A virtual impedance cooperative control method and device suitable for a grid-forming converter

Abstract

The application discloses a virtual impedance cooperative control method and device suitable for networked converters, and belongs to the technical field of micro-grid control. The method is as follows: acquiring a common connection point voltage and calculating situation information entropy to quantize a power imbalance state; taking the normalized situation information entropy as input, generating a virtual impedance adjustment amount according to a preset piecewise linear mapping rule; and dynamically adjusting the equivalent output impedance of each networked converter by using the virtual impedance adjustment amount to compensate for line impedance differences and reshape power transmission characteristics. The application realizes accurate power distribution according to capacity of a multi-networked converter parallel system, has smooth dynamic response and remarkable steady-state circulating current suppression effect, and has high robustness and plug-and-play expansion capability.

Description

Technical Field

[0001] This invention belongs to the field of microgrid control technology, and in particular relates to a virtual impedance collaborative control method and device suitable for grid-type converters. Background Technology

[0002] With the continuous increase in renewable energy penetration, islanded microgrids have received widespread attention as a key carrier for achieving local energy consumption and high-reliability power supply. Grid-connected converters, with their ability to autonomously establish and maintain voltage and frequency, have become the core supporting equipment for islanded microgrids. To improve system capacity and power supply redundancy, multiple grid-connected converters typically need to operate in parallel.

[0003] However, in islanded operation mode, due to the dispersed physical locations of each converter, there are significant differences in the line impedance to the point of common coupling, i.e., impedance heterogeneity. This impedance heterogeneity disrupts the ideal droop power distribution relationship, leading to problems such as inaccurate power distribution, increased steady-state circulating current, and decreased dynamic stability among grid-connected converters operating in parallel. Traditional droop control strategies have failed to effectively compensate for line impedance differences, resulting in low power distribution accuracy. While centralized or distributed collaborative control strategies relying on communication networks improve power distribution to some extent, they increase the system's dependence on communication reliability and implementation complexity. Therefore, how to effectively overcome line impedance heterogeneity and achieve accurate autonomous power distribution among multi-grid converters under conditions of no communication dependence or weak communication is an urgent technical problem to be solved. Summary of the Invention

[0004] In view of the above technical problems, this application provides a virtual impedance collaborative control method and device suitable for grid-type converters.

[0005] Firstly, a virtual impedance collaborative control method suitable for grid-connected converters is provided, applied to an islanded microgrid system consisting of n grid-connected converters and a point of common coupling, where n is a positive integer, including:

[0006] Obtain the voltage signal at the point of common connection, and extract a dynamic sequence of voltage amplitude based on the voltage signal;

[0007] Calculate the situation information entropy within the sliding time window based on the dynamic sequence of voltage amplitude;

[0008] Based on the situation information entropy, the virtual impedance adjustment of each grid-type converter is generated, which changes monotonically with the situation information entropy.

[0009] The equivalent output impedance of each grid-type converter is dynamically adjusted using the virtual impedance adjustment amount.

[0010] Based on the adjusted equivalent output impedance, a voltage reference signal is generated for each grid converter, and the output voltage of each grid converter is controlled according to the voltage reference signal, so that the actual output power of each grid converter is distributed according to a preset capacity ratio.

[0011] Optionally, the step of calculating the situation information entropy within the sliding time window based on the dynamic sequence of voltage amplitude includes:

[0012] The voltage amplitude dynamic sequence is subjected to low-pass filtering to obtain the filtered amplitude sequence;

[0013] Within the sliding time window of the amplitude sequence, calculate the absolute deviation sequence relative to the average value of the amplitude sequence;

[0014] The range of values ​​in the absolute deviation sequence is divided into M intervals. The frequency of occurrence of deviation values ​​in each interval is counted, and the empirical probability corresponding to each interval is calculated.

[0015] The situation information entropy is calculated based on the empirical probability, wherein the formula for calculating the situation information entropy is:

[0016] ;

[0017] Where H(t) is the situation information entropy at time t, p m Let M be the empirical probability of the m-th interval, and M be the total number of intervals.

[0018] Optionally, the generation of virtual impedance adjustment values ​​for each grid-type converter, which monotonically changes with the situation information entropy, based on the situation information entropy includes:

[0019] The situation information entropy is normalized to obtain the normalized situation information entropy;

[0020] The virtual impedance adjustment is generated using a preset piecewise linear mapping rule.

