Capacity configuration method of power electronic grid-connected converter based on grid strength constraints

Abstract

The present application provides a method for configuring the capacity of a power electronic grid-building converter based on grid strength constraints, and relates to the technical field of power system planning. The configuration method includes: evaluating the strength of the grid; judging whether the equivalent inertia time constant of the grid, the short-circuit ratio of multiple stations at the grid-connected point of new energy, and the short-circuit ratio of multiple stations at the end of new energy machines are respectively less than the preset minimum grid inertia time constant requirement value, the minimum requirement value of the short-circuit ratio of multiple stations at the grid-connected point of new energy, and the minimum requirement value of the short-circuit ratio of multiple stations at the end of new energy machines; performing grid compensation on the lowest point of the short-circuit ratio of multiple stations at the grid-connected point of new energy and / or the short-circuit ratio of multiple stations at the end of new energy machines, and determining the first capacity of the power electronic grid-building converter required to be configured; when the capacity of the power electronic grid-building converter meets the safety and stability standards, determining the second capacity of the power electronic grid-building converter required to be configured, and determining the capacity of the power electronic grid-building converter required to be configured in the end according to the first capacity and the second capacity.

Description

Technical Field

[0001] The present application relates to the technical field of power system planning, and in particular to a method for configuring the capacity of a power electronic grid-connected converter based on grid strength constraints. Background Art

[0002] Traditional synchronous units such as thermal power and hydropower not only serve as power sources, but their inherent physical characteristics also play a role in ensuring the stable operation of the power grid, which is the so-called network construction. The network construction capacity is reflected in the strength of the power grid. In the AC power grid, it can be measured by two indicators: system inertia and short-circuit capacity. The former corresponds to the system frequency stability capability, and the latter can characterize the voltage stability capability. The current control mode of new energy such as wind power and photovoltaic power relies on the power grid to provide a benchmark reference. It can only provide the role of power supply and cannot play a similar network construction role as synchronous units.

[0003] Therefore, relying on the flexibility and rapidity of power electronic equipment control, the power electronic grid converter proposed in the industry in recent years has received widespread attention and application. The power electronic grid converter controls the output voltage amplitude and phase, and can provide a constant voltage within a short time scale when faults and disturbances occur. It presents the characteristics of a voltage source as a whole, can increase the inertia and short-circuit capacity of the grid, and provide a grid-forming function similar to that of a synchronous unit. The reasonable application and configuration of the power electronic grid converter can effectively solve the problem of insufficient grid strength in new power systems, and ensure the safe and stable operation after large-scale access to new energy sources while maintaining the basic operating principles and regulations of the existing power grid.

[0004] However, at present, the research focus of power electronic grid-building converters is on control strategies and their improvement, and there is little research on their contribution to grid strength, and there is no clear capacity configuration method. Therefore, it is of positive and practical guiding significance to propose calculation methods and indicators for power electronic grid-building converters to enhance grid strength, and use them as constraints to reasonably and economically configure grid-building converters. Summary of the invention

[0005] In order to solve at least one of the above problems, the present application proposes a method for configuring the capacity of a power electronic grid-connected converter based on grid strength constraints.

[0006] According to the first aspect of the present application, at least one embodiment of the present application provides a method for configuring the capacity of a power electronic grid-connected converter based on grid strength constraints, including: A. evaluating the grid strength, including: calculating the grid equivalent inertia time constant, the short-circuit ratio of multiple stations at new energy grid-connected points, and the short-circuit ratio of multiple stations at new energy machine ends; B. judging whether the grid equivalent inertia time constant, the short-circuit ratio of multiple stations at new energy grid-connected points, and the short-circuit ratio of multiple stations at new energy machine ends are respectively less than the preset minimum grid inertia time constant requirement value, the minimum requirement value of the short-circuit ratio of multiple stations at new energy grid-connected points, and the minimum requirement value of the short-circuit ratio of multiple stations at new energy machine ends; C. when any one of the grid equivalent inertia time constant, the short-circuit ratio of multiple stations at new energy grid-connected points, and the short-circuit ratio of multiple stations at new energy machine ends is less than the minimum grid inertia time constant requirement value, the short-circuit ratio of multiple stations at new energy grid-connected points, and the short-circuit ratio of multiple stations at new energy machine ends In the case of the minimum required value of the short-circuit ratio of the station and the minimum required value of the short-circuit ratio of the multiple stations at the new energy machine end, the short-circuit ratio of the multiple stations at the new energy grid-connected point and / or the minimum short-circuit ratio of the multiple stations at the new energy machine end is compensated for, and the first capacity of the power electronic grid-connected converter required to be configured is determined; D. Determine whether the capacity of the power electronic grid-connected converter meets the preset safety and stability standards; E. In the case that the capacity of the power electronic grid-connected converter does not meet the safety and stability standards, configure a power electronic grid-connected converter with a first typical capacity, and return to step D; F. In the case that the capacity of the power electronic grid-connected converter meets the safety and stability standards, determine the second capacity of the power electronic grid-connected converter required to be configured, and determine the final capacity of the power electronic grid-connected converter required to be configured based on the first capacity and the second capacity.

