Dynamic gain matrix-based power coupling analysis method for network-constructing type converter

Abstract

The invention provides a dynamic gain matrix-based power coupling analysis method for a network-constructing type converter. The method comprises the following steps of: S1, constructing a dynamic analysis model of a GFM (Gradient Frequency Modulation) based on a power coupling mechanism; s2, a dynamic relative gain matrix DRGA is adopted as an analysis tool, and coupling characteristic analysis is conducted on the 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 on the analysis of the GFM power coupling characteristics through simulation analysis. According to the dynamic gain matrix-based network construction type converter power coupling analysis method provided by the invention, the coupling characteristics in the dynamic process of the system are analyzed by adopting the dynamic relative gain matrix, so that the accuracy and the effectiveness of the dynamic relative gain matrix are improved; compared with a traditional analysis method, the method has the advantages that the GFM power coupling relation can be reflected more accurately, the power coupling degree under different conditions is quantified, and the accuracy in the GFM power coupling analysis process is obviously improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power grid control, and in particular to a power coupling analysis method for a grid-type converter based on a dynamic gain matrix. Background Art

[0002] Under the background of implementing the "dual carbon" goal and building a new power system, new energy power generation represented by photovoltaic and wind power is the current development focus. Photovoltaic and wind power are connected to the power grid through power electronic equipment to provide necessary inertia support and damping support, making the power grid highly power electronic, and the overall low inertia and weak damping of the power system have appeared. GFM can effectively simulate the inertia and damping characteristics of synchronous generators (SG), and can provide a certain inertia support to the power grid, so that the inverter-type new energy units have good frequency, voltage support and regulation. On the other hand, the new energy power system has impedance equivalent grid-connected lines, and the complex application scenarios of power angles with large range changes cause GFM power coupling, which cannot guarantee the independent control of active and reactive loops, and has become one of the important factors affecting the interaction stability between GFM and the power grid.

[0003] For example, the publication number is CN202311475148. A grid-type converter analyzes the low-frequency oscillation of the power system and the system. Two low-frequency oscillation analysis models of the power system based on the grid-type converter are established, and the damping torque analytical expression of the system is derived. The influence of the control parameters of the grid-type 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 show a trend of increasing first and then decreasing, and the change of the grid-connected position and power proportion of new energy will also make the damping torque of the system increase first and then decrease, that is, there are optimal grid-type converter control parameters and grid-connected position and power proportion of new energy to maximize the low-frequency oscillation damping of the system. It realizes the accurate analysis of the low-frequency oscillation of the power system connected to the grid by the grid-type converter in many aspects, and provides a reference for the stability research of large-scale new energy connected to the grid by the grid-type converter.

[0004] Based on the above-mentioned existing technical solutions, the equivalent impedance of the transmission line from the converter output voltage to the grid connection point voltage is assumed to be purely inductive, and the GFM power coupling characteristics are analyzed. However, low-voltage lines often show resistance-inductive characteristics, and GFM has serious power coupling. Alternatively, the power coupling of GFM is analyzed at the steady-state operating point for the power angle and impedance ratio, but the power angle value at the steady-state operating point of GFM is usually large, which does not meet the constraints of the small power angle approximation. Summary of the invention

[0005] The present invention provides a grid-type converter power coupling analysis method based on a dynamic gain matrix, so as to solve the defect that the GFM power coupling characteristic analysis result in the prior art is inaccurate.

[0006] On the one hand, the present invention provides a method for analyzing power coupling of a grid-type converter based on a dynamic gain matrix, comprising:

[0007] S1. Construct a dynamic analysis model of GFM based on the power coupling mechanism;

[0008] S2. Using the dynamic relative gain matrix DRGA as an analysis tool, a coupling characteristic analysis is performed on the system dynamic process in the dynamic analysis model;

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

[0010] in:

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

[0012] S11. Analyze the power transmission characteristics of GFM under high power angle conditions;

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

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

[0015] When using the dynamic relative gain matrix for coupling characteristic analysis, it includes:

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

[0017] S22. Analyze the changes of dynamic relative gain matrix over time to reveal the evolution law of coupling characteristics in the dynamic process of the system;

[0018] When establishing the GFM grid-connected model, it includes:

[0019] S31. Construct the topology of the GFM grid-connected system;

