Virtual synchronous control-based grid-connection stability analysis method for network-building converter

Abstract

The invention discloses a virtual synchronous control-based grid-connected stability analysis method for a network-constructed converter. The method comprises the following steps of: constructing a virtual synchronous control-based broadband impedance model of the network-constructed converter; carrying out per-unit processing on the electrical parameters of the network construction type converter to obtain per-unit electrical parameters; inputting the control parameters and the per-unit electrical parameters of the network construction type converter into a broadband impedance model of the network construction type converter, and calculating broadband impedance amplitude characteristics of the network construction type converter; and analyzing the grid-connected stability of the network construction type converter according to the broadband impedance amplitude characteristics, and determining the grid-connected stability of the network construction type converter.

Description

Technical Field

[0001] The present invention relates to the technical field of electrical equipment and electrical engineering, and more specifically, to a grid-connected stability analysis method of a grid-connected converter based on virtual synchronous control. Background Art

[0002] In order to ensure the stable operation of new power systems with high penetration of power electronics in the future (even 100% penetration), some of the converters need to be controlled as voltage sources rather than current sources. By drawing on the physical mechanism of synchronous generators, different scholars have proposed the concept of grid-type converters from different perspectives at different times. Although the specific implementation of the control architecture of grid-type converters varies in details in different literatures, they all follow the same essence, namely: 1) Control the converter as a voltage source rather than a current source; 2) Synchronize by controlling the converter's own output power (or DC voltage) rather than just sampling the external AC grid voltage. The above two core control ideas ensure that the grid-type converter can build the AC side output voltage by itself without relying on the external AC system. Therefore, the grid-type converter can operate in an isolated island or be connected to an extremely weak grid.

[0003] Due to the above advantages, the application of grid-type converters in power systems has received widespread attention in recent years. In addition to a small number of pilot projects, some countries have begun to plan large-scale engineering applications of grid-type converters. Unlike the grid-following new energy control strategy, the grid-type control strategy can establish voltage and frequency by itself and has less dependence on the grid. Even in an extremely weak grid with a short circuit ratio (SCR) close to 1, the grid-type converter can still maintain stable operation. With its good weak grid stability, grid-type control has gradually been applied on site. With the access of grid-type converters, the oscillation characteristics of new energy stations will also change. How to accurately analyze the system stability after the grid-type converter is connected to the grid has become a technical problem that needs to be solved urgently. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a grid-connected stability analysis method for a grid-connected converter based on virtual synchronous control.

[0005] According to one aspect of the present invention, a method for analyzing grid-connected stability of a grid-connected converter based on virtual synchronous control is provided, comprising:

[0006] Construct a broadband impedance model of grid-connected converter based on virtual synchronous control;

[0007] Normalize the electrical parameters of the grid-type converter to obtain normalized electrical parameters;

[0008] The control parameters and normalized electrical parameters of the grid-type converter are input into the broadband impedance model of the grid-type converter to calculate the broadband impedance amplitude characteristics of the grid-type converter;

[0009] The grid-connected stability of the grid-connected converter is analyzed according to the broadband impedance amplitude characteristics, and the grid-connected stability of the grid-connected converter is determined.

[0010] Optionally, a broadband impedance model of a grid-connected converter based on virtual synchronous control is constructed, including:

[0011] Construct the active power disturbance expression and reactive power disturbance expression of grid-connected converter;

[0012] When the grid-type converter adopts virtual synchronous control, the expression of virtual phase angle disturbance component is constructed according to the expression of active power disturbance quantity;

[0013] In the reactive power control link of the grid-type converter, the virtual voltage disturbance component expression is constructed according to the reactive power disturbance expression;

[0014] Constructing a virtual voltage disturbance component expression according to a virtual voltage disturbance component expression, an active power disturbance quantity expression, and a reactive power disturbance quantity expression;

[0015] Construct the circuit relationship expression between the grid connection point voltage and the converter voltage:

[0016] According to the circuit relationship expression and the virtual voltage disturbance component expression, the voltage component expression in the control coordinate system is constructed;

[0017] According to the voltage component expression in the control coordinate system, the equivalent impedance expression of the grid-type converter in the control coordinate system is constructed;

[0018] According to the transformation method of voltage phasor and current phasor constructed by virtual phase angle disturbance component expression in control coordinate system and synchronous coordinate system, the transformation relationship between control coordinate system and synchronous coordinate system is constructed;

[0019] According to the transformation relationship between the control coordinate system and the synchronous coordinate system and the equivalent impedance expression of the grid-type converter, a broadband impedance model of the grid-type converter is constructed.

