Grid-connected inverter optimization compensation method for inhibiting phase-locked loop influence and broadband resonance

Abstract

The invention belongs to the technical field of power electronics, and particularly discloses a grid-connected inverter optimization compensation method for inhibiting phase-locked loop influence and broadband resonance. According to the invention, the disturbance transfer function is calculated based on the dynamic model of the phase-locked loop, the associated compensation signal is injected into the target axis signal, and the low-frequency control disturbance dynamically introduced by the phase-locked loop is counteracted; superposing the output compensation signal to an associated compensation signal; and according to the composite compensation signal, the output impedance characteristic of the grid-connected inverter in the middle-high frequency band is remodeled. According to the mode, the low-frequency disturbance dynamically introduced by the phase-locked loop is counteracted by injecting the associated compensation signal, and on the basis, an optimization compensation link is newly added, and the output compensation signal is remodeled in the middle-high frequency band, so that the low-frequency disturbance of the phase-locked loop is eliminated on the basis of not changing the structure of the phase-locked loop and main control parameters. And the low-frequency stability and medium-high frequency resonance suppression of the inverter are synergistically improved, so that the wide-frequency-band stability and the electric energy quality of the grid-connected system under the weak power grid condition are effectively enhanced.

Description

Technical Field

[0001] This application belongs to the field of power electronics technology, and more specifically, relates to an optimized compensation method for grid-connected inverters to suppress the effects of phase-locked loops and broadband resonance. Background Technology

[0002] With the large-scale integration of new energy power generation devices, the power system is gradually exhibiting characteristics of a "weak grid," including a high proportion of power electronic equipment, increased grid equivalent impedance, and weakened system strength. Under weak grid conditions, the interaction between the grid-connected inverter and the grid is significantly enhanced, easily leading to low-frequency oscillations and wide-band harmonic resonance problems, seriously affecting the stable operation of the grid-connected system and the quality of output power. In the control system of the grid-connected inverter, the phase-locked loop (PLL) is used to obtain the phase and frequency information of the grid voltage and is a key link in achieving synchronous grid-connected control. However, the PLL itself has dynamic characteristics, and its output phase cannot track the grid voltage phase accurately and in real time under disturbance conditions, resulting in a deviation between the control coordinate system and the actual system coordinate system. This introduces additional disturbances in grid-connected current control, modulation voltage generation, and other aspects. This additional disturbance is particularly evident under weak grid conditions, manifesting as a negative resistance characteristic of the grid-connected inverter's output impedance in the low-frequency band, reducing the system stability margin, and even causing oscillation instability.

[0003] To mitigate the adverse effects of phase-locked loops (PLLs), common methods to improve system stability include directly reducing the PLL bandwidth, altering the PLL structure, or introducing additional active damping. However, these methods have several drawbacks: First, improving stability by reducing PLL bandwidth significantly sacrifices dynamic response performance. Second, altering the PLL or main control structure increases the complexity of the control system design and reduces its engineering applicability. Third, some methods based on small-signal disturbance compensation are only effective in the low-frequency band and have limited ability to suppress mid-to-high frequency harmonics, making it difficult to achieve broadband stability improvements. Therefore, these methods cannot achieve a synergistic improvement in inverter low-frequency stability and mid-to-high frequency resonance suppression without changing the PLL structure and key control parameters. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this application aims to provide an optimized compensation method for grid-connected inverters that suppresses the effects of phase-locked loops (PLLs) and broadband resonances. This method addresses the problem that existing technologies, by directly reducing the PLL bandwidth, altering the PLL structure, or introducing additional active damping, cannot achieve a synergistic improvement in low-frequency stability and mid-to-high-frequency resonance suppression of the inverter without changing the PLL structure and key control parameters.

[0005] To achieve the above objectives, in a first aspect, this application provides a grid-connected inverter optimization compensation method for suppressing the effects of phase-locked loops and broadband resonance, comprising: The dynamic model based on the phase-locked loop calculates the disturbance transfer function introduced into the current control loop and the modulation voltage loop by the voltage disturbance at the common coupling point, and determines the compensation signal associated with the disturbance transfer function and the current operating point. The associated compensation signal is injected into the target axis signal, and the low-frequency control disturbance dynamically introduced by the phase-locked loop is canceled by the compensation signal in the target axis signal; Obtain the compensation signal output by the newly added optimization compensation stage, and superimpose the output compensation signal onto the associated compensation signal to obtain a composite compensation signal; The output impedance characteristics of the grid-connected inverter in the mid-to-high frequency range are reshaped based on the composite compensation signal.

[0006] In one embodiment, the step of calculating the disturbance transfer function introduced into the current control loop and modulation voltage loop by the common coupling point voltage disturbance using the phase-locked loop-based dynamic model includes: Obtain the voltage and current of the target control system; Based on the voltage-current approximation strategy, the grid-connected voltage of the grid-connected inverter is determined according to the voltage, and the grid-connected current of the grid-connected inverter is determined according to the current. Obtain the target axis component perturbation of the voltage at the common coupling point; Based on the dynamic model of the phase-locked loop, the disturbance transfer function introduced into the current control loop and the modulation voltage loop by the common coupling point voltage disturbance is calculated according to the grid-connected voltage, the grid-connected current, the target axis component disturbance, and the axis vector transformation strategy.

[0007] In one embodiment, the steps of determining the grid-connected voltage of the grid-connected inverter based on the voltage and determining the grid-connected current of the grid-connected inverter based on the current, according to the voltage-current approximation strategy, include: The grid-connected current axis current of the grid-connected inverter under steady-state conditions is determined based on the current. Get the current value of the parasitic resistance in the filter inductor; When the current value is not a preset value, the parasitic resistance is isolated, and the grid-connected voltage of the grid-connected inverter is determined according to the voltage to satisfy the relationship equation. The target shaft current for grid connection is determined based on the unity power factor state of the grid-connected inverter. The grid-connected current of the grid-connected inverter is obtained based on the current grid-connected axis current and the target grid-connected axis current, and the grid-connected voltage of the grid-connected inverter is determined based on the relationship equation satisfied by the grid-connected voltage and the modulation voltage.

