Virtual voltage control method for suppressing network-forming type overcurrent and electronic equipment

Abstract

The invention provides a virtual voltage control method and electronic equipment for suppressing network-forming type overcurrent, and belongs to the technical field of overcurrent suppression, and the method comprises the steps: calculating a first virtual voltage and a second virtual voltage based on a network-forming type output voltage vector; calculating an inverter reference voltage based on the first virtual voltage, the second virtual voltage and the grid-forming type output voltage vector; on the basis of the inverter reference voltage and the mathematical model of the network construction type in the static coordinate system, suppressing the overcurrent of the network construction type equipment in the network construction type, and suppressing the overvoltage of the inverter in the network construction type on the basis of the second virtual voltage; wherein the overcurrent of the network construction type equipment is caused by symmetrical or asymmetrical voltage drop and recovery; and controlling the network configuration type based on the output current of the network configuration type equipment after the overcurrent suppression and the output voltage of the inverter after the overvoltage suppression. According to the scheme of the invention, overcurrent caused by symmetric or asymmetric voltage drop and recovery can be comprehensively suppressed.

Description

Technical Field

[0001] The present application relates to the technical field of overcurrent suppression, and in particular to a virtual voltage control method and electronic device for suppressing grid-type overcurrent. Background Art

[0002] Grid-based control is a power system control method based on positive-negative sequence separation and positive-negative sequence control. It achieves stable regulation of grid voltage and balanced control of three-phase current through voltage and current dual-loop control.

[0003] At present, there are some methods for suppressing overcurrent caused by voltage drop and recovery in the prior art, such as the coordinated suppression method based on harmonic current and inrush fault current. However, due to the complexity of system analysis and design difficulty, this suppression method can only suppress overcurrent caused by symmetrical voltage drop and recovery, and it is difficult to suppress overcurrent caused by asymmetrical voltage drop and recovery, which has certain limitations.

[0004] Therefore, how to comprehensively suppress overcurrent caused by symmetrical or asymmetrical voltage drop and recovery has become a problem to be solved. Summary of the invention

[0005] The purpose of the present application is to provide a virtual voltage control method for suppressing grid-type overcurrent, which can solve the problem in the prior art that it is difficult to suppress overcurrent caused by asymmetric voltage drop and recovery.

[0006] In a first aspect, an embodiment of the present application provides a virtual voltage control method for suppressing a grid-type overcurrent, the method comprising: Based on the meshed output voltage vector, a first virtual voltage and a second virtual voltage are calculated; Based on the first virtual voltage, the second virtual voltage and the meshed output voltage vector, an inverter reference voltage is calculated; Based on the inverter reference voltage and the mathematical model of the meshing type in the stationary coordinate system, the overcurrent of the meshing type device in the meshing type is suppressed, and based on the second virtual voltage, the overvoltage of the inverter in the meshing type is suppressed; wherein the overcurrent of the meshing type device is caused by symmetrical or asymmetrical voltage drop and recovery; The grid type is controlled based on the output current of the grid type device after overcurrent suppression and the output voltage of the inverter after overvoltage suppression.

[0007] In a possible implementation manner of the first aspect, before calculating the first virtual voltage and the second virtual voltage based on the meshed output voltage vector, the method further includes: According to the meshing type output voltage amplitude and the meshing type device output voltage phase, the meshing type output voltage vector is calculated. The specific calculation formula is as follows:

[0008] in, represents the grid-type output voltage vector, Indicates the output voltage amplitude of the network type, , Indicates the grid voltage amplitude, Indicates the grid voltage change, , , Indicates n The grid voltage injected into the voltage outer loop by a grid-forming device, Indicates a variable superscript, is a constant, Indicates the phase of the output voltage of the networking device.

[0009] In a possible implementation manner of the first aspect, calculating and obtaining the first virtual voltage and the second virtual voltage based on the meshed output voltage vector includes: According to the grid voltage amplitude and grid voltage phase, the first virtual voltage is calculated, and the specific calculation formula is as follows:

[0010] in, represents the first virtual voltage, represents the grid voltage vector, Indicates the grid voltage phase.