[0020] Optionally, the equivalent impedance expression of the grid-type converter in the control coordinate system is:

[0021]

[0022] In the formula, Z dq is the equivalent impedance of the grid-type converter, G i =K pi +K ii / s is the inner loop PI control link, K pi is the voltage loop proportional coefficient, K ii is the voltage loop integral coefficient, L is the series inductance, G v =K pv +K iv / s is the outer loop PI control link, K pv is the PI control proportional coefficient, K iv is the PI control integral coefficient, i d0 is the d-axis component of the steady-state output current of the grid-type converter in the dq coordinate system, s is the Laplace operator, D P is the virtual damping coefficient.

[0023] Optionally, the expression of the transformation relationship between the control coordinate system and the synchronization coordinate system is:

[0024]

[0025] in,

[0026]

[0027] In the formula, Δu d ,Δu q are the voltage d-axis and q-axis components in the control coordinate system, Δi d , Δi q They are the d-axis and q-axis components of the current in the control coordinate system, Δu x , Δu y are the voltage d-axis and q-axis components in the synchronous coordinate system, Δi x , Δi y are the d-axis and q-axis components of the current in the synchronous coordinate system, K f is the active frequency modulation coefficient, T J is the virtual inertia coefficient, u d0 It is the d-axis component of the steady-state value of the terminal voltage in the dq coordinate system of the grid-type converter.

[0028] Optionally, the expression of the broadband impedance model of the grid-type converter is:

[0029]

[0030] In the formula, Z xy It is the broadband impedance of the grid-type converter.

[0031] According to another aspect of the present invention, a grid-connected stability analysis device for a grid-connected converter based on virtual synchronous control is provided, comprising:

[0032] A construction module for constructing a broadband impedance model of a grid-connected converter based on virtual synchronous control;

[0033] A per-unit standardization module is used to standardize the electrical parameters of the grid-type converter to obtain the per-unit standardized electrical parameters;

[0034] A calculation module, used for inputting the control parameters and normalized electrical parameters of the grid-type converter into the broadband impedance model of the grid-type converter, and calculating the broadband impedance amplitude characteristics of the grid-type converter;

[0035] The analysis module is used to analyze the grid-connected stability of the grid-connected converter according to the broadband impedance amplitude characteristic, and determine the grid-connected stability of the grid-connected converter.

[0036] According to another aspect of the present invention, a computer-readable storage medium is provided, wherein the storage medium stores a computer program, and the computer program is used to execute the method described in any one of the above aspects of the present invention.

[0037] According to another aspect of the present invention, an electronic device is provided, comprising: a processor; a memory for storing instructions executable by the processor; the processor is configured to read the executable instructions from the memory and execute the instructions to implement the method described in any one of the above aspects of the present invention.

[0038] Therefore, the broadband impedance modeling method of the grid-type converter based on virtual synchronous control proposed in the present invention can characterize the impedance characteristics of the grid-type converter in a wide frequency band, has high reliability and practicality, and solves the modeling problem in the grid-connected stability analysis of the grid-type converter. The model can reflect the amplitude-frequency characteristics of the grid-type converter in a wide frequency band, and includes the differences and influences of the control and electrical structure of each link. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] A more complete understanding of exemplary embodiments of the present invention may be obtained by referring to the following drawings:

[0040] Figure 1 It is a flow chart of a grid-connected stability analysis method of a grid-connected converter based on virtual synchronous control provided by an exemplary embodiment of the present invention;

[0041] Figure 2 It is a schematic diagram of positive sequence impedance characteristics of a grid-connected converter based on virtual synchronous control provided by an exemplary embodiment of the present invention;

[0042] Figure 3 It is a schematic diagram of negative sequence impedance characteristics of a grid-connected converter based on virtual synchronous control provided by an exemplary embodiment of the present invention;

[0043] Figure 4 It is a structural schematic diagram of a grid-connected stability analysis device for a grid-connected converter based on virtual synchronous control provided by an exemplary embodiment of the present invention;

[0044] Figure 5 This is a structure of an electronic device provided by an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0045] Below, the exemplary embodiments according to the present invention will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments of the present invention, and it should be understood that the present invention is not limited to the exemplary embodiments described here.