[0007] For example, in some embodiments of the present application, in step A, the grid equivalent inertia time constant is calculated according to the following formula:

[0008]

[0009] in, H sys is the equivalent inertia time constant of the power grid, , , They represent the inertia time constant, capacity, and operation status of the synchronous generator or synchronous condenser i, respectively. , , They represent the inertia time constant, capacity, and operation status of the power electronic network equipment j with stable energy support capability on the DC side, , , They represent the inertia time constant, capacity and operation status of the asynchronous motor k respectively. is the system load level.

[0010] For example, in some embodiments of the present application, in step A, the short-circuit ratio of multiple stations at the new energy grid connection point and the short-circuit ratio of multiple stations at the new energy machine end are calculated according to the following formula:

[0011]

[0012] in, is the short-circuit ratio of the i-th renewable energy grid connection point / machine terminal multi-station, is the nominal voltage of the i-th grid-connected bus node, is the voltage generated by the grid-connected point / machine-end power generation at the i-th node, The short-circuit current provided for the i-th renewable energy grid connection point / machine end; , It is the self-impedance of node i and the mutual impedance between nodes i / j in the equivalent impedance matrix of the AC power grid after considering the influence of other new energy grid-connected points / machine ends.

[0013] For example, in some embodiments of the present application, in step B, the minimum inertia time constant requirement value of the power grid is calculated according to the following formula:

[0014]

[0015] in, H min is the minimum inertia time constant requirement value of the power grid, is the maximum active unbalance of the power grid under typical fault conditions, It is the maximum frequency change rate that the power grid can withstand.

[0016] For example, in some embodiments of the present application, in step C, it includes: judging whether the short-circuit ratio of multiple stations at the new energy grid-connected point is less than the minimum required value of the short-circuit ratio of multiple stations at the new energy grid-connected point; when the short-circuit ratio of multiple stations at the new energy grid-connected point is less than the minimum required value of the short-circuit ratio of multiple stations at the new energy grid-connected point, sorting the short-circuit ratios of multiple stations at the new energy grid-connected point that are less than the minimum required value of the short-circuit ratio of multiple stations at the new energy grid-connected point, and generating a first sequence of short-circuit ratios of multiple stations at new energy grid-connected points; in the first sequence of short-circuit ratios of multiple stations at new energy grid-connected points, configuring a power electronic grid-connected converter of a first typical capacity at the lowest point of the short-circuit ratio of multiple stations at the new energy grid-connected point, and returning to step A.

[0017] For example, in some embodiments of the present application, in step C, it includes: when the short-circuit ratio of the multiple stations at the new energy grid-connected point is greater than or equal to the minimum required value of the short-circuit ratio of the multiple stations at the new energy grid-connected point, judging whether the short-circuit ratio of the multiple stations at the new energy machine end is less than the minimum required value of the short-circuit ratio of the multiple stations at the new energy machine end; when the short-circuit ratio of the multiple stations at the new energy machine end is less than the minimum required value of the short-circuit ratio of the multiple stations at the new energy machine end, sorting the short-circuit ratios of the multiple stations at the new energy machine end that are less than the minimum required value of the short-circuit ratio of the multiple stations at the new energy machine end to generate a short-circuit ratio sequence of the multiple stations at the new energy machine end; in the short-circuit ratio sequence of the multiple stations at the new energy machine end, configuring the power electronic grid-connected converter of the first typical capacity at the grid-connected point to which the lowest point of the short-circuit ratio of the multiple stations at the new energy machine end belongs, and returning to step A.

[0018] For example, in some embodiments of the present application, in step C, it includes: when the short-circuit ratio of the multi-station at the new energy machine end is greater than or equal to the minimum required value of the short-circuit ratio of the multi-station at the new energy machine end, judging whether the equivalent inertia time constant of the power grid is less than the minimum inertia time constant required value of the power grid; when the equivalent inertia time constant of the power grid is less than the minimum inertia time constant required value of the power grid, sorting the short-circuit ratios of the multi-station at the new energy grid connection point to generate a second sequence of short-circuit ratios of the multi-station at the new energy grid connection point; in the second sequence of short-circuit ratios of the multi-station at the new energy grid connection point, configuring a power electronic grid-connected converter of the first typical capacity at the lowest point of the short-circuit ratio of the multi-station at the new energy grid connection point, and returning to step A.

