New energy base voltage support evaluation method and device containing network construction type energy storage

Abstract

The invention belongs to the technical field of power evaluation, and provides a voltage support evaluation method and device for a new energy base containing network construction type energy storage, and the technical scheme comprises the steps: carrying out the load flow calculation according to the obtained system information of the new energy base containing network construction type energy storage, and obtaining a load flow calculation result; according to the load flow calculation result, the reactive power transmission direction of each branch is judged, and a directed graph adjacency matrix is constructed; constructing a voltage support topological graph based on the digraph adjacency matrix; calculating branch reactive power-voltage sensitivity indexes of systems with different complexity degrees from the branch perspective by combining a reactive power-voltage elastic mapping relation of the system; and marking the reactive power-voltage sensitivity value of each branch in the voltage support topological graph, and evaluating the voltage support condition of each branch to the load node and other supported nodes. The problem that a traditional voltage support evaluation method based on single-point or local indexes is difficult to comprehensively reflect the overall voltage support capability of the system is solved.

Description

Technical Field

[0001] This invention belongs to the field of power assessment technology, and in particular relates to a method and device for assessing the voltage support of new energy bases with grid-type energy storage. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Unlike traditional synchronous generators, photovoltaic or wind power has limited reactive power regulation capabilities. When the output level of new energy sources fluctuates or the system load changes significantly, the voltage levels of the distribution and transmission networks are prone to large fluctuations and even exceed limits. Grid-based energy storage, as a new form of energy storage, can provide active power support and, through its grid-connected converter, actively form virtual synchronous machine characteristics, providing the grid with reactive power and voltage support capabilities similar to traditional synchronous machines. Quantifying the specific contribution of grid-based energy storage to voltage support, and further assessing the overall voltage support level of new energy bases with multiple distributed power sources and multi-point energy storage integration, is a current hot topic in power system planning and operation research. If a voltage support assessment model can be constructed for new energy bases containing grid-based energy storage, and a voltage support assessment scheme adapted to complex grid environments can be established, the voltage response characteristics of new energy bases under different operating conditions can be systematically analyzed, the contribution of energy storage systems to voltage regulation can be quantified, and energy storage configuration strategies can be optimized to ensure the safe, stable, and economical operation of new energy bases.

[0004] However, the voltage support issue for new energy bases is currently a key technical challenge under the background of high-proportion renewable energy grid integration. Because new energy sources such as photovoltaics and wind power lack the rotational inertia and reactive power support capabilities of traditional synchronous generators, their large-scale integration leads to a decrease in grid voltage regulation capabilities, increasing the risk of voltage fluctuations and voltage collapse. At the same time, the output of new energy sources is greatly affected by weather conditions, exhibiting randomness and intermittency, making the voltage support requirements more complex and dynamic. Traditional voltage support methods are difficult to fully adapt to the operating characteristics of new energy bases.

[0005] In scenarios with a high proportion of renewable energy, due to the complexity of the actual reactive power flow path, it is difficult to fully reveal the impact of different paths and topologies on voltage support by simply relying on node or branch indicators. In the complex environment of large-scale multi-point energy storage and multi-point new energy access, especially under the multi-source coupling condition where grid-type energy storage provides reactive power support, there is still a lack of systematic evaluation process to quickly and intuitively quantify the overall voltage support level. Summary of the Invention

[0006] To address at least one of the technical problems mentioned above, this invention provides a voltage support assessment method and system for new energy bases with grid-type energy storage. It constructs a voltage support topology based on the "elastic mapping" theory and combines it with a branch reactive power-voltage sensitivity (RPVS) calculation model to quantify the voltage support effect of each branch on load nodes and other supported nodes, thereby achieving a visualized and hierarchical voltage support assessment across the entire network.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: The first aspect of this invention provides a method for evaluating the voltage support of a new energy base with grid-type energy storage, comprising the following steps: Power flow calculation results are obtained by performing power flow calculations based on the acquired information of the new energy base system containing grid-type energy storage. Based on the power flow calculation results, the reactive power transmission direction of each branch is determined, and a directed graph adjacency matrix is ​​constructed; based on the directed graph adjacency matrix, a voltage support topology is constructed. Based on the reactive power-voltage elastic mapping relationship of the system, the sensitivity of a general AC line to the voltage amplitude of the receiving end node is derived, denoted as RPVS; Based on the RPVS value of a typical AC line, the RPVS index change characteristics of the lines after series and parallel connection are analyzed, and the RPVS values ​​of the series line and the parallel line are calculated. The calculated RPVS values ​​of each branch under a general AC line are marked on the voltage support topology diagram. The voltage support of each branch to the load node and other supported nodes is evaluated by combining the RPVS values ​​of the series line and the parallel line.

