and-play" engineering application value. Summary of the Invention

[0006] To address the shortcomings of the existing technologies, the technical problem to be solved by this invention is: how to provide a plug-and-play DC active damper based on adaptive stability control, which does not rely on global system parameters or modify the control strategy of existing equipment, and can be connected in parallel to a multi-node DC distribution network system in a plug-and-play manner, taking into account both physical hardware constraints and stability boundaries, and can adaptively suppress the wide-band oscillation of bus voltage caused by impedance interaction of multiple devices, thus significantly improving the global stability and equipment compatibility of the DC distribution network system.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] A plug-and-play DC active damper based on adaptive stability control, wherein the DC active damper is connected in parallel at a node of a DC distribution network system, and includes a main circuit and a control system.

[0009] The main circuit adopts a bidirectional DC-DC converter topology, including a filter inductor, a half-bridge arm composed of a first power switch and a second power switch, and a DC-side support capacitor. One end of the filter inductor is connected to the positive terminal of the DC distribution network system bus, and the other end is connected between the first power switch and the second power switch. The other end of the first power switch, which is not connected to the filter inductor, is connected to the negative terminal of the DC distribution network system bus and the negative terminal of the DC-side support capacitor. The other end of the second power switch, which is not connected to the filter inductor, is connected to the positive terminal of the DC-side support capacitor.

[0010] The control system adopts a dual closed-loop control architecture with an outer voltage loop and an inner inductor current loop, and integrates an adaptive active damping control module.

[0011] The outer voltage loop is used to generate the base current setpoint through the voltage of the DC-side supporting capacitor;

[0012] The adaptive active damping control module is used to extract the AC disturbance component of the bus voltage of the DC distribution network system online, and generate the high-frequency resonant compensation current setpoint through parallel virtual impedance control;

[0013] The inner loop of the inductor current is used to generate control signals to drive the first power switch and the second power switch by filtering the inductor current, the base current setpoint, and the high-frequency resonant compensation current setpoint.

[0014] Preferably, the processing steps for the outer voltage loop include:

[0015] S11: Collect the DC-side support capacitor voltage and calculate the corresponding feedback signal;

[0016] S12: Compare the feedback signal of the DC-side support capacitor voltage with the set voltage reference and calculate the voltage error value;

[0017] S13: Input the voltage error value into the voltage regulator for processing, and then output the base current setpoint.

[0018] Preferably, the processing steps of the adaptive active damping control module include:

[0019] S21: Collect the bus voltage of the DC distribution network system and calculate the corresponding feedback signal;

[0020] S22: The resonant angular frequency is extracted by deconstructing the feedback signal of the DC distribution network system bus voltage through the resonant feature extraction unit. Harmonic amplitude ;

[0021] S23: Based on the resonant angular frequency Real-time locking of the center frequency of the virtual impedance The parameter adjuster is used according to the resonance amplitude. Dynamic calculation of damping gain Finally, the center frequency and damping gain The input bandpass virtual impedance transfer function generates the high-frequency resonant compensation current setpoint.

[0022] Preferably, in step S22, the resonant feature extraction unit is an improved second-order generalized integrator frequency-locked loop; the improved second-order generalized integrator frequency-locked loop outputs the resonant angular frequency based on the feedback signal of the DC distribution network system bus voltage. Simultaneously, the AC disturbance component of the DC distribution network system bus voltage is separated and extracted from the voltage feedback signal, and the resonant amplitude of the AC disturbance component is extracted. ;

[0023] Improvements to the frequency-locked loop of the improved second-order generalized integrator include:

[0024] (1) By introducing a DC suppression loop based on gradient descent method, the DC bias in the feedback signal of the bus voltage of the DC distribution network system is eliminated;

[0025] definition The cost function of the DC distribution network system is used to estimate the DC component. Revised to:

[0026] ;

[0027] By applying gradient descent to minimize the cost function, the integral update expression for the DC component estimate is obtained as follows:

[0028] ;

[0029] In the formula: This is an error signal; The feedback signal includes the resonant disturbance; for The estimated value of the AC disturbance component at the shaft output terminal, i.e., the AC disturbance component; This is the gain constant of the DC suppression loop;

[0030] (2) The expression for the estimation of the resonant angular frequency is modified into the following nonlinear expression through a soft-start mechanism:

[0031] ;

[0032] In the formula: The derivative of the resonant angular frequency; This is the gain coefficient; This is an estimate of the amplitude of the AC disturbance component; For design constants; This is an error signal; This is the voltage estimate at the quadrature axis output terminal;

[0033] (3) A convergence determination logic based on exponential moving average filtering is adopted to continuously monitor the resonant angular frequency of the frequency-locked loop output of the improved second-order generalized integrator, and lock it to the final resonant angular frequency when the resonant angular frequency converges:

[0034] (3.1) Introduce an exponential moving average filter to measure the resonant angular frequency of the real-time output. Smoothing is performed to obtain the smoothed frequency. ;

[0035] The discrete update expression for the exponential moving average filter is:

[0036] ;

[0037] In the formula: This represents the current discrete sampling time. This refers to the previous sampling time. These are the filtering smoothing coefficients, and ;

[0038] (3.2) Calculate the current resonant angular frequency in real time With smooth frequency absolute difference ;

[0039] (3.3) If the absolute difference continuous The values ​​are all less than the preset tolerance threshold within each calculation cycle. If the resonant angular frequency has converged, then the resonant angular frequency value at this moment is locked as the final resonant angular frequency. .

[0040] Preferably, in step S24, the processing steps of the virtual impedance generation unit include:

[0041] S241: Regarding the resonant angular frequency After standardization, it is directly mapped to the center frequency of the bandpass virtual impedance. ;

[0042] S242: Adjust the resonant amplitude The error input is fed into the gain regulator, and the gain coefficient of the virtual impedance is dynamically adjusted using a proportional-integral control algorithm. ;

[0043] S243: Center frequency and damping gain Input bandpass virtual impedance transfer function Reconstruct the virtual impedance;

[0044] The formula is expressed as:

[0045] ;

[0046] In the formula: For reconstructed virtual impedance; This represents the bandwidth corresponding to the virtual impedance at the -3dB cutoff frequency. Indicates damping gain; Indicates the center frequency;

[0047] S244: Generate high-frequency resonant compensation current setpoint based on reconstructed virtual impedance.