[0008] In one embodiment, the step of obtaining the compensation signal output by the newly added optimization compensation stage and superimposing the output compensation signal onto the associated compensation signal to obtain a composite compensation signal includes: Obtain the analysis results of the current impedance stability, and determine the modulation voltage path introduced into the branch based on the analysis results; A phase compensation branch corresponding to the newly added optimized compensation stage is introduced into the modulation voltage channel. The compensation center angular frequency is determined based on the inherent resonant frequency of the target filter of the grid-connected inverter and the mid-to-high frequency resonant band of the control loop, and the transfer function of the optimized compensation link is constructed based on the compensation center angular frequency, the Laplace operator, and the phase compensation coefficient. The compensation signal output by the newly added optimized compensation stage is obtained based on the transfer function of the phase compensation branch and the optimized compensation stage, and the output compensation signal is superimposed on the associated compensation signal to obtain a composite compensation signal.

[0009] In one embodiment, the step of reshaping the output impedance characteristics of the grid-connected inverter in the mid-to-high frequency band according to the composite compensation signal includes: The composite compensation signal is input to the target control system; Obtain the additional equivalent admittance of the target control system outputting the composite compensation signal according to the multi-dimensional transfer function, and calculate the additional output impedance based on the additional equivalent admittance; Obtain the original equivalent admittance, and calculate the original output impedance based on the original equivalent admittance; The output impedance characteristics of the grid-connected inverter in the mid-to-high frequency range are reshaped based on the additional output impedance and the original output impedance.

[0010] In one embodiment, after the step of reshaping the output impedance characteristics of the grid-connected inverter in the mid-to-high frequency range according to the composite compensation signal, the method further includes: Construct an equivalent single-input single-output impedance model for a grid-connected inverter; Based on the equivalent single-input single-output impedance model, the phase margin of the target control system at different active and reactive power operating points is calculated according to the inverter equivalent impedance and the grid impedance, respectively. Based on the phase margin, a stable operating feasible region is plotted, and based on the stable operating feasible region, the safe operating boundary of the grid-connected inverter is evaluated.

[0011] Secondly, this application provides a grid-connected inverter optimization compensation device for suppressing the effects of phase-locked loops and broadband resonance, comprising: The determination module is used to calculate the disturbance transfer function introduced into the current control loop and modulation voltage link by the common coupling point voltage disturbance based on the dynamic model of the phase-locked loop, and to determine the compensation signal associated with the disturbance transfer function and the current operating point; An injection module is used to inject the associated compensation signal into the target axis signal and to cancel the low-frequency control disturbance dynamically introduced by the phase-locked loop through the compensation signal in the target axis signal; The superposition module is used to acquire the compensation signal output by the newly added optimization compensation stage, and superimpose the output compensation signal onto the associated compensation signal to obtain a composite compensation signal; The reshaping module is used to reshape the output impedance characteristics of the grid-connected inverter in the mid-to-high frequency range according to the composite compensation signal.

[0012] Thirdly, this application provides an electronic device, comprising: at least one memory for storing a program; and at least one processor for executing the program stored in the memory, wherein when the program stored in the memory is executed, the processor is configured to execute the method described in the first aspect or any possible implementation thereof.

[0013] Fourthly, this application provides a computer-readable storage medium storing a computer program that, when run on a processor, causes the processor to perform the method described in the first aspect or any possible implementation thereof.

[0014] Fifthly, this application provides a computer program product that, when run on a processor, causes the processor to perform the method described in the first aspect or any possible implementation thereof.

[0015] It is understood that the beneficial effects of the second to fifth aspects mentioned above can be found in the relevant descriptions in the first aspect mentioned above, and will not be repeated here.

[0016] Overall, the technical solutions conceived in this application have the following beneficial effects compared with the prior art: (1) Based on the dynamic model of the phase-locked loop, this application calculates the disturbance transfer function introduced into the current control loop and the modulation voltage link by the voltage disturbance at the common coupling point, and determines the compensation signal associated with the disturbance transfer function and the current operating point. The associated compensation signal is injected into the target axis signal to realize the construction of the small signal disturbance compensation path of the grid-connected inverter. The low-frequency control disturbance introduced by the phase-locked loop is canceled by the compensation signal in the target axis signal, thereby improving the phase margin of the system in the low-frequency band.

[0017] (2) Based on the small signal disturbance compensation path, this application adds an optimized compensation link, that is, constructs an optimized compensation path for the mid-to-high frequency band. Specifically, the modulation voltage channel of the introduced branch is determined according to the analysis results of the current impedance stability, and a phase compensation branch corresponding to the newly added optimized compensation link is introduced into the modulation voltage channel. The output compensation signal is superimposed on the associated compensation signal and works together on the control system, thereby reshaping the output impedance characteristics of the grid-connected inverter in the mid-to-high frequency band, improving the phase margin of this frequency band, and suppressing harmonic resonance.

[0018] In summary, this application calculates the disturbance transfer function introduced into the current control loop and modulation voltage loop by the common coupling point voltage disturbance based on the dynamic model of the phase-locked loop, and determines the compensation signal associated with the disturbance transfer function and the current operating point; injects the associated compensation signal into the target axis signal, and cancels the low-frequency control disturbance dynamically introduced by the phase-locked loop through the compensation signal in the target axis signal; obtains the compensation signal output by the newly added optimized compensation link, and superimposes the output compensation signal onto the associated compensation signal to obtain a composite compensation signal; and reshapes the output impedance characteristics of the grid-connected inverter in the mid-to-high frequency band according to the composite compensation signal. Through the above method, the low-frequency disturbance dynamically introduced by the phase-locked loop is canceled by injecting the associated compensation signal. On this basis, an optimized compensation link is added, and the output compensation signal is used to reshape the inverter in the mid-to-high frequency band, achieving a synergistic improvement in the low-frequency stability and mid-to-high frequency resonance suppression of the inverter without changing the phase-locked loop structure and main control parameters. This effectively enhances the broadband stability and power quality of the grid-connected system under weak grid conditions, meeting the requirements for safe and stable operation of the grid-connected inverter under weak grid conditions. Attached Figure Description

