Method, system, equipment and medium for dynamically adjusting network following-network construction rated capacity ratio and operation output

Abstract

The invention discloses a method, a system, equipment and a medium for dynamically adjusting a network following-network constructing rated capacity ratio and operation output. The method comprises the following steps of: determining a dominant modal damping ratio of a new energy station by utilizing a modal analysis method; when the dominant mode damping ratio is larger than the dominant mode damping ratio lower bound required by small disturbance stability or the stability improvement effect is lower than the minimum stability margin improvement limit, the rated capacity ratio of the new energy station is determined; based on the rated capacity ratio, the number of the converters under the network following control condition and the network construction control condition is determined, and when the new energy station is small in power generation, the converters under the network following control condition bear all active power output in the station, and the converters under the network following control condition do not output power; and when the new energy station is in a large power generation state, all the converters in the network following control condition are in a rated output state, and the remaining active output is borne by the converters in the network construction control condition. According to the invention, full-scene stability and stability margin optimization can be realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of power system control, and particularly relates to a grid-following-grid-forming rated capacity ratio and operation output dynamic adjustment method, system, device and medium. BACKGROUND

[0002] New energy stations widely adopt grid-following control, which relies on a phase-locked loop to achieve grid synchronization, but is prone to subsynchronous oscillation caused by the interaction of grid impedance and the phase-locked loop under a weak grid, and cannot actively support voltage frequency stability. Therefore, grid-forming control emerges as the times require, which can provide inertia support and oscillation suppression capability by simulating the external characteristics of synchronous machines to build an autonomous voltage source, overcoming the subsynchronous oscillation problem caused by the phase-locked loop under a weak grid in traditional grid-following control. However, the overcurrent capability of grid-forming converters is limited, and there is a risk of low-frequency oscillation in a strong grid. Therefore, grid-following converters are suitable for high short-circuit ratio scenarios, and grid-forming converters are more suitable for low short-circuit ratio scenarios.

[0003] In order to solve the above problems, hybrid new energy stations with grid-following strong grid adaptability and grid-forming weak grid adaptability have gradually become the development trend of high-proportion new energy grid connection. Research shows that increasing a small number of grid-forming control units in new energy stations can support the instability mode of units under traditional grid-following control and improve their stable operation capability. The ratio of grid-forming converters in new energy stations directly affects system stability: increasing the ratio of grid-forming converters under a weak grid can enhance voltage support and suppress subsynchronous oscillation, but excessive configuration may cause low-frequency oscillation in a strong grid, so it is necessary to determine the rated capacity ratio according to the strength of the grid. At present, existing technologies mostly use short-circuit ratio or short-circuit ratio of multiple new energy stations as the criterion for measuring system stability and increasing the ratio of grid-forming converters, and calculate the ratio of grid-forming converters when the system is critically stable. The ratio calculated by the system critical stability lacks stability margin, and there is a risk of instability under long-term operation. SUMMARY

[0004] The purpose of the present application is to provide a grid-following-grid-forming rated capacity ratio and operation output dynamic adjustment method, system, device and medium to solve one or more problems in the prior art.

[0005] Technical solution: A grid-following-grid-forming rated capacity ratio method of the present application comprises:

[0006] Obtain the small signal model of the new energy station under the initial state and perform modal analysis to obtain the dominant modal damping ratio ζ0 of the new energy station; the initial state is that all the active power commands P ref of all the converters in the new energy station are at rated value;

[0007] If ζ0 does not meet the preset conditions, the single converter is continuously switched from grid-following control conditions to grid-connecting control conditions. The small-signal model of the new energy power station under the current state is obtained and modal analysis is performed on it to obtain the dominant mode damping ratio ζ of the new energy power station when i converters are switched from grid-following control conditions to grid-connecting control conditions. i , until ζ i Meets the preset conditions;

[0008] In the dominant mode damping ratio ζ i When the preset conditions are met, the number N of converters under grid control conditions in the new energy power station is used as the basis. GFM Determine the rated capacity ratio η based on the total number of converters N;

[0009] When the converter is controlled under grid-following control conditions, the active power command is the same as when the converter is controlled under grid-connecting control conditions.

[0010] Furthermore, in ζ0>ζ low When, it means that ζ0 satisfies the preset condition, where ζ low This represents the lower bound of the dominant mode damping ratio that satisfies the small disturbance stability requirement.

[0011] Furthermore, in ζ i >ζ low Or ζ i -ζ i-1 When ≤ε, it means ζ i The preset conditions are met, where ζ low ε represents the lower bound of the dominant mode damping ratio that satisfies the small disturbance stability requirement, and ε represents the minimum stability margin improvement limit.

[0012] Furthermore, the rated capacity ratio η is, at the dominant modal damping ratio ζ i When the preset conditions are met, the number N of converters in the new energy power station under grid control conditions is... GFM The ratio of the total number of converters N to the total number of converters N.

[0013] Furthermore, the total number N of converters is based on the rated capacity P of the new energy power station. resN and the rated capacity P of the individual converter conN It is certain that P is satisfied. resN =N·P conN .

