Bidirectional virtual impedance adding method and device of power system and medium

Abstract

The invention discloses a bidirectional virtual impedance adding method and device of a power system and a medium. The method comprises the steps that operation electric quantity data of a preset key measuring point of the electric power system are collected in real time, and the operation electric quantity data comprise voltage and current; judging whether the power system has an overcurrent risk or not in real time according to the operation electric quantity data; and under the condition that the power system has no overcurrent risk, adding forward virtual impedance to the power system, otherwise, adding reverse virtual impedance to the power system.

Description

Technical Field

[0001] The present invention relates to the technical field of converter optimization control, and more specifically, to a method, device and medium for adding bidirectional virtual impedance to an electric power system. Background Art

[0002] my country's new power system presents the "double high" characteristics of high proportion of renewable energy and high proportion of power electronic equipment, with reduced system inertia and weakened grid strength. In recent years, grid-forming (GFM) control strategies that can be applied to weak grid environments have become the research focus of related fields. Typical grid-forming control strategies include droop control, virtual synchronous generator control (VSG), virtual oscillator control (VOC), etc. However, the virtual synchronous generator control strategy also includes droop control links, and virtual oscillator control has been proven to have steady-state droop characteristics. Therefore, even in the current rapid development of various new control technologies, droop control still needs to be analyzed and re-recognized. Grid-forming control technologies such as droop control have a strong dependence on virtual impedance. Especially in actual engineering, if grid-forming control wants to have better performance, it is inseparable from the role of virtual impedance technology in power decoupling, power distribution accuracy improvement, circulating current suppression, overcurrent suppression, etc. The so-called virtual impedance is a virtual impedance that is added to the control link by utilizing the characteristic relationship between voltage and current. It will not cause additional losses to the power system, nor will it cause additional increases in project costs or equipment volume. Regarding the mechanism and design methods of virtual impedance in droop control, certain research results have been achieved, such as virtual negative impedance and virtual inductance. However, there are still technical problems in the prior art that the virtual impedance design method and system cannot simultaneously suppress overcurrent and support voltage. Summary of the invention

[0003] In view of the deficiencies in the prior art, the present invention provides a method, device and medium for adding bidirectional virtual impedance to an electric power system.

[0004] According to one aspect of the present invention, a method for adding bidirectional virtual impedance to a power system is provided, comprising:

[0005] Real-time collection of operating power data of preset key measuring points of the power system, including voltage and current;

[0006] Determine in real time whether there is an overcurrent risk in the power system based on the operating power data;

[0007] When there is no overcurrent risk in the power system, a forward virtual impedance is added to the power system, otherwise a reverse virtual impedance is added to the power system.

[0008] Optionally, key measuring points include: converter terminals, grid connection points or public connection points, and related buses in the grid.

[0009] Optionally, the criterion for overcurrent risk is:

[0010] When the voltage of the operating power data exceeds a preset voltage threshold or the current exceeds a preset current threshold, there is an overcurrent risk; otherwise, there is no overcurrent risk.

[0011] Optionally, the forward virtual impedance is added to the power system in the form of a virtual external reactance, and the current direction on the forward virtual impedance is from the valve side to the grid side. The larger the virtual impedance, the larger the converter terminal voltage, and the larger the converter output reactive power. The smaller the virtual impedance, the smaller the converter terminal voltage, and the smaller the converter output reactive power.

[0012] Optionally, the reverse virtual impedance is added to the system in the form of an equivalent internal reactance on the source side. The current direction on the reverse virtual impedance is from the grid side to the valve side. The larger the virtual impedance, the smaller the converter machine-end voltage, and the smaller the converter output reactive power. The smaller the virtual impedance, the larger the converter machine-end voltage, and the larger the converter output reactive power.

[0013] According to another aspect of the present invention, there is provided a bidirectional virtual impedance adding device for an electric power system, comprising:

[0014] A collection module is used to collect the operating power data of preset key measuring points of the power system in real time, where the operating power data includes voltage and current;

[0015] A judgment module is used to judge whether there is an overcurrent risk in the power system in real time based on the operating power data;

[0016] The adding module is used to add a forward virtual impedance to the power system when there is no overcurrent risk in the power system, otherwise, a reverse virtual impedance is added to the power system.