[0021] The preset piecewise linear mapping rules include:

[0022] When the normalized situation information entropy is greater than or equal to 0 and less than or equal to the first threshold, the virtual impedance adjustment amount is calculated based on the lower limit of the virtual impedance adjustment amount and the normalized situation information entropy.

[0023] When the normalized situation information entropy is greater than the first threshold and less than or equal to the second threshold, the virtual impedance adjustment amount is calculated based on the lower limit of the virtual impedance adjustment amount, the normalized situation information entropy, and the first threshold.

[0024] When the normalized situation information entropy is greater than the second threshold, the virtual impedance adjustment amount takes the upper limit of the virtual impedance adjustment amount.

[0025] Optionally, the equivalent output impedance of each grid-type converter is dynamically adjusted using the virtual impedance adjustment amount; wherein the adjusted equivalent output impedance satisfies:

[0026] ;

[0027] Among them, Z eq,i R is the equivalent output impedance of the i-th grid-connected converter. i Let X be the line resistance of the i-th grid-connected converter. i Z is the line reactance of the i-th grid-connected converter. v,i This represents the virtual impedance adjustment of the i-th grid-type converter.

[0028] Optionally, the step of generating voltage reference signals for each grid-type converter based on the adjusted equivalent output impedance includes:

[0029] Obtain the actual output active power, actual output reactive power, rated frequency, and rated voltage of each grid-type converter;

[0030] Based on the virtual synchronous generator control law, the output voltage frequency reference value and voltage amplitude reference value of each grid-type converter are calculated;

[0031] A voltage reference signal is generated based on the output voltage frequency reference value and voltage amplitude reference value.

[0032] Optionally, the virtual synchronous generator control law satisfies the following relationship:

[0033] ;

[0034] Where, ω i U is the voltage and frequency reference value for the i-th grid-connected converter. i Here, ω0 is the reference value for the voltage amplitude of the i-th grid-connected converter, U0 is the rated frequency, and k is the rated voltage. p,i Let k be the active power droop factor of the i-th grid-connected converter. q,i Let P be the reactive power droop factor of the i-th grid-connected converter. e,i Q represents the actual output active power of the i-th grid-connected converter. e,i P represents the actual output reactive power of the i-th grid-connected converter. ref,i Q is the active power reference value for the i-th grid-connected converter. ref,i This is the reference value for the reactive power of the i-th grid-type converter.

[0035] Secondly, a virtual impedance coordinated control device suitable for grid-type converters is provided, comprising:

[0036] A voltage amplitude sequence extraction module is used to acquire the voltage signal at the point of common connection and extract a dynamic voltage amplitude sequence based on the voltage signal.

[0037] The situation information entropy calculation module is used to calculate the situation information entropy within the sliding time window based on the dynamic sequence of voltage amplitude.

[0038] The virtual impedance adjustment generation module is used to generate virtual impedance adjustment values ​​for each grid-type converter based on the situation information entropy, which changes monotonically with the situation information entropy.

[0039] An equivalent output impedance adjustment module is used to dynamically adjust the equivalent output impedance of each grid-type converter using the virtual impedance adjustment amount.

[0040] The voltage reference signal generation module is used to generate voltage reference signals for each grid-type converter based on the adjusted equivalent output impedance, and control the output voltage of each grid-type converter according to the voltage reference signals, so that the actual output power of each grid-type converter is distributed according to a preset capacity ratio.

[0041] Thirdly, an electronic device is provided, including a processor, a memory, a communication interface, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the processor, the one or more programs including instructions for performing steps in a virtual impedance coordinated control method for a grid-type converter as described in the first aspect.

[0042] Fourthly, a computer-readable storage medium is provided, the computer-readable storage medium storing a computer program that is executed by a processor to implement a virtual impedance coordinated control method applicable to a grid-type converter as described in the first aspect.