[0008] Furthermore, the acquired information on the new energy base system including grid-type energy storage includes the network topology of the new energy base, line parameters, transformer parameters, load data, and operating parameters of grid-type energy storage and renewable energy units.

[0009] Furthermore, based on the extracted reactive power transmission data, the reactive power flow of each branch is obtained. ; Calculate the difference in reactive power flow between two adjacent time points. ; according to To determine the direction of reactive power in a branch, assume... A positive value indicates the positive propagation direction, representing the reactive power difference transmitted from the first node to the last node of the branch. If the difference is positive, it means... The positive direction is from the first node to the last node. If the difference is negative, it means that the positive direction is from the last node to the first node.

[0010] Furthermore, the construction of the voltage support topology graph based on the directed graph adjacency matrix includes: Step 1: Start with an unvisited node; Step 2: Along the reactive power transmission path, traverse the power grid graph in a depth-first search, starting from each unvisited adjacent point that has obtained reactive power from the starting point. Step 3: Repeat steps 1 and 2 until all nodes in the power grid have been searched; Step 4: Distribute the nodes and lines in the power grid vertically according to the search order; Step 5: Map the voltage source that generates reactive power regulation to a fixed point, i.e. a support point, map the load to a load, and map the line to a longitudinal spring to construct the grid voltage support topology longitudinal network.

[0011] Furthermore, the sensitivity of a typical AC line to the voltage amplitude at the receiving end is as follows: , , , , in, for right The partial derivative; for right The partial derivative, for right The partial derivative, for right The partial derivative, For line L direction k The active power transmitted at the end, For nodes k Voltage amplitude, For nodes j and k The voltage phase angle difference between them For line L direction k The reactive power transmitted at the end, For nodes j Voltage amplitude, For nodes k Voltage amplitude, Let L be the conductance of the line. Let L be the absolute value of the susceptance of line L. For the line j Terminal-to-ground conductivity; For the line j Terminal-to-ground susceptance.

[0012] Furthermore, when evaluating the voltage support of each branch to load nodes and other supported nodes by combining the RPVS values ​​of series lines and parallel lines, if multiple grid-type energy storage is distributed and connected in a scenario, each grid-type energy storage grid connection point is regarded as multiple upstream support sources in parallel. Combining the series-parallel equivalent relationship of the RPVS values ​​of parallel lines, the support contribution of each energy storage grid connection point to different loads or supported nodes is quantified.

[0013] Furthermore, the evaluation principle for the voltage support capability of series branches is as follows: If the RPVS of a branch in the path approaches 0, it is considered that the branch is disconnected and cannot continue to provide reactive power support to the downstream area. Its downstream node is marked as a high voltage over-limit risk node. The evaluation principle for the voltage support capability of parallel branches is as follows: Multiple support sources can be superimposed through RPVS on different paths. When a single path loses its voltage support capability, the remaining branches provide a transmission path that provides voltage support capability.

[0014] A second aspect of the present invention provides a voltage support assessment system for a new energy base with grid-type energy storage, comprising: The power flow calculation module is used to perform power flow calculations based on the acquired information of the new energy base system with grid-type energy storage to obtain the power flow calculation results. The voltage support topology construction module is used to determine the reactive power transmission direction of each branch based on the power flow calculation results, construct a directed graph adjacency matrix, and construct a voltage support topology based on the directed graph adjacency matrix. The index calculation module, combined with the reactive power-voltage elastic mapping relationship of the system, derives the sensitivity of the reactive power delivered by a general AC line to the receiving end node to the receiving end voltage amplitude, denoted as RPVS; based on the RPVS value of a general AC line, the RPVS index change characteristics of the lines after series and parallel connection are analyzed, and the RPVS values ​​of the series line and the parallel line are calculated. The support evaluation module marks the calculated RPVS values ​​of each branch under a general AC line on the voltage support topology diagram, and evaluates the voltage support of each branch to the load node and other supported nodes by combining the RPVS values ​​of series lines and parallel lines.

[0015] A third aspect of the present invention provides a computer-readable storage medium.

[0016] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps in the voltage support assessment method for a new energy base with grid-type energy storage as described above.

[0017] A fourth aspect of the present invention provides a computer device.

[0018] A computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the steps in the voltage support assessment method for a new energy base with grid-type energy storage as described above.

[0019] Compared with the prior art, the beneficial effects of the present invention are: This invention constructs a voltage support topology based on the "elastic mapping" theory. On the basis of power flow calculation, the RPVS value of the entire network branches can be quickly obtained through linearization and series-parallel equivalence. It quantifies the voltage support effect of each branch on load nodes and other supported nodes without the need for complex numerical optimization or large-scale iteration. It is suitable for online or quasi-online voltage support analysis scenarios, realizes visualized and hierarchical voltage support assessment across the entire network, and can accurately quantify its contribution to system voltage support. This helps to explore the value of energy storage and optimize energy storage deployment and capacity configuration.