[0019] Figure 1 This is one of the flowcharts illustrating the grid-connected inverter optimization compensation method for suppressing the influence of phase-locked loops and broadband resonance provided in the embodiments of this application; Figure 2 This is a schematic diagram of the grid-connected inverter provided in the embodiments of this application; Figure 3 This is a schematic diagram of the small signal compensation structure provided in an embodiment of this application; Figure 4 This is a schematic diagram of the small signal compensation process provided in an embodiment of this application; Figure 5 This is the SISO equivalent model for small-signal compensation control provided in the embodiments of this application; Figure 6 This is a schematic diagram illustrating the influence of multiple harmonics on grid-connected current provided in an embodiment of this application; Figure 7 This is a schematic diagram of the optimized and supplementary control provided in the embodiments of this application; Figure 8 This is a schematic diagram comparing the output impedance provided in the embodiments of this application; Figure 9 This is a schematic diagram of a stable operating feasible domain provided in the embodiments of this application; Figure 10 This is a schematic diagram of the simulation results of small-signal compensation when low-frequency resonance occurs, provided in an embodiment of this application. Figure 11 This is a schematic diagram of the simulation results of optimized small-signal compensation when the network side contains background harmonics, provided in an embodiment of this application. Figure 12 This is a schematic diagram of the simulation results of optimizing small-signal compensation when considering dead-zone effects, provided in an embodiment of this application. Figure 13 This is a schematic diagram of the simulation results of optimized small-signal compensation considering high-frequency harmonic currents provided in the embodiments of this application; Figure 14 This is the second flowchart illustrating the grid-connected inverter optimization compensation method for suppressing the influence of phase-locked loops and broadband resonance provided in the embodiments of this application. Figure 15 This is a schematic diagram of the frequency response characteristics of the phase compensation branch provided in the embodiments of this application; Figure 16 This is a schematic diagram of the module structure of the grid-connected inverter optimization compensation device for suppressing the influence of phase-locked loop and broadband resonance provided in the embodiments of this application; Figure 17 This is a schematic diagram of the structure of the electronic device provided in the embodiments of this application. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0021] In this article, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. The symbol " / " in this article indicates that the related objects are in an "or" relationship; for example, A / B means A or B.

[0022] The terms "first" and "second," etc., used in the specification and claims herein are used to distinguish different objects, not to describe a specific order of objects. For example, "first response message" and "second response message," etc., are used to distinguish different response messages, not to describe a specific order of response messages.

[0023] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0024] Based on this, embodiments of this application provide an optimized compensation method for grid-connected inverters to suppress the effects of phase-locked loops and broadband resonance, referring to... Figure 1 , Figure 1 This is one of the flowcharts illustrating the grid-connected inverter optimization compensation method for suppressing the effects of phase-locked loops and broadband resonance provided in this application embodiment. In this embodiment, the grid-connected inverter optimization compensation method for suppressing the effects of phase-locked loops and broadband resonance includes steps S10 to S40: Step S10: Calculate the disturbance transfer function introduced into the current control loop and modulation voltage loop by the common coupling point voltage disturbance based on the dynamic model of the phase-locked loop, and determine the compensation signal associated with the disturbance transfer function and the current operating point.

[0025] It should be noted that the reference Figure 2 , Figure 2 This is a schematic diagram of a grid-connected inverter, specifically including: a DC voltage source (Udc), a three-phase full-bridge inverter, current sensors, voltage sensors, and a phase-locked loop (PLL). Red indicates the current control loop, and blue indicates the synchronous reference coordinate system PLL. The DC side voltage... U dc The stable DC bus voltage output from the front-end is the energy source for the entire control system. The three-phase full-bridge inverter converts DC power into high-frequency three-phase pulse voltage, forming the core switching arm of the "DC-AC inverter stage". Voltage sensors collect the three-phase grid voltage and send it directly to the phase-locked loop (PLL). Current sensors collect the grid-connected three-phase current for closed-loop control and grid-connected power regulation, as well as for collecting the three-phase current of the filter capacitor. The PLL receives the grid three-phase voltage and, through its internal closed loop (blue dashed box), calculates and outputs the synchronous phase angle and frequency information of the grid voltage in real time. The control system is implemented in a rotating coordinate system and includes a current PI regulator, capacitor current feedback active damping, and a PWM modulator.

[0026] Understandably, since voltage disturbances at the common coupling point are introduced into the current control loop and the modulation voltage loop, it is necessary to calculate the disturbance transfer function introduced into the current control loop and the modulation voltage loop by the voltage disturbance at the common coupling point based on the dynamic model of the phase-locked loop, and determine the compensation signal associated with the disturbance transfer function and the current operating point. This compensation signal can be called the first compensation signal, which is used to offset the low-frequency control disturbances dynamically introduced by the phase-locked loop and improve the phase margin of the system in the low-frequency band.

[0027] It is important to emphasize that, in order to achieve optimized compensation for grid-connected inverters, it is necessary to construct a small-signal disturbance compensation path for the grid-connected inverters, referring to... Figure 3 , Figure 3 This is a schematic diagram of the small-signal compensation structure, specifically divided into a left path and a right path. The left path represents the main control loop and the compensation injection, while the right path represents the disturbance input and transmission path. The phase-locked loop (PLL) is the core connecting the rotating (dq) coordinate system and the stationary (αβ) coordinate system, and is also the main channel for disturbance coupling. (Reference) Figure 4 , Figure 4 This is a flowchart illustrating small-signal compensation, specifically: the left side represents the physical circuit, and the right side represents the control algorithm implementation. Specifically, system disturbances mainly originate from voltage fluctuations at the grid connection point during actual operation. The compensation control loop itself can only obtain voltage information from within the target control system. At this point, two parallel compensation function matrices are used for input. G fb1 and G fb2 It can be represented as: .

[0028] in, G PLL This represents the disturbance transfer function introduced into the current control loop and modulation voltage loop by the voltage disturbance at the point of common coupling. This represents the steady-state component of the output voltage on the q-axis. This represents the steady-state component of the output voltage on the d-axis. This represents the reference value of the grid-connected current on the q-axis. This represents the reference value of the grid-connected current on the d-axis.

[0029] It should be noted that fluctuations in the grid connection point voltage... Voltage information within the target control system In this regard, it is necessary to establish a corresponding mapping relationship. G tf Specifically, it can be expressed as: .

[0030] in, s Represents the Laplace operator. k ppll This represents the proportional gain of the phase-locked loop. k ipll This represents the integral coefficient of the phase-locked loop. This represents the magnitude of the voltage vector at point PCC.

[0031] Understandably, when performing small-signal compensation control analysis, it is necessary to determine the disturbance transfer function. This disturbance transfer function is closely related to the operating point of the system, specifically depending on the voltage and current state variables of each node of the grid-connected inverter, including but not limited to the grid-connected current axis current of the grid-connected inverter under steady-state conditions. Modulation voltage The current axis current of the grid-connected inverter under steady-state conditions. and grid-connected target shaft current .

