A power coupling analysis method for network-forming type converters based on a dynamic gain matrix

Abstract

The application provides a power coupling analysis method for a grid-forming converter based on a dynamic gain matrix, comprising the following steps: S1, constructing a dynamic analysis model of a GFM based on a power coupling mechanism; S2, using a dynamic relative gain matrix DRGA as an analysis tool to analyze the coupling characteristics of a system dynamic process in the dynamic analysis model; and S3, establishing a GFM grid-connected model, and verifying the correctness and effectiveness of the dynamic relative gain matrix in analyzing the power coupling characteristics of the GFM through simulation analysis. The power coupling analysis method for the grid-forming converter based on the dynamic gain matrix can more accurately reflect the power coupling relationship of the GFM, quantize the power coupling degree under different conditions, and obviously improve the accuracy in the power coupling analysis process of the GFM, compared with a traditional analysis method.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power grid control, and in particular to a power coupling analysis method for grid-forming converters based on a dynamic gain matrix. BACKGROUND

[0002] Under the background of implementing the "double carbon" goal and building a new power system, new energy power generation represented by photovoltaic and wind power is the focus of current development, and photovoltaic and wind power provide necessary inertia support and damping support by connecting to the power grid through power electronic equipment, making the power grid present highly power electronic characteristics, and problems such as overall low inertia and weak damping of the power system occur. GFM can effectively simulate the inertia and damping characteristics of synchronous generators (SG), and can provide certain inertia support to the power grid, so that the converter-based new energy unit has good frequency and voltage support and regulation effect. On the other hand, the new energy power system has complex application scenarios such as impedance equivalent grid connection line and wide range of power angle changes, causing GFM power coupling, which cannot guarantee independent control of active and reactive rings, and has become one of the important factors affecting the stability of GFM and the power grid.

[0003] For example, the publication number CN202311475148. A method and system for analyzing the low-frequency oscillation of a power system by a grid-forming converter, two low-frequency oscillation analysis models of a power system based on a grid-forming converter are established, the damping torque analytical expression of the system is derived, and the influence of the control parameters of the grid-forming converter and the operating conditions of the power system on the low-frequency oscillation is further quantitatively analyzed. The increase of the virtual synchronous machine control parameters and the power synchronization control parameters will make the damping torque of the system increase first and then decrease, and the change of the new energy grid connection position and the power ratio will also make the damping torque of the system increase first and then decrease, that is, there is an optimal grid-forming converter control parameter and new energy grid connection position and power ratio to make the low-frequency oscillation damping of the system maximum. It realizes the accurate analysis of the low-frequency oscillation of the power system connected to the grid by the grid-forming converter from multiple aspects, and provides a reference for the stability research of large-scale new energy connected to the grid by the grid-forming converter.

[0004] Based on the above-mentioned prior art, the equivalent impedance of the transmission line from the output voltage of the converter to the grid voltage is currently assumed to be purely inductive, and the GFM power coupling characteristics are analyzed. However, low-voltage lines often exhibit resistive and inductive characteristics, and GFM has serious power coupling. Or analyze the power coupling of GFM by analyzing the power angle and impedance ratio at the steady-state operating point, but the power angle value at the steady-state operating point of GFM is usually large, which does not meet the constraint of small power angle approximation. SUMMARY

[0005] The application provides a power coupling analysis method for grid-forming converter based on a dynamic gain matrix, to solve the defect that the power coupling characteristic analysis result of the prior art is not accurate.

[0006] In one aspect, the application provides a power coupling analysis method for grid-forming converter based on a dynamic gain matrix, comprising:

[0007] S1, constructing a dynamic analysis model of GFM based on a power coupling mechanism;

[0008] S2, using a dynamic relative gain matrix DRGA as an analysis tool to analyze the coupling characteristics of the system dynamic process in the dynamic analysis model;

[0009] S3, establishing a GFM grid-connected model to verify the correctness and effectiveness of the dynamic relative gain matrix in analyzing the power coupling characteristics of GFM through simulation analysis;

[0010] Wherein:

[0011] When constructing a dynamic analysis model of GFM based on a power coupling mechanism, it comprises:

[0012] S11, analyzing the power transmission characteristics of GFM under large power angle conditions;

[0013] S12, obtaining the influence of line impedance on the power interaction between GFMs;

[0014] S13, constructing a mathematical model that can reflect the dynamic behavior and power coupling relationship of GFM;

[0015] When using a dynamic relative gain matrix to analyze the coupling characteristics, it comprises:

[0016] S21, calculating the dynamic relative gain matrix to quantify the coupling degree between the control variables and output variables of GFM;

[0017] S22, analyzing the change of the dynamic relative gain matrix over time to reveal the evolution law of the coupling characteristics in the system dynamic process;

[0018] When establishing a GFM grid-connected model, it comprises:

[0019] S31, constructing the topological structure of the GFM grid-connected system;

[0020] S32, setting the parameters of GFM and power grid, including power, voltage, current and impedance;

[0021] S33, based on the topological structure and parameters, constructing a simulation model to simulate the operation of the GFM grid-connected system.