[0046] It should be noted that the relative arrangement of components and steps, the numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise.

[0047] Those skilled in the art can understand that the terms "first" and "second" in the embodiments of the present invention are only used to distinguish different steps, devices or modules, etc., and neither represent any specific technical meaning nor indicate the necessary logical order between them.

[0048] It should also be understood that, in the embodiments of the present invention, “plurality” may refer to two or more than two, and “at least one” may refer to one, two or more than two.

[0049] It should also be understood that any component, data or structure mentioned in the embodiments of the present invention can generally be understood as one or more, unless explicitly limited or otherwise indicated in the context.

[0050] In addition, the term "and / or" in the present invention is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in the present invention generally indicates that the associated objects before and after are in an "or" relationship.

[0051] It should also be understood that the description of the various embodiments of the present invention focuses on the differences between the various embodiments, and the same or similar aspects thereof can be referenced to each other, and for the sake of brevity, they will not be described one by one.

[0052] At the same time, it should be understood that for the convenience of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship.

[0053] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

[0054] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0055] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0056] Embodiments of the present invention can be applied to electronic devices such as terminal devices, computer systems, servers, etc., which can operate with many other general or special computing system environments or configurations. Examples of well-known terminal devices, computing systems, environments and / or configurations suitable for use with electronic devices such as terminal devices, computer systems, servers, etc. include, but are not limited to: personal computer systems, server computer systems, thin clients, thick clients, handheld or laptop devices, microprocessor-based systems, set-top boxes, programmable consumer electronics, network personal computers, small computer systems, large computer systems, and distributed cloud computing technology environments including any of the above systems, etc.

[0057] Electronic devices such as terminal devices, computer systems, servers, etc. can be described in the general context of computer system executable instructions (such as program modules) executed by computer systems. Generally, program modules can include routines, programs, object programs, components, logic, data structures, etc., which perform specific tasks or implement specific abstract data types. Computer systems / servers can be implemented in a distributed cloud computing environment, where tasks are performed by remote processing devices linked through a communication network. In a distributed cloud computing environment, program modules can be located on local or remote computing system storage media including storage devices.

[0058] Exemplary Methods

[0059] Figure 1 1 is a flow chart of a method for analyzing grid-connected stability of a grid-connected converter based on virtual synchronous control provided by an exemplary embodiment of the present invention. This embodiment can be applied to electronic devices, such as Figure 1 As shown, the grid-connected stability analysis method 100 of a grid-connected converter based on virtual synchronous control includes the following steps:

[0060] Step 101, constructing a broadband impedance model of a grid-connected converter based on virtual synchronous control;

[0061] Step 102, normalizing the electrical parameters of the grid-connected converter to obtain normalized electrical parameters;

[0062] Step 103, inputting the control parameters and normalized electrical parameters of the grid-type converter into the broadband impedance model of the grid-type converter to calculate the broadband impedance amplitude characteristics of the grid-type converter;

[0063] Step 104 , analyzing the grid-connected stability of the grid-connected converter according to the broadband impedance amplitude characteristic, and determining the grid-connected stability of the grid-connected converter.

[0064] An accurate impedance model is the basis for oscillation analysis using impedance analysis. The present invention proposes a broadband impedance modeling method for a grid-connected converter based on virtual synchronous control, which can be used for system stability assessment after the grid-connected converter is connected to the grid.

[0065] The active power and reactive power output by the grid-connected converter can be expressed as:

[0066]

[0067] Among them, u d 、u q are the d-axis and q-axis components of the terminal voltage in the dq coordinate system of the grid-connected converter respectively; i d 、i q They are respectively the d-axis and q-axis components of the output current of the grid-type converter in the dq coordinate system.

[0068] The power disturbance in formula (1) can be expressed as:

[0069]

[0070] Among them, u d0 、u q0 are the d-axis and q-axis components of the steady-state voltage at the machine end in the dq coordinate system of the grid-connected converter; i d0 、i q0 They are the d-axis and q-axis components of the steady-state output current of the grid-type converter in the dq coordinate system.

