Networking type energy storage site selection method for improving stability and economical efficiency of alternating-current and direct-current hybrid system

Abstract

The invention discloses a networking type energy storage site selection method for improving stability and economical efficiency of an alternating current and direct current hybrid system. The method comprises the steps that nodes in the alternating current and direct current hybrid system serve as alternative addresses for additionally installing networking type energy storage; and screening nodes according to the system stability after the nodes are connected with the network-building energy storage, calculating the investment cost of adding the network-building energy storage to each node in the stable node set, and selecting the node with the lowest investment cost as the optimal access position of the network-building energy storage. According to the method, the minimum generalized short-circuit ratio is used as a stability criterion, and all stable node sets meeting stability constraints are systematically screened out; further calculating the investment cost required when each stable node accesses the network-building energy storage, and finally determining the node with the lowest investment cost as the optimal access node. According to the method, the stability of the alternating-current and direct-current hybrid system can be ensured, the minimum investment of network construction type energy storage is realized, and the planning efficiency and the economic benefit of the network construction type energy storage in a new energy high-permeability power grid can be improved.

Description

Technical Field

[0001] This invention relates to the field of power system analysis technology for new energy generating units, and in particular to a grid-type energy storage site selection method and system. Background Technology

[0002] AC / DC hybrid power grids are crucial infrastructure for advancing the energy revolution and ensuring the safe and efficient transmission and consumption of large-scale renewable energy in the new era. With the high proportion of grid-connected renewable energy units and the gradual retirement of traditional units, system inertia is continuously decreasing, and stability issues such as sub- / supersynchronous oscillations and broadband oscillations are becoming increasingly prominent, seriously threatening the safe operation of the power grid. Grid-based energy storage systems, with their ability to actively provide damping and inertia support, are considered one of the effective means to improve system stability. However, in practical planning, how to scientifically determine the optimal access location for grid-based energy storage to meet system stability requirements with minimal investment cost remains a key technical challenge that urgently needs to be addressed.

[0003] Existing technologies primarily rely on empirical site selection methods based on local short-circuit ratios. These methods involve configuring a certain capacity of grid-connected energy storage at each candidate node and then performing time-domain simulations or eigenvalue analysis to verify whether stability requirements are met. These methods suffer from high computational complexity, limited evaluation nodes, and difficulty in achieving global optimization. Furthermore, they fail to adequately consider the interactive effects of large-scale grid-connected converters on the grid's equivalent admittance, leading to conservative site selection results and high investment costs. While some studies have proposed fast stability criteria based on the generalized short-circuit ratio, most focus only on a single dimension of stability, failing to incorporate construction and maintenance costs into the optimization framework. This makes it difficult to simultaneously optimize system stability and economics, and to accurately guide the optimal deployment of grid-connected energy storage in complex AC / DC hybrid power grids. In practical engineering scenarios with high proportions of renewable energy integration, minimizing investment costs while ensuring that stability indicators such as the generalized short-circuit ratio meet requirements has become a key bottleneck restricting the large-scale engineering application of grid-connected energy storage. Summary of the Invention

[0004] In view of this, in order to overcome the shortcomings of the prior art, the present invention provides a method for site selection of grid-type energy storage to improve the stability and economy of AC / DC hybrid systems, so as to solve the technical problems of system oscillation, reduced stability and high investment costs caused by improper selection of grid-type energy storage access locations.

[0005] The present invention provides a method for site selection of grid-type energy storage to improve the stability and economy of AC / DC hybrid systems, comprising:

[0006] 1) Use nodes in AC / DC hybrid systems as alternative locations for installing grid-type energy storage;

[0007] 2) Select nodes based on system stability after connecting nodes in a grid-type energy storage system, including:

[0008] Calculate the minimum generalized short-circuit ratio of the AC / DC hybrid system before adding grid-type energy storage, and the actual generalized short-circuit ratio of the system after adding grid-type energy storage at a certain node. If the actual generalized short-circuit ratio is greater than the minimum generalized short-circuit ratio, the AC / DC hybrid system meets the system stability requirements after adding grid-type energy storage at that node, and the node is included in the set of stable nodes.

[0009] 3) Calculate the investment cost of installing grid-type energy storage on each node in the stable node set, and select the node with the lowest investment cost as the optimal access location for grid-type energy storage.