[0022] The application provides a power coupling analysis method for a network type converter based on a dynamic gain matrix, wherein the dynamic analysis model comprises a GFM main circuit and a control system circuit.

[0023] The GFM main circuit is used for monitoring and controlling current and voltage signals in real time and transmitting the signals to the control system circuit.

[0024] The control system circuit is used for realizing conversion and control of electric energy through electronic elements in the GFM main circuit, and specifically comprises the following steps.

[0025] The control system circuit generates a control signal according to an input reference signal and a feedback signal, and realizes conversion and control of electric energy through electronic elements in the main circuit structure according to the control signal, meanwhile, sensors and other elements in the main circuit structure also feed back real-time voltage, current and other signals to the power control loop, so as to realize accurate control and adjustment.

[0026] The application provides a power coupling analysis method for a network type converter based on a dynamic gain matrix, wherein the GFM main circuit comprises the following.

[0027] A DC side voltage source V dc is used for providing stable DC voltage input, and comprises a positive electrode and a negative electrode, and is used for receiving electric energy provided by a DC power supply.

[0028] An AC output end comprises three-phase live lines (A phase, B phase and C phase) and a zero line, and is used for providing AC electric energy to a power grid or other loads.

[0029] An equivalent inductance L g and an equivalent resistance R g represent electrical characteristics of a power transmission line between an output end of an LC filter and a power grid, and are connected between the output end of the LC filter and the power grid.

[0030] A converter is used for converting DC voltage into AC voltage and outputting three-phase currents i sk (k=a, b, c), wherein i sk represents output currents of the A phase, the B phase and the C phase respectively, the converter is connected between the DC side voltage source V dc and the AC output end, the converter is composed of a plurality of switching devices, and realizes conversion of electric energy through pulse width modulation (PWM) or other equivalent control strategies.

[0031] An LC filter comprises a filter inductance L, a filter parasitic resistance RL and a filter capacitance C, the LC filter is connected between the DC side voltage source U dc and the power grid, is used for smoothing DC voltage fluctuation and reducing harmonic components, and is connected between an output end of the converter module and the AC output end.

[0032] Grid point current measurement device, respectively connected to the DC input end, AC output end and converter module, for measuring grid point current ik;

[0033] Filter capacitor voltage measurement device, for measuring filter capacitor voltage e ok (k=a, b, c), wherein e ok respectively represent the filter capacitor voltage of phase A, phase B and phase C.

[0034] The grid point current measurement device and the filter capacitor voltage measurement device include voltage sensors, current sensors, temperature sensors, and overcurrent protectors, overvoltage protector elements.

[0035] The control unit is used for receiving signals of filter capacitor voltage e ok , grid point current i k and grid voltage u k , and adopting a double closed-loop control strategy combining current loop control and voltage loop control to realize voltage stability control and power factor correction of the grid, and to ensure stable operation and efficient power generation of the grid-connected power generation unit through real-time monitoring and control of current and voltage signals.

[0036] According to the grid-forming converter power coupling analysis method based on a dynamic gain matrix provided by the application, the control unit comprises:

[0037] The power calculation module is used for calculating or monitoring the output power of the grid-connected power generation unit.

[0038] The virtual impedance control module is used for improving the stability and dynamic response characteristics of the grid by adjusting the parameters of the virtual impedance.

[0039] According to the grid-forming converter power coupling analysis method based on a dynamic gain matrix provided by the application, the control system circuit comprises:

[0040] The active loop APL generates a reference frequency and a phase;

[0041] The reactive loop RPL generates a reference voltage amplitude;

[0042] And the voltage and current double closed-loop tracking reference value generates a converter modulation wave reference signal, the control part of the GFM mainly generates a reference frequency and a phase through the APL, generates a reference voltage amplitude through the RPL, and generates a converter modulation wave reference signal through the voltage and current double closed-loop tracking reference value, that is:

[0043]

[0044] In the formula:

[0045] T set, P set , Q set respectively are reference mechanical torque, reference mechanical power, reference reactive power;

[0046] T e , P e , Q e respectively are electromagnetic torque, electromagnetic power, reactive power;

[0047] wherein P set =T set / ω, ω=dθ / dt;

[0048] J p , D p , J q , D q respectively are active, reactive inertia coefficient and damping coefficient;

[0049] ω0, ω respectively are rated angular frequency and output angular frequency.