[0019] For example, in some embodiments of the present application, in step C, it includes: when the equivalent inertia time constant of the power grid is greater than or equal to the minimum inertia time constant requirement value of the power grid, determining the first capacity of the power electronic grid converter to be configured.

[0020] For example, in some embodiments of the present application, the first typical capacity is 50 MVA.

[0021] For example, in some embodiments of the present application, when the capacity of the power electronic grid converter meets the safety and stability standards, the capacity of the power electronic grid converter to be configured is determined according to the first capacity and the second capacity, including: summing the first capacity and the second capacity to determine the capacity of the power electronic grid converter to be configured.

[0022] According to the second aspect of the present application, at least one embodiment of the present application provides an electronic device, comprising: one or more processors; a memory for storing one or more programs; when the one or more programs are executed by the one or more processors, the one or more processors execute a method as described in any one of the first aspects.

[0023] According to a third aspect of the present application, at least one embodiment of the present application provides a computer-readable storage medium having a computer program stored thereon, wherein when the program is executed by a processor, the method as described in any one of the first aspects is implemented.

[0024] Through the above-mentioned example embodiments, the present application provides a method for configuring the capacity of a power electronic grid-building converter based on grid strength constraints, proposes a method for calculating the power electronic grid-building equipment's ability to support grid inertia, especially its ability to support short-circuit capacity under current limiting control; clarifies a quantitative analysis method for the contribution of a power electronic grid-building converter to grid strength, proposes a configuration principle for the capacity of a power electronic grid-building converter based on grid strength constraints, and based on sensitivity analysis, prioritizes grid compensation for the point with the lowest short-circuit ratio at the grid connection point, minimizes the configured capacity as much as possible, and has better economy while ensuring grid stability.

[0025] It should be understood that the foregoing general description and the following detailed description are exemplary only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] By describing in detail exemplary embodiments thereof with reference to the accompanying drawings, the above and other objects, features and advantages of the present application will become more apparent. The accompanying drawings described below are only some embodiments of the present application, and are not intended to limit the present application.

[0027] Figure 1 A flow chart showing a method for configuring power electronic grid converter capacity based on grid strength constraints according to an exemplary embodiment;

[0028] Figure 2 A flow chart showing a capacity configuration iteration phase of an exemplary embodiment;

[0029] Figure 3 A structural diagram of an electronic device provided by the present application is shown. DETAILED DESCRIPTION

[0030] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this application will be comprehensive and complete and will fully convey the concepts of the example embodiments to those skilled in the art. The same reference numerals in the figures represent the same or similar parts, and thus their repeated description will be omitted.

[0031] The described features, structures or characteristics may be combined in one or more embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present disclosure. However, those skilled in the art will appreciate that the technical solutions of the present disclosure may be practiced without one or more of these specific details, or other modes, components, materials, devices, etc. may be adopted. In these cases, known structures, methods, devices, implementations, materials or operations will not be shown or described in detail.

[0032] The flowcharts shown in the accompanying drawings are only exemplary and do not necessarily include all the contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps can be decomposed, and some operations / steps can be combined or partially combined, so the actual execution order may change according to actual conditions.

[0033] The terms "first", "second", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices.

[0034] Those skilled in the art will appreciate that the drawings are merely schematic diagrams of example embodiments, and the modules or processes in the drawings are not necessarily necessary for implementing the present application, and therefore cannot be used to limit the scope of protection of the present application.

[0035] Figure 1 A flow chart of a method for configuring power electronic grid converter capacity based on grid strength constraints according to an exemplary embodiment is shown.

[0036] like Figure 1 As shown, the method for configuring the capacity of a power electronic grid-connected converter based on grid strength constraints includes steps S101-S106.

[0037] In step S101, the grid strength is evaluated, including: calculating the grid equivalent inertia time constant, the short-circuit ratio of multiple stations at the new energy grid connection point, and the short-circuit ratio of multiple stations at the new energy machine end.

[0038] According to some embodiments, the grid strength is evaluated based on the grid architecture, power supply configuration, load distribution, etc. under various typical modes, including: the grid equivalent inertia time constant, the short-circuit ratio of multiple stations at new energy grid connection points, and the short-circuit ratio of multiple stations at new energy machine ends in new energy stations.

[0039] Calculate the equivalent inertia time constant of the power grid according to the following formula:

[0040]

[0041] in, H sys is the equivalent inertia time constant of the power grid, , , They represent the inertia time constant, capacity, and operation status of the synchronous generator or synchronous condenser i, respectively. , , They represent the inertia time constant, capacity, and operation status of the power electronic network equipment j with stable energy support capability on the DC side, , , They represent the inertia time constant, capacity and operation status of the asynchronous motor k respectively. is the system load level.