[0014] Furthermore, the active power command P of the converter ref The rated value and the rated capacity P of the individual converter conN They are the same size.

[0015] Based on the same inventive concept, the present invention provides a grid-to-grid rated capacity matching system, comprising:

[0016] a modal analysis module, configured to acquire a small signal model of the new energy station in an initial state and perform modal analysis on the small signal model to obtain a dominant modal damping ratio ζ0 of the new energy station, and when the converter control module continuously switches a single converter from the grid-following control condition to the grid-forming control condition, acquire a small signal model of the new energy station in a current state and perform modal analysis on the small signal model to obtain a dominant modal damping ratio ζi of the new energy station when the i-th converter is switched from the grid-following control condition to the grid-forming control condition i ; the initial state is that all the converters in the new energy station are in the grid-following control condition, and the active power instruction P ref of all the converters is the rated value;

[0017] a judgment module, configured to judge whether the ζ0 meets a preset condition, and judge whether the ζi meets a preset condition; i

[0018] a converter control module, configured to perform converter control mode switching and active power instruction adjustment; if the ζ0 does not meet the preset condition, the single converter is continuously switched from the grid-following control condition to the grid-forming control condition until the ζi meets the preset condition; the control mode of the converter when the control mode of the converter is the grid-following control condition is consistent with the control mode of the converter when the control mode of the converter is the grid-forming control condition; i

[0019] a rated capacity ratio calculation module, configured to, when the dominant modal damping ratio ζ i meets the preset condition, determine a rated capacity ratio η according to the number N GFM of the converters in the grid-forming control condition and the total number N of the converters in the new energy station.

[0020] Further, when the ζ0 > ζ low , it is indicated that the ζ0 meets the preset condition, where ζ low represents a lower bound of the dominant modal damping ratio meeting a small disturbance stability requirement.

[0021] Further, when the ζ i > ζ low or the ζ i - ζ i-1 ≤ ε, it is indicated that the ζ i meets the preset condition, where ζ low represents the lower bound of the dominant modal damping ratio meeting the small disturbance stability requirement, and ε represents a minimum stability margin improvement limit.

[0022] Further, the rated capacity ratio η is, when the dominant modal damping ratio ζ i meets the preset condition, the number N GFM ​​The ratio of the total number of converters N to the total number of converters N.

[0023] Furthermore, the total number N of converters is based on the rated capacity P of the new energy power station. resN and the rated capacity P of the individual converter conN It is certain that P is satisfied. resN =N·P conN .

[0024] Furthermore, the active power command P of the converter ref The rated value and the rated capacity P of the individual converter conN They are the same size.

[0025] Based on the same inventive concept, the present invention provides a grid-to-grid rated capacity matching device, comprising a processor and a memory, wherein the memory stores computer instructions, and the processor is used to execute the computer instructions stored in the memory. When the computer instructions are executed by the processor, the electronic device implements the steps of the above-described grid-to-grid rated capacity matching method.

[0026] Based on the same inventive concept, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-described method for matching the rated capacity of the network-network structure.

[0027] The present invention provides a method for dynamic adjustment of power output during grid-connection operation, comprising:

[0028] The number of converters in a new energy power station under grid connection control is N. GFM The number of converters under grid-connected control conditions is N. GFL ;where N GFM Based on the above-mentioned method for matching the rated capacity of the grid-structure network, N is determined. GFM and N GFL The sum of these is the total number of converters, N;

[0029] Obtain the real-time power generation P of the new energy power station res ;

[0030] When the real-time power generation P of the new energy power station res Less than or equal to the total rated capacity P of all converters under grid-connected control conditions GFLN At that time, the active power command of all converters under grid control conditions is adjusted to 0, and the real-time power generation P of the new energy power station is... res The distribution is evenly distributed among the converters under grid control conditions.

[0031] When the real-time power generation P of the new energy power station res Greater than the total rated capacity P of all converters under grid-connected control conditionsGFLN When the grid strength changes, the rated capacity ratio and the operation output are re-determined. GFM GFM res GFLN .

[0032] Further, the method of the grid-forming converter outputting one by one is that when one grid-forming converter under the grid-forming control condition is full-load, the next grid-forming converter under the grid-forming control condition is enabled.

[0033] Further, whether the grid strength changes is determined according to the following formula:

[0034]

[0035] wherein, SCR represents the grid strength; P resN is the rated capacity of the new energy station; Z g is the grid impedance; E N is the rated voltage of the point of common coupling;

[0036] When the grid strength changes, the rated capacity ratio and the operation output are re-determined.

[0037] Based on the same inventive concept, the follow-grid-grid-forming operation output dynamic adjustment system of the present application comprises the follow-grid-grid-forming rated capacity ratio system described above;

[0038] The judging module is further configured to acquire the real-time power P res of the new energy station, and determine the size relationship between the real-time power P res of the new energy station and the total rated capacity P GFLN of all the converters under the follow-grid control condition.