[0050] According to the power coupling analysis method of the grid-forming converter based on the dynamic gain matrix provided by the application, the internal voltage and current double closed loop control circuit is set to ensure the following effect of the double loop control. The GFM can be equivalent to a controllable voltage source, when the grid-forming converter is used as a controllable voltage source, the relationship between the output voltage and the output current of the GFM is:

[0051]

[0052] In the formula, ω0 is the working frequency of the GFM, and X g =ω0L g , and the transformation to the frequency domain is obtained:

[0053]

[0054] The complex power output by the converter is represented as:

[0055]

[0056] Substitute formula (2) into formula (3), and get the power expression of the GFM output voltage amplitude and power angle expression through Laplace transformation:

[0057]

[0058] Linearize formula (4) at the steady-state operating point to obtain the power small-signal model, which is:

[0059]

[0060] Wherein each element in the matrix G(s) is represented as:​

[0061]

[0062] In the formula, ΔP, ΔQ, Δδ and ΔE are respectively the small perturbation components of active power, reactive power, power angle and virtual internal electric potential.

[0063] According to the power coupling analysis method of the grid-forming converter based on the dynamic gain matrix provided by the application, the GFM output active power and reactive power are controlled by power angle and voltage amplitude, and the dynamic processes are coupled. In formula (6), the non-diagonal elements of the transfer function matrix are often not equal to 0, and there is coupling between the powers. Considering the power small signal model of the coupling characteristics, when the GFM power coupling characteristic is analyzed, a two-input two-output coupling system is used for power coupling small signal control, and the two-input two-output coupling system is represented as:

[0064] Y(s)=G(s)U(s) (8)

[0065] In the formula, G(s) is the coupling transfer function matrix in formula (7), and U(s) and Y(s) are two-dimensional input and output column vectors, respectively, wherein:

[0066]

[0067] The amplitude-frequency characteristic matrix is obtained from G(s) in formula (6):

[0068]

[0069] According to formula (10), each element is a function of the angular frequency, reflecting the frequency domain dynamic characteristics of the parameter change, and the formula for solving the dynamic relative gain from the amplitude-frequency characteristic is:

[0070]

[0071] Wherein: DRGA(ω) is the dynamic gain matrix of the system, Indicates the Hadamard product, which is the multiplication of the corresponding elements of the matrix.

[0072] On the other hand, the application also provides an electronic device, which comprises a memory, a processor and a computer program stored in the memory and executable on the processor, and the processor implements the power coupling analysis method of the grid-forming converter based on the dynamic gain matrix as described in any of the above aspects when executing the program.

[0073] On the other hand, the application also provides a non-transitory computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to implement the power coupling analysis method of the grid-forming converter based on the dynamic gain matrix as described in any of the above aspects.

[0074] In another aspect, the present application also provides a computer program product comprising a computer program which, when executed by a processor, implements any of the above-mentioned methods for power coupling analysis of grid-forming converter based on dynamic gain matrix.

[0075] The method for power coupling analysis of grid-forming converter based on dynamic gain matrix provided by the present application can more accurately reflect the power coupling relationship of GFM by analyzing the coupling characteristics in the dynamic process of the system using the dynamic relative gain matrix, compared with the traditional analysis method, quantifies the power coupling degree in different situations, and significantly improves the accuracy in the power coupling analysis process of GFM.

[0076] The present application verifies the influence of line impedance on the power coupling characteristics of the converter and the deviation of reactive power control through simulation. These results can directly guide the operation and control of actual power systems, helping to avoid potential problems and risks.