[0020] This invention is applicable to various types of voltage support sources, including grid-connected energy storage, conventional energy storage, photovoltaic / wind turbines, and static synchronous compensators (STATCOMs) / static var compensators (SVCs). It can be flexibly deployed according to the real-time operating conditions of each support source (especially the grid-connected operation mode of grid-connected energy storage) without requiring major modifications to the overall method.

[0021] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0022] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0023] Figure 1 This is a flowchart of a voltage support assessment method for a new energy base with grid-type energy storage provided by an embodiment of the present invention; Figure 2 This refers to the single-branch power transmission characteristics provided in the embodiments of the present invention; Figure 3The embodiment of this invention provides a single-degree-of-freedom spring model; Figure 4 This is a simple two-node system branch model provided in an embodiment of the present invention; Figure 5 This is a general AC system branch model provided in the embodiments of the present invention; Figure 6 This is an equivalent model of a general AC system branch series connection provided in an embodiment of the present invention; Figure 7 This invention provides a general AC system branch parallel equivalent model for embodiments of the present invention; Figure 8 The 7-node power distribution system provided in this embodiment of the invention; Figure 9 The voltage support longitudinal topology of the 7-node power distribution system provided in this embodiment of the invention. Detailed Implementation

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0025] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0026] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0027] Terminology Explanation 1. Grid-Forming Energy Storage: Grid-Forming energy storage refers to an energy storage system that can actively control the voltage and frequency of the power system. Unlike traditional grid-following energy storage, grid-forming energy storage systems can autonomously provide power independent of changes in grid voltage and frequency, thus playing a role in the power system similar to that of a traditional synchronous generator.

[0028] Key characteristics of grid-based energy storage systems include: Active power generation and absorption can be adjusted according to the power system's needs to maintain grid frequency stability; Active voltage control allows control of the voltage amplitude and phase at the output, supporting grid voltage stability; Grid-based energy storage systems can simulate the inertia of synchronous generators, providing virtual inertia to help mitigate frequency fluctuations caused by power output fluctuations from new energy sources (such as wind and solar); Grid-based energy storage systems can maintain output during grid faults, helping the grid restore stability; Grid-based energy storage systems can provide independent power supply without grid connection, supporting islanded grid operation; Grid-based energy storage systems are typically equipped with advanced energy management systems that can intelligently schedule power based on grid conditions and the charging and discharging status of energy storage devices.

[0029] Key technologies for grid-based energy storage systems include power electronic converters (PECs), energy storage units (such as batteries), and corresponding control algorithms. These systems are of great significance in modern power systems, especially in grids with high penetration of renewable energy, for improving grid stability and reliability.

[0030] 2. New Energy Bases: New energy bases typically refer to a concentrated geographical area dedicated to the development and utilization of various new energy resources, such as solar, wind, geothermal, and tidal energy. The purpose of these bases is to produce clean electricity on a large scale to support energy supply diversification and reduce environmental impact.

[0031] 3. Voltage Support: Voltage support refers to the ability of a power system to maintain the system voltage within a stable and safe range by regulating reactive power or other control measures. Voltage support is typically provided by generators, reactive power compensation devices (such as static var compensators (SVCs) and static synchronous compensators (STATCOMs), transformer tap changers, parallel capacitors, or reactors.

[0032] 4. Depth-First Search Algorithm: Depth-First Search (DFS) is an algorithm for traversing or searching graphs and trees. Popularized by computer scientist Edsger Dijkstra in the 1960s, it has been widely applied in computer science and artificial intelligence. DFS recursively or using an explicit stack, it delves as deep as possible along a branch of a tree or graph until it reaches the endpoint or the search becomes impossible. It then backtracks to the previous level to continue exploring unvisited paths, thus completing the search process. The main advantages of DFS are its simplicity, low space complexity (especially good in sparse graphs), and suitability for pathfinding and connectivity analysis. It performs well in solving problems such as maze solving, topological sorting, and graph connectivity detection. However, DFS also has some drawbacks, such as the potential for getting stuck in an infinite state space (or without a backtracking mechanism) and the possibility of not finding the optimal solution (in some search problems).

[0033] This invention aims to address the problem that traditional voltage support assessment methods based on single-point or local indicators are insufficient to comprehensively reflect the overall voltage support capability of a large-scale renewable energy base when various voltage support sources (including grid-connected energy storage, photovoltaic, wind power, and other reactive power compensation equipment) are distributedly connected. By constructing a voltage support topology based on the "elastic mapping" theory and combining it with a branch reactive power-voltage sensitivity (RPVS) calculation model, the voltage support effect of each branch on load nodes and other supported nodes is quantified, thereby achieving a visualized and hierarchical voltage support assessment across the entire network. This method is particularly suitable for new energy bases containing grid-connected energy storage, clearly depicting the actual contribution of grid-connected energy storage to voltage support. Furthermore, the method is simple to implement, computationally manageable, and has high engineering practical value.