[0010] Furthermore, in step 2), the actual generalized short-circuit ratio of the system after adding a grid-type energy storage at a certain node is calculated. The calculation formula is as follows:

[0011]

[0012] in, It is the Thevenin equivalent admittance matrix of the system after adding grid-type energy storage at the nodes. It is the inverse of the characteristic matrix of the grid-type converter in the AC / DC hybrid system.

[0013] Furthermore, in step 2), the minimum generalized short-circuit ratio k of the AC / DC hybrid system before the installation of grid-type energy storage is calculated. SCRMin The calculation formula is as follows:

[0014]

[0015]

[0016] Where arg(·) is the root operator of the equation. It is the admittance transfer matrix of the grid converter in an AC / DC hybrid system. It is the actual generalized short-circuit ratio of the AC / DC hybrid system before the addition of grid-type energy storage. ω0 is the Thevenin equivalent admittance matrix of the system before the installation of grid-type energy storage, ω0 is the system synchronization frequency, and s is the Laplace operator.

[0017] Furthermore, the formula for calculating the investment cost W of installing grid-type energy storage on each node in the stable node set in step 3) is as follows:

[0018]

[0019] Among them, W B The construction cost required to install grid-type energy storage at a node in a stable node cluster, W O The operation and maintenance cost required after installing a grid-type energy storage system on a node in a stable node set.

[0020] Furthermore, the construction cost W B The calculation formula is as follows:

[0021]

[0022] Among them, C VSM The unit investment cost of grid-type energy storage; x is the location decision variable, d is the line distance from the grid-type energy storage to the node, and C is the unit investment cost of grid-type energy storage. line C represents the unit investment cost of transmission lines. f For fixed costs, PR is the capital recovery factor; the formula for calculating PR is as follows:

[0023]

[0024] Where r is the discount rate and Y is the planning period.

[0025] Furthermore, the aforementioned operation and maintenance cost W O The calculation formula is as follows:

[0026]

[0027] Where u is the ratio coefficient of operation and maintenance costs.

[0028] Furthermore, the method for site selection of grid-type energy storage to improve the stability and economy of AC / DC hybrid systems, as described in step 2), also includes a matrix for calculating the actual generalized short-circuit ratio of the AC / DC hybrid system before the installation of grid-type energy storage. Find the corresponding matrix The eigenvectors of the eigenvalues ​​are used to calculate the participation factor p of adding grid-type energy storage to node j in the AC / DC hybrid system. The formula for calculating the participation factor p is as follows:

[0029]

[0030] Among them, u j For matrix The j-th element in the left eigenvector corresponding to the eigenvalue, v j For matrix The j-th element in the right eigenvector corresponding to the eigenvalue;

[0031] The nodes are sorted from largest to smallest based on the value of the participation factor. Then, the actual generalized short-circuit ratio of the system after adding energy storage is calculated in order for each node. Finally, the nodes that meet the system stability requirements after adding grid-type energy storage are included in the set of stable nodes.

[0032] The beneficial effects of this invention are:

[0033] This invention provides a grid-based energy storage site selection method to improve the stability and economy of AC / DC hybrid systems, using the minimum generalized short-circuit ratio k. SCRMin As a stability criterion, a systematic set of all stable nodes satisfying stability constraints is selected. Further, the investment cost required to connect each stable node to grid-based energy storage is calculated, and candidate nodes are ranked by economic efficiency. Finally, the node with the lowest investment cost is determined as the optimal connection node. This method can minimize the investment in grid-based energy storage while ensuring the stability of the AC / DC hybrid system. The calculation process is structured and the computational load is controllable, improving the planning efficiency and economic benefits of grid-based energy storage in grids with high penetration rates of new energy sources. Attached Figure Description

[0034] Figure 1 Flowchart of a grid-type energy storage site selection method to improve the stability and economy of AC / DC hybrid systems. Detailed Implementation

[0035] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0036] The grid-type energy storage site selection method for improving the stability and economy of AC / DC hybrid systems in this embodiment includes:

[0037] 1) Use nodes in the AC / DC hybrid system as alternative locations for installing grid-type energy storage.

[0038] 2) Select nodes based on system stability after connecting nodes in a grid-type energy storage system, including:

[0039] Calculate the minimum generalized short-circuit ratio of the AC / DC hybrid system before the installation of grid-type energy storage, and the actual generalized short-circuit ratio of the system after the installation of grid-type energy storage at a certain node.

