Power distribution network control method and device based on distributed power supply and storage medium

Abstract

This invention discloses a distribution network control method, device, and storage medium based on distributed generation (DG). The method involves determining a DG calculation model based on the operating parameters of a wind turbine system, an energy storage system, and a photovoltaic power generation system. Based on the network structure and topology of the DG calculation model, the impedance matrix is ​​simplified to obtain a simplified line parameter model. Each outgoing line bay in the simplified line parameter model is equivalently represented as an independent controlled current source model based on preset node voltage equations. Each independent controlled current source model is then split into impedance matrices according to the topology and equivalently represented to obtain a simplified line fault calculation model. The fault current is determined based on the simplified line fault calculation model, and the DG in the distribution network is controlled based on the fault current. This invention can accurately and reasonably control distribution networks with DG.

Description

Technical Field

[0001] This invention relates to the field of control of distributed power sources in power grids, and more particularly to a control method, device, and storage medium for distribution networks based on distributed power sources. Background Technology

[0002] The number and total amount of distributed photovoltaic (PV) power sources connected to the regional distribution network are growing rapidly. Urban distribution networks have gradually transitioned from the traditional single-source radial power supply structure to a new multi-point power supply structure. In the event of a fault, the connection of a large number of distributed PV power sources will amplify the fault current, thereby affecting the selectivity, sensitivity, and reliability of relay protection operations, posing a significant challenge to relay protection.

[0003] Therefore, how to accurately and reasonably control the distribution network with distributed power sources is an existing problem. Summary of the Invention

[0004] This invention provides a distribution network control method, device, and storage medium based on distributed power sources, which solves the problems of inaccurate and unreasonable control of distribution networks with distributed power sources in current technical solutions.

[0005] To solve the above-mentioned technical problems, the present invention: Firstly, a distribution network control method based on distributed generation is provided, the method comprising: The distributed power generation calculation model is determined based on the operating parameters of the wind turbine system, the energy storage system, and the photovoltaic power generation system. Based on the network structure and topology of the distributed power supply computing model, the impedance matrix in the distributed power supply computing model is simplified to obtain a simplified line parameter model. Based on the preset node voltage equations, each outgoing line interval in the simplified line parameter model is equivalent to its own independent controlled current source model. Based on the independent controlled current source models, the simplified line fault calculation model is obtained by splitting them into impedance matrices according to the topological direction and performing equivalent transformations. The fault current is determined based on the simplified line fault calculation model, and the distributed power sources in the distribution network are controlled based on the fault current.

[0006] In some implementations of the first aspect, the simplification of the impedance matrix in the distributed power supply computing model based on the network structure and topology of the distributed power supply computing model to obtain a simplified line parameter model includes: Based on the network structure of the distributed power computing model, trace back along the topology direction towards the outgoing switch of the substation and record the equipment on the path. Delete all unrecorded devices along the entire line, merge line segments that are connected together and have no branch lines at the connection point, add their impedances, and obtain a simplified line parameter model.

[0007] In some implementations of the first aspect, the preset node voltage equation is a matrix-form KVL equation, which satisfies formula (1). (1) In formula (1), This refers to the terminal voltage of each distributed photovoltaic power source. This represents the positive sequence current amplitude of each distributed photovoltaic power source. This is the bus voltage during a fault; These are the elements in the line impedance matrix; Substituting the expression for the controlled current source into the KVL equation yields the corrected equation; Based on the pre-defined node voltage equations, each outgoing line bay in the simplified line parameter model is equivalent to its own independent controlled current source model, including: Based on the distributed power supply calculation model, the sum of the fault currents of each power supply is determined; Based on the equivalent controlled current source model of each group, the independent controlled current source model is determined, wherein the equivalent controlled current source model of each group satisfies formula (2): (2) In formula (2), The equivalent fault current for each group, The voltage at each point, , The coefficients of the equivalent current sources for each group.

[0008] In some implementations of the first aspect, determining the fault current based on the simplified line fault calculation model includes: The node voltage equations are determined based on the simplified line fault calculation model, wherein the node voltage equations satisfy formula (3) to form a matrix form of the node voltage equations. (3) In formula (3), The current at the fault point, The voltage at the fault point. These are the elements in the impedance matrix, which is of order n+2, where n represents the number of groups. in, The constraints in formula (4) must be satisfied: (4) In formula (4), The equivalent impedance of the upstream power grid referred to the busbar; Based on formulas (1) and (3), the fault current is obtained. .

[0009] In some implementations of the first aspect, the method further includes an automatic reset mechanism, and each branch is equipped with a circuit breaker and a corresponding relay protection device, and meets the operating constraints of current capacity and voltage amplitude limits, and its objective function satisfies formulas (5) and (6): (5) (6) In formulas (5) and (6), This is the amount of load loss; Represents a node and The time between protective actions; This indicates the initial load under switch s; To reconfigure the load, the objective function is divided into two parts: formula (5) and formula (6). Formula (5) represents the load loss, which is the difference between the original load and the load after the distribution network reconfiguration. Distribution network reconfiguration is performed after each N-1 fault, and the network still needs to maintain a radial shape after reconfiguration. Formula (6) represents the load loss amount, which is the difference between the original load and the load after the distribution network reconfiguration. The total time for the main protection to operate after N-1 faults, where the nth fault is the nth fault. The objective function of the operating time characteristic of the relay protection satisfies formula (7): (7) In formula (7), the objective function is summed over n+1 states, where n represents the reconstructed network and 1 represents the original network.