[0034] Example 1 like Figure 1 As shown in the figure, this embodiment provides a method for evaluating the voltage support of a new energy base with grid-type energy storage, including the following steps: Step 1: Perform power flow calculations based on the acquired information of the new energy base system containing grid-type energy storage to obtain the power flow calculation results; In this embodiment, the acquired system information includes the network topology of the new energy base, line parameters, transformer parameters, load data, and operating parameters (maximum / minimum reactive power output, operating mode, etc.) of the grid-type energy storage and renewable energy units.

[0035] In this embodiment, power flow calculations are performed on the system within a given time period to obtain information such as node voltage amplitude, node voltage phase angle, active / reactive power flow of branches, and operating conditions of grid-type energy storage devices at each time point.

[0036] Step 2: Based on the power flow calculation results, determine the reactive power transmission direction of each branch, construct a directed graph adjacency matrix, and generate a voltage support topology based on the directed graph adjacency matrix. Specifically, the steps include the following: Step 201: Based on the power flow calculation results, determine the reactive power transmission direction of each branch.

[0037] Step 202: Construct a directed graph adjacency matrix based on the reactive power transmission direction of each branch; For branches that may experience bidirectional power flow, the reactive power is uniformly marked according to the positive and negative directions in the power flow calculation. Nodes with reactive power support capabilities (including upstream grid, grid-connected energy storage, grid connection points of photovoltaic / wind power in PV mode, fixed or dynamic reactive power compensation equipment, etc.) are used as "voltage support sources" to form a directed graph of reactive power transmission from the support source node to the load or voltage receiving end node.

[0038] In this embodiment, determining the reactive power transmission direction of each branch includes: Based on the real-time monitoring system, system power flow data is acquired, reactive power transmission data is extracted, and the data for each branch is obtained. The difference in reactive power flow between two adjacent time points That is, reactive power regulation power, let's assume... A positive value indicates the positive propagation direction (assuming the first and last nodes of branch S1 are 1 and 2 respectively, the reactive power difference propagated from node 1 to node 2, if positive, indicates...). The positive direction is from node 1 to node 2; if it is negative, it means the positive direction is from node 2 to node 1, and the first and last nodes of S1 are updated to 2 and 1. Based on the updated first and last nodes, a directed graph connection matrix is ​​constructed. In this embodiment, taking a 33-node system as an example, the process of constructing the directed graph connection matrix includes: first generating... For a matrix of all zeros, if the first and last nodes are 12, then the first row and second column are assigned the value 1; if the first and last nodes are 21, then the second row and first column are assigned the value 1, and so on, until the first and last nodes of all branches are assigned the value.

[0039] Compared to existing undirected graph symmetries, undirected graphs can only provide the connection relationships between nodes, but not the directions.

[0040] Step 203: Generate a voltage support topology graph based on the directed graph adjacency matrix; Specifically, the steps include the following: Step 2031: Select an unvisited node as the starting point; Step 2032: Along the reactive power transmission path, traverse the power grid graph in a depth-first search, starting from each unvisited adjacent point of the starting point that has obtained reactive power from the starting point. Step 2033: Repeat steps 2031 and 2032 until all nodes in the power grid have been searched; Step 2034: Distribute the nodes and lines in the power grid vertically according to the search order; Step 2035: Map the voltage source that generates reactive power regulation power to a fixed point, i.e. a support point, map the load to a load, and map the line to a longitudinal spring, visually presenting the vertical network of the grid voltage support topology. This invention, based on the theory of "elastic mapping," remaps the traditional geographically distributed power grid diagram into a vertical network distributed from top to bottom according to the direction of reactive power regulation. In this vertical network, voltage support sources are located "above" the topology, supported nodes are located "below," and branches are treated as spring units, with their elasticity coefficients related to the branch's reactive power-voltage sensitivity (RPVS). The resulting directed graph of voltage support topology can be used to visualize how, at the same time, multiple sources (grid-based energy storage, photovoltaics, upstream grid, etc.) collaboratively support various load nodes (or other low-voltage level nodes) through their branches.