[0032] Furthermore, the step of calculating the disturbance transfer function introduced into the current control loop and modulation voltage link by the common coupling point voltage disturbance using the phase-locked loop-based dynamic model includes: obtaining the voltage and current of the target control system; determining the grid-connected voltage of the grid-connected inverter based on the voltage and the grid-connected current of the grid-connected inverter based on the current, using a voltage-current approximation strategy; obtaining the target axis component disturbance of the common coupling point voltage; and calculating the disturbance transfer function introduced into the current control loop and modulation voltage link by the common coupling point voltage disturbance using the phase-locked loop-based dynamic model, based on the grid-connected voltage, the grid-connected current, the target axis component disturbance, and the axis vector transformation strategy.

[0033] It should be understood that, since the modulation voltage lacks directly usable sensor signals and cannot be directly input into the control system, it is necessary to use known state variables in the target control system for approximation, i.e., to introduce a voltage and current approximation strategy. Given that the target control system can obtain the voltage vector and grid-connected current vector information at the PCC point, approximation can be made based on the voltage and current of the target control system. That is, the grid-connected voltage of the grid-connected inverter is determined based on the voltage, and the grid-connected current of the grid-connected inverter is determined based on the current. The target axis component disturbance refers to the component disturbance of the common coupling point voltage on the target axis, which can be the q-axis. The axis vector transformation strategy refers to the strategy of transforming the rotating (dq) axis vector to the static (αβ) axis. At this time, based on the dynamic model of the phase-locked loop, the disturbance transfer function introduced into the current control loop and the modulation voltage link by the common coupling point voltage disturbance can be calculated using the axis vector transformation strategy.

[0034] Furthermore, the steps of determining the grid-connected voltage of the grid-connected inverter based on the voltage and the grid-connected current of the grid-connected inverter based on the current, according to the voltage-current approximation strategy, include: determining the current grid-connected axis current of the grid-connected inverter under steady-state conditions based on the current; obtaining the current value of the parasitic resistance in the filter inductor; isolating the parasitic resistance when the current value is not a preset value, and determining the relational equation satisfied by the grid-connected voltage of the grid-connected inverter based on the voltage; determining the grid-connected target axis current based on the unity power factor state of the grid-connected inverter; obtaining the grid-connected current of the grid-connected inverter based on the current grid-connected axis current and the target grid-connected axis current, and determining the grid-connected voltage of the grid-connected inverter based on the relational equation satisfied by the grid-connected voltage and the modulation voltage.

[0035] It should be noted that, for a grid-connected inverter, its grid-connected current axis (d-axis) under steady-state conditions can be expressed as: If the current value of the parasitic resistance in the filter inductor is not the preset value, it indicates that the parasitic resistance in the filter inductor has an impact. In this case, the parasitic resistance in the filter inductor is ignored by isolation. and The following relationship must be satisfied: ,in, This represents the steady-state component of the output voltage on the d-axis. This represents the grid-connected current axis current of the grid-connected inverter under steady-state conditions. Indicates the fundamental angular frequency. L 1 represents the inverter-side inductance. L 2 indicates the grid-side inductance. Indicates flow L The q-axis component of the current of 1. The q-axis component represents the grid-connected current.

[0036] Under normal operating conditions, grid-connected inverters typically operate at unity power factor. In this case, the target axis current for grid connection can be determined based on the unity power factor state of the inverter. Meanwhile, the current amplitude of the filter inductor branch is relatively small. Therefore, the steady-state component of the modulation voltage can be approximated by the voltage at the PCC point. Although this operation ignores the resistive effect in the circuit, in actual scenarios, since the filter has a significant suppression effect on voltage fluctuations, the error caused by this approximation is completely acceptable.

[0037] Step S20: Inject the associated compensation signal into the target axis signal, and use the compensation signal in the target axis signal to cancel the low-frequency control disturbance dynamically introduced by the phase-locked loop.

[0038] Understandably, after determining the compensation signal associated with the disturbance transfer function and the current operating point, the associated compensation signal can be injected into the target axis signal, which can be the q-axis current reference signal or the q-axis modulated voltage signal. At this time, the injected compensation signal can be used to cancel the low-frequency control disturbance dynamically introduced by the phase-locked loop, thereby improving the phase margin of the system in the low-frequency band.

[0039] It should be noted that this embodiment further considers the distribution characteristics of the compensation vector in the q-axis direction. To facilitate the construction of the equivalent single-input single-output SISO impedance model of the grid-connected inverter and to simplify the parameter design and analysis process, it is assumed that the amplitudes of the compensation vector are respectively... and Since no compensation element is introduced for the d-axis, the compensation component in its corresponding direction can be considered zero. At this point, the angle between the compensation vector and the d-axis in the synchronously rotating coordinate system is π / 2. Based on the above relationship, the compensation signal can be equivalently mapped to the stationary coordinate system, referring to the strategy of transforming rotating coordinates to static coordinates. Its mathematical expression is shown in the following equation: .

[0040] in, s Represents the Laplace operator. Represents the imaginary unit. This represents the fundamental angular frequency of the power grid.

[0041] Understandably, after the above equivalent mapping operation, the equivalent model of small-signal compensated control (SISO) in the stationary coordinate system can be obtained, which can be found in the following reference. Figure 5 At this point, the output current expression can be obtained from the small-signal compensated control SISO equivalent model in the stationary coordinate system, specifically: .

[0042] in, K c This represents the gain coefficient of the active damping in the capacitor current feedback. G del This represents the total delay element of the target control system. G pwm This represents the equivalent gain of the PWM modulator. G lcl1 This represents the transfer function from inverter voltage to grid-connected current. G lcl2 This represents the transfer function from the voltage at point PCC to the grid-connected current. Y c This represents the admittance of the filter capacitor. T This represents a scalar constant.

[0043] It should be noted that, as shown in the above expression for the output current, the system's equivalent structure changes after introducing small-signal compensation. Its effect is equivalent to introducing a parallel equivalent impedance into the original grid-connected inverter's output impedance path. This equivalent impedance is used to reshape the system's impedance characteristics, specifically expressed as: .

[0044] in, G I The transfer function of the current regulator is represented. G del This represents the total delay element of the target control system. G pwm This represents the equivalent gain of the PWM modulator. G lcl1 This represents the transfer function from inverter voltage to grid-connected current. T This represents a scalar constant.

[0045] It should be understood that as the frequency range considered for power quality gradually widens, the impact of high-frequency harmonics becomes unavoidable, necessitating optimization of the aforementioned small-signal compensation control. Harmonic sources in the system can be categorized according to their formation principles into background harmonics, dead-zone harmonics, and harmonic currents; for details, please refer to [reference needed]. Figure 6 Since the grid impedance exhibits significant inductive properties, while the inverter displays capacitive characteristics in certain frequency bands, the combination of these two factors can easily lead to resonance problems. By appropriately increasing the phase angle of the inverter's output impedance and compressing its capacitive range, the resonance risk caused by the combined effects of grid background harmonics and inverter nonlinearity can be mitigated to some extent. Based on the above reasons, this embodiment will also improve the small-signal compensation strategy to enhance the power quality performance of the grid-connected inverter over a wide frequency range.