[0042] The short-circuit ratio of multiple stations at new energy grid connection points is calculated according to the following formula:

[0043]

[0044] in, is the short-circuit ratio of multiple stations at the i-th renewable energy grid connection point, is the nominal voltage of the ith grid-connected bus node, is the voltage generated by the grid-connected power at the i-th node, The short-circuit current provided for the i-th renewable energy grid connection point; , This is the self-impedance of node i and the mutual impedance between nodes i / j in the equivalent impedance matrix of the AC power grid after considering the influence of other renewable energy grid-connected points.

[0045] Calculate the short-circuit ratio of multiple stations at the new energy machine end according to the following formula:

[0046]

[0047] in, The short-circuit ratio of multiple stations at the i-th new energy machine end, is the nominal voltage of the ith grid-connected bus node, is the voltage generated by the power generated by the machine at the i-th node, The short-circuit current provided for the i-th new energy machine terminal; , It is the self-impedance of node i and the mutual impedance between nodes i / j in the equivalent impedance matrix of the AC power grid after considering the influence of other new energy machines.

[0048] In step S102, it is determined whether the equivalent inertia time constant of the power grid, the short-circuit ratio of multiple stations at the new energy grid connection point, and the short-circuit ratio of multiple stations at the new energy machine end are respectively less than the preset minimum inertia time constant requirement value of the power grid, the minimum requirement value of the short-circuit ratio of multiple stations at the new energy grid connection point, and the minimum requirement value of the short-circuit ratio of multiple stations at the new energy machine end.

[0049] According to some embodiments, the grid minimum inertia time constant requirement It should be considered that under various typical modes, the grid frequency change rate (RoCoF) after serious faults such as DC interlocking, power center collection line N-1, and load center collection line N-1 should not exceed the limit value and should not trigger the third line of defense action.

[0050] And calculate the minimum inertia time constant requirement of the power grid according to the following formula:

[0051]

[0052] in, H min is the minimum inertia time constant requirement value of the power grid, is the maximum active unbalance of the power grid under typical fault conditions, It is the maximum frequency change rate that the power grid can withstand.

[0053] According to some embodiments, the maximum frequency change rate that the power grid can withstand usually takes into account two factors: the RoCoF tolerance of conventional units in the system and the anti-islanding protection action setting value of distributed power sources. Among them, the RoCoF tolerance of conventional units is generally recommended not to exceed 2Hz / s, otherwise the synchronous machine will cause pole slippage, which will cause damage to the internal mechanism of the synchronous machine; in order to prevent the distributed power source from being disconnected from the grid after a disturbance, the RoCoF shall not exceed its anti-islanding protection setting value.

[0054] According to relevant national standards, the minimum required values ​​for the short-circuit ratio of multiple stations at new energy grid-connected points and the minimum required values ​​for the short-circuit ratio of multiple stations at new energy machine ends are 2.0 and 1.5 respectively.

[0055] In step S103, in the capacity configuration iteration link: when any one of the equivalent inertia time constant of the power grid, the short-circuit ratio of multiple stations at the new energy grid connection point, and the short-circuit ratio of multiple stations at the new energy machine end is less than the minimum inertia time constant requirement value of the power grid, the minimum requirement value of the short-circuit ratio of multiple stations at the new energy grid connection point, and the minimum requirement value of the short-circuit ratio of multiple stations at the new energy machine end, the short-circuit ratio of multiple stations at the new energy grid connection point and / or the short-circuit ratio of multiple stations at the new energy machine end is compensated for the lowest point, a power electronic grid converter of the first typical capacity is configured, and the process returns to step S101;

[0056] When the equivalent inertia time constant of the power grid is greater than or equal to the minimum inertia time constant requirement value of the power grid, the short-circuit ratio of multiple stations at the new energy grid-connected point is greater than or equal to the minimum requirement value of the short-circuit ratio of multiple stations at the new energy grid-connected point, and the short-circuit ratio of multiple stations at the new energy machine end is greater than or equal to the minimum requirement value of the short-circuit ratio of multiple stations at the new energy machine end, the first capacity of the power electronic grid converter to be configured is determined according to the number of power electronic grid converters of the first typical capacity configured in the capacity configuration iteration link.

[0057] The equivalent inertia time constant of the power grid determines the frequency stability capability, especially directly related to the maximum frequency change rate. Inertia support consumes energy and requires the equipment to have a certain energy support capability. Therefore, the power electronic grid converter with stable energy support capability on the DC side can provide inertia support to the power grid.