[0071] When performing dq conversion, the d-axis voltage is used as the orientation, so u q0 =0,i q0 = 0, while ignoring the small signal multiplication term Δu q Δi q and Δu d Δi q , then:

[0072]

[0073] When the grid-type converter adopts virtual synchronous control, its active power control link generates a virtual angular frequency according to ΔP:

[0074]

[0075] Among them, T J is the virtual inertia coefficient; D P is the virtual damping coefficient; K fis the active frequency modulation coefficient; Δω is the virtual angular frequency disturbance component.

[0076] The expression of Δω can be obtained from the formula:

[0077]

[0078] After integration, the virtual phase angle disturbance component Δθ is obtained as:

[0079]

[0080] The reactive power control link of the grid-connected converter generates a virtual voltage ΔE according to ΔQ:

[0081] ΔE=-D q ΔQ=-D q (Δu q i d0 -u d0 Δi q ) (7)

[0082] Among them, D q is the q-axis damping coefficient.

[0083] The disturbance component Δu of the virtual voltage disturbance in the dq coordinate system d1 ,Δu q1 Respectively expressed as

[0084]

[0085] Then the voltage is controlled by the PI control link to generate the current reference value, and its disturbance component Δi in the dq coordinate system is dr ,Δi qr Respectively expressed as:

[0086] Δi dr =G v (Δu d1 -Δu d )

[0087] Δi qr =G v (Δu q1 -Δu q ) (9)

[0089] Among them, G v =K pv +K iv / s is the PI control link, K pv is the current loop proportionality coefficient, K iv is the current loop integration coefficient.

[0090] According to the current reference value, the voltage reference value is generated through the PI control link, and its disturbance component Δu in the dq coordinate system is dr ,Δu qr Respectively expressed as:

[0091]

[0092] Among them, G i =K pi +K ii / s is the PI control link, K pi is the voltage loop proportional coefficient, K ii is the voltage loop integral coefficient, L is the series inductance, and ω0 is the synchronous speed.

[0093] Combining equations (3) to (10), we can obtain:

[0094]

[0095] Assuming that the converter voltage can track the control voltage reference value with error, the circuit relationship between the grid connection point voltage and the converter voltage is:

[0096]

[0097] Combining equation (11) and equation (12), we can get:

[0098]

[0099] Then the equivalent impedance of the grid-type converter in the control coordinate system can be expressed as:

[0100]

[0101] The grid-connected converter system contains two coordinate systems: the control coordinate system (dq coordinate system) rotating at the speed ω measured by the phase-locked loop and the synchronous coordinate system (xy coordinate system) rotating at the synchronous speed ω0. In steady state, the dq coordinate system coincides with the xy coordinate system. After being disturbed, the angle between the x-axis of the synchronous coordinate system and the d-axis of the control coordinate system is recorded as θ. The conversion method of the voltage phasor and the current phasor in the control coordinate system and the synchronous coordinate system is:

[0102]

[0103] Wherein, θ0 is the angle between the dq coordinate system and the abc coordinate system during steady-state operation, θ0 = 0. Δu x ,Δu y are the voltage d-axis and q-axis components in the synchronous coordinate system, Δu d ,Δu q are the d-axis and q-axis components of the voltage in the control coordinate system.

[0104] From equations (15) and (16), we can get the relationship between the control coordinate system and the synchronization coordinate system:

[0105]

[0106] in,

[0107]

[0108] Then we have:

[0109]

[0110] Combining equations (17) and (18), we can obtain the broadband impedance of the grid-type converter in the synchronous coordinate system:

[0111]

[0112] Based on the detailed parameters of the grid-connected converter shown in Table 1, the modeling method proposed in the present invention is adopted.

[0113] The broadband impedance characteristics of the grid-type converter based on virtual synchronous control can be obtained as follows: Figure 2-Figure 3 shown.

[0114] Table 1 Detailed parameters of grid-connected converter

[0115]

[0116] Therefore, the broadband impedance modeling method of the grid-type converter based on virtual synchronous control proposed in the present invention can characterize the impedance characteristics of the grid-type converter in a wide frequency band, has high reliability and practicality, and solves the modeling problem in the grid-connected stability analysis of the grid-type converter. The model can reflect the amplitude-frequency characteristics of the grid-type converter in a wide frequency band, and includes the differences and influences of the control and electrical structure of each link.

