A parameter setting method and system for large-scale grid connection of a network-forming inverter

Abstract

The present invention discloses a method and system for parameter setting of large-scale grid connection of network-forming inverters, belonging to the technical field of new energy grid connection. Using a single physical unit, the access conditions of units with different controls at different locations are simulated by continuously changing the line parameters and control parameters in sequence. It is connected to the digital aggregation bus through a physical-digital interface, parameter setting is carried out, and a digital simulation unit group is correspondingly established, so that the external performance characteristics of each unit are consistent. Finally, the parameters of the tested physical unit are exported to the real grid-connected unit for grid connection. The parameter setting method in this method not only ensures that the external environment of the physical unit is similar to that of the real unit when it is connected, gives highly credible results when realizing large-scale grid connection pre-testing, but also reduces the cost and threshold of physical unit testing.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy grid connection, and more specifically, relates to a parameter setting method and system for large-scale grid connection of grid-forming inverters. Background Art

[0002] The current international energy security situation is severe, demanding an accelerated clean and low-carbon transformation of energy. For weak power grids in the "desert, gobi, and wasteland" areas lacking large-scale conventional thermal and hydro power sources for local support, grid-forming devices are widely favored due to their ability to independently construct voltage phases. Different from the current source following control of grid-following devices, grid-forming devices are voltage sources that independently build voltage and frequency. When connected in large numbers, they face the problems of voltage source parallel connection, pre-synchronization, and commissioning. When engineers face the connection and commissioning of a large number of grid-forming devices, they often require a lot of time to cut off the power for device testing, which is very time-consuming. The present invention aims to provide a low-cost and efficient commissioning method and system for large-scale connection of grid-forming devices. Summary of the Invention

[0003] To solve the deficiencies in the prior art, the present invention provides a parameter setting method and system for large-scale grid connection of grid-forming inverters. By digitally constructing a single physical unit and modifying different line impedances and control parameters of each voltage loop and current loop, a more accurate model corresponding to the physical unit is established. The present invention aims to provide a platform for grid connection testing of single or multiple physical units, ensuring that the access environment is consistent between the digital side and the physical side when real units are connected to the grid, and enabling pre-tests and parameter corrections for large-scale grid connection of inverters in advance, improving the grid connection efficiency, and reducing the threshold and cost of physical testing.

[0004] The present invention adopts the following technical solutions. The first aspect of the present invention provides a parameter setting method for large-scale grid connection of grid-forming inverters, including the following steps:

[0005] Step 1: Establish a virtual-real fusion topology structure including a digital simulation model and a physical unit; the digital simulation model is used to simulate the grid connection topology structure of a new energy grid-forming station;

[0006] Step 2: According to the set order of each physical unit, give the parameters of the physical unit to be pre-tested for grid connection to the physical unit, connect the physical unit that has obtained the parameters of the physical unit to the digital simulation model, and after the physical unit is debugged stably, save the current operation control parameters of the physical unit as the control parameters of the physical unit to the storage medium;

[0007] Step 3: Disconnect the physical unit from the digital simulation model, and establish a digital simulation unit in the digital simulation model that is consistent with the external characteristics of the physical unit. Keep the digital simulation unit connected to the grid in the digital simulation model to complete the grid connection pre-test for one physical unit.

[0008] Step 4: Determine whether the grid connection pre-tests for all physical units have been completed. If not, return to Step 2 to conduct the grid connection pre-test for the next physical unit. If completed, execute Step 5.

[0009] Step 5: Export the control parameters saved in the storage medium to the corresponding physical units.

[0010] Preferably, the virtual-real fusion topology structure includes: a physical unit module, a physical-digital interface module, and a digital simulation model. The physical unit module is connected to the digital simulation model through the physical-digital interface module.

[0011] The physical unit module includes: a physical unit measurement unit, branch A1. Branch A1 includes a physical unit VSG #A1, an adjustable impedance unit, and a physical unit switch unit SW connected in sequence. A1 ; The physical unit measurement unit is respectively connected to the adjustable impedance unit and the physical unit switch unit SW. A1 The physical unit VSG #A1 includes: a first DC bus power supply interface, a first grid-connected inverter, and a first inverter controller. The first DC bus power supply interface is connected to the input end of the first grid-connected inverter. The output end of the first grid-connected inverter is connected to the physical-digital interface module through the physical unit switch unit SW. A1 The first inverter controller is connected to the first grid-connected inverter.

[0012] The digital simulation model includes: a digital unit module, a collection bus module, and a power grid module. The digital unit module is connected to the power grid module through the collection bus module. The physical-digital interface module is connected to the collection bus module.

[0013] Preferably, the digital unit module includes: N D digital simulation units VSG #Bi, i = 1, 2, ···, N. D Each digital simulation unit VSG #Bi is connected to the collection bus module through a digital simulation impedance unit Z Bi and a digital simulation switch unit SW Bi to form multiple branches i connected to the collection bus module. Each branch i is provided with a digital simulation unit measurement unit i.

[0014] The digital simulation unit VSG #Bi includes: a second DC bus power supply interface, a second grid-connected inverter, and a second inverter controller. The second DC bus power supply interface is connected to the input end of the second grid-connected inverter, and the output end of the second grid-connected inverter is connected to the aggregated bus module via a digital simulation impedance unit Z Bi and a digital simulation switch unit SW Bi ; The second inverter controller includes a delay / lead link and is connected to the second grid-connected inverter.

