Fault reconstruction method and device of power distribution network, terminal equipment and storage medium

Abstract

The invention discloses a fault reconstruction method and device for a power distribution network, terminal equipment and a storage medium, and belongs to the technical field of power grid reconstruction, and the method comprises the steps: obtaining the power data of a fault period of the power distribution network in real time, and the number of time periods between the current moment and the fault occurrence moment; then, according to the power data and the time period number, with the purpose of minimizing the sum of the load power loss amount and the power failure cost, a line recovery optimization model and corresponding constraint conditions are constructed; and finally, under each constraint condition, solving the line recovery optimization model to obtain the line switch state of each line when the sum of the load power loss and the power failure cost is minimum, and performing fault reconstruction on the current power distribution network according to the line switch state. Through the implementation of the method and the device, the problem that the obtained reconstruction scheme is unreasonable due to the fact that the loss of the load in the power failure period cannot be accurately evaluated when the static constant load power failure loss is used for power grid reconstruction in the prior art can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of power grid reconstruction, and in particular to a method, apparatus, terminal equipment and storage medium for fault reconstruction of a distribution network. Background Art

[0002] With the rapid development of China's power system, the requirements for distribution network reliability and safety have also increased. At the same time, the application of intelligent devices such as distribution automation terminals has significantly improved the detectability and controllability of the distribution network, enabling precise regulation and control of switches. This has also laid the foundation for maximizing power restoration through network reconstruction and islanding in the event of a distribution network failure.

[0003] Existing research on distribution network fault recovery strategies typically treats load outage losses as static constant values ​​for economic evaluation (e.g., using fixed unit outage costs or linear models based on load priority classification). However, multiple studies have demonstrated through empirical analysis that user sensitivity to power outages is significantly time-dependent, with unit load outage losses exponentially decaying with outage duration. Therefore, grid reconstruction based on static constant load outage losses overestimates the actual losses of long-term outage loads and underestimates the hidden losses of critical loads requiring long-term stable power supply (e.g., medical facilities and communication base stations), leading to an imbalance in resource allocation. Consequently, existing technologies suffer from inaccurate outage cost calculations, resulting in irrational fault reconstruction schemes. Summary of the Invention

[0004] The present invention provides a distribution network fault reconstruction method, apparatus, terminal device and storage medium, which can solve the problem in the prior art of using static constant load power outage loss for power grid reconstruction, resulting in an inability to accurately assess load losses during a power outage, and causing the resulting reconstruction scheme to be unreasonable.

[0005] An embodiment of the present invention provides a method for fault reconstruction of a distribution network, comprising:

[0006] Real-time acquisition of power data during distribution network faults, as well as the number of time periods between the current time and the time of the fault; wherein the power data includes: node load active power, node user power outage loss cost, loss attenuation constant, load power failure status, number of independent power sources, number of power supply loops, number of branches in the power supply loop, node injection power, node outflow power, distributed power generation output, node reactive load, branch current, line loss, line resistance, line reactance, node voltage, node rated voltage, and branch maximum capacity;

[0007] Based on the aforementioned power data and time periods, and with the goal of minimizing the sum of load loss and outage costs, a line restoration optimization model and corresponding constraints are constructed. These constraints include: grid radial structure constraints, node active power constraints, node reactive power constraints, line voltage drop constraints, capacity constraints, and voltage constraints.

[0008] Under the above constraints, the line restoration optimization model is solved to obtain the line switch status of each line when the sum of load loss and power outage cost is minimized, and the current distribution network is fault reconstructed based on the above line switch status.

[0009] Furthermore, the objective function of the above line restoration optimization model is:

[0010]

[0011] f=min(β1f1+β2f2)

[0012] Where f1 represents the load loss, n represents the set of all nodes in the distribution network, i represents node i, ω i represents the preset load weight coefficient of node i, P L,i represents the load active power of node i, x i represents the load power failure state of node i, f2 represents the power outage cost, C i represents the power outage loss cost of the user at the time of the fault of node i, γ represents the loss attenuation constant, t s represents the number of time periods between the current time and the time when the fault occurs, f represents the value of the objective function, β1 represents the preset weight corresponding to the load loss, and β2 represents the preset weight corresponding to the power outage cost.

[0013] Furthermore, the radial structure of the power grid is constrained as follows:

[0014]

[0015] Where Z i,j Indicates the line switch status of the line from node i to node j. When Z i,j =1, indicating that the line switch state of the line from node i to node j is the line closed state. i,j = 0, indicating that the line switch state of the line from node i to node j is the line disconnected state, N represents the total number of nodes in the distribution network, N s Indicates the number of independent power supplies, M l Indicates the number of branches in the power supply loop l, l represents the power supply loop l, Z (i,j),l Indicates the line switch status of the line between node i and node j in the power supply loop l;

[0016] The active power constraint of the above nodes is:

[0017]

[0018] Where, represents the active power injected from node i to node j at time t, represents the active power outflow from node j at the current time t, r i,j represents the line resistance from node i to node j at time t, It represents the square term of the branch current on the branch from node i to node j at time t, represents the active power of the load of node j at time t, represents the output of distributed generation at node j at time t;

[0019] The reactive power constraint of the above nodes is:

[0020]

[0021] Where, represents the reactive power injected from node i to node j at time t, represents the reactive power outflow from node j at time t, x i,j represents the line reactance of the line from node i to node j, represents the node reactive load of node j at time t, represents the reactive power output of the distributed generation at node j at time t;

[0022] The above line voltage drop constraint is:

[0023]

[0024] Where m i,j represents a constant determined by the line switch state of the line between node i and node j, and M represents a constant with a large value. It represents the line switch state of the line from node i to node j at time t. When , it means that at time t, the line switch state of the line from node i to node j is the line closed state. When , it means that at time t, the line switch state of the line from node i to node j is the line disconnected state, represents the square term of the node voltage of node i at time t, represents the square term of the node voltage of node j at time t;

[0025] The above capacity constraints are:

[0026]

[0027] Where S max Indicates the maximum capacity of the branch;

[0028] The above voltage constraints are:

[0029]

[0030] Where y represents the allowable voltage deviation, U N Indicates the rated voltage of the node.