[0010] Secondly, a distribution network control device based on distributed power sources is provided, the device comprising: The determination module is used to determine the distributed power source calculation model based on the operating parameters of the wind turbine system, the energy storage system, and the photovoltaic power generation system. A simplification module is used to simplify the impedance matrix in the distributed power supply computing model based on the network structure and topology direction of the distributed power supply computing model, so as to obtain a simplified line parameter model. The processing module is used to convert each outgoing line interval in the simplified line parameter model into an independent controlled current source model based on the preset node voltage equation. The simplification module is also used to split each independent controlled current source model into an impedance matrix according to the topological direction and perform equivalent transformations to obtain a simplified line fault calculation model. The processing module is used to determine the fault current according to the simplified line fault calculation model, and to control the distributed power sources in the distribution network based on the fault current.

[0011] In some implementations of the second aspect, the simplification module is also used to trace back along the topology direction of the substation outgoing switch based on the network structure of the distributed power supply computing model, and record the devices on the path. In addition, all unrecorded devices along the entire line are deleted, and line segments that are connected together and have no branches at the connection points are merged and their impedances are added together to obtain a simplified line parameter model.

[0012] In some implementations of the second aspect, the preset node voltage equation is a matrix form of KVL equation, which satisfies formula (1). (1) In formula (1), This refers to the terminal voltage of each distributed photovoltaic power source. This represents the positive sequence current amplitude of each distributed photovoltaic power source. This is the bus voltage during a fault; These are the elements in the line impedance matrix; Substituting the expression for the controlled current source into the KVL equation yields the corrected equation; Based on the pre-defined node voltage equations, each outgoing line bay in the simplified line parameter model is equivalent to its own independent controlled current source model, including: Based on the distributed power supply calculation model, the sum of the fault currents of each power supply is determined; Based on the equivalent controlled current source model of each group, the independent controlled current source model is determined, wherein the equivalent controlled current source model of each group satisfies formula (2): (2) In formula (2), The equivalent fault current for each group, The voltage at each point, , The coefficients of the equivalent current sources for each group.

[0013] In some implementations of the second aspect, determining the fault current based on the simplified line fault calculation model includes: The node voltage equations are determined based on the simplified line fault calculation model, wherein the node voltage equations satisfy formula (3) to form a matrix form of the node voltage equations. (3) In formula (3), The current at the fault point, The voltage at the fault point. These are the elements in the impedance matrix, which is of order n+2, where n represents the number of groups. in, The constraints in formula (4) must be satisfied: (4) In formula (4), The equivalent impedance of the upstream power grid referred to the busbar; Based on formulas (1) and (3), the fault current is obtained. .

[0014] Thirdly, a computer storage medium is provided, characterized in that the computer storage medium stores computer program instructions, and the computer program instructions, when executed by a processor, are the method described in the first aspect and some implementations of the first aspect.

[0015] This invention provides a distribution network control method, device, and storage medium based on distributed power sources, which can accurately and reasonably control distribution networks with distributed power sources. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments of the present invention will be briefly introduced below. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a flowchart illustrating a power distribution network control method based on distributed power sources provided in an embodiment of the present invention. Figure 2 This is a schematic diagram of a calculation process provided in an embodiment of the present invention; Figure 3 This is a main protection configuration diagram of a relay protection device for a node system provided in an embodiment of the present invention; Figure 4 This is a switch configuration diagram provided in an embodiment of the present invention; Figure 5 This is a device graphic coordinate information provided in an embodiment of the present invention; Figure 6 This is a schematic diagram of an analysis process provided by an embodiment of the present invention; Figure 7 This is a schematic diagram of the structure of a power distribution network control device based on distributed power sources provided in an embodiment of the present invention; Figure 8 This is a structural diagram of a computing device provided in an embodiment of the present invention. Detailed Implementation

[0018] The features and exemplary embodiments of various aspects of the present invention will now be described in detail. To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only configured to explain the present invention and are not configured to limit the present invention. For those skilled in the art, the present invention can be practiced without some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the present invention by illustrating examples of the invention.

[0019] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes said element.

[0020] In recent years, the number and total amount of distributed photovoltaic (PV) power sources connected to the distribution network in Hefei have grown rapidly. The urban distribution network has gradually transitioned from a traditional single-source radial power supply structure to a new multi-point power supply structure. During faults, the connection of a large number of distributed PV power sources can amplify the fault current, thereby affecting the selectivity, sensitivity, and reliability of relay protection operations, posing a significant challenge to relay protection. At the same time, distributed power supply also provides new solutions for grid reconfiguration and power restoration after faults. Therefore, the applicant has actively conducted research on key technologies for relay protection and control in new urban distribution networks, solving a series of problems such as setting principles, setting calculation models, fault location, grid reconfiguration, and power restoration. This allows for precise and reasonable control of distribution networks with distributed power sources, improving work efficiency and better promoting and ensuring the safe and stable operation of the distribution network, which has significant potential for widespread application.