[0015] Preferably, step 2 includes:

[0016] Assign a serial number to the grid connection pre-test according to the physical unit number of the physical unit to be grid-connected for pre-test;

[0017] After the parameters of the physical unit VSG #Ci are given to the physical unit VSG #A1, close the physical unit switch unit SW A1 , so as to connect the physical unit VSG #A1 to the digital simulation model via the physical-digital interface module, where i = 1, 2, ···, N C ; After the physical unit VSG #A1 reaches stable operation after debugging, measure the electrical quantities of branch A1 with the physical unit measurement unit to obtain the first electrical quantities of branch A1. The first electrical quantities include voltage, current, and phase angle, and output the first electrical quantities to the aggregated bus module of the digital simulation model to save its waveform f A1 (t) to the storage medium;

[0018] Save the current operating control parameters of the physical unit VSG #A1 as the control parameters of the replaced physical unit VSG #Ci to the storage medium.

[0019] Preferably, step 3 includes:

[0020] Disconnect the physical unit VSG #A1, and model the digital simulation unit VSG #Bi in the digital simulation model according to the current operating control parameters of the physical unit VSG #A1 to obtain the digital simulation unit VSG #Bi to be connected;

[0021] Close the digital simulation switch unit SW Bi , so as to connect the digital simulation unit VSG #Bi. Use the digital simulation unit measurement unit i and the bus measurement unit to measure the electrical quantities on branch i and the aggregated bus respectively to obtain the second electrical quantities for multiple cycles, and obtain the waveform f according to the second electrical quantities for multiple cycles B1 (t), and the number of cycles is the same as that of the waveform f A1 (t);

[0022] Determine whether the external characteristics of the physical unit VSG #A1 and the digital simulation unit VSG #Bi are consistent. If they are consistent, execute Step 4; if not, adjust the control parameters of the digital simulation unit VSG #Bi until the external characteristics of the physical unit VSG #A1 and the digital simulation unit VSG #Bi are consistent. Then, update the corresponding control parameters stored in Step 2 with the adjusted control parameters of the digital simulation unit VSG #Bi and continue to execute Step 4.

[0023] Preferably, determining whether the external characteristics of the physical unit VSG #A1 and the digital simulation unit VSG #Bi are consistent includes:

[0024] Perform FFT processing on the waveforms f A1 (t) and f B1 (t) respectively to obtain the parameters of the fundamental wave quantity and harmonic wave quantity in the waveforms f A1 (t) and f B1 (t). Then, judge whether the waveforms f A1 (t) and f B1 (t) are consistent according to the parameters of the fundamental wave quantity and harmonic wave quantity in the waveforms f A1 (t) and f B1 (t).

[0025] Preferably, judging whether the waveforms f A1 (t) and f B1 (t) are consistent according to the parameters of the fundamental wave quantity and harmonic wave quantity in the waveforms f A1 (t) and f B1 (t) includes that if the amplitude difference, frequency difference, and phase difference of the fundamental wave quantity in the waveforms f A1 (t) and f B1 (t) are all less than the set value or ratio, then the fundamental wave quantities in the waveforms f A1 (t) and f B1 (t) are consistent;

[0026] When the amplitude difference, frequency difference, and phase difference of the corresponding frequency harmonic wave quantities in the waveforms f A1 (t) and f B1 (t) are less than the set value or ratio, then the harmonic wave quantities in the waveforms f A1 (t) and f B1 (t) are consistent;

[0027] If the fundamental wave quantity and harmonic wave quantity in the waveforms f A1 (t) and f B1 (t) are both consistent, then the external characteristics of the physical unit VSG #A1 and the digital simulation unit VSG #Bi are consistent.

[0028] Preferably, adjusting the parameters of the digital simulation unit VSG #Bi includes: the time t of the delay / lead linkd , adjust the proportional parameter K of the voltage control loop up , integral parameter K ui , proportional parameter K of the current loop control loop ip , integral parameter K ii and line impedance Z eq at least one of them.

[0029] The second aspect of the present invention provides a parameter tuning system for large-scale grid connection of grid-forming inverters, which is used to execute a parameter tuning method for large-scale grid connection of grid-forming inverters according to the first aspect, including: a physical unit module, a physical-digital interface module, and a digital simulation model. The physical unit module is connected to the digital simulation model through the physical-digital interface module;

[0030] The physical unit module includes: physical unit VSG #A1, adjustable impedance unit, physical unit measurement unit, and physical unit switch unit SW A1 ; physical unit VSG #A1, adjustable impedance unit, and physical unit switch unit SW A1 are connected in sequence to form branch A1; the physical unit measurement unit is used to measure the electrical quantities of branch A1;

[0031] The digital simulation model includes: a digital unit module, a collection bus module, and a power grid module.

[0032] Preferably, the physical-digital interface module includes: an active four-quadrant power amplifier and a digital simulation interface; the physical unit VSG #A1 outputs an analog AC signal through a grid-connected inverter, and after passing through the active four-quadrant power amplifier, the analog quantity is converted into a digital quantity and enters the digital simulation model.

[0033] Preferably, the physical unit VSG #A1 includes: a first DC bus power supply interface, a first grid-connected inverter, and a first inverter controller; the first DC bus power supply interface is a physical device, and the power sources include at least one of a wind turbine plus an upstream rectifier, a photovoltaic array, and a energy storage battery; the first DC bus power supply interface is connected to the input end of the first grid-connected inverter, and the output end of the first grid-connected inverter is connected to the physical-digital interface module through the physical unit switch unit SW A1 ; the first inverter controller is connected to the first grid-connected inverter.