[0031] Furthermore, the current distribution network is reconfigured according to the above-mentioned line switch status, including:

[0032] Determining, based on the line switch state, a first node set on a line in a line closed state in the distribution network;

[0033] According to the first node set, power supply is restored to the nodes in the first node set in the current power distribution network.

[0034] Based on the above method embodiment, the present invention provides a corresponding device embodiment;

[0035] The present invention provides a fault reconstruction device for a distribution network, comprising:

[0036] Data acquisition module, model building module and distribution network reconstruction module;

[0037] The data acquisition module is used to obtain in real time the power data during the distribution network fault period, as well as the number of time periods between the current time and the time when the fault occurs; wherein the power data includes: node load active power, node user power outage loss cost, loss attenuation constant, load power failure status, number of independent power sources, number of power supply loops, number of branches in the power supply loop, node injection power, node outflow power, distributed power supply output, node reactive load, branch current, line loss, line resistance, line reactance, node voltage, node rated voltage, and branch maximum capacity;

[0038] The model building module is configured to construct a line restoration optimization model and corresponding constraints based on the power data and the time periods, with the goal of minimizing the sum of load loss and outage cost; wherein the constraints include: grid radial structure constraints, node active power constraints, node reactive power constraints, line voltage drop constraints, capacity constraints, and voltage constraints;

[0039] The above-mentioned distribution network reconstruction module is used to solve the above-mentioned line restoration optimization model under the above-mentioned constraints, obtain the line switch status of each line when the sum of the load loss and the power outage cost is minimized, and reconstruct the current distribution network according to the above-mentioned line switch status.

[0040] Furthermore, the objective function of the above line restoration optimization model is as follows:

[0041]

[0042] f=min(β1f1+β2f2)

[0043] Where f1 represents the load loss, n represents the set of all nodes in the distribution network, i represents node i, ω i represents the preset load weight coefficient of node i, P L,i represents the load active power of node i, x i represents the load power failure state of node i, f2 represents the power outage cost, C i represents the power outage loss cost of the user at the time of the fault of node i, γ represents the loss attenuation constant, t s represents the number of time periods between the current time and the time when the fault occurs, f represents the value of the objective function, β1 represents the preset weight corresponding to the load loss, and β2 represents the preset weight corresponding to the power outage cost.

[0044] Furthermore, the radial structure of the power grid is constrained as follows:

[0045]

[0046] Where Z i,j Indicates the line switch status of the line from node i to node j. When Z i,j =1, indicating that the line switch state of the line from node i to node j is the line closed state. i,j = 0, indicating that the line switch state of the line from node i to node j is the line disconnected state, N represents the total number of nodes in the distribution network, N s Indicates the number of independent power supplies, M l Indicates the number of branches in the power supply loop l, l represents the power supply loop l, Z (i,j),l Indicates the line switch status of the line between node i and node j in the power supply loop l;

[0047] The active power constraint of the above nodes is:

[0048]

[0049] Where, represents the active power injected from node i to node j at time t, represents the active power outflow from node j at the current time t, r i,j represents the line resistance from node i to node j at time t, It represents the square term of the branch current on the branch from node i to node j at time t, represents the active power of the load of node j at time t, represents the output of distributed generation at node j at time t;

[0050] The reactive power constraint of the above nodes is:

[0051]

[0052] Where, represents the reactive power injected from node i to node j at time t, represents the reactive power outflow from node j at time t, x i,j represents the line reactance of the line from node i to node j, represents the node reactive load of node j at time t, represents the reactive power output of the distributed generation at node j at time t;

[0053] The above line voltage drop constraint is:

[0054]

[0055] Where m i,j represents a constant determined by the line switch state of the line between node i and node j, and M represents a constant with a large value. It represents the line switch state of the line from node i to node j at time t. When , it means that at time t, the line switch state of the line from node i to node j is the line closed state. When , it means that at time t, the line switch state of the line from node i to node j is the line disconnected state, represents the square term of the node voltage of node i at time t, represents the square term of the node voltage of node j at time t;

[0056] The above capacity constraints are:

[0057]

[0058] Where S max Indicates the maximum capacity of the branch;

[0059] The above voltage constraints are:

[0060]

[0061] Where y represents the allowable voltage deviation, U N Indicates the rated voltage of the node.

[0062] Furthermore, the distribution network reconstruction module includes:

[0063] a first node set determining unit and a node power restoration unit;

[0064] The first node set determining unit is configured to determine, based on the line switch state, a first node set on a line in a line closed state in the distribution network;

[0065] The node power supply restoration unit is configured to restore power supply to nodes within the first node set in the current power distribution network based on the first node set.

[0066] Based on the above method embodiment, the present invention provides a corresponding terminal device embodiment;

[0067] The present invention provides a terminal device, comprising a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements a distribution network fault reconstruction method described in any embodiment of the present invention.

[0068] Based on the above method embodiment, the present invention provides a storage medium embodiment;

[0069] The present invention provides a storage medium comprising a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, the method for fault reconstruction of a distribution network described in any embodiment of the present invention is implemented.