[0039] The converter control module is further configured to, when the real-time power P res of the new energy station is less than or equal to the total rated capacity P GFLN of all the converters under the follow-grid control condition, adjust the active power instruction of all the converters under the grid-forming control condition to 0, and the real-time power P res of the new energy station is evenly distributed by all the converters under the follow-grid control condition; when the real-time power P res of the new energy station is greater than the total rated capacity P GFLN of all the converters under the follow-grid control condition, set the active power instruction of each converter under the follow-grid control condition to the rated value, and the remaining power P GFM ​​​The power distribution is borne by the converter under the grid-constructing control condition; P GFM = P res -P GFLN .

[0040] Further, the grid-constructing converter step-by-step power output method is that when a converter under the grid-constructing control condition is full-load, the next converter under the grid-constructing control condition is enabled.

[0041] Further, the grid-constructing converter step-by-step power output method is that when a converter under the grid-constructing control condition is full-load, the next converter under the grid-constructing control condition is enabled.

[0042] The grid strength identification module is used for collecting grid impedance data and calculating the grid strength through The grid strength is calculated, wherein P resN is the rated capacity of the new energy station; Z g is the grid impedance; E N is the rated voltage of the point of common coupling;

[0043] The judgment module is further used for judging whether the grid strength changes according to the grid strength SCR value; when the grid strength changes, the rated capacity ratio and the operation power are re-determined.

[0044] Based on the same inventive concept, the electronic device of the grid-following-grid-constructing operation power dynamic adjustment method comprises a processor and a memory, the memory stores computer instructions, and the processor is used for executing the computer instructions stored in the memory, when the computer instructions are executed by the processor, the electronic device realizes the steps of the grid-following-grid-constructing operation power dynamic adjustment method.

[0045] Based on the same inventive concept, the electronic device of the grid-following-grid-constructing operation power dynamic adjustment method comprises a processor and a memory, the memory stores computer instructions, and the processor is used for executing the computer instructions stored in the memory, when the computer instructions are executed by the processor, the electronic device realizes the steps of the grid-following-grid-constructing operation power dynamic adjustment method.

[0046] Advantages: compared with the prior art, the present application has the following obvious advantages:

[0047] The small signal model of the new energy station is subjected to modal analysis to obtain the dominant modal damping ratio ζ i as a stability margin index; when ζ i is higher than a preset lower limit ζ low or ζ i - ζ i-1 > ε, the converter is switched from the grid-following control condition to the grid-constructing control condition and ζ i is re-calculated until ζ i - ζ low or ζ i - ζ i-1≤ε, to determine the rated capacity ratio of grid-forming converter. The present application has the advantages of simplicity, intuition, safety, etc. By taking the dominant mode damping ratio of the small signal model of the new energy station as an intuitive index of stability margin, engineers can make more quantitative and comparable evaluation of the dynamic characteristics of the new energy station. Under the premise of leaving a certain margin, calculating the grid-forming converter ratio is equivalent to reserving a safety buffer between the ideal stability boundary and the actual operating condition.

[0048] The operation output dynamic adjustment method provided by the present application is based on the real-time power P res and the total rated capacity P GFLN of the grid-following converter. res When P GFLN ≤ P res , the grid-following converter is idle and the grid-forming converter shares the power averagely; when P GFLN > P GFM , the grid-following converter is fully loaded first, and then the grid-forming converter is started in order. This method makes full use of the advantages of high-precision tracking and harmonic suppression of the grid-following converter, and reserves the capacity of the grid-forming converter as virtual inertia, which can quickly respond to faults, voltage dips or frequency mutations in milliseconds, and realize voltage and frequency stability support. In summary, for the system stability problem caused by the grid-forming converter ratio in the new energy station, the present application determines the rated capacity ratio of grid-following-grid-forming based on off-line grid parameters, and adjusts the active power instruction of the converter online in combination with real-time working conditions, which can realize full-scenario stability and optimal stability margin. BRIEF DESCRIPTION OF DRAWINGS

[0049] Figure 1 is a main circuit schematic diagram of a new energy station containing a grid-following-grid-forming converter in an embodiment of the present application;

[0050] Figure 2 is a flow chart of a grid-following-grid-forming rated capacity ratio and operation output dynamic adjustment method provided by an embodiment of the present application;

[0051] Figure 3 is a dominant mode trajectory of a new energy station when N GFM increases from 0 to 5. DETAILED DESCRIPTION

[0052] The present application will be described in detail below with reference to the accompanying drawings and specific embodiments. Those skilled in the art will understand that the purposes and advantages that can be achieved by the present application are not limited to the specific beneficial effects described above, and the above and other purposes that can be achieved by the present application will be more clearly understood according to the following detailed description.