[0048] Preferably, the transfer function of an impedance compensation stage is inserted into the output feedforward path of the adaptive active damping control module. Pre-correction is performed on the setpoint of the high-frequency resonant compensation current;

[0049] Impedance compensation element transfer function Engineering design is simplified based on frequency band allocation principles, specifically including:

[0050] (1) Simplification of low frequency band: In the mid-to-high frequency resonant frequency band, the influence of the voltage outer loop with a lower cutoff frequency is ignored, and it is approximately assumed that , This represents the open-loop gain of the outer voltage loop.

[0051] (2) High-frequency band simplification: In the resonant frequency band within the cutoff frequency of the inner loop of the inductor current, the amplitude of the open-loop current gain is much greater than 1. It is approximately assumed that the transfer coefficient change caused by the state feedback term of the inner loop of the current tends to the ideal tracking state.

[0052] (3) Through simplification in the low-frequency band and simplification in the high-frequency band, the transfer function of the impedance compensation stage is... This is equivalent to a pure scaling constant related to the hardware sampling coefficients:

[0053] ;

[0054] In the formula: The current sampling feedback coefficient of the filter inductor; This represents the bus voltage sampling feedback coefficient of the DC distribution network system.

[0055] Preferably, the processing steps for the inner loop of the inductor current include:

[0056] S31: Acquire the filter inductor current and calculate the corresponding feedback signal;

[0057] S32: Add the base current setpoint to the high-frequency resonant compensation current setpoint to obtain the total current setpoint of the inner loop of the inductor current.

[0058] S33: Compare the total current setpoint with the feedback signal of the filter inductor current and calculate the current error value;

[0059] S34: After the current error value is input into the current regulator and pulse width modulation stage for processing, a control signal is generated to drive the first power switch and the second power switch.

[0060] Preferably, the bandwidth design of the control system follows the principle of frequency domain decoupling and dynamic tracking. The control bandwidth of the inner loop of the inductor current is set to 1 / 10 to 1 / 5 of the switching frequency of the first power switch and the second power switch. The control bandwidth of the outer loop of the voltage is lower than the bandwidth of the inner loop of the inductor current.

[0061] Preferably, the port equivalent admittance model of the DC active damper is as follows:

[0062] ;

[0063] ;

[0064] ;

[0065] In the formula: The port equivalent admittance of the DC active damper; The basic admittance determined by the dual closed-loop control; The input voltage sampling feedback coefficient; This is the closed-loop transfer function for inductor current. The transfer function for the impedance compensation stage; This is a bandpass virtual impedance transfer function; This represents the open-loop gain of the outer voltage loop. The input admittance transfer function under current closed-loop conditions; The input-output voltage transfer function under current closed-loop conditions; The transfer function from the inductor current to the output voltage; This is the voltage feedback coefficient; It is a voltage loop PI regulator.

[0066] Preferably, the parameter design of the DC active damper includes:

[0067] (1) Design of DC active damper capacity and energy storage capacitor voltage:

[0068] Set the steady-state voltage setpoint of the DC-side support capacitor. Greater than the maximum transient bus voltage at the node, satisfying , This refers to the rated bus voltage of the DC distribution network system.

[0069] Based on the minimum equivalent virtual admittance critical value required to maintain the global stability of the DC distribution network system Set the minimum apparent power capacity of the DC active damper. satisfy:

[0070] ;

[0071] In the formula: This refers to the rated bus voltage of the DC distribution network system. This represents the maximum expected range of the ratio of the target resonant voltage component to the rated DC voltage.

[0072] (2) Design of DC-side supporting capacitor:

[0073] Based on the limitation of voltage fluctuation caused by a single charge and discharge cycle of the capacitor due to resonant energy pulsation, a lower limit value is set for the DC-side supporting capacitor. for:

[0074] ;

[0075] In the formula: This is the steady-state bus voltage; The amplitude of the high-frequency resonant current absorbed by the DC active damper; The lowest angular frequency of the target resonant frequency band for the DC distribution network system; The allowable peak-to-peak value of capacitor voltage ripple;

[0076] (3) Filter inductor design:

[0077] Setting the filter inductor The range of values ​​is The upper and lower limits are respectively:

[0078] ;

[0079] ;

[0080] In the formula: The switching frequency; The maximum permissible high-frequency switching current ripple limit; This is the highest angular frequency in the system's target resonant frequency band.

[0081] Compared with existing technologies, the plug-and-play DC active damper based on adaptive stability control in this invention has the following advantages:

[0082] (1) This invention significantly improves the resonance suppression capability and robustness of DC active dampers under complex and unknown operating conditions by introducing an adaptive stability control strategy. Addressing the characteristics of DC distribution system parameters being prone to drift or varying operating conditions, this invention integrates a feature extraction mechanism based on an improved second-order generalized integrator frequency-locked loop (ISOGI-FLL), which can identify the resonant frequency and amplitude in the bus voltage in real time and accurately. Based on this, the DC active damper can dynamically optimize and lock the center frequency of the bandpass virtual impedance and adjust the damping gain in real time, thereby achieving adaptive absorption of resonant energy. This mechanism allows the DC active damper to spontaneously suppress system instability without prior acquisition of global system parameters, significantly improving the adaptive adjustment performance of the device in multi-node DC distribution network systems.

[0083] (2) This invention effectively eliminates the port impedance offset caused by the underlying control coupling by designing an impedance compensation stage, thus achieving accurate simulation of the virtual impedance characteristics. This invention analyzes the mechanism by which the equivalent admittance of the port deviates from the ideal characteristics due to the frequency domain coupling between the underlying dual closed-loop control architecture of the DC active damper and the bandpass virtual impedance control. By introducing an impedance compensation feedforward link based on the frequency band division principle, the complex high-order compensation stage is simplified in engineering, equivalent to a pure proportional constant related to the sampling coefficient, thereby completely offsetting the amplitude attenuation and phase deflection caused by the control loop. This invention ensures that the active damper can strictly present the required damping characteristics in the target resonant frequency band without significantly increasing the computational burden, thus guaranteeing the accuracy of resonance suppression.