[0021] The technical solutions provided by the embodiments of the present invention will now be described with reference to the accompanying drawings.

[0022] Figure 1 This is a flowchart illustrating a distribution network control method based on distributed power sources disclosed in this invention. Figure 1As shown, the distribution network control method based on distributed generation can include: S101: Determine the distributed power source calculation model based on the operating parameters of the wind turbine system, the energy storage system, and the photovoltaic power generation system.

[0023] S102: Based on the network structure and topology of the distributed power supply calculation model, the impedance matrix in the distributed power supply calculation model is simplified to obtain a simplified line parameter model.

[0024] S103: Based on the preset node voltage equation, each outgoing line interval in the simplified line parameter model is equivalent to its own independent controlled current source model.

[0025] S104: Based on the independent controlled current source models, the simplified line fault calculation model is obtained by splitting them into impedance matrices according to the topological direction and performing equivalent transformations.

[0026] S105: Determine the fault current based on the simplified line fault calculation model, and control the distributed power sources in the distribution network based on the fault current.

[0027] Specifically, in S101, the doubly-fed induction wind turbine model determined based on the wind turbine system operating parameters is as follows:

[0028]

[0029]

[0030] The energy storage battery system model determined based on the operating parameters of the energy storage system is as follows:

[0031] The photovoltaic power generation system model determined based on the operating parameters of the photovoltaic power generation system is as follows:

[0032]

[0033] According to the "Q / GDW12207-2022 Guidelines for Modeling Distributed Power Supply Stations for Relay Protection Setting Calculations", when simplifying calculations, Negligible impedance can be considered. Under this premise, the impedance matrix is ​​simplified based on the network structure and topology. Each outgoing line bay is equivalent to its own independent "controlled current source" using the node voltage equations, completing parameter preprocessing. When calculating the fault current within this bay, the line model is decomposed into multiple impedance matrices according to the topology and equivalent, resulting in a simplified line fault calculation model. Based on this, the final fault calculation is completed by solving a system of linear equations. This significantly improves calculation speed while ensuring accuracy, and avoids convergence issues. The calculation process is as follows: Figure 2 As shown.

[0034] Combination Figure 2 In S102, the process of simplifying the impedance matrix in the distributed power source computing model based on the network structure and topology of the distributed power source computing model to obtain a simplified line parameter model may include: Based on the network structure of the distributed power computing model, trace back along the topology direction towards the outgoing switch of the substation and record the equipment on the path. Delete all unrecorded devices along the entire line, merge line segments that are connected together and have no branch lines at the connection point, add their impedances, and obtain a simplified line parameter model.

[0035] Specifically, the line parameter model for each outgoing line bay is simplified, including the following steps: 1) Trace back from each distributed photovoltaic power source along the reverse direction of the topology to the substation outgoing switch and record all equipment along the path; 2) Remove all unrecorded equipment from the entire line, merge the line segments that are connected together and have no branch lines at the connection point, add their impedances to obtain a new line segment, and obtain a simplified line parameter model. 3) Generate the impedance matrix: A. The matrix is 1-order symmetric square matrix This represents the number of distributed photovoltaic power sources; B. Generate diagonal elements, which are the sum of all line impedances along the path from each distributed photovoltaic power source back to the substation outgoing switch. Record these segmented impedances. C. Generate other elements row by row, in the process of generating the first... OK When using column elements, use OK The elements of the column and OK Compare the elements of the columns and take the intersection impedance. For example... OK The elements of the column are , OK The elements of the column are Then the first OK The elements of the column are .

[0036] In S103, the preset node voltage equations are KVL equations in matrix form, and the KVL equations satisfy formula (1). (1) In formula (1), This refers to the terminal voltage of each distributed photovoltaic power source. This represents the positive sequence current amplitude of each distributed photovoltaic power source. This is the bus voltage during a fault; These are the elements in the line impedance matrix; Substituting the expression for the controlled current source into the KVL equation yields the corrected equation; Based on the pre-defined node voltage equations, each outgoing line bay in the simplified line parameter model is equivalent to its own independent controlled current source model, including: Based on the distributed power supply calculation model, the sum of the fault currents of each power supply is determined; Based on the equivalent controlled current source model of each group, the independent controlled current source model is determined, wherein the equivalent controlled current source model of each group satisfies formula (2): (2) In formula (2), The equivalent fault current for each group, The voltage at each point, , The coefficients of the equivalent current sources for each group.

[0037] Specifically, the expression for the controlled current source can be substituted into the KVL equations to form a modified equation: The expression for a controlled current source is:

[0038] In the formula, This is the rated current of the inverter.

[0039] The formula for calculating the corrected equation is:

[0040] After sorting, we get

[0041] This set of equations is the final corrected equation.

[0042] Calculate the equivalent controlled current source for each interval. according to Solving for:

[0043] In the formula, This is the sum of the fault currents of all distributed photovoltaic power sources in this interval. and To solve for the equivalent controlled current source coefficients after solving the energy storage battery system model.

[0044] Each interval and After parameter preprocessing, the data is stored in a database and can be directly called when calculating fault current, eliminating the need for real-time calculation.