[0034] Preferably, the digital unit module includes: N D digital simulation units, not less than the number of physical units to be connected to the grid. Each digital simulation unit is represented by VSG #Bi, i = 1, 2, ···, N D ; each digital simulation unit VSG #Bi passes through a digital simulation impedance unit Z Bi and a digital simulation switch unit SWBi Connect to the aggregated busbar module to form multiple branches i connected to the aggregated busbar module. Each branch i is provided with a digital simulation unit measurement unit i for measuring the electrical quantities of branch i.

[0035] The digital simulation unit VSG #Bi includes: a second DC bus power supply interface, a second grid-connected inverter, and a second inverter controller; the second DC bus power supply interface, the second grid-connected inverter, and the second inverter controller of the digital simulation unit VSG #Bi are simulation models; the second inverter controller includes: a delay / lead link for adjusting parameters to make the output of the physical unit VSG #A1 consistent with that of the digital simulation unit VSG #Bi.

[0036] Preferably, the aggregated busbar module includes: an aggregated busbar and a busbar measurement unit for measuring the electrical quantities of the busbar; each digital simulation unit VSG #Bi can be connected to the aggregated busbar as a branch.

[0037] The power grid module includes: a digital simulation power grid G1 and a power grid impedance Z g ; The aggregated busbar is connected to the digital simulation power grid G1 through the power grid impedance Z g ; Wherein, the digital simulation power grid G1 and the power grid impedance Z g are determined according to the parameters of the local grid connection.

[0038] The third aspect of the present invention provides an electronic device, including: a memory, a processor, and a computer program stored on the memory and executable on the processor. When the computer program is loaded into the processor, it implements a parameter setting method for large-scale grid connection of a network-forming inverter according to the first aspect.

[0039] The fourth aspect of the present invention provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, it implements a parameter setting method for large-scale grid connection of a network-forming inverter according to the first aspect.

[0040] Compared with the prior art, the beneficial effects of the present invention at least include:

[0041] 1. The present invention uses a single physical unit, and by continuously changing the line parameters and control parameters in sequence, it simulates the access of units with different controls at different locations, uses a physical-digital interface to access the digital aggregated busbar, performs parameter setting, and correspondingly establishes a digital simulation unit group, making the simulation model more in line with the actual situation, ensuring that when the physical unit accesses the digital simulation system, its access environment is consistent with the actual unit environment, with higher credibility, and the grid-connected inverter cluster provides active and stable support for the power grid;

[0042] 2. Greatly reduce the threshold and cost of physical unit experiments. Only one physical unit is required to complete the grid connection pre-test. Description of the Drawings

[0043] Figure 1 It is a flowchart of a parameter tuning method for large-scale grid connection of grid-forming inverters provided according to an embodiment of the present invention;

[0044] Figure 2 It is a schematic diagram of a virtual-real fusion topology structure involving a digital simulation model and a physical unit in the present invention;

[0045] Figure 3 It is a schematic diagram of the physical unit VSG #A1 in the embodiment involved in the present invention;

[0046] Figure 4 It is a schematic diagram of the physical-digital interface module in the embodiment involved in the present invention;

[0047] Figure 5 It is a schematic diagram of the digital simulation unit VSG #Bi in the embodiment involved in the present invention. Detailed Embodiments

[0048] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. The described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the spirit of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

[0049] The present invention provides a parameter tuning method for large-scale grid connection of grid-forming inverters. Using a single physical unit, by continuously changing the line parameters and control parameters in sequence, it is possible to simulate the access situations of units with different controls at different locations. Connect to the digital aggregation bus through a physical-digital interface, perform parameter tuning, and correspondingly establish a digital simulation unit group, so that the external performance characteristics of each unit are consistent. Finally, export the parameters of the tested physical unit to the real grid-connected unit for grid connection.

[0050] Specifically, as Figure 1 shown, Embodiment 1 of the present invention provides a parameter tuning method for large-scale grid connection of grid-forming inverters, including the following steps:

[0051] Step 1: Establish a virtual-real fusion topology structure including a digital simulation model and a physical unit; the digital simulation model is used to simulate the grid connection topology structure of a new energy grid-forming power station; the physical unit is used to successively replace the physical unit to be connected to the grid and access the digital simulation model, perform debugging, and establish corresponding digital simulation units in the digital simulation model.

[0052] Preferably but not limited thereto, step 1 specifically includes:

[0053] Step 1.1: Construct a virtual-real fusion topology structure, including: a physical unit module, a physical-digital interface module, and a digital simulation model. The physical unit module is connected to the digital simulation model through the physical-digital interface module.

[0054] Further preferably but not limited thereto, as Figure 2 shown, the physical unit module includes: a physical unit VSG #A1, an adjustable impedance unit, a physical unit measurement unit, and a physical unit switch unit SW A1 ; the physical unit VSG #A1, the adjustable impedance unit, and the physical unit switch unit SW A1 are connected in sequence to form branch A1; the physical unit measurement unit is used to measure the electrical quantities of branch A1.

[0055] As Figure 3 shown, the physical unit VSG #A1 includes: a first DC bus power supply interface, a first grid-connected inverter, and a first inverter controller; the first DC bus power supply interface is a physical device, and the power source is diverse, for example but not limited to, a fan plus a machine-side rectifier, a photovoltaic array, and a storage battery and other DC sources; the first DC bus power supply interface is connected to the input end of the first grid-connected inverter, and the output end of the first grid-connected inverter is connected to the physical-digital interface module through the physical unit switch unit SW A1 ; the first inverter controller is connected to the first grid-connected inverter.