[0077] With the rapid development of new energy and the expansion of grid-connected scale, the power coupling problem of the converter is increasingly prominent, and the present application provides an effective technical means to solve this problem, which is helpful to promote the further development and application of new energy. BRIEF DESCRIPTION OF DRAWINGS

[0078] In order to more clearly illustrate the technical solutions in the present application or prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0079] Figure 1 is a flowchart of the method for power coupling analysis of grid-forming converter based on dynamic gain matrix provided by the embodiments of the present application;

[0080] Figure 2 is a typical GFM grid-connected system topology of the method for power coupling analysis of grid-forming converter based on dynamic gain matrix provided by the embodiments of the present application;

[0081] Figure 3 is a GFM power control loop diagram of the method for power coupling analysis of grid-forming converter based on dynamic gain matrix provided by the embodiments of the present application;

[0082] Figure 4 is a GFM grid-connected equivalent diagram of the method for power coupling analysis of grid-forming converter based on dynamic gain matrix provided by the embodiments of the present application;

[0083] Figure 5A power coupling small signal control block diagram of a networked control of a networked converter power coupling analysis method based on a dynamic gain matrix is provided by the embodiment of the present application.

[0084] Figure 6 A system RGA number change graph when impedance ratio and power angle change is provided by the embodiment of the present application. Figure 6 (a) is a system RGA number change graph when impedance ratio changes, Figure 6 (b) is a system RGA number change graph when power angle changes.

[0085] Figure 7 Simulation result graphs under different impedance ratios are provided by the embodiment of the present application. Figure 7 (a) is a power angle graph under different impedance ratios, Figure 7 (b) is an active power graph under different impedance ratios, Figure 7 (c) is a reactive power graph under different impedance ratios.

[0086] Figure 8 A structural schematic diagram of an electronic device is provided by the embodiment of the present application. DETAILED DESCRIPTION

[0087] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme in the present application will be described clearly and completely below in combination with the drawings in the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0088] The power coupling analysis method based on a dynamic gain matrix of a networked converter provided by the embodiment of the present application will be described below in combination with Figures 1-6

[0089] Figure 1 A flowchart of the power coupling analysis method based on a dynamic gain matrix of a networked converter provided by the embodiment of the present application is shown in the figure.

[0090] As shown in the figure, the power coupling analysis method based on a dynamic gain matrix of a networked converter provided by the embodiment of the present application, the execution subject can be an upper computer, and the method mainly includes the following steps. Figure 1 S1, a dynamic analysis model of a GFM is constructed based on a power coupling mechanism.

[0091]

[0092] ​​S2, using a dynamic relative gain matrix DRGA as an analysis tool, performing coupling characteristic analysis on a system dynamic process in the dynamic analysis model;

[0093] S3, establishing a GFM grid-connected model, and verifying correctness and effectiveness of the dynamic relative gain matrix in analyzing power coupling characteristics of the GFM through simulation analysis;

[0094] Wherein:

[0095] When constructing a dynamic analysis model of the GFM based on a power coupling mechanism, the following steps are included:

[0096] S11, analyzing power transmission characteristics of the GFM under a large power angle condition;

[0097] S12, obtaining an influence of line impedance on power interaction between GFMs;

[0098] S13, constructing a mathematical model capable of reflecting dynamic behavior and power coupling relationship of the GFM;

[0099] Specifically, the dynamic analysis model includes a GFM main circuit and a control system circuit.

[0100] The GFM main circuit is configured to monitor and control current and voltage signals in real time and transmit them to the control system circuit.

[0101] The control system circuit is configured to realize conversion and control of electric energy through electronic elements in the GFM main circuit, and specifically includes:

[0102] The control system circuit generates a control signal according to an input reference signal and a feedback signal, and converts and controls electric energy through electronic elements in the main circuit structure according to the control signal. At the same time, sensors and other elements in the main circuit structure also feed back real-time voltage, current and other signals to the power control loop for accurate control and adjustment.

[0103] Wherein, as shown in Figure 2 , the GFM main circuit structure includes: Figure 2

[0104] A DC side voltage source V dc , configured to provide a stable DC voltage input and including a positive electrode and a negative electrode, for receiving electric energy provided by a DC power supply.

[0105] An AC output end, including three-phase live lines (A phase, B phase and C phase) and a neutral line, for providing AC electric energy to a power grid or other loads.

