VSG deadbeat prediction control method based on impedance identification adaptive compensation

Abstract

The invention discloses a VSG deadbeat prediction control method based on impedance identification adaptive compensation, and the method comprises the following steps: collecting the grid-connected point voltage and current of a three-phase grid-connected converter, and converting the voltage and current into corresponding components in a rotating coordinate system; and identifying a power grid impedance parameter based on the component, calculating a system short-circuit ratio, comparing the system short-circuit ratio with a preset threshold value, and selecting a standard predictive control or impedance adaptive compensation mode. In a standard mode, a virtual synchronous generator discretization mathematical model considering system delay is constructed, and first control voltage is generated through dead-beat predictive current control; and in the compensation mode, self-adaptive compensation of a power grid impedance parameter is introduced on the basis of the first control voltage, a final control voltage is obtained, a PWM driving signal is generated according to the final control voltage, and grid-connected operation of the converter is controlled. According to the method, dead-beat predictive current control and a virtual synchronous generator technology are combined, a power grid impedance identification and self-adaptive compensation mechanism is added, and self-adaptive high-performance control of the converter under strong and weak power grid conditions is realized.

Description

Technical Field

[0001] This invention relates to a VSG deadbeat predictive control method based on impedance identification and adaptive compensation, belonging to the technical field of new energy grid connection and energy storage converter. Background Technology

[0002] With the continuous expansion of new energy power generation, the proportion of power electronic converters in power systems has increased significantly, leading to a decrease in the inertia and damping characteristics of the power grid and affecting system stability. Virtual synchronous generator (VSG) control strategies, by simulating the operating characteristics of synchronous generators, provide inertial support and damping for the system, and have become an effective means to improve the stability of new energy grid-connected systems.

[0003] However, in practical applications, grid-connected inverters often operate in weak grid environments with high grid impedance, which can easily lead to system model mismatch, decreased control performance, or even instability. Deadbeat predictive current control has advantages such as fast dynamic response, fixed switching frequency, and ease of digital implementation; however, its control accuracy is affected by changes in model parameters or the presence of measurement noise. Furthermore, traditional control methods lack adaptability to changes in grid impedance under weak grid conditions, making it difficult to guarantee system robustness.

[0004] To address this, various grid impedance identification methods and adaptive control strategies have been proposed in the existing technologies, but a systematic control architecture is still lacking that can adaptively switch control modes according to grid strength and achieve high-precision current tracking and system stability under weak grid conditions. Summary of the Invention

[0005] The purpose of this invention is to provide a deadbeat predictive control method for VSG based on impedance identification and adaptive compensation. This invention combines deadbeat predictive current control with virtual synchronous generator technology and introduces grid impedance identification and adaptive compensation mechanisms to achieve adaptive high-performance control of the grid-connected inverter under both strong and weak grid conditions, effectively improving the system's dynamic response, robustness, and grid-connected power quality.

[0006] The technical solution provided by this invention is as follows: a VSG deadbeat predictive control method based on impedance identification and adaptive compensation, comprising the following steps:

[0007] Step 1: Collect the voltage and current at the grid connection point of the three-phase grid-connected converter, and obtain the voltage and current components in the rotating coordinate system through coordinate transformation;

[0008] Step 2: Identify the grid impedance based on the voltage and current components to obtain the grid impedance parameters, and calculate the system short-circuit ratio based on the grid impedance parameters;

[0009] Step 3: Compare the short-circuit ratio with a preset threshold, and select to enter the standard predictive control mode or the impedance adaptive compensation mode based on the comparison result.

[0010] Step 4: Under the standard predictive control mode, construct a discretized mathematical model of a virtual synchronous generator that takes into account system delay, and perform deadbeat predictive current control based on the discretized mathematical model of the virtual synchronous generator to generate the first control voltage.

[0011] Step 5: In the impedance adaptive compensation mode, based on the first control voltage, an adaptive compensation based on the grid impedance parameters is introduced to generate the final control voltage.

[0012] Step 6: Generate a PWM drive signal based on the final control voltage to control the three-phase grid-connected converter to operate in grid-connected mode.

[0013] In the above-mentioned VSG deadbeat predictive control method based on impedance identification and adaptive compensation, step 2 involves the grid impedance identification using an active detection method, a passive detection method, or a combination of both. The active detection method includes injecting a disturbance signal of a specific frequency into the grid and analyzing the response. The passive detection method includes using inherent harmonics or natural fluctuations of the grid for parameter identification.