[0056] Further preferably but not limited thereto, as Figure 4 shown, the physical-digital interface module includes: an active four-quadrant power amplifier and a digital simulation interface; the physical unit VSG #A1 outputs an analog AC signal through the first grid-connected inverter, and after passing through the active four-quadrant power amplifier, the analog quantity is converted into a digital quantity and enters the digital simulation model.

[0057] Further preferably but not limited thereto, as Figure 2 shown, the digital simulation model includes: a digital unit module, a converging bus module, and a power grid module; the digital unit module is connected to the power grid module through the converging bus module, and the physical-digital interface module is connected to the converging bus module.

[0058] The digital unit module includes: N D digital simulation units, not less than the number of physical units to be connected to the network; for example but not limited to, each digital simulation unit is represented by a digital simulation unit VSG #Bi, i = 1, 2, ···, N D , each digital simulation unit VSG#Bi passes through a digital simulation impedance unit Z Bi and a digital simulation switch unit SWBi Connected to the aggregated busbar module to form multiple branches i connected to the aggregated busbar module, and each branch i is provided with a digital simulation unit measuring unit i for measuring the electrical quantities of branch i.

[0059] As Figure 5 shown, the digital simulation unit VSG #Bi is structurally similar to the physical unit VSG #A1, and also includes: a second DC bus power supply interface, a second grid-connected inverter, and a second inverter controller; it can be understood that the second DC bus power supply interface, the second grid-connected inverter, and the second inverter controller of the digital simulation unit VSG #Bi are simulation models; it should be noted that, compared with the physical unit VSG #A1, the digital simulation unit VSG #Bi has an additional delay / lead link at the second inverter controller for parameter adjustment to make the output of the physical unit VSG #A1 consistent with that of the digital simulation unit VSG #Bi.

[0060] The aggregated busbar module includes: an aggregated busbar and a busbar measuring unit for measuring the electrical quantities of the busbar; each digital simulation unit VSG #Bi can be connected to the aggregated busbar as a branch.

[0061] The power grid module includes: a digital simulation power grid G1 and a power grid impedance Z g ; the aggregated busbar is connected to the digital simulation power grid G1 through the power grid impedance Z g ; among them, the digital simulation power grid G1 and the power grid impedance Z g are determined according to the parameters of the local grid connection.

[0062] Step 1.2: Obtain the parameters of N C physical units to be connected to the grid. For example, but not limited to, each physical unit to be connected to the grid is represented by a physical unit VSG #Ci, i = 1, 2, ···, N C , and the parameters of the physical unit VSG #Ci include: control parameters of the voltage-current loop / active-reactive loop, impedance magnitude and other related parameters.

[0063] Step 2: In the set order, give the parameters of a physical unit to be pre-tested for grid connection to the physical unit, and connect the physical unit to the digital simulation model. After the physical unit VSG #A1 is debugged and stabilized, save the current operating control parameters of the physical unit as the control parameters of the replaced physical unit to the storage medium.

[0064] Preferably but not restrictively, step 2 specifically includes:

[0065] Step 2.1: Assign a serial number to the grid connection pre-test according to the serial number of the physical unit to be pre-tested for grid connection. For example, if the current serial number of the physical unit to be pre-tested for grid connection is VSG #C1, then let i = 1 for subsequent establishment of the corresponding digital simulation unit VSG#B1.

[0066] Step 2.2: Give the VSG #Ci parameters of the physical unit to the physical unit VSG #A1, and close the physical unit switch unit SW A1 , connect the physical unit VSG #A1 to the digital simulation model through the physical-digital interface module; after the physical unit VSG #A1 reaches stable operation through debugging, measure the electrical quantities of branch A1 with the physical unit measurement unit to obtain the first electrical quantities of branch A1, and the first electrical quantities include: voltage, current and phase angle, and output the first electrical quantities to the collecting bus of the digital simulation model and save its waveform f A1 (t) to the storage medium, for example but not limited to, take 10 cycle quantities; measure the electrical quantities of the collecting bus module with the bus measurement unit to obtain the voltage, current and phase angle of the collecting bus.

[0067] For example but not limited to, when i = 1, give the VSG #C1 parameters of the physical unit to the physical unit VSG #A1, replace the physical unit VSG #C1 with the physical unit VSG #A1 and connect it to the digital simulation model, and obtain the electrical quantity data with the physical unit measurement unit.

[0068] The real-time feedback data of the electrical quantities of branch A1 and the collecting bus includes: frequency ω g , voltage amplitude U g , active power P g and reactive power Q g and other information, and generate the equivalent internal potential phase θ and amplitude E of the collecting bus respectively through the active control loop and the reactive control loop m .

[0069] Step 2.3: Save the current operating control parameters of the physical unit VSG #A1 as the control parameters of the replaced physical unit VSG #Ci to the storage medium.

[0070] Step 3: Disconnect the physical unit, and establish a digital simulation unit in the digital simulation model that is consistent with the external characteristics of the physical unit. This digital simulation unit realizes grid connection in the digital simulation model, that is, completes the grid connection pre-test of a physical unit.

[0071] Preferably but not restrictively, step 3 specifically includes:

[0072] Step 3.1: Disconnect the physical unit VSG #A1, and model the digital simulation unit VSG #Bi in the digital simulation model according to the current parameters of the physical unit VSG #A1 to obtain the digital simulation unit VSG #Bi to be connected. For example but not limited to, when i = 1, model the digital simulation unit VSG #B1 according to the current parameters of the physical unit VSG #A1.

