Network construction type energy storage planning method and system for improving new energy grid-connected scale

Abstract

The invention discloses a network construction type energy storage planning method and system for improving a new energy grid-connected scale, and the method comprises the steps: generating a section according to new energy output, load power utilization, conventional unit output and corresponding frequency and voltage data, and carrying out the clustering of the section data, and obtaining a typical scene for the network construction type energy storage planning; constructing a new energy power system small interference model containing new energy and network-construction-type energy storage, and extracting a generalized short-circuit ratio index representing the active supporting capability of the network-construction-type energy storage on the voltage of the new energy power system; quantitatively representing the minimum demand of the new energy power system on the network construction type energy storage, and taking the minimum demand as a constraint condition of network construction type energy storage planning; constructing a network construction type energy storage planning model for improving the new energy grid-connected scale by taking the lowest planning cost as a target; and solving the model to obtain the capacity and site selection of the network construction type energy storage. According to the invention, the active supporting capability of the network-building type energy storage on the voltage and frequency of the system is fully considered, and the access capability of new energy can be improved on the basis of not newly adding a conventional power supply.

Description

Technical Field

[0001] The present invention belongs to the field of electric power technology, and in particular to a grid-connected energy storage planning method and system for improving the scale of new energy grid connection. Background Art

[0002] With the continuous development of new energy, the volatility and uncertainty of its output have caused increasingly prominent pressure on system operation. With the further development of new power systems, the output of conventional units has been restricted, and the system's peak-shaving, frequency regulation and voltage support capabilities have continued to decline, limiting the level of new energy access. It is urgent to tap new resources to support the system and support the development of new power systems.

[0003] In recent years, energy storage technology has developed rapidly. It can realize four-quadrant operation of active and reactive power through converters. It has strong power controllability and response speed of ms level. It can be used to improve the safety and stability of power system voltage, frequency and other issues. According to the converter control method, energy storage can be divided into grid-following energy storage and grid-building energy storage. Among them, grid-building energy storage has the characteristics of voltage source to the outside, can form active voltage support for the power grid, and is more suitable for high-proportion new energy power systems. At present, energy storage planning is mainly in peak load regulation and frequency regulation. For example, the capacity and address of energy storage are planned by using a two-layer planning model to improve the level of new energy consumption. Some scholars have proposed a robust optimization model for energy storage capacity configuration in response to the impact of severe weather. However, the above optimization model assumes energy storage as a PQ model, which cannot reflect the supporting role of energy storage on system voltage after a fault. If the voltage support role is considered, a large amount of transient simulation is required to determine the fault set, and the amount of calculation is very large. Summary of the invention

[0004] The purpose of the present invention is to provide a grid-connected energy storage planning method and system for improving the scale of new energy grid connection, fully considering the active support capability of grid-connected energy storage for system voltage and frequency, and improving the access capability of new energy without adding conventional power sources.

[0005] In order to achieve the above object, the solution of the present invention is:

[0006] A grid-connected energy storage planning method for increasing the scale of new energy grid connection includes:

[0007] Generate multiple sections based on renewable energy output, load power consumption, conventional unit output, and corresponding frequency and voltage data, and cluster the section data to obtain typical scenarios for grid-type energy storage planning;

[0008] Construct a small disturbance model of a new energy power system that includes new energy and grid-connected energy storage, and extract a generalized short-circuit ratio index that characterizes the ability of grid-connected energy storage to actively support the voltage of the new energy power system;

[0009] Based on the generalized short-circuit ratio index, the minimum demand of the new energy power system for grid-connected energy storage is quantitatively characterized as a constraint condition for grid-connected energy storage planning;

[0010] With the goal of minimizing planning costs, a grid-connected energy storage planning model is constructed to increase the scale of new energy grid connection;

[0011] The grid-type energy storage planning model is solved to obtain the capacity and site selection of the grid-type energy storage.

[0012] Among them, a small disturbance model of a new energy power system including new energy and grid-connected energy storage is constructed, including:

[0013] The small disturbance model of the new energy power system is as follows:

[0014] ΔI=Y eq ΔV

[0015] Among them, ΔV and ΔI are the voltage and current changes after the system is disturbed, and Y eq is the equivalent admittance matrix of the new energy power system, and we have:

[0016] Y eq =Y NE (s)+Y GRID (s)+Y ES (s)

[0017] Among them, Y ES (s) is the transfer function matrix of the network energy storage admittance, Y NE (s) is the admittance transfer function matrix of the new energy station, Y GRID (s) is the admittance transfer function matrix on the AC grid side.