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

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

[0022] According to a grid-type converter power coupling analysis method based on a dynamic gain matrix provided by the present invention, the dynamic analysis model includes a GFM main circuit and a control system circuit;

[0023] Wherein, the GFM main circuit is used to monitor and control the current and voltage signals in real time and transmit them to the control system circuit;

[0024] The control system circuit is used to realize the conversion and control of electric energy through the electronic components in the GFM main circuit, and specifically includes:

[0025] The control system circuit generates a control signal based on the input reference signal and feedback signal, and converts and controls electric energy through the electronic components in the main circuit structure according to the control signal. At the same time, sensors and other components in the main circuit structure will also feed back real-time voltage, current and other signals to the power control loop for precise control and adjustment.

[0026] According to a method for analyzing power coupling of a grid-type converter based on a dynamic gain matrix provided by the present invention, the GFM main circuit comprises:

[0027] DC side voltage source V dc , used to provide a stable DC voltage input, including a positive pole and a negative pole, used to receive electrical energy provided by a DC power source;

[0028] The AC output terminal includes three-phase live wires (phase A, phase B, phase C) and a neutral wire, which is used to provide AC power to the power grid or other loads;

[0029] Equivalent inductance L g And the equivalent resistance R g , which represent the electrical characteristics of the transmission line between the converter output voltage and the grid connection point voltage, and are connected between the output end of the LC filter and the grid;

[0030] The inverter is used to convert DC voltage into AC voltage and output three-phase current i sk (k=a,b,c), where i sk Represent the output current of phase A, phase B and phase C respectively. The converter is connected to the DC side voltage source V dc Between the AC output terminal, the converter consists of multiple switching devices, which realize the conversion of electric energy through pulse width modulation (PWM) or other equivalent control strategies;

[0031] The LC filter comprises a filter inductor L, a filter parasitic resistor RL and a filter capacitor C. The LC filter is connected to a DC voltage source U dc Between the power grid, it is used to smooth the DC voltage fluctuation and reduce the harmonic components, and is connected between the output end of the converter module and the AC output end;

[0032] The grid-connected point current measuring device is respectively connected to the DC input terminal, the AC output terminal and the converter module, and is used to measure the grid-connected point current ik;

[0033] Filter capacitor voltage measuring device, used to measure the filter capacitor voltage e ok (k=a,b,c), where e ok Represent the filter capacitor voltages of phase A, phase B, and phase C respectively;

[0034] The grid-connected point current measuring device and the filter capacitor voltage measuring device include a voltage sensor, a current sensor, a temperature sensor, and overcurrent protector and overvoltage protector elements.

[0035] A control unit for receiving a filter capacitor voltage e ok , grid-connected point current i k And the grid voltage u k signal, and adopts a dual closed-loop control strategy combining current loop control and voltage loop control to achieve voltage stability control and power factor correction of the power grid. By real-time monitoring and control of current and voltage signals, the stable operation and efficient power generation of the grid-connected power generation unit are ensured.

[0036] According to a method for analyzing power coupling of a grid-type converter based on a dynamic gain matrix provided by the present invention, the control unit includes:

[0037] A power calculation module, used to calculate or monitor the output power of the grid-connected power generation unit;

[0038] 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.

[0039] According to a method for analyzing power coupling of a grid-type converter based on a dynamic gain matrix provided by the present invention, the control system circuit is:

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

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

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

[0043]

[0044] Where:

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

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

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

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

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

[0050] According to a power coupling analysis method of a grid-type converter based on a dynamic gain matrix provided by the present invention, an internal voltage and current double closed-loop control loop is set to ensure the follow-up effect of the double-loop control. GFM can be equivalent to a controllable voltage source. When the grid-type converter is used as a controllable voltage source, the output voltage and output current of GFM are The relationship between them is:

[0051]

[0052] Where ω0 is the operating frequency of GFM, and X g =ω0L g , transformed into the frequency domain, we get:

[0053]

[0054] The complex power output of the converter is expressed as:

[0055]

[0056] Substituting (2) into (3) and performing Laplace transform, we can obtain the power expression of the GFM output voltage amplitude and power angle:

[0057]

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

[0059]

[0060] The elements in the matrix G(s) are expressed as:

[0061]

[0062] Where ΔP, ΔQ, Δδ and ΔE are the small disturbance components of active power, reactive power, power angle and virtual internal potential, respectively.