[0070] The embodiments of the present invention have the following beneficial effects:

[0071] The present invention provides a method, apparatus, terminal device and storage medium for fault reconstruction of a distribution network. The method comprises: obtaining power data during a distribution network fault in real time, as well as the number of time periods between the current moment and the moment of the fault; wherein the power data comprises: node load active power, node user power outage loss cost, loss attenuation constant, load power failure status, number of independent power sources, number of power supply loops, number of branches in the power supply loop, node injection power, node outflow power, distributed power output, node reactive load, branch current, line loss, line resistance, line reactance, node voltage, node rated voltage and so on. and the maximum capacity of the branch; then, based on the above power data and the above time period number, with the goal of minimizing the sum of the load loss and the power outage cost, a line restoration optimization model and corresponding constraints are constructed; wherein the above constraints include: grid radial structure constraint, node active power constraint, node reactive power constraint, line voltage drop constraint, capacity constraint and voltage constraint; finally, under each of the above constraints, the above line restoration optimization model is solved to obtain the line switch state of each line when the sum of the load loss and the power outage cost is minimized, and the current distribution network is fault reconstructed according to the above line switch state. Therefore, when constructing a line restoration optimization model with the goal of minimizing the sum of the load loss and the power outage cost, the present invention takes into account the number of time periods between the current moment and the time when the fault occurs. Therefore, the calculation of the power outage cost in the obtained line restoration optimization model will change based on the change of this number of time periods, which is more in line with the actual situation, and then makes the obtained fault reconstruction result more reasonable. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings required for use in the implementation. Obviously, the drawings described below are only some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0073] Figure 1 The present invention is a flowchart of a method for fault reconstruction of a distribution network provided by an embodiment of the present invention.

[0074] Figure 2 This is a schematic diagram of user loss provided by an embodiment of the present invention.

[0075] Figure 3 It is a schematic diagram of a distribution network cost loss analysis model provided by an embodiment of the present invention.

[0076] Figure 4 This is a schematic diagram of an IEEE 802.33 node system provided by an embodiment of the present invention.

[0077] Figure 5This is a schematic diagram of the total output of a distributed power source provided by an embodiment of the present invention.

[0078] Figure 6 This is a schematic diagram of a fault reconstruction result at a first time point provided by an embodiment of the present invention.

[0079] Figure 7 This is a schematic diagram of a fault reconstruction result at a second time point provided by an embodiment of the present invention.

[0080] Figure 8 The present invention is a schematic structural diagram of a fault reconstruction device for a distribution network provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0081] To make the objectives, technical solutions, and advantages of this application more clear, the technical solutions in this application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this application.

[0082] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0083] In the description of the embodiments of this application, the technical terms "first" and "second" are used only to distinguish different objects and should not be understood to indicate or imply relative importance or implicitly specify the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0084] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0085] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0086] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0087] In the description of the embodiments of the present application, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; internal connections between two components or interactions between two components. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present application based on specific circumstances.

[0088] See also Figure 1 In order to solve the problem in the prior art that the load loss during a power outage cannot be accurately assessed due to the use of static constant load power outage loss for power grid reconstruction, resulting in an unreasonable reconstruction solution, an embodiment of the present invention provides a distribution network fault reconstruction method, comprising:

[0089] Step S101: acquiring power data during a distribution network fault, and the number of time periods between the current time and the time when the fault occurs, in real time; wherein the power data includes: node load active power, node user power outage loss cost, loss attenuation constant, load power failure status, number of independent power sources, number of power supply loops, number of branches in the power supply loops, node injection power, node outflow power, distributed power supply output, node reactive load, branch current, line loss, line resistance, line reactance, node voltage, node rated voltage, and branch maximum capacity;

[0090] Specifically, the above-mentioned load power failure state is divided into two states: complete power restoration and incomplete power restoration.

[0091] Specifically, when a distribution network failure occurs, its reconstruction and islanding strategies become particularly important. The primary goal of this fault-response phase is to rationally adjust the distribution network structure to enable the main grid to support as many power-off nodes as possible after a distribution network failure. This, along with the rational deployment of distributed power generation equipment within the distribution area, creates self-sufficient islands for load nodes that the distribution network cannot connect to due to the failure. This ensures that critical loads do not lose power, reduces outage costs for users, and ultimately improves the security and reliability of the distribution network's power supply.

[0092] Specifically, for areas with power outages and unable to connect to the main grid, once an island is formed, the power supply, previously centrally dispatched by the upper-level power grid, will be shared by distributed power sources and energy storage devices within the island. This shift requires precise calculation and balancing of power supply and demand within the island to ensure stable operation. Therefore, distribution network fault reconfiguration is more than a simple matter of load shedding and power supply reconnection; it is a complex process involving multiple aspects of the power system and requiring comprehensive consideration of numerous factors.

[0093] Step S102: Based on the power data and the time periods, and with the goal of minimizing the sum of load loss and outage cost, a line restoration optimization model and corresponding constraints are constructed; wherein the constraints include: grid radial structure constraints, node active power constraints, node reactive power constraints, line voltage drop constraints, capacity constraints, and voltage constraints;

[0094] In a preferred embodiment, the objective function of the line restoration optimization model is:

[0095]

[0096] f=min(β1f1+β2f2)

[0097] Where f1 represents the load loss, n represents the set of all nodes in the distribution network, i represents node i, ω i represents the preset load weight coefficient of node i, P L,i represents the load active power of node i, x i Indicates the load power failure state of node i. When x i = 0, indicating that the power supply of node i is fully restored. i =1, indicating that the power supply of node i has not been fully restored, f2 represents the power outage cost, C i represents the power outage loss cost of the user at the time of the fault of node i, γ represents the loss attenuation constant, t s represents the number of time periods between the current time and the time when the fault occurs, f represents the value of the objective function, β1 represents the preset weight corresponding to the load loss, and β2 represents the preset weight corresponding to the power outage cost.