[0073] Step 3.2: Close the digital simulation switch unit SW Bi , connect to the digital simulation unit VSG #Bi, use the digital simulation unit measurement unit i and the bus measurement unit to measure the electrical quantities on branch i and the busbar respectively, and obtain the second electrical quantities of multiple cycles. According to the second electrical quantities of multiple cycles, the waveform f is obtained. B1 (t), the number of cycles and the waveform f A1 (t) is the same, for example but not limited to, 10 cycles.

[0074] Step 3.3: After the measurement is completed, compare the waveforms of the electrical quantity output by the physical unit VSG #A1 and the electrical quantity output by the digital simulation unit VSG #Bi. A1 (t) and f B1 (t) Perform a comparison at the same starting point in time. If the external characteristics of the physical unit VSG #A1 and the digital simulation unit VSG #Bi are consistent, the control parameters of the digital simulation unit VSG #Bi do not need to be adjusted, and continue to step 4; if the external characteristics of the physical unit VSG #A1 and the digital simulation unit VSG #Bi are inconsistent, the control parameters of the digital simulation unit VSG #Bi need to be adjusted, and execute step 3.4; preferably, but not limited to, waveform f A1 (t) and f B1 (t) Take 10 cycles to determine whether the external characteristics of the physical unit VSG #A1 and the digital simulation unit VSG #Bi are consistent, and adjust the control parameters.

[0075] Further preferably but not limitatively, determining whether the external characteristics of the physical unit VSG #A1 and the digital simulation unit VSG #Bi are consistent includes:

[0076] Step a: Transform the waveform f A1 (t) and f B1 (t) are subjected to FFT respectively, which is expressed as follows:

[0077]

[0078]

[0079] Where:

[0080] V1 and V1 ' Represent waveform f A1 (t) and f B1 The amplitude of the fundamental wave quantity (t), ω1 and ω1 ' Represent waveform f A1 (t) and f B1 (t) is the frequency of the fundamental wave,

[0081] V j and Vj ' Represent waveform f A1 (t) and f B1 The amplitude of the jth harmonic of (t), ω j and ω j ' Represent waveform f A1 (t) and f B1 The frequency of the jth harmonic of (t), where j = 2, 3, ..., N;

[0082] N represents the number of sampling points;

[0083] Represents waveform f A1 (t) and f B1 (t) Phase difference.

[0084] Step b: Determine the waveform f based on the fundamental wave and harmonic similarity. A1 (t) and f B1 (t) Whether there is consistency.

[0085] Fundamental wave similarity judgment includes: waveform f A1 (t) and f B1 If the amplitude difference, frequency difference and phase difference of the FFT fundamental wave of (t) are all less than the set value or ratio, the fundamental wave has consistency, preferably but not limited to, the amplitude difference ΔV ≤ 1%; the frequency difference Δf ≤ 0.1%; the phase difference ≤0.5°, expressed as follows:

[0086]

[0087] Harmonic similarity judgment includes: the FFT harmonic amounts of each waveform should be basically proportional. The number of harmonics to be taken depends on the actual situation. The similarity judgment standard for 2nd and above harmonics is that the amplitude or frequency deviation of the corresponding frequency harmonic is less than the set value or ratio. Preferably, but not limited to, the deviation ratio is less than 5%, which is expressed as the following formula:

[0088]

[0089] Where:

[0090] A i Represents waveform f A1 (t) harmonic amplitude or frequency, A i ' represents the waveform f B1 The harmonic amplitude or frequency of (t) can be substituted into the waveform f obtained in the FFT formula in step a. A1 (t) and f B1 (t) harmonic amplitude V j and V j'Perform harmonic similarity judgment, or waveform f can also be substituted A1 (t) and f B1 (t) of the harmonic frequency ω j and ω j ' to perform harmonic similarity judgment.

[0091] If both the fundamental wave and harmonic similarity judgments meet the consistency, then whether the waveforms f A1 (t) and f B1 (t) have consistency, that is, the external characteristics of the physical unit VSG #A1 and the digital simulation unit VSG #Bi are consistent.

[0092] Step 3.4: Adjust the parameters of the digital simulation unit VSG #Bi, including: the time t of the delay / lead link d , the voltage loop control parameters, such as but not limited to, the voltage control loop proportional parameter K up , the integral parameter K ui , the current loop control loop proportional parameter K ip , the integral parameter K ii and the line impedance Z eq of at least one of them, and update the corresponding control parameters stored in Step 2 with the adjusted control parameters of the digital simulation unit VSG #Bi, and return to Step 3.2.

[0093] It can be understood that by adjusting these parameters, Steps 3.2 to 3.4 are repeatedly executed to achieve the equivalent effect of the digital simulation unit VSG #B1 and the physical unit VSG #A1, that is, they nearly have the same external characteristics.

[0094] It should be noted that the digital simulation unit used for the grid connection pre-test of a physical unit remains connected to the grid in the digital simulation model. The physical unit VSG #A1 replaces the physical unit one by one, and the corresponding digital simulation unit is established and remains connected to the grid, realizing the grid connection pre-test of the physical unit group. That is, the present invention provides a more practical digital simulation unit group modeling method. As one of the prominent substantive features of the present invention, high-precision modeling of the digital simulation unit is carried out by the physical unit, and the grid connection test of each unit is carried out under the condition of multi-unit parallel connection, quickly completing the task of large-scale grid connection pre-test of the inverter.

[0095] Step 4: Judge whether the grid connection pre-test of all physical units has been completed. If not, return to Step 2 to perform the grid connection pre-test of the next physical unit. If it has been completed, execute Step 5.