[0106] An equivalent inductance L g and an equivalent resistance R g ​, which represent the electrical characteristics of the transmission line between the converter output voltage and the grid point voltage, are connected between the output of the LC filter and the grid;

[0107] a converter for converting a DC voltage into an AC voltage and outputting a three-phase current i sk (k = a, b, c), where i sk represent the output currents of the A-phase, B-phase and C-phase respectively, and the converter is connected to a DC-side voltage source V dc and the AC output end, the converter is composed of multiple switching devices, and the conversion of electric energy is realized through pulse width modulation (PWM) or other equivalent control strategies;

[0108] an LC filter including a filter inductor L, a filter parasitic resistance RL and a filter capacitor C, which is connected between the DC-side voltage source U dc and the grid, for smoothing the DC voltage fluctuation and reducing the harmonic component, and is connected between the output of the converter module and the AC output end;

[0109] a grid point current measurement device connected to the DC input end, the AC output end and the converter module respectively, for measuring the grid point current ik;

[0110] a filter capacitor voltage measurement device for measuring the filter capacitor voltage e ok (k = a, b, c), where e ok represent the filter capacitor voltages of the A-phase, B-phase and C-phase respectively;

[0111] The grid point current measurement device and the filter capacitor voltage measurement device include voltage sensors, current sensors, temperature sensors, and overcurrent protectors, overvoltage protector elements.

[0112] a control unit for receiving signals of the filter capacitor voltage e ok , the grid point current i k and the grid voltage u k , and adopting a double closed-loop control strategy combining current loop control and voltage loop control to realize voltage stability control and power factor correction of the grid, and through real-time monitoring and control of the current and voltage signals, to ensure stable operation and efficient power generation of the grid-connected power generation unit;

[0113] More specifically, the control unit includes:

[0114] a power calculation module for calculating or monitoring the output power of the grid-connected power generation unit;

[0115] a virtual impedance control module for improving the stability and dynamic response characteristics of the grid by adjusting the parameters of the virtual impedance;

[0116] The power control part of the GFM is the core, mainly including APL (active loop) and RPL (reactive loop) two parts, and the control block diagram is as shown in Figure 3 The control part of the GFM mainly generates reference frequency and phase through the APL, generates reference voltage amplitude through the RPL, and generates converter modulation wave reference signal through voltage and current double closed loop tracking reference value, that is

[0117]

[0118] In the formula, T set , P set , Q set are reference mechanical torque, reference mechanical power, and reference reactive power respectively; T e , P e , Q e are electromagnetic torque, electromagnetic power, and reactive power respectively; P set =T set / ω, ω=dθ / dt; J p , D p , J q , D q are active and reactive inertia coefficients and damping coefficients respectively; ω0, ω are rated angular frequency and output angular frequency respectively.

[0119] Small signal modeling of GFM

[0120] By setting the internal voltage and current double closed loop control loop, the following effect of the double loop control is ensured. The GFM can be equivalent to a controllable voltage source, and the equivalent circuit is as shown in Figure 4 According to Figure 4 , the relationship between the output voltage and the output current of the GFM is:

[0121]

[0122] In the formula, ω0 is the working frequency of the GFM, and there is X g =ω0L g . Transforming to the frequency domain can obtain:

[0123]

[0124] The complex power output by the converter is represented as:

[0125]

[0126] Substitute equation (2) into equation (3), and get the power expression of the GFM output voltage amplitude and power angle expression through Laplace transform:

[0127]

[0128] Linearizing the equation (4) at the steady state operating point, the power small signal model is obtained as:

[0129]

[0130] Where each element in the matrix G(s) is expressed as:

[0131]

[0132] Where ΔP, ΔQ, Δδ and ΔE are the small perturbation components of active power, reactive power, power angle and virtual internal voltage, respectively.

[0133] GFM power coupling characteristic analysis

[0134] The GFM output active power and reactive power are controlled by power angle and voltage amplitude simultaneously, and the dynamic process is coupled. In the equation (6), the off-diagonal elements of the transfer function matrix are not equal to 0, and there is coupling between the powers. The power small signal model considering the coupling characteristics is shown in the equation (7). Figure 5

[0135] For the two-input two-output coupling system expressed in the equation (7), it can be expressed as: Figure 5

[0136] Y(s)=G(s)U(s) (8)

[0137] Where G(s) is the coupling transfer function matrix in the equation (7), and U(s) and Y(s) are two-dimensional input and output column vectors, respectively; that is:

[0138]

[0139] The amplitude frequency characteristic matrix is obtained from the G(s) in the equation (6) as:

[0140]

[0141] Each element in the equation (10) is a function of angular frequency, which reflects the frequency domain dynamic characteristics of parameter variation. The equation for solving the dynamic relative gain from the amplitude frequency characteristic is:

[0142]

[0143] Where DRGA(ω) is the dynamic gain matrix of the system, The Hadamard product is represented as the multiplication of the corresponding elements of the matrix.