[0011] In a possible implementation manner of the first aspect, the first virtual voltage and the second virtual voltage are calculated based on the meshed output voltage vector, further comprising: According to n The grid voltage and grid voltage phase injected by each networking device into the voltage outer loop are used to calculate the second virtual voltage. The specific calculation formula is as follows:

[0012] in, represents the second virtual voltage.

[0013] In a possible implementation of the first aspect, calculating the inverter reference voltage based on the first virtual voltage, the second virtual voltage, and the meshed output voltage vector includes: The inverter reference voltage is calculated according to the following formula:

[0014] in, Indicates the inverter reference voltage.

[0015] In a possible implementation of the first aspect, a mathematical model of the grid type in the abc stationary coordinate system is as follows:

[0016]

[0017]

[0018] in, Represents the grid current, Indicates time, represents the resistance of the filter in the network configuration, represents the inductance of the filter in the network configuration, Indicates the output frequency of the networking device, variable subscript pu is the normalized value, Indicates the reference active power of the network-building equipment. Indicates the active power injected into the grid by the grid-forming equipment. represents the damping constant, represents the virtual inertia constant, Indicates the grid frequency, Indicates the phase difference angle when the voltage drops.

[0019] In a possible implementation of the first aspect, based on the inverter reference voltage and the mathematical model of the meshing type in the stationary coordinate system, suppressing the overcurrent of the meshing type device in the meshing type includes: The calculation formula of the inverter reference voltage and the second formula in the mathematical model of the grid type in the abc stationary coordinate system are combined to obtain the following calculation formula:

[0020] in, It represents the component of the grid current on the a-axis of the abc stationary coordinate system, It represents the component of the grid current on the b-axis of the abc stationary coordinate system, Represents the c-axis component of the grid current in the abc stationary coordinate system; The overcurrent of the meshing equipment in the meshing type is suppressed according to the formula.

[0021] In a possible implementation of the first aspect, suppressing an overvoltage of an inverter in a grid-type based on a second virtual voltage includes: like ,and , the inverter outputs a preset voltage; The preset voltage is replaced by a second virtual voltage to suppress overvoltage of the inverter in the grid-type.

[0022] In a second aspect, an embodiment of the present application provides a virtual voltage control device for suppressing grid-type overcurrent, the device comprising: A first calculation unit, configured to calculate a first virtual voltage and a second virtual voltage based on a meshed output voltage vector; A second calculation unit, configured to calculate an inverter reference voltage based on the first virtual voltage, the second virtual voltage and the meshed output voltage vector; A suppression unit, for suppressing an overcurrent of a meshing device in the meshing type based on an inverter reference voltage and a mathematical model of the meshing type in a stationary coordinate system, and suppressing an overvoltage of an inverter in the meshing type based on a second virtual voltage; wherein the overcurrent of the meshing device is caused by a symmetrical or asymmetrical voltage drop and recovery; The control unit is used to control the grid type based on the output current of the grid type device after overcurrent suppression and the output voltage of the inverter after overvoltage suppression.

[0023] In a third aspect, an embodiment of the present application 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 computer program, the virtual voltage control method for suppressing grid-type overcurrent according to any one of the above-mentioned first aspects is implemented.

[0024] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, it implements the virtual voltage control method for suppressing grid-type overcurrent of any one of the above-mentioned first aspects.

[0025] In a fifth aspect, an embodiment of the present application provides a computer program product. When the computer program product is run on an electronic device, the electronic device executes any one of the virtual voltage control methods for suppressing grid-type overcurrent in the first aspect.

[0026] The solution of the present application calculates a first virtual voltage and a second virtual voltage based on a meshing type output voltage vector; calculates an inverter reference voltage based on the first virtual voltage, the second virtual voltage and the meshing type output voltage vector; suppresses overcurrent of meshing type devices in the meshing type based on the inverter reference voltage and a mathematical model of the meshing type in a stationary coordinate system, and suppresses overvoltage of the inverter in the meshing type based on the second virtual voltage; wherein the overcurrent of the meshing type devices is caused by symmetrical or asymmetrical voltage drops and recovery; and controls the meshing type based on the output current of the meshing type devices after overcurrent suppression and the inverter output voltage after overvoltage suppression.