[0014] In the aforementioned VSG deadbeat predictive control method based on impedance identification and adaptive compensation, step 2, the formula for calculating the system short-circuit ratio is as follows:

[0015] ;

[0016] in, The effective value of the rated line voltage at the grid connection point. The magnitude of the grid impedance. This refers to the rated active power of the converter.

[0017] The aforementioned VSG deadbeat predictive control method based on impedance identification and adaptive compensation establishes the discretized mathematical model of the virtual synchronous generator in the following manner:

[0018] Establish a continuous-time state equation that includes the LCL filter and the grid impedance;

[0019] The continuous-time state equation is discretized using the forward Euler method, the backward Euler method, or the trapezoidal integral method to obtain a discretized mathematical model.

[0020] The aforementioned VSG deadbeat predictive control method based on impedance identification and adaptive compensation specifically includes the deadbeat predictive current control as follows:

[0021] Based on the discretized mathematical model, a deadbeat predictive control law is derived that enables the grid-connected current to track its reference value in the next control cycle.

[0022] The reference current and the sampled current are predicted and delayed to eliminate the digital delay of at least one control cycle, thereby generating the first control voltage.

[0023] In the aforementioned VSG deadbeat predictive control method based on impedance identification and adaptive compensation, step 5 involves the adaptive compensation being implemented by an adaptive controller. Specifically, the identified grid impedance parameters are substituted into the calculation equation of the control voltage, and the adaptive controller dynamically outputs a compensation voltage based on the tracking error of the grid current. The compensation voltage is then superimposed with the first control voltage to generate the final control voltage.

[0024] The aforementioned VSG deadbeat predictive control method based on impedance identification and adaptive compensation employs a model-based adaptive control strategy or a model-free adaptive optimization strategy in the adaptive controller.

[0025] The model-based adaptive control strategy is either model reference adaptive control or adaptive control based on Lyapunov stability theory.

[0026] The model-free adaptive optimization strategy is extreme value search control, fuzzy logic control, or neural network adaptive control.

[0027] A system for implementing the aforementioned VSG deadbeat predictive control method based on impedance identification and adaptive compensation includes:

[0028] The signal acquisition and coordinate transformation unit is used to acquire the voltage and current at the grid connection point of the three-phase grid-connected converter, and perform coordinate transformation to output the voltage and current components in the rotating coordinate system.

[0029] The power grid impedance identification and status determination unit has its input end connected to the output end of the signal acquisition and coordinate transformation unit. It is used to perform power grid impedance identification, calculate the short-circuit ratio and determine the power grid status, and output a mode selection signal.

[0030] The deadbeat prediction control unit has its input terminal connected to the output terminal of the signal acquisition and coordinate transformation unit and the output terminal of the virtual synchronous generator outer loop controller, respectively. It is used to receive the voltage component, current component and reference current command, and is activated in the standard predictive control mode to output the first control voltage.

[0031] An adaptive compensation unit, whose input terminal is connected to the output terminal signal of the power grid impedance identification and state determination unit, is used to receive the power grid impedance parameters and is activated in the impedance adaptive compensation mode to output the adaptive compensation amount.

[0032] The signal synthesis and PWM generation unit has its input terminals connected to the output terminals of the deadbeat prediction control unit and the adaptive compensation unit, respectively, and is used to synthesize the first control voltage and the adaptive compensation amount to generate the final control voltage.

[0033] An electronic device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, it implements the steps of the aforementioned method.

[0034] A computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the method described above.

[0035] Compared with the prior art, the present invention has the following significant advantages:

[0036] 1. This invention obtains dynamic parameters by identifying grid impedance in real time and introduces an adaptive compensation mechanism to actively counteract the interference of impedance changes on the control model, thereby solving the parameter mismatch problem at its root and ensuring that the system can still operate stably in a weak grid environment, significantly improving its ability to resist grid fluctuations.

[0037] 2. This invention combines the fast response advantage of deadbeat predictive control with the grid-friendly characteristics of virtual synchronous generators, and designs a compensation strategy to address the inherent delay of digital control systems. This not only accelerates the system's response speed to power commands and grid disturbances, but also significantly improves the tracking accuracy of grid-connected current, effectively suppresses current harmonics, reduces total harmonic distortion, and ensures that grid-connected power quality meets industry standards.