[0053] Those skilled in the art will understand that the exemplary components, systems, and methods described in conjunction with the embodiments disclosed herein can be implemented in hardware, software, or a combination of both. Whether implemented in hardware or software depends on the specific application, design, and conditions of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0054] In this invention, the term "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0055] Example 1

[0056] Please see Figure 1 , Figure 1 This is a schematic diagram of the main circuit of a new energy power station including a grid-connected converter, where P resN For the rated capacity of new energy power stations, P GFL To match the actual output of the grid converter, P GFM For the actual output of the grid converter, For the equivalent grid voltage phasor, For the voltage phasor at the point of common coupling, To connect to the grid converter output current phasor, To represent the dq-axis component of the grid converter output current in the phase-locked loop coordinate system, θ PLL To match the phase angle of the phase-locked loop output of the grid converter, Let V be the output voltage phasor of the grid-connected converter, V be the output voltage amplitude of the grid-connected converter, and θ be the output voltage amplitude of the grid-connected converter. APC For the active power loop output phase angle of the grid converter, Z g This is the grid impedance. This hybrid renewable energy power station combines the adaptability to both strong and weak grids.

[0057] According to the rated capacity P of the new energy power station resN Determine the required unit capacity P of the converter. conN And the total number of converters N, P resN P conN N and N satisfy the following relationship:

[0058] P resN =N·P conN

[0059] In specific implementation, when the rated capacity planning of the new energy station is determined, the parameters such as the single capacity and the number of the converter can be obtained from the converter nameplate, the equipment manufacturer, the power design institute and the like.

[0060] As shown in Figure 2 , embodiment 1 provides a follow-network-construct-network rated capacity matching method, which can include the following operations:

[0061] S1, obtaining a small signal model of the new energy station in an initial state and performing modal analysis on the small signal model to obtain a dominant modal damping ratio ζ0 of the new energy station.

[0062] The initial state is that all the converters in the new energy station are in a follow-network control condition, and the active power instruction P ref of all the converters is a rated value, that is, the number N GFL of the converters in the follow-network control condition is N, the number N GFM of the converters in the construct-network control condition is 0; the rated value in this embodiment is configured as 1 p.u., that is, the rated value of the active power instruction P ref of the converter is equal to the single rated capacity P conN of the converter.

[0063] The establishment of the small signal model of the new energy station first obtains a steady state working point of all the converters in the new energy station under the follow-network control condition in the initial state, and the steady state working point is obtained by the main circuit equation or the power flow calculation, and then the small signal model of the new energy station is established based on the steady state working point. This part is prior art, and the small signal model of the new energy station in step S3 is established by the same method.

[0064] S2, if ζ0 meets a preset condition, it is considered that the follow-network operation of the new energy station can guarantee the stability of the system, and the construct-network control does not need to be introduced; if ζ0 does not meet the preset condition, step S3 is entered;

[0065] When ζ0 meets formula (1), it indicates that ζ0 meets the preset condition:

[0066] ζ0> ζ low (1)

[0067] Wherein, ζ low represents the lower bound of the dominant modal damping ratio that meets the corresponding small disturbance stability requirement in the standard (for example, the frequency oscillation attenuation required in GB / T40581-2021 “Calculation Specification for Safety and Stability of Power System”, the minimum damping ratio should be 0.02-0.03).

[0068] S3, switching 1 converter from the follow-network control condition to the construct-network control condition without changing the active power instruction, that is:

[0069] NGFM =N GFM +1

[0070] N GFL =N GFL -1

[0071] Obtain the small-signal model of the renewable energy power station under the current state and perform modal analysis on it to obtain the dominant mode damping ratio ζ of the renewable energy power station when the i converters are switched from grid-following control conditions to grid-connecting control conditions. i , until ζ i The preset conditions are met.

[0072] ζ i With ζ low Compare and determine the damping ratio ζ of the dominant mode of the system at this time. i Whether the small disturbance stability requirement is met is shown in equation (2); such as ζ i If the stability requirement is not met, proceed to step S4; for example, ζ i If the stability requirement is met, proceed to step S5;

[0073] ζ i >ζ low (2)

[0074] S4. The dominant mode damping ratio ζ of the new energy power station during this modal analysis. i Compared with the dominant mode damping ratio ζ of the new energy power station in the previous modal analysis i-1 Perform a difference operation to determine whether the stability improvement effect caused by switching the converter's control mode from grid-following control conditions to grid-connected control conditions has reached its limit, i.e.:

[0075] ζ i -ζ i-1 ≤ε (3)

[0076] Where ε represents the minimum stability margin improvement limit.

[0077] When the dominant mode damping ratio ζ i If equation (3) is satisfied, proceed to step S5; otherwise, if the stability improvement effect has not reached the limit, return to step S3, continue to switch the control mode of one converter from grid-following control condition to grid-connecting control condition, and repeat the above process until the dominant mode damping ratio of the new energy power station reaches the stability requirement or the stability improvement effect is less than or equal to the minimum stability margin improvement limit.

[0078] Therefore, in ζ i >ζ low Or ζ i -ζ i-1 When ≤ε, it means ζ i The preset conditions are met.

[0079] S5, the rated capacity ratio η is:

[0080]

[0081] Where, N GFM N represents the number of grid converters. GFL The number of grid converters.