[0027] The application scheme can comprehensively suppress overcurrent caused by symmetrical or asymmetrical voltage drop and recovery, and has strong ease of use and practicality.

[0028] Other features and advantages of the present application will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0030] Figure 1 It is a schematic diagram of an application scenario provided by an embodiment of the present application; Figure 2 It is a schematic diagram of the steps of a virtual voltage control method for suppressing grid-type overcurrent provided in an embodiment of the present application; Figure 3 is a schematic block diagram of a traditional networking controller according to an embodiment of the present application; Figure 4 is a schematic block diagram of the calculation of the positive phase sequence component provided in an embodiment of the present application; Figure 5 is a schematic block diagram of a phase-locked loop provided in an embodiment of the present application; Figure 6 It is a schematic diagram of voltage drop and recovery provided in an embodiment of the present application; Figure 7 is a schematic block diagram of a networking controller provided in an embodiment of the present application; Figure 8 is a schematic diagram of a meshed equivalent circuit of a meshed control method provided in an embodiment of the present application; Fig. 9 It is a structural schematic diagram of a virtual voltage control device for suppressing grid-type overcurrent provided in an embodiment of the present application; Fig.10 It is a schematic diagram of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0031] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

[0032] It should be understood that when used in this specification and the appended claims, the term "comprising" indicates the presence of described features, integers, steps, operations, elements and / or photovoltaic components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, photovoltaic components and / or combinations thereof.

[0033] It should also be understood that the terms used in this application specification are only for the purpose of describing specific embodiments and are not intended to limit the application. As used in this application specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0034] It should be further understood that the term “and / or” used in the specification and appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0035] As used in this specification and the appended claims, the term "if" may be interpreted as "when" or "upon" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrases "if it is determined" or "if [described condition or event] is detected" may be interpreted as meaning "upon determination" or "in response to determining" or "upon detection of [described condition or event]" or "in response to detecting [described condition or event]," depending on the context.

[0036] In addition, in the description of the present application, the terms "first", "second", "third", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0037] References to "one embodiment" or "some embodiments" etc. described in the specification of this application mean that one or more embodiments of the present application include specific features, structures or characteristics described in conjunction with the embodiment. Therefore, the statements "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0038] Grid-based control is a power system control method based on positive-negative sequence separation and positive-negative sequence control. It achieves stable regulation of grid voltage and balanced control of three-phase current through voltage and current dual-loop control.

[0039] At present, there are some methods for suppressing overcurrent caused by voltage drop and recovery in the prior art, such as the coordinated suppression method based on harmonic current and inrush fault current. However, this suppression method requires additional filter inductors and voltage sensors, which increases losses and costs. In addition, due to the complexity of system analysis and design difficulty, it can only suppress overcurrent caused by symmetrical voltage drop and recovery, and it is difficult to suppress overcurrent caused by asymmetrical voltage drop and recovery, which has certain limitations.

[0040] Therefore, how to comprehensively suppress overcurrent caused by symmetrical or asymmetrical voltage drop and recovery has become a problem to be solved.

[0041] In response to the above-mentioned defects, an embodiment of the present application provides a virtual voltage control method for suppressing meshing type overcurrent, wherein a first virtual voltage and a second virtual voltage are calculated based on the meshing type output voltage vector; an inverter reference voltage is calculated based on the first virtual voltage, the second virtual voltage and the meshing type output voltage vector; based on the inverter reference voltage and a mathematical model of the meshing type in a stationary coordinate system, an overcurrent of a meshing type device in the meshing type is suppressed, and based on the second virtual voltage, an overvoltage of the inverter in the meshing type is suppressed; wherein the overcurrent of the meshing type device is caused by symmetrical or asymmetrical voltage drop and recovery; based on the output current of the meshing type device after overcurrent suppression, and the inverter output voltage after overvoltage suppression, the meshing type is controlled.

[0042] The application scheme can comprehensively suppress overcurrent caused by symmetrical or asymmetrical voltage drop and recovery, and has strong ease of use and practicality.