[0058] The short-circuit capacity of the power grid is essentially a measure of the electrical distance between the voltage source and the equipment. The closer the electrical distance, the stronger the voltage stability capability. The power electronic grid converter takes into account the overcurrent capacity of the device and adopts a current limiting design (typical design is 3 times 10s). However, when calculating its short-circuit capacity contribution capability, it should be made clear that its electrical distance from the equipment has nothing to do with the overcurrent capacity. In addition, the internal impedance of the power electronic grid converter is 0.12pu under the typical design, and the two-stage boost transformer impedance to the grid connection point is 0.22pu in total. Even if a serious three-phase metal grounding short circuit occurs at the grid connection point of the power electronic grid converter (the closest electrical distance point in the external system), the short-circuit current is still less than 3 times the rated value and has not yet reached its current limiting action threshold. Therefore, the calculation method of the power electronic grid converter's contribution to short-circuit capacity / short-circuit ratio can be regarded as consistent with that of traditional generators / phase regulators.

[0059] According to an example embodiment, Figure 2 As shown, network compensation is performed on the lowest point of the short-circuit ratio of multiple stations at the new energy grid connection point and / or the short-circuit ratio of multiple stations at the new energy machine end, that is, the capacity configuration iteration link, including steps S1031-S1030.

[0060] In step S1031, it is determined whether the short-circuit ratio of multiple stations at the new energy grid-connected point is less than the minimum required value of the short-circuit ratio of multiple stations at the new energy grid-connected point.

[0061] In step S1032, when the short-circuit ratio of multiple stations at new energy grid connection points is less than the minimum required value of the short-circuit ratio of multiple stations at new energy grid connection points, the short-circuit ratios of multiple stations at new energy grid connection points that are less than the minimum required value of the short-circuit ratio of multiple stations at new energy grid connection points are sorted to generate a first sequence of short-circuit ratios of multiple stations at new energy grid connection points.

[0062] In step S1033, in the first sequence of short-circuit ratios of multiple stations at new energy grid-connected points, a power electronic grid-connected converter of the first typical capacity is configured at the lowest point of the short-circuit ratios of multiple stations at new energy grid-connected points, and the process returns to step S101.

[0063] According to some embodiments, the first typical capacity is 50 MVA.

[0064] According to some embodiments, in this application, priority is given to performing grid compensation at the point where the short-circuit ratio of the new energy multi-station is the lowest. The reason is that: assuming that the power electronic grid converter is connected at the network node m, the system impedance matrix will change, and any element in the new matrix can be expressed as:

[0065]

[0066] Among them, those without superscripts are the original AC power grid equivalent impedance matrix elements, and those with superscripts are the new matrix elements. is the impedance of the power electronic grid converter system. Substitute the above formula into the calculation formula of the short-circuit ratio of multiple stations at the new energy grid connection point and / or the short-circuit ratio of multiple stations at the new energy machine end, and Z mi The derivative is always greater than 0, that is, the lower the short-circuit ratio of the new energy multi-station, the greater the increase in the short-circuit ratio of all new energy nodes. Therefore, it is preferred to perform network compensation at the point where the short-circuit ratio of the new energy multi-station is low.

[0067] In step S1034, when the short-circuit ratio of multiple stations at the new energy grid connection point is greater than or equal to the minimum required value of the short-circuit ratio of multiple stations at the new energy grid connection point, it is determined whether the short-circuit ratio of multiple stations at the new energy machine end is less than the minimum required value of the short-circuit ratio of multiple stations at the new energy machine end.

[0068] In step S1035, when the short-circuit ratio of multiple stations at the new energy machine end is less than the minimum required value of the short-circuit ratio of multiple stations at the new energy machine end, the short-circuit ratios of multiple stations at the new energy machine end that are less than the minimum required value of the short-circuit ratio of multiple stations at the new energy machine end are sorted to generate a short-circuit ratio sequence of multiple stations at the new energy machine end.

[0069] In step S1036, in the short-circuit ratio sequence of multiple stations at the new energy machine end, a power electronic grid converter of the first typical capacity is configured at the grid connection point to which the lowest point of the short-circuit ratio of multiple stations at the new energy machine end belongs, and the process returns to step S101.

[0070] According to some embodiments, when the short-circuit ratio of multiple stations at the new energy machine end does not meet the requirements, the reason for performing network compensation at the grid connection point is that the number of new energy sources is large and the capacity of a single machine is small. If compensation is performed at the machine end, the typical capacity is relatively large. Compensation at the grid connection point where the short-circuit ratio at the machine end is the lowest can improve the short-circuit ratio of multiple machine ends in the entire station.

[0071] In step S1037, when the short-circuit ratio of the new energy machine end multi-station is greater than or equal to the minimum required value of the short-circuit ratio of the new energy machine end multi-station, it is determined whether the equivalent inertia time constant of the power grid is less than the minimum required value of the inertia time constant of the power grid.