[0045] Calculating the fault current when a short-circuit fault occurs in a certain interval includes the following steps: (1) Simplify the line parameter model of this outgoing line bay to obtain the impedance matrix. (2) The distributed photovoltaic power source fault calculation model of this interval is grouped and equivalent, including the following steps: 1) Based on the simplified parameter model, the lines are grouped, and the process is traced from each distributed power source towards the main fault path. When a connection point on the main fault path is encountered, the process stops and the "point" and all devices on the path are recorded. 2) Mark each "point" in 1) and all devices on the path connected to it as a "group". The voltage of this point is denoted as . In the energy storage battery system model Replace with And by solving the equations, the equivalent controlled current source model of this "group" is obtained:

[0046] In the formula The equivalent fault current for each "group" For the voltage at each "point", , The coefficients of the equivalent current sources for each "group".

[0047] 3) Remove all devices from the “group” and represent each “group” using the controlled current source model in 2).

[0048] (3) Treat all other bays connected to the same busbar as this bay as a single controlled current source, and calculate using the following formula:

[0049] In the formula, For the fault current of all other bays connected to the same busbar as this bay, , The coefficients representing the equivalent current sources of these intervals. , sum.

[0050] A controlled current source is added in parallel at the location of the source circuit breaker in this bay, and its expression is: Finally, a complete fault calculation model is obtained.

[0051] In S105, the fault current is determined based on the simplified line fault calculation model, including: The node voltage equations are determined based on the simplified line fault calculation model, wherein the node voltage equations satisfy formula (3) to form a matrix form of the node voltage equations. (3) In formula (3), The current at the fault point, The voltage at the fault point. These are the elements of the impedance matrix, which is... Step, Indicates the number of groups; in, The constraints in formula (4) must be satisfied: (4) In formula (4), The equivalent impedance of the upstream power grid referred to the busbar; Based on formulas (1) and (3), the fault current is obtained. .

[0052] Specifically, calculating the fault current when a fault occurs at a certain point in this interval includes the following steps: 1) Forming the nodal voltage equations in matrix form:

[0053] In the formula, The current at the fault point, The voltage at the fault point. These are the elements of the impedance matrix, which is... Step, Indicates the number of "groups".

[0054] in, The following constraints must be met:

[0055] In the formula, The equivalent impedance of the upstream power grid referred to the busbar is a known quantity.

[0056] 2) Substituting equation (1) into the nodal voltage equation, we obtain the corrected equation:

[0057] The target value can be obtained after solving. , , , ... .

[0058] The simplified calculation method described above was used for simulation verification, and the results are as follows: Table 1 Simulation Verification Results

[0059] Comparing the computational efficiency and accuracy of the conventional calculation method and the equivalent model method based on the cluster algorithm, it can be seen that the average calculation time is reduced by more than 90% while the loss calculation accuracy is within 6%. Therefore, the proposed lever-like algorithm is effective for the equivalent of photovoltaic equipment clusters in the current protection setting process of distribution networks, and its applicability is good, meeting the setting requirements. Thus, it can accurately and reasonably control distribution networks with distributed power sources.

[0060] Furthermore, this invention also utilizes distribution network reconfiguration to optimize system operation, isolate faults, and store backups for emergency power outages by changing switch states. Changing the switch states of the distribution network system can transfer some load, thereby improving node voltage levels, reducing network losses, and enhancing system reliability. In the context of distributed power sources and electric vehicles connecting to the distribution network, distribution network reconfiguration is crucial for network stability and post-fault recovery. For overcurrent protection, after distribution network reconfiguration, the system impedance changes due to the altered network structure. If the relay protection device settings are still based on the pre-reconfiguration short-circuit current, the protection range of the protection device may become larger or smaller, resulting in line faults not being eliminated in a timely manner. Therefore, it is necessary to compare network parameters before and after distribution network reconfiguration and establish a reasonable model for optimizing relay protection settings. Currently, traditional topology reconfiguration relies heavily on manual work and does not verify the reconfiguration effect, making it impossible to guarantee that the reconfigured distribution network structure will achieve the best operating performance under current fault conditions. Optimizing the coordination between distribution network reconfiguration and electromechanical protection can minimize load losses to the greatest extent possible.

[0061] This project uses a single-phase equivalent circuit to replace the distribution network model. Each branch is equipped with a circuit breaker and corresponding relay protection device, and operational constraints such as current capacity and voltage amplitude limits are met. Its objective function is as follows: (5) (6) In formulas (5) and (6), This is the amount of load loss; Represents a node and The time between protective actions; This indicates the initial load under switch s; To reconfigure the load, the objective function is divided into two parts: formula (5) and formula (6). Formula (5) represents the load loss, which is the difference between the original load and the load after the distribution network reconfiguration. Distribution network reconfiguration is performed after each N-1 fault, and the network still needs to maintain a radial shape after reconfiguration. Formula (6) represents the load loss amount, which is the difference between the original load and the load after the distribution network reconfiguration. The total time for the main protection to operate after N-1 faults, where the nth fault is the nth fault. The objective function of the operating time characteristic of the relay protection satisfies formula (7): (7) In formula (7), the objective function is the cumulative summation of n+1 states, where n represents the reconstructed network and 1 represents the original network.