[0144] Based on the above theoretical analysis, the power coupling characteristics of the GFM can be established as: Figure 5 ​​The system's dynamic relative gain matrix. Since dynamic relative gain is a generalization of static relative gain over the entire frequency domain, it possesses the fundamental properties of static relative gain. Like static relative gain, dynamic relative gain also exhibits the same characteristics:

[0145] DRGA11(ω)+DRGA12(ω)=1

[0146] DRGA11(ω)=DRGA22(ω)

[0147] DRGA12(ω)=DRGA21(ω)

[0148] Analogous to static relative gain theory, a larger dynamic relative gain indicates a stronger control effect of the input on the output, and a smaller coupling effect from other control loops. The magnitude of DRGA(ω) directly reflects the degree of coupling in the system. When DRGA(ω) is close to 0, the coupling effect is negligible; a larger DRGA(ω) indicates more severe coupling. To provide a direct comparison of DRGA coupling, the RGA number is introduced for quantitative analysis. By definition, a smaller RGA number indicates lower system coupling.

[0149] RGA number = ||DRGA(ω) - I 2×2 || sum (12)

[0150] from Figure 6 As can be seen, the RGA number changes with frequency, indicating that the coupling degree of the system is different in different frequency bands during dynamic processes. In the mid-frequency band, the DRGA(ω) value changes further with frequency and has a resonant peak. The magnitude of the resonant peak is affected by the change in power angle, and this value is significantly improved compared with the DRGA(ω) value in the low-frequency band.

[0151] Depend on Figure 6 (a) It can be seen that as the impedance ratio R / X decreases, the resonant frequency is around 314 rad / s. The larger the resonant peak value, the deeper the active and reactive coupling of the system near this frequency band during dynamic processes. Figure 6 (b) It can be seen that as the power angle δ increases, the resonant frequency remains around 314 rad / s (example). The larger the resonant peak value, the lower the coupling degree of the system as the impedance ratio increases. Analysis shows that the power coupling degree of the GFM is related to the power angle and the line impedance ratio. As the power angle increases or the impedance ratio decreases, the power coupling degree of the converter continuously deepens. Finally, simulation verification shows that when the line impedance ratio R / X increases, the power angle δ increases, and the reactive power control deviates significantly.

[0152] The application aims at the power coupling problem of GFM, adopts the coupling analysis method based on the dynamic relative gain matrix to analyze the coupling characteristics in the dynamic process of the system, and can more effectively predict and control the unstable factors in the power system.

[0153] Application field

[0154] New energy grid connection: In the new energy grid connection system such as wind energy and solar energy, the grid-connected converter is the key equipment connecting new energy and the grid. The application can help analyze the power coupling characteristics between converters when new energy is connected to the grid, optimize the grid connection control strategy, and improve the stability and efficiency of new energy grid connection.

[0155] Stable operation of power grid: In the power grid, multiple grid-connected converters may operate simultaneously, and the power coupling between them will affect the stability of the power grid. The application can analyze this coupling characteristic to provide theoretical support and technical means for the stable operation of the power grid.

[0156] Design and optimization of power system: In the design and optimization process of the power system, the power coupling characteristics between converters need to be considered to ensure the overall performance and stability of the system. The application provides an effective analysis tool and method to help designers better understand and optimize the performance of the power system.

[0157] Experimental example

[0158] Based on the above embodiment scheme, the application uses MATLAB / Simulink software to build Figure 1 The simulation model of the energy storage VSC is shown in the table 1:

[0159] Table 1 GFM grid connection simulation parameter table

[0160]

[0161] As Figure 7 shown, in the initial state, the GFM stably feeds the active power to the grid at 150kW. Set t at 2s, the active power given value increases by 150kW; as Figure 7 (a) shows that as the line impedance ratio decreases, the power angle gradually increases; as Figure 7 (b) shows that as the line impedance ratio decreases, the active power has no obvious change; as Figure 7 (c) shows that as the line impedance ratio decreases, the reactive power output increases obviously, and the coupling degree is obviously enhanced.

[0162] Figure 8 is a structural schematic diagram of an electronic device provided by an embodiment of the application.