[0072] In step S1038, when the equivalent inertia time constant of the power grid is less than the minimum inertia time constant requirement value of the power grid, the short-circuit ratios of multiple stations of the new energy grid connection points are sorted to generate a second sequence of short-circuit ratios of multiple stations of the new energy grid connection points.

[0073] In step S1039, in the second sequence of short-circuit ratios of multiple stations at new energy grid-connected points, a power electronic grid-connected converter of the first typical capacity is configured at the lowest point of the short-circuit ratios of multiple stations at new energy grid-connected points, and the process returns to step S101.

[0074] According to some embodiments, when the equivalent inertia time constant of the power grid does not meet the requirements, the reason for performing network compensation at the lowest point of the grid connection point is that: inertia compensation has no requirements for the compensation position and has global characteristics. Performing network compensation at the lowest point of the grid connection point can not only improve the equivalent inertia time constant of the entire network, but also maximize the short-circuit ratio of multiple new energy stations.

[0075] In step S1030, when the grid equivalent inertia time constant is greater than or equal to the grid minimum inertia time constant requirement value, the first capacity S of the power electronic grid converter to be configured is determined. 1 .

[0076] In step S104, it is determined whether the capacity of the power electronic grid converter meets the preset safety and stability standards.

[0077] According to the exemplary embodiment, the grid is reinforced according to the first capacity determined in step S103, a temporary stability check under a typical fault is carried out, and it is determined whether the capacity of the power electronic grid converter meets the safety and stability standards.

[0078] In step S105, in the grid stability verification phase: when the capacity of the power electronic grid-building converter does not meet the safety and stability standards, a power electronic grid-building converter of a first typical capacity is configured.

[0079] According to the example embodiment, in the grid stability verification phase: according to step S103, the first capacity is determined to perform grid reinforcement. If the safety and stability standards are not met, a power electronic grid converter of the first typical capacity is configured, and the process returns to step S104.

[0080] According to some embodiments, temporary stability checks under typical faults mainly include: nearby DC commutation failure, single-pole lockout, AC line N-1, main transformer N-1 and other fault types, and the assessment criteria include frequency, voltage and power angle stability.

[0081] In step S106, when the capacity of the power electronic grid converter meets the safety and stability standards, the second capacity S of the power electronic grid converter to be configured is determined according to the number of power electronic grid converters of the first typical capacity configured in the grid stability verification link. 2 The first capacity and the second capacity are summed to determine the capacity of the power electronic grid converter to be configured.

[0082] According to an exemplary embodiment, when the capacity of the power electronic grid converter meets the safety and stability standards, the first capacity S required in the capacity configuration iteration phase is determined. 1 and the second capacity S required for the grid stability verification link 2 , and the first capacity S 1 and the second capacity S 2 Sum them up and determine the capacity of the power electronic grid converter that is ultimately required.

[0083] The present application provides a method for configuring the capacity of a power electronic grid-building converter based on grid strength constraints, proposes a method for calculating the power electronic grid-building equipment's ability to support grid inertia, especially its ability to support short-circuit capacity under current limiting control; clarifies a quantitative analysis method for the contribution of a power electronic grid-building converter to grid strength, proposes a configuration principle for the capacity of a power electronic grid-building converter based on grid strength constraints, and based on sensitivity analysis, prioritizes grid compensation for the point with the lowest short-circuit ratio at the grid connection point, minimizes the configured capacity as much as possible, and has better economy while ensuring grid stability.

[0084] Figure 3 A structural diagram of an electronic device provided by the present application is shown.

[0085] See also Figure 3 , Figure 3 An electronic device is provided, comprising a processor and a memory. The memory stores computer instructions. When the computer instructions are executed by the processor, the processor executes the computer instructions to achieve the following Figure 1 or Figure 2 The method and refinement scheme shown.

[0086] It should be understood that the above-mentioned device embodiments are only illustrative, and the device disclosed in the present application can also be implemented in other ways. For example, the division of units / modules in the above-mentioned embodiments is only a logical function division, and there may be other division methods in actual implementation. For example, multiple units, modules or components can be combined, or can be integrated into another system, or some features can be ignored or not executed.

[0087] In addition, unless otherwise specified, each functional unit / module in each embodiment of the present application may be integrated into one unit / module, each unit / module may exist physically separately, or two or more units / modules may be integrated together. The above-mentioned integrated unit / module may be implemented in the form of hardware or in the form of a software program module.

[0088] If the integrated unit / module is implemented in the form of hardware, the hardware may be a digital circuit, an analog circuit, etc. The physical implementation of the hardware structure includes but is not limited to transistors, memristors, etc. Unless otherwise specified, the processor or chip may be any appropriate hardware processor, such as CPU, GPU, FPGA, DSP, and ASIC, etc. Unless otherwise specified, the on-chip cache, off-chip memory, and storage may be any appropriate magnetic storage medium or magneto-optical storage medium, such as Resistive Random Access Memory (RRAM), Dynamic Random Access Memory (DRAM), Static Random-Access Memory (SRAM), Enhanced Dynamic Random Access Memory (EDRAM), High-Bandwidth Memory (HBM), Hybrid Memory Cube (HMC), etc.