[0043] See also Figure 1 , Figure 1 Schematic diagram of the application scenario provided by the embodiment of the present application. Figure 1 As shown in the figure, the voltage-controlled grid-type includes: distributed generation units (DGU, Distributed Generation Units), energy storage system (ESS, Energy Storage System, Energy Storage System), voltage source inverter (VSI, Voltage Source Inverter) and grid-type controller. It is connected to the grid through filters and transformers (TRS, Transformer).

[0044] The specific process implemented by this application is introduced below through specific embodiments.

[0045] See also Figure 2 , Figure 2 Schematic diagram of the steps of the virtual voltage control method for suppressing grid-type overcurrent provided in the embodiment of the present application. Figure 2 As shown, the method comprises the following steps: S201 , calculating and obtaining a first virtual voltage and a second virtual voltage based on a meshed output voltage vector.

[0046] In some embodiments, the grid configuration operates according to the swing equation of the synchronous generator, and the specific formula is as follows:

[0047]

[0048] in, It is the active power reference value of the network-building equipment; Active power injected into the grid for grid-forming devices, and , is the grid voltage, is the grid current; is the virtual inertia constant; is the output frequency of the network-building device; D is the damping constant; is the grid frequency; is the output voltage phase of the networking device; the variable subscript pu is the normalized value.

[0049] In some embodiments, Figure 3 As shown, the inverter reference voltage is calculated according to the following formula:

[0050] In the formula, is the inverter reference voltage; , Indicates the output voltage amplitude of the network type, Indicates the grid voltage amplitude, Indicates the grid voltage change.

[0051] In the prior art, such as Figure 4 As shown, Components of the grid voltage in the rotating coordinate system can be Figure 4 Conclude. , to enhance the low voltage ride-through capability under unbalanced grid voltage. In one embodiment, in order to prevent overcurrent caused by grid acceleration during voltage drop, Modified to .

[0052] In some embodiments, Figure 5 As shown, the phase-locked loop is used to calculate , , as well as These are all estimated values ​​in the PLL (Phase-Locked Loop). Assume .also, Figure 4 and Figure 5 The transformation matrix in and The definition formula is as follows:

[0053]

[0054] In some embodiments, the grid-type control is equipped with an automatic voltage controller (AVR, Automatic Voltage Regulation) to regulate and The AVR built here has anti-saturation capability. The energy storage system controls the DC converter, and this embodiment focuses on the grid-type converter, so the energy storage and its DC part dynamics can be ignored. .

[0055] According to an implementation manner of the present application, before calculating the first virtual voltage and the second virtual voltage based on the meshed output voltage vector, the method further includes: According to the meshing type output voltage amplitude and the meshing type device output voltage phase, the meshing type output voltage vector is calculated. The specific calculation formula is as follows:

[0056] in, represents the grid-type output voltage vector, Indicates the output voltage amplitude of the network type, , Indicates the grid voltage amplitude, Indicates the grid voltage change, , , Indicates n The grid voltage injected into the voltage outer loop by a grid-forming device, Indicates a variable superscript, is a constant, Indicates the phase of the output voltage of the networking device.

[0057] According to an implementation manner of the present application, based on the meshed output voltage vector, calculating the first virtual voltage and the second virtual voltage includes: According to the grid voltage amplitude and grid voltage phase, the first virtual voltage is calculated, and the specific calculation formula is as follows:

[0058] in, represents the first virtual voltage, represents the grid voltage vector, Indicates the grid voltage phase.

[0059] According to an implementation manner of the present application, based on the meshed output voltage vector, calculating the first virtual voltage and the second virtual voltage further includes: According to n The grid voltage and grid voltage phase injected by each networking device into the voltage outer loop are used to calculate the second virtual voltage. The specific calculation formula is as follows:

[0060] in, represents the second virtual voltage.

[0061] S202: Calculate an inverter reference voltage based on the first virtual voltage, the second virtual voltage, and the meshed output voltage vector.

[0062] like Figure 7 As shown, according to an embodiment of the present application, based on the first virtual voltage, the second virtual voltage and the meshed output voltage vector, the inverter reference voltage is calculated, including: The inverter reference voltage is calculated according to the following formula:

[0063] in, Indicates the inverter reference voltage.