[0082] This invention uses the dominant mode damping ratio ζ of new energy power stations i The magnitude of ζ measures the stability of the system. As the capacity of converters under grid-connected control conditions increases, the dominant mode damping ratio ζ of renewable energy power plants... i As the value changes from negative to positive and continues to increase, the system changes from unstable to stable, and the stability margin continues to increase. When equation (2) or equation (3) is satisfied, the rated capacity ratio η of the grid-connected converters in the new energy power station is considered to be optimal.

[0083] Figure 3 The figure shows N GFM The dominant mode trajectory of the renewable energy power station as the value increases from 0 to 5. The imaginary part of the dominant mode of the renewable energy power station remains basically unchanged, and the corresponding oscillation frequency can be considered unchanged. The real part of the dominant mode moves from the right half-plane to the left half-plane, indicating that the renewable energy power station has recovered from an unstable state to stable operation, and the stability is continuously improving, corresponding to a continuous increase in the damping ratio of the dominant mode.

[0084] Example 2

[0085] Example 2 provides a grid-to-grid rated capacity matching system, comprising:

[0086] The modal analysis module is used to acquire the small-signal model of the renewable energy power station in the initial state and perform modal analysis on it to obtain the dominant modal damping ratio ζ0 of the renewable energy power station; and, as the converter control module continuously switches a single converter from grid-fed control conditions to grid-connected control conditions, it acquires the small-signal model of the renewable energy power station in the current state and performs modal analysis on it to obtain the dominant modal damping ratio ζ0 of the renewable energy power station when i converters are switched from grid-fed control conditions to grid-connected control conditions. i The initial state is when all converters in the new energy power station are under grid-connected control conditions, and the active power command P of all converters is... ref All values ​​are rated values. In this embodiment, the rated value is configured as 1p.u., which is the active power command P of the converter. ref The rated value and the rated capacity P of the individual converter conN They are the same size.

[0087] The judgment module is used to determine whether ζ0 meets the preset condition, and to determine ζ iwhether the preset condition is met;

[0088] when ζ0> ζ low , it indicates that ζ0meets the preset condition, where ζ low represents the lower bound of the dominant mode damping ratio that meets the corresponding small disturbance stability requirement in the standard (for example, the frequency oscillation attenuation requirement in GB / T 40581-2021 “Power System Safety Stability Calculation Specification”, and the minimum damping ratio should be 0.02-0.03).

[0089] when ζ i > ζ low or ζ i - ζ i-1 ≤ ε, it indicates that ζ i meets the preset condition, where ε represents the minimum stability margin improvement limit.

[0090] a converter control module, configured to perform converter control mode switching and active power instruction adjustment; if ζ0does not meet the preset condition, the single converter is continuously switched from the grid-following control condition to the grid-forming control condition until ζ i meets the preset condition; the active power instruction of the converter when the control mode is the grid-following control condition is consistent with the active power instruction of the converter when the control mode is the grid-forming control condition;

[0091] a rated capacity ratio calculation module, configured to, when the dominant mode damping ratio ζ i meets the preset condition, determine the rated capacity ratio η according to the number N GFM of the converters in the grid-forming control condition in the new energy station and the total number N of the converters.

[0092] the rated capacity ratio η is:

[0093]

[0094] where N GFM is the number of grid-forming converters, and N GFL is the number of grid-following converters.

[0095] Embodiment 3

[0096] Embodiment 3 provides a grid-following-grid-forming rated capacity ratio device, which comprises a processor and a memory, the memory stores computer instructions, and the processor is configured to execute the computer instructions stored in the memory. When the computer instructions are executed by the processor, the electronic device implements the steps of the grid-following-grid-forming rated capacity ratio method in embodiment 1 and achieves consistent technical effects.

[0097] The memory can include a computer system readable media in the form of volatile memory, such as random access memory (RAM) and / or cache memory. The device can further include other removable / non-removable, volatile / non-volatile computer system storage media. By way of example only, storage media can be used for reading and writing non-removable, non-volatile media such as magnetic tapes, magnetic disks (e.g., hard disk drives), solid state drives, etc. It will be appreciated that the memory, storage media, and other storage are examples of computer system readable storage that can be used to store data and / or instructions that can direct the functioning of the processor.

[0098] The processor performs various function applications and data processing by running programs stored in the memory, such as implementing the method provided by embodiment 1 of the present application.

[0099] Embodiment 4

[0100] Embodiment 4 provides a computer readable storage medium, which stores a computer program. The program is executed by a processor to implement the steps of the follow-me-network-capacity-configuration method described in embodiment 1, and achieve the consistent technical effects.

[0101] The computer storage medium of the embodiments of the present application can adopt any combination of one or more computer readable media. The computer readable medium can be a computer readable signal medium or a computer readable storage medium. The computer readable storage medium may, for example, but is not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device or apparatus, or any combination of the above. More specific examples (non-exhaustive list) of the computer readable storage medium include: an electrical connection having one or more wires, a portable computer diskette, 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. In this document, the computer readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, device or apparatus.