[0063] According to a power coupling analysis method for a grid-type converter based on a dynamic gain matrix provided by the present invention, the active power and reactive power output by the GFM are controlled by both the power angle and the voltage amplitude, and the dynamic processes are coupled with each other. 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 analyzing the power coupling characteristics of the GFM, a two-input two-output coupling system is used for power coupling small signal control, and the two-input two-output coupling system is expressed as:

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

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

[0066]

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

[0068]

[0069] From formula (10), each element is a function of the 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:

[0070]

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

[0072] On the other hand, the present invention also provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, it implements a power coupling analysis method for a grid-type converter based on a dynamic gain matrix as described in any one of the above.

[0073] On the other hand, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements any of the above-described methods for analyzing power coupling of a grid-type converter based on a dynamic gain matrix.

[0074] On the other hand, the present invention also provides a computer program product, including a computer program, which, when executed by a processor, implements any of the above-mentioned methods for analyzing power coupling of a grid-type converter based on a dynamic gain matrix.

[0075] The power coupling analysis method of a grid-type converter based on a dynamic gain matrix provided by the present invention adopts a dynamic relative gain matrix to analyze the coupling characteristics of the system in a dynamic process. Compared with traditional analysis methods, it can more accurately reflect the GFM power coupling relationship, quantify the degree of power coupling under different conditions, and significantly improve the accuracy of the GFM power coupling analysis process.

[0076] The present invention verifies the influence of line impedance ratio on converter power coupling characteristics and reactive power control deviation through simulation. These results can directly guide the operation and control of actual power systems and help 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 converters has become increasingly prominent. The invention 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 THE DRAWINGS

[0078] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0079] Figure 1 It is a flow chart of a method for analyzing power coupling of a grid-type converter based on a dynamic gain matrix provided in an embodiment of the present invention;

[0080] Figure 2 It is a typical GFM grid-connected system topology structure of the grid-connected converter power coupling analysis method based on the dynamic gain matrix provided in the embodiment of the present invention;

[0081] Figure 3 It is a schematic diagram of a GFM power control loop of a grid-type converter power coupling analysis method based on a dynamic gain matrix provided in an embodiment of the present invention;

[0082] Figure 4 It is a GFM grid-connected equivalent diagram of a grid-connected converter power coupling analysis method based on a dynamic gain matrix provided in an embodiment of the present invention;

[0083] Figure 5It is a power coupling small signal control block diagram of a grid-type control of a grid-type converter power coupling analysis method based on a dynamic gain matrix provided in an embodiment of the present invention;

[0084] Figure 6 : is a graph showing the change in impedance ratio and the number of RGAs of the system when the power angle changes according to the power coupling analysis method of the grid-type converter based on the dynamic gain matrix provided by the embodiment of the present invention, wherein Figure 6 (a) is the change diagram of the system RGA number when the impedance ratio changes. Figure 6 (b) is the change diagram of the system RGA number when the power angle changes;

[0085] Figure 7 is a simulation result diagram of a power coupling analysis method for a grid-type converter based on a dynamic gain matrix under different impedance ratios provided by an embodiment of the present invention, wherein: Figure 7 (a) is the power angle diagram under different impedance ratios. Figure 7 (b) is the active power diagram under different impedance ratios. Figure 7 (c) is the reactive power diagram under different impedance ratios;

[0086] Figure 8 It is a schematic diagram of the structure of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0087] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0088] Combine the following Figure 1-Figure 6 Describe the power coupling analysis method of the grid-type converter based on the dynamic gain matrix of the present invention;

[0089] Figure 1 It is a flow chart of a method for analyzing power coupling of a grid-type converter based on a dynamic gain matrix provided in an embodiment of the present invention.

[0090] like Figure 1 As shown, the grid-type converter power coupling analysis method based on the dynamic gain matrix provided in the embodiment of the present invention can be executed by a host computer, and the method mainly includes the following steps:

[0091] S1. Construct a dynamic analysis model of GFM based on the power coupling mechanism;

[0092] S2. Using the dynamic relative gain matrix DRGA as an analysis tool, a coupling characteristic analysis is performed on the system dynamic process in the dynamic analysis model;

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

[0094] in:

[0095] When constructing the dynamic analysis model of GFM based on the power coupling mechanism, it includes:

[0096] S11. Analyze the power transmission characteristics of GFM under high power angle conditions;