[0017] 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.

[0018] 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.

[0019] Therefore, the present invention proposes a method for adding bidirectional virtual impedance. When the system is operating normally, the current flowing through the virtual impedance is a positive current flowing from the valve side to the grid side, and a positive virtual impedance, i.e., a virtual external reactance, is introduced; and when an overcurrent fault occurs in the system, the current flowing through the virtual impedance is reversed, from the grid side to the valve side, and a reverse virtual impedance is introduced. In addition to being realized by changing the direction of the current flowing through it, bidirectional virtual impedance can also be realized by modifying the positive and negative values ​​of the virtual impedance, which effectively improves its grid voltage support capability. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] A more complete understanding of exemplary embodiments of the present invention may be obtained by referring to the following drawings:

[0021] Figure 1 It is a flow chart of a method for adding bidirectional virtual impedance to a power system provided by an exemplary embodiment of the present invention;

[0022] Figure 2 is a control block diagram of adding reverse virtual impedance provided by an exemplary embodiment of the present invention;

[0023] Figure 3 It is a schematic diagram of an equivalent simulation model of a grid-connected converter using a single-machine load system model provided by an exemplary embodiment of the present invention;

[0024] Figure 4 is a schematic diagram of simulation results of adding a traditional virtual impedance provided by an exemplary embodiment of the present invention;

[0025] Figure 5a and Figure 5b It is a control logic diagram of a bidirectional virtual impedance for changing the current direction and the positive and negative values ​​of the virtual impedance provided by an exemplary embodiment of the present invention;

[0026] Figure 6 is a schematic diagram of reactive power-voltage waveforms at the converter machine end provided by an exemplary embodiment of the present invention;

[0027] Figure 7 is another flow chart of a method for adding bidirectional virtual impedance to a power system provided by an exemplary embodiment of the present invention;

[0028] Figure 8a-8c It is a schematic diagram of simulation results of a power system provided by an exemplary embodiment of the present invention without adding any virtual impedance to the system, after adding a traditional reverse virtual impedance, and after adding a forward virtual impedance;

[0029] Fig. 9 It is a schematic diagram of a model of a two-grid-type converter parallel-connected load-operating system provided by an exemplary embodiment of the present invention;

[0030] Fig.10a and Fig.10b It is a schematic diagram of the current output waveform of the converter under the working condition without adding virtual impedance and after adding virtual impedance provided by an exemplary embodiment of the present invention;

[0031] Fig.11 It is a schematic diagram of a virtual impedance link application structure of an electric power system provided by an exemplary embodiment of the present invention;

[0032] Fig.12 is a structural schematic diagram of a bidirectional virtual impedance adding device for a power system provided by an exemplary embodiment of the present invention;

[0033] Fig.13 This is a structure of an electronic device provided by an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0034] 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.

[0035] It should be noted that the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] Exemplary Methods

[0048] Figure 1 FIG. 1 is a flow chart of a method for adding bidirectional virtual impedance to an electric power system provided by an exemplary embodiment of the present invention. This embodiment can be applied to electronic devices, such as Figure 1 As shown, the bidirectional virtual impedance adding method 100 of the power system includes the following steps:

[0049] Step 101, collecting the operating power data of preset key measuring points of the power system in real time, wherein the operating power data includes voltage and current;

[0050] Step 102, judging in real time whether there is an overcurrent risk in the power system according to the operating power data;

[0051] Step 103: When there is no overcurrent risk in the power system, a forward virtual impedance is added to the power system; otherwise, a reverse virtual impedance is added to the power system.

[0052] Specifically, when a short circuit fault occurs on the grid side, the voltage at the point of connection (POC) (or point of common coupling (PCC)) drops rapidly. At this time, the voltage difference between the valve side and the POC (or PCC) point will need to be borne by the converter filter inductance and line impedance, but due to the large overall voltage drop and small impedance value, it is very easy to cause a large current. When the current exceeds the converter's tolerance, it will cause damage to its hardware equipment. Therefore, it is necessary to limit the output current through control means. In order to reduce the impact on the system's voltage support network construction capability, a common practice at this stage is to suppress overcurrent through virtual impedance technology. On the basis of not introducing additional system costs and operating losses, the machine-end voltage reference value is reduced, and the current benchmark is reduced, thereby suppressing the development of overcurrent.