[0084] (3) This invention proposes a parameter design method that takes into account both system stability boundaries and physical hardware constraints, thereby improving the safe operation level of the device under extreme conditions. Addressing the hardware physical limitations imposed on the active damper during damping action, this invention, combined with instantaneous power analysis, derives a capacitor parameter design criterion that meets the DC-side voltage regulation index. Simultaneously, for the filter inductor, this invention comprehensively considers the high-frequency switching ripple suppression requirements and the high-frequency dynamic tracking limit, establishing its physical value range. This systematic design method provides the necessary physical margin for the device when facing sudden load changes or severe transient resonance, effectively reducing the failure risk of power device overcurrent or capacitor overvoltage, and enhancing the reliability of the device in engineering applications. Attached Figure Description

[0085] To make the objectives, technical solutions, and advantages of the invention clearer, the invention will now be described in further detail with reference to the accompanying drawings, wherein:

[0086] Figure 1 This is a topology diagram of a multi-converter DC power distribution system with DC active dampers connected.

[0087] Figure 2 This is a topology and control block diagram of a DC active damper.

[0088] Figure 3 This is a block diagram of the small-signal transfer function of a DC active damper.

[0089] Figure 4 Y before and after adding the compensation stage in (s) Bode plot: (a) Y without addition in_v (s); (b) represents Y after addition. in_v (s).

[0090] Figure 5 The example is a four-node DC power distribution system.

[0091] Figure 6The simulation diagram shows the dynamic response of the system under load after the addition of a DC active damper.

[0092] Figure 7 Simulation diagram of the internal dynamic process of an adaptive active damper.

[0093] Figure 8 It serves as an experimental platform for DC power distribution systems and DC active dampers.

[0094] Figure 9 The steady-state experimental waveforms of the system are as follows: (a) is light load condition 1; (b) is heavy load condition 2.

[0095] Figure 10 The dynamic experimental waveforms for switching between operating conditions are as follows: (a) switching from operating condition 1 to operating condition 2; (b) switching from operating condition 2 to operating condition 1.

[0096] Figure 11 The dynamic experimental waveforms after the DC active damper control intervention are shown: (a) is the adaptive virtual impedance gain; (b) is the fixed virtual impedance gain. =0.1.

[0097] Figure 12 The experimental waveforms of the DC active damper are as follows: (a) is the control input waveform; (b) is the steady-state operating waveform. Detailed Implementation

[0098] 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, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but only to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0099] The following detailed explanation illustrates the specific implementation methods:

[0100] Example:

[0101] This embodiment discloses a plug-and-play DC active damper based on adaptive stability control.

[0102] A plug-and-play DC active damper based on adaptive stability control, such as Figure 1As shown, the DC active damper is connected in parallel at a node of the DC distribution network system and includes a main circuit and a control system.

[0103] The main circuit adopts a bidirectional DC-DC converter topology, including a (grid-side) filter inductor, a half-bridge arm composed of a first power switch and a second power switch, and a DC-side support capacitor. One end of the filter inductor is connected to the positive terminal of the DC distribution network system bus, and the other end is connected between the first power switch and the second power switch. The other end of the first power switch, which is not connected to the filter inductor, is connected to the negative terminal of the DC distribution network system bus and the negative terminal of the DC-side support capacitor. The other end of the second power switch, which is not connected to the filter inductor, is connected to the positive terminal of the DC-side support capacitor.

[0104] The core function of a DC active damper is to extract the AC disturbance component from the voltage or current of the distribution network as a control input, and simulate it as an equivalent virtual impedance connected in parallel at the node through closed-loop control, thereby increasing the system damping. The operating mode of an active damper is typically bidirectional: when the system resonates, it absorbs the high-frequency resonant energy in the network to suppress oscillations; simultaneously, to maintain the DC capacitor voltage v at its output terminal... a To ensure stability, the converter will feed excess energy back into the DC grid under the action of the voltage regulation loop.

[0105] like Figure 2 As shown, the control system adopts a dual closed-loop control architecture with an outer voltage loop and an inner inductor current loop, and integrates an adaptive active damping control module.

[0106] The outer voltage loop is used to acquire the voltage of the DC-side supporting capacitor and compare its feedback signal with the set voltage reference. The error value is processed by the voltage regulator and output as the base current setpoint.

[0107] The adaptive active damping control module is used to extract the AC disturbance component of the bus voltage in a DC distribution network system online and generate a high-frequency resonant compensation current setpoint through parallel virtual impedance control. Specifically, it is implemented based on ISOGI-FLL adaptive active damping control, which uses the online extraction of the resonant characteristic value by ISOGI-FLL to enable the parallel virtual impedance control G... vir (s) generates a portion of the current setpoint for the current loop.

[0108] The inner loop of the inductor current adds the base current setpoint to the high-frequency resonant compensation current setpoint as the total current setpoint of the grid-connected current loop. The total current setpoint is compared with the sampled grid-side filter inductor current feedback value. The error value is processed by the current regulator and pulse width modulation stage to generate the control signal to drive the first power switch and the second power switch.

[0109] The main reasons for adopting this control architecture in this invention are as follows:

[0110] (1) Frequency domain decoupling requirement of the control target: The output of the DC active damper is not connected to the actual load, but is only composed of DC support capacitor. Its control system faces two objectives: one is to maintain the DC side capacitor voltage v under steady state. a The system employs two key principles: first, it maintains a constant voltage level to ensure the damper has the physical margin to absorb and release energy; second, it accurately simulates the equivalent virtual impedance to inject or absorb high-frequency resonant current into the power grid. If a single voltage loop is used, the low-frequency steady-state voltage regulation and high-frequency dynamic damping commands will couple in the frequency domain, resulting in poor system disturbance rejection and instability. By introducing an inner current loop, the outer loop focuses on low-frequency voltage maintenance, while the inner loop focuses on high-frequency current tracking, effectively decoupling the control objectives.

[0111] (2) Wideband tracking capability of high-frequency resonant current: The core mechanism of active dampers is to counteract the resonant energy of the system by injecting specific high-frequency compensation current into the critical instability node. The control bandwidth of the inner current loop is usually much higher than that of the outer voltage loop, which can quickly and accurately track the virtual impedance current command in the mid-to-high frequency range, thereby effectively improving the dynamic response of the system and ensuring the effect of resonance suppression.

[0112] Compared with existing technologies, the beneficial effects of this invention are:

[0113] (1) This invention significantly improves the resonance suppression capability and robustness of DC active dampers under complex and unknown operating conditions by introducing an adaptive stability control strategy. Addressing the characteristics of DC distribution system parameters being prone to drift or varying operating conditions, this invention integrates a feature extraction mechanism based on an improved second-order generalized integrator frequency-locked loop (ISOGI-FLL), which can identify the resonant frequency and amplitude in the bus voltage in real time and accurately. Based on this, the DC active damper can dynamically optimize and lock the center frequency of the bandpass virtual impedance and adjust the damping gain in real time, thereby achieving adaptive absorption of resonant energy. This mechanism allows the DC active damper to spontaneously suppress system instability without prior acquisition of global system parameters, significantly improving the adaptive adjustment performance of the device in multi-node DC distribution network systems.

