Configuration method for constructing network and storing energy in island power grid

Abstract

The invention relates to a configuration method for constructing network energy storage in an isolated island power grid, the isolated island power grid comprises a plurality of off-grid electric fields, and the method comprises the following steps: acquiring a multi-station short-circuit ratio of a boost transformer low-voltage side of a power generation unit in the plurality of off-grid electric fields and a multi-station short-circuit ratio of a grid-connected point corresponding to each of the plurality of off-grid electric fields; in the power generation unit boost transformer low-voltage side multi-station short-circuit ratio and the grid-connected point multi-station short-circuit ratio, there is a multi-station short-circuit ratio which does not satisfy a preset condition, and the plurality of off-grid electric fields are not configured with grid-construction energy storage, the power generation unit boost transformer low-voltage side multi-station short-circuit ratio and the grid-connected point multi-station short-circuit ratio are not configured. And determining the configuration of network construction energy storage in the off-network electric field corresponding to the minimum grid-connected point multi-station short-circuit ratio. According to the method provided by the invention, the effect of improving the multi-station short-circuit ratio of the off-grid electric field is the most obvious, the selected network construction energy storage capacity not only can meet the requirement of stable operation of the off-grid electric field, but also can consider the energy storage construction and maintenance cost, and the technical and economic consideration during network construction energy storage configuration is balanced.

Description

Technical Field

[0001] The present application relates to the technical field of energy storage, and particularly to a method for configuring network-forming energy storage in an island power grid. Background Art

[0002] At present, with the rapid development of offshore wind power, off-grid power plants in island power grids provide stable power supply for it. However, the volatility and randomness of off-grid power plants pose challenges to the stable operation of island power grids. The application of network-forming energy storage technology can not only effectively suppress the fluctuations of off-grid wind farms in island power grids, but also improve the operation stability of island power grids, providing the necessary grid strength for the stable operation of off-grid power plants.

[0003] Although network-forming energy storage can effectively improve the grid strength of island power grids and the operation efficiency of off-grid power plants, the construction and maintenance costs of network-forming energy storage are relatively high, and reasonable configuration is required. In existing solutions, the capacity configuration schemes considering network-forming energy storage are relatively single, mostly the configuration methods for the capacity of a single set of network-forming energy storage, and all research points including the low-voltage side of the step-up transformer of the generating unit in the off-grid power plant are not investigated. Summary of the Invention

[0004] In view of the above problems in the prior art, according to the first aspect of the present application, a method for configuring network-forming energy storage in an island power grid is provided, including:

[0005] Obtaining the multi-station short-circuit ratio of the low-voltage side of the step-up transformer of the generating unit in the plurality of off-grid power plants and the multi-station short-circuit ratio of the grid connection points corresponding to the plurality of off-grid power plants respectively; and

[0006] When there is a multi-station short-circuit ratio that does not meet the preset condition among the multi-station short-circuit ratio of the low-voltage side of the step-up transformer of the generating unit and the multi-station short-circuit ratio of the grid connection point, and none of the plurality of off-grid power plants is configured with network-forming energy storage, determining to configure network-forming energy storage in the off-grid power plant corresponding to the minimum multi-station short-circuit ratio of the grid connection point.

[0007] According to some embodiments, the method further includes:

[0008] When there is a multi-station short-circuit ratio that does not meet the preset condition among the multi-station short-circuit ratio of the low-voltage side of the step-up transformer of the generating unit and the multi-station short-circuit ratio of the grid connection point, and there is network-forming energy storage configured in the plurality of off-grid power plants, determining whether the preset capacity currently corresponding to the configured network-forming energy storage reaches the maximum preset capacity;

[0009] In the case where it is determined that the currently corresponding preset capacity of the configured grid-forming energy storage does not reach the maximum preset capacity, determine the next preset capacity within the capacity range of the configured grid-forming energy storage as the current preset capacity, where the next preset capacity is greater than the currently corresponding preset capacity; and

[0010] Calculate the multi-station short-circuit ratio of the low-voltage side of the step-up transformer of the power generation unit in the multiple off-grid power plants and the multi-station short-circuit ratio of the grid connection point corresponding to each of the multiple off-grid power plants according to the current preset capacity.

[0011] According to some embodiments, the method further includes:

[0012] In the case where it is determined that the currently corresponding preset capacity of the configured grid-forming energy storage reaches the maximum preset capacity, determine the off-grid power plant corresponding to the minimum multi-station short-circuit ratio of the grid connection point in the off-grid power plants without configured grid-forming energy storage as the off-grid power plant to be configured with grid-forming energy storage; and

[0013] Configure grid-forming energy storage for the off-grid power plant to be configured with grid-forming energy storage.

[0014] According to some embodiments, obtaining the multi-station short-circuit ratio of the low-voltage side of the step-up transformer of the power generation unit in the multiple off-grid power plants and the multi-station short-circuit ratio of the grid connection point corresponding to each of the multiple off-grid power plants includes:

[0015] Obtain the planned operation parameters of the island power grid;

[0016] Establish a circuit model of the island power grid according to the planned operation parameters; and

[0017] Obtain the multi-station short-circuit ratio of the low-voltage side of the step-up transformer of the power generation unit in the multiple off-grid power plants and the multi-station short-circuit ratio of the grid connection point corresponding to each of the multiple off-grid power plants according to the circuit model.