[0089] If the integrated unit / module is implemented in the form of a software program module and sold or used as an independent product, it can be stored in a computer-readable memory. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, which is stored in a memory and includes several instructions for a computer device (which can be a personal computer, server or network device, etc.) to execute all or part of the steps of the various embodiments of the present disclosure. The aforementioned memory includes: U disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), mobile hard disk, disk or optical disk and other media that can store program codes.

[0090] The present application also provides a non-transitory computer storage medium storing a computer program. When the computer program is executed by multiple processors, the processors execute the following Figure 1 or Figure 2 The method and refinement scheme shown.

[0091] It should be clearly understood that the present application describes how to form and use specific examples, but the present application is not limited to any details of these examples. On the contrary, based on the teaching of the content disclosed in the present application, these principles can be applied to many other embodiments.

[0092] In addition, it should be noted that the above figures are only schematic illustrations of the processes included in the method according to the exemplary embodiments of the present application, and are not intended to be limiting. It is easy to understand that the processes shown in the above figures do not indicate or limit the time sequence of these processes. In addition, it is also easy to understand that these processes can be performed synchronously or asynchronously, for example, in multiple modules.

[0093] The exemplary embodiments of the present application are specifically shown and described above. It should be understood that the present application is not limited to the detailed structures, configurations or implementations described herein; on the contrary, the present application is intended to cover various modifications and equivalent configurations included in the spirit and scope of the appended claims.

Claims

1. A method for configuring the capacity of a power electronic grid-connected converter based on grid strength constraints, characterized in that: include: A. Evaluate the strength of the power grid, including: calculating the equivalent inertia time constant of the power grid, the short-circuit ratio of multiple stations at the new energy grid connection point, and the short-circuit ratio of multiple stations at the new energy machine end; B. Determine whether the equivalent inertia time constant of the power grid, the short-circuit ratio of multiple stations at the new energy grid connection point, and the short-circuit ratio of multiple stations at the new energy machine end are respectively less than the preset minimum inertia time constant requirement value of the power grid, the minimum requirement value of the short-circuit ratio of multiple stations at the new energy grid connection point, and the minimum requirement value of the short-circuit ratio of multiple stations at the new energy machine end; C. Capacity configuration iteration link: when any one of the equivalent inertia time constant of the power grid, the short-circuit ratio of multiple stations at the new energy grid connection point, and the short-circuit ratio of multiple stations at the new energy machine end is less than the minimum inertia time constant requirement value of the power grid, the minimum requirement value of the short-circuit ratio of multiple stations at the new energy grid connection point, and the minimum requirement value of the short-circuit ratio of multiple stations at the new energy machine end, network compensation is performed on the lowest point of the short-circuit ratio of multiple stations at the new energy grid connection point and / or the short-circuit ratio of multiple stations at the new energy machine end, a power electronic network converter of the first typical capacity is configured, and the process returns to step A; In the case where the equivalent inertia time constant of the power grid is greater than or equal to the minimum inertia time constant requirement value of the power grid, the short-circuit ratio of multiple stations at the new energy grid connection point is greater than or equal to the minimum requirement value of the short-circuit ratio of multiple stations at the new energy grid connection point, and the short-circuit ratio of multiple stations at the new energy machine end is greater than or equal to the minimum requirement value of the short-circuit ratio of multiple stations at the new energy machine end, the first capacity of the power electronic grid converter to be configured is determined according to the number of power electronic grid converters of the first typical capacity configured in the capacity configuration iteration link; D. Determine whether the capacity of the power electronic grid converter meets the preset safety and stability standards; E. Grid stability verification step: when the capacity of the power electronic grid-building converter does not meet the safety and stability standards, configure a power electronic grid-building converter of a first typical capacity, and return to step D; F. When the capacity of the power electronic grid-building converter meets the safety and stability standards, the second capacity of the power electronic grid-building converter required to be configured is determined according to the number of power electronic grid-building converters of the first typical capacity configured in the grid stability verification link, and the first capacity and the second capacity are summed to determine the final capacity of the power electronic grid-building converter required to be configured.

2. The configuration method according to claim 1, characterized in that: In step A, the grid equivalent inertia time constant is calculated according to the following formula: in, H sys is the equivalent inertia time constant of the power grid, , , They represent the inertia time constant, capacity, and operation status of the synchronous generator or synchronous condenser i, respectively. , , They represent the inertia time constant, capacity, and operation status of the power electronic network equipment j with stable energy support capability on the DC side, , , They represent the inertia time constant, capacity and operation status of the asynchronous motor k respectively. is the system load level.