[0038] 3. This invention quantifies grid strength by calculating the short-circuit ratio and automatically switches control modes based on preset thresholds: standard predictive control is activated under strong grid conditions to prioritize dynamic performance; under weak grid conditions, it switches to impedance adaptive compensation mode to focus on maintaining stability. This design breaks through the limitations of traditional single-mode systems, enabling the system to adapt to both near-grid strong grid scenarios and remote weak grid needs, covering a wider range of grid connection conditions.

[0039] 4. The overall control architecture of this invention adopts a layered design. From signal acquisition and state determination to control execution and drive output, the logic of each link is clear and the hierarchy is distinct. It does not rely on complex dedicated hardware and can be implemented on general-purpose digital controllers (such as DSPs and FPGAs). At the same time, it is flexible in parameter adjustment and has low modification costs. It can be directly adapted to existing grid-connected converters, which facilitates rapid promotion and implementation in the fields of new energy power generation and energy storage. Attached Figure Description

[0040] Figure 1This is a block diagram of the overall control architecture of the VSG deadbeat predictive control method based on impedance identification and adaptive compensation according to the present invention.

[0041] Figure 2 This is a schematic diagram of control delay in a digital control system;

[0042] Figure 3 Comparison chart of identification results for resistance components of power grid lines;

[0043] Figure 4 Comparison chart of inductance component identification results for power grid lines;

[0044] Figure 5 This is a waveform diagram of the grid-connected voltage of the method of the present invention;

[0045] Figure 6 This is a waveform diagram of the grid-connected current in the method of the present invention;

[0046] Figure 7 This is an FFT analysis diagram of the grid-connected current in the method of the present invention;

[0047] Figure 8 The grid-connected voltage waveform diagram is for traditional VSG control.

[0048] Figure 9 The waveform diagram of grid-connected current under traditional VSG control;

[0049] Figure 10 FFT analysis diagram of grid-connected current for traditional VSG control;

[0050] Figure 11 The waveform diagram is a simulation test result of symmetrical voltage drop in the power grid.

[0051] Figure 12 This is a waveform diagram of the grid-connected current response of the method of the present invention when the grid voltage drops;

[0052] Figure 13 The waveform diagram of the grid voltage drop test corresponding to traditional VSG control;

[0053] Figure 14 This is a waveform diagram of the grid-connected current response of a traditional VSG control when the grid voltage drops. Detailed Implementation

[0054] The present invention will be further described below with reference to embodiments.

[0055] Example 1: A deadbeat predictive control method for VSG based on impedance identification and adaptive compensation, comprising the following steps:

[0056] Step 1: Collect the voltage and current at the grid connection point of the three-phase grid-connected converter, and obtain the voltage and current components in the rotating coordinate system through coordinate transformation;

[0057] Step 2: Identify the grid impedance based on the voltage and current components to obtain the grid impedance parameters, and calculate the system short-circuit ratio based on the grid impedance parameters;

[0058] Step 3: Compare the short-circuit ratio with a preset threshold, and select to enter the standard predictive control mode or the impedance adaptive compensation mode based on the comparison result.

[0059] Step 4: Under the standard predictive control mode, construct a discretized mathematical model of a virtual synchronous generator that takes into account system delay, and perform deadbeat predictive current control based on the discretized mathematical model of the virtual synchronous generator to generate the first control voltage.

[0060] Step 5: In the impedance adaptive compensation mode, based on the first control voltage, an adaptive compensation based on the grid impedance parameters is introduced to generate the final control voltage.

[0061] Step 6: Generate a PWM drive signal based on the final control voltage to control the three-phase grid-connected converter to operate in grid-connected mode.

[0062] Specifically, Figure 1 The overall control architecture block diagram of the VSG deadbeat predictive control method based on impedance identification and adaptive compensation of the present invention is shown, including:

[0063] I. Main Circuit Section: Hardware Topology of Three-Phase Grid-Connected Converter;

[0064] DC side: DC power supply With DC capacitor Provides a stable DC voltage for the converter.

[0065] Converter main body: 6 SiC-MOSFET switches form a three-phase full bridge, responsible for DC-AC power conversion.

[0066] Filtering stage: Filter inductor Filter capacitor and damping resistor And the filter inductor Lt is used to filter out high-frequency harmonics at the converter output.