[0041] Step 3: Combining the reactive power-voltage elastic mapping relationship of the system, derive the sensitivity of the reactive power transmitted from a general AC line to the receiving end node to the receiving end voltage amplitude. Based on the RPVS value of a general AC line, analyze the RPVS index change characteristics after the lines are connected in series and parallel respectively, and calculate the RPVS value of the series line and the RPVS value of the parallel line. In this embodiment, when a branch is connected to a load node or a supported node in a simple single-line connection, the RPVS can be directly calculated using a two-node model. For general multi-branch systems, the RPVS value of each branch can be obtained through linearization of the power flow equations and assumptions of active power balance. For series-parallel circuit structures, equivalent series and parallel RPVS models are established respectively to achieve segmented decoupling of complex network topologies. For scenarios involving structured network energy storage, the grid connection point can be used as the starting node of the supporting source, introducing the RPVS calculation of the corresponding branch. This invention addresses reactive power changes at the node level. Replaced with reactive power changes in branch transmission This allows us to analyze the reactive power regulation capability of branch transmission to the node voltage response capability, that is, the branch transmission voltage support capability.

[0042] Specifically, the steps include the following: Step 301: Map the dynamic response characteristics of reactive power transmission and node voltage of the power grid line to a single-degree-of-freedom spring to obtain the reactive power-voltage elastic coefficient of the branch. Specifically, ignoring line resistance and assuming active power balance in the branches, we focus on the reactive power-voltage characteristics of the branches, mapping the branches as single-degree-of-freedom springs. l , Figure 2 and Figure 3 The branch power transmission characteristics and the single-degree-of-freedom spring are given respectively. l Model. The mapping relationship between reactive power-voltage and the state variables of a single-degree-of-freedom spring within the system is (1): (1), in, Representative function in springs l The force on the spring; assuming end a of the spring is fixed, the spring l Deformation will occur ; For springs l The elastic coefficient. Similarly, the node i Treated as a synchronous node, branch L transmits reactive power regulation power via the line. Give nodes j This will cause its voltage to occur The fluctuation, analogous to the definition of the spring elastic coefficient, gives the definition of the reactive-voltage elastic coefficient of the branch (2): (2); Step 302: Combining the reactive power-voltage elastic mapping relationship of the system, and based on the expressions of active power and reactive power transmitted from the line to the load, derive the branch reactive power-voltage sensitivity index of the two-node system. Inspired by equations (1) and (2), a simple system branch reactive power-voltage sensitivity (RPVS) evaluation model is proposed and derived; Simple two-node system such as Figure 4 As shown, where, E This represents the voltage amplitude at the synchronous generator node. X Indicates the line reactance. V Indicates the voltage amplitude at the load node, then the active power transmitted to the load via the line. and reactive power They are respectively: (3), (4), In the formula: This represents the voltage phase angle difference between the generator connection point and the load connection point.

[0043] The total differential expressions for equations (3) and (4) are: (5), (6), The condition for system balance is that both active power and reactive power are in a balanced state. Here, we first assume that the active power of the system is already in balance and examine whether the reactive power of the system can be balanced. If it cannot be balanced, it means that the assumption is not valid, which means that the reactive power-voltage ratio of the power grid cannot support the assumed active power balance. According to the assumption, let the active power increment in equation (5) be equal to 0, and combine it with equation (6) to eliminate the phase angle difference increment. We can obtain the negative number of the line transmission reactive power sensitivity to node voltage under the active power balance assumption, which is defined as the reactive voltage sensitivity index (RPVS) of the branch: (7), In the formula: subscript ev represent Figure 1 In E End and V End. In equation (7), RPVS is physically the same as in equation (2).

[0044] Step 303: The derivation process of the branch reactive power-voltage sensitivity index based on the two-node system, deriving the sensitivity of the reactive power transmitted from a general AC line to the receiving end node to the receiving end voltage amplitude, i.e., the RPVS index; A typical AC circuit model is as follows: Figure 5 As shown, let the nodes at both ends of AC line L be... j , k The reactive power regulation direction of the line is j arrive k . Figure 5 middle, Let L be the conductance of the line; Let L be the absolute value of the susceptance of line L; For the line j Terminal-to-ground conductivity; For the line j Terminal-to-ground susceptance; For the line k Terminal-to-ground conductivity; For the line k Terminal-to-ground susceptance; Sent via line L k The active and reactive power at the terminal are respectively: (8), (9), In the formula: For nodes j Voltage amplitude; For nodes k Voltage amplitude; For nodes j and k The voltage phase angle difference between them. For line L direction k The active power transmitted at the end; For line L direction k The reactive power transmitted at the end.

[0045] From equations (8) and (9), we can obtain the route L to be sent to k The first-order differential increments of the active and reactive power at the terminals are: (10) (11), In equations (10) and (11), each coefficient represents a partial derivative, the specific expression of which is given in equation (12): (12) In the formula: for right The partial derivative; for right The partial derivative; for right The partial derivative; for right The partial derivative; for right The partial derivative; for right The partial derivative of .