[0046] Step S30: Obtain the compensation signal output by the newly added optimization compensation stage, and superimpose the output compensation signal onto the associated compensation signal to obtain a composite compensation signal.

[0047] It should be understood that, based on the aforementioned impedance stability analysis, high-frequency resonance can be suppressed by increasing the phase margin of the system near the cutoff frequency. Therefore, in addition to the existing signal compensation framework, this embodiment adds an optimized compensation stage, introducing an additional phase compensation branch into the modulation voltage channel as an improved compensation control structure to reshape the inverter's output impedance characteristics in the high-frequency region. To this end, after obtaining the compensation signal output from the newly added optimized compensation stage, the output compensation signal is superimposed on the associated compensation signal to obtain a composite compensation signal.

[0048] Step S40: Reshape the output impedance characteristics of the grid-connected inverter in the mid-to-high frequency band according to the composite compensation signal.

[0049] It should be noted that after obtaining the composite compensation signal through superposition, they can work together on the target control system to reshape the output impedance characteristics of the grid-connected inverter in the mid-to-high frequency band, thereby improving the phase margin of this frequency band and suppressing harmonic resonance.

[0050] Further, step S40 includes: inputting the composite compensation signal to the target control system; obtaining the additional equivalent admittance corresponding to the composite compensation signal output by the target control system according to the multi-dimensional transfer function, and calculating the additional output impedance according to the additional equivalent admittance; obtaining the original equivalent admittance, and calculating the original output impedance according to the original equivalent admittance; and reshaping the output impedance characteristics of the grid-connected inverter in the mid-to-high frequency band according to the additional output impedance and the original output impedance.

[0051] Understandably, for a target control system, after acquiring the composite compensation signal obtained through superposition, it will output an additional equivalent admittance corresponding to the composite compensation signal, and calculate the additional output impedance based on the additional equivalent admittance, i.e., re-derive the SISO impedance model of the system, referring to... Figure 7 , Figure 7 To optimize and supplement the control diagram, specifically: to highlight the role of the improved compensation strategy, only the newly added optimized compensation link is shown in the diagram, indicated by the red box. G cp This represents the transfer function of the optimized compensation stage, and the expression for the determined output current is given here. It can be: .

[0052] Among them, Z o2 Indicates the original output impedance. G cp The transfer function represents the optimization compensation process. G del This represents the total delay element of the target control system. G pwm This represents the equivalent gain of the PWM modulator. G lcl1 It represents the transfer function from inverter voltage to grid current.

[0053] It should be noted that, after obtaining the above expression for the output current, the improved expression for the equivalent output impedance of the inverter can be further determined. Y cp2 Specifically: .

[0054] Among them, Z o2 Indicates the original output impedance. Gcp The transfer function represents the optimization compensation process. G del This represents the total delay element of the target control system. G pwm This represents the equivalent gain of the PWM modulator. G lcl1 This represents the transfer function from inverter voltage to grid-connected current. T This represents a scalar constant.

[0055] It is understood that, in order to evaluate the control effect of the technical solution in this embodiment, the SISO impedance frequency response of the inverter and the grid under various control schemes is given for reference. Figure 8 , Figure 8 The output impedance comparison diagram is as follows: (a) shows the overall comparison curve before and after optimizing small-signal compensation, and (b) shows the equivalent inductance of the power grid. L g =5mH local contrast curve, Z o2 Z represents the original output impedance. o3 The output impedance after signal compensation is shown. It can be seen that, under different grid inductance parameters, the high-frequency crossover points of the system in the unoptimized state are located at several different frequency positions, with corresponding low phase margins. After introducing improved compensation measures, the phase margins at each crossover frequency point are significantly improved, indicating that the inverter's impedance-phase characteristics in the high-frequency region are effectively enhanced, thereby suppressing high-frequency resonance phenomena. It should be noted that although the output impedance amplitude in the low-frequency band decreases after compensation, the phase change is small, and the basic stability characteristics of the system are not significantly affected.

[0056] Furthermore, after step S40, the method further includes: constructing an equivalent single-input single-output impedance model of the grid-connected inverter; based on the equivalent single-input single-output impedance model, calculating the phase margin of the target control system at different active and reactive power operating points according to the inverter equivalent impedance and the grid impedance; drawing a stable operating feasible region based on the phase margin, and evaluating the safe operating boundary of the grid-connected inverter based on the stable operating feasible region.

[0057] It should be noted that, in order to achieve an intuitive assessment of the safe operating boundary of the grid-connected inverter, this embodiment will also calculate the phase margin of the target control system at different active and reactive power operating points after the equivalent single-input single-output impedance model, combined with the grid impedance, so as to plot the feasible region for stable operation. (Reference) Figure 9 , Figure 9 The schematic diagram of the feasible region for stable operation is as follows: st This represents the original feasible domain for which no action was taken. st_cp1 This represents the feasible region for implementing small-signal compensation. st_cp2 The feasible region for which optimized small-signal compensation is adopted is shown. By comparison, it can be seen that after adopting small-signal compensation, the feasible solution space is shrunk to a certain extent, and the feasible operating range still shows a significant expansion, thus verifying the comprehensive advantages of the technical solution of this embodiment in terms of stability and performance improvement.