[0053] Taking a typical grid-type control scheme as an example, the virtual impedance link is generally applied between the system power control link (such as the droop control link, VSG control link, etc.) and the voltage and current dual closed-loop cascade control.

[0054] It should be noted that when connecting the virtual impedance to the system, many designers often deliberately design the current flowing through the virtual impedance to be reverse, that is, flowing from the grid side to the valve side. It can be understood as adding a reverse virtual impedance, which is also the traditional virtual impedance in the relevant research field. At this time, the virtual impedance is not added to the system in a similar way to line impedance or load, but becomes part of the equivalent internal impedance on the source side of the converter. Its control block diagram is as follows Figure 2 As shown, the expression is shown in formula (1).

[0055]

[0056] In this way, it is equivalent to subtracting the voltage drop caused by the virtual impedance from the original output voltage of the converter, thereby reducing the valve side voltage and further suppressing the overcurrent.

[0057] In MATLAB / Simulink, an equivalent simulation model based on a grid-connected converter is built. In order to remove the influence of unnecessary sensitive factors on the simulation results, a single-machine load system model is used, such as Figure 3 In the simulation comparison before and after the virtual impedance is connected to the system, it is found that the addition of traditional virtual impedance may cause the source end characteristics to be reshaped, that is, the voltage at the converter AC filter capacitor no longer shows a drooping characteristic relationship, but shows a "vicious upward" characteristic, that is, "same-direction decline". The lower the voltage at the machine end, the smaller the reactive power generated. Figure 4 shown. Figure 4 The added virtual impedance value increases from right to left in the figure.

[0058] The reference value of the converter machine-end voltage in the grid-type control is easier to adjust, and the reverse voltage drop caused by the virtual impedance link will also become part of the voltage reference value. In other words, once an overcurrent fault occurs in the system, under the action of the virtual impedance, the actual value and reference value of the machine-end voltage may decrease at the same time, or even fall into a vicious cycle of decreasing voltage. This runs counter to the voltage support capability that the grid-type control itself needs to have. Therefore, this "vicious upward" characteristic is very unfavorable to the stable operation of the system. Furthermore, there is a certain conflict between the roles of virtual impedance in suppressing overcurrent and achieving voltage support goals under conventional design methods.

[0059] Based on the correlation analysis, the present invention proposes a method for adding bidirectional virtual impedance, that is, when the system is operating normally, the current flowing through the virtual impedance is a positive current flowing from the valve side to the grid side, and a positive virtual impedance, i.e., a virtual external reactance, is introduced; and when an overcurrent fault occurs in the system, the current flowing through the virtual impedance is reversed, from the grid side to the valve side, and a reverse virtual impedance is introduced. In addition to being realized by changing the direction of the current flowing through it, bidirectional virtual impedance can also be realized by modifying the positive and negative values ​​of the virtual impedance. The control logic diagram of this bidirectional virtual impedance is shown in the figure. Figure 5a The change of current direction and Figure 5b The change in virtual impedance value is shown as positive or negative.

[0060] Still Figure 3 The simulation model shown in the figure is used for verification. The results show that when the system is operating normally, the use of forward virtual impedance helps to appropriately raise the voltage at the converter terminal, thereby improving its voltage support and grid-building capabilities. At this time, the reactive power-voltage waveform at the converter terminal is as follows: Figure 6 shown. Figure 6 The added virtual impedance value increases from left to right in the figure.

[0061] In one embodiment of the present invention, a bidirectional virtual impedance adding method is proposed, which mainly includes the following three steps when applied:

[0062] Step 1: Collect information such as voltage and current at key measuring points of the system (such as the converter terminal), analyze the system operation status, and determine whether the system has overcurrent risks;

[0063] Step 2: According to the result in step 1, if the system is judged to be operating normally and there is no overcurrent risk, a forward virtual impedance is added to the system to maintain the system voltage at a higher level of networking capability; if the system is judged to have an overcurrent risk, a reverse virtual impedance is added to the system to reduce the reference value and actual value of the valve side voltage and suppress the development of fault overcurrent;

[0064] Step 3: Monitor the system operating status and provide feedback to the control system.