[0046] Based on the assumption of active power balance in the system, let the active power increment in equation (10) be 0, and combine it with equation (11) to eliminate the phase angle difference increment, we can obtain (13): (13) In the formula: and Under the assumption of system vacancy balance, the L-direction of the line are respectively k The sensitivity of reactive power transmission at a node to the amplitudes of the sending and receiving voltages is: (14) (15) Equation (15) is the RPVS index obtained under general AC line conditions, where the subscript... jk Representing branch L j End and k end.

[0047] Step 304: Based on the sensitivity of reactive power transmitted from a general AC line to the receiving end node to the receiving end voltage amplitude, calculate and analyze the RPVS index change characteristics after the line is connected in series and parallel. by Figure 6 The equivalent model of the series connection of the branches shown is as follows: Figure 7 Taking the equivalent model of parallel branch as an example, the RPVS index change characteristics after the line series-parallel equivalent are calculated and analyzed.

[0048] For the equivalent model of the series connection, it is assumed that node 3 has a small reactive power increment. The voltage changes at each node are as follows: , and Ignoring the changes in reactive power consumption of the line, according to equation (13), we have: (16) Eliminate intermediate variables We can obtain: (17) Comparing equation (17) with equation (13), we can obtain that the first term on the right side of equation (17) is the expression for the sensitivity of the reactive power transmitted by the series line to the voltage amplitude of the sending node, and the second term is the expression for the RPVS of the series line, denoted as equation (18): , As can be seen from equation (18), the expression for RPVS of a series circuit is similar to that of a parallel impedance. It belongs to the series decreasing type. If the RPVS of one circuit in a series circuit is 0 (i.e., as long as the numerator is 0), the RPVS value of the entire series branch is equal to 0. This property is very important because it indicates that when the RPVS of a certain circuit is 0, it is equivalent to that branch being in an open state in the voltage-supported topology.

[0049] For parallel circuits, based on the equivalent model of the circuit, we have: (19) In the formula, the first term on the right side of the equation is the expression for the sensitivity of the reactive power transmitted by the parallel line to the voltage amplitude of the sending node, and the second term on the right side of the equation is the expression for the sensitivity of the reactive power transmitted by the parallel line to the voltage amplitude of the receiving node, denoted as Equation (20): (20) According to equation (20), the voltage support capacity of the receiving-end node after the lines are connected in parallel is a superposition relationship. Figure 7 Middle Branch Road When disconnected, =0, It is still possible to use the branch road Continue to give Transmitting reactive power regulation, the equivalent effect of RPVS parallel connection is as follows: .

[0050] Figure 8 It is a 7-node power distribution system. Figure 9 The vertical topology provides voltage support for the 7-node power distribution system. Figure 8 and Figure 9 The middle arrow indicates the direction of reactive power transmission. Node 1 is connected to the upstream power grid, node 2 is connected to a photovoltaic power field, a static var compensator (SVC), and a static var generator (SVG), and node 5 is connected to a grid-type energy storage device. Assuming that all three nodes have voltage support capability, and the load power of nodes 4 and 7 is increased, according to the elastic mapping theory, the following can be drawn: Figure 9 The distribution network voltage support vertical network topology diagram shown also indicates the transmission direction of reactive power regulation on the branches. Compared to Figure 8 The disorder of power transmission direction in reactive power regulation. Figure 7 The reactive power transmission direction of the voltage-supported spatial longitudinal network shown is from top to bottom, from the voltage support source to the voltage-supported point, thus achieving a more intuitive expression of the voltage support topology.

[0051] Step 4: Mark the RPVS values ​​of each branch obtained under the general AC line on the voltage support topology diagram, and evaluate the voltage support of each branch to the load node and other supported nodes. Specifically, the steps include the following: Step 401: Calculate the RPVS value of each branch, and mark the calculated RPVS value of each branch on the corresponding branch in the voltage support topology diagram to obtain the "branch-node" visualization comparison result; Specifically, the voltage support topology diagram shows the direction and path of reactive power transmission from top to bottom. The supporting source (such as grid-type energy storage, upstream grid) is located above the topology, and the supported source (load) is located below. Step 402: Calculate the equivalent RPVS of the series branch, and evaluate the voltage support capability of the series branch based on the equivalent RPVS and the corresponding evaluation principles. In this embodiment, the equivalent RPVS of the series branch is calculated using formula (18); Specifically, the evaluation principle is as follows: if the RPVS of a branch in the path approaches 0, it can be regarded as the branch being disconnected and unable to continue to provide reactive power support to the downstream area. Its downstream node is marked as a "high voltage over-limit risk node". Step 403: Calculate the equivalent RPVS of the parallel branch, and evaluate the voltage support capability of the parallel branch based on the equivalent RPVS and the corresponding evaluation principles. In this embodiment, the equivalent RPVS of the parallel branch is calculated using equation (20) to evaluate the voltage support capability of the parallel branch; The evaluation principle is: multiple support sources (such as grid-type energy storage + photovoltaic) can be superimposed through different paths of RPVS. If a single path loses its voltage support capability, the other branches can still provide a transmission path with voltage support capability. Step 404: Quantify the supporting contribution of grid-connected energy storage. Take the grid-connected energy storage grid connection point as the starting node of the supporting source and calculate the equivalent RPVS of its reactive power regulation transmission path. When multiple energy storages are connected in parallel, the equivalent RPVS of the reactive power regulation transmission path of each grid connection point is superimposed according to Equation (20).