[0058] It should be understood that this embodiment will also use MATLAB / Simulink tools to simulate and analyze the system of three inverters connected in parallel and generating low-frequency resonance. The inverter parameters and their corresponding symbols and values ​​can be found in Table 1. Table 1:

[0059] It should be noted that the reference Figure 10 , Figure 10 The following diagram illustrates the simulation results of small-signal compensation during low-frequency resonance: (a) shows the simulation results when three inverters are connected to the grid without small-signal compensation, and (b) shows the simulation results when three inverters are connected to the grid with small-signal compensation. The comparison shows that after small-signal compensation, the current and voltage waveforms in the parallel system become significantly smoother, the oscillation amplitude is significantly reduced, and the system's operational stability is effectively improved. Next, a simulation analysis of the inverter's high-frequency resonance can be performed. Simulations are conducted on three different mechanisms of high-frequency resonance, introducing grid-side harmonic voltages containing 11th and 13th harmonic components as disturbance conditions. The optimized small-signal compensation simulation results when the grid side contains background harmonics are obtained. For details, please refer to [reference needed]. Figure 11 Where (a) represents the three-phase output current of the inverter, and (b) represents the grid connection point voltage and FFT (Fast Fourier Transform) analysis results, specifically: the total harmonic distortion (THD) of FFT (1) is 11.53%, the total harmonic distortion (THD) of FFT (2) is 8.91%, the total harmonic distortion (THD) of FFT (3) is 8.72%, and the total harmonic distortion (THD) of FFT (4) is 4.80%. In this embodiment, the dead time is also added to the switching process. Without considering the background harmonics of the power grid, the simulation results of optimized small-signal compensation considering the dead time effect are obtained. For details, please refer to Figure 12Where (a) represents the three-phase output current of the inverter, and (b) represents the voltage amplification and FFT analysis results at the grid connection point, specifically: the total harmonic distortion (THD) of FFT (1) is 11.35%, the total harmonic distortion (THD) of FFT (2) is 4.89%, the total harmonic distortion (THD) of FFT (3) is 4.69%, and the total harmonic distortion (THD) of FFT (4) is 2.36%. In this embodiment, the 11th and 13th harmonics are also injected at the reference current to obtain the simulation results of optimized small-signal compensation considering high-frequency harmonic currents. For details, please refer to Figure 13 Wherein, (a) represents the three-phase output current of the inverter, and (b) represents the voltage amplification and FFT analysis results at the grid connection point, specifically: the total harmonic distortion (THD) of FFT (1) is 12.35%, the total harmonic distortion (THD) of FFT (2) is 6.48%, the total harmonic distortion (THD) of FFT (3) is 6.37%, and the total harmonic distortion (THD) of FFT (4) is 3.48%. From the comparison of the above reference figures, it can be seen that the optimized small-signal compensation control can play a certain role in suppressing high-frequency resonance. In summary, the technical solution of this embodiment can achieve a synergistic improvement in the broadband stability of the grid-connected inverter, and has good engineering application value.

[0060] This embodiment calculates the disturbance transfer function introduced into the current control loop and modulation voltage link by the common coupling point voltage disturbance based on the dynamic model of the phase-locked loop, and determines the compensation signal associated with the disturbance transfer function and the current operating point. The associated compensation signal is injected into the target axis signal, and the low-frequency control disturbance dynamically introduced by the phase-locked loop is canceled out by the compensation signal in the target axis signal. The compensation signal output by the newly added optimized compensation link is obtained, and the output compensation signal is superimposed on the associated compensation signal to obtain a composite compensation signal. The output impedance characteristics of the grid-connected inverter in the mid-to-high frequency band are reshaped according to the composite compensation signal. Through the above method, the low-frequency disturbance dynamically introduced by the phase-locked loop is canceled out by injecting the associated compensation signal. Based on this, an optimized compensation link is added, and the output compensation signal is used to reshape the inverter in the mid-to-high frequency band. This achieves a synergistic improvement in the low-frequency stability and mid-to-high frequency resonance suppression of the inverter without changing the phase-locked loop structure and main control parameters. This effectively enhances the broadband stability and power quality of the grid-connected system under weak grid conditions, meeting the requirements for safe and stable operation of the grid-connected inverter under weak grid conditions.

[0061] In one specific embodiment, this application provides steps for determining the composite compensation signal. Please refer to... Figure 14 , Figure 14 This is the second flowchart illustrating the grid-connected inverter optimization compensation method for suppressing the influence of phase-locked loops and broadband resonance provided in this application embodiment. Step S30 includes steps S301 to S304: Step S301: Obtain the analysis results of the current impedance stability, and determine the modulation voltage channel introduced into the branch based on the analysis results.

[0062] It should be noted that the modulation voltage channel refers to the channel used to introduce improved and optimized small-signal compensation. Based on the current impedance stability analysis results, it is determined that the high-frequency resonance phenomenon can be suppressed by increasing the phase margin of the system near the cutoff frequency. Therefore, it is necessary to determine the modulation voltage channel to be introduced into the branch based on the analysis results.

[0063] Step S302: Introduce a phase compensation branch in the modulation voltage channel that corresponds to the newly added optimized compensation stage.

[0064] Understandably, based on the existing small-signal compensation framework, a phase compensation branch corresponding to the newly added optimized compensation stage can be introduced into the modulation voltage channel as an improvement scheme for the compensation control structure, which is used to reshape the output impedance characteristics of the inverter in the high-frequency region.

[0065] Step S303: Determine the compensation center angular frequency based on the inherent resonant frequency of the target filter of the grid-connected inverter and the mid-to-high frequency resonant band of the control loop, and construct the transfer function of the optimized compensation link based on the compensation center angular frequency, the Laplace operator, and the phase compensation coefficient.

[0066] It should be understood that the compensation center angular frequency refers to the target frequency point at which the optimized compensation stage achieves the maximum phase compensation effect. This compensation center angular frequency can be determined based on the inherent resonant frequency of the target filter of the grid-connected inverter and the mid-to-high frequency resonant band of the control loop. The target filter can be an LCL filter, corresponding to a frequency range of 500Hz to 1200Hz. After determining the compensation center angular frequency, the transfer function of the optimized compensation stage can be constructed by combining the Laplace operator and the phase compensation coefficients, specifically: .

[0067] in, G cp The transfer function represents the optimization compensation process. s Represents the Laplace operator. Indicates the compensated center angular frequency. This represents the phase compensation coefficient.

[0068] It should be noted that the phase compensation coefficient can range from 10 to 50, for reference. Figure 15 , Figure 15 The schematic diagram showing the influence of the frequency response characteristics of the phase compensation branch is as follows: [The diagram shows the curves representing the influence of the phase compensation coefficient.] The compensated center angular frequencies are 15, 20, and 25. Taking 500, 1000, and 1500 as examples, the comparison shows that the phase compensation coefficient... Increasing this value can significantly enhance the phase lift capability of the optimized compensation circuit near the center frequency, while compensating for the center angular frequency... The value of directly determines the frequency position corresponding to the compensation effect, where the current frequency is equal to the compensation center angular frequency. When the amplitude of the phase compensation branch remains at 0dB, it indicates that the amplitude characteristic at that frequency will not change. Therefore, the center frequency can be selected based on the frequency band where the system resonant point is located. In the range below the center frequency, the optimized compensation stage will introduce approximately [missing information - likely a missing word or phrase]. A 20dB amplitude attenuation reduces the equivalent output impedance in the low-frequency range. This characteristic contradicts the design intention of small-signal compensation to improve impedance. Therefore, a trade-off must be struck between the low-frequency impact and high-frequency improvement during parameter selection, ensuring that the compensation does not significantly weaken the low-frequency impedance while effectively improving the phase margin near the high-frequency crossover frequency. Since the system's high-frequency resonance is mainly concentrated in the 500–1200Hz range, this embodiment sets the compensation center frequency to 800Hz and the phase compensation coefficient to 20 to effectively suppress high-frequency resonance while ensuring stable low-frequency performance.