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

[0098] S13, construct a mathematical model that can reflect the dynamic behavior and power coupling relationship of GFM;

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

[0100] Wherein, the GFM main circuit is used to monitor and control the current and voltage signals in real time and transmit them to the control system circuit;

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

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

[0103] Among them: Figure 2 As shown, Figure 2 It is the GFM main circuit structure. The GFM main circuit includes:

[0104] DC side voltage source V dc , used to provide a stable DC voltage input, including a positive pole and a negative pole, used to receive electrical energy provided by a DC power source;

[0105] The AC output terminal includes three-phase live wires (phase A, phase B, phase C) and a neutral wire, which is used to provide AC power to the power grid or other loads;

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

[0107] The inverter is used to convert DC voltage into AC voltage and output three-phase current i sk (k=a,b,c), where i sk Represent the output current of phase A, phase B and phase C respectively. The converter is connected to the DC side voltage source V dc Between the AC output terminal, the converter consists of multiple switching devices, which realize the conversion of electric energy through pulse width modulation (PWM) or other equivalent control strategies;

[0108] The LC filter comprises a filter inductor L, a filter parasitic resistor RL and a filter capacitor C. The LC filter is connected to a DC voltage source U dc Between the power grid, it is used to smooth the DC voltage fluctuation and reduce the harmonic components, and is connected between the output end of the converter module and the AC output end;

[0109] The grid-connected point current measuring device is respectively connected to the DC input terminal, the AC output terminal and the converter module, and is used to measure the grid-connected point current ik;

[0110] Filter capacitor voltage measuring device, used to measure the filter capacitor voltage e ok (k=a,b,c), where e ok Represent the filter capacitor voltages of phase A, phase B, and phase C respectively;

[0111] The grid-connected point current measuring device and the filter capacitor voltage measuring device include a voltage sensor, a current sensor, a temperature sensor, and overcurrent protector and overvoltage protector elements.

[0112] A control unit for receiving the filter capacitor voltage e ok , grid-connected point current i k And the grid voltage u k The dual closed-loop control strategy combining current loop control and voltage loop control is adopted to realize voltage stability control and power factor correction of the power grid. The stable operation and efficient power generation of the grid-connected power generation unit are ensured by real-time monitoring and control of current and voltage signals.

[0113] More specifically, the control unit includes:

[0114] A power calculation module, used to calculate or monitor the output power of the grid-connected power generation unit;

[0115] A virtual impedance control module, used to improve the stability and dynamic response characteristics of the power grid by adjusting the parameters of the virtual impedance;

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

[0117]

[0118] Where, 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 the active and reactive inertia coefficients and damping coefficients respectively; ω0 and ω are the rated angular frequency and output angular frequency respectively.

[0119] GFM Small Signal Modeling Energy Storage

[0120] By setting up an internal voltage and current dual closed-loop control loop, the following effect of the dual-loop control is guaranteed. GFM can be equivalent to a controllable voltage source. The equivalent circuit is as follows: Figure 4 As shown, according to Figure 4 , GFM output voltage and output current The relationship between them is:

[0121]

[0122] Where ω0 is the operating frequency of GFM, and X g =ω0L g . Transformed to the frequency domain, we get:

[0123]

[0124] The complex power output of the converter is expressed as:

[0125]

[0126] Substituting (2) into (3) and performing Laplace transform, we can obtain the power expression of the GFM output voltage amplitude and power angle:

[0127]

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

[0129]

[0130] The elements in the matrix G(s) are expressed as:

[0131]

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

[0133] Analysis of GFM power coupling characteristics

[0134] The active power and reactive power output by GFM are controlled by both the power angle and the voltage amplitude, and the dynamic processes are coupled with each other. 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. The power small signal model considering the coupling characteristics is as follows: Figure 5 shown.

[0135] for Figure 5 The two-input and two-output coupled system described by can be expressed as:

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

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

[0138]

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

[0140]

[0141] From formula (10), each element is a function of the 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:

[0142]

[0143] Where: DRGA(ω) is the dynamic relative gain array of the system, Represents the Hadamard product, which is the multiplication of corresponding matrix elements.