[0052] Specifically, if the grid-connected energy storage is in the "network construction" mode (in which the grid-connected energy storage is in a state of "actively outputting power and forming a voltage / frequency reference," and is regarded as a support source), its output can automatically adjust reactive power according to voltage deviation. Maximum and minimum reactive power constraints need to be set for this node, and its RPVS (Reactive Power Performance Value) on downstream nodes and its potential parallel or series coupling impact on other support sources need to be calculated. For scenarios with multiple grid-connected energy storage systems distributed across multiple nodes, each grid-connected energy storage point can be regarded as multiple "upstream support sources" operating in parallel. Combining the series-parallel equivalence relationship of parallel RPVS, the support contribution of each energy storage grid-connected point to different loads or supported nodes can be quantified.

[0053] This invention marks the RPVS values ​​of each branch on the voltage support topology diagram, realizing visualization of the "branch-node" comparison. The smaller the value, the more "vulnerable" the branch is when transmitting reactive power regulation, and the more limited its support capacity for downstream nodes. In a parallel structure with multiple support sources, the RPVS can be superimposed to improve the overall support effect. Combining information such as node voltage, power flow, and energy storage output, the overall voltage support level of the system is evaluated at different times or under different typical operating conditions (such as peak wind and solar power output, off-peak load, different energy storage strategies, etc.), and "weak branches" with low RPVS and their associated downstream nodes are screened out.

[0054] Example 2 This embodiment provides a voltage support assessment device for new energy bases with grid-type energy storage, including: The power flow calculation module is used to perform power flow calculations based on the acquired information of the new energy base system with grid-type energy storage to obtain the power flow calculation results. The voltage support topology construction module is used to determine the reactive power transmission direction of each branch based on the power flow calculation results, construct a directed graph adjacency matrix, and construct a voltage support topology based on the directed graph adjacency matrix. The index calculation module, combined with the reactive power-voltage elastic mapping relationship of the system, derives the sensitivity of the reactive power delivered by a general AC line to the receiving end node to the receiving end voltage amplitude, denoted as RPVS; based on the RPVS value of a general AC line, the RPVS index change characteristics of the lines after series and parallel connection are analyzed, and the RPVS values ​​of the series line and the parallel line are calculated. The support evaluation module marks the calculated RPVS values ​​of each branch under a general AC line on the voltage support topology diagram, and evaluates the voltage support of each branch to the load node and other supported nodes by combining the RPVS values ​​of series lines and parallel lines.

[0055] It should be noted that the specific implementation of the voltage support assessment device for new energy bases with grid-type energy storage in this embodiment of the invention is similar to the specific implementation of the voltage support assessment method for new energy bases with grid-type energy storage in this embodiment of the invention. Please refer to the description in the method section for details. In order to reduce redundancy, it will not be repeated here.

[0056] Example 3 This embodiment provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps in the voltage support assessment method for a new energy base with grid-type energy storage as described above.

[0057] Example 4 This embodiment provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the steps in the voltage support assessment method for a new energy base with grid-type energy storage as described above.

[0058] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of hardware embodiments, software embodiments, or embodiments combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage and optical storage) containing computer-usable program code.

[0059] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0060] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0061] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0062] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), or random access memory (RAM), etc.

[0063] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for evaluating the voltage support of a new energy base with grid-type energy storage, characterized in that, Includes the following steps: Power flow calculation results are obtained by performing power flow calculations based on the acquired information of the new energy base system containing grid-type energy storage. Based on the power flow calculation results, determine the reactive power transmission direction of each branch and construct a directed graph adjacency matrix; A voltage support topology graph is constructed based on the directed graph adjacency matrix; Based on the reactive power-voltage elastic mapping relationship of the system, the sensitivity of a general AC line to the voltage amplitude of the receiving end node is derived, denoted as RPVS; Based on the RPVS value of a typical AC line, the RPVS index change characteristics of the lines after series and parallel connection are analyzed, and the RPVS values ​​of the series line and the parallel line are calculated. The calculated RPVS values ​​of each branch under a general AC line are marked on the voltage support topology diagram. The voltage support of each branch to the load node and other supported nodes is evaluated by combining the RPVS values ​​of the series line and the parallel line.