[0040] In step 2), the actual generalized short-circuit ratio of the system after connecting the grid-type energy storage at a certain node c is calculated. The calculation formula is as follows:

[0041]

[0042] in, It is the Thevenin equivalent admittance matrix of the system after adding a grid-type energy storage at node c. It is the inverse of the characteristic matrix of the grid-type converter in the AC / DC hybrid system.

[0043] In step 2), the minimum generalized short-circuit ratio k of the AC / DC hybrid system before the installation of grid-type energy storage is calculated. SCRMin The calculation formula is as follows:

[0044]

[0045]

[0046] Where arg(·) is the root operator of the equation. It is the admittance transfer matrix of the grid converter in an AC / DC hybrid system. It is the actual generalized short-circuit ratio of the AC / DC hybrid system before the addition of grid-type energy storage. ω0 is the Thevenin equivalent admittance matrix of the system before the installation of grid-type energy storage, ω0 is the system synchronization frequency, and s is the Laplace operator.

[0047] If the actual generalized short-circuit ratio is greater than the minimum generalized short-circuit ratio ( If the AC / DC hybrid system is equipped with a grid-type energy storage at node c, the system will meet the stability requirements and node c will be included in the set of stable nodes.

[0048] 3) Calculate the investment cost of installing grid-type energy storage on each node in the stable node set, and select the node with the lowest investment cost as the optimal access location for grid-type energy storage.

[0049] The formula for calculating the investment cost W of a grid-type energy storage system connected to a node k in the stable node set in step 3) is as follows:

[0050]

[0051] Among them, W B The construction cost required to install grid-type energy storage at node k, W O The required operation and maintenance costs after installing grid-type energy storage at node k.

[0052] The construction cost mentioned in step 3) of this step The calculation formula is as follows:

[0053]

[0054] Among them, C VSM The unit investment cost of grid-type energy storage; x is the location decision variable, x k =0 indicates that the grid-type energy storage and nodes have access to power lines, x k =1 indicates that the grid-type energy storage and nodes have no wiring supply; d k For the line distance from the grid-type energy storage to the node, C line C represents the unit investment cost of transmission lines. f For fixed costs, PR is the capital recovery factor; the formula for calculating PR is as follows:

[0055]

[0056] Where r is the discount rate and Y is the planning period.

[0057] In step 3), the maintenance cost W is mentioned. Ok The calculation formula is as follows:

[0058]

[0059] Where u is the ratio coefficient of operation and maintenance costs.

[0060] This embodiment presents a grid-based energy storage site selection method to improve the stability and economy of AC / DC hybrid systems, using the minimum generalized short-circuit ratio k. SCRMin As a stability criterion, a systematic set of all stable nodes satisfying stability constraints is selected. Further, the investment cost required to connect each stable node to grid-based energy storage is calculated, and candidate nodes are ranked by economic efficiency. Finally, the node with the lowest investment cost is determined as the optimal connection node. This method can minimize the investment in grid-based energy storage while ensuring the stability of the AC / DC hybrid system. The calculation process is structured and the computational load is controllable, significantly improving the planning efficiency and economic benefits of grid-based energy storage in grids with high penetration rates of new energy sources.

[0061] As an improvement to the above embodiments, this method for site selection of grid-type energy storage to improve the stability and economy of AC / DC hybrid systems further includes, in step 2), a matrix for calculating the actual generalized short-circuit ratio of the AC / DC hybrid system before the installation of grid-type energy storage. Find the corresponding matrix The eigenvectors of the eigenvalues ​​are used to calculate the participation factor p of adding grid-type energy storage to node j in the AC / DC hybrid system. The formula for calculating the participation factor p is as follows:

[0062]

[0063] Among them, u j For matrix The j-th element in the left eigenvector corresponding to the eigenvalue, v j For matrix The j-th element in the right eigenvector corresponding to the eigenvalue.

[0064] The nodes are sorted from largest to smallest based on the value of the participation factor. Then, the actual generalized short-circuit ratio of the system after adding energy storage is calculated in order for each node. Finally, the nodes that meet the system stability requirements after adding grid-type energy storage are included in the set of stable nodes.