[0114] (2) This invention effectively eliminates the port impedance offset caused by the underlying control coupling by designing an impedance compensation stage, thus achieving accurate simulation of the virtual impedance characteristics. This invention analyzes the mechanism by which the equivalent admittance of the port deviates from the ideal characteristics due to the frequency domain coupling between the underlying dual closed-loop control architecture of the DC active damper and the bandpass virtual impedance control. By introducing an impedance compensation feedforward link based on the frequency band division principle, the complex high-order compensation stage is simplified in engineering, equivalent to a pure proportional constant related to the sampling coefficient, thereby completely offsetting the amplitude attenuation and phase deflection caused by the control loop. This invention ensures that the active damper can strictly present the required damping characteristics in the target resonant frequency band without significantly increasing the computational burden, thus guaranteeing the accuracy of resonance suppression.

[0115] (3) This invention proposes a parameter design method that takes into account both system stability boundaries and physical hardware constraints, thereby improving the safe operation level of the device under extreme conditions. Addressing the hardware physical limitations imposed on the active damper during damping action, this invention, combined with instantaneous power analysis, derives a capacitor parameter design criterion that meets the DC-side voltage regulation index. Simultaneously, for the filter inductor, this invention comprehensively considers the high-frequency switching ripple suppression requirements and the high-frequency dynamic tracking limit, establishing its physical value range. This systematic design method provides the necessary physical margin for the device when facing sudden load changes or severe transient resonance, effectively reducing the failure risk of power device overcurrent or capacitor overvoltage, and enhancing the reliability of the device in engineering applications.

[0116] To better illustrate the technical solution of the present invention, this embodiment will be described in more detail through the following parts.

[0117] I. Voltage outer loop

[0118] In the specific implementation process, the steps for processing the voltage outer loop include:

[0119] S11: Collect the DC-side support capacitor voltage and calculate the corresponding feedback signal;

[0120] S12: Compare the feedback signal of the DC-side support capacitor voltage with the set voltage reference and calculate the voltage error value;

[0121] S13: Input the voltage error value into the voltage regulator for processing, and then output the base current setpoint.

[0122] II. Adaptive Active Damping Control Module

[0123] In specific implementation, the processing steps of the adaptive active damping control module include:

[0124] S21: Collect the bus voltage of the DC distribution network system and calculate the corresponding feedback signal;

[0125] S22: The resonant angular frequency is extracted by deconstructing the feedback signal of the DC distribution network system bus voltage through the resonant feature extraction unit. Harmonic amplitude ;

[0126] S23: Based on the resonant angular frequency through the virtual impedance generation unit. Real-time locking of the center frequency of the virtual impedance The parameter adjuster is used according to the resonance amplitude. Dynamic calculation of damping gain and center frequency and damping gain Input bandpass virtual impedance transfer function Generate high-frequency resonant compensation current setpoint .

[0127] The adaptive active damping control module, as the core functional unit, comprises three parts: resonance feature extraction, adaptive adjustment of control parameters, and generation of compensation current. Its specific implementation logic is as follows:

[0128] Real-time extraction of resonance characteristics: This module takes the acquired DC distribution network bus voltage as input and first performs feature deconstruction through an internally integrated improved second-order generalized integrator frequency-locked loop (ISOGI-FLL). To address the interference of DC voltage bias on small-signal extraction, the module incorporates a DC estimation loop based on gradient descent, which can strip the DC component from the voltage signal in real time, thereby obtaining a clean AC disturbance component. Furthermore, considering the abrupt changes during system startup or operating condition switching, the feature extraction unit introduces a nonlinear damping term as a soft-start constraint. By dynamically adjusting the gain of the frequency estimation loop, it effectively suppresses frequency spurious fluctuations during transient processes, ensuring the resonant angular frequency. With resonance amplitude The smoothness and accuracy of the extraction.

[0129] Adaptive adjustment of control parameters: After acquiring the resonance characteristics, the module enters the parameter mapping and optimization stage. Resonant angular frequency. After standardization, it is directly mapped to the center frequency f of the bandpass virtual impedance controller. c This allows the frequency selectivity of the damper to automatically align with the system's true resonant point. Simultaneously, the resonant amplitude V... ac The error input is fed into the gain regulator, and the gain coefficient k of the virtual impedance is dynamically adjusted using a proportional-integral control algorithm. r This closed-loop control logic aims to automatically match the optimal damping force based on the real-time changes in resonance intensity until the oscillation component of the bus voltage decays to a preset threshold range, thus achieving adaptive adjustment of control parameters.

[0130] Generation of the compensation current: The virtual impedance generation unit is based on the f obtained from the above optimization. c With k r Through the second-order bandpass transfer function G vir (s) Generate the high-frequency resonant compensation current setpoint i h,ref To ensure that the instruction does not undergo frequency domain distortion during execution through the underlying dual closed-loop circuit, the signal first passes through the aforementioned impedance compensation stage G. ca (s) Perform pre-correction. Corrected compensation instruction i h,ref With respect to the base current setpoint i of the voltage outer loop output a,ref The total inductor current setpoint, obtained by linear superposition at the aggregation node, is directly fed into the inner loop of the inductor current for high-speed tracking control. Through this signal flow, the high-level decisions of the adaptive control algorithm are transformed into the PWM action of the switching transistor, ultimately achieving precise absorption and suppression of the target resonant energy at the device port.

[0131] 1. Resonance Feature Extraction Unit

[0132] The resonance feature extraction unit is an improved second-order generalized integrator frequency-locked loop (ISOGI-FLL). Specific features include: 1) DC suppression loop: A DC estimation loop based on gradient descent is introduced into the standard SOGI-QSG structure, with its integral update expression being... 1) To eliminate the influence of DC bias in the bus voltage on frequency estimation; 2) Soft-start circuit: Introduce a nonlinear damping term into the frequency estimator. 3) Frequency locking logic: By monitoring the dynamic angular frequency, the evolution process of state variables is modified to suppress frequency spurious fluctuations caused by sudden changes in system startup or operating conditions; The convergence state is determined, and the output value is locked when the preset tolerance conditions are met, ensuring that the damping control is accurately applied to the true resonant point.