[0043] Beneficial effects:

[0044] This invention describes a virtual impedance collaborative control method and device suitable for grid-connected converters. By constructing a closed-loop control architecture of "sensing-decision-convergence," it first extracts the dynamic information entropy of the point of common coupling voltage to quantify the global power imbalance state and disorder level in real time, solving the problem of traditional control strategies lacking global situational awareness. Then, using normalized situational information entropy as adaptive input, it dynamically adjusts the virtual impedance of each grid-connected converter through piecewise linear mapping rules, actively compensating for line impedance heterogeneity and fundamentally reconstructing the power transmission environment. Finally, it combines a virtual synchronous generator control law to generate a voltage reference signal, achieving precise control of the output voltage. This method, without relying on communication networks or precise line parameters, ensures that the output power of each converter is strictly allocated according to a preset capacity ratio, significantly reducing steady-state circulating current and improving the power allocation accuracy, dynamic response speed, and operational stability of islanded microgrid systems. It provides a highly robust and scalable solution for power collaborative control of plug-and-play microgrids. Attached Figure Description

[0045] Figure 1 This is a flowchart of a virtual impedance collaborative control method applicable to grid-type converters provided in an embodiment of this application;

[0046] Figure 2 This application provides an embodiment of a multi-grid converter parallel system architecture for islanded microgrids.

[0047] Figure 3 This is a control block diagram of a grid-type converter based on dynamic information entropy provided in an embodiment of this application;

[0048] Figure 4 This is a schematic diagram of the situational awareness architecture and information entropy calculation process provided in the embodiments of this application;

[0049] Figure 5 This is a schematic diagram of the virtual impedance piecewise linear dynamic mapping process based on dynamic information entropy provided in the embodiments of this application;

[0050] Figure 6 This is a schematic diagram comparing the active power distribution under different control strategies provided in the embodiments of this application; wherein, (a) is a schematic diagram before adding this strategy, and (b) is a schematic diagram after adding this strategy;

[0051] Figure 7 This is a schematic diagram comparing reactive power distribution under different control strategies provided in the embodiments of this application; wherein, (a) is a schematic diagram before adding this strategy, and (b) is a schematic diagram after adding this strategy;

[0052] Figure 8This is a schematic diagram comparing the circulation suppression effect under different control strategies provided in the embodiments of this application; wherein, (a) is a schematic diagram before adding this strategy, and (b) is a schematic diagram after adding this strategy;

[0053] Figure 9 This is a schematic diagram of state convergence analysis provided in an embodiment of this application;

[0054] Figure 10 This is a structural diagram of the virtual impedance coordinated control device for grid-type converters provided in the embodiments of this application;

[0055] Figure 11 This is a schematic diagram of the structure of the electronic device provided in the embodiments of this application. Detailed Implementation

[0056] The terms "first," "second," "third," "fourth," etc. (if present) in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus. The technical solutions of the embodiments of this application will now be clearly and completely described in conjunction with the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them.

[0057] Example 1:

[0058] To address the aforementioned technical problems, this embodiment provides a virtual impedance coordinated control method suitable for grid-type converters, such as... Figure 1 As shown, it includes the following steps:

[0059] S1: Obtain the voltage signal at the point of common coupling, and extract the dynamic sequence of voltage amplitude based on the voltage signal.

[0060] In this embodiment, each grid-type converter acquires the three-phase voltage signal at the PCC point in real time through a local voltage sensor: Phase A voltage u a Phase B voltage u b C-phase voltage u c The three-phase voltage is transformed to a two-phase stationary αβ coordinate system using Clark transformation, yielding the α voltage component u. α β voltage component u βThrough the amplitude calculation formula The fundamental instantaneous amplitude sequence of the voltage at point PCC is obtained, i.e., the dynamic voltage amplitude sequence U. m This amplitude sequence will serve as the raw data for situational awareness.

[0061] S2: Calculate the situation information entropy within the sliding time window based on the dynamic sequence of voltage amplitude.

[0062] In this embodiment, the calculation of situation information entropy specifically includes the following sub-steps:

[0063] For the dynamic sequence of voltage amplitude U m Low-pass filtering is performed to remove high-frequency switching ripple and measurement noise, resulting in a smooth amplitude sequence μ(t). A fixed-length sliding time window T is selected. ω This window should cover several fundamental frequency periods to capture the dominant dynamics. The window contains N sampling points, N=T. ω / T s (T) s (Sampling period).

[0064] Calculate the magnitude sequence μ(k) within this window relative to its average value. The absolute deviation sequence d(k):

[0065] ;

[0066] Where μ(k) is the filtered amplitude sequence within the sliding time window. Let d(k) be the average value of the amplitude sequence, d(k) be the absolute deviation sequence of the amplitude sequence relative to the average value of the amplitude sequence, and k be the kth sampling point.

[0067] This deviation sequence directly reflects the fluctuation intensity of the PCC voltage. The range of values ​​in the deviation sequence d(k) is divided into M equal intervals (M=10). The frequency n of the deviation sequence d(k) falling into each interval m is counted. m And calculate the empirical probability p for each interval. m =n m / N.