[0018] According to some embodiments, obtaining the multi-station short-circuit ratio of the low-voltage side of the step-up transformer of the power generation unit in the multiple off-grid power plants and the multi-station short-circuit ratio of the grid connection point corresponding to each of the multiple off-grid power plants according to the circuit model includes:

[0019] Obtain the multi-port equivalent model of the island power grid according to the circuit model;

[0020] Obtain the impedance matrix and short-circuit capacity of the low-voltage side of the step-up transformer of the power generation unit, the impedance matrix and short-circuit capacity of the grid connection point, the active power of the power generation unit, and the active power of the off-grid power plant according to the multi-port equivalent model; and

[0021] Calculate the multi-station short-circuit ratio of the low-voltage side of the step-up transformer of the power generation unit in the multiple off-grid power plants and the multi-station short-circuit ratio of the connection points corresponding to the multiple off-grid power plants according to the impedance matrix and short-circuit capacity of the low-voltage side of the step-up transformer of the power generation unit, the impedance matrix and short-circuit capacity of the connection point, the active power of the power generation unit, and the active power of the off-grid power plant.

[0022] According to some embodiments, the determining to configure a network-forming energy storage in the off-grid power plant corresponding to the minimum multi-station short-circuit ratio of the connection point includes:

[0023] Determine the capacity range of the configured network-forming energy storage, where the capacity range includes multiple preset capacities;

[0024] Select a preset capacity within the capacity range as the capacity of the configured network-forming energy storage; and

[0025] Calculate the multi-station short-circuit ratio of the low-voltage side of the step-up transformer of the power generation unit in the multiple off-grid power plants and the multi-station short-circuit ratio of the connection points corresponding to the multiple off-grid power plants according to the selected preset capacity.

[0026] According to some embodiments, the configuring a network-forming energy storage for the off-grid power plant to be configured with a network-forming energy storage includes:

[0027] Determine the capacity range of the configured network-forming energy storage, where the capacity range includes multiple preset capacities;

[0028] Select a preset capacity within the capacity range as the capacity of the configured network-forming energy storage; and

[0029] Calculate the multi-station short-circuit ratio of the low-voltage side of the step-up transformer of the power generation unit in the multiple off-grid power plants and the multi-station short-circuit ratio of the connection points corresponding to the multiple off-grid power plants according to the selected preset capacity.

[0030] According to the second aspect of the present application, there is provided a device for configuring a network-forming energy storage in an island power grid, including:

[0031] A multi-station short-circuit ratio acquisition module, configured to acquire the multi-station short-circuit ratio of the low-voltage side of the step-up transformer of the power generation unit in the multiple off-grid power plants and the multi-station short-circuit ratio of the connection points corresponding to the multiple off-grid power plants; and

[0032] A network-forming energy storage configuration module, configured to determine to configure a network-forming energy storage in the off-grid power plant corresponding to the minimum multi-station short-circuit ratio of the connection point when there is a multi-station short-circuit ratio that does not meet the preset conditions among the multi-station short-circuit ratio of the low-voltage side of the step-up transformer of the power generation unit and the multi-station short-circuit ratio of the connection point, and none of the multiple off-grid power plants are configured with a network-forming energy storage.

[0033] According to a third aspect of the present application, there is provided an electronic device, including a memory and a processor. A computer program is stored on the memory, and when the processor executes the computer program on the memory, the method described in the first aspect is implemented.

[0034] According to a fourth aspect of the present application, there is provided a computer-readable storage medium, characterized in that the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method described in the first aspect is implemented.

[0035] According to the method for configuring network-forming energy storage in an island power grid proposed in the present application, by starting to configure network-forming energy storage from an off-grid power plant corresponding to the short-circuit ratio of multiple power plants at the minimum grid connection point, the effect of improving the short-circuit ratio of multiple power plants of the off-grid power plant can be made the most obvious. At the same time, the problem of the off-grid power plant with the most serious non-compliance of the short-circuit ratio of multiple power plants with the preset conditions can be solved preferentially. Through the method for configuring network-forming energy storage in an island power grid provided by the present application, the selected network-forming energy storage capacity can not only meet the needs of the stable operation of the off-grid power plant, but also take into account the construction and maintenance costs of the energy storage, providing a basis for the technical and economic considerations of the network-forming energy storage capacity configuration of the off-grid power plant. This method balances the technical and economic considerations of the network-forming energy storage capacity configuration of the off-grid power plant, providing a new idea for the network-forming energy storage capacity configuration of the off-grid power plant in the power grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can also be obtained according to these drawings without exceeding the scope required to be protected by the present application.

[0037] Figure 1 It is a schematic diagram of the circuit model of an island power grid according to an embodiment of the present application.

[0038] Figure 2 It is a flowchart of the method for configuring network-forming energy storage in an island power grid according to an embodiment of the present application.

[0039] Figure 3 It is a flowchart of the method for configuring network-forming energy storage in an island power grid according to another embodiment of the present application.

[0040] Figure 4 It is a flowchart of the method for configuring network-forming energy storage in an island power grid according to still another embodiment of the present application.

[0041] Figure 5 It is a schematic diagram of the device for configuring network-forming energy storage in an island power grid according to an embodiment of the present application.

[0042] Figure 6 This is a structural diagram of an electronic device provided by the present application.

[0043] Reference numerals: 1 off-grid electric field, 2 other parts of the island power grid, 11 power generation unit, 12 step-up transformer for power generation unit, 13 step-up transformer for collection station, 14 grid connection point, 15 grid-forming energy storage. Detailed implementation manners

[0044] Next, the technical solutions in the embodiments of the present application will be clearly and completely described with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts fall within the protection scope of the present application.

[0045] Figure 1 This is a schematic diagram of the circuit model of an island power grid according to an embodiment of the present application. As Figure 1 shown, the island power grid includes multiple off-grid electric fields, and the multiple off-grid electric fields provide stable power supply for the island power grid. According to one embodiment, the multiple off-grid electric fields are all off-grid wind farms.

[0046] According to some embodiments, the off-grid electric field includes a power generation unit, a step-up transformer for the power generation unit, a step-up transformer for the collection station, a grid connection point, and grid-forming energy storage. Among them, the number of power generation units and step-up transformers for power generation units in each off-grid electric field can be set to one or more according to the actual needs of the off-grid electric field, and the number of collection stations and grid connection points in each off-grid electric field is one respectively. According to one embodiment, the number of power generation units and step-up transformers for power generation units in one off-grid electric field is both two.