[0096] Specifically, if the current i < N C , then it has not been completed, return to Step 2. If i = N C , the grid connection pre-test of the last physical unit has been completed, execute Step 5.

[0097] Step 5: Export the control parameters saved in the storage medium to the corresponding physical units and connect to the grid.

[0098] Specifically, export the control parameters corresponding to each physical unit saved in the storage medium to the units that actually need to be connected to the grid for formal grid connection. For example, the parameters of Unit 2 imported during modeling, after fine-tuning and saved in the storage medium with the parameter setting numbered 2, are returned to the actual Unit 2 that needs to be connected to the grid. The same applies to the other units, corresponding one by one in sequence. Finally, export the parameters of the physical units saved in the storage medium to the units that are actually connected to the grid for grid connection.

[0099] As one of the prominent substantive features of the present invention, the parameter tuning method in this method not only ensures that the external environment of the physical unit is similar to that of the actual unit when connecting to the grid, gives highly credible results when implementing large-scale grid connection pre-tests, but also reduces the cost and threshold of physical unit tests. It is equivalent to providing a platform for grid connection tests of single or multiple physical units, ensuring that the connection environment is consistent on the digital side and the physical side when the actual unit is connected to the grid, and can conduct pre-tests and parameter corrections for large-scale grid connection of inverters in advance, improving the grid connection efficiency and reducing the threshold and cost of physical tests.

[0100] Furthermore, this method is not only applicable to the scenario of large-scale grid connection of network-forming inverters. In the present invention, a typical network-forming scenario is used to illustrate the feasibility. In fact, it can also achieve similar effects for network-following and network-forming hybrid types and network-following inverters.

[0101] Embodiment 2 of the present invention provides a parameter tuning system for large-scale grid connection of network-forming inverters, which runs the parameter tuning method for large-scale grid connection of network-forming inverters described in Embodiment 1, including: a physical unit module, a physical-digital interface module, and a digital simulation model. The physical unit module is connected to the digital simulation model through the physical-digital interface module;

[0102] The physical unit module includes: a physical unit VSG #A1, an adjustable impedance unit, a physical unit measurement unit, and a physical unit switch unit SW A1 ; the physical unit VSG #A1, the adjustable impedance unit, and the physical unit switch unit SW A1 are connected in sequence to form branch A1; the physical unit measurement unit is used to measure the electrical quantities of branch A1.

[0103] Preferably but not limited thereto, the physical unit VSG #A1 includes: a first DC bus power supply interface, a first grid-connected inverter, and a first inverter controller; the first DC bus power supply interface is a physical device, and the power sources include at least one of a wind turbine plus a machine-side rectifier, a photovoltaic array, and an energy storage battery; the first DC bus power supply interface is connected to the input end of the first grid-connected inverter, and the output end of the first grid-connected inverter is connected to the physical-digital interface module via the physical unit switch unit SW A1 is connected to the physical-digital interface module; the inverter controller is connected to the first grid-connected inverter.

[0104] The digital simulation model includes: a digital unit module, a collecting bus module, and a power grid module; the digital unit module is connected to the power grid module via the collecting bus module, and the physical-digital interface module is connected to the collecting bus module.

[0105] Preferably but not limited thereto, the digital unit module includes: N digital simulation units, not less than the number of physical units to be connected to the grid, and each digital simulation unit VSG #Bi represents each digital simulation unit, where i = 1, 2, ···, N; each digital simulation unit VSG #Bi is connected to the collecting bus module via a digital simulation impedance unit Z Bi and a digital simulation switch unit SW Bi to form multiple branches i connected to the collecting bus module, and each branch i is provided with a digital simulation unit measurement unit i for measuring the electrical quantities of branch i;

[0106] The digital simulation unit VSG #Bi includes: a second DC bus power supply interface, a second grid-connected inverter, and a second inverter controller; the second DC bus power supply interface, the second grid-connected inverter, and the second inverter controller of the digital simulation unit VSG #Bi are simulation models; the second inverter controller includes: a delay / lead link for adjusting parameters to make the output of the physical unit VSG #A1 consistent with that of the digital simulation unit VSG #Bi.

[0107] The collecting bus module includes: a collecting bus and a bus measurement unit for measuring the electrical quantities of the bus; each digital simulation unit VSG #Bi can be connected to the collecting bus as a branch;

[0108] The power grid module includes: a digital simulation power grid G1 and a power grid impedance Z g ; the collecting bus is connected to the digital simulation power grid G1 via the power grid impedance Z g ; wherein, the digital simulation power grid G1 and the power grid impedance Z g are determined according to the parameters of the local grid connection.

[0109] The physical-digital interface module includes: an active four-quadrant power amplifier and a digital simulation interface; the physical unit VSG#A1 outputs an analog AC signal through the first grid-connected inverter, and after passing through the active four-quadrant power amplifier, the analog quantity is converted into a digital quantity and enters the digital simulation model.

[0110] Embodiment 3 of the present invention provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the computer program is loaded into the processor, it implements the parameter tuning method for large-scale grid connection of a grid-forming inverter according to Embodiment 1.

[0111] Embodiment 4 of the present invention provides a computer-readable storage medium. The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, it implements the parameter tuning method for large-scale grid connection of a grid-forming inverter according to Embodiment 1.

[0112] The present disclosure may be a system, a method, and / or a computer program product. The computer program product may include a computer-readable storage medium having thereon computer-readable program instructions for causing a processor to implement various aspects of the present disclosure.