[0062] The two terms in the objective function are used to optimize the overcurrent protection action time of the original network and the network after N-1 fault reconfiguration, thereby reducing load loss. These two terms are normalized for easier solution.

[0063] The penalty function is considered in terms of constraints, taking the operational constraints into account. If the constraints are exceeded, a value is added to the objective function; otherwise, the penalty function is 0. For an N-1 fault state, the main protection operates first, quickly isolating the fault. If the main protection fails, the backup protection operates. Therefore, the backup protection should add a Coordination Time Interval (CTI) to the main protection's operating time. The specific expression is as follows:

[0064] In the formula: This is the time for backup protection actions; The main protection action time. For mechanical protection devices. The duration is 0.3s to 0.4s; for digital microcomputer protection, The duration is 0.1s to 0.2s.

[0065] For detecting fault current in relay protection, the short-circuit current should be greater than or equal to the product of the setting value and the current transformer ratio, as expressed below:

[0066] When a fault occurs, the relay protection has a minimum operating time, and the response time should not be too long. The expression is as follows. This project considers time limits of 1.1s and 0.05s for the TMS.

[0067]

[0068] The minimum current and operating time of relay protection are determined by the setting value and the current transformer ratio. The current sensed by the relay protection should be greater than the maximum load current and less than the minimum short-circuit current. Therefore, the setting value should be within a certain range. The limits are 2.5s and 0.5s, respectively. If the current transformer ratio is adjustable within a certain range, the values ​​are 1000 and 40.

[0069]

[0070]

[0071] Maintaining a radial distribution network is beneficial for relay protection to accurately detect fault current direction and operate correctly, while also reducing short-circuit currents in the network. Therefore, the network should be maintained in a radial configuration. This project assumes node 1 is the root node. Consider a symmetric adjacency matrix A with normalized weights and dimensions of... . Time represents node and Connected; a value of 0 indicates unconnected. Additionally, if the first... OK The sum of them is 1, then the first one can be... lines and The column should be removed from A. All of them should be removed. Eliminate the rows if the dimension of A eventually becomes If the result is positive, it indicates that the network is radial. Otherwise, a penalty function should be considered and added to the objective function.

[0072] This project employs the Differential Evolutionary Algorithm (DEA), a population evolution algorithm based on natural selection. In this algorithm, the population size remains constant throughout the optimization process, each individual contains a multi-dimensional vector, and the difference between two randomly selected individuals is used as a random perturbation for the third individual, thereby inducing convergence in terms of distance and orientation information. The algorithm mainly consists of three steps: mutation, crossover, and selection. The specific steps are as follows: (1) Input: Considering the original network In the event of a fault, the relay protection system will activate to minimize load loss. A fault can occur at any node; after a fault occurs, that node will be isolated to prevent impact on the downstream network. Network reconstruction should be performed after a failure.

[0073] (2) Initialization: , , and Randomly select initial values ​​within the constraints. These initial values ​​cover n network structures.

[0074] (3) Short-circuit current calculation: Calculate the short-circuit current for each switching state. Short-circuit current under various fault conditions, including the short-circuit current of the original network.

[0075] (4) Fitness function calculation: Calculate the objective function value. If there are any deviations from the limit, add a penalty function. The optimal fit value should satisfy the following conditions: A type of network structure.

[0076] (5) Vector Update: Based on the mutation strategy of differential evolution algorithm, for vectors containing The set of faulty switches and , and The vector is updated.

[0077] (6) Stopping condition: The problem continues to optimize until the penalty function is 0. Therefore, the optimization stops when the objective function value no longer decreases or the maximum number of iterations is reached.

[0078] This project simulated the proposed method, and the main protection configuration diagram of the relay protection device for this node system is shown below. Figure 3 The protection number is the same as the previous node number; special numbers are marked in the diagram. System data can be found in the literature. This network is connected to a system with an impedance of 0.015. ( The main network is defined as per-unit value. The four lines of this node system can be reconfigured, with the switch configuration as follows: Figure 4 Each branch in the system contains one circuit breaker, and the system has a total of 36 circuit breakers.

[0079] The simulation examined the switching actions after topology reconfiguration under different node failures. Using the traditional method, a 31-node failure occurred... If the relay protection fails to meet the operating sequence after a fault, it will cause the switches at nodes 18, 33, and 32 to trip. After node 30 is reconfigured, the relay protection will malfunction.

[0080] Table 1. Reconstructed Switch Action Sequence

[0081] If the optimization model of this project is used, the sequence of relay protection actions is correct. The relay protection actions are shown in Table 2. If node 18 occurs... The fault occurred, and the relay protection operation sequence is R17, R16, which meets the required operating sequence. Similarly, a fault occurred at node 10. The fault, the relay protection operation sequence is R9, R8; the fault occurs at node 28. In the event of a fault, the relay protection operation sequence is R27, R26. Therefore, the model proposed in this invention is applicable to the optimized coordination of protection devices after distribution network reconfiguration.

[0082] Table 2 shows the reconstructed sequence of switching actions using the differential evolution algorithm.