[0047] According to one aspect of the present application, a method for configuring grid-forming energy storage in an island power grid is provided. As Figure 2 shown, the method includes the following steps.

[0048] Step S201, obtain the short-circuit ratios of multiple power generation unit low-voltage sides of multiple off-grid electric fields and the short-circuit ratios of multiple grid connection points corresponding to multiple off-grid electric fields respectively.

[0049] According to some embodiments, when constructing an island power grid, engineers design the parameters of each device of the island power grid (such as an off-grid power generation unit of an electric field, a step-up transformer of the power generation unit, a collection line, a step-up transformer of the collection station, a transmission line, a conventional power source, a reactive power compensation device, and a load, etc.) and the planned operation parameters of the island power grid. According to the planned operation parameters of the island power grid, a circuit model of the island power grid is established. According to the circuit model of the island power grid, a multi-port equivalent model of the island power grid can be obtained. According to one embodiment, the circuit model of the island power grid uses the Thevenin equivalent method to obtain the multi-port equivalent model of the island power grid.

[0050] According to some embodiments, based on the multi-port equivalent model of the island power grid, the impedance matrix and short-circuit capacity of the low-voltage side of the step-up transformer of the power generation unit, the impedance matrix and short-circuit capacity of the grid connection point, the active power of the power generation unit, and the active power of the off-grid power generation unit of the electric field can be obtained.

[0051] According to some embodiments, for an island power grid including four off-grid power generation units of electric fields, there are four grid connection points. Based on the multi-port equivalent model of the island power grid, a fourth-order grid connection point impedance matrix can be obtained. According to one embodiment, the fourth-order grid connection point impedance matrix is:

[0052]

[0053] According to one embodiment, each off-grid power generation unit of the electric field includes two power generation units. For the low-voltage side of the step-up transformer of the off-grid power generation unit of the electric field, based on the multi-port equivalent model of the island power grid, an eighth-order impedance matrix of the low-voltage side of the step-up transformer of the power generation unit can be obtained.

[0054] According to some embodiments, based on the impedance matrix and short-circuit capacity of the low-voltage side of the step-up transformer of the power generation unit, the impedance matrix and short-circuit capacity of the grid connection point, the active power of the power generation unit, and the active power of the off-grid power generation unit of the electric field, the multi-station short-circuit ratio of the low-voltage side of the step-up transformer of the power generation unit in multiple off-grid power generation units of the electric field and the multi-station short-circuit ratio of the grid connection point corresponding to each of the multiple off-grid power generation units of the electric field are calculated. According to one embodiment, on the multi-port equivalent model of the island power grid, the formula:

[0055]

[0056] Calculate the multi-station short-circuit ratio of the low-voltage side of the step-up transformers of the power generation units in multiple off-grid electric fields and the multi-station short-circuit ratio of the grid connection points corresponding to each of the multiple off-grid electric fields. Among them, MRSCRi represents the multi-station short-circuit ratio of the low-voltage side of the step-up transformer of the power generation unit in the ith off-grid electric field or represents the multi-station short-circuit ratio of the grid connection point corresponding to the ith off-grid electric field; Saci represents the short-circuit capacity of the low-voltage side of the step-up transformer of the power generation unit in the ith off-grid electric field or represents the short-circuit capacity of the grid connection point of the ith off-grid electric field; Prei and Prej represent the active power of the power generation units in the ith and jth off-grid wind farms or represent the active power of the ith and jth off-grid wind farms; Zeqii and Zeqij represent the self-impedance and mutual impedance of the low-voltage side of the step-up transformer of the power generation unit in the off-grid electric field or represent the self-impedance and mutual impedance of the grid connection point of the off-grid electric field.

[0057] According to one embodiment, for an island power grid including four off-grid electric fields, and each off-grid electric field includes two power generation units, according to the multi-station short-circuit ratio calculation formula, the multi-station short-circuit ratios of the low-voltage sides of the step-up transformers of the eight power generation units are obtained as MRSCR 1_1 、MRSCR 1_2 、MRSCR 2_1 、MRSCR 2_2 、MRSCR 3_1 、MRSCR 3_2 、MRSCR 4_1 and MRSCR 4_2 , and the multi-station short-circuit ratios of the grid connection points of the four off-grid electric fields are obtained as MRSCR1, MRSCR2, MRSCR3, and MRSCR4.

[0058] Step S201, in the case where there is a multi-station short-circuit ratio that does not meet the preset conditions among the multi-station short-circuit ratios of the low-voltage sides of the step-up transformers of the power generation units and the multi-station short-circuit ratios of the grid connection points, and none of the multiple off-grid electric fields are equipped with grid-forming energy storage, determine to configure grid-forming energy storage in the off-grid electric field corresponding to the minimum multi-station short-circuit ratio of the grid connection point.

[0059] According to some embodiments, in an island power grid, for multiple off-grid power generation fields, the multi-station short-circuit ratio at the low-voltage side of the step-up transformers of the power generation units in each off-grid power generation field and the multi-station short-circuit ratio at the grid connection points corresponding to each off-grid power generation field respectively have their own preset conditions. The conditions for the stable operation of the island power grid include that the multi-station short-circuit ratios at the low-voltage side of the step-up transformers of all power generation units in multiple off-grid power generation fields and the multi-station short-circuit ratios at the grid connection points corresponding to each off-grid power generation field respectively meet their own preset conditions. According to one embodiment, the preset conditions can be determined by technical personnel themselves, or can refer to the provisions in Section 6.12.3 of the national standard GB / T 40581-2021 "Power System Safety and Stability Calculation Code": For the case of multiple new energy stations accessing the AC system, the multi-station short-circuit ratio at the low-voltage side of the step-up transformer of the new energy power generation unit should not be less than 1.5, and the multi-station short-circuit ratio at the grid connection point of the new energy should not be less than 2.0 and preferably greater than 3.0.