[0133] The resonant angular frequency is output based on the feedback signal of the DC distribution network system bus voltage through an improved second-order generalized integrator frequency-locked loop. Simultaneously, the AC disturbance component of the DC distribution network system bus voltage is separated and extracted from the voltage feedback signal, and the resonant amplitude of the AC disturbance component is extracted. ;

[0134] Improvements to the frequency-locked loop of the improved second-order generalized integrator include:

[0135] (1) By introducing a DC suppression loop based on gradient descent method, the DC bias in the feedback signal of the bus voltage of the DC distribution network system is eliminated;

[0136] definition The cost function of the DC distribution network system is used to estimate the DC component. Revised to:

[0137] ;

[0138] By applying gradient descent to minimize the cost function, the integral update expression for the DC component estimate is obtained as follows:

[0139] ;

[0140] In the formula: This is an error signal; The feedback signal includes the resonant disturbance; for The estimated value of the AC disturbance component at the shaft output terminal, i.e., the AC disturbance component; This is the gain constant of the DC suppression loop;

[0141] (2) The expression for the estimation of the resonant angular frequency is modified into the following nonlinear expression through a soft-start mechanism:

[0142] ;

[0143] In the formula: The derivative of the resonant angular frequency; This is the gain coefficient; This is an estimate of the amplitude of the AC disturbance component; For design constants; This is an error signal; This is the voltage estimate at the quadrature axis output terminal;

[0144] (3) A convergence determination logic based on exponential moving average filtering is adopted to continuously monitor the resonant angular frequency of the frequency-locked loop output of the improved second-order generalized integrator, and lock it to the final resonant angular frequency when the resonant angular frequency converges:

[0145] (3.1) Introduce an exponential moving average filter to measure the resonant angular frequency of the real-time output. Smoothing is performed to obtain the smoothed frequency. ;

[0146] The discrete update expression for the exponential moving average filter is:

[0147] ;

[0148] In the formula: This represents the current discrete sampling time. This refers to the previous sampling time. These are the filtering smoothing coefficients, and ;

[0149] (3.2) Calculate the current resonant angular frequency in real time With smooth frequency absolute difference ;

[0150] (3.3) If the absolute difference continuous The values ​​are all less than the preset tolerance threshold within each calculation cycle. If the resonant angular frequency has converged, then the resonant angular frequency value at this moment is locked as the final resonant angular frequency. .

[0151] 2. Virtual impedance generation unit

[0152] The processing steps of the virtual impedance generation unit include:

[0153] S241: Regarding the resonant angular frequency After standardization, it is directly mapped to the center frequency of the bandpass virtual impedance. ;

[0154] S242: Adjust the resonant amplitude The error input is fed into the gain regulator, and the gain coefficient of the virtual impedance is dynamically adjusted using a proportional-integral control algorithm. ;

[0155] S243: Center frequency and damping gain Input bandpass virtual impedance transfer function Reconstruct the virtual impedance;

[0156] The formula is expressed as:

[0157] ;

[0158] In the formula: For reconstructed virtual impedance; This represents the bandwidth corresponding to the virtual impedance at the -3dB cutoff frequency. Indicates damping gain; Indicates the center frequency;

[0159] S244: Generate high-frequency resonant compensation current setpoint based on reconstructed virtual impedance.

[0160] III. Inductor Current Inner Loop

[0161] In the specific implementation process, the processing steps for the inner loop of inductor current include:

[0162] S31: Acquire the filter inductor current and calculate the corresponding feedback signal;

[0163] S32: Add the base current setpoint to the high-frequency resonant compensation current setpoint to obtain the total current setpoint of the grid-connected current loop;

[0164] S33: Compare the total current setpoint with the feedback signal of the filter inductor current and calculate the current error value;

[0165] S34: After the current error value is input into the current regulator and pulse width modulation stage for processing, a control signal is generated to drive the first power switch and the second power switch.

[0166] Specifically, the bandwidth design of the control system follows the principles of frequency domain decoupling and dynamic tracking. The control bandwidth of the inner loop of the inductor current is set to 1 / 10 to 1 / 5 of the switching frequency of the first and second power switches to ensure that the active damper can quickly and accurately track the given value of the high-frequency resonant compensation current. The control bandwidth of the outer loop of the voltage is much lower than that of the inner loop of the inductor current, which is used to maintain the steady-state constant voltage of the DC-side support capacitor without interfering with the high-frequency damping command.

[0167] IV. Impedance Modeling and Compensation Design of Active Dampers

[0168] 1. Impedance Modeling of Active Dampers

[0169] To accurately evaluate the dynamic interaction characteristics of an active damper after it is connected to the grid, it is necessary to derive the equivalent parallel admittance Y at its grid-side port based on its dual closed-loop control architecture and main circuit topology. ad That is, the input admittance Y of the active damper in .

[0170] like Figure 3 As shown, a small-signal disturbance model of the active damper is established. Considering that the output of the active damper consists only of a voltage-stabilizing capacitor and does not undertake actual DC steady-state active power transmission, its equivalent DC load resistance can be regarded as infinite in the model. The parameters of each open-loop two-port network can be derived. The port equivalent admittance of the active damper is obtained by derivation, as shown in equation (1):

[0171] (1)

[0172] Due to the closed-loop input admittance Y under the voltage and current dual closed-loop system in_c (s) is shown in the following formula:

[0173] (2)

[0174] in The open-loop gain of the voltage outer loop is shown in equation (3):

[0175] (3)

[0176] Combining equations (1) and (2), we can obtain:

[0177] (4)

[0178] In the formula: The input voltage sampling feedback coefficient, Let be the closed-loop transfer function of the inductor current. The transfer function of the impedance compensation stage. For an ideal bandpass virtual impedance transfer function, This refers to the open-loop gain of the outer voltage loop; The input admittance transfer function under current closed-loop conditions; The input-output voltage transfer function under current closed-loop conditions; The transfer function from the inductor current to the output voltage; This is the voltage feedback coefficient; It is a voltage loop PI regulator.

[0179] The above analytical expression clearly reveals the essential port characteristics of the DC active damper: its final external admittance Y in_a (s) consists of two parts connected in parallel. The first term is the basic admittance determined by the dual closed-loop control; the second term is the additional admittance generated by virtual impedance control.

[0180] Because this additional admittance includes the closed-loop gain of the control system, such as G. ic (s) and T v (s), which means that the virtual impedance control element G vir (s) The system is affected by the coupling effect of the bandwidth of the underlying control loop, therefore an impedance compensation stage G is required. ca (s).