[0064] In traditional networking controllers, .like Figure 8 As shown, in this control method, VVC (Virtual voltage control) is added to the traditional control method, where quilt Therefore, the network type using this control method does not need additional equipment, such as a fault current limiter. In addition, in this control method, there is no need to adjust parameters in the VVC, and the structure is simple.

[0065] S203, based on the inverter reference voltage and the mathematical model of the meshing type in the stationary coordinate system, suppress the overcurrent of the meshing type device in the meshing type, and suppress the overvoltage of the inverter in the meshing type based on the second virtual voltage; wherein the overcurrent of the meshing type device is caused by symmetrical or asymmetrical voltage drop and recovery.

[0066] According to one implementation of the present application, the mathematical model of the grid type in the abc stationary coordinate system is as follows:

[0067]

[0068]

[0069] in, Represents the grid current, Indicates time, represents the resistance of the filter in the network configuration, represents the inductance of the filter in the network configuration, Indicates the output frequency of the networking device, variable subscript pu is the normalized value, Indicates the reference active power of the network-building equipment. Indicates the active power injected into the grid by the grid-forming equipment. represents the damping constant, represents the virtual inertia constant, Indicates the grid frequency, Indicates the phase difference angle when the voltage drops.

[0070] In one embodiment, To simplify the model, the dynamic characteristics of the AVR are ignored.

[0071] In some embodiments, in the dq rotating coordinate system, the specific calculation formula is as follows:

[0072] in, and They are The d and q axis components; and They are The d and q axis components.

[0073] When the grid-type converter adopts d-axis voltage orientation, there is = , =0. By Adjustment To reduce the overcurrent amplitude. Therefore, The expression is as follows:

[0074] Right now:

[0075] exist Figure 3 In, assuming .like Figure 6 As shown, the voltage drops [at time t1, from 1p.u. to (1− )pu] and recovery [at time t2, from (1− )pu rises to 1p.u.], under transient conditions, the dynamic characteristics of (7) and (8) can be ignored because their dynamic changes are slower than (9), and during voltage dips, .

[0076] Therefore, the current during voltage drop and recovery can be analyzed based on (9). During symmetrical voltage drop and recovery, and As shown in formula (11):

[0077] In the formula, and Respectively in Figure 6 The time interval shown arrive The steady-state current in is the transient current caused by voltage drop / recovery. From (9), (10) and ,Right now , the transient current expression can be determined as shown in formula (12):

[0078] In the formula, is the phase difference angle before the voltage drop, and

[0079] The second term on the right side of formula (12) is the transient voltage, even though in formula (3) Therefore, even if the grid-connected output voltage is adjusted to the grid voltage during the voltage sag / recovery period, the transient voltage will cause transient current to flow.

[0080] According to an implementation of the present application, based on the inverter reference voltage and the mathematical model of the grid type in the stationary coordinate system, the overcurrent of the grid type device in the grid type is suppressed, including: The calculation formula of the inverter reference voltage and the second formula in the mathematical model of the grid type in the abc stationary coordinate system are combined to obtain the following calculation formula:

[0081] in, It represents the component of the grid current on the a-axis of the abc stationary coordinate system, It represents the component of the grid current on the b-axis of the abc stationary coordinate system, Represents the c-axis component of the grid current in the abc stationary coordinate system; The overcurrent of the meshing equipment in the meshing type is suppressed according to the formula.

[0082] S204, controlling the grid type based on the output current of the grid type device after overcurrent suppression and the output voltage of the inverter after overvoltage suppression.

[0083] According to an implementation of the present application, suppressing the overvoltage of the inverter in the grid-type based on the second virtual voltage includes: like ,and , the inverter outputs a preset voltage. The preset voltage is replaced by a second virtual voltage to suppress the overvoltage of the inverter in the grid-type.

[0084] The core strategies of VVC in this control method are as follows: 1) Suppress overcurrent and unbalanced current; 2) As the grid voltage, instead of being Offset Therefore, the grid-type controller can fully improve the low voltage ride-through capability of the grid-type while maintaining the required functions (such as equivalent rotational inertia).