[0163] As Figure 8As shown, the electronic device can include a processor 610, a communications interface 620, a memory 630, and a communications bus 640, wherein the processor 610, the communications interface 620, and the memory 630 complete mutual communication through the communications bus 640. The processor 610 can invoke a logic instruction in the memory 630 to execute a power coupling analysis method for a grid-forming converter based on a dynamic gain matrix, which includes:

[0164] S1, constructing a dynamic analysis model of the GFM based on a power coupling mechanism;

[0165] S2, using a dynamic relative gain matrix DRGA as an analysis tool to analyze coupling characteristics of a system dynamic process in the dynamic analysis model;

[0166] S3, establishing a GFM grid-connected model, and verifying correctness and effectiveness of the dynamic relative gain matrix in analyzing power coupling characteristics of the GFM through simulation analysis;

[0167] In addition, the logic instruction in the memory 630 described above can be implemented in the form of a software function unit and sold or used as an independent product, and can be stored in a computer-readable storage medium. Based on such understanding, the technical solutions of the present application essentially or the part that contributes to the prior art or part of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium, includes a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in the various embodiments of the present application. The foregoing storage medium includes a U disk, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk or an optical disk, and various media that can store program codes.

[0168] On the other hand, the present application also provides a computer program product, which includes a computer program, the computer program can be stored on a non-transitory computer readable storage medium, and the computer program is executed by a processor, so that the computer can execute the power coupling analysis method for a grid-forming converter based on a dynamic gain matrix, which includes: S1, constructing a dynamic analysis model of the GFM based on a power coupling mechanism;

[0169] S2, using a dynamic relative gain matrix DRGA as an analysis tool to analyze coupling characteristics of a system dynamic process in the dynamic analysis model;

[0170] S3, a GFM grid-connected model is established, and correctness and effectiveness of the dynamic relative gain matrix in analyzing the power coupling characteristics of the GFM are verified through simulation analysis.

[0171] In another aspect, the application further provides a non-transitory computer-readable storage medium, which stores a computer program, and the computer program is executed by a processor to implement the method for analyzing power coupling of a network-type converter based on a dynamic gain matrix, and the method comprises the following steps of:

[0172] S2, a dynamic relative gain matrix DRGA is used as an analysis tool to analyze coupling characteristics of a system dynamic process in the dynamic analysis model;

[0173] S3, a GFM grid-connected model is established, and correctness and effectiveness of the dynamic relative gain matrix in analyzing the power coupling characteristics of the GFM are verified through simulation analysis.

[0174] Through the above description of the embodiments, those skilled in the art can clearly understand that the embodiments can be implemented by means of software and a necessary general hardware platform, and of course, can also be implemented by hardware. Based on such understanding, the above technical solutions or the essential part of the prior art can be embodied in the form of a software product, which can be stored in a computer readable storage medium, such as a ROM / RAM, a magnetic disk, an optical disk, etc., and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the method described in each embodiment or some part of the embodiment.

[0175] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the application, and not to limit them; although the application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for some technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the application.

Claims

1. A power coupling analysis method for grid-type converters based on dynamic gain matrices, characterized in that, include: S1. Construct a dynamic analysis model of GFM based on the power coupling mechanism; S2. Using the Dynamic Relative Gain Matrix (DRGA) as an analysis tool, the coupling characteristics of the system dynamic process in the dynamic analysis model are analyzed. S3. Establish a GFM grid-connected model and verify the correctness and effectiveness of the dynamic relative gain matrix in analyzing the power coupling characteristics of GFM through simulation analysis. in: When constructing a dynamic analysis model of GFM based on the power coupling mechanism, the following are included: S11. Analyze the power transfer characteristics of GFM under large power angle conditions; S12. Obtain the effect of line impedance ratio on power interaction between GFMs; S13. Construct a mathematical model that can reflect the dynamic behavior and power coupling relationship of GFM; When using the dynamic relative gain matrix for coupling characteristic analysis, the following are included: S21. Calculate the dynamic relative gain matrix to quantify the degree of coupling between the GFM control variables and the output variables; S22. Analyze the change of the dynamic relative gain matrix over time to reveal the evolution law of coupling characteristics in the dynamic process of the system; When establishing a GFM grid connection model, the following are included: S31. Construct the topology of the GFM grid-connected system; S32. Set the parameters of the GFM and the power grid, including power, voltage, current and impedance; Based on the aforementioned topology and parameters, a simulation model is constructed to simulate the operation of the GFM grid-connected system.

2. The power coupling analysis method for grid-type converters based on dynamic gain matrix according to claim 1, characterized in that, The dynamic analysis model includes the GFM main circuit and the control system circuit. The GFM main circuit is used to monitor and control current and voltage signals in real time and transmit them to the control system circuit. The control system circuit is used to convert and control electrical energy through electronic components in the GFM main circuit, specifically including: The control system circuit generates control signals based on the input reference signals and feedback signals, and converts and controls electrical energy through electronic components in the main circuit structure according to the control signals. At the same time, sensors and other components in the main circuit structure also feed back real-time voltage, current and other signals to the power control loop.