[0069] Step S304: Obtain the compensation signal output by the newly added optimized compensation stage according to the transfer function of the phase compensation branch and the optimized compensation stage, and superimpose the output compensation signal onto the associated compensation signal to obtain a composite compensation signal.

[0070] It is understandable that after obtaining the compensation signal output by the newly added optimized compensation stage based on the transfer function of the phase compensation branch and the optimized compensation stage, the output compensation signal will be superimposed on the associated compensation signal. At this time, the superimposed compensation signal contains multiple compensation signals, and therefore can be called a composite compensation signal.

[0071] This embodiment obtains the analysis results of the current impedance stability and determines the modulation voltage channel of the introduced branch based on the analysis results; introduces a phase compensation branch corresponding to the newly added optimized compensation stage into the modulation voltage channel; determines the compensation center angular frequency based on the inherent resonant frequency of the target filter of the grid-connected inverter and the mid-to-high frequency resonant band of the control loop, and constructs the transfer function of the optimized compensation stage based on the compensation center angular frequency, the Laplace operator, and the phase compensation coefficient; obtains the compensation signal output by the newly added optimized compensation stage based on the transfer function of the phase compensation branch and the optimized compensation stage, and superimposes the output compensation signal onto the associated compensation signal to obtain a composite compensation signal. By using the above method, after determining from the current impedance stability analysis results that the high-frequency resonance phenomenon can be suppressed by increasing the phase margin of the system near the cutoff frequency, a phase compensation branch is introduced into the modulation voltage channel to compensate for the improvement of the control structure. Using the optimal compensation center frequency and phase compensation coefficient, the high-frequency resonance is effectively suppressed while ensuring the stability of low-frequency performance. Then, the compensation signal output by the newly added optimized compensation link is superimposed on the associated compensation signal, thereby effectively improving the accuracy of the obtained composite compensation signal and meeting the requirements for safe and stable operation of grid-connected inverters under weak grid conditions.

[0072] The following describes the grid-connected inverter optimization compensation device for suppressing phase-locked loop (PLL) effects and wideband resonance provided in this application. The grid-connected inverter optimization compensation device for suppressing PLL effects and wideband resonance described below can be referred to in correspondence with the grid-connected inverter optimization compensation method for suppressing PLL effects and wideband resonance described above. Please refer to... Figure 16 , Figure 16 This is a schematic diagram of the module structure of the grid-connected inverter optimization compensation device for suppressing the influence of phase-locked loops and broadband resonance provided in the embodiments of this application, including: The determination module T10 is used to calculate the disturbance transfer function introduced into the current control loop and modulation voltage link by the common coupling point voltage disturbance based on the dynamic model of the phase-locked loop, and to determine the compensation signal associated with the disturbance transfer function and the current operating point.

[0073] The injection module T20 is used to inject the associated compensation signal into the target axis signal and to cancel the low-frequency control disturbance dynamically introduced by the phase-locked loop through the compensation signal in the target axis signal.

[0074] The superposition module T30 is used to acquire the compensation signal output by the newly added optimization compensation stage, and superimpose the output compensation signal onto the associated compensation signal to obtain a composite compensation signal.

[0075] The reshaping module T40 is used to reshape the output impedance characteristics of the grid-connected inverter in the mid-to-high frequency range according to the composite compensation signal.

[0076] This embodiment calculates the disturbance transfer function introduced into the current control loop and modulation voltage link by the common coupling point voltage disturbance based on the dynamic model of the phase-locked loop, and determines the compensation signal associated with the disturbance transfer function and the current operating point. The associated compensation signal is injected into the target axis signal, and the low-frequency control disturbance dynamically introduced by the phase-locked loop is canceled out by the compensation signal in the target axis signal. The compensation signal output by the newly added optimized compensation link is obtained, and the output compensation signal is superimposed on the associated compensation signal to obtain a composite compensation signal. The output impedance characteristics of the grid-connected inverter in the mid-to-high frequency band are reshaped according to the composite compensation signal. Through the above method, the low-frequency disturbance dynamically introduced by the phase-locked loop is canceled out by injecting the associated compensation signal. Based on this, an optimized compensation link is added, and the output compensation signal is used to reshape the inverter in the mid-to-high frequency band. This achieves a synergistic improvement in the low-frequency stability and mid-to-high frequency resonance suppression of the inverter without changing the phase-locked loop structure and main control parameters, thereby effectively enhancing the broadband stability and power quality of the grid-connected system under weak grid conditions.

[0077] It is understood that the detailed functional implementation of each of the above modules can be found in the description of the aforementioned method embodiments, and will not be repeated here.

[0078] It should be understood that the above-described device is used to execute the methods in the above embodiments. The implementation principle and technical effect of the corresponding program modules in the device are similar to those described in the above methods. The working process of the device can be referred to the corresponding process in the above methods, and will not be repeated here.

[0079] Based on the methods in the above embodiments, this application provides an electronic device, please refer to... Figure 17 , Figure 17 This is a schematic diagram of the structure of the electronic device provided in the embodiments of this application.

[0080] It should be noted that the system may include: a processor 10, a communications interface 20, a memory 30, and a communication bus 40. The processor 10, communications interface 20, and memory 30 communicate with each other via the communication bus 40. The processor 10 can invoke logical instructions stored in the memory 30 to execute the methods described in the above embodiments.

[0081] Furthermore, the logical instructions in the aforementioned memory 30 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application.

[0082] Based on the methods in the above embodiments, this application provides a computer-readable storage medium storing a computer program that, when run on a processor, causes the processor to execute the methods in the above embodiments.

[0083] Based on the methods in the above embodiments, this application provides a computer program product that, when run on a processor, causes the processor to execute the methods in the above embodiments.

[0084] It is understood that the processor in the embodiments of this application can be a central processing unit, or other general-purpose processors, digital signal processors, application-specific integrated circuits, field-programmable gate arrays, or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. A general-purpose processor can be a microprocessor or any conventional processor.