[0068] According to the definition of information entropy in information theory, calculate the situation information entropy H(t) at the current time t:

[0069] ;

[0070] Where H(t) is the situation information entropy at time t, p m Let M be the empirical probability of the m-th interval, and M be the total number of intervals.

[0071] The situational information entropy H(t) is a quantitative indicator of the global power imbalance state of an islanded microgrid system. When the islanded microgrid system is in a state of power balance and stable operation, voltage fluctuations are small, the deviation sequence is concentrated in a few intervals, the probability distribution is concentrated, and the entropy value is small. When the islanded microgrid system experiences power deficits or severe uneven distribution, voltage fluctuations intensify, the deviation sequence distribution tends to be uniform, and the entropy value increases significantly. Therefore, by monitoring the changes in the situational information entropy H(t) in real time, accurate perception of the global situation of the islanded microgrid system can be achieved.

[0072] S3: Based on the situation information entropy, generate the virtual impedance adjustment amount of each grid-type converter that changes monotonically with the situation information entropy;

[0073] In the specific implementation process, the following steps are first taken:

[0074] Step S3.1: Normalize the situation information entropy to obtain the normalized situation information entropy.

[0075] In this embodiment, in order to map the entropy value to a unified control decision range, it needs to be normalized:

[0076] ;

[0077] Among them, H max and H min These represent the empirical maximum and minimum entropy values ​​of an islanded microgrid system under severely unbalanced and steady-state equilibrium conditions, respectively. These values ​​can be determined based on historical operating data or simulations of the islanded microgrid system. The normalized entropy value H... n (t) takes values ​​in the range [0,1].

[0078] S3.2: Based on the preset piecewise linear mapping rules, a virtual impedance adjustment amount is generated based on the normalized situation information entropy.

[0079] Please refer to the following in this embodiment: Figure 5 This application designs a piecewise linear mapping rule to normalize the situation information entropy H. n (t) is directly mapped to the virtual impedance adjustment quantity Z. v,i (t). The specific rule is as follows:

[0080] ;

[0081] Among them, Z v,min Z is the lower limit of the virtual impedance adjustment. v,max Z is the upper limit of the virtual impedance adjustment value, which can be set. v,min =0.1Ω, Z v,min=0.2Ω. First threshold δ1=0.2, second threshold δ2=0.8. k1 is the piecewise linear adjustment coefficient; H(t) is the normalized situation information entropy at time t, Z v,i (t) represents the virtual impedance adjustment of the i-th grid converter at time t.

[0082] The mapping rule has clear physical meaning and engineering feasibility: when the islanded microgrid system is in steady state or under small disturbances, the virtual impedance is taken as a small value to reduce the impact of virtual voltage drop on the output voltage; when the islanded microgrid system is under large disturbances (high entropy value), the virtual impedance is taken as a large value to provide stronger damping and equalization effects, accelerate power redistribution and circulating current suppression; the intermediate region adopts a linear transition to ensure continuous and smooth changes in the control quantity and avoid parameter abrupt changes that may cause new transient shocks.

[0083] This application's implementation extracts the dynamic information entropy of the point of common coupling voltage signal to quantify the global power imbalance of the islanded microgrid system in real time. Using this entropy value as the basis for adaptive adjustment, the virtual impedance parameters of each grid-type converter are dynamically adjusted through a preset piecewise linear mapping rule. This method proactively compensates for the heterogeneity of physical line impedance at its source, reshaping a near-ideal droop power transmission environment. Thus, without relying on prior knowledge of communication networks and line parameters, it achieves precise coordinated power allocation among multiple units and source suppression of circulating currents, significantly improving the operational stability and plug-and-play scalability of the islanded microgrid system.

[0084] S4: The equivalent output impedance of each grid-type converter is dynamically adjusted using the virtual impedance adjustment amount.

[0085] In this embodiment, the virtual impedance adjustment amount Z v,i (t) is superimposed in series to the physical line impedance of the i-th grid converter, resulting in an adjusted equivalent output impedance Z. eq,i satisfy:

[0086] ;

[0087] Among them, Z eq,i R is the adjusted equivalent output impedance of the i-th grid-connected converter. i Let X be the physical line impedance of the i-th grid-connected converter. i Z is the reactance of the i-th grid-connected converter. v,i Z represents the virtual impedance adjustment of the i-th grid-connected converter, where j is the imaginary unit. This is achieved by dynamically adjusting Z... v,i (t) can actively compensate for the heterogeneity of line impedance caused by the different physical locations of each converter.