[0085] The embodiment of the present application clarifies the overcurrent suppression capability of the control method for the grid-type based on the above characteristics. Figure 8 (a) is the equivalent circuit of the network type using the control method proposed in this paper. , Figure 8 The equivalent circuit 1 in (a) can be redrawn as Figure 8 (b) is the equivalent circuit 2. Figure 8 (b) and formula (16), we know that quilt Offset, when ignoring the AVR (i.e. Small), ig is not affected by the amplitude of vg. Combining formula (7) and formula (17), we can get:

[0086] Transient voltage is not included in equation (18). Therefore, no matter whether the voltage drop / recovery is symmetrical or asymmetrical, it will not cause overcurrent. As the grid voltage, instead of The grid configuration based on the present control method operates according to the swing equation of the synchronous generator, and its output current and power flow according to δ, and the inherent characteristics of the grid configuration (for example, rotational inertia and synchronous power) also remain unchanged.

[0087] In addition, by observing formula (17) and formula (18), if and , the inverter must output a high voltage, which indicates Inverter overvoltage is suppressed.

[0088] The virtual voltage control method for suppressing meshing type overcurrent provided in the embodiment of the present application calculates a first virtual voltage and a second virtual voltage based on the meshing type output voltage vector; calculates an inverter reference voltage based on the first virtual voltage, the second virtual voltage and the meshing type output voltage vector; suppresses overcurrent of meshing type devices in the meshing type based on the inverter reference voltage and a mathematical model of the meshing type in a stationary coordinate system, and suppresses overvoltage of the inverter in the meshing type based on the second virtual voltage; wherein the overcurrent of the meshing type devices is caused by symmetrical or asymmetrical voltage drop and recovery; and controls the meshing type based on the output current of the meshing type devices after overcurrent suppression and the inverter output voltage after overvoltage suppression.

[0089] The application scheme can comprehensively suppress overcurrent caused by symmetrical or asymmetrical voltage drop and recovery, and has strong ease of use and practicality.

[0090] The present application solution can suppress overcurrent caused by any type of voltage drop and maintain the functions required for network construction, such as equivalent rotational inertia and synchronous power. No design parameters are required, and no additional fault current limiter is required, saving costs.

[0091] This control method can not only suppress overcurrent caused by any type of voltage drop, but also maintain the functions of the grid type, such as equivalent rotation inertia and synchronous power. In addition, this control method does not require design parameters or additional fault current limiters, reducing losses and costs.

[0092] In addition, the control method proposed in this proposal is compared with the voltage-controlled grid type and the current-controlled grid type in terms of grid control. The current-controlled grid type can reduce the overcurrent caused by voltage sag and recovery by using a current limiter, and the unbalanced current under voltage unbalance sag and recovery can also be attenuated by using the positive and negative sequence components of the grid voltage. However, due to the complexity and implementation difficulty of the current-controlled grid type, it is difficult to operate in island mode; the control method of the voltage-controlled grid type is relatively simple, and its design parameters only include the inertia constant and the damping constant. However, since the voltage-controlled grid type does not include current control and current limiters, it is difficult to suppress the overcurrent caused by voltage sag and recovery.

[0093] In contrast, the proposed grid-type overcurrent suppression control method can solve these problems. The control method proposed in the present invention can not only suppress overcurrent caused by any type of voltage drop, but also maintain the grid-type function. In addition, the control method does not require design parameters or additional fault current limiters. The proposed grid-type overcurrent suppression control method can better meet the requirements of modern power systems for high efficiency and reliability.

[0094] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0095] Corresponding to the method of the above embodiment, Fig. 9 1 is a block diagram of a virtual voltage control device for suppressing grid-type overcurrent provided by an embodiment of the present application. For ease of description, only the parts related to the embodiment of the present application are shown.

[0096] Reference Fig. 9 , the device comprises: A first calculation unit 901 is used to calculate a first virtual voltage and a second virtual voltage based on a meshed output voltage vector; A second calculation unit 902 is used to calculate an inverter reference voltage based on the first virtual voltage, the second virtual voltage and the meshed output voltage vector; The suppression unit 903 is used to suppress the overcurrent of the meshing device in the meshing type based on the inverter reference voltage and the mathematical model of the meshing type in the stationary coordinate system, and suppress the overvoltage of the inverter in the meshing type based on the second virtual voltage; wherein the overcurrent of the meshing device is caused by symmetrical or asymmetrical voltage drop and recovery; The control unit 904 is used to control the grid type based on the output current of the grid type device after overcurrent suppression and the output voltage of the inverter after overvoltage suppression.