[0181] 2.2 Design of Impedance Compensation Circuit for Active Dampers

[0182] To achieve precise suppression of specific high-frequency resonances while avoiding impact on the steady-state power flow of the DC distribution network system, an ideal virtual admittance control command G is required. vir (s) It should possess frequency selectivity similar to a bandpass filter. Combining the aforementioned oscillation component characteristics extracted based on ISOGI, the ideal frequency-selective virtual admittance transfer function can be expressed as:

[0183] (5)

[0184] According to equation (4), without compensation, the additional virtual admittance actually presented at the active damper port is:

[0185] (6)

[0186] Therefore, without the introduction of the aforementioned impedance compensation stage Previously, affected by the above and Due to the influence of dynamic characteristics, the actual additional virtual admittance experiences amplitude attenuation and phase shift in the resonant frequency band.

[0187] After substituting the actual physical and control parameters, such as Figure 4 As shown in (a), the Bode plot comparison clearly reveals the huge deviation between the actual and ideal characteristics. Due to the voltage loop gain T v (s) and inductor current referenced to input current transfer function G ic (s) Due to the existence of dynamic characteristics, the actual virtual admittance shows a significant amplitude attenuation at the resonant frequency, which weakens the active damping capability of the active damper.

[0188] To eliminate the frequency domain offset phenomenon, an impedance compensation circuit is inserted into the output feedforward path of the adaptive active damping control module. The design goal of the compensation stage is to completely offset the coupling terms introduced by the underlying control loop; therefore, the ideal compensation function should be the reciprocal of the coupling terms.

[0189] (7)

[0190] By decomposing equation (7), we can obtain:

[0191] (8)

[0192] The impedance compensation stage Engineering design is simplified based on frequency band allocation principles, specifically including:

[0193] 1) Low-frequency simplification based on voltage loop bandwidth decoupling. The outer voltage loop of the active damper is mainly used to maintain the steady-state constant voltage of the DC support capacitor. Its cutoff frequency is usually designed to be low, typically much lower than the bandwidth of the grid-side inductor current loop and the potential resonant frequency of the system. Therefore, when analyzing the mid-to-high frequency resonant band, the capacitor voltage fluctuation can be approximated as minimal, and the voltage loop gain T... v The effect of (s) in the resonant frequency band is negligible. At this point, considering the current closed-loop transfer function G... ic The internal structure of (s) and the compensation process can be simplified as follows:

[0194] (9)

[0195] In the formula, and These are the transfer functions of duty cycle with respect to inductor current and input current, respectively. Since the input current in a Boost converter is the same as the inductor current, ... The two can be directly simplified.

[0196] 2) Gain approximation based on the high-frequency characteristics of the current loop. To ensure that the active damper can quickly track AC disturbance components, the cutoff frequency of its inner inductor current loop is usually designed to be relatively high (e.g., 1 / 10 of the switching frequency, i.e., f). c =5kHz). Within the main resonant frequency range, the open-loop current gain amplitude is sufficiently large (i.e., ), can be approximated as .

[0197] After the above two steps of order reduction and simplification, the originally complex high-order compensation process is greatly simplified into a pure proportionality constant related to the sampling coefficients:

[0198] (10)

[0199] In the formula: The current sampling feedback coefficient of the filter inductor is... For the bus voltage sampling feedback coefficient of the DC distribution network system;

[0200] The simplified constant gain compensation circuit G ca (s) After embedding the control system, redraw the Bode plot of the virtual admittance, such as Figure 4 As shown in (b). A comparison reveals that, after compensation, within the target resonant frequency band, the amplitude-frequency and phase-frequency characteristics of the actual virtual admittance are similar to those of the ideal G. vir (s) Maintain good consistency.

[0201] V. Parameter Design of Active Dampers

[0202] The apparent power capacity of the filter inductor, DC-side support capacitor, and active damper in the main circuit are designed with consideration for both high-frequency dynamic tracking limits and physical hardware constraints. Specifically, this includes:

[0203] 1) Design of active damper capacity and energy storage capacitor voltage:

[0204] The core function of an active damper is to simulate a virtual admittance connected in parallel at critical nodes in the target resonant frequency range to absorb resonant energy in the network. Since it does not respond to the DC base power of the DC distribution network system, its capacity depends entirely on the transient resonance suppression requirements of the system under harsh operating conditions.

[0205] In multi-node DC systems, to ensure system stability, the equivalent virtual admittance provided by the active damper must be greater than the critical minimum value G required to maintain global system stability. v_minConsidering that during large disturbance transients such as load changes and network topology reconfiguration, the oscillation components at critical nodes may surge in a short period of time, the capacity design of active dampers must have sufficient margin to prevent overcurrent saturation and failure during transient processes.

[0206] Based on this, the minimum apparent power capacity S of the active damper can be estimated. AD_min It should be no less than:

[0207] (11)

[0208] In the formula: This refers to the rated DC bus voltage of the DC distribution network system. The maximum expected range of the ratio of the target resonant voltage component to the rated DC voltage is typically taken as... G v_min To ensure that the current multi-node system meets the minimum equivalent virtual admittance threshold required by the global stability criterion.

[0209] To ensure the device maintains linear controllability of the inner current loop during bidirectional operation, i.e., to guarantee the Boost converter is always in boost mode, the steady-state voltage setpoint V of the DC-side support capacitor is set to... a It must be strictly greater than the maximum transient bus voltage at the node. Typically, it is taken as:

[0210] (12)

[0211] 2) DC-side support capacitor design:

[0212] Based on the limitation of voltage fluctuation caused by a single charge and discharge cycle of the capacitor due to resonant energy pulsation, a lower limit value is set for the DC-side supporting capacitor. for:

[0213]

[0214] In the formula: This is the steady-state bus voltage. The amplitude of the high-frequency resonant current absorbed by the active damper. The lowest angular frequency in the system's target resonant frequency band. The allowable peak-to-peak value of capacitor voltage ripple;

[0215] 3) Filter inductor design:

[0216] To simultaneously meet the requirements for suppressing high-frequency switching ripple and achieving zero steady-state error tracking of high-frequency resonant current, the filter inductor is configured... The range of values ​​is The upper and lower limits are respectively:

[0217]

[0218]

[0219] In the formula: For switching frequency, The maximum permissible high-frequency switching current ripple limit. This is the highest angular frequency in the system's target resonant frequency band.