[0117] The model proposed in the present invention can be applied to the analysis of the wide-band oscillation stability of the system under the grid-connected grid-type converter using the impedance method. It is based on the typical and most widely used virtual synchronous control, and each control link adopts a relatively mature control method. Therefore, the modeling method has a certain versatility.

[0118] Exemplary Devices

[0119] Figure 4 FIG. 1 is a schematic diagram of a structure of a grid-connected converter stability analysis device based on virtual synchronous control provided by an exemplary embodiment of the present invention. Figure 4 As shown, the device 400 includes:

[0120] A construction module 410 is used to construct a broadband impedance model of a grid-connected converter based on virtual synchronous control;

[0121] The per-unit normalization module 420 is used to normalize the electrical parameters of the grid-connected converter to obtain the normalized electrical parameters;

[0122] The calculation module 430 is used to input the control parameters and the normalized electrical parameters of the grid-type converter into the broadband impedance model of the grid-type converter to calculate the broadband impedance amplitude characteristics of the grid-type converter;

[0123] The analysis module 440 is used to analyze the grid-connected stability of the grid-connected converter according to the broadband impedance amplitude characteristic, and determine the grid-connected stability of the grid-connected converter.

[0124] Optionally, the construction module 410 includes:

[0125] Construct the active power disturbance expression and reactive power disturbance expression of grid-connected converter;

[0126] When the grid-type converter adopts virtual synchronous control, the expression of virtual phase angle disturbance component is constructed according to the expression of active power disturbance quantity;

[0127] In the reactive power control link of the grid-type converter, the virtual voltage disturbance component expression is constructed according to the reactive power disturbance expression;

[0128] Constructing a virtual voltage disturbance component expression according to a virtual voltage disturbance component expression, an active power disturbance quantity expression, and a reactive power disturbance quantity expression;

[0129] Construct the circuit relationship expression between the grid connection point voltage and the converter voltage:

[0130] According to the circuit relationship expression and the virtual voltage disturbance component expression, the voltage component expression in the control coordinate system is constructed;

[0131] According to the voltage component expression in the control coordinate system, the equivalent impedance expression of the grid-type converter in the control coordinate system is constructed;

[0132] According to the transformation method of voltage phasor and current phasor constructed by virtual phase angle disturbance component expression in control coordinate system and synchronous coordinate system, the transformation relationship between control coordinate system and synchronous coordinate system is constructed;

[0133] According to the transformation relationship between the control coordinate system and the synchronous coordinate system and the equivalent impedance expression of the grid-type converter, a broadband impedance model of the grid-type converter is constructed.

[0134] Optionally, the equivalent impedance expression of the grid-type converter in the control coordinate system is:

[0135]

[0136] In the formula, Z dq is the equivalent impedance of the grid-type converter, G i =K pi +K ii / s is the inner loop PI control link, K pi is the voltage loop proportional coefficient, K ii is the voltage loop integral coefficient, L is the series inductance, G v =K pv +K iv / s is the outer loop PI control link, K pv is the PI control proportional coefficient, K iv is the PI control integral coefficient, i d0 is the d-axis component of the steady-state output current of the grid-type converter in the dq coordinate system, s is the Laplace operator, D P is the virtual damping coefficient.

[0137] Optionally, the expression of the transformation relationship between the control coordinate system and the synchronization coordinate system is:

[0138]

[0139] in,

[0140]

[0141] In the formula, Δu d ,Δu q are the voltage d-axis and q-axis components in the control coordinate system, Δi d , Δi q They are the d-axis and q-axis components of the current in the control coordinate system, Δu x , Δu y are the voltage d-axis and q-axis components in the synchronous coordinate system, Δi x , Δi y are the d-axis and q-axis components of the current in the synchronous coordinate system, K f is the active frequency modulation coefficient, T J is the virtual inertia coefficient, u d0 It is the d-axis component of the steady-state value of the terminal voltage in the dq coordinate system of the grid-type converter.