[0018] Among them, the grid-type energy storage admittance transfer function matrix Y ES The expression of (s) is,

[0019]

[0020] Among them, S ESi is the rated capacity of the grid-type energy storage, Y ES (s) is the admittance transfer function matrix of the grid-type energy storage; ΔU di ,ΔU qi are the d-axis component and q-axis component of the voltage disturbance at node i, respectively; ΔI di ,ΔI qi The d-axis component and q-axis component of the current variation are injected into node i respectively.

[0021] Among them, the new energy station admittance transfer function matrix Y NE The expression of (s) is,

[0022]

[0023] Among them, S BNE is the capacity ratio matrix, Y NS (s) is the admittance transfer function of a single wind turbine.

[0024] Among them, the AC grid side admittance transfer function matrix Y GRID The expression of (s) is,

[0025]

[0026] Among them, ΔI GRID is the injected current of the AC network part, ΔV GRID is the bus voltage; w0 is the standard angular frequency, s is the frequency domain variable; B is the node admittance matrix, represents the Kronecker product.

[0027] Among them, the generalized short-circuit ratio index that characterizes the active support capability of grid-connected energy storage for the voltage of new energy power systems is extracted, including:

[0028] The node admittance matrix B is corrected to:

[0029] B i ' i =B ii +B eq

[0030] In the formula, B ii ,B i ' i are the self-admittance of node i before and after it is connected to the grid-forming energy storage; B eq is the equivalent admittance of the grid-type energy storage;

[0031] The characteristic equation detY eq =0 and perform equivalent transformation to obtain,

[0032]

[0033] in, I n is the n-order unit matrix; j For the matrix The jth eigenvalue of n , j = 1,…,n; B n ′ is the modified admittance matrix;

[0034] The minimum eigenvalue of the matrix is ​​defined as the generalized short-circuit ratio gSCR,

[0035]

[0036] in, λ (·) is the smallest eigenvalue of the matrix.

[0037] Among them, based on the generalized short-circuit ratio index, the minimum demand of the new energy power system for grid-type energy storage is quantitatively characterized as a constraint condition for grid-type energy storage planning, including:

[0038] Assume that the power fed into the AC grid by the grid-connected energy storage is P ES ,have,

[0039]

[0040] Among them, V o and V g are the export voltage of the grid-type energy storage and the voltage of the AC grid respectively; δ is the power angle; Y eq is the equivalent admittance matrix of the new energy power system;

[0041] The minimum generalized short-circuit ratio of the new energy power system is,

[0042] SCR min = λ ((V o V g ) -1 P ES (sinδ) -1 n )

[0043] in, λ (·) is the smallest eigenvalue of the matrix.

[0044] Among them, with the goal of minimizing planning costs, a grid-connected energy storage planning model is constructed to increase the scale of new energy grid connection, including:

[0045] The target of the grid-type energy storage planning model is the economic cost C ESS Minimum, including initial investment cost and operation and maintenance costs

[0046] The constraints include that the generalized short circuit ratio satisfies the minimum short circuit ratio requirement.

[0047] The grid-type energy storage planning model is solved to obtain the capacity and site selection of the grid-type energy storage, including:

[0048] The nonlinear terms in the objective function and constraints of the grid-type energy storage planning model are discretized using the binary expansion method to simplify the model and then solve it.

[0049] A grid-connected energy storage planning system for increasing the scale of new energy grid connection, comprising:

[0050] The typical scenario construction module is configured to generate multiple sections based on the output of new energy, load power consumption, output of conventional units, and corresponding frequency and voltage data, and cluster the section data to obtain typical scenarios for grid-type energy storage planning;

[0051] A generalized short-circuit ratio index acquisition module is configured to construct a small disturbance model of a new energy power system including new energy and grid-type energy storage, and extract a generalized short-circuit ratio index that characterizes the ability of the grid-type energy storage to actively support the voltage of the new energy power system;

[0052] A constraint condition acquisition module is configured to quantitatively characterize the minimum demand of the new energy power system for grid-forming energy storage based on the generalized short-circuit ratio index as a constraint condition for grid-forming energy storage planning;

[0053] A grid-type energy storage planning model building module is configured to build a grid-type energy storage planning model that increases the scale of new energy grid connection with the goal of minimizing planning costs; and

[0054] The model solving module is configured to solve the grid-type energy storage planning model to obtain the capacity and site selection of the grid-type energy storage.

[0055] After adopting the above scheme, the present invention fully considers the active support capability of the grid-type energy storage for the system voltage and frequency, determines the capacity and site selection of the grid-type energy storage, so as to ensure that the system short-circuit ratio operates at a safe level, and can improve the access capability of new energy without adding conventional power sources. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0057] The technical solutions and beneficial effects of the present invention will be described in detail below with reference to the accompanying drawings.