[0098] Preferably, the sum of the two preset weights in the objective function is 1. In the present invention, both of the two preset weights are set to 0.5.

[0099] Specifically, the specific data for the preset load weight coefficients is determined based on the defined power load levels. Power load levels are pre-determined to be divided into three levels: primary, secondary, and tertiary, based on the importance of the node and the impact of a power outage. Primary loads are defined as nodes where a power outage would cause significant damage to human safety, economic development, and public order. For example, all load nodes critical to life safety, commercial centers in large cities, and important public venues fall under primary load. Secondary loads are defined as nodes where a power outage would cause significant damage to the social economy and public order. These load nodes are typically important load nodes such as local government departments, large and medium-sized enterprises, hospitals, and schools. Tertiary loads are defined as nodes where a power outage would not significantly impact the social economy or public order. These load nodes are typically small businesses, rural areas, and remote regions. Therefore, the power system will implement different power supply measures based on the different power load levels to ensure the reliability and safety of load nodes at each level. For example, a power outage for a primary load would cause significant social losses. Therefore, when the upper-level distribution network fails, it is necessary to ensure that the nodes corresponding to the primary load continue to be powered. Secondary and tertiary loads are allowed to experience unplanned power outages during island operation. Furthermore, for island classification, the power load level will be reflected in the node weight coefficient. For example, the power load classification table is shown in the following table:

[0100] Load importance level Grading conditions Weight coefficient 1 Power outage is not allowed under any circumstances 100 2 Minimize power outages 10 3 When the power output is insufficient, it can be cut off 1

[0101] Schematically, if node i is classified as a first-level load, its corresponding preset load weight coefficient is 100; if node i is classified as a second-level load, its corresponding preset load weight coefficient is 10; if node i is classified as a third-level load, its corresponding preset load weight coefficient is 1.

[0102] Specifically, when parts of the active distribution network operate in islanded mode, if the power supply capacity of distributed generation (DG) and energy storage systems is insufficient, some load shedding will be necessary to balance supply and demand. Priority is given to interruptible load nodes with preset load weights and minimal power outage losses. If power supply capacity remains insufficient, more critical load nodes are shelved based on the load level and the potential loss.

[0103] Schematically, the user loss diagram is as follows Figure 2As shown in the figure, generally speaking, the power outage losses of most electricity users show a nonlinear positive correlation with the power outage duration, with a large slope in the initial stage and a small slope in the later stage. The curve represents the user loss curve that changes with time, the bar graph represents the user power outage loss cost per unit time, and the change in the area of ​​the bar graph per unit time represents the above-mentioned loss attenuation constant.

[0104] Specifically, the calculation formula corresponding to the power outage cost will make the distribution network more inclined to continue supplying power to the load node with the least power loss in the previous moment during the island division process, so as to reduce the total power outage loss cost during the active distribution network failure process.

[0105] Schematically, the schematic diagram of the distribution network cost loss analysis model is as follows Figure 3 As shown, Figure 3 In the above equation, “a”, “i” and “j” all represent nodes. At node “a”, DG (distributed generation) is connected to the distribution network. Nodes i and j are the power-off nodes when a fault occurs. If the equivalent load f 1i and f 1j When they are equal, if the impact of the user power outage loss cost is ignored, both nodes may be classified as islands, which has no effect on the overall load loss. However, if the impact of the user power outage loss cost is not ignored, the user power outage loss cost loss f on the two nodes is 2i <f 2i Therefore, the power-off load on node i should be assigned to the island first, which can effectively reduce the power outage loss cost of users in the island.

[0106] Preferably, the objective function will comprehensively adjust the optimal line switch state of each line based on the number of time periods and the load power outage state, and ensure that the weight based on the power load level is not affected.

[0107] Preferably, a line restoration optimization model is constructed by using power data and time period numbers with the goal of minimizing the sum of load loss and power outage cost.

[0108] In another preferred embodiment, the radial structure of the power grid is constrained as follows:

[0109]

[0110] Where Z i,j Indicates the line switch status of the line from node i to node j. When Z i,j =1, indicating that the line switch state of the line from node i to node j is the line closed state. i,j = 0, indicating that the line switch state of the line from node i to node j is the line disconnected state, N represents the total number of nodes in the distribution network, N s Indicates the number of independent power supplies, Ml Indicates the number of branches in the power supply loop l, l represents the power supply loop l, Z (i,j),l Indicates the line switch status of the line between node i and node j in the power supply loop l;

[0111] Specifically, since the distribution network contains active equipment such as wind power, photovoltaics and energy storage, and since the distribution network fault reconstruction scheme constructed in the present invention is based on the DistFlow power flow model, the distribution network must always maintain a radial structure, and then the above-mentioned radial structure constraints of the power grid are required.

[0112] The active power constraint of the above nodes is:

[0113]

[0114] Where, represents the active power injected from node i to node j at time t, represents the active power outflow from node j at the current time t, r i,j represents the line resistance from node i to node j at time t, It represents the square term of the branch current on the branch from node i to node j at time t, represents the active power of the load of node j at time t, represents the output of distributed generation at node j at time t;

[0115] The reactive power constraint of the above nodes is:

[0116]

[0117] Where, represents the reactive power injected from node i to node j at time t, represents the reactive power outflow from node j at time t, x i,j represents the line reactance of the line from node i to node j, represents the node reactive load of node j at time t, represents the reactive power output of the distributed generation at node j at time t;

[0118] The above line voltage drop constraint is:

[0119]

[0120] Where m i,j represents a constant determined by the line switch state of the line between node i and node j, and M represents a constant with a large value. It represents the line switch state of the line from node i to node j at time t. When , it means that at time t, the line switch state of the line from node i to node j is the line closed state. When , it means that at time t, the line switch state of the line from node i to node j is the line disconnected state, represents the square term of the node voltage of node i at time t, represents the square term of the node voltage of node j at time t;

[0121] The above capacity constraints are:

[0122]

[0123] Where S max Indicates the maximum capacity of the branch;

[0124] The above voltage constraints are:

[0125]

[0126] Where y represents the allowable voltage deviation, U N Indicates the rated voltage of the node.