[0085] The method steps in this application embodiment can be implemented in hardware or by a processor executing software instructions. The software instructions can consist of corresponding software modules, which can be stored in random access memory, flash memory, read-only memory, programmable read-only memory, erasable programmable read-only memory, electrically erasable programmable read-only memory, registers, hard disks, portable hard disks, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor, enabling the processor to read information from and write information to the storage medium. Of course, the storage medium can also be a component of the processor.

[0086] It is understood that the various numerical designations used in the embodiments of this application are merely for descriptive convenience and are not intended to limit the scope of the embodiments of this application. Those skilled in the art will readily understand that the above descriptions are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for optimizing compensation of grid-connected inverters to suppress the effects of phase-locked loops and broadband resonance, characterized in that, include: The dynamic model based on the phase-locked loop calculates the disturbance transfer function introduced into the current control loop and the modulation voltage loop by the voltage disturbance at the common coupling point, and determines the compensation signal associated with the disturbance transfer function and the current operating point. The associated compensation signal is injected into the target axis signal, and the low-frequency control disturbance dynamically introduced by the phase-locked loop is canceled by the compensation signal in the target axis signal; Obtain the compensation signal output by the newly added optimization compensation stage, and superimpose the output compensation signal onto the associated compensation signal to obtain a composite compensation signal; The output impedance characteristics of the grid-connected inverter in the mid-to-high frequency range are reshaped based on the composite compensation signal.

2. The method as described in claim 1, characterized in that, The steps for calculating the disturbance transfer function introduced into the current control loop and modulation voltage link by the common coupling point voltage disturbance in the dynamic model based on the phase-locked loop include: Obtain the voltage and current of the target control system; Based on the voltage-current approximation strategy, the grid-connected voltage of the grid-connected inverter is determined according to the voltage, and the grid-connected current of the grid-connected inverter is determined according to the current. Obtain the target axis component perturbation of the voltage at the common coupling point; Based on the dynamic model of the phase-locked loop, the disturbance transfer function introduced into the current control loop and the modulation voltage loop by the common coupling point voltage disturbance is calculated according to the grid-connected voltage, the grid-connected current, the target axis component disturbance, and the axis vector transformation strategy.

3. The method as described in claim 2, characterized in that, The steps of determining the grid-connected voltage of the grid-connected inverter based on the voltage and the grid-connected current of the grid-connected inverter based on the current, according to the voltage-current approximation strategy, include: The grid-connected current axis current of the grid-connected inverter under steady-state conditions is determined based on the current. Get the current value of the parasitic resistance in the filter inductor; When the current value is not a preset value, the parasitic resistance is isolated, and the grid-connected voltage of the grid-connected inverter is determined according to the voltage to satisfy the relationship equation. The target shaft current for grid connection is determined based on the unity power factor state of the grid-connected inverter. The grid-connected current of the grid-connected inverter is obtained based on the current grid-connected axis current and the target grid-connected axis current, and the grid-connected voltage of the grid-connected inverter is determined based on the relationship equation satisfied by the grid-connected voltage and the modulation voltage.

4. The method as described in claim 1, characterized in that, The step of obtaining the compensation signal output by the newly added optimization compensation stage and superimposing the output compensation signal onto the associated compensation signal to obtain a composite compensation signal includes: Obtain the analysis results of the current impedance stability, and determine the modulation voltage path introduced into the branch based on the analysis results; A phase compensation branch corresponding to the newly added optimized compensation stage is introduced into the modulation voltage channel. The compensation center angular frequency is determined based on the inherent resonant frequency of the target filter of the grid-connected inverter and the mid-to-high frequency resonant band of the control loop, and the transfer function of the optimized compensation link is constructed based on the compensation center angular frequency, the Laplace operator, and the phase compensation coefficient. The compensation signal output by the newly added optimized compensation stage is obtained based on the transfer function of the phase compensation branch and the optimized compensation stage, and the output compensation signal is superimposed on the associated compensation signal to obtain a composite compensation signal.

5. The method as described in claim 1, characterized in that, The step of reshaping the output impedance characteristics of the grid-connected inverter in the mid-to-high frequency range based on the composite compensation signal includes: The composite compensation signal is input to the target control system; Obtain the additional equivalent admittance of the target control system outputting the composite compensation signal according to the multi-dimensional transfer function, and calculate the additional output impedance based on the additional equivalent admittance; Obtain the original equivalent admittance, and calculate the original output impedance based on the original equivalent admittance; The output impedance characteristics of the grid-connected inverter in the mid-to-high frequency range are reshaped based on the additional output impedance and the original output impedance.

6. The method according to any one of claims 1 to 5, characterized in that, After the step of reshaping the output impedance characteristics of the grid-connected inverter in the mid-to-high frequency range according to the composite compensation signal, the method further includes: Construct an equivalent single-input single-output impedance model for a grid-connected inverter; Based on the equivalent single-input single-output impedance model, the phase margin of the target control system at different active and reactive power operating points is calculated according to the inverter equivalent impedance and the grid impedance, respectively. Based on the phase margin, a stable operating feasible region is plotted, and based on the stable operating feasible region, the safe operating boundary of the grid-connected inverter is evaluated.

7. A grid-connected inverter optimization compensation device for suppressing the influence of phase-locked loops and broadband resonance, characterized in that, include: The determination module is used to calculate the disturbance transfer function introduced into the current control loop and modulation voltage link by the common coupling point voltage disturbance based on the dynamic model of the phase-locked loop, and to determine the compensation signal associated with the disturbance transfer function and the current operating point; An injection module is used to inject the associated compensation signal into the target axis signal and to cancel the low-frequency control disturbance dynamically introduced by the phase-locked loop through the compensation signal in the target axis signal; The superposition module is used to acquire the compensation signal output by the newly added optimization compensation stage, and superimpose the output compensation signal onto the associated compensation signal to obtain a composite compensation signal; The reshaping module is used to reshape the output impedance characteristics of the grid-connected inverter in the mid-to-high frequency range according to the composite compensation signal.

8. An electronic device, characterized in that, include: At least one memory for storing computer programs; At least one processor is configured to execute a program stored in the memory, wherein when the program stored in the memory is executed, the processor is configured to perform the method as described in any one of claims 1-6.

9. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is run on the processor, it causes the processor to perform the method as described in any one of claims 1-6.

10. A computer program product, characterized in that, When the computer program product is run on a processor, the processor causes the processor to perform the method as described in any one of claims 1-6.

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