[0060] According to some embodiments, if there are multi-station short-circuit ratios that do not meet the preset conditions among the multi-station short-circuit ratios at the low-voltage side of the step-up transformers of the power generation units in multiple off-grid power generation fields and the multi-station short-circuit ratios at the grid connection points corresponding to each off-grid power generation field, in order to ensure the stable operation of the island power grid, grid-forming energy storage needs to be configured in multiple off-grid power generation fields. In principle, grid-forming energy storage has the ability to improve the multi-station short-circuit ratio of off-grid power generation fields.

[0061] According to some embodiments, sort the multi-station short-circuit ratios at the grid connection points corresponding to each off-grid power generation field, determine the off-grid power generation field with the smallest multi-station short-circuit ratio at the grid connection point, and configure grid-forming energy storage in the low-voltage bus of the collection station of the off-grid power generation field corresponding to the smallest multi-station short-circuit ratio at the grid connection point. So that the multi-station short-circuit ratios at the low-voltage side of the step-up transformers of all power generation units in multiple off-grid power generation fields and the multi-station short-circuit ratios at the grid connection points corresponding to each off-grid power generation field respectively meet their own preset conditions, ensuring the stable operation of the island power grid. Configuring grid-forming energy storage in the off-grid power generation field corresponding to the smallest multi-station short-circuit ratio at the grid connection point can make the effect of improving the multi-station short-circuit ratio of the off-grid power generation field the most obvious, and at the same time can also give priority to solving the problem of the off-grid power generation field with the most serious non-compliance of the multi-station short-circuit ratio with the preset conditions.

[0062] According to some embodiments, when configuring grid-forming energy storage in the off-grid power generation field corresponding to the smallest multi-station short-circuit ratio at the grid connection point, first determine the capacity range of the configured grid-forming energy storage, and the capacity range includes multiple preset capacities. According to one embodiment, the form of the capacity range of grid-forming energy storage can include: the form of combining the upper and lower limits of the capacity with the capacity growth step size. For example, the capacity range ∈[S N_GFM_MIN ,S N_GFM_MAX , increasing in step size ΔS N_GFM ; the form of a set of capacity ranges of specific values. For example, the capacity range ∈{S N_GFM_1 ,S N_GFM_2 ,……,S N_GFM_N}}。

[0063] According to some embodiments, start selecting from the minimum preset capacity within the capacity range as the capacity of the configured grid-forming energy storage, and configure the grid-forming energy storage corresponding to the selected preset capacity in the off-grid power plant with the minimum multi-station short-circuit ratio at the connection point. For each selected preset capacity, equivalent the grid-forming energy storage corresponding to this preset capacity into the form of an ideal voltage source in series with an impedance and connect it to the island power grid circuit model, and calculate the multi-station short-circuit ratios at the low-voltage sides of the step-up transformers of the generating units in multiple off-grid power plants and the multi-station short-circuit ratios at the connection points corresponding to multiple off-grid power plants respectively, until the selected preset capacity reaches the maximum preset capacity, or the multi-station short-circuit ratios at the low-voltage sides of the step-up transformers of all generating units in multiple off-grid power plants and the multi-station short-circuit ratios at the connection points corresponding to multiple off-grid power plants respectively meet their respective preset conditions. In this way, the selected capacity of the grid-forming energy storage can not only meet the needs of the stable operation of the off-grid power plant, but also take into account the construction and maintenance costs of the energy storage, providing a basis for the technical and economic considerations in the capacity configuration of the grid-forming energy storage for the off-grid power plant, and balancing the technical and economic considerations in the capacity configuration of the grid-forming energy storage for the off-grid power plant.

[0064] According to some embodiments, it is also possible to arbitrarily select a preset capacity from within the capacity range as the capacity of the configured grid-forming energy storage according to experience, and configure the grid-forming energy storage corresponding to the selected preset capacity in the off-grid power plant with the minimum multi-station short-circuit ratio at the connection point. Equivalent the grid-forming energy storage corresponding to this preset capacity into the form of an ideal voltage source in series with an impedance and connect it to the island power grid circuit model, and calculate the multi-station short-circuit ratios at the low-voltage sides of the step-up transformers of the generating units in multiple off-grid power plants and the multi-station short-circuit ratios at the connection points corresponding to multiple off-grid power plants respectively. Arbitrarily selecting a preset capacity from within the capacity range as the capacity of the configured grid-forming energy storage according to experience can save the time for determining the capacity of the grid-forming energy storage.

[0065] According to some embodiments, if the multi-station short-circuit ratios at the low-voltage sides of all generating units in multiple off-grid power plants and the multi-station short-circuit ratios at the connection points corresponding to multiple off-grid power plants calculated respectively meet their respective preset conditions, then no longer select the capacity of the grid-forming energy storage, and directly connect the grid-forming energy storage corresponding to the selected preset capacity to the low-voltage busbar of the corresponding off-grid power plant collection station.

[0066] According to some embodiments, if there are multi-station short-circuit ratios that do not meet the preset conditions among the multi-station short-circuit ratios at the low-voltage sides of the step-up transformers of the generating units in multiple off-grid power plants and the multi-station short-circuit ratios at the connection points corresponding to multiple off-grid power plants calculated, then use the next preset capacity within the capacity range of the grid-forming energy storage as the current preset capacity, where the next preset capacity is greater than the currently corresponding preset capacity.

[0067] According to some embodiments, the preset capacities within the capacity range are sorted from small to large, and the next selected preset capacity can be the adjacent preset capacity of the currently corresponding preset capacity within the capacity range. In this way, the configured grid-forming energy storage capacity can not only meet the needs of the stable operation of the off-grid power plant, but also take into account the energy storage construction and maintenance costs, providing a basis for the technical and economic considerations of the grid-forming energy storage capacity configuration of the off-grid power plant, and balancing the technical and economic considerations of the grid-forming energy storage capacity configuration of the off-grid power plant. It can also be to select the next preset capacity according to experience, which can save the time for determining the capacity of the grid-forming energy storage.