[0127] Specifically, in order to ensure the safe operation of the distribution network, it is necessary to construct capacity constraints and voltage constraints.

[0128] Preferably, a 0-1 variable is used to represent the line switch state, so that the feature of flexible topology transformation is more applicable during the model solution process, and the flow from the starting node to the end node in the line information is stipulated to be the positive direction. The use of the large M method can make the line voltage drop balance equation applicable to complex distribution networks with variable topologies.

[0129] In this preferred embodiment, various constraint conditions corresponding to the line restoration optimization model are constructed through power data.

[0130] Step S103: Under the above constraints, solve the line restoration optimization model to obtain the line switch status of each line when the sum of load loss and power outage cost is minimized, and reconstruct the current distribution network according to the line switch status.

[0131] Specifically, the CPlex solver is used to solve the line restoration optimization model under the above constraints, and the optimal line switching state of each line is obtained. Then, the distribution network can be reconstructed according to this switching state.

[0132] In a preferred embodiment, performing fault reconstruction on the current distribution network according to the above-mentioned line switch status includes:

[0133] Determining, based on the line switch state, a first node set on a line in a line closed state in the distribution network;

[0134] According to the first node set, power supply is restored to the nodes in the first node set in the current power distribution network.

[0135] Specifically, power supply to each node corresponding to the first node set is restored in the distribution network, thereby completing the fault reconstruction of the current distribution network.

[0136] Preferably, if the distribution network fault has not been restored after the current fault reconstruction, a new line restoration optimization model and corresponding constraints are reconstructed based on the reconstructed distribution network, and this new line restoration optimization model is re-solved. Because the objective function includes the number of time periods in the calculation formula for calculating the power outage cost, the power outage cost will change with the passage of fault time, and the new fault reconstruction results will also adaptively change with the passage of fault time. Therefore, each new fault reconstruction result is adapted to the actual current fault situation until the fault is successfully eliminated.

[0137] Schematically, the IEEE 33 node system diagram is as follows Figure 4 As shown, Figure 4 The middle dotted line is the backup contact line. Figure 4 The node importance weight classification table for each node is shown in the following table:

[0138] Node Level node Weight 1 9,3.31 100 2 16,18,27 10 3 the remaining 1

[0139] Specifically, yes Figure 4 The node cost weights for nodes 2-33 are set as [14; 18; 19; 16; 12; 9; 15; 100; 17; 13; 11; 100; 20; 8; 50; 50; 50; 7; 5; 10; 19; 6; 14; 16; 13; 50; 8; 11; 9; 100; 18; 14] (unit: 10,000 yuan). In addition, the distributed power access status is set as shown in the following table:

[0140]

[0141] Since the output of distributed power without energy storage fluctuates greatly and has poor stability, this embodiment does not use it as the supporting power source for island division. Figure 5 As shown, Figure 5"PV" in the figure represents photovoltaic power generation, and "Wind" represents wind power generation. Assume that the distribution network begins to experience a fault at 8:00 AM, a new faulty line is added at 9:00 AM, and the fault is subsequently eliminated and repaired at 10:00 AM. The faulty line table is shown below:

[0142] Failure time Fault line 8：00 6、14、19、25、32 9：00 6、14、19、21、25、32

[0143] Specifically, in order to analyze the feasibility and superiority of the fault reconstruction method of the distribution network proposed in the present invention, three comparative schemes are proposed for the above-mentioned fault conditions set in this embodiment: Scheme 1: When performing fault reconstruction, the cost factor and the load importance factor are comprehensively considered, that is, the fault reconstruction scheme proposed by the present invention. Scheme 2: When performing fault reconstruction, the cost factor is not considered, and only the load importance factor is considered. Scheme 3: When performing fault reconstruction, only the cost factor is considered, and the load importance factor is not considered. Scheme 4: When performing fault reconstruction, the cost factor and the load importance factor are comprehensively considered. However, dynamic changes are not considered in cost losses. This embodiment sets the distribution network fault period to 8:00-10:00, and sets the first time point and the second time point respectively to implement the above four schemes, wherein the first time point is 8:00, and the second time point is 9:00. The schematic diagram of the fault reconstruction result at the first time point is as shown in the figure. Figure 6 As shown, the schematic diagram of the fault reconstruction result at the second time point is as follows Figure 7 shown.

[0144] Specifically, based on the aforementioned node importance weight grading table and node cost weights, power supply to important nodes and nodes with high outage costs will be prioritized during fault reconstruction. At 8:00 AM, due to insufficient distributed energy output, node 12 was removed, and a load grading reduction program was initiated to ensure power supply quality. By 9:00 AM, after renewable energy output increased, the system stopped node removal while maintaining graded load management. After implementing the aforementioned four reconstruction schemes, the table of islanded operating nodes after reconstruction and the comparison table of reconstruction results are shown below:

[0145] Table of isolated island running nodes after reconstruction

[0146]

[0147] Reconstruction result comparison table

[0148]

[0149] Specifically, the "load priority restoration set" in the reconstruction result comparison table refers to the nodes requiring power restoration based on the line switch status results for each line obtained by solving the line restoration optimization model. As can be seen from the reconstruction result comparison table, Scheme 1 (i.e., the fault reconstruction solution of the present invention) achieved a total cost loss of 2.0773 million yuan, a 19.5% reduction compared to Scheme 2. Scheme 1 achieved a 100% restoration rate for critical loads (Level II), a 13.7% improvement compared to Scheme 3. Scheme 1 reduced economic losses by 4.8% compared to Scheme 4.