[0088] This adaptive compensation mechanism makes the equivalent output impedance of each converter tend to be consistent, thereby creating a good impedance environment for the ideal power distribution of droop control.

[0089] S5: Generate voltage reference signals for each grid converter based on the adjusted equivalent output impedance, and control the output voltage of each grid converter according to the voltage reference signals, so that the actual output power of each grid converter is distributed according to the preset capacity ratio.

[0090] In this embodiment, each grid-type converter adopts a virtual synchronous generator control strategy. First, the actual output active power P of each converter is obtained. e,i Actual output reactive power Q e,i The rated frequency ω0 and rated voltage U0 are then used. Based on the active-frequency droop and reactive-voltage droop characteristics of the VSG (Virtual Synchronous Generator), the output voltage frequency reference value ω0 is calculated. i and voltage amplitude reference value U i :

[0091] ;

[0092] Where, ω i U is the voltage and frequency reference value for the i-th grid-connected converter. i Here, ω0 is the reference value for the voltage amplitude of the i-th grid-connected converter, U0 is the rated frequency, and k is the rated voltage. p,i Let k be the active power droop factor of the i-th grid-connected converter. q,i Let P be the reactive power droop factor of the i-th grid-connected converter. e,i Q represents the actual output active power of the i-th grid-connected converter. e,i P represents the actual output reactive power of the i-th grid-connected converter. ref,i Q is the active power reference value for the i-th grid-connected converter. ref,i This is the reference value for the reactive power of the i-th grid-type converter.

[0093] Finally, based on the generated voltage frequency reference value ω i and voltage amplitude reference value U i A pulse width modulation signal is generated through a dual closed-loop control circuit of voltage and current to drive the switching devices of the converter, thereby precisely controlling the amplitude, frequency, and phase of its output voltage. Under this control law, since the equivalent output impedance has been adaptively compensated by the virtual impedance to tend to be consistent, the output power of each converter will be automatically and precisely distributed according to the preset capacity ratio, and circulating current is effectively suppressed.

[0094] Figure 2This is a schematic diagram of a multi-grid-forming converter parallel system structure for an islanded microgrid, provided in an embodiment of this application. The system includes n grid-forming converters (GFCs) using grid-forming control. Each converter is connected to a point of common coupling (PCC) via an LCL filter and line impedance, collectively supplying power to the local load. In the diagram, V... dc,n For n distributed power sources, C n For the nth distributed capacitor, L fn1 Let L be the first filter inductor in the nth LCL filter. fn2 R is the second filter inductor in the nth LCL filter. fn Let C be the impedance in the nth LCL filter. fn Let R be the capacitance in the nth LCL filter. n Let L be the impedance of the nth line. n Z is the inductance of the nth line. line,n Z is the inductive reactance of the nth line. load,k This is the k-th load. Due to the dispersed locations of the distributed power sources, the line impedance R from each converter to the PCC is... i L i The existence of differences, i.e., impedance heterogeneity, is the root cause of power distribution inaccuracies and increased circulating current in traditional droop control.

[0095] Figure 3 This is a schematic diagram of a three-layer closed-loop control architecture of perception-decision-convergence provided in the embodiments of this application. The diagram fully illustrates the control logic closed loop of the method in this embodiment: PCC voltage dynamic u pcc (t) is perceived and the situation information entropy is calculated. H (t) (Perception layer); After normalization and piecewise mapping, the entropy value generates a virtual impedance adjustment quantity Z. v,i (t) (Decision layer); This adjustment is applied to the VSG control loop, changing the equivalent output impedance of the converter, thereby affecting its power output, and finally reflected in the PCC voltage dynamics through electrical coupling, forming a complete closed-loop convergence process (convergence layer).

[0096] It should be noted that the stability of the entire closed-loop control system in the embodiments of this application can be rigorously proven by constructing a consistent Lyapunov function. Define the system state vector X, which includes power tracking error and frequency deviation, and construct a common quadratic Lyapunov function:

[0097] V(X) = X T PX;

[0098] Where P is a positive definite symmetric matrix, V(X) is a quadratic Lyapunov function, X is the system state vector, and T represents the transpose of the corresponding matrix.