[0142] Optionally, the expression of the broadband impedance model of the grid-type converter is:

[0143]

[0144] In the formula, Z xy It is the broadband impedance of the grid-type converter.

[0145] Exemplary Electronic Devices

[0146] Figure 5 This is a structure of an electronic device provided by an exemplary embodiment of the present invention. Figure 5 As shown, the electronic device 50 includes one or more processors 51 and a memory 52 .

[0147] The processor 51 may be a central processing unit (CPU) or other forms of processing units having data processing capabilities and / or instruction execution capabilities, and may control other components in the electronic device to perform desired functions.

[0148] The memory 52 may include one or more computer program products, which may include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. The volatile memory may include, for example, random access memory (RAM) and / or cache memory (cache), etc. The non-volatile memory may include, for example, read-only memory (ROM), hard disk, flash memory, etc. One or more computer program instructions may be stored on the computer-readable storage medium, and the processor 51 may run the program instructions to implement the methods of the software programs of the various embodiments of the present invention described above and / or other desired functions. In one example, the electronic device may also include: an input device 53 and an output device 54, which are interconnected via a bus system and / or other forms of connection mechanisms (not shown).

[0149] In addition, the input device 53 may also include, for example, a keyboard, a mouse, etc.

[0150] The output device 54 can output various information to the outside. The output device 54 can include, for example, a display, a speaker, a printer, a communication network and a remote output device connected thereto.

[0151] Of course, to simplify, Figure 5 Only some of the components related to the present invention in the electronic device are shown, and components such as a bus, an input / output interface, etc. are omitted. In addition, the electronic device may further include any other appropriate components according to specific application conditions.

[0152] Exemplary computer program products and computer-readable storage media

[0153] In addition to the above-mentioned methods and devices, an embodiment of the present invention may also be a computer program product, which includes computer program instructions, which, when executed by a processor, enable the processor to execute the steps of the method according to various embodiments of the present invention described in the above-mentioned "Exemplary Method" section of this specification.

[0154] The computer program product may be written in any combination of one or more programming languages ​​to write program code for performing the operations of the embodiments of the present invention, including object-oriented programming languages ​​such as Java, C++, etc., and conventional procedural programming languages ​​such as "C" or similar programming languages. The program code may be executed entirely on the user computing device, partially on the user device, as a separate software package, partially on the user computing device and partially on a remote computing device, or entirely on a remote computing device or server.

[0155] In addition, an embodiment of the present invention may also be a computer-readable storage medium having computer program instructions stored thereon, which, when executed by a processor, enable the processor to execute the steps of the method according to various embodiments of the present invention described in the above “Exemplary Method” section of this specification.

[0156] The computer readable storage medium can adopt any combination of one or more readable media. The readable medium can be a readable signal medium or a readable storage medium. The readable storage medium can include, for example, but is not limited to, a system, system or device of electricity, magnetism, light, electromagnetic, infrared, or semiconductor, or any combination of the above. More specific examples (non-exhaustive list) of readable storage media include: an electrical connection with one or more wires, a portable disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above.

[0157] The basic principle of the present invention is described above in conjunction with specific embodiments. However, it should be pointed out that the advantages, strengths, effects, etc. mentioned in the present invention are only examples and not limitations, and it cannot be considered that these advantages, strengths, effects, etc. must be possessed by each embodiment of the present invention. In addition, the specific details disclosed above are only for the purpose of illustration and facilitation of understanding, rather than limitation, and the above details do not limit the present invention to being implemented by adopting the above specific details.

[0158] Each embodiment in this specification is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the system embodiment, since it basically corresponds to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0159] The block diagrams of the devices, systems, equipment, and systems involved in the present invention are only illustrative examples and are not intended to require or imply that they must be connected, arranged, and configured in the manner shown in the block diagram. As will be appreciated by those skilled in the art, these devices, systems, equipment, and systems can be connected, arranged, and configured in any manner. Words such as "including", "comprising", "having", etc. are open words, referring to "including but not limited to", and can be used interchangeably with them. The words "or" and "and" used here refer to the words "and / or" and can be used interchangeably with them, unless the context clearly indicates otherwise. The word "such as" used here refers to the phrase "such as but not limited to", and can be used interchangeably with it.