[0144] Based on the above theoretical analysis, we can establish Figure 5Dynamic relative gain matrix of the system. Since dynamic relative gain is the generalization of static relative gain in the full frequency domain, it has the basic properties of static relative gain. Like static relative gain, dynamic relative gain also has the same rules:

[0145] DRGA11(ω)+DRGA12(ω)=1

[0146] DRGA11(ω)=DRGA22(ω)

[0147] DRGA12(ω)=DRGA21(ω)

[0148] Analogous to the static relative gain theory, the larger the dynamic relative gain value, the stronger the control effect of the input corresponding to the dynamic relative gain on the output, and the smaller the coupling effect of the control loop on other control loops. The size of DRGA (ω) directly reflects the degree of coupling of the system. When the value of DRGA (ω) is close to 0, the coupling effect of the system can be ignored. When DRGA (ω) is larger, the coupling becomes more serious. In order to make an intuitive comparison of the degree of DRGA coupling, the RGA number is introduced for quantitative analysis. By definition, the smaller the RGA number, the lower the coupling of the system.

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

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

[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 resonance peak, the deeper the active and reactive coupling of the system near this frequency band during the dynamic process. Figure 6 (b) It can be seen that as the power angle δ increases, the resonant frequency is also around 314rad / s (example). The larger the resonance peak, the lower the system coupling degree as the impedance ratio increases. Analysis shows that the power coupling degree of GFM is related to the power angle and line impedance ratio. As the power angle increases or the impedance ratio decreases, the power coupling degree of the converter continues to deepen. Finally, simulation verifies that when the line impedance ratio R / X increases, the power angle δ becomes larger and the reactive power control deviates significantly.

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

[0153] Application Areas

[0154] Renewable energy grid connection: In the grid-connected power generation system of wind energy, solar energy and other renewable energy, the grid-connected converter is the key equipment to connect the renewable energy and the power grid. The present invention can help analyze the power coupling characteristics between converters when renewable energy is connected to the grid, optimize the grid connection control strategy, and improve the stability and efficiency of renewable energy grid connection.

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

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

[0157] Experimental example

[0158] Based on the above embodiment scheme, the present invention uses MATLAB / Simulink software to build Figure 1 The energy storage VSC simulation model shown in the figure has main simulation parameters as shown in Table 1:

[0159] Table 1GFM grid-connected simulation parameters

[0160]

[0161] like Figure 7 As shown in the figure, in the initial state, GFM stably feeds 150kW of active power to the grid. When t is set at 2s, the active power reference value increases by 150kW; Figure 7 As shown in (a), as the line impedance ratio decreases, the power angle gradually increases; Figure 7 As shown in (b), as the line impedance ratio decreases, the active power does not change significantly; Figure 7 As shown in (c), as the line impedance ratio decreases, the reactive output increases significantly and the coupling degree increases significantly.

[0162] Figure 8 It is a schematic diagram of the structure of an electronic device provided by an embodiment of the present invention.

[0163] like Figure 8As shown, the electronic device may include: a processor 610, a communication interface 620, a memory 630 and a communication bus 640, wherein the processor 610, the communication interface 620 and the memory 630 communicate with each other through the communication bus 640. The processor 610 may call the logic instructions in the memory 630 to execute a power coupling analysis method for a grid-type converter based on a dynamic gain matrix, the method comprising:

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

[0165] S2. Using the dynamic relative gain matrix DRGA as an analysis tool, a coupling characteristic analysis is performed on the system dynamic process in the dynamic analysis model;

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

[0167] In addition, the logic instructions in the above-mentioned memory 630 can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when it is sold or used as an independent product. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0168] On the other hand, the present invention further provides a computer program product, the computer program product includes a computer program, the computer program can be stored in a non-transitory computer-readable storage medium, when the computer program is executed by a processor, the computer can execute the grid-type converter power coupling analysis method based on the dynamic gain matrix provided by the above methods, the method includes: S1, constructing a dynamic analysis model of GFM based on the power coupling mechanism;

[0169] S2. Using the dynamic relative gain matrix DRGA as an analysis tool, a coupling characteristic analysis is performed on the system dynamic process in the dynamic analysis model;

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

[0171] In another aspect, the present invention further provides a non-transitory computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the method for analyzing power coupling of a grid-type converter based on a dynamic gain matrix provided by the above methods is implemented, and the method comprises: S1, constructing a dynamic analysis model of GFM based on a power coupling mechanism;

[0172] S2. Using the dynamic relative gain matrix DRGA as an analysis tool, a coupling characteristic analysis is performed on the system dynamic process in the dynamic analysis model;