[0068] According to some embodiments, the grid-forming energy storage corresponding to the selected preset capacity is equivalent to the form of an ideal voltage source in series with an impedance and connected to the island power grid circuit model, and the multi-station short-circuit ratios of the low-voltage sides of the step-up transformers of the power generation units in multiple off-grid power plants and the multi-station short-circuit ratios of the corresponding grid connection points of multiple off-grid power plants are calculated again until the selected preset capacity reaches the maximum preset capacity, or the multi-station short-circuit ratios of the low-voltage sides of the step-up transformers of all power generation units in multiple off-grid power plants and the multi-station short-circuit ratios of the corresponding grid connection points of multiple off-grid power plants respectively meet their respective preset conditions.

[0069] Figure 3 is a flowchart of a method for configuring grid-forming energy storage in an island power grid according to another embodiment of the present application. Compared with Figure 2 Compared with Figure 3 Steps S301 to S302 of Figure 2 are the same as steps S201 to S202 of Figure 3 The difference is that the method shown in

[0070] further includes the following steps:

[0071] Step S303, when there is a multi-station short-circuit ratio that does not meet the preset condition among the multi-station short-circuit ratios of the low-voltage sides of the step-up transformers of the power generation units and the multi-station short-circuit ratios of the grid connection points, and there is grid-forming energy storage configured in multiple off-grid power plants, determine whether the preset capacity currently corresponding to the configured grid-forming energy storage reaches the maximum preset capacity.

[0072] Step S304, when it is determined that the preset capacity currently corresponding to the configured grid-forming energy storage does not reach the maximum preset capacity, determine the next preset capacity within the capacity range of the configured grid-forming energy storage as the current preset capacity, where the next preset capacity is greater than the currently corresponding preset capacity.

[0073] According to some embodiments, in the case where grid-forming energy storage is configured in multiple off-grid electric fields, if there is a multi-station short-circuit ratio that does not meet the preset conditions among the multi-station short-circuit ratios on the low-voltage side of the step-up transformers of the power generation units and the multi-station short-circuit ratios at the grid connection points, it is determined whether the preset capacity currently corresponding to the configured grid-forming energy storage reaches the maximum preset capacity. If the preset capacity currently corresponding to the configured grid-forming energy storage does not reach the maximum preset capacity, the next preset capacity within the capacity range of the grid-forming energy storage is taken as the current preset capacity, where the next preset capacity is greater than the currently corresponding preset capacity. And the grid-forming energy storage corresponding to the selected current preset capacity is configured in the off-grid electric field corresponding to the minimum multi-station short-circuit ratio at the grid connection point.

[0074] According to some embodiments, the preset capacities within the capacity range are sorted from small to large, and the next preset capacity selected can be the adjacent preset capacity to the currently corresponding preset capacity within the capacity range. In this way, the capacity of the selected grid-forming energy storage can not only meet the needs of the stable operation of the off-grid electric field, but also take into account the construction and maintenance costs of the energy storage, providing a basis for the technical and economic considerations of the grid-forming energy storage capacity configuration of the off-grid electric field, and balancing the technical and economic considerations of the grid-forming energy storage capacity configuration of the off-grid electric field. It can also be to select the next preset capacity according to experience, which can save the time for determining the capacity of the grid-forming energy storage.

[0075] According to some embodiments, the grid-forming energy storage corresponding to the current preset capacity is equivalent to the form of an ideal voltage source in series with an impedance and connected to the island power grid circuit model, and the multi-station short-circuit ratios on the low-voltage side of the step-up transformers of the power generation units in multiple off-grid electric fields and the multi-station short-circuit ratios at the grid connection points corresponding to the multiple off-grid electric fields are calculated until the selected preset capacity reaches the maximum preset capacity, or all the multi-station short-circuit ratios on the low-voltage side of the step-up transformers of the power generation units in the multiple off-grid electric fields and the multi-station short-circuit ratios at the grid connection points corresponding to the multiple off-grid electric fields respectively meet their respective preset conditions.

[0076] Figure 4 is a flowchart of a method for configuring grid-forming energy storage in an island power grid according to another embodiment of the present application. Compared with Figure 3 Compared, Figure 4 Steps S401 to S405 are the same as steps S301 to S305 of Figure 3 The difference is that Figure 4 The method shown also includes the following steps:

[0077] Step S406, in the case where it is determined that the preset capacity currently corresponding to the configured grid-forming energy storage reaches the maximum preset capacity, determine the off-grid electric field corresponding to the minimum multi-station short-circuit ratio at the grid connection point in the off-grid electric field where the grid-forming energy storage is not configured as the off-grid electric field to be configured with the grid-forming energy storage.

[0078] According to some embodiments, in the case where grid-forming energy storage is configured in multiple off-grid electric fields, there is a multi-station short-circuit ratio that does not meet the preset conditions among the low-voltage side multi-station short-circuit ratios of the step-up transformers of the power generation units and the multi-station short-circuit ratios of the connection points, and it is determined that the preset capacity currently corresponding to the configured grid-forming energy storage reaches the maximum preset capacity. At this time, the multi-station short-circuit ratios of the connection points corresponding to the off-grid electric fields without configured grid-forming energy storage are sorted, and the off-grid electric field corresponding to the minimum multi-station short-circuit ratio of the connection point is used as the off-grid electric field to be configured with grid-forming energy storage.

[0079] Step S407: Configure grid-forming energy storage for the off-grid electric field to be configured with grid-forming energy storage.