[0160] The method and system of the present invention may be implemented in many ways. For example, the method and system of the present invention may be implemented by software, hardware, firmware or any combination of software, hardware, firmware. The above order of steps for the method is only for illustration, and the steps of the method of the present invention are not limited to the order specifically described above, unless otherwise specifically stated. In addition, in some embodiments, the present invention may also be implemented as a program recorded in a recording medium, which includes machine-readable instructions for implementing the method according to the present invention. Thus, the present invention also covers a recording medium storing a program for executing the method according to the present invention.

[0161] It should also be noted that in the system, device and method of the present invention, each component or each step can be decomposed and / or recombined. These decompositions and / or recombinations should be regarded as equivalent schemes of the present invention. The above description of the disclosed aspects is provided to enable any technician in the field to make or use the present invention. Various modifications to these aspects are very obvious to those skilled in the art, and the general principles defined here can be applied to other aspects without departing from the scope of the present invention. Therefore, the present invention is not intended to be limited to the aspects shown here, but in accordance with the widest range consistent with the principles and novel features disclosed here.

[0162] The above description has been given for the purpose of illustration and description. In addition, this description is not intended to limit the embodiments of the present invention to the forms disclosed herein. Although a number of example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations thereof.

Claims

1. A grid-connected stability analysis method for a grid-connected converter based on virtual synchronous control, characterized in that: include: Construct a broadband impedance model of grid-connected converter based on virtual synchronous control; Normalize the electrical parameters of the grid-type converter to obtain normalized electrical parameters; Inputting the control parameters of the grid-type converter and the normalized electrical parameters into the broadband impedance model of the grid-type converter to calculate the broadband impedance amplitude characteristics of the grid-type converter; The grid-connected stability of the grid-connected converter is analyzed according to the broadband impedance amplitude characteristic to determine the grid-connected stability of the grid-connected converter.

2. The method according to claim 1, characterized in that: Construct a broadband impedance model of grid-connected converter based on virtual synchronous control, including: Constructing an active power disturbance expression and a reactive power disturbance expression of the grid-connected converter; When the grid-type converter adopts virtual synchronous control, constructing a virtual phase angle disturbance component expression according to the active power disturbance expression; In the reactive power control link of the grid-type converter, a virtual voltage disturbance component formal expression is constructed according to the reactive power disturbance expression; Constructing a virtual voltage disturbance component expression according to the virtual voltage disturbance component expression, the active power disturbance amount expression, and the reactive power disturbance amount expression; Construct the circuit relationship expression between the grid connection point voltage and the converter voltage: Constructing a voltage component expression in a control coordinate system according to the circuit relationship expression and the virtual voltage disturbance component expression; According to the voltage component expression in the control coordinate system, an equivalent impedance expression of the grid-type converter in the control coordinate system is constructed; According to the transformation method of the voltage phasor and the current phasor constructed by the virtual phase angle disturbance component expression in the control coordinate system and the synchronous coordinate system, a transformation relationship between the control coordinate system and the synchronous coordinate system is constructed; According to the transformation relationship between the control coordinate system and the synchronization coordinate system and the equivalent impedance expression of the grid-type converter, a broadband impedance model of the grid-type converter is constructed.

3. The method according to claim 2, characterized in that The equivalent impedance expression of the grid-type converter in the control coordinate system is: In the formula, Z dq is the equivalent impedance of the grid-type converter, G i =K pi +K ii / s is the inner loop PI control link, K pi is the voltage loop proportional coefficient, K ii is the voltage loop integral coefficient, L is the series inductance, G v =K pv +K iv / s is the outer loop PI control link, K pv is the PI control proportional coefficient, K iv is the PI control integral coefficient, i d0 is the d-axis component of the steady-state output current of the grid-type converter in the dq coordinate system, s is the Laplace operator, D P is the virtual damping coefficient.

4. The method according to claim 3, characterized in that The expression of the transformation relationship between the control coordinate system and the synchronization coordinate system is: in, In the formula, Δu d ,Δu q are the voltage d-axis and q-axis components in the control coordinate system, Δi d , Δi q They are the d-axis and q-axis components of the current in the control coordinate system, Δu x , Δu y are the voltage d-axis and q-axis components in the synchronous coordinate system, Δi x , Δi y are the d-axis and q-axis components of the current in the synchronous coordinate system, K f is the active frequency modulation coefficient, T J is the virtual inertia coefficient, u d0 It is the d-axis component of the steady-state value of the terminal voltage in the dq coordinate system of the grid-type converter.