[0058] like Figure 1 As shown, the present invention provides a grid-connected energy storage planning method for improving the scale of new energy grid connection, comprising the following steps:

[0059] S1. Generate multiple sections based on historical data such as renewable energy output, load power consumption, conventional unit output, and corresponding frequency and voltage, and use clustering algorithms such as k-mcam to generate typical planning scenarios;

[0060] The S1 comprises the following steps:

[0061] S101, generating a plurality of sections according to historical data such as new energy output, load power consumption, conventional unit output, and corresponding frequency and voltage, wherein the types of sections include but are not limited to new energy output, new energy output, peak load, and random combination of valley load.

[0062] S102, clustering algorithms such as k-means are used to cluster the above-mentioned section data, reduce the scale of the scenario, and make predictions considering future load growth and new energy development trends to form typical scenarios for grid-type energy storage planning, so that the planning results can cope with various types of results.

[0063] S2. Construct a generalized short-circuit ratio index to characterize the ability of grid-connected energy storage to actively support the voltage of new energy power systems;

[0064] The S2 comprises the following steps:

[0065] S201, construct a small disturbance model of a new energy power system including new energy and grid-connected energy storage.

[0066] The small signal model of this system mainly reflects the relationship between current and voltage after the new energy power system is disturbed, as follows:

[0067] ΔI=Y eq ΔV (1)

[0068] In the formula, ΔV and ΔI are the voltage and current changes of the new energy power system after the system is disturbed, and Y eq It is the equivalent admittance matrix of the new energy power system, which mainly includes three parts: the grid-type energy storage admittance transfer function matrix Y ES (s), new energy admittance transfer function matrix Y NE (s) and the admittance transfer function matrix Y of the AC power grid itself GRID (s).

[0069] (1) Network-type energy storage admittance transfer function matrix Y ES (s)

[0070] The small disturbance model of grid-type energy storage is:

[0071]

[0072] Where: S ESi is the rated capacity of the grid-type energy storage, Y ES (s) is the admittance transfer function matrix of the grid-type energy storage; ΔU di ,ΔU qi are the d-axis component and q-axis component of the voltage disturbance at node i, respectively; ΔI di ,ΔI qiThe d-axis component and q-axis component of the current variation injected into node i are respectively; its elements can be expressed as:

[0073]

[0074] Where:

[0075]

[0076] Where: K ip , K ii K is the inner loop PI control parameter of the grid-type energy storage current; pp , K pi is the PI control parameter of the outer loop of the grid-type energy storage power; T PQ is the filter time constant; I0 ​​and U0 are the initial values ​​of the output current and voltage of the grid-type energy storage; L f It is a filter inductor for network-type energy storage.

[0077] (2) New energy station admittance transfer function matrix Y NE (s)

[0078] The admittance transfer function matrix of the new energy station is:

[0079]

[0080] In the formula, S BNE is the capacity ratio matrix, Y NS (s) is the admittance transfer function of a single wind turbine.

[0081] (3) AC grid side admittance transfer function matrix Y GRID (s)

[0082] Y GRID (s) represents the injected current ΔI of the AC network part GRID and bus voltage ΔV GRID The relationship between them is:

[0083]

[0084]

[0085] Where, w0 is the standard angular frequency, w0 = 100πrad / s; B is the node admittance matrix, represents the Kronecker product, and s represents the frequency domain variable.

[0086] (4) Equivalent admittance matrix of new energy power system

[0087] Combining the above three types of admittance matrices, the equivalent admittance matrix of the new energy power system can be obtained as follows:

[0088] Y eq =Y NE (s)+Y GRID (s)+Y ES (s) (7)

[0089] S202: Based on the above-mentioned small disturbance model, a generalized short-circuit ratio index is extracted to characterize the ability of the grid-connected energy storage to actively support the voltage of the new energy power system.

[0090] The small disturbance stability of the renewable energy power system is determined by the dominant eigenvalue shown in the following equation:

[0091] Y eq =0 (8)

[0092] In the small disturbance stability analysis, the voltage source busbar dynamics is equal to 0, which is equivalent to grounding. Therefore, the node admittance matrix B in equation (6) is corrected to:

[0093] B i ' i =B ii +B eq (9)

[0094] In the formula, B ii ,B i ' i B is the self-admittance of node i before and after it is connected to the grid-connected energy storage; eq is the equivalent admittance of the grid-type energy storage.

[0095] Based on the correction of network admittance, the characteristic equation in equation (8) is equivalently transformed into:

[0096]

[0097] In the formula, I n is the n-order unit matrix; j For the matrix The jth eigenvalue (0<λ1<λ2≤…≤λ n , j=1,…,n); B n ′ is the modified admittance matrix.