[0080] According to some embodiments, determine the capacity range of the configured grid-forming energy storage, start selecting from the minimum preset capacity within the capacity range as the capacity of the configured grid-forming energy storage, and configure the grid-forming energy storage in the off-grid electric field to be configured with grid-forming energy storage. Each time a preset capacity is selected, the corresponding grid-forming energy storage is equivalent to the form of an ideal voltage source in series with an impedance and connected to the island power grid circuit model, and calculate the low-voltage side multi-station short-circuit ratios of the step-up transformers of the power generation units in multiple off-grid electric fields and the multi-station short-circuit ratios of the connection points corresponding to each off-grid electric field until the selected preset capacity reaches the maximum preset capacity, or the low-voltage side multi-station short-circuit ratios of all the power generation unit step-up transformers in multiple off-grid electric fields and the multi-station short-circuit ratios of the connection points corresponding to each off-grid electric field respectively meet their respective preset conditions. In this way, the selected capacity of the grid-forming energy storage can not only meet the needs of the stable operation of the off-grid electric field, but also take into account the construction and maintenance costs of the energy storage, providing a basis for the technical and economic considerations of the grid-forming energy storage capacity configuration of the off-grid electric field, and balancing the technical and economic considerations of the grid-forming energy storage capacity configuration of the off-grid electric field.

[0081] According to some embodiments, it is also possible to arbitrarily select a preset capacity from within the capacity range as the capacity of the configured grid-forming energy storage according to experience, and configure the grid-forming energy storage in the off-grid electric field to be configured with grid-forming energy storage. The selected grid-forming energy storage is equivalent to the form of an ideal voltage source in series with an impedance and connected to the island power grid circuit model, and calculate the low-voltage side multi-station short-circuit ratios of the step-up transformers of the power generation units in multiple off-grid electric fields and the multi-station short-circuit ratios of the connection points corresponding to each off-grid electric field. This can save the time for selecting the capacity of the configured grid-forming energy storage. According to some embodiments, if the low-voltage side multi-station short-circuit ratios of all the power generation unit step-up transformers in the calculated multiple off-grid electric fields and the multi-station short-circuit ratios of the connection points corresponding to each off-grid electric field respectively meet their respective preset conditions, then the capacity of the grid-forming energy storage is no longer selected, and the selected grid-forming energy storage is directly connected to the low-voltage bus of the off-grid electric field collection station to be configured with grid-forming energy storage.

[0082] According to some embodiments, if there is a multi-station short-circuit ratio that does not meet the preset conditions among the multi-station short-circuit ratios of the low-voltage sides of the step-up transformers of the power generation units in multiple off-grid electric fields and the multi-station short-circuit ratios corresponding to the grid connection points of the multiple off-grid electric fields respectively, then the next preset capacity within the capacity range of the grid-forming energy storage is taken as the current preset capacity, where the next preset capacity is greater than the currently corresponding preset capacity.

[0083] According to some embodiments, the preset capacities within the capacity range are sorted from small to large, and the next preset capacity selected can be the adjacent preset capacity of the currently corresponding preset capacity within the capacity range. In this way, the selected grid-forming energy storage capacity can not only meet the needs of the stable operation of the off-grid electric field, but also take into account the energy storage construction and maintenance costs, providing a basis for the technical and economic considerations of the grid-forming energy storage capacity configuration of the off-grid electric field, and balancing the technical and economic considerations of the grid-forming energy storage capacity configuration of the off-grid electric field. It can also be to select the next preset capacity according to experience, which can save the time for determining the capacity of the grid-forming energy storage.

[0084] According to some embodiments, the selected grid-forming energy storage is equivalent to the form of an ideal voltage source in series with an impedance and connected to the island power grid circuit model, and the multi-station short-circuit ratios of the low-voltage sides of the step-up transformers of the power generation units in the multiple off-grid electric fields and the multi-station short-circuit ratios corresponding to the grid connection points of the multiple off-grid electric fields are calculated again until the selected preset capacity reaches the maximum preset capacity, or all the multi-station short-circuit ratios of the low-voltage sides of the step-up transformers of the power generation units in the multiple off-grid electric fields and the multi-station short-circuit ratios corresponding to the grid connection points of the multiple off-grid electric fields respectively meet their respective preset conditions. And the grid-forming energy storage corresponding to the selected preset capacity is configured in the off-grid electric field where the grid-forming energy storage is to be configured.

[0085] According to the second aspect of the present application, there is provided a device for configuring grid-forming energy storage in an island power grid. As Figure 5 shown, the device includes the following modules:

[0086] A multi-station short-circuit ratio acquisition module 501, configured to acquire the multi-station short-circuit ratios of the low-voltage sides of the step-up transformers of the power generation units in the multiple off-grid electric fields and the multi-station short-circuit ratios corresponding to the grid connection points of the multiple off-grid electric fields respectively.

[0087] According to some embodiments, obtaining the multi-station short-circuit ratio of the low-voltage side of the step-up transformer of the power generation units in multiple off-grid electric fields and the multi-station short-circuit ratio of the grid connection points corresponding to each of the multiple off-grid electric fields includes: obtaining the planned operation parameters of the island power grid; establishing a circuit model of the island power grid according to the planned operation parameters; obtaining a multi-port equivalent model of the island power grid according to the circuit model; obtaining the impedance matrix and short-circuit capacity of the low-voltage side of the step-up transformer of the power generation unit, the impedance matrix and short-circuit capacity of the grid connection point, the active power of the power generation unit, and the active power of the off-grid electric field according to the multi-port equivalent model; calculating the multi-station short-circuit ratio of the low-voltage side of the step-up transformer of the power generation units in multiple off-grid electric fields and the multi-station short-circuit ratio of the grid connection points corresponding to each of the multiple off-grid electric fields according to the impedance matrix and short-circuit capacity of the low-voltage side of the step-up transformer of the power generation unit, the impedance matrix and short-circuit capacity of the grid connection point, the active power of the power generation unit, and the active power of the off-grid electric field.