[0113] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: it is still possible to modify the specific implementation manners of the present invention or make equivalent replacements, and any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A parameter setting method for large-scale grid connection of a network-forming inverter, characterized in that, Including the following steps: Step 1: Establish a virtual-real fusion topology structure including a physical unit module, a physical-digital interface module, and a digital simulation model; wherein, the physical unit module is connected to the digital simulation model through the physical-digital interface module, and the digital simulation model is used to simulate the grid-connected topology structure of a new energy grid-forming substation; the physical unit module includes: a physical unit measurement unit, branch A1, and branch A1 includes a physical unit VSG #A1, an adjustable impedance unit, and a physical unit switch unit SWA1 connected in sequence; the physical unit measurement unit is respectively connected to the adjustable impedance unit and the physical unit switch unit SWA1, and the physical unit VSG #A1 includes: a first DC bus power supply interface, a first grid-connected inverter, and a first inverter controller; the first DC bus power supply interface is connected to the input end of the first grid-connected inverter, the output end of the first grid-connected inverter is connected to the physical-digital interface module through the physical unit switch unit SWA1, and the first inverter controller is connected to the first grid-connected inverter; Step 2: According to the set order of each physical unit, give the parameters of the physical unit to be pre-tested for grid connection to the physical unit VSG #A1, and connect the physical unit VSG #A1 that obtains the parameters of the physical unit to the digital simulation model. After the physical unit VSG #A1 is debugged and stabilized, save the current operation control parameters of the physical unit VSG #A1 as the control parameters of the physical unit to the storage medium; Step 3: Disconnect the connection between the physical unit VSG #A1 and the digital simulation model, and establish a digital simulation unit in the digital simulation model that is consistent with the external characteristics of the physical unit VSG #A1, and keep the digital simulation unit connected to the grid in the digital simulation model to complete the grid connection pre-test of one physical unit; Step 4: Determine whether the grid connection pre-test of all physical units has been completed. If not, return to Step 2 to perform the grid connection pre-test of the next physical unit. If it has been completed, execute Step 5; Step 5: Export the control parameters saved in the storage medium to the corresponding physical units.

2. A parameter setting method for large-scale grid connection of a grid-forming inverter according to claim 1, characterized in that: The digital simulation model includes: a digital unit module, a collecting bus module, and a power grid module; the digital unit module is connected to the power grid module through the collecting bus module, and the physical-digital interface module is connected to the collecting bus module.

3. A parameter setting method for large-scale grid connection of a grid-forming inverter according to claim 2, characterized in that: The digital unit module includes: N D digital simulation units VSG #Bi, where i = 1, 2, ⋯, N D , and each digital simulation unit VSG #Bi is connected to the collecting bus module via a digital simulation impedance unit Z Bi and a digital simulation switch unit SW Bi to form multiple branches i connected to the collecting bus module, and each branch i is provided with a digital simulation unit measurement unit i; The digital simulation unit VSG #Bi includes: a second DC bus power supply interface, a second grid-connected inverter, and a second inverter controller. The second DC bus power supply interface is connected to the input end of the second grid-connected inverter. The output end of the second grid-connected inverter passes through a digital simulation impedance unit Z Bi and a digital simulation switch unit SW Bi and is connected to the aggregated bus module; the second inverter controller includes a delay / lead link and is connected to the second grid-connected inverter.

4. A parameter setting method for large-scale grid connection of a grid-forming inverter according to claim 3, characterized in that: Step 2 includes: Assign a serial number to the grid connection pre-test according to the number of the physical unit to be pre-tested for grid connection; After the parameters of the physical unit VSG #Ci are given to the physical unit VSG #A1, close the physical unit switch unit SW A1 , so as to connect the physical unit VSG #A1 to the digital simulation model through the physical-digital interface module, i = 1, 2, ⋯, N C ; after the physical unit VSG #A1 reaches stable operation through debugging, measure the electrical quantities of branch A1 with the physical unit measurement unit to obtain the first electrical quantities of branch A1. The first electrical quantities include voltage, current and phase angle, and output the first electrical quantities to the collecting busbar module of the digital simulation model to save its waveform f A1 (t) to the storage medium; Save the current operation control parameters of the physical unit VSG #A1 as the control parameters of the replaced physical unit VSG #Ci to the storage medium.

5. A parameter setting method for large-scale grid connection of a grid-forming inverter according to claim 4, characterized in that: Step 3 includes: Disconnect the physical unit VSG #A1, and model the digital simulation unit VSG #Bi in the digital simulation model according to the current operation control parameters of the physical unit VSG #A1 to obtain the digital simulation unit VSG #Bi to be connected. Closed digital simulation switch unit SW Bi , to access the digital simulation unit VSG #Bi, and use the digital simulation unit measurement unit i and the bus measurement unit to measure the electrical quantities on branch i and the collection bus respectively to obtain the second electrical quantities for multiple cycles, and obtain the waveform f according to the second electrical quantities for multiple cycles B1 (t), the number of cycles is the same as the waveform f A1 (t); Judge whether the external characteristics of the physical unit VSG #A1 and the digital simulation unit VSG #Bi are consistent. If they are consistent, execute step 4; if they are not consistent, adjust the control parameters of the digital simulation unit VSG #Bi until the external characteristics of the physical unit VSG #A1 and the digital simulation unit VSG #Bi are consistent, and then update the corresponding control parameters stored in step 2 with the adjusted control parameters of the digital simulation unit VSG #Bi, and continue to execute step 4.