3. The power coupling analysis method for grid-type converters based on dynamic gain matrix according to claim 2, characterized in that, The GFM main circuit includes: DC side voltage source V dc It is used to provide a stable DC voltage input; An LC-type filter includes a filter inductor L, a filter parasitic resistance RL, and a filter capacitor C. The LC-type filter is connected to a DC-side voltage source U. dc Between the power grid and the grid, it is used to smooth DC voltage fluctuations and reduce harmonic components; Equivalent inductance L g and equivalent resistance R g It is connected between the output of the LC filter and the power grid; A converter is used to convert DC voltage to AC voltage and output three-phase current i. sk (k = a, b, c), where i sk These represent the output currents of phases A, B, and C, respectively. Grid connection point current measuring device, used to measure grid connection point current i k ; Filter capacitor voltage measuring device, used to measure filter capacitor voltage e ok (k = a, b, c), where e ok These represent the filter capacitor voltages for phases A, B, and C, respectively. Control unit, used to receive filter capacitor voltage e ok , grid connection point current i k and grid voltage u k The signal is processed, and a dual closed-loop control strategy combining current loop control and voltage loop control is adopted to achieve voltage stability control and power factor correction of the power grid.

4. The power coupling analysis method for grid-type converters based on dynamic gain matrix according to claim 3, characterized in that, The control unit includes: The power calculation module is used to calculate or monitor the output power of grid-connected power generation units. The virtual impedance control module is used to improve the stability and dynamic response characteristics of the power grid by adjusting the parameters of the virtual impedance.

5. The power coupling analysis method for grid-type converters based on dynamic gain matrix according to claim 2, characterized in that, The control system circuit passes through: The active loop APL generates the reference frequency and phase; The reactive power loop RPL generates the reference voltage amplitude; The converter modulation wave reference signal is generated by tracking reference values ​​through a dual closed-loop system of voltage and current, and is expressed by the following formula: In the formula: T set P set Q set These are the reference mechanical torque, reference mechanical power, and reference reactive power, respectively. T e P e Q e These are electromagnetic torque, electromagnetic power, and reactive power, respectively. Among them, P set =T set / ω,ω=dθ / dt; J p D p J q D q These are the active and reactive inertia coefficients and the damping coefficient, respectively. ω0 and ω are the rated angular frequency and the output angular frequency, respectively.

6. The power coupling analysis method for grid-type converters based on dynamic gain matrix according to claim 3 or 5, characterized in that, When the grid-type converter is used as a controllable voltage source, the output voltage and output current of the GFM are... The relationship between them is: In the formula, ω0 is the operating frequency of the GFM, and X g =ω0L g Transforming to the frequency domain yields: The complex power output of the converter is expressed as: Substituting equation (2) into equation (3) and performing a Laplace transform, we obtain the power expression for the output voltage amplitude and power angle of the GFM: Linearizing equation (4) at the steady-state operating point, we obtain the power small-signal model as follows: The elements of matrix G(s) are represented as follows: In the formula, ΔP, ΔQ, Δδ and ΔE are the small perturbation components of active power, reactive power, power angle and virtual internal potential, respectively.

7. The power coupling analysis method for grid-type converters based on dynamic gain matrix according to claim 6, characterized in that, In the analysis of the power coupling characteristics of the GFM, a two-input two-output coupling system is used for power coupling small-signal control. The two-input two-output coupling system is represented as follows: Y(s)=G(s)U(s) (8) In the formula, G(s) is the coupling transfer function matrix in equation (7), and U(s) and Y(s) are the two-dimensional input and output column vectors, respectively, where: From G(s) in equation (6), the amplitude-frequency response matrix is ​​obtained as follows: From equation (10), each element is a function of angular frequency, reflecting the frequency domain dynamic characteristics of parameter changes. The formula for solving the dynamic relative gain from the amplitude-frequency characteristics is: Where: DRGA(ω) is the dynamic gain matrix of the system. This represents the Hadamard product, which is the element-wise multiplication of matrices.

8. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the power coupling analysis method for grid-type converters based on dynamic gain matrix as described in any one of claims 1 to 7.

9. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the power coupling analysis method for grid-type converters based on dynamic gain matrix as described in any one of claims 1 to 7.

10. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by the processor, it implements the power coupling analysis method for grid-type converters based on dynamic gain matrix as described in any one of claims 1 to 7.

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