[0098] The stability of the system depends on the minimum eigenvalue λ1 of the matrix, which is a key parameter to quantify the strength of the system and can be defined as the generalized Short-Circuit Ratio (gSCR), which is

[0099]

[0100] In the formula, λ (·) is the smallest eigenvalue of the matrix.

[0101] S3. Based on the generalized short-circuit ratio index, the minimum demand of the new energy power system for grid-connected energy storage is quantitatively characterized as a constraint condition for grid-connected energy storage planning;

[0102] The S3 comprises the following steps:

[0103] Assume that the power fed into the AC grid by the grid-connected energy storage is P ES ,but:

[0104]

[0105] Where V o and V g are the export voltage of the grid-connected energy storage and the voltage of the AC grid respectively; δ is the power angle.

[0106] According to the definition of generalized short-circuit ratio, the minimum generalized short-circuit ratio of the new energy power system is:

[0107] SCR min = λ ((V o V g ) -1 P ES (sinδ) -1 n ) (13)

[0108] S4. With the goal of minimizing planning costs, a grid-connected energy storage planning model is constructed to increase the scale of new energy grid connection;

[0109] The S4 comprises the following steps:

[0110] (1) Objective function

[0111] The goal of grid-type energy storage planning is to achieve economic cost C ESS Minimum, including initial investment cost and operation and maintenance costs As shown in the following formula.

[0112]

[0113] In the formula, β ESS is the initial investment ratio coefficient, and its expression is:

[0114]

[0115] In the formula, r ESS For return on investment.

[0116] Operation and maintenance costs Including the operation and maintenance costs of energy storage and wind curtailment compensation costs According to the typical scenarios divided in step S1, the operating cost in each typical scenario can be calculated, and then the weighted sum is obtained.

[0117]

[0118] In the formula, μ s The probability of generating scene s; Ω s is the set of running scenarios; T is the planning time scale; N G is the number of units; is the active power of the unit i at the node t in scenario s; c R is the reserve coefficient; is the spare capacity of unit i at node t in scenario s; N W is the number of fans; is the wind curtailment rate of wind turbine group i at time t in scenario s; is the active power of wind turbine at node i at time t in scenario s.

[0119] (2) Constraints

[0120] Constraints include energy storage power upper and lower limits, generator output upper and lower limits, power flow balance constraints, energy storage operation constraints and other conventional constraints, which will not be repeated here. However, the grid-type energy storage planning should consider the generalized short-circuit ratio to meet the minimum short-circuit ratio requirements. As follows:

[0121] gSCR ≥ gSCR min (17)

[0122] S5. Linearize the model, simplify the model and solve it to obtain the capacity and site selection of the grid-type energy storage.

[0123] The S5 comprises the following steps:

[0124] The objective function and constraints in the equation contain nonlinear terms, and the nonlinear terms are discretized using the binary expansion method. The formula is as follows:

[0125]

[0126] In the formula, y l is the minimum value, y m is the maximum value, z k (k=1,…,K) is a binary variable with a step size accuracy of Δy=(y m -y l ) / 2 K , K is the number of segments in the linearization process.

[0127] Formula (18) is used to simplify the nonlinear terms in the model, which makes it easier to solve.

[0128] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes. The schemes in the embodiments of the present invention may be implemented in various computer languages, for example, object-oriented programming language Java and literal scripting language JavaScript, etc.

[0129] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0130] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0131] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0132] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0133] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A grid-connected energy storage planning method for increasing the scale of new energy grid connection, characterized by: include, Generate sections based on renewable energy output, load power consumption, conventional unit output, and corresponding frequency and voltage data, and cluster the section data to obtain typical scenarios for grid-type energy storage planning; Construct a small disturbance model of a new energy power system that includes new energy and grid-connected energy storage, and extract a generalized short-circuit ratio index that characterizes the ability of grid-connected energy storage to actively support the voltage of the new energy power system; Based on the generalized short-circuit ratio index, the minimum demand of the new energy power system for grid-connected energy storage is quantitatively characterized as a constraint condition for grid-connected energy storage planning; With the goal of minimizing planning costs, a grid-connected energy storage planning model is constructed to increase the scale of new energy grid connection; The grid-type energy storage planning model is solved to obtain the capacity and site selection of the grid-type energy storage.