[0150] Preferably, by establishing a line restoration optimization model with time-varying characteristics, the adaptability defect of the fixed load power outage loss solution in long-term faults is effectively solved. Experimental data proves that it can reduce economic losses by 4.8%-19.5%.

[0151] Preferably, the line restoration optimization model proposed in the present invention introduces an exponential function in its objective function to quantify the variation of the load outage cost with the fault time, and combines it with the load loss amount representing the importance of the load to construct a two-dimensional (cost-importance) objective function for generating the current load priority restoration set. An objective function is established with minimizing dynamic power outage losses and maximizing power supply restoration as the core; during the entire fault period, a dynamic adjustment mechanism for the restoration strategy can be adjusted based on a rolling time window, and dynamic matching of the load priority restoration set is achieved through switch state optimization and coordinated control of distributed power output; finally, a time decay cost model is embedded in the objective function to quantify the marginal benefits of restoration operations in different time periods and optimize the switch action sequence and island power supply range.

[0152] In this preferred embodiment, the fault reconstruction of the current power distribution network is achieved by restoring power supply to the nodes that need to be closed in the line switch state.

[0153] Based on the above method embodiments, the present invention provides corresponding device embodiments.

[0154] like Figure 8 As shown, an embodiment of the present invention provides a fault reconstruction device for a distribution network, comprising:

[0155] Data acquisition module, model building module and distribution network reconstruction module;

[0156] The data acquisition module is used to obtain in real time the power data during the distribution network fault period, as well as the number of time periods between the current time and the time when the fault occurs; wherein the power data includes: node load active power, node user power outage loss cost, loss attenuation constant, load power failure status, number of independent power sources, number of power supply loops, number of branches in the power supply loop, node injection power, node outflow power, distributed power supply output, node reactive load, branch current, line loss, line resistance, line reactance, node voltage, node rated voltage, and branch maximum capacity;

[0157] The model building module is configured to construct a line restoration optimization model and corresponding constraints based on the power data and the time periods, with the goal of minimizing the sum of load loss and outage cost; wherein the constraints include: grid radial structure constraints, node active power constraints, node reactive power constraints, line voltage drop constraints, capacity constraints, and voltage constraints;

[0158] The above-mentioned distribution network reconstruction module is used to solve the above-mentioned line restoration optimization model under the above-mentioned constraints, obtain the line switch status of each line when the sum of the load loss and the power outage cost is minimized, and reconstruct the current distribution network according to the above-mentioned line switch status.

[0159] In a preferred embodiment, the objective function of the line restoration optimization model is as follows:

[0160]

[0161] f=min(β1f1+β2f2)

[0162] Where f1 represents the load loss, n represents the set of all nodes in the distribution network, i represents node i, ω i represents the preset load weight coefficient of node i, P L,i represents the load active power of node i, x i represents the load power failure state of node i, f2 represents the power outage cost, C i represents the power outage loss cost of the user at the time of the fault of node i, γ represents the loss attenuation constant, t s represents the number of time periods between the current time and the time when the fault occurs, f represents the value of the objective function, β1 represents the preset weight corresponding to the load loss, and β2 represents the preset weight corresponding to the power outage cost.

[0163] In another preferred embodiment, the radial structure of the power grid is constrained as follows:

[0164]

[0165] Where Z i,jIndicates the line switch status of the line from node i to node j. When Z i,j =1, indicating that the line switch state of the line from node i to node j is the line closed state. i,j = 0, indicating that the line switch state of the line from node i to node j is the line disconnected state, N represents the total number of nodes in the distribution network, N s Indicates the number of independent power supplies, M l Indicates the number of branches in the power supply loop l, l represents the power supply loop l, Z (i,j),l Indicates the line switch status of the line between node i and node j in the power supply loop l;

[0166] The active power constraint of the above nodes is:

[0167]

[0168] Where, represents the active power injected from node i to node j at time t, represents the active power outflow from node j at the current time t, r i,j represents the line resistance from node i to node j at time t, It represents the square term of the branch current on the branch from node i to node j at time t, represents the active power of the load of node j at time t, represents the output of distributed generation at node j at time t;

[0169] The reactive power constraint of the above nodes is:

[0170]

[0171] Where, represents the reactive power injected from node i to node j at time t, represents the reactive power outflow from node j at time t, x i,j represents the line reactance of the line from node i to node j, represents the node reactive load of node j at time t, represents the reactive power output of the distributed generation at node j at time t;

[0172] The above line voltage drop constraint is:

[0173]

[0174]

[0175] Where mi,j represents a constant determined by the line switch state of the line between node i and node j, and M represents a constant with a large value. It represents the line switch state of the line from node i to node j at time t. When , it means that at time t, the line switch state of the line from node i to node j is the line closed state. When , it means that at time t, the line switch state of the line from node i to node j is the line disconnected state, represents the square term of the node voltage of node i at time t, represents the square term of the node voltage of node j at time t;

[0176] The above capacity constraints are:

[0177]

[0178] Where S max Indicates the maximum capacity of the branch;

[0179] The above voltage constraints are:

[0180]

[0181] Where y represents the allowable voltage deviation, U N Indicates the rated voltage of the node.