[0083] The optimization of this project has improved the relay protection coordination phase. The main protection will act first under any fault, and the backup protection will act if the main protection fails. Inadequate optimization of the protection coordination timing phase can lead to protection maloperation and failure to operate. While maintaining the radial distribution network structure after reconfiguration, the setting values, time-current multiples, and other parameters of the protection devices in each branch are optimized. The parameters are optimized to minimize the load loss after reconstruction.

[0084] This invention establishes a "controlled current source" model for distributed power sources that conforms to the latest State Grid standard "Q / GDW12207-2022 Guidelines for Modeling Distributed Power Source Stations for Relay Protection Setting Calculation". Combining the operating characteristics and topology of the distribution network, a simplified calculation method is proposed. While ensuring the accuracy of setting calculation, the calculation efficiency is improved, reducing the average setting calculation time of active distribution networks by more than 90%. This significantly improves the efficiency of setting calculation in active distribution networks, enabling precise and reasonable control of distribution networks with distributed power sources.

[0085] Furthermore, an active distribution network automatic reconfiguration mechanism has been established. From the perspective of optimal protection configuration coordination, this ensures that under temporary operation methods after reconfiguration, the power outage scope can be minimized and load losses reduced in the event of a sudden fault. This makes distribution network reconfiguration based on evidence, rather than relying solely on manual experience. It reduces protection mismatch issues caused by distribution network reconfiguration and effectively improves the reliability of power supply in distribution network operation.

[0086] Furthermore, in traditional setting modes, relay protection setting calculations do not consider the actual opening and closing states of field switches and load information. Changes in operating modes may lead to insufficient sensitivity and selectivity in the protection. The diagram and model management system contains sufficiently complete line diagram and model information and operating data. The research will involve key data interaction with the diagram and model management system to ensure that the settings can adapt to changes in line operating modes.

[0087] 1. Acquisition of basic line diagram data The graphic files exported by the graphic model management system are in CIME+SVG format. The CIME file contains complete device information and its topology connections, while the SVG file contains the device's graphic coordinate information, such as... Figure 5 As shown.

[0088] During file transfer, the map and model management system sends the map and model files to the dispatch server via SFTP, storing them in a specified folder. The distribution network adjustment system automatically retrieves the map and model files from the folder and then parses them within the program. Figure 6 As shown.

[0089] Before using the distribution network adjustment system, it is necessary to parse the diagrams of each line. To reduce the amount of data maintenance required by staff in the early stages, a batch import method can be used. First, all the required diagrams are exported from the diagram management system. Then, the distribution network program can directly use the batch import function, select the folder or compressed package where the diagrams are stored, and parse all the diagrams at once, easily and conveniently creating the initial diagram data.

[0090] In other words, this invention also establishes a data interaction mechanism with the diagram and model management system to achieve timely synchronization of switch status and load status. When changes occur in operation, the equipment status information in the distribution network setting system can be updated in a timely manner, and the selectivity and sensitivity of the protection settings can be verified. If the relay protection requirements are not met, the settings can be readjusted in a timely manner, reducing or even avoiding the problem of distribution network over-tripping caused by untimely updates of protection settings, and effectively ensuring the adaptability of protection settings to the operating mode.

[0091] and Figure 1 Corresponding to the distribution network control method based on distributed generation, this invention also provides a distribution network control device based on distributed generation, such as... Figure 7 As shown, the device includes: Module 701 is used to determine the distributed power source calculation model based on the operating parameters of the wind turbine system, the operating parameters of the energy storage system, and the operating parameters of the photovoltaic power generation system. The simplification module 702 is used to simplify the impedance matrix in the distributed power supply calculation model based on the network structure and topology direction of the distributed power supply calculation model, so as to obtain a simplified line parameter model. Processing module 703 is used to convert each outgoing line interval in the simplified line parameter model into an independent controlled current source model based on a preset node voltage equation. The simplification module 702 is also used to split each independent controlled current source model into an impedance matrix according to the topological direction and perform equivalent transformation to obtain a simplified line fault calculation model. The processing module 703 is used to determine the fault current according to the simplified line fault calculation model, and to control the distributed power sources in the distribution network based on the fault current.

[0092] In one embodiment, the simplification module 702 is also used to trace back along the topology direction of the substation outgoing switch based on the network structure of the distributed power supply computing model and record the devices on the path. In addition, all unrecorded devices along the entire line are deleted, and line segments that are connected together and have no branches at the connection points are merged and their impedances are added together to obtain a simplified line parameter model.

[0093] In one embodiment, the preset node voltage equation is a matrix form of KVL equation, which satisfies formula (1). (1) In formula (1), This refers to the terminal voltage of each distributed photovoltaic power source. This represents the positive sequence current amplitude of each distributed photovoltaic power source. This is the bus voltage during a fault; These are the elements in the line impedance matrix; Substituting the expression for the controlled current source into the KVL equation yields the corrected equation; Based on the pre-defined node voltage equations, each outgoing line bay in the simplified line parameter model is equivalent to its own independent controlled current source model, including: Based on the distributed power supply calculation model, the sum of the fault currents of each power supply is determined; Based on the equivalent controlled current source model of each group, the independent controlled current source model is determined, wherein the equivalent controlled current source model of each group satisfies formula (2): (2) In formula (2), The equivalent fault current for each group, The voltage at each point, , The coefficients of the equivalent current sources for each group.