[0097] It should be noted that the information interaction, execution process, etc. between the above-mentioned devices / units are based on the same concept as the method embodiment of the present application. Their specific functions and technical effects can be found in the method embodiment part and will not be repeated here.

[0098] Those skilled in the art can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In actual applications, the above-mentioned functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, which will not be repeated here.

[0099] Fig.10 FIG. 1 is a schematic diagram of the structure of an electronic device 10 provided in an embodiment of the present application. Fig.10 As shown, the electronic device 10 of this embodiment includes: at least one processor 101 ( Fig.10 Only one is shown in the figure), a memory 103, and a computer program 102 stored in the memory 103 and executable on at least one processor 101, and when the processor 101 executes the computer program 102, the steps in the above method embodiment are implemented.

[0100] The electronic device 10 may be a computing device such as a desktop computer, a notebook, a PDA, or a mobile phone. The electronic device 10 may include, but is not limited to, a processor 101 and a memory 103. Those skilled in the art will appreciate that Fig.10 This is only an example of the electronic device 10 and does not constitute a limitation on the electronic device 10 . The electronic device 10 may include more or fewer components than shown in the figure, or a combination of certain components, or different components. For example, it may also include input and output devices, network access devices, etc.

[0101] The processor 101 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware photovoltaic modules, etc. A general-purpose processor may be a microprocessor or any conventional processor, etc.

[0102] In some embodiments, the memory 103 may be an internal storage unit of the electronic device 10, such as a hard disk or memory of the electronic device 10. In other embodiments, the memory 103 may also be an external storage device of the electronic device 10, such as a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital card (SecureDigital, SD), a flash card (Flash Card), etc. equipped on the electronic device 10. Further, the memory 103 may also include both an internal storage unit of the electronic device 10 and an external storage device. The memory 103 is used to store an operating system, an application program, a boot loader (Boot Loader), data, and other programs, such as program codes of computer programs, etc. The memory 103 may also be used to temporarily store data that has been output or is to be output.

[0103] If the above-mentioned integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, when the present application implements all or part of the processes in the above-mentioned embodiment method, it can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a computer-readable storage medium. When the computer program is executed by the processor, it can implement the steps applied to the above-mentioned method embodiment. Among them, the computer program includes computer program code, which can be in source code form, object code form, executable file or some intermediate form. The computer-readable storage medium may at least include: any entity or device that can carry the computer program code to the computing device / electronic device, recording medium, computer memory, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), electric carrier signal, telecommunication signal and software distribution medium, such as USB flash drive, mobile hard disk, disk or optical disk. In some jurisdictions, according to legislation and patent practice, computer-readable storage media cannot be electric carrier signals and telecommunication signals.

[0104] An embodiment of the present application further provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, the steps in the above-mentioned method embodiments are implemented.

[0105] An embodiment of the present application provides a computer program product. When the computer program product is run on an electronic device, the electronic device executes the steps in the above-mentioned method embodiments.

[0106] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0107] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0108] In the embodiments provided in the present application, it should be understood that the disclosed devices / electronic devices and methods can be implemented in other ways. The device / electronic device embodiments described above are merely schematic, and the division of the above modules or units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or photovoltaic components can be combined or integrated into another system, and some features can be ignored and not executed. Another point is that the indirect coupling, direct coupling or communication connection between each other shown or discussed can be an indirect coupling, direct coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0109] The units described above as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0110] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or make equivalent replacements for some of the technical features therein. 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 application, and should all be included in the protection scope of the present application.