[0099] By analyzing the time derivative of V(X) along the trajectory of the entire closed-loop control system It can be proven that under the piecewise adaptive mapping rule designed in this embodiment, there exist first positive constants α>0 and second positive constants β>0, such that... The inequality ≤ -αV(X) + β holds. This inequality indicates that the state of the entire closed-loop control system is uniformly and eventually bounded, and that as the entire closed-loop control system approaches steady state, the state will asymptotically converge to the equilibrium point. This theoretical analysis mathematically guarantees the global stability and reliability of the control method.

[0100] Figure 6 , Figure 7 These figures compare the active and reactive power distribution effects under different control strategies provided in the simulation verification of the embodiments of this application. The simulation conditions are set as follows: the rated capacity ratio of the three grid-type converters is 1:1:2, the load suddenly drops at 1.0 second and recovers at 2.0 seconds. The figures compare traditional droop control, communication-dependent consensus algorithms, and the strategy proposed in this embodiment.

[0101] Figure 6 , Figure 7 Simulation results show that traditional droop control suffers from significant power distribution deviations and continuous fluctuations due to uncompensated impedance differences; the consensus algorithm improves performance in steady state, but exhibits overshoot and oscillations during dynamic processes, such as... Figure 6 (a) Figure 7 As shown in (a); however, after adopting the strategy proposed in this application, the active and reactive power curves of each converter almost completely overlap, strictly allocated according to the 1:1:2 capacity ratio, with a steady-state allocation error of less than 0.5%, a smooth dynamic process without overshoot, and a convergence time of less than 0.1 seconds, as shown in (a). Figure 6 (b) Figure 7 As shown in (b).

[0102] Figure 8 This is a comparison chart of the circulation suppression effects under different control strategies provided in the embodiments of this application. Under the same load disturbance conditions, such as Figure 8 As shown in (a), the peak circulating current of traditional droop control is as high as 13.67A and decays slowly; the peak circulating current of the consensus algorithm is 6.37A; while the strategy proposed in this application significantly limits the peak circulating current to within 0.54A, with a steady-state circulating current below 0.5A. The peak circulating current is reduced by approximately 79.6% compared to traditional droop control. Figure 8As shown in (b). This superior performance stems from the fact that this application uses situational information entropy to drive virtual impedance adaptive adjustment in real time, thereby compensating for impedance heterogeneity at its source and reconstructing a balanced power transmission environment.

[0103] Figure 9 This is a system state convergence analysis diagram provided by an embodiment of this application. The trajectory in the diagram shows that after a load disturbance occurs, the system state point is rapidly attracted from its initial deviation position to the vicinity of the equilibrium point (origin), and converges to a bounded region with a very small radius within approximately 0.15 seconds. This simulation result intuitively verifies the conclusions regarding the globally consistent eventual bounded convergence of the system in the aforementioned theoretical analysis.

[0104] As can be seen, the virtual impedance collaborative control method for grid-type converters described in this application, by constructing a three-layer closed-loop architecture of "sensing-decision-convergence," can achieve accurate sensing and adaptive compensation of the global power imbalance situation of an islanded microgrid system using only locally measurable PCC voltage signals. This method effectively overcomes the adverse effects of line impedance heterogeneity on power distribution, achieves accurate capacity-based power allocation among multiple units and source suppression of circulating current, and significantly improves the operational stability and robustness of the islanded microgrid system under dynamic load changes and capacity asymmetry conditions.

[0105] Example 2:

[0106] This embodiment provides a virtual impedance coordinated control device suitable for grid-type converters, such as... Figure 4 As shown, it includes:

[0107] A voltage amplitude sequence extraction module is used to acquire the voltage signal at the point of common connection and extract a dynamic voltage amplitude sequence based on the voltage signal.

[0108] The situation information entropy calculation module is used to calculate the situation information entropy within the sliding time window based on the dynamic sequence of voltage amplitude.

[0109] The virtual impedance adjustment generation module is used to generate virtual impedance adjustment values ​​for each grid-type converter based on the situation information entropy, which changes monotonically with the situation information entropy.

[0110] An equivalent output impedance adjustment module is used to dynamically adjust the equivalent output impedance of each grid-type converter using the virtual impedance adjustment amount.

[0111] The voltage reference signal generation module is used to generate voltage reference signals for each grid-type converter based on the adjusted equivalent output impedance, and control the output voltage of each grid-type converter according to the voltage reference signals, so that the actual output power of each grid-type converter is distributed according to a preset capacity ratio.