2. The voltage support assessment method for a new energy base with grid-type energy storage as described in claim 1, characterized in that, The acquired information on the new energy base system including grid-type energy storage includes the network topology of the new energy base, line parameters, transformer parameters, load data, and operating parameters of grid-type energy storage and renewable energy units.

3. The voltage support assessment method for a new energy base with grid-type energy storage as described in claim 1, characterized in that, The step of determining the reactive power transmission direction of each branch based on the power flow calculation results includes: Based on the extracted reactive power transmission data, the reactive power flow of each branch is obtained. ; Calculate the difference in reactive power flow between two adjacent time points. ; according to To determine the direction of reactive power in a branch, assume... A positive value indicates the positive propagation direction, representing the reactive power difference transmitted from the first node to the last node of the branch. If the difference is positive, it means... The positive direction is from the first node to the last node. If the difference is negative, it means that the positive direction is from the last node to the first node.

4. The voltage support assessment method for a new energy base with grid-type energy storage as described in claim 1, characterized in that, The construction of the voltage support topology graph based on the directed graph adjacency matrix includes: Step 1: Start with an unvisited node; Step 2: Along the reactive power transmission path, traverse the power grid graph in a depth-first search, starting from each unvisited adjacent point that has obtained reactive power from the starting point. Step 3: Repeat steps 1 and 2 until all nodes in the power grid have been searched; Step 4: Distribute the nodes and lines in the power grid vertically according to the search order; Step 5: Map the voltage source that generates reactive power regulation to a fixed point, i.e. a support point, map the load to a load, and map the line to a longitudinal spring to construct the grid voltage support topology longitudinal network.

5. The voltage support assessment method for a new energy base with grid-type energy storage as described in claim 1, characterized in that, The sensitivity of a typical AC line to the voltage amplitude at the receiving end is: ， ， ， ， in, for right The partial derivative; for right The partial derivative, for right The partial derivative, for right The partial derivative, For line L direction k The active power transmitted at the end, For nodes k Voltage amplitude, For nodes j and k The voltage phase angle difference between them For line L direction k The reactive power transmitted at the end For nodes j Voltage amplitude, For nodes k Voltage amplitude, Let L be the conductance of the line. Let L be the absolute value of the susceptance of line L. For the line j Terminal-to-ground conductivity; For the line j Terminal-to-ground susceptance.

6. The voltage support assessment method for a new energy base with grid-type energy storage as described in claim 1, characterized in that, When evaluating the voltage support of each branch to load nodes and other supported nodes by combining the RPVS values ​​of series and parallel lines, if multiple grid-type energy storage is distributed in a scenario, each grid-type energy storage grid connection point is regarded as multiple upstream support sources in parallel. Combining the series-parallel equivalent relationship of the RPVS values ​​of parallel lines, the support contribution of each energy storage grid connection point to different loads or supported nodes is quantified.

7. The voltage support assessment method for a new energy base with grid-type energy storage as described in claim 1, characterized in that, The evaluation principle for the voltage support capability of series branches is as follows: If the RPVS of a branch in the path approaches 0, it is considered that the branch is disconnected and cannot continue to provide reactive power support to the downstream area. Its downstream node is marked as a high voltage over-limit risk node. The evaluation principle for the voltage support capability of parallel branches is as follows: Multiple support sources can be superimposed through RPVS on different paths. When a single path loses its voltage support capability, the remaining branches provide a transmission path that provides voltage support capability.

8. A voltage support assessment device for a new energy base with grid-type energy storage, characterized in that, include: The power flow calculation module is used to perform power flow calculations based on the acquired information of the new energy base system with grid-type energy storage to obtain the power flow calculation results. The voltage support topology construction module is used to determine the reactive power transmission direction of each branch based on the power flow calculation results and construct a directed graph adjacency matrix. A voltage support topology graph is constructed based on the directed graph adjacency matrix; The index calculation module, combined with the reactive power-voltage elastic mapping relationship of the system, derives the sensitivity of the reactive power delivered by a general AC line to the receiving end node to the receiving end voltage amplitude, denoted as RPVS; based on the RPVS value of a general AC line, the RPVS index change characteristics of the lines after series and parallel connection are analyzed, and the RPVS values ​​of the series line and the parallel line are calculated. The support evaluation module marks the calculated RPVS values ​​of each branch under a general AC line on the voltage support topology diagram, and evaluates the voltage support of each branch to the load node and other supported nodes by combining the RPVS values ​​of series lines and parallel lines.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the steps in the voltage support assessment method for a new energy base with grid-type energy storage as described in any one of claims 1-7.

10. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the steps in the voltage support assessment method for a new energy base with grid-type energy storage as described in any one of claims 1-7.

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