Claims

1. A virtual voltage control method for suppressing grid-type overcurrent, characterized in that: The method comprises: Based on the meshed output voltage vector, a first virtual voltage and a second virtual voltage are calculated; Calculating an inverter reference voltage based on the first virtual voltage, the second virtual voltage and the meshed output voltage vector; Based on the inverter reference voltage and the mathematical model of the meshing type in the stationary coordinate system, the overcurrent of the meshing type device in the meshing type is suppressed, and based on the second virtual voltage, the overvoltage of the inverter in the meshing type is suppressed; wherein the overcurrent of the meshing type device is caused by symmetrical or asymmetrical voltage drop and recovery; The grid type is controlled based on the output current of the grid type device after overcurrent suppression and the output voltage of the inverter after overvoltage suppression.

2. The virtual voltage control method for suppressing grid-type overcurrent according to claim 1, characterized in that: Before calculating the first virtual voltage and the second virtual voltage based on the meshed output voltage vector, the method further includes: According to the meshing type output voltage amplitude and the meshing type device output voltage phase, the meshing type output voltage vector is calculated, and the specific calculation formula is as follows: in, represents the grid-type output voltage vector, Indicates the output voltage amplitude of the network type, , Indicates the grid voltage amplitude, Indicates the grid voltage change, , , Indicates n The grid voltage injected into the voltage outer loop by a grid-forming device, Indicates a variable superscript, is a constant, Indicates the phase of the output voltage of the networking device.

3. The virtual voltage control method for suppressing grid-type overcurrent according to claim 2, characterized in that: Based on the meshed output voltage vector, a first virtual voltage and a second virtual voltage are calculated, including: The first virtual voltage is calculated according to the grid voltage amplitude and the grid voltage phase. The specific calculation formula is as follows: in, represents the first virtual voltage, represents the grid voltage vector, Indicates the grid voltage phase.

4. The virtual voltage control method for suppressing grid-type overcurrent according to claim 3, characterized in that: Based on the meshed output voltage vector, a first virtual voltage and a second virtual voltage are calculated, and further comprising: According to n The grid voltage and grid voltage phase of each grid-forming device injected into the voltage outer loop are used to calculate the second virtual voltage. The specific calculation formula is as follows: in, represents the second virtual voltage.

5. The virtual voltage control method for suppressing grid-type overcurrent according to claim 4, characterized in that: The method of calculating an inverter reference voltage based on the first virtual voltage, the second virtual voltage and the meshed output voltage vector includes: The inverter reference voltage is calculated according to the following formula: in, Indicates the inverter reference voltage.

6. The virtual voltage control method for suppressing grid-type overcurrent according to claim 1, characterized in that: The mathematical model of the network type in the abc stationary coordinate system is as follows: in, Represents the grid current, Indicates time, represents the resistance of the filter in the network configuration, represents the inductance of the filter in the network configuration, Indicates the output frequency of the networking device, variable subscript pu is the normalized value, Indicates the reference active power of the network-building equipment. Indicates the active power injected into the grid by the grid-forming equipment. represents the damping constant, represents the virtual inertia constant, Indicates the grid frequency, Indicates the phase difference angle when the voltage drops.

7. The virtual voltage control method for suppressing grid-type overcurrent according to claim 6, characterized in that: Based on the inverter reference voltage and the mathematical model of the grid type in the stationary coordinate system, overcurrent of the grid type device in the grid type is suppressed, including: The calculation formula of the inverter reference voltage and the second formula in the mathematical model of the grid type in the abc stationary coordinate system are combined to obtain the following calculation formula: in, It represents the component of the grid current on the a-axis of the abc stationary coordinate system, It represents the component of the grid current on the b-axis of the abc stationary coordinate system, Represents the c-axis component of the grid current in the abc stationary coordinate system; The overcurrent of the meshing equipment in the meshing type is suppressed according to the formula.

8. The virtual voltage control method for suppressing grid-type overcurrent according to any one of claims 1 to 7, characterized in that: The overvoltage of the inverter in the grid-type is suppressed based on the second virtual voltage, including: like ,and , the inverter outputs a preset voltage; The preset voltage is replaced by the second virtual voltage to suppress overvoltage of the inverter in the grid-type.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the virtual voltage control method for suppressing grid-type overcurrent described in any one of claims 1 to 8 is implemented.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the virtual voltage control method for suppressing grid-type overcurrent described in any one of claims 1 to 8 is implemented.

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