[0067] Grid connection stage: Connected to the actual power grid via relay K1 to switch between grid-connected and off-grid states; the actual power grid includes the ideal power grid and grid impedance. .

[0068] II. Control Strategy Section: Divided into three layers of logic: signal processing, VSG outer loop, and dual-mode inner loop;

[0069] 1. Signal processing: This includes coordinate transformation, which involves collecting the current, capacitor voltage, grid current, and grid voltage at the grid connection point and converting them into components in the dq rotating coordinate system through Clark / Park transformation for easier control calculations.

[0070] 2. VSG outer loop control: Simulates the operating characteristics of a synchronous generator to generate reference commands for the inner loop, including:

[0071] Active-frequency loop: Receives active power commands from the energy management system. Through rotational inertia Damping coefficient The frequency regulation characteristics of the analog synchronous machine, output electrical angular velocity (The phase angle is obtained after integration) ).

[0072] Reactive power-voltage loop: Receives reactive power commands By simulating the voltage regulation characteristics of a synchronous machine through a PI controller, the q-axis component of the output virtual electromotive force is referenced. .

[0073] 3. Dual-mode inner loop control: Based on the grid impedance identification results, two control modes are switched:

[0074] Standard Predictive Control Mode (Strong Grid): When the grid impedance is low (strong grid), the virtual impedance voltage loop generates a current reference command based on the power loop, and uses deadbeat predictive current control (DPCC) to track the VSG outer loop output. Generate the reference voltage for the converter .

[0075] Impedance adaptive compensation mode (weak network): When the grid impedance is high (weak network), the grid impedance is first calculated through the impedance identification module. Grid impedance The DPCC (Power Controller Control) calibrates the parameters and outputs a first voltage. Simultaneously, an adaptive compensation module generates a compensation voltage, which is superimposed on the first voltage output by the DPCC to offset the influence of grid impedance on control performance. Finally, a reference voltage is output. .

[0076] 4. Drive signal generation: This generates the output signal from the inner loop. The voltage is converted into a three-phase reference voltage through inverse Park transformation, and then the SiC-MOSFET is driven by space vector pulse width modulation (SVPWM) to control the switching action of the converter.

[0077] Specifically, in step 1 of the control method described above, voltage and current sensors are used to collect the voltage and current at the grid connection point of the three-phase grid-connected converter. In the digital signal processor, the collected signals are sequentially subjected to Clark transformation (three-phase → two-phase stationary transformation) and Park transformation (two-phase stationary → two-phase rotating transformation) to obtain the voltage in the two-phase rotating coordinate system dq axis. and current The phase angle used in the Park transform is given by the voltage phase generated by the Virtual Synchronous Generator (VSG) algorithm.

[0078] In step 2, this embodiment uses a combination of active and passive detection to identify the power grid impedance.

[0079] Startup Phase: Initial impedance identification is performed using the pseudo-random binary sequence injection method within the active detection approach. The DSP-controlled converter injects a small-amplitude pseudo-random binary sequence (PRBS) disturbance signal into the grid. The voltage and current responses at the grid connection point are simultaneously measured, and Fast Fourier Transform (FFT) analysis is performed on the response signals. By calculating the ratio of the voltage to current spectrum at a specific frequency point, the magnitude and phase of the grid impedance at that frequency are obtained. By scanning multiple frequency points, the grid impedance can be preliminarily obtained. ,in It is the resistance component. It is the reactance component. It is a complex unit.

[0080] During normal operation: Real-time updates are performed using a passive detection method. Utilizing existing background harmonics or natural fluctuations in voltage and current within the power grid, the recursive least squares (RLS) method is employed to analyze the grid resistance components. and reactance component Online identification is performed to achieve real-time updates of impedance parameters.

[0081] In step 3, based on the grid impedance identified in step 2... The system short-circuit ratio (SCR) is calculated using the following formula for calculating the external power grid short-circuit ratio:

[0082]

[0083] in, The effective value of the rated line voltage at the grid connection point. =220V; The rated active power of the converter, =10kW. Set short-circuit ratio threshold. =3, calculate the result Compare with this threshold:

[0084] like ≥ If so, it is judged as a strong network, and the control mode is activated. Enter standard predictive control mode;

[0085] like < If so, it is judged as a weak network, and the control mode is changed. The impedance adaptive compensation mode has been activated.