[0182] In another preferred embodiment, the distribution network reconstruction module includes:

[0183] a first node set determining unit and a node power restoration unit;

[0184] The first node set determining unit is configured to determine, based on the line switch state, a first node set on a line in a line closed state in the distribution network;

[0185] The node power supply restoration unit is configured to restore power supply to nodes within the first node set in the current power distribution network based on the first node set.

[0186] It should be noted that the device embodiments described above are merely illustrative, wherein the modules described above as separate components may or may not be physically separated, and the components displayed as modules may or may not be physical modules, that is, they may be located in one place, or they may be distributed across multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the present embodiment. In addition, in the drawings of the device embodiments provided by the present invention, the connection relationship between the modules indicates that there is a communication connection between them, which can be specifically implemented as one or more communication buses or signal lines. A person of ordinary skill in the art can understand and implement the present invention without inventive work. The above schematic diagram is merely an example of a fault reconstruction device for a distribution network, and does not constitute a limitation on a fault reconstruction device for a distribution network. It may include more or fewer components than shown in the figure, or a combination of certain components, or different components.

[0187] Based on the above method embodiment, the present invention provides a corresponding terminal device embodiment.

[0188] Another embodiment of the present invention provides a terminal device, including a processor, a memory, and a computer program stored in the above-mentioned memory and configured to be executed by the above-mentioned processor. When the above-mentioned processor executes the above-mentioned computer program, it implements the above-mentioned distribution network fault reconstruction method of any embodiment of the present invention.

[0189] For example, in this embodiment, the computer program may be divided into one or more modules, which are stored in the memory and executed by the processor to implement the present invention. The one or more modules may be a series of computer program instruction segments capable of performing specific functions, which are used to describe the execution process of the computer program in the device.

[0190] The terminal device may be a computing device such as a desktop computer, a notebook computer, a PDA, or a cloud server. The device may include, but is not limited to, a processor and a memory;

[0191] The processor may be a central processing unit (CPU), other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor, etc. The processor is the control center of the above-mentioned device, connecting various parts of the entire device using various interfaces and lines;

[0192] The above-mentioned memory can be used to store the above-mentioned computer programs and / or modules. The above-mentioned processor realizes various functions of the above-mentioned device by running or executing the computer programs and / or modules stored in the above-mentioned memory, and calling the data stored in the memory. The above-mentioned memory can mainly include a program storage area and a data storage area, wherein the program storage area can store an operating system, at least one application required for a function, etc.; in addition, the memory can include a high-speed random access memory, and can also include a non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), at least one disk storage device, a flash memory device, or other volatile solid-state storage device.

[0193] Based on the above method embodiment, the present invention provides a corresponding storage medium embodiment.

[0194] Another embodiment of the present invention provides a storage medium, which includes a stored computer program, wherein when the computer program is running, the device where the storage medium is located is controlled to execute the distribution network fault reconstruction method described in any embodiment of the present invention.

[0195] In this embodiment, the storage medium is a computer-readable storage medium, and the computer program includes computer program code, which may be in source code form, object code form, an executable file, or some intermediate form. The computer-readable medium may include any entity or device capable of carrying the computer program code, a recording medium, a USB flash drive, a mobile hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunications signal, and a software distribution medium.

[0196] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for fault reconstruction of a distribution network, characterized in that: include: Real-time acquisition of power data during a distribution network fault, as well as the number of time periods between the current time and the time of the fault; wherein the power data includes: node load active power, node user power outage loss cost, loss attenuation constant, load power failure status, number of independent power sources, number of power supply loops, number of branches in the power supply loop, node injection power, node outflow power, distributed power generation output, node reactive load, branch current, line loss, line resistance, line reactance, node voltage, node rated voltage, and branch maximum capacity; Based on the power data and the number of time periods, a line restoration optimization model and corresponding constraints are constructed with the goal of minimizing the sum of load loss and outage cost; wherein the constraints include: grid radial structure constraints, node active power constraints, node reactive power constraints, line voltage drop constraints, capacity constraints, and voltage constraints; Under the constraints, the line restoration optimization model is solved to obtain the line switch status of each line when the sum of the load loss and the power outage cost is minimized, and the current distribution network is fault reconstructed according to the line switch status.

2. A distribution network fault reconstruction method according to claim 1, characterized in that: The objective function of the line restoration optimization model is: f=min(β1f1+β2f2) Where f1 represents the load loss, n represents the set of all nodes in the distribution network, i represents node i, ω i represents the preset load weight coefficient of node i, P L,i represents the load active power of node i, x i represents the load power failure state of node i, f2 represents the power outage cost, C i represents the power outage loss cost of the user at the time of the fault of node i, γ represents the loss attenuation constant, t s represents the number of time periods between the current time and the time when the fault occurs, f represents the value of the objective function, β1 represents the preset weight corresponding to the load loss, and β2 represents the preset weight corresponding to the power outage cost.