[0112] Figure 10 This is a schematic diagram of another virtual impedance collaborative control device 1000 suitable for grid-type converters provided in this embodiment. The device is applied to islanded microgrid systems and includes an acquisition unit 1001 and a processing unit 1002.

[0113] The acquisition unit 1001 is used to acquire the voltage signal of the common connection point;

[0114] The processing unit 1002 is configured to: extract a dynamic sequence of voltage amplitude based on the voltage signal, and calculate the situation information entropy of the voltage amplitude fluctuation sequence within a sliding time window to quantify the global power imbalance state of the system; normalize the situation information entropy to obtain a normalized situation information entropy; generate a virtual impedance adjustment amount corresponding to each grid-type converter based on the normalized situation information entropy according to a preset piecewise linear mapping rule; dynamically adjust the equivalent output impedance of each grid-type converter using the virtual impedance adjustment amount to compensate for line impedance heterogeneity; generate a voltage reference signal for each grid-type converter based on the adjusted equivalent output impedance, and control the output voltage of each grid-type converter according to the voltage reference signal, so that the actual output power of each grid-type converter is distributed according to a preset capacity ratio.

[0115] It should be understood that the above-described device implementation and method implementation are based on the same inventive concept, and their specific implementation details can be referred to each other, which will not be repeated here.

[0116] Example 3:

[0117] This embodiment provides an electronic device including a processor, a memory, a communication interface, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the processor, and the one or more programs include instructions for performing steps as in one method of the embodiment.

[0118] Please see Figure 11 , Figure 11 This is a schematic diagram of the structure of an electronic device 1100 provided in an embodiment of this application. The electronic device 1100 includes a transceiver 1101, a processor 1102, and a memory 1103. They are connected to each other via a bus 1104. The memory 1103 is used to store computer programs and data, and the processor 1102 is used to execute the computer program stored in the memory 1103 to implement some or all of the steps of any of the methods described in the above method embodiments.

[0119] It should be understood that the electronic devices in this application may include various microgrid controllers, embedded control terminals, industrial control computers, servers, or edge computing nodes, etc. The above-mentioned electronic devices are merely examples and not exhaustive, and include, but are not limited to, the aforementioned electronic devices.

[0120] Example 4:

[0121] This embodiment provides a computer-readable storage medium storing a computer program that is executed by a processor to implement some or all of the steps of the method described in Embodiment 1.

[0122] In one feasible implementation, this application also provides a computer program product, which includes a non-transitory computer-readable storage medium storing a computer program operable to cause a computer to perform some or all of the steps of any of the methods described in the above method embodiments.

[0123] In the above embodiments, the descriptions of each embodiment have their own emphasis. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0124] The embodiments of this application have been described in detail above. Specific examples have been used in this embodiment to illustrate the principles and implementation methods of this application. The description of the embodiments above is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

[0125] It is worth noting that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of protection defined in this application.

Claims

1. A virtual impedance collaborative control method applicable to grid-connected converters, applied to an islanded microgrid system consisting of n grid-connected converters and a point of common coupling, where n is a positive integer, characterized in that... include: Obtain the voltage signal at the point of common connection, and extract a dynamic sequence of voltage amplitude based on the voltage signal; Calculate the situation information entropy within the sliding time window based on the dynamic sequence of voltage amplitude; Based on the situation information entropy, the virtual impedance adjustment of each grid-type converter is generated, which changes monotonically with the situation information entropy. The equivalent output impedance of each grid-type converter is dynamically adjusted using the virtual impedance adjustment amount. Based on the adjusted equivalent output impedance, a voltage reference signal is generated for each grid converter, and the output voltage of each grid converter is controlled according to the voltage reference signal, so that the actual output power of each grid converter is distributed according to a preset capacity ratio.

2. The virtual impedance coordinated control method applicable to grid-type converters according to claim 1, characterized in that, The calculation of the situation information entropy within the sliding time window based on the dynamic sequence of voltage amplitude includes: The voltage amplitude dynamic sequence is subjected to low-pass filtering to obtain the filtered amplitude sequence; Within a sliding time window, calculate the absolute deviation sequence of the amplitude sequence relative to the average value of the amplitude sequence; The range of values ​​in the absolute deviation sequence is divided into M intervals. The frequency of occurrence of deviation values ​​in each interval is counted, and the empirical probability corresponding to each interval is calculated. The situation information entropy is calculated based on the empirical probability, wherein the formula for calculating the situation information entropy is: ； Where H(t) is the situation information entropy at time t, p m Let M be the empirical probability of the m-th interval, and M be the total number of intervals.