[0086] In step 4, deadbeat predictive current control is performed under standard predictive control mode. In this mode, a discretized mathematical model of the VSG is constructed and current control is executed. Specifically, the following steps are included:

[0087] Step 4.1: Establish continuous-time state equations

[0088] Due to the operating characteristics of the VSG-controlled simulated synchronous generator, a system model including an LCL filter and grid impedance is established. The continuous-time state equation in the dq coordinate system is shown in equation (1):

[0089] (1)

[0090] In the formula, For the inverter-side filter inductor, For inductance Parasitic resistance; For the LCL filter capacitor, For capacitor Parasitic resistance or passive damping; For grid-side filter inductors, Inductor Parasitic resistance; For grid impedance; , For the flow through the filter inductor The components of the current in the dq coordinate system; , For the flow through the filter inductor The components of the current in the dq coordinate system; , The inverter-side phase voltage components in the dq coordinate system; , For filter capacitors The components of voltage in the dq coordinate system; , The components of the grid-side phase voltage in the dq coordinate system; This is the angular frequency of the power grid.

[0091] Step 4.2: Construct a discretized mathematical model

[0092] To facilitate implementation by a digital controller, equation (1) is discretized. In this embodiment, the forward Euler method is used to obtain the discrete mathematical model of the VSG current inner loop under the dq axis, as shown in equation (2):

[0093] (2)

[0094] In the formula, For switching cycles; , , and They are respectively Time-state quantity , , and The instantaneous value; , , and They are respectively Time-state quantity , , and The instantaneous value; , For the first Average output voltage of grid-connected inverter within one switching cycle; , , , They are respectively Time and Time-state quantity , The instantaneous value; , For the first Average grid voltage over one switching cycle.

[0095] Step 4.3: Derivation of the Deadbeat Predictive Current Control Law

[0096] The core idea of ​​deadbeat control is to make the current at the next moment accurately track its reference value. From the ideal model of equation (2), the ideal control voltage without considering the delay can be obtained.

[0097] set up , and , Inverter-side current , and grid-connected current , The target value of the state variable; , Capacitor voltage , The target value, ignoring parasitic parameters, is obtained from the discrete equation of equation (2), which contains the target expected value. The difference between this and equation (2) is then used to obtain equation (3), where the subscripts are... Indicates error:

[0098] (3)

[0099] When the switching cycle is sufficiently short, the grid voltage and angular frequency can be considered constant within one control cycle, i.e.:

[0100] (4)

[0101] To simplify the control expression, the inverter-side current is used. , and grid current , Indicates capacitor voltage , The relationship between the three is obtained:

[0102] (5)

[0103] Therefore, the inverter output voltage control target can be derived as follows:

[0104] (6)

[0105] Step 4.4, Digital Delay Compensation

[0106] In digital systems, there is a delay of one control cycle from current sampling to the generation of a given voltage, such as... Figure 2 As shown, the impact of this delay on the control objective needs to be considered.

[0107] In actual program implementation, the current inverter output voltage is used. , Based on this, the control objective should be Actual current at any time and The current value is constant, meaning the discrete predictive control quantity is predicted one step ahead, while the reference current is delayed one step backward:

[0108] (7)

[0109] According to equations (6) and (7), the deadbeat predictive current control equation for compensating for time delay can be obtained:

[0110] (8)

[0111] Subtracting equation (6) from equation (8) yields the inverter output voltage control equation containing grid impedance:

[0112] (9)

[0113] Without loss of generality, let the grid-side current error be... , and inverter side current , There is a functional relationship between the error quantities:

[0114] (10)

[0115] In the formula, As constant coefficients, substituting equation (10) into equation (9) yields the new governing equation:

[0116] (11)

[0117] Linear interpolation can be used for... The current at any given time is estimated as shown in equation (12):

[0118] (12)

[0119] Substituting equation (13) into equation (11), we can obtain the improved deadbeat predictive current control law for the three-phase LCL grid-connected inverter VSG used to compensate for digital delay, and generate the first control voltage. and .

[0120] (13)

[0121] In step 5, after the system enters the impedance adaptive compensation mode, adaptive compensation is started based on the first control voltage generated in step 4.

[0122] Impedance feedforward compensation: The grid impedance identified in step 2 in real time... The voltage is directly substituted into the control voltage calculation equation of the standard predictive control mode (i.e., it is no longer zero) to partially offset the effect of grid impedance.