5. The method according to claim 4, characterized in that The expression of the broadband impedance model of the grid-type converter is: In the formula, Z xy It is the broadband impedance of the grid-type converter.

6. A grid-connected stability analysis device for a grid-connected converter based on virtual synchronous control, characterized in that: include: A construction module for constructing a broadband impedance model of a grid-connected converter based on virtual synchronous control; A per-unit standardization module is used to standardize the electrical parameters of the grid-type converter to obtain the per-unit standardized electrical parameters; A calculation module, used for inputting the control parameters of the grid-type converter and the normalized electrical parameters into the broadband impedance model of the grid-type converter to calculate the broadband impedance amplitude characteristics of the grid-type converter; The analysis module is used to analyze the grid-connected stability of the grid-connected converter according to the broadband impedance amplitude characteristic, and determine the grid-connected stability of the grid-connected converter.

7. The device according to claim 6, characterized in that Building blocks, including: Constructing an active power disturbance expression and a reactive power disturbance expression of the grid-connected converter; When the grid-type converter adopts virtual synchronous control, constructing a virtual phase angle disturbance component expression according to the active power disturbance expression; In the reactive power control link of the grid-type converter, a virtual voltage disturbance component formal expression is constructed according to the reactive power disturbance expression; Constructing a virtual voltage disturbance component expression according to the virtual voltage disturbance component expression, the active power disturbance amount expression, and the reactive power disturbance amount expression; Construct the circuit relationship expression between the grid connection point voltage and the converter voltage: Constructing a voltage component expression in a control coordinate system according to the circuit relationship expression and the virtual voltage disturbance component expression; According to the voltage component expression in the control coordinate system, an equivalent impedance expression of the grid-type converter in the control coordinate system is constructed; According to the transformation method of the voltage phasor and the current phasor constructed by the virtual phase angle disturbance component expression in the control coordinate system and the synchronous coordinate system, a transformation relationship between the control coordinate system and the synchronous coordinate system is constructed; According to the transformation relationship between the control coordinate system and the synchronization coordinate system and the equivalent impedance expression of the grid-type converter, a broadband impedance model of the grid-type converter is constructed.

8. The device according to claim 7, characterized in that The equivalent impedance expression of the grid-type converter in the control coordinate system is: In the formula, Z dq is the equivalent impedance of the grid-type converter, G i =K pi +K ii / s is the inner loop PI control link, K pi is the voltage loop proportional coefficient, K ii is the voltage loop integral coefficient, L is the series inductance, G v =K pv +K iv / s is the outer loop PI control link, K pv is the PI control proportional coefficient, K iv is the PI control integral coefficient, i d0 is the d-axis component of the steady-state output current of the grid-type converter in the dq coordinate system, s is the Laplace operator, D P is the virtual damping coefficient.

9. The device according to claim 8, characterized in that The expression of the transformation relationship between the control coordinate system and the synchronization coordinate system is: in, In the formula, Δu d ,Δu q are the voltage d-axis and q-axis components in the control coordinate system, Δi d , Δi q They are the d-axis and q-axis components of the current in the control coordinate system, Δu x , Δu y are the voltage d-axis and q-axis components in the synchronous coordinate system, Δi x , Δi y are the d-axis and q-axis components of the current in the synchronous coordinate system, K f is the active frequency modulation coefficient, T J is the virtual inertia coefficient, u d0 It is the d-axis component of the steady-state value of the terminal voltage in the dq coordinate system of the grid-type converter.

10. The device according to claim 9, characterized in that The expression of the broadband impedance model of the grid-type converter is: In the formula, Z xy It is the broadband impedance of the grid-type converter.

11. A computer-readable storage medium, characterized in that: The storage medium stores a computer program, and the computer program is used to execute the method according to any one of claims 1 to 5.

12. An electronic device, characterized in that: The electronic device comprises: processor; a memory for storing instructions executable by the processor; The processor is used to read the executable instructions from the memory and execute the instructions to implement the method described in any one of claims 1 to 5.

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