[0065] The schematic diagram of the above main steps is as follows Figure 7 shown.

[0066] according to Figure 4 and Figure 6 The simulation results show that the proposed bidirectional virtual impedance addition method helps to improve the droop control effect and voltage support network construction capability under normal system operation, and can effectively suppress fault overcurrent when the system has overcurrent risk, effectively solving the problem that traditional virtual impedance cannot have both the effects of overcurrent suppression and voltage support.

[0067] In order to more intuitively demonstrate the impact of reverse and forward virtual impedance on the system's terminal voltage support capability, the converter terminal output voltage is simulated in three scenarios: without any virtual impedance, with traditional reverse virtual impedance, and with forward virtual impedance, to verify the network voltage support of the method proposed in this paper. The above three groups of simulation results are shown as follows: Figures 8a to 8c shown.

[0068] It is not difficult to see that after adding the forward virtual impedance mentioned in this article, the output voltage level of the converter machine end is raised (the extent of the increase is related to the parameters of the forward virtual impedance), which effectively improves its grid voltage support capability. Considering factors such as the voltage drop caused by the line impedance, it is possible to consider making the output voltage value of the converter machine end slightly higher than the rated voltage to ensure that it has a better voltage level when it is connected to the grid.

[0069] At the same time, Fig. 9 Taking the two-grid-type converter parallel load operation system model shown as an example, a working condition is set in which the difference in line distance parameters between the two converters is too large, resulting in system overcurrent. This can verify the effect of the method proposed in this patent on improving the system's ability to suppress fault overcurrent. Fig.10a and Fig.10b The current output waveforms of the converter under the working condition are shown respectively without adding virtual impedance to the system and with adding the virtual impedance mentioned in this patent. Fig.10a Overcurrent occurs. Fig.10bThis indicates that the overcurrent risk is effectively suppressed.

[0070] Taking the typical control strategy in the grid type, i.e. the droop control scheme, as an example, the virtual impedance link is generally applied between the system active-frequency, reactive-voltage droop control link and the voltage-current double closed-loop cascade control, such as Fig.11 shown.

[0071] Therefore, the present invention proposes a method for adding bidirectional virtual impedance. When the system is operating normally, the current flowing through the virtual impedance is a positive current flowing from the valve side to the grid side, and a positive virtual impedance, i.e., a virtual external reactance, is introduced; and when an overcurrent fault occurs in the system, the current flowing through the virtual impedance is reversed, from the grid side to the valve side, and a reverse virtual impedance is introduced. In addition to being realized by changing the direction of the current flowing through it, bidirectional virtual impedance can also be realized by modifying the positive and negative values ​​of the virtual impedance, which effectively improves its grid voltage support capability.

[0072] Exemplary Devices

[0073] Fig.12 FIG. 1 is a schematic diagram of a bidirectional virtual impedance adding device for a power system provided by an exemplary embodiment of the present invention. Fig.12 As shown, the apparatus 1200 includes:

[0074] The acquisition module 1210 is used to collect the operating power data of the preset key measuring points of the power system in real time, wherein the operating power data includes voltage and current;

[0075] The judgment module 1220 is used to judge whether there is an overcurrent risk in the power system in real time according to the operating power data;

[0076] The adding module 1230 is used to add a forward virtual impedance to the power system when there is no overcurrent risk in the power system, and to add a reverse virtual impedance to the power system otherwise.

[0077] Optionally, key measuring points include: converter terminals, grid connection points or public connection points, and related buses in the grid.

[0078] Optionally, the criterion for overcurrent risk is:

[0079] When the voltage of the operating power data exceeds a preset voltage threshold or the current exceeds a preset current threshold, there is an overcurrent risk; otherwise, there is no overcurrent risk.

[0080] Optionally, the forward virtual impedance is added to the power system in the form of a virtual external reactance, and the current direction on the forward virtual impedance is from the valve side to the grid side. The larger the virtual impedance, the larger the converter terminal voltage, and the larger the converter output reactive power. The smaller the virtual impedance, the smaller the converter terminal voltage, and the smaller the converter output reactive power.