6. The parameter setting method for large-scale grid-connected network-forming inverters according to claim 5, characterized in that: Judging whether the external characteristics of the physical unit VSG #A1 and the digital simulation unit VSG #Bi are consistent includes: Perform FFT processing on waveforms f A1 (t) and f B1 (t) respectively to obtain the parameters of the fundamental wave component and harmonic component in waveforms f A1 (t) and f B1 (t). Then, based on the parameters of the fundamental wave component and harmonic component in waveforms f A1 (t) and f B1 (t), determine whether waveforms f A1 (t) and f B1 (t) are consistent.

7. The parameter setting method for large-scale grid-connected network-forming inverters according to claim 6, characterized in that: According to the parameters of the fundamental wave quantity and harmonic wave quantity in waveform f A1 (t) and f B1 (t), determine whether waveforms f A1 (t) and f B1 (t) are consistent, including that the amplitude difference, frequency difference, and phase difference of the fundamental wave quantity in waveforms f A1 (t) and f B1 (t) are all less than the set value or ratio. If so, the fundamental wave quantities in waveforms f A1 (t) and f B1 (t) are consistent; When the waveform f A1 (t) and f B1 (t) have an amplitude difference, a frequency difference, and a phase difference of corresponding frequency harmonic components that are less than a set value or ratio, then the harmonic components in the waveform f A1 (t) and f B1 (t) are consistent; If the waveform f A1 (t) and f B1 (t) have consistency in both fundamental wave components and harmonic components, then the external characteristics of the physical unit VSG #A1 and the digital simulation unit VSG #Bi are consistent.

8. The parameter setting method for large-scale grid-connected network-forming inverters according to claim 6 or 7, characterized in that: Adjust the VSG #Bi parameters of the digital simulation unit, including: the time t of the delay / lead link d , adjust the proportional parameter K of the voltage control loop up , the integral parameter K ui , the proportional parameter K of the current loop control loop ip , the integral parameter K ii and the line impedance Z eq at least one of them.

9. A parameter setting system for large-scale grid connection of a network-forming inverter, which is used to execute a parameter setting method for large-scale grid connection of a network-forming inverter according to any one of claims 1 to 8, characterized in that, Includes: A physical unit module, a physical-digital interface module, and a digital simulation model. The physical unit module is connected to the digital simulation model through the physical-digital interface module; The physical unit module includes: physical unit VSG #A1, adjustable impedance unit, physical unit measurement unit, and physical unit switch unit SW A1 ; the physical unit VSG #A1, adjustable impedance unit, and physical unit switch unit SW A1 are connected in sequence to form branch A1; the physical unit measurement unit is used to measure the electrical quantities of branch A1; The digital simulation model includes: a digital unit module, a converging bus module, and a power grid module.

10. The parameter setting system for large-scale grid-connected network-forming inverters according to claim 9, characterized in that: The physical-digital interface module includes: an active four-quadrant power amplifier and a digital simulation interface; the physical unit VSG #A1 outputs an analog AC signal through a grid-connected inverter, and after passing through the active four-quadrant power amplifier, the analog quantity is converted into a digital quantity and enters the digital simulation model.

11. The parameter setting system for large-scale grid-connected network-forming inverters according to claim 9, characterized in that: The physical unit VSG #A1 includes: a first DC bus power supply interface, a first grid-connected inverter, and a first inverter controller; the first DC bus power supply interface is a physical device, and the power sources include at least one of a wind turbine plus a machine-side rectifier, a photovoltaic array, and an energy storage battery; the first DC bus power supply interface is connected to the input end of the first grid-connected inverter, and the output end of the first grid-connected inverter is connected to the physical-digital interface module through the physical unit switch unit SW A1 and is connected to the physical-digital interface module; the first inverter controller is connected to the first grid-connected inverter.

12. The parameter setting system for large-scale grid-connected network-forming inverters according to claim 9, characterized in that: The digital unit module includes: N D digital simulation units, the number of which is not less than the number of physical units to be connected to the grid. Each digital simulation unit is denoted as VSG #Bi, where i = 1, 2, ⋯, N D ; each digital simulation unit VSG #Bi is connected to the busbar collection module via a digital simulation impedance unit Z Bi and a digital simulation switch unit SW Bi to form multiple branches i connected to the busbar collection module. Each branch i is provided with a digital simulation unit measurement unit i for measuring the electrical quantities of branch i; The digital simulation unit VSG #Bi includes: a second DC bus power supply interface, a second grid-connected inverter, and a second inverter controller; the second DC bus power supply interface, the second grid-connected inverter, and the second inverter controller of the digital simulation unit VSG #Bi are simulation models; the second inverter controller includes: a delay / lead link for adjusting parameters to make the outputs of the physical unit VSG #A1 and the digital simulation unit VSG #Bi consistent.

13. The parameter setting system for large-scale grid-connected network-forming inverters according to claim 12, characterized in that: The converging bus module includes: a converging bus and a bus measurement unit for measuring bus electrical quantities; each digital simulation unit VSG #Bi can be connected to the converging bus as a branch; The power grid module includes: a digital simulation power grid G1 and a power grid impedance Z g ; the collecting bus is connected to the digital simulation power grid G1 through the power grid impedance Z g ; wherein, the digital simulation power grid G1 and the power grid impedance Z g are determined according to the parameters of the local grid connection.

14. An electronic device, comprising: A memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that when the computer program is loaded into the processor, it implements a parameter setting method for large-scale grid connection of a network-forming inverter according to any one of claims 1 to 8.

15. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements a parameter setting method for large-scale grid connection of a network-forming inverter according to any one of claims 1 to 8.

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