[0065] Since a node is more stable when its participation factor is larger, sorting nodes by participation factor from largest to smallest allows for a faster inclusion of nodes that meet system stability requirements after being equipped with grid-type energy storage into the stable node set.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for site selection of grid-type energy storage to improve the stability and economy of AC / DC hybrid systems, characterized in that: include: 1) Use nodes in AC / DC hybrid systems as alternative locations for installing grid-type energy storage; 2) Select nodes based on system stability after connecting nodes in a grid-type energy storage system, including: Calculate the minimum generalized short-circuit ratio of the AC / DC hybrid system before adding grid-type energy storage, and the actual generalized short-circuit ratio of the system after adding grid-type energy storage at a certain node. If the actual generalized short-circuit ratio is greater than the minimum generalized short-circuit ratio, the AC / DC hybrid system meets the system stability requirements after adding grid-type energy storage at that node, and the node is included in the set of stable nodes. 3) Calculate the investment cost of installing grid-type energy storage on each node in the stable node set, and select the node with the lowest investment cost as the optimal access location for grid-type energy storage.

2. The method for site selection of grid-type energy storage to improve the stability and economy of AC / DC hybrid systems according to claim 1, characterized in that: Step 2) calculates the actual generalized short-circuit ratio of the system after adding grid-type energy storage at a certain node. The calculation formula is as follows: , in, It is the Thevenin equivalent admittance matrix of the system after adding grid-type energy storage at the nodes. It is the inverse of the characteristic matrix of the grid-type converter in the AC / DC hybrid system.

3. The method for site selection of grid-type energy storage to improve the stability and economy of AC / DC hybrid systems according to claim 2, characterized in that: Step 2) calculates the minimum generalized short-circuit ratio k of the AC / DC hybrid system before the installation of grid-type energy storage. SCRMin The calculation formula is as follows: , , Where arg(·) is the root operator of the equation. It is the admittance transfer matrix of the grid converter in an AC / DC hybrid system. It is the actual generalized short-circuit ratio of the AC / DC hybrid system before the addition of grid-type energy storage. ω0 is the Thevenin equivalent admittance matrix of the system before the installation of grid-type energy storage, ω0 is the system synchronization frequency, and s is the Laplace operator.

4. The method for site selection of grid-type energy storage to improve the stability and economy of AC / DC hybrid systems according to claim 1, characterized in that: The formula for calculating the investment cost W of adding grid-type energy storage to each node in the stable node set in step 3) is as follows: , Among them, W B The construction cost required to install grid-type energy storage at a node in a stable node cluster, W O The operation and maintenance cost required after installing a grid-type energy storage system on a node in a stable node set.

5. The method for site selection of grid-type energy storage to improve the stability and economy of AC / DC hybrid systems according to claim 4, characterized in that: The construction cost W B The calculation formula is as follows: , Among them, C VSM Let C be the unit investment cost of grid-type energy storage; x is the location decision variable; d is the line distance from the grid-type energy storage to the node; and C is the distance from the grid-type energy storage to the node. line C represents the unit investment cost of transmission lines. f For fixed costs, PR is the capital recovery factor; the formula for calculating PR is as follows: , Where r is the discount rate and Y is the planning period.

6. The method for site selection of grid-type energy storage to improve the stability and economy of AC / DC hybrid systems according to claim 5, characterized in that: The maintenance cost W O The calculation formula is as follows: , Where u is the ratio coefficient of operation and maintenance costs.

7. The method for site selection of grid-type energy storage to improve the stability and economy of AC / DC hybrid systems according to claim 3, characterized in that: Step 2) also includes a matrix for calculating the actual generalized short-circuit ratio of the AC / DC hybrid system before the installation of grid-type energy storage. Find the corresponding matrix The eigenvectors of the eigenvalues ​​are used to calculate the participation factor p of adding grid-type energy storage to node j in the AC / DC hybrid system. The formula for calculating the participation factor p is as follows: , Among them, u j For matrix The j-th element in the left eigenvector corresponding to the eigenvalue, v j For matrix The j-th element in the right eigenvector corresponding to the eigenvalue; The nodes are sorted from largest to smallest based on the value of the participation factor. Then, the actual generalized short-circuit ratio of the system after adding energy storage is calculated in order for each node. Finally, the nodes that meet the system stability requirements after adding grid-type energy storage are included in the set of stable nodes.

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