[0088] The grid-forming energy storage configuration module 502 is configured to determine to configure grid-forming energy storage in the off-grid electric field corresponding to the minimum multi-station short-circuit ratio of the grid connection point when there is a multi-station short-circuit ratio that does not meet the preset condition among the multi-station short-circuit ratio of the low-voltage side of the step-up transformer of the power generation unit and the multi-station short-circuit ratio of the grid connection point, and none of the multiple off-grid electric fields are configured with grid-forming energy storage.

[0089] According to some embodiments, determining to configure grid-forming energy storage in the off-grid electric field corresponding to the minimum multi-station short-circuit ratio of the grid connection point includes: determining the capacity range of the configured grid-forming energy storage, where the capacity range includes multiple preset capacities; selecting a preset capacity within the capacity range as the capacity of the configured grid-forming energy storage; and calculating the multi-station short-circuit ratio of the low-voltage side of the step-up transformer of the power generation units in multiple off-grid electric fields and the multi-station short-circuit ratio of the grid connection points corresponding to each of the multiple off-grid electric fields according to the selected preset capacity.

[0090] The preset capacity judgment module 503 judges whether the preset capacity currently corresponding to the configured grid-forming energy storage reaches the maximum preset capacity.

[0091] According to some embodiments, when there is a multi-station short-circuit ratio that does not meet the preset condition among the multi-station short-circuit ratio of the low-voltage side of the step-up transformer of the power generation unit and the multi-station short-circuit ratio of the grid connection point, and there is grid-forming energy storage configured in the multiple off-grid electric fields, it is judged whether the preset capacity currently corresponding to the configured grid-forming energy storage reaches the maximum preset capacity.

[0092] The preset capacity determination module 504, when determining that the preset capacity currently corresponding to the configured grid-forming energy storage does not reach the maximum preset capacity, determines the next preset capacity within the capacity range of the configured grid-forming energy storage as the current preset capacity, where the next preset capacity is greater than the currently corresponding preset capacity.

[0093] According to some embodiments, when it is determined that the currently corresponding preset capacity of the configured grid-building energy storage has reached the maximum preset capacity, the off-grid electric field corresponding to the minimum grid-connected point multi-station short-circuit ratio is determined in the off-grid electric field that is not configured with grid-building energy storage as the off-grid electric field to be configured with grid-building energy storage, and grid-building energy storage is configured for the off-grid electric field to be configured with grid-building energy storage.

[0094] The multi-station short-circuit ratio calculation module 505 calculates the multi-station short-circuit ratios of the step-up and low-voltage sides of the power generation units in the multiple off-grid electric fields and the multi-station short-circuit ratios of the grid connection points corresponding to the multiple off-grid electric fields according to the current preset capacity.

[0095] See also Figure 6 , Figure 6 The electronic device provided in the present application includes 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 2 , Figure 3 and Figure 4 The method and refinement scheme shown.

[0096] It should be understood that the above device embodiments are only illustrative, and the device disclosed in the present invention can also be implemented in other ways. For example, the division of units / modules described in the above 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.

[0097] In addition, unless otherwise specified, each functional unit / module in each embodiment of the present invention 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.

[0098] When the integrated unit / module is implemented in the form of hardware, the hardware can 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 can be any suitable hardware processor, such as CPU, GPU, FPGA, DSP, and ASIC, etc. Unless otherwise specified, the on-chip cache, off-chip memory, and memory can be any suitable 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.

[0099] When 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 invention, in essence, or the part that contributes to the prior art, or all or part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a memory and includes several instructions to enable a computer electronic device (which can be a personal computer, a server, or a network electronic device, etc.) to execute all or part of the steps of the methods described in various embodiments of this disclosure. And the aforementioned memory includes: USB flash drive, read-only memory (ROM), random access memory (RAM), mobile hard disk, magnetic disk, or optical disc, etc., all kinds of media that can store program codes.

[0100] The embodiments of this application also provide a non-transitory computer storage medium storing a computer program. When the computer program is executed by multiple processors, it enables the processors to execute the methods and refinement schemes as shown in Figure 2 , Figure 3 and Figure 4 and the refinement schemes.

[0101] According to the configuration method of grid-forming energy storage in an island power grid proposed in this application, by starting to configure grid-forming energy storage from an off-grid power plant corresponding to the short-circuit ratio of multiple power plants at the minimum grid connection point, the effect of improving the short-circuit ratio of multiple power plants in the off-grid power plant can be made the most obvious. At the same time, the problem of the off-grid power plant with the most serious non-compliance of the short-circuit ratio of multiple power plants with the preset conditions can be solved preferentially. By starting to select the grid-forming energy storage to be configured from the minimum capacity in the optional range of the grid-forming energy storage capacity, it can be achieved that the selected grid-forming energy storage capacity not only meets the needs of the stable operation of the off-grid power plant, but also takes into account the construction and maintenance costs of the energy storage, providing a basis for the technical and economic considerations of the grid-forming energy storage capacity configuration of the off-grid power plant. This method balances the technical and economic considerations of the grid-forming energy storage capacity configuration of the off-grid power plant, providing a new idea for the grid-forming energy storage capacity configuration of the off-grid power plant in the power grid.

[0102] The above has introduced the embodiments of the present application in detail. Specific examples are used in this article to elaborate on the principles and implementation manners of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application. At the same time, based on the idea of the present application, changes or deformations made by those skilled in the art in the specific implementation manners and application scopes of the present application all belong to the protection scope of the present application. In summary, the content of this specification should not be construed as a limitation to the present application.