[0094] In one embodiment, determining the fault current based on the simplified line fault calculation model includes: The node voltage equations are determined based on the simplified line fault calculation model, wherein the node voltage equations satisfy formula (3) to form a matrix form of the node voltage equations. (3) In formula (3), The current at the fault point, The voltage at the fault point. These are the elements in the impedance matrix, which is of order n+2, where n represents the number of groups. in, The constraints in formula (4) must be satisfied: (4) In formula (4), The equivalent impedance of the upstream power grid referred to the busbar; Based on formulas (1) and (3), the fault current is obtained. .

[0095] Figure 8 This is a structural diagram of a computing device provided in an embodiment of the present invention. Figure 8 As shown, the computing device 800 includes an input interface 801, a central processing unit 802, a memory 803, and an output interface 804. The input interface 801, central processing unit 802, memory 803, and output interface 804 are interconnected via a bus 810.

[0096] Figure 8 The computing device shown can also be implemented as an execution device for a power distribution network control method based on distributed power sources. The computing device may include a processor and a memory storing computer-executable instructions. When the processor executes the computer-executable instructions, it can implement the power distribution network control method based on distributed power sources provided in the embodiments of the present invention.

[0097] This invention also provides a computer-readable storage medium storing computer program instructions; when executed by a processor, the computer program instructions implement the power distribution network control method based on distributed power sources provided in this invention.

[0098] It should be clarified that the present invention is not limited to the specific configurations and processes described above and shown in the figures. For the sake of brevity, detailed descriptions of known methods are omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of the present invention is not limited to the specific steps described and shown. Those skilled in the art can make various changes, modifications, and additions, or change the order of steps, after understanding the spirit of the present invention.

[0099] The functional blocks shown in the above-described structural diagram can be implemented as hardware, software, firmware, or a combination thereof. When implemented in hardware, they can be, for example, electronic circuits, application-specific integrated circuits (ASICs), appropriate firmware, plug-ins, function cards, etc. When implemented in software, the elements of this invention are programs or code segments used to perform the required tasks. Programs or code segments can be stored on a machine-readable medium or transmitted over a transmission medium or communication link via data signals carried on a carrier wave. "Machine-readable medium" can include any medium capable of storing or transmitting information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, read-only memory (ROM), flash memory, erasable read-only memory (EROM), floppy disks, compact disc read-only memory (CD-ROM), optical disks, hard disks, fiber optic media, radio frequency (RF) links, etc. Code segments can be downloaded via computer networks such as the Internet, intranets, etc.

[0100] It should also be noted that the exemplary embodiments mentioned in this invention describe methods or systems based on a series of steps or apparatus. However, this invention is not limited to the order of the steps described above; that is, the steps can be performed in the order mentioned in the embodiments, or in a different order, or several steps can be performed simultaneously.

[0101] The aspects of this disclosure have been described above with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this disclosure. It should be understood that each block in 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, a special-purpose computer, or other programmable data processing apparatus to produce a machine such that these instructions, executable via the processor of the computer or other programmable data processing apparatus, enable the implementation of the functions / actions specified in one or more blocks of the flowchart illustrations and / or block diagrams. Such a processor can be, but is not limited to, a general-purpose processor, a special-purpose processor, a special application processor, or a field-programmable logic circuit. It is also understood that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can also be implemented by special-purpose hardware performing the specified functions or actions, or can be implemented by a combination of special-purpose hardware and computer instructions.

[0102] The above description is merely a specific embodiment of the present invention. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, modules, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here. It should be understood that the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the protection scope of the present invention.

Claims

1. A distribution network control method based on distributed generation, characterized in that, The method includes: The distributed power generation calculation model is determined based on the operating parameters of the wind turbine system, the energy storage system, and the photovoltaic power generation system. Based on the network structure and topology of the distributed power supply computing model, the impedance matrix in the distributed power supply computing model is simplified to obtain a simplified line parameter model. Based on the preset node voltage equations, each outgoing line interval in the simplified line parameter model is equivalent to its own independent controlled current source model. Based on the independent controlled current source models, the simplified line fault calculation model is obtained by splitting them into impedance matrices according to the topological direction and performing equivalent transformations. The fault current is determined based on the simplified line fault calculation model, and the distributed power sources in the distribution network are controlled based on the fault current.

2. The method according to claim 1, characterized in that, Based on the network structure and topology of the distributed power source computing model, the impedance matrix in the distributed power source computing model is simplified to obtain a simplified line parameter model, including: Based on the network structure of the distributed power computing model, trace back along the topology direction towards the outgoing switch of the substation and record the equipment on the path. Delete all unrecorded devices along the entire line, merge line segments that are connected together and have no branch lines at the connection point, add their impedances, and obtain a simplified line parameter model.