3. The virtual impedance coordinated control method applicable to grid-type converters according to claim 1, characterized in that, The virtual impedance adjustment of each grid-type converter, which is generated based on the situation information entropy and varies monotonically with the situation information entropy, includes: The situation information entropy is normalized to obtain the normalized situation information entropy; The virtual impedance adjustment is generated using a preset piecewise linear mapping rule.

4. The virtual impedance coordinated control method applicable to grid-type converters according to claim 3, characterized in that, The preset piecewise linear mapping rules include: When the normalized situation information entropy is greater than or equal to 0 and less than or equal to the first threshold, the virtual impedance adjustment amount is calculated based on the lower limit of the virtual impedance adjustment amount and the normalized situation information entropy. When the normalized situation information entropy is greater than the first threshold and less than or equal to the second threshold, the virtual impedance adjustment amount is calculated based on the lower limit of the virtual impedance adjustment amount, the normalized situation information entropy, and the first threshold. When the normalized situation information entropy is greater than the second threshold, the virtual impedance adjustment amount takes the upper limit of the virtual impedance adjustment amount.

5. The virtual impedance coordinated control method applicable to grid-type converters according to claim 1, characterized in that, The equivalent output impedance of each grid-type converter is dynamically adjusted using the virtual impedance adjustment amount; wherein, the adjusted equivalent output impedance satisfies: ； Among them, Z eq,i R is the equivalent output impedance of the i-th grid-connected converter. i Let X be the line resistance of the i-th grid-connected converter. i Z is the line reactance of the i-th grid-connected converter. v,i This represents the virtual impedance adjustment of the i-th grid-type converter.

6. The virtual impedance coordinated control method applicable to grid-type converters according to claim 1, characterized in that, The generation of voltage reference signals for each grid-type converter based on the adjusted equivalent output impedance includes: Obtain the actual output active power, actual output reactive power, rated frequency, and rated voltage of each grid-type converter; Based on the virtual synchronous generator control law, the output voltage frequency reference value and voltage amplitude reference value of each grid-type converter are calculated; A voltage reference signal is generated based on the output voltage frequency reference value and voltage amplitude reference value.

7. The virtual impedance coordinated control method applicable to grid-type converters according to claim 6, characterized in that, The control law for the virtual synchronous generator satisfies the following relationship: ； Where, ω i U is the voltage and frequency reference value for the i-th grid-connected converter. i Here, ω0 is the reference value for the voltage amplitude of the i-th grid-connected converter, U0 is the rated frequency, and k is the rated voltage. p,i Let k be the active power droop factor of the i-th grid-connected converter. q,i Let P be the reactive power droop factor of the i-th grid-connected converter. e,i Q represents the actual output active power of the i-th grid-connected converter. e,i P represents the actual output reactive power of the i-th grid-connected converter. ref,i Q is the active power reference value for the i-th grid-connected converter. ref,i This is the reference value for the reactive power of the i-th grid-type converter.

8. A virtual impedance coordinated control device suitable for grid-type converters, characterized in that, include: A voltage amplitude sequence extraction module is used to acquire the voltage signal at the point of common connection and extract a dynamic voltage amplitude sequence based on the voltage signal. The situation information entropy calculation module is used to calculate the situation information entropy within the sliding time window based on the dynamic sequence of voltage amplitude. The virtual impedance adjustment generation module is used to generate virtual impedance adjustment values ​​for each grid-type converter based on the situation information entropy, which changes monotonically with the situation information entropy. An equivalent output impedance adjustment module is used to dynamically adjust the equivalent output impedance of each grid-type converter using the virtual impedance adjustment amount. The voltage reference signal generation module is used to generate voltage reference signals for each grid-type converter based on the adjusted equivalent output impedance, and control the output voltage of each grid-type converter according to the voltage reference signals, so that the actual output power of each grid-type converter is distributed according to a preset capacity ratio.

9. An electronic device, characterized in that, The method includes a processor, a memory, a communication interface, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the processor, and the one or more programs include instructions for performing the steps of the method as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that is executed by a processor to implement the method as described in any one of claims 1 to 7.

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