[0102] Computer-readable signal media may include data signals propagated in baseband or as part of a carrier wave, carrying computer-readable program code. Such propagated data signals may take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. Computer-readable signal media may also be any computer-readable medium other than computer-readable storage media, capable of sending, propagating, or transmitting programs for use by or in connection with an instruction execution system, apparatus, or device.

[0103] Program code contained on a computer-readable medium may be transmitted using any suitable medium, including but not limited to wireless, wire, optical fiber, RF, etc., or any suitable combination thereof.

[0104] Computer program code for performing the operations of this invention can be written in one or more programming languages ​​or a combination thereof. Programming languages ​​include object-oriented programming languages ​​such as Java, Smalltalk, and C++, as well as conventional procedural programming languages ​​such as C or similar languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network, including a local area network (LAN) or a wide area network (WAN), or it can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0105] Example 5

[0106] After determining the number of the two types of converters based on the above grid-to-grid rated capacity matching method, since the output of new energy power plants fluctuates greatly, each converter will not always be in rated operating condition. Therefore, it is also necessary to adjust the real-time output of the converters.

[0107] like Figure 2 As shown, Embodiment 5 provides a method for dynamically adjusting the output of the grid-connected system, which may include the following operations:

[0108] (1) The number of converters in the new energy power station under grid connection control conditions is N. GFM The number of converters under grid-connected control conditions is N. GFL ;where N GFM According to the grid-network rated capacity ratio method described in Example 1, N is determined as follows: GFM and N GFL The sum of these is the total number of converters, N;

[0109] (2) Obtain the real-time power generation P of the new energy power station res Real-time power generation P of new energy power plants res Based on the intensity of solar radiation or wind speed, this is an existing technology. The actual power generation of photovoltaic new energy power plants is directly related to the effective solar radiation intensity incident on their surface, with an approximately linear proportional relationship. The actual power generation of wind power new energy power plants is closely related to the wind speed at the hub height, following a specific power curve.

[0110] When the real-time power generation P of the new energy power station res Less than or equal to the total rated capacity P of all converters under grid-connected control conditions GFLN When (i.e., during small-scale power generation), the active power command of all converters under grid control conditions is adjusted to 0, and the real-time power generation P of the new energy power station is... res The distribution is evenly distributed among the converters under grid control conditions, i.e.:

[0111] P GFMref =0

[0112]

[0113] Total capacity P of grid converter GFLN It can be represented as:

[0114] P GFLN =N GFL ·P conN

[0115] When the real-time power generation P of the new energy power station res Greater than the total rated capacity P of all converters under grid-connected control conditions GFLN (i.e., during peak power generation) the active power command of each converter under grid control conditions is set to the rated value, and the remaining generating power P is distributed by using the method of one converter outputting power one by one in the grid. GFM The load is allocated to converters operating under network control conditions; P GFM =P res -P GFLN The method for sequentially activating grid-connected converters is as follows: once a converter under grid-connected control conditions has reached full capacity, the next converter under grid-connected control conditions will be activated.

[0116] (3) Determine whether the power grid strength has changed according to the following formula:

[0117]

[0118] Where SCR represents grid strength; P resN Rated capacity for new energy power stations; Z g E represents the power grid impedance. NThe rated voltage of the point of common coupling.

[0119] Steps (1) to (2) are repeated to re-determine the rated capacity ratio and the operating output when the grid strength changes.

[0120] Embodiment 6

[0121] Embodiment 6 provides a grid-following-grid-forming operating output dynamic adjustment system, which comprises the grid-following-grid-forming rated capacity ratio system and the grid strength identification module described in Embodiment 2.

[0122] The grid strength identification module is configured to collect grid impedance data and calculate the grid strength by wherein P resN is the rated capacity of the new energy station; Z g is the grid impedance; and E N is the rated voltage of the point of common coupling.

[0123] The judging module is further configured to acquire the real-time power P res of the new energy station, determine the size relationship between the real-time power P res of the new energy station and the total rated capacity P GFLN of all the grid-following converters, and determine whether the grid strength changes according to the grid strength SCR value, and re-determine the rated capacity ratio and the operating output when the grid strength changes.

[0124] The converter control module is further configured to, when the real-time power P res of the new energy station is less than or equal to the total rated capacity P GFLN of all the grid-following converters, adjust the active power command of all the grid-forming converters to 0, and average the real-time power P res of the new energy station among all the grid-following converters; and when the real-time power P res of the new energy station is greater than the total rated capacity P GFLN of all the grid-following converters, set the active power command of each grid-following converter to the rated value, and distribute the remaining power P GFM to the grid-forming converters to be borne by the grid-forming converters in a grid-forming converter-by-grid-forming converter output manner; P GFM = P res -P GFLN . The grid-forming converter-by-grid-forming converter output manner is to start using the next grid-forming converter after one grid-forming converter is fully loaded.