[0220] VI. Experimental Instructions

[0221] To better illustrate the advantages of the technical solution of the present invention, the following experiment is disclosed in this embodiment.

[0222] Firstly, regarding simulation verification, this embodiment constructs as follows: Figure 5 The model of a four-node low-voltage DC power distribution system is shown in Table 1. The system parameters are shown in Table 2, and the active damper parameters are shown in Table 2.

[0223] Table 1 Parameters of DC Power Distribution System

[0224]

[0225] Table 2 Parameters of Active Dampers

[0226]

[0227] The system is set with two operating conditions: Condition 1: R4 = 6Ω, and Condition 2: R4 = 2Ω. Under Condition 1, the system is in a stable state, while under Condition 2, the system is in an unstable state, and the bus voltage oscillates.

[0228] In the simulation verification of the system's dynamic response and power characteristics, when the system experiences a sudden load shedding disturbance at 0.5s, the system's response process is as follows: Figure 6 As shown. Due to severe impedance mismatch, the system momentarily becomes unstable and triggers global oscillation. At this point, the active damper quickly detects the bus voltage ripple exceeding the limit and activates adaptive control.

[0229] Figure 7 The device-level key state variables during the stabilization process are shown in detail. The internal ISOGI-FLL module accurately finds the frequency to 314Hz, then assigns this frequency to the center frequency of the virtual impedance, and enables adaptive gain adjustment to make the voltage of each node converge smoothly to a steady state.

[0230] To verify the feasibility of the proposed strategy in a real physical system, this embodiment constructs a system as follows: Figure 8 The hardware experimental platform shown includes four Buck converter modules and one independent active damper.

[0231] With the same system parameters as described above, the experiment was conducted under two operating conditions: Condition 1 was a steady state with R4 = 6Ω, and Condition 2 was a disturbed state with R4 = 2Ω. Figure 9 (a) and Figure 9 (b) The two node voltages v under operating conditions 1 and 2 are respectively. node2 v node4 and the output current I of the two load converters o3 I o4 The waveforms show that, under operating condition 2, the bus voltage exhibits significant oscillations at a frequency of 312Hz, which is close to the theoretically predicted 317Hz. Figure 10 Dynamic experimental waveforms for switching between operating conditions are presented.

[0232] In this unstable state, comparative experiments were conducted using different control strategies, as follows: Figure 11 As shown, where Figure 11 (a) When using the adaptive virtual impedance control proposed in this invention, the system can effectively suppress oscillations within 20ms; in contrast, using... Figure 11 (b) As shown in the traditional fixed-gain control, the system requires approximately 40ms to recover stability. This comparison objectively demonstrates that the method of this invention has a faster dynamic response speed and higher robustness. Finally, the port experimental waveform of the active damper is as follows: Figure 12 As shown, during the steady-state operation of the system, the average value of its input current approaches zero, further confirming that the device has minimal steady-state energy loss to the DC power distribution system.

[0233] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit the technical solutions. Those skilled in the art should understand that any modifications or equivalent substitutions to the technical solutions of the present invention without departing from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A plug-and-play DC active damper based on adaptive stability control, characterized in that, The DC active damper is connected in parallel at a node of the DC distribution network system and includes a main circuit and a control system. The main circuit adopts a bidirectional DC-DC converter topology, including a filter inductor, a half-bridge arm composed of a first power switch and a second power switch, and a DC-side support capacitor. One end of the filter inductor is connected to the positive terminal of the DC distribution network system bus, and the other end is connected between the first power switch and the second power switch. The other end of the first power switch, which is not connected to the filter inductor, is connected to the negative terminal of the DC distribution network system bus and the negative terminal of the DC-side support capacitor. The other end of the second power switch, which is not connected to the filter inductor, is connected to the positive terminal of the DC-side support capacitor. The control system adopts a dual closed-loop control architecture with an outer voltage loop and an inner inductor current loop, and integrates an adaptive active damping control module. The outer voltage loop is used to generate the base current setpoint through the voltage of the DC-side supporting capacitor; The adaptive active damping control module is used to extract the AC disturbance component of the bus voltage of the DC distribution network system online, and generate the high-frequency resonant compensation current setpoint through parallel virtual impedance control; The inner loop of the inductor current is used to generate control signals to drive the first power switch and the second power switch by filtering the inductor current, the base current setpoint, and the high-frequency resonant compensation current setpoint.

2. The plug-and-play DC active damper based on adaptive stability control as described in claim 1, characterized in that: The steps for processing the voltage outer loop include: S11: Collect the DC-side support capacitor voltage and calculate the corresponding feedback signal; S12: Compare the feedback signal of the DC-side support capacitor voltage with the set voltage reference and calculate the voltage error value; S13: Input the voltage error value into the voltage regulator for processing, and then output the base current setpoint.

3. The plug-and-play DC active damper based on adaptive stability control as described in claim 2, characterized in that: The processing steps of the adaptive active damping control module include: S21: Collect the bus voltage of the DC distribution network system and calculate the corresponding feedback signal; S22: The resonant angular frequency is extracted by deconstructing the feedback signal of the DC distribution network system bus voltage through the resonant feature extraction unit. Harmonic amplitude ; S23: Based on the resonant angular frequency Real-time locking of the center frequency of the virtual impedance The parameter adjuster is used according to the resonance amplitude. Dynamic calculation of damping gain Finally, the center frequency and damping gain The input bandpass virtual impedance transfer function generates the high-frequency resonant compensation current setpoint.