3. The method according to claim 1, characterized in that, The preset node voltage equations are KVL equations in matrix form, and the KVL equations satisfy formula (1). (1) In formula (1), This refers to the terminal voltage of each distributed photovoltaic power source. This represents the positive sequence current amplitude of each distributed photovoltaic power source. This is the bus voltage during a fault; These are the elements in the line impedance matrix; Substituting the expression for the controlled current source into the KVL equation yields the corrected equation; Based on the pre-defined node voltage equations, each outgoing line bay in the simplified line parameter model is equivalent to its own independent controlled current source model, including: Based on the distributed power supply calculation model, the sum of the fault currents of each power supply is determined; Based on the equivalent controlled current source model of each group, the independent controlled current source model is determined, wherein the equivalent controlled current source model of each group satisfies formula (2): (2) In formula (2), The equivalent fault current for each group, The voltage at each point, , The coefficients of the equivalent current sources for each group.

4. The method according to claim 1, characterized in that, Determining the fault current based on the simplified line fault calculation model includes: The node voltage equations are determined based on the simplified line fault calculation model, wherein the node voltage equations satisfy formula (3) to form a matrix form of the node voltage equations. (3) In formula (3), The current at the fault point, The voltage at the fault point. These are the elements in the impedance matrix, which is of order n+2, where n represents the number of groups. in, The constraints in formula (4) must be satisfied: （4） In formula (4), The equivalent impedance of the upstream power grid referred to the busbar; Based on formulas (1) and (3), the fault current is obtained. .

5. The method according to claim 1, characterized in that, The method also includes an automatic reset mechanism, and each branch is equipped with a circuit breaker and a corresponding relay protection device, and meets the current capacity and voltage amplitude limit operation constraints. Its objective function satisfies formulas (5) and (6): (5) (6) In formulas (5) and (6), This is the amount of load loss; Represents a node and The time between protective actions; This indicates the initial load under switch s; To reconfigure the load, the objective function is divided into two parts: formula (5) and formula (6). Formula (5) represents the load loss, which is the difference between the original load and the load after the distribution network reconfiguration. Distribution network reconfiguration is performed after each N-1 fault, and the network still needs to maintain a radial shape after reconfiguration. Formula (6) represents the load loss amount, which is the difference between the original load and the load after the distribution network reconfiguration. The total time for the main protection to operate after N-1 faults, where the nth fault is the nth fault. The objective function of the operating time characteristic of the relay protection satisfies formula (7): (7) In formula (7), the objective function is the cumulative summation of n+1 states, where n represents the reconstructed network and 1 represents the original network.

6. A distribution network control device based on distributed power sources, characterized in that, The device includes: The determination module is used to determine the distributed power source calculation model based on the operating parameters of the wind turbine system, the energy storage system, and the photovoltaic power generation system. A simplification module is used to simplify the impedance matrix in the distributed power supply computing model based on the network structure and topology direction of the distributed power supply computing model, so as to obtain a simplified line parameter model. The processing module is used to convert each outgoing line interval in the simplified line parameter model into an independent controlled current source model based on the preset node voltage equation. The simplification module is also used to split each independent controlled current source model into an impedance matrix according to the topological direction and perform equivalent transformations to obtain a simplified line fault calculation model. The processing module is used to determine the fault current according to the simplified line fault calculation model, and to control the distributed power sources in the distribution network based on the fault current.

7. The apparatus according to claim 6, characterized in that, The simplification module is also used to trace back along the topology direction of the substation outgoing switch based on the network structure of the distributed power supply computing model and record the equipment on the path. In addition, all unrecorded devices along the entire line are deleted, and line segments that are connected together and have no branches at the connection points are merged and their impedances are added together to obtain a simplified line parameter model.

8. The apparatus according to claim 6, characterized in that, The preset node voltage equations are KVL equations in matrix form, and the KVL equations satisfy formula (1). (1) In formula (1), This refers to the terminal voltage of each distributed photovoltaic power source. This represents the positive sequence current amplitude of each distributed photovoltaic power source. This is the bus voltage during a fault; These are the elements in the line impedance matrix; Substituting the expression for the controlled current source into the KVL equation yields the corrected equation; Based on the pre-defined node voltage equations, each outgoing line bay in the simplified line parameter model is equivalent to its own independent controlled current source model, including: Based on the distributed power supply calculation model, the sum of the fault currents of each power supply is determined; Based on the equivalent controlled current source model of each group, the independent controlled current source model is determined, wherein the equivalent controlled current source model of each group satisfies formula (2): (2) In formula (2), The equivalent fault current for each group, The voltage at each point, , The coefficients of the equivalent current sources for each group.

9. The apparatus according to claim 6, characterized in that, Determining the fault current based on the simplified line fault calculation model includes: The node voltage equations are determined based on the simplified line fault calculation model, wherein the node voltage equations satisfy formula (3) to form a matrix form of the node voltage equations. (3) In formula (3), The current at the fault point, The voltage at the fault point. These are the elements in the impedance matrix, which is of order n+2, where n represents the number of groups. in, The constraints in formula (4) must be satisfied: （4） In formula (4), The equivalent impedance of the upstream power grid referred to the busbar; Based on formulas (1) and (3), the fault current is obtained. .

10. A computer storage medium, characterized in that, The computer storage medium stores computer program instructions, which, when executed by a processor, implement the method as described in any one of claims 1-5.

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