[0125] Embodiment 7

[0126] Embodiment 7 provides a follow-network-construct-network operation output dynamic adjustment device, comprising a processor and a memory, the memory has computer instructions stored therein, the processor is used for executing the computer instructions stored in the memory, when the computer instructions are executed by the processor, the electronic device realizes the steps of the follow-network-construct-network operation output dynamic adjustment method in embodiment 5 and can achieve consistent technical effects.

[0127] Embodiment 8

[0128] Embodiment 8 provides a computer readable storage medium, which has a computer program stored thereon, the program is executed by a processor, realizes the steps of the follow-network-construct-network operation output dynamic adjustment method in embodiment 5 and can achieve consistent technical effects.

[0129] The above specific embodiments further illustrate the purpose, technical scheme and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method of matching the capacity rating of a network to the capacity of a network, characterized by, The control mode of the converter is consistent with the active power instruction when the control mode of the converter is in the grid-connected control condition. Obtaining a small signal model of the new energy station in an initial state and performing modal analysis on the small signal model to obtain a dominant modal damping ratio ζ0 of the new energy station; the initial state is that active power instructions P of all the variable converters in the new energy station are all rated values under grid-following control ref ​ If ζ0 does not satisfy the preset condition, the single converter is switched from the grid-following control condition to the grid-forming control condition, a small signal model of the new energy station in the current state is obtained and modal analysis is performed thereon to obtain the dominant modal damping ratio ζ of the new energy station when the i converter is switched from the grid-following control condition to the grid-forming control condition i , until ζ i satisfies the preset condition; In the dominant modal damping ratio ζ i When the preset condition is met, according to the number N of the converter in the grid-constructing control condition in the new energy station GFM And the total number N of the converter, the rated capacity ratio η is determined; 7. A grid-connected and grid-forming rated capacity matching system, characterized in that it comprises:

2. The follow-the-sun-capacity-rating method of claim 1, wherein, when ζ0> ζ low indicates that ζ0satisfies the preset condition, where ζ low represents the lower bound of the dominant modal damping ratio satisfying the small-disturbance stability requirement.

3. The follow-the-sun-capacity-rating method of claim 1, wherein, In ζ i >ζ low Or ζ i -ζ i-1 ≤ε, indicates ζ i Satisfies the preset condition, wherein ζ low Indicates the lower bound of the dominant modal damping ratio that meets the small disturbance stability requirement, and ε indicates the minimum stable margin improvement limit.

4. The follow-the-sun-capacity-rating method of claim 1, wherein, The rated capacity ratio η is, in the dominant modal damping ratio ζ i When the preset condition is met, the number N of the converter in the new energy station under the network construction control condition GFM The ratio of the number N of the converter to the total number N of the converter.

5. The over-the-top-capacity-ratio method according to claim 1, wherein The total number N of the converter is determined according to the rated capacity P of the new energy station resN and the single rated capacity P of the converter conN The determined P resN = N·P conN satisfies.

6. The over-the-top-capacity-ratio method of claim 1, wherein, The active power command P of the converter ref The rated value of the active power command P is equal in size to the individual rated capacity P of the converter conN The rated value of the active power command P is equal in size to the individual rated capacity P of the converter The modal analysis module is configured to obtain a small signal model of the new energy station in an initial state and perform modal analysis on the small signal model to obtain a dominant modal damping ratio ζ0 of the new energy station.

13. A grid-connected and grid-forming rated capacity matching device, characterized in that it comprises a processor and a memory, and the memory stores computer instructions, and the processor is configured to execute the computer instructions stored in the memory, and when the computer instructions are executed by the processor, the electronic device implements the steps of the grid-connected and grid-forming rated capacity matching method of any one of claims 1 to 6. And, when the converter control module continuously switches a single converter from the grid-following control condition to the grid-forming control condition, a small signal model of the new energy station in the current state is obtained and modal analysis is performed thereon to obtain a dominant modal damping ratio ζ of the new energy station when the i-th converter is switched from the grid-following control condition to the grid-forming control condition i ; the initial state is that all the converters in the new energy station are in the grid-following control condition, and the active power instruction P ref of all the converters is the rated value; a judging module, configured to judge whether ζ0 satisfies a preset condition and judge whether ζ i satisfies a preset condition. The converter control module is used for switching the converter control mode and adjusting the active power instruction; if ζ0 does not meet the preset condition, the single converter is switched from the grid-following control condition to the grid-forming control condition until ζ i meets the preset condition; the active power instruction is consistent when the control mode of the converter is the grid-following control condition and when the control mode of the converter is the grid-forming control condition; The rated capacity ratio calculation module is configured to calculate a rated capacity ratio η according to the number N of the variable converters in the grid-forming control condition in the new energy station i When the preset condition is met, the rated capacity ratio η is determined according to the number N of the variable converters in the grid-forming control condition in the new energy station GFM and the total number N of the variable converters.

8. The web-ratio capacity provisioning system of claim 7, wherein, ζ0 > ζ low , indicates that ζ0 satisfies the preset condition, wherein ζ low represents a lower bound of a dominant modal damping ratio satisfying a small-disturbance stability requirement.