2. The method according to claim 1, characterized in that: Construct a small disturbance model of a new energy power system including new energy and grid-connected energy storage, including: The small disturbance model of the new energy power system is as follows: ΔI=Y eq ΔV Among them, ΔV and ΔI are the voltage and current changes after the system is disturbed, and Y eq is the equivalent admittance matrix of the new energy power system, and we have: AND eq =And NE (s)+Y GRID (s)+Y ES (s) Among them, Y ES (s) is the transfer function matrix of the network energy storage admittance, Y NE (s) is the admittance transfer function matrix of the new energy station, Y GRID (s) is the admittance transfer function matrix on the AC grid side.

3. The method according to claim 2, characterized in that: The network type energy storage admittance transfer function matrix Y ES The expression of (s) is, Among them, S ESi is the rated capacity of the grid-type energy storage, Y ES (s) is the admittance transfer function matrix of the grid-type energy storage; ΔU di ,ΔU qi are the d-axis component and q-axis component of the voltage disturbance at node i respectively; ΔI di ,ΔI qi The d-axis component and q-axis component of the current variation are injected into node i respectively.

4. The method according to claim 2, characterized in that: The new energy station admittance transfer function matrix Y NE The expression of (s) is, Among them, S BNE is the capacity ratio matrix, Y NS (s) is the admittance transfer function of a single wind turbine.

5. The method according to claim 2, characterized in that: The AC grid side admittance transfer function matrix Y GRID The expression of (s) is, Among them, ΔI GRID is the injected current of the AC network part, ΔV GRID is the bus voltage; w0 is the standard angular frequency, s is the frequency domain variable; B is the node admittance matrix, represents the Kronecker product.

6. The method according to claim 5, characterized in that: Extract the generalized short-circuit ratio index that characterizes the active voltage support capability of grid-connected energy storage for new energy power systems, including: The node admittance matrix B is corrected to: B i ′ i =B ii +B eq In the formula, B ii ,B i ' i are the self-admittance of node i before and after it is connected to the grid-forming energy storage; B eq is the equivalent admittance of the grid-type energy storage; The characteristic equation detY eq =0 and perform equivalent transformation to obtain, in, I n is the n-order unit matrix; j For the matrix The jth eigenvalue of n , j = 1,…,n; B n ′ is the modified admittance matrix; The minimum eigenvalue of the matrix is ​​defined as the generalized short-circuit ratio gSCR, Where λ(·) is the minimum eigenvalue of the matrix.

7. The method according to claim 1, characterized in that: Based on the generalized short-circuit ratio index, the minimum demand of the new energy power system for grid-connected energy storage is quantitatively characterized as a constraint condition for grid-connected energy storage planning, including: Assume that the power fed into the AC grid by the grid-connected energy storage is P ES ,have, Among them, V o and V g are the export voltage of the grid-type energy storage and the voltage of the AC grid respectively; δ is the power angle; Y eq is the equivalent admittance matrix of the new energy power system; The minimum generalized short-circuit ratio of the new energy power system is, gSCR min = λ ((V o V g ) -1 P ES (sinδ) -1 n ) in, λ (·) is the smallest eigenvalue of the matrix.

8. The method according to claim 1, characterized in that: With the goal of minimizing planning costs, a grid-connected energy storage planning model is constructed to increase the scale of new energy grid connection, including: The target of the grid-type energy storage planning model is the economic cost C ESS Minimum, including initial investment cost and operation and maintenance costs The constraints include that the generalized short circuit ratio satisfies the minimum short circuit ratio requirement.

9. The method according to claim 1, characterized in that: The grid-type energy storage planning model is solved to obtain the capacity and site selection of the grid-type energy storage, including: The nonlinear terms in the objective function and constraints of the grid-type energy storage planning model are discretized using the binary expansion method to simplify the model and then solve it.

10. A grid-connected energy storage planning system for increasing the scale of new energy grid connection, characterized in that: include, The typical scenario construction module is configured to generate multiple sections based on the output of new energy, load power consumption, output of conventional units, and corresponding frequency and voltage data, and cluster the section data to obtain typical scenarios for grid-type energy storage planning; A generalized short-circuit ratio index acquisition module is configured to construct a small-disturbance model of a new energy power system including new energy and grid-type energy storage, and extract a generalized short-circuit ratio index that characterizes the ability of the grid-type energy storage to actively support the voltage of the new energy power system; A constraint condition acquisition module is configured to quantitatively characterize the minimum demand of the new energy power system for grid-forming energy storage based on the generalized short-circuit ratio index as a constraint condition for grid-forming energy storage planning; A grid-type energy storage planning model building module is configured to build a grid-type energy storage planning model that increases the scale of new energy grid connection with the goal of minimizing planning costs; and The model solving module is configured to solve the grid-type energy storage planning model to obtain the capacity and site selection of the grid-type energy storage.

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