3. A distribution network fault reconstruction method according to claim 2, characterized in that: The radial structure constraints of the power grid are: Where Z i,j Indicates the line switch status of the line from node i to node j. When Z i,j =1, indicating that the line switch state of the line from node i to node j is the line closed state. i,j = 0, indicating that the line switch state of the line from node i to node j is the line disconnected state, N represents the total number of nodes in the distribution network, N s Indicates the number of independent power supplies, M l Indicates the number of branches in the power supply loop l, l represents the power supply loop l, Z (i,j),l Indicates the line switch status of the line between node i and node j in the power supply loop l; The node active power constraint is: Where, represents the active power injected from node i to node j at time t, represents the active power outflow from node j at the current time t, r i,j represents the line resistance from node i to node j at time t, It represents the square term of the branch current on the branch from node i to node j at time t, represents the active power of the load of node j at time t, represents the output of distributed generation at node j at time t; The node reactive power constraint is: Where, represents the reactive power injected from node i to node j at time t, represents the reactive power outflow from node j at time t, x i,j represents the line reactance of the line from node i to node j, represents the node reactive load of node j at time t, represents the reactive power output of the distributed generation at node j at time t; The line voltage drop constraint is: Where m i,j represents a constant determined by the line switch state of the line between node i and node j, and M represents a constant with a large value. It represents the line switch state of the line from node i to node j at time t. When , it means that at time t, the line switch state of the line between node i and node j is the line closed state. When , it means that at time t, the line switch state of the line from node i to node j is the line disconnected state, represents the square term of the node voltage of node i at time t, represents the square term of the node voltage of node j at time t; The capacity constraints are: Where S max Indicates the maximum capacity of the branch; The voltage constraint is: Where y represents the allowable voltage deviation, U N Indicates the rated voltage of the node.

4. A distribution network fault reconstruction method according to claim 3, characterized in that: Performing fault reconstruction on the current distribution network according to the line switch state includes: Determining, according to the line switch state, a first node set on a line in the distribution network that is in a line closed state; According to the first node set, power supply is restored to the nodes within the first node set in the current power distribution network.

5. A fault reconstruction device for a distribution network, characterized in that: include: Data acquisition module, model building module and distribution network reconstruction module; The data acquisition module is used to acquire power data during a distribution network fault in real time, as well as the number of time periods between the current time and the time when the fault occurs; wherein the power data includes: node load active power, node user power outage loss cost, loss attenuation constant, load power failure status, number of independent power sources, number of power supply loops, number of branches in the power supply loop, node injection power, node outflow power, distributed power supply output, node reactive load, branch current, line loss, line resistance, line reactance, node voltage, node rated voltage, and branch maximum capacity; The model building module is configured to build a line restoration optimization model and corresponding constraints based on the power data and the number of time periods, with the goal of minimizing the sum of load loss and outage cost; wherein the constraints include: grid radial structure constraints, node active power constraints, node reactive power constraints, line voltage drop constraints, capacity constraints, and voltage constraints; The distribution network reconstruction module is used to solve the line restoration optimization model under the various constraint conditions, obtain the line switch status of each line when the sum of the load loss and the power outage cost is minimized, and perform fault reconstruction on the current distribution network according to the line switch status.

6. A distribution network fault reconstruction device according to claim 5, characterized in that: The objective function of the line restoration optimization model is as follows: f=min(β1f1+β2f2) Where f1 represents the load loss, n represents the set of all nodes in the distribution network, i represents node i, ω i represents the preset load weight coefficient of node i, P L,i represents the load active power of node i, x i represents the load power failure state of node i, f2 represents the power outage cost, C i represents the power outage loss cost of the user at the time of the fault of node i, γ represents the loss attenuation constant, t s represents the number of time periods between the current time and the time when the fault occurs, f represents the value of the objective function, β1 represents the preset weight corresponding to the load loss, and β2 represents the preset weight corresponding to the power outage cost.

7. A distribution network fault reconstruction device according to claim 6, characterized in that: The radial structure constraints of the power grid are: Where Z i,j Indicates the line switch status of the line from node i to node j. When Z i,j =1, indicating that the line switch state of the line from node i to node j is the line closed state. i,j = 0, indicating that the line switch state of the line from node i to node j is the line disconnected state, N represents the total number of nodes in the distribution network, N s Indicates the number of independent power supplies, M l Indicates the number of branches in the power supply loop l, l represents the power supply loop l, Z (i,j),l Indicates the line switch status of the line between node i and node j in the power supply loop l; The node active power constraint is: Where, represents the active power injected from node i to node j at time t, represents the active power outflow from node j at the current moment, r i,j represents the line resistance from node i to node j at time t, It represents the square term of the branch current on the branch from node i to node j at time t, represents the active power of the load of node j at time t, represents the output of distributed generation at node j at time t; The node reactive power constraint is: Where, represents the reactive power injected from node i to node j at time t, represents the reactive power outflow from node j at time t, x i,j represents the line reactance of the line from node i to node j, represents the node reactive load of node j at time t, represents the reactive power output of the distributed generation at node j at time t; The line voltage drop constraint is: Where m i,j represents a constant determined by the line switch state of the line between node i and node j, and M represents a constant with a large value. It represents the line switch state of the line from node i to node j at time t. When , it means that at time t, the line switch state of the line from node i to node j is the line closed state. When , it means that at time t, the line switch state of the line from node i to node j is the line disconnected state, represents the square term of the node voltage of node i at time t, represents the square term of the node voltage of node j at time t; The capacity constraints are: Where S max Indicates the maximum capacity of the branch; The voltage constraint is: Where y represents the allowable voltage deviation, U N Indicates the rated voltage of the node.

8. The fault reconstruction device for a distribution network according to claim 7, characterized in that: The distribution network reconstruction module includes: a first node set determining unit and a node power restoration unit; The first node set determining unit is configured to determine, according to the line switch state, a first node set on a line in the distribution network that is in a line closed state; The node power supply restoration unit is configured to restore power supply to nodes within the first node set in the current power distribution network based on the first node set.

9. A terminal device, characterized in that: The method comprises a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein when the processor executes the computer program, the method for fault reconstruction of a distribution network according to any one of claims 1 to 4 is implemented.

10. A storage medium, characterized in that: The storage medium includes a stored computer program, wherein when the computer program is running, the device where the storage medium is located is controlled to execute the fault reconstruction method of the distribution network according to any one of claims 1 to 4.

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