[0123] Adaptive controller compensation: Simultaneously, a model reference adaptive controller is activated. This controller takes the grid-connected current error as input and dynamically adjusts the output to a compensation voltage using an adaptive law derived from Lyapunov stability theory. , .

[0124] The first control voltage is added to the compensation voltage to obtain the final control voltage applied to the current control cycle.

[0125] In step 6, the final control voltage in the dq coordinate system is subjected to inverse Park transformation to obtain the voltage vector in the two-phase stationary coordinate system. Then, the corresponding PWM pulse signal is generated in the DSP through the space vector modulation (SVPWM) algorithm to drive the power switching devices of the three-phase inverter bridge to achieve precise control of the grid-connected current.

[0126] To verify the effectiveness of this invention, a simulation model of a three-phase grid-connected inverter based on VSG was built on MATLAB / Simulink, and the main parameters were set as shown in Table 1:

[0127] variable parameter variable parameter Rated power 10kW Switching frequency fs 10kHz Rated grid voltage 220Vac Grid frequency fn 50Hz Inverter-side inductor 3.3mH DC bus voltage Udc 800V Filter capacitor 20μF DC bus capacitor Cdc 2mF Grid-side inductor 3mH Grid impedance Zg (0.5+j1.9)Ω

[0128] Table 1

[0129] Figure 3 and Figure 4 The power line resistance components estimated by online identification of power grid impedance are respectively... and inductive component Grid impedance The errors were 1.9% and 0.8%, respectively.

[0130] Set short-circuit ratio threshold =3, then the short-circuit ratio of the external power grid of the converter is If 2.5 < 3, then it is judged as a weak network, and the control mode is changed. The impedance adaptive compensation mode has been activated.

[0131] Figure 5 and Figure 6 These are waveforms of grid-connected voltage and current obtained by using improved deadbeat control in the virtual synchronous generator deadbeat predictive current control method based on impedance identification and adaptive compensation according to the present invention. Figure 6 This is an FFT analysis graph of the grid-connected voltage and current of this invention. Figure 5 Given a desired current amplitude of 21.43A, the actual output value is 21.36A, indicating that the prediction accuracy is relatively high. Figure 7 The horizontal axis represents the harmonic order n, and the vertical axis represents the content of each harmonic. As can be seen from the figure, the grid-connected current THD content of the method proposed in this invention is 0.48%, and the current waveform quality is high.

[0132] Figure 8 and Figure 9 These are the waveforms of grid-connected voltage and current under traditional VSG control. Figure 10 This is an FFT analysis diagram of the grid-connected voltage and current for traditional VSG control. Figure 8Given a desired current amplitude of 21.43A, the actual output value is 21.08A, indicating that the control accuracy is relatively low. Figure 10 The horizontal axis represents the harmonic order n, and the vertical axis represents the content of each harmonic. As can be seen from the figure, the THD content of the grid-connected current using the traditional method is 1.86%, and the current waveform quality is poor.

[0133] Figure 12 In the present invention, the deadbeat predictive current control method for virtual synchronous generators based on impedance identification and adaptive compensation utilizes the grid-connected current obtained by improved deadbeat control at 1 second relative to the grid voltage. Figure 11 The current waveform at the grid-side inductor of the inverter that experiences a symmetrical drop (drop depth 90%) has a short response time of only 30ms, fast dynamic response, and small overshoot.

[0134] Figure 14 The grid-connected current controlled by traditional VSG is at 1 second, and the grid voltage is ( Figure 13 The current waveform at the grid-side inductor of the inverter that experiences a symmetrical drop (drop depth 90%) has a long response time of 200ms, slow dynamic response, and large overshoot.

[0135] Simulation results show that:

[0136] Under weak grid conditions, the total harmonic distortion (THD) of the grid-connected current using the method of this invention is as low as 0.48%, and the waveform quality is far superior to that of traditional VSG control.

[0137] When the grid voltage drops, the system's dynamic response time is only 30ms, demonstrating excellent dynamic performance;

[0138] The power grid impedance identification module can accurately track impedance changes with an error of less than 5%, providing a reliable basis for mode switching and adaptive compensation.

[0139] Example 2: A system for implementing the VSG deadbeat predictive control method based on impedance identification and adaptive compensation described in Example 1, comprising:

[0140] The signal acquisition and coordinate transformation unit is used to acquire the voltage and current at the grid connection point of the three-phase grid-connected converter, and perform coordinate transformation to output the voltage and current components in the rotating coordinate system.