[0081] Optionally, the reverse virtual impedance is added to the system in the form of an equivalent internal reactance on the source side. The current direction on the reverse virtual impedance is from the grid side to the valve side. The larger the virtual impedance, the smaller the converter machine-end voltage, and the smaller the converter output reactive power. The smaller the virtual impedance, the larger the converter machine-end voltage, and the larger the converter output reactive power.

[0082] Exemplary Electronic Devices

[0083] Fig.13 This is a structure of an electronic device provided by an exemplary embodiment of the present invention. Fig.13 As shown, the electronic device 130 includes one or more processors 131 and a memory 132 .

[0084] The processor 131 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.

[0085] The memory 132 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 131 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 133 and an output device 134, which are interconnected via a bus system and / or other forms of connection mechanisms (not shown).

[0086] In addition, the input device 133 may also include, for example, a keyboard, a mouse, etc.

[0087] The output device 134 can output various information to the outside, and can include, for example, a display, a speaker, a printer, a communication network and a remote output device connected thereto.

[0088] Of course, to simplify, Fig.13 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.

[0089] Exemplary computer program products and computer-readable storage media

[0090] 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.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] 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.

[0099] 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 bidirectional virtual impedance adding method for power system, It is characterized in that include: Real-time collection of operating power data of preset key measuring points of the power system, wherein the operating power data includes voltage and current; Determine in real time whether the power system has an overcurrent risk according to the operating power data; When there is no overcurrent risk in the power system, a forward virtual impedance is added to the power system; otherwise, a reverse virtual impedance is added to the power system.

2. The method according to claim 1, It is characterized in that The key measuring points include: converter machine end, grid connection point or public connection point, and related busbars in the grid.

3. The method according to claim 1, It is characterized in that The criterion for the overcurrent risk is: When the voltage of the operating power data exceeds a preset voltage threshold or the current exceeds a preset current threshold, there is an overcurrent risk; otherwise, there is no overcurrent risk.

4. The method according to claim 1, It is characterized in that The forward virtual impedance is added to the power system in the form of a virtual external reactance. The current direction on the forward virtual impedance is from the valve side to the grid side. The larger the virtual impedance, the larger the converter terminal voltage, and the larger the converter output reactive power. The smaller the virtual impedance, the smaller the converter terminal voltage, and the smaller the converter output reactive power.

5. The method according to claim 1, It is characterized in that The reverse virtual impedance is added to the system in the form of an equivalent internal impedance on the source side. The current direction on the reverse virtual impedance is from the grid side to the valve side. The larger the virtual impedance, the smaller the converter machine-end voltage, and the smaller the converter output reactive power. The smaller the virtual impedance, the larger the converter machine-end voltage, and the larger the converter output reactive power.

6. A bidirectional virtual impedance adding device for a power system, It is characterized in that include: A collection module, used for collecting the running power data of preset key measuring points of the power system in real time, wherein the running power data includes voltage and current; A judgment module, used for judging in real time whether the power system has an overcurrent risk according to the operating power data; The adding module is used to add a forward virtual impedance to the power system when there is no overcurrent risk in the power system, and to add a reverse virtual impedance to the power system otherwise.

7. The device according to claim 6, It is characterized in that The key measuring points include: converter machine end, grid connection point or public connection point, and related busbars in the grid.

8. The device according to claim 6, It is characterized in that The criterion for the overcurrent risk is: When the voltage of the operating power data exceeds a preset voltage threshold or the current exceeds a preset current threshold, there is an overcurrent risk; otherwise, there is no overcurrent risk.

9. The device according to claim 6, It is characterized in that The forward virtual impedance is added to the power system in the form of a virtual external reactance. The current direction on the forward virtual impedance is from the valve side to the grid side. The larger the virtual impedance, the larger the converter terminal voltage, and the larger the converter output reactive power. The smaller the virtual impedance, the smaller the converter terminal voltage, and the smaller the converter output reactive power.

10. The device according to claim 6, It is characterized in that The reverse virtual impedance is added to the system in the form of an equivalent internal impedance on the source side. The current direction on the reverse virtual impedance is from the grid side to the valve side. The larger the virtual impedance, the smaller the converter machine-end voltage, and the smaller the converter output reactive power. The smaller the virtual impedance, the larger the converter machine-end voltage, and the larger the converter output reactive power.

11. A computer-readable storage medium, It is 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, It is 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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