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

[0174] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0175] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for analyzing power coupling of a grid-type converter based on a dynamic gain matrix, 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, a coupling characteristic analysis is performed on the system dynamic process in the dynamic analysis model; S3, establishing a GFM grid-connected model, and verifying the correctness and effectiveness of the dynamic relative gain matrix in analyzing the GFM power coupling characteristics through simulation analysis; in: When constructing the dynamic analysis model of GFM based on the power coupling mechanism, it includes: S11. Analyze the power transmission characteristics of GFM under high power angle conditions; S12, obtaining the influence 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, it includes: 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 changes of dynamic relative gain matrix over time to reveal the evolution law of coupling characteristics in the dynamic process of the system; When establishing the GFM grid-connected model, it includes: S31. Construct the topology structure of the GFM grid-connected system; S32, setting parameters of the GFM and the power grid, including power, voltage, current and impedance; Based on the topology and parameters, a simulation model is constructed to simulate the operation of the GFM grid-connected system.

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

3. The method for analyzing power coupling of a grid-type converter based on a dynamic gain matrix according to claim 2, characterized in that: The GFM main circuit comprises: DC side voltage source V dc , used to provide stable DC voltage input; The LC filter comprises a filter inductor L, a filter parasitic resistor RL and a filter capacitor C. The LC filter is connected to a DC voltage source U dc Between the power grid, it is used to smooth the DC voltage fluctuation and reduce the harmonic components; Equivalent inductance L g And the equivalent resistance R g , connected between the output end of the LC filter and the power grid; The inverter is used to convert DC voltage into AC voltage and output three-phase current i sk (k=a,b,c), where i sk Represent the output current of phase A, phase B and phase C respectively; Grid point current measuring device, used to measure the grid point current i k ; Filter capacitor voltage measuring device, used to measure the filter capacitor voltage e ok (k=a,b,c), where e ok Represent the filter capacitor voltages of phase A, phase B, and phase C respectively; A control unit for receiving a filter capacitor voltage e ok , grid-connected point current i k And the grid voltage u k The signal is received by the power grid, 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 method for analyzing power coupling of a grid-type converter based on a dynamic gain matrix according to claim 3 is characterized in that: The control unit comprises: A power calculation module, used to calculate or monitor the output power of the grid-connected power generation unit; 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 method for analyzing power coupling of a grid-type converter based on a dynamic gain matrix according to claim 2, characterized in that: The control system circuit is as follows: The active loop APL generates reference frequency and phase; The reactive loop RPL generates a reference voltage amplitude; The reference value of the converter modulation wave is generated by tracking the voltage and current double closed loop reference value, which is expressed by the following formula: Where: T set , P set , Q set They are reference mechanical torque, reference mechanical power and reference reactive power respectively; T e , P e , Q e They 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 are active and reactive inertia coefficients and damping coefficients respectively; ω0 and ω are the rated angular frequency and output angular frequency respectively.

6. The method for analyzing power coupling of a grid-type converter based on a 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 GFM output voltage and output current The relationship between them is: Where ω0 is the operating frequency of GFM, and X g =ω0L g , transformed into the frequency domain, we get: The complex power output of the converter is expressed as: Substituting (2) into (3) and performing Laplace transform, we can obtain the power expression of the GFM output voltage amplitude and power angle: Linearizing equation (4) at the steady-state operating point, we get the power small signal model: The elements in the matrix G(s) are expressed as: Where ΔP, ΔQ, Δδ and ΔE are the small disturbance components of active power, reactive power, power angle and virtual internal potential, respectively.

7. The method for analyzing power coupling of a grid-type converter based on a dynamic gain matrix according to claim 6, characterized in that: When analyzing the GFM power coupling characteristics, a two-input two-output coupling system is used to perform power coupling small signal control. The two-input two-output coupling system is expressed as: Y(s)=G(s)U(s) (8) Where G(s) is the coupling transfer function matrix in equation (7), U(s) and Y(s) are the two-dimensional input and output column vectors, respectively. The amplitude-frequency characteristic matrix obtained from G(s) in equation (6) is: From formula (10), each element is a function of the 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, Represents the Hadamard product, which is the multiplication of corresponding matrix elements.

8. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the power coupling analysis method of the grid-type converter based on the dynamic gain matrix as described in any one of claims 1 to 7 is implemented.

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

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

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