[0141] The power grid impedance identification and status determination unit has its input end connected to the output end of the signal acquisition and coordinate transformation unit. It is used to perform power grid impedance identification, calculate the short-circuit ratio and determine the power grid status, and output a mode selection signal.

[0142] The deadbeat prediction control unit has its input terminal connected to the output terminal of the signal acquisition and coordinate transformation unit and the output terminal of the virtual synchronous generator outer loop controller, respectively. It is used to receive the voltage component, current component and reference current command, and is activated in the standard predictive control mode to output the first control voltage.

[0143] An adaptive compensation unit, whose input terminal is connected to the output terminal signal of the power grid impedance identification and state determination unit, is used to receive the power grid impedance parameters and is activated in the impedance adaptive compensation mode to output the adaptive compensation amount.

[0144] The signal synthesis and PWM generation unit has its input terminals connected to the output terminals of the deadbeat prediction control unit and the adaptive compensation unit, respectively, and is used to synthesize the first control voltage and the adaptive compensation amount to generate the final control voltage.

[0145] Example 3: This example provides an electronic device that implements Example 1, which is presented in the form of a general-purpose computing device. The components of the electronic device may include, but are not limited to: at least one processing unit, at least one storage unit, a bus connecting different system components (including the storage unit and the processing unit), and a display unit.

[0146] The storage unit stores program code, which can be executed by the processing unit to perform the steps described in the method section of Embodiment 1 above, according to various exemplary embodiments of the present invention.

[0147] The storage unit may include readable media in the form of volatile storage units, such as random access memory (RAM) and / or cache storage units, and may further include read-only memory (ROM).

[0148] The storage unit may also include a program / utility having a set (at least one) of program modules, including but not limited to: an operating system, one or more application programs, other program modules, and program data, each or some combination of these examples may include an implementation of a network environment.

[0149] A bus can represent one or more of several types of bus structures, including a memory cell bus or memory cell controller, a peripheral bus, a graphics acceleration port, a processing unit, or a local bus that uses any of the various bus structures.

[0150] The electronic device can also communicate with one or more external devices (e.g., keyboards, pointing devices, Bluetooth devices, etc.), one or more devices that enable a user to interact with the electronic device, and / or any device that enables the electronic device to communicate with one or more other computing devices (e.g., routers, modems, etc.). This communication can be performed via input / output (I / O) interfaces. Furthermore, the electronic device can communicate with one or more networks (e.g., local area networks (LANs), wide area networks (WANs), and / or public networks, such as the Internet) via a network adapter. The network adapter communicates with other modules of the electronic device via a bus. Further, other hardware and / or software modules can be used in conjunction with the electronic device, including but not limited to: microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives, and data backup storage systems.

[0151] From the above description of the embodiments, those skilled in the art will readily understand that the embodiments described herein can be implemented by software or by combining software with necessary hardware. Therefore, the technical solutions according to the embodiments of this disclosure can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (such as a CD-ROM, USB flash drive, external hard drive, etc.) or on a network, including several instructions to cause a computing device (such as a personal computer, server, terminal device, or network device, etc.) to execute the methods according to the embodiments of this disclosure.

[0152] In exemplary embodiments of this disclosure, a computer-readable storage medium is also provided, on which a program product capable of implementing the methods described above is stored. In some possible embodiments, various aspects of the invention may also be implemented as a program product comprising program code that, when the program product is run on a terminal device, causes the terminal device to perform the steps of the various exemplary embodiments of the invention described in the "Exemplary Methods" section above.

[0153] The above description of the embodiments is provided to enable those skilled in the art to understand and apply the present invention. Those skilled in the art can readily make various modifications to the above embodiments and apply the general principles described herein to other embodiments without creative effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made to the present invention by those skilled in the art based on the disclosure thereof should be within the scope of protection of the present invention.