Claims

1. A configuration method for network-forming energy storage in an island power grid, the island power grid including a plurality of off-grid power plants, characterized in that Including: Obtaining the multi-station short-circuit ratio of the low-voltage side of the step-up transformer of the power generation units in the multiple off-grid power fields and the multi-station short-circuit ratio of the grid connection points corresponding to the multiple off-grid power fields respectively; And When there is a multi-station short-circuit ratio that does not meet the preset conditions among the multi-station short-circuit ratio of the low-voltage side of the step-up transformer of the power generation units and the multi-station short-circuit ratio of the grid connection points, and none of the multiple off-grid power fields are equipped with network-forming energy storage, determining to configure network-forming energy storage in the off-grid power field corresponding to the minimum multi-station short-circuit ratio of the grid connection point.

2. The method according to claim 1, characterized in that, Further including: When there is a multi-station short-circuit ratio that does not meet the preset conditions among the multi-station short-circuit ratio of the low-voltage side of the step-up transformer of the power generation units and the multi-station short-circuit ratio of the grid connection points, and there is network-forming energy storage configured in the multiple off-grid power fields, determining whether the preset capacity currently corresponding to the configured network-forming energy storage reaches the maximum preset capacity; When it is determined that the preset capacity currently corresponding to the configured network-forming energy storage does not reach the maximum preset capacity, determining the next preset capacity within the capacity range of the configured network-forming energy storage as the current preset capacity, where the next preset capacity is greater than the currently corresponding preset capacity; And Calculating the multi-station short-circuit ratio of the low-voltage side of the step-up transformer of the power generation units in the multiple off-grid power fields and the multi-station short-circuit ratio of the grid connection points corresponding to the multiple off-grid power fields respectively according to the current preset capacity.

3. The method according to claim 2, wherein Further including: When it is determined that the preset capacity currently corresponding to the configured network-forming energy storage reaches the maximum preset capacity, determining the off-grid power field corresponding to the minimum multi-station short-circuit ratio of the grid connection point in the off-grid power fields without configured network-forming energy storage as the off-grid power field to be configured with network-forming energy storage; And Configuring network-forming energy storage for the off-grid power field to be configured with network-forming energy storage.

4. The method according to claim 1, wherein The obtaining the multi-station short-circuit ratio of the low-voltage side of the step-up transformer of the power generation units in the multiple off-grid power fields and the multi-station short-circuit ratio of the grid connection points corresponding to the multiple off-grid power fields respectively includes: Obtaining the planned operation parameters of the island power grid; Establishing a circuit model of the island power grid according to the planned operation parameters; and Obtaining the multi-station short-circuit ratio of the low-voltage side of the step-up transformer of the power generation units in the multiple off-grid power fields and the multi-station short-circuit ratio of the grid connection points corresponding to the multiple off-grid power fields respectively according to the circuit model.

5. The method according to claim 4, wherein According to the circuit model, obtaining the multi-station short-circuit ratio of the low-voltage side of the step-up transformer of the power generation units in the multiple off-grid power fields and the multi-station short-circuit ratio of the grid connection points corresponding to the multiple off-grid power fields respectively includes: Obtaining the multi-port equivalent model of the island power grid according to the circuit model; Obtaining the impedance matrix and short-circuit capacity of the low-voltage side of the step-up transformer of the power generation unit, the impedance matrix and short-circuit capacity of the grid connection point, the active power of the power generation unit, and the active power of the off-grid power field according to the multi-port equivalent model; and Calculate the multi-station short-circuit ratio of the low-voltage side of the step-up transformer of the power generation unit in the multiple off-grid power plants and the multi-station short-circuit ratio of the connection points corresponding to the multiple off-grid power plants according to the impedance matrix and short-circuit capacity of the low-voltage side of the step-up transformer of the power generation unit, the impedance matrix and short-circuit capacity of the connection point, the active power of the power generation unit, and the active power of the off-grid power plant.

6. The method according to claim 1, wherein The determining to configure the network-forming energy storage in the off-grid power plant corresponding to the minimum multi-station short-circuit ratio of the connection point includes: Determine the capacity range of the configured network-forming energy storage, where the capacity range includes multiple preset capacities; Select a preset capacity within the capacity range as the capacity of the configured network-forming energy storage; and Calculate the multi-station short-circuit ratio of the low-voltage side of the step-up transformer of the power generation unit in the multiple off-grid power plants and the multi-station short-circuit ratio of the connection points corresponding to the multiple off-grid power plants according to the selected preset capacity.

7. The method according to claim 3, wherein The configuring the network-forming energy storage for the off-grid power plant to which the network-forming energy storage to be configured belongs includes: Determine the capacity range of the configured network-forming energy storage, where the capacity range includes multiple preset capacities; Select a preset capacity within the capacity range as the capacity of the configured network-forming energy storage; and Calculate the multi-station short-circuit ratio of the low-voltage side of the step-up transformer of the power generation unit in the multiple off-grid power plants and the multi-station short-circuit ratio of the connection points corresponding to the multiple off-grid power plants according to the selected preset capacity.

8. A configuration device for network-forming energy storage in an island power grid, characterized in that, Includes: A multi-station short-circuit ratio acquisition module for acquiring the multi-station short-circuit ratio of the low-voltage side of the step-up transformer of the power generation unit in the multiple off-grid power plants and the multi-station short-circuit ratio of the connection points corresponding to the multiple off-grid power plants; And A network-forming energy storage configuration module for determining to configure the network-forming energy storage in the off-grid power plant corresponding to the minimum multi-station short-circuit ratio of the connection point when there is a multi-station short-circuit ratio that does not meet the preset conditions among the multi-station short-circuit ratio of the low-voltage side of the step-up transformer of the power generation unit and the multi-station short-circuit ratio of the connection point, and when the multiple off-grid power plants are not configured with network-forming energy storage.

9. An electronic device, characterized in that, Includes a memory and a processor, where a computer program is stored on the memory, and the processor implements the method according to any one of claims 1 to 7 when executing the computer program on the memory.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, and the computer program implements the method according to any one of claims 1 to 7 when executed by a processor.

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