3. The configuration method according to claim 1, characterized in that: In step A, the short-circuit ratio of multiple stations at the new energy grid connection point and the short-circuit ratio of multiple stations at the new energy machine end are calculated according to the following formula: in, is the short-circuit ratio of the i-th renewable energy grid connection point / machine terminal multi-station, is the nominal voltage of the i-th grid-connected bus node, is the voltage generated by the grid-connected point / machine-end power generation at the i-th node, The short-circuit current provided for the i-th renewable energy grid connection point / machine end; , It is the self-impedance of node i and the mutual impedance between nodes i / j in the equivalent impedance matrix of the AC power grid after considering the influence of other new energy grid-connected points / machine ends.

4. The configuration method according to claim 1, characterized in that: In step B, the minimum inertia time constant requirement value of the power grid is calculated according to the following formula: in, H min is the minimum inertia time constant requirement value of the power grid, is the maximum active unbalance of the power grid under typical fault conditions, It is the maximum frequency change rate that the power grid can withstand.

5. The configuration method according to claim 1, characterized in that: In step C, it includes: Determining whether the short-circuit ratio of multiple stations at the new energy grid connection point is less than the minimum required value of the short-circuit ratio of multiple stations at the new energy grid connection point; In the case where the short-circuit ratio of multiple stations at the new energy grid connection point is less than the minimum required value of the short-circuit ratio of multiple stations at the new energy grid connection point, the short-circuit ratios of multiple stations at the new energy grid connection point that are less than the minimum required value of the short-circuit ratio of multiple stations at the new energy grid connection point are sorted to generate a first sequence of short-circuit ratios of multiple stations at the new energy grid connection point; In the first sequence of short-circuit ratios of multiple stations at new energy grid-connected points, a power electronic grid-connected converter of the first typical capacity is configured at the lowest point of the short-circuit ratios of multiple stations at new energy grid-connected points, and the process returns to step A.

6. The configuration method according to claim 5, characterized in that: In step C, it includes: When the short-circuit ratio of multiple stations at the new energy grid connection point is greater than or equal to the minimum required value of the short-circuit ratio of multiple stations at the new energy grid connection point, determining whether the short-circuit ratio of multiple stations at the new energy machine end is less than the minimum required value of the short-circuit ratio of multiple stations at the new energy machine end; In the case where the short-circuit ratio of the new energy machine-end multi-station is less than the minimum required value of the short-circuit ratio of the new energy machine-end multi-station, the short-circuit ratios of the new energy machine-end multi-station that are less than the minimum required value of the short-circuit ratio of the new energy machine-end multi-station are sorted to generate a short-circuit ratio sequence of the new energy machine-end multi-station; In the short-circuit ratio sequence of multiple stations at the new energy machine end, the power electronic grid converter of the first typical capacity is configured at the grid connection point to which the lowest point of the short-circuit ratio of multiple stations at the new energy machine end belongs, and return to step A.

7. The configuration method according to claim 6, characterized in that: In step C, it includes: When the short-circuit ratio of the new energy machine-end multi-station is greater than or equal to the minimum required value of the short-circuit ratio of the new energy machine-end multi-station, judging whether the equivalent inertia time constant of the power grid is less than the minimum required value of the inertia time constant of the power grid; When the equivalent inertia time constant of the power grid is less than the minimum inertia time constant requirement value of the power grid, the short-circuit ratios of multiple stations of the new energy grid connection points are sorted to generate a second sequence of short-circuit ratios of multiple stations of the new energy grid connection points; In the second sequence of short-circuit ratios of multiple stations at new energy grid-connected points, a power electronic grid-connected converter of the first typical capacity is configured at the lowest point of the short-circuit ratios of multiple stations at new energy grid-connected points, and the process returns to step A.

8. The configuration method according to claim 7, characterized in that: In step C, it includes: In a case where the equivalent inertia time constant of the power grid is greater than or equal to the minimum inertia time constant requirement value of the power grid, a first capacity of the power electronic grid converter to be configured is determined.

9. The configuration method according to any one of claims 1 or 5-8, characterized in that: The first typical capacity is 50MVA.

10. The configuration method according to claim 1, characterized in that: When the capacity of the power electronic grid converter meets the safety and stability standard, determining the capacity of the power electronic grid converter to be configured according to the first capacity and the second capacity includes: The first capacity and the second capacity are summed to determine the capacity of the power electronic grid converter to be configured.

11. An electronic device, characterized in that: include: one or more processors; A memory for storing one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors execute the method according to any one of claims 1 to 10.

12. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the method according to any one of claims 1 to 10 is implemented.

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