Claims

1. A VSG deadbeat predictive control method based on impedance identification and adaptive compensation, characterized in that: Includes the following steps: Step 1: Collect the voltage and current at the grid connection point of the three-phase grid-connected converter, and obtain the voltage and current components in the rotating coordinate system through coordinate transformation; Step 2: Identify the grid impedance based on the voltage and current components to obtain the grid impedance parameters, and calculate the system short-circuit ratio based on the grid impedance parameters; Step 3: Compare the short-circuit ratio with a preset threshold, and select to enter the standard predictive control mode or the impedance adaptive compensation mode based on the comparison result. Step 4: Under the standard predictive control mode, construct a discretized mathematical model of a virtual synchronous generator that takes into account system delay, and perform deadbeat predictive current control based on the discretized mathematical model of the virtual synchronous generator to generate the first control voltage. Step 5: In the impedance adaptive compensation mode, based on the first control voltage, an adaptive compensation based on the grid impedance parameters is introduced to generate the final control voltage. Step 6: Generate a PWM drive signal based on the final control voltage to control the three-phase grid-connected converter to operate in grid-connected mode.

2. The VSG deadbeat predictive control method based on impedance identification and adaptive compensation according to claim 1, characterized in that: In step 2, the power grid impedance identification adopts an active detection method, a passive detection method, or a combination of both; wherein, the active detection method includes injecting a disturbance signal of a specific frequency into the power grid and analyzing the response, and the passive detection method includes using the inherent harmonics or natural fluctuations of the power grid for parameter identification.

3. The VSG deadbeat predictive control method based on impedance identification and adaptive compensation according to claim 1, characterized in that: In step 2, the formula for calculating the system short-circuit ratio is as follows: ； in, The effective value of the rated line voltage at the grid connection point. The magnitude of the grid impedance. This refers to the rated active power of the converter.

4. The VSG deadbeat predictive control method based on impedance identification and adaptive compensation according to claim 1, characterized in that: The discretized mathematical model of the virtual synchronous generator is established in the following way: Establish a continuous-time state equation that includes the LCL filter and the grid impedance; The continuous-time state equation is discretized using the forward Euler method, the backward Euler method, or the trapezoidal integral method to obtain a discretized mathematical model.

5. The VSG deadbeat predictive control method based on impedance identification and adaptive compensation according to claim 1, characterized in that: The deadbeat predictive current control specifically includes: Based on the discretized mathematical model, a deadbeat predictive control law is derived that enables the grid-connected current to track its reference value in the next control cycle. The reference current and the sampled current are predicted and delayed to eliminate the digital delay of at least one control cycle, thereby generating the first control voltage.

6. The VSG deadbeat predictive control method based on impedance identification and adaptive compensation according to claim 1, characterized in that: In step 5, the adaptive compensation is implemented by an adaptive controller. Specifically, the identified grid impedance parameters are substituted into the calculation equation of the control voltage. At the same time, the adaptive controller dynamically outputs a compensation voltage based on the tracking error of the grid-connected current. The compensation voltage is superimposed with the first control voltage to generate the final control voltage.

7. The VSG deadbeat predictive control method based on impedance identification and adaptive compensation according to claim 1, characterized in that: The adaptive controller employs a model-based adaptive control strategy or a model-free adaptive optimization strategy. The model-based adaptive control strategy is either model reference adaptive control or adaptive control based on Lyapunov stability theory. The model-free adaptive optimization strategy is extreme value search control, fuzzy logic control, or neural network adaptive control.

8. A system for implementing the VSG deadbeat predictive control method based on impedance identification and adaptive compensation as described in any one of claims 1-7, characterized in that, include: The signal acquisition and coordinate transformation unit is used to acquire the voltage and current at the grid connection point of the three-phase grid-connected converter, and perform coordinate transformation to output the voltage and current components in the rotating coordinate system. The power grid impedance identification and status determination unit has its input end connected to the output end of the signal acquisition and coordinate transformation unit. It is used to perform power grid impedance identification, calculate the short-circuit ratio and determine the power grid status, and output a mode selection signal. The deadbeat prediction control unit has its input terminal connected to the output terminal of the signal acquisition and coordinate transformation unit and the output terminal of the virtual synchronous generator outer loop controller, respectively. It is used to receive the voltage component, current component and reference current command, and is activated in the standard predictive control mode to output the first control voltage. An adaptive compensation unit, whose input terminal is connected to the output terminal signal of the power grid impedance identification and state determination unit, is used to receive the power grid impedance parameters and is activated in the impedance adaptive compensation mode to output the adaptive compensation amount. The signal synthesis and PWM generation unit has its input terminals connected to the output terminals of the deadbeat prediction control unit and the adaptive compensation unit, respectively, and is used to synthesize the first control voltage and the adaptive compensation amount to generate the final control voltage.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 7.

10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by a processor, it implements the steps of the method as described in any one of claims 1-7.

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