9. The web-architect capacity rating system of claim 7, wherein, In ζ i > ζ low Or ζ i - ζ i-1 ≤ ε, indicates ζ i Satisfies the preset condition, wherein ζ low Indicates the lower bound of the dominant modal damping ratio that meets the small disturbance stability requirement, and ε indicates the minimum stability margin improvement limit.

10. The over-the-top-capacity-ratio system of claim 7, wherein, The rated capacity ratio η is, in the dominant modal damping ratio ζ i The number N of the converters in the new energy station under the grid construction control condition when the preset condition is met GFM The ratio of the number N of the converters to the total number of the converters.

11. The web-ratio capacity provisioning system of claim 7, wherein, The total number N of the converter is determined according to the rated capacity P of the new energy station resN and the single rated capacity P of the converter conN is determined, satisfying P resN =N·P conN .

12. The web-ratio capacity provisioning system of claim 7, wherein, The active power command P of the converter ref The rated value of the active power command P is equal in size to the individual rated capacity P of the converter conN The rated value of the active power command P is equal in size to the individual rated capacity P of the converter The computer readable storage medium stores a computer program, and when the computer program is executed by the processor, the steps of the grid-connected and grid-forming rated capacity matching method of any one of claims 1 to 6 are implemented.

14. A computer-readable storage medium, characterized in that, The method for gradually outputting power of the grid-forming converter comprises the following steps:

15. A method for dynamically adjusting output power in a follow-the-sun-build-the-network operation, characterized in that, The grid strength is determined according to the following formula: The number of the converters in the new energy station under the grid-constructing control condition is N GFM , the number of the converters under the grid-following control condition is N GFL ; wherein N GFM The sum of N GFM and N GFL is the total number of the converters N. Obtaining real-time power P generated by a new energy station res ; When the real-time power P res of the new energy station is less than or equal to the total rated capacity P GFLN of all the converters under grid-following control condition, the active power instruction of all the converters under grid-forming control condition is adjusted to 0, and the real-time power P res of the new energy station is evenly distributed by each converter under grid-following control condition. When the real-time power P res of the new energy station is greater than the total rated capacity P GFLN of all the converters under grid-following control, the active power instruction of each converter under grid-following control is set to the rated value, and the remaining power P GFM is distributed to the converters under grid-constructing control to be borne by them; P GFM =P res -P GFLN .

16. The follow-the-sun operation output dynamic adjustment method of claim 15, wherein, When the grid strength changes, the rated capacity matching and the running power are re-determined.

17. The follow-the-sun operation output dynamic adjustment method of claim 15, wherein, The grid-connected and grid-forming rated capacity matching system of claim 7 is included. wherein SCR represents the grid strength; P resN is the rated capacity of the new energy station; Z g is the grid impedance; E N is the rated voltage of the point of common coupling; The method for gradually outputting power of the grid-forming converter comprises the following steps:

18. A follow-the-sun-build-out dynamic adjustment system, comprising: Further comprising: The judging module is further configured to acquire real-time power P generated by the new energy station res , and judge the size relationship between the real-time power P generated by the new energy station and the total rated capacity P of all the converters under the grid-following control condition res . GFLN ​ The converter control module is also configured to adjust the active power instruction of all the converters in the grid-constructing control condition to 0 when the real-time power P res of the new energy station is less than or equal to the total rated capacity P GFLN of all the converters in the grid-following control condition; distribute the real-time power P res of the new energy station by the converters in the grid-following control condition when the real-time power P res of the new energy station is greater than the total rated capacity P GFLN of all the converters in the grid-following control condition; set the active power instruction of each converter in the grid-following control condition to the rated value, and distribute the remaining power P GFM to the converters in the grid-constructing control condition to bear; and P GFM =P res -P GFLN . 19.The follow-the-sun-follow-the-sun operation output dynamic adjustment system of claim 18, wherein, The determination module is further configured to determine whether the grid strength changes according to the SCR value of the grid strength, and when the grid strength changes, the rated capacity matching and the running power are re-determined. 20.The follow-the-sun-follow-the-sun operation output dynamic adjustment system of claim 18, wherein, 21. A grid-connected and grid-forming running power dynamic adjustment device, characterized in that it comprises a processor and a memory, and the memory stores computer instructions, and the processor is configured to execute the computer instructions stored in the memory, and when the computer instructions are executed by the processor, the electronic device implements the steps of the grid-connected and grid-forming running power dynamic adjustment method of any one of claims 15 to 17. A power grid strength identification module is configured to collect power grid impedance data and calculate power grid strength by P = E * Z resN where P is the power grid strength; E is the rated voltage of the point of common coupling; and Z is the impedance of the power grid. g P = E * Z N where P is the power grid strength; E is the rated voltage of the point of common coupling; and Z is the impedance of the power grid. The computer readable storage medium stores a computer program, and when the computer program is executed by the processor, the steps of the grid-connected and grid-forming running power dynamic adjustment method of any one of claims 15 to 17 are implemented. ​ 22. A computer-readable storage medium, characterized in that, ​

Images