4. The plug-and-play DC active damper based on adaptive stability control as described in claim 3, characterized in that: In step S22, the resonant feature extraction unit is an improved second-order generalized integrator frequency-locked loop; the improved second-order generalized integrator frequency-locked loop outputs the resonant angular frequency based on the feedback signal of the DC distribution network system bus voltage. Simultaneously, the AC disturbance component of the DC distribution network system bus voltage is separated and extracted from the voltage feedback signal, and the resonant amplitude of the AC disturbance component is extracted. ; Improvements to the frequency-locked loop of the improved second-order generalized integrator include: (1) By introducing a DC suppression loop based on gradient descent method, the DC bias in the feedback signal of the bus voltage of the DC distribution network system is eliminated; definition The cost function of the DC distribution network system is used to estimate the DC component. Revised to: ； By applying gradient descent to minimize the cost function, the integral update expression for the DC component estimate is obtained as follows: ； In the formula: This is an error signal; The feedback signal includes the resonant disturbance; for The estimated value of the AC disturbance component at the shaft output terminal, i.e., the AC disturbance component; This is the gain constant of the DC suppression loop; (2) The expression for the estimation of the resonant angular frequency is modified into the following nonlinear expression through a soft-start mechanism: ； In the formula: The derivative of the resonant angular frequency; This is the gain coefficient; This is an estimate of the amplitude of the AC disturbance component; For design constants; This is an error signal; This is the voltage estimate at the quadrature axis output terminal; (3) A convergence determination logic based on exponential moving average filtering is adopted to continuously monitor the resonant angular frequency of the frequency-locked loop output of the improved second-order generalized integrator, and lock it to the final resonant angular frequency when the resonant angular frequency converges: (3.1) Introduce an exponential moving average filter to measure the resonant angular frequency of the real-time output. Smoothing is performed to obtain the smoothed frequency. ; The discrete update expression for the exponential moving average filter is: ； In the formula: This represents the current discrete sampling time. This refers to the previous sampling time. These are the filtering smoothing coefficients, and ; (3.2) Calculate the current resonant angular frequency in real time With smooth frequency absolute difference ; (3.3) If the absolute difference continuous The values ​​are all less than the preset tolerance threshold within each calculation cycle. If the resonant angular frequency has converged, then the resonant angular frequency value at this moment is locked as the final resonant angular frequency. .

5. The plug-and-play DC active damper based on adaptive stability control as described in claim 3, characterized in that: In step S24, the processing steps of the virtual impedance generation unit include: S241: Regarding the resonant angular frequency After standardization, it is directly mapped to the center frequency of the bandpass virtual impedance. ; S242: Adjust the resonant amplitude The error input is fed into the gain regulator, and the gain coefficient of the virtual impedance is dynamically adjusted using a proportional-integral control algorithm. ; S243: Center frequency and damping gain Input bandpass virtual impedance transfer function Reconstruct the virtual impedance; The formula is expressed as: ； In the formula: For reconstructed virtual impedance; This represents the bandwidth corresponding to the virtual impedance at the -3dB cutoff frequency. Indicates damping gain; Indicates the center frequency; S244: Generate high-frequency resonant compensation current setpoint based on reconstructed virtual impedance.

6. The plug-and-play DC active damper based on adaptive stability control as described in claim 1, characterized in that: The transfer function of an impedance compensation stage is inserted in series into the output feedforward path of the adaptive active damping control module. Pre-correction is performed on the setpoint of the high-frequency resonant compensation current; Impedance compensation element transfer function Engineering design is simplified based on frequency band allocation principles, specifically including: (1) Simplification of low frequency band: In the mid-to-high frequency resonant frequency band, the influence of the voltage outer loop with a lower cutoff frequency is ignored, and it is approximately assumed that , This represents the open-loop gain of the outer voltage loop. (2) High-frequency band simplification: In the resonant frequency band within the cutoff frequency of the inner loop of the inductor current, the amplitude of the open-loop current gain is much greater than 1. It is approximately assumed that the transfer coefficient change caused by the state feedback term of the inner loop of the current tends to the ideal tracking state. (3) Through simplification in the low-frequency band and simplification in the high-frequency band, the transfer function of the impedance compensation stage is... Equivalent to a pure scaling constant related to the hardware sampling coefficients: ； In the formula: The current sampling feedback coefficient of the filter inductor; This represents the bus voltage sampling feedback coefficient of the DC distribution network system.

7. The plug-and-play DC active damper based on adaptive stability control as described in claim 1, characterized in that: The processing steps for the inner loop of inductor current include: S31: Acquire the filter inductor current and calculate the corresponding feedback signal; S32: Add the base current setpoint to the high-frequency resonant compensation current setpoint to obtain the total current setpoint of the inner loop of the inductor current. S33: Compare the total current setpoint with the feedback signal of the filter inductor current and calculate the current error value; S34: After the current error value is input into the current regulator and pulse width modulation stage for processing, a control signal is generated to drive the first power switch and the second power switch.

8. The plug-and-play DC active damper based on adaptive stability control as described in claim 7, characterized in that: The bandwidth design of the control system follows the principles of frequency domain decoupling and dynamic tracking. The control bandwidth of the inner loop of the inductor current is set to 1 / 10 to 1 / 5 of the switching frequency of the first and second power switches. The control bandwidth of the outer loop of the voltage is lower than that of the inner loop of the inductor current.

9. The plug-and-play DC active damper based on adaptive stability control as described in claim 8, characterized in that: The port equivalent admittance of a DC active damper is modeled as follows: ； ； ； In the formula: The port equivalent admittance of the DC active damper; The basic admittance determined by the dual closed-loop control; The input voltage sampling feedback coefficient; This is the closed-loop transfer function for inductor current. The transfer function for the impedance compensation stage; This is a bandpass virtual impedance transfer function; This represents the open-loop gain of the outer voltage loop. The input admittance transfer function under current closed-loop conditions; The input-output voltage transfer function under current closed-loop conditions; The transfer function from the inductor current to the output voltage; This is the voltage feedback coefficient; It is a voltage loop PI regulator.

10. The plug-and-play DC active damper based on adaptive stability control as described in claim 1, characterized in that: The parameter design of DC active dampers includes: (1) Design of DC active damper capacity and energy storage capacitor voltage: Set the steady-state voltage setpoint of the DC-side support capacitor. Greater than the maximum transient bus voltage at the node, satisfying , This refers to the rated bus voltage of the DC distribution network system. Based on the minimum equivalent virtual admittance critical value required to maintain the global stability of the DC distribution network system Set the minimum apparent power capacity of the DC active damper. satisfy: ； In the formula: This refers to the rated bus voltage of the DC distribution network system. This represents the maximum expected range of the ratio of the target resonant voltage component to the rated DC voltage. (2) Design of DC-side supporting capacitor: Based on the limitation of voltage fluctuation caused by a single charge and discharge cycle of the capacitor due to resonant energy pulsation, a lower limit value is set for the DC-side supporting capacitor. for: ； In the formula: This is the steady-state bus voltage; The amplitude of the high-frequency resonant current absorbed by the DC active damper; The lowest angular frequency of the target resonant frequency band for the DC distribution network system; The allowable peak-to-peak value of capacitor voltage ripple; (3) Filter inductor design: Setting the filter inductor The range of values ​​is The upper and lower limits are respectively: ； ； In the formula: The switching frequency; The maximum permissible high-frequency switching current ripple limit; This is the highest angular frequency in the system's target resonant frequency band.

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