Power distribution network fault recovery method and device considering photovoltaic grid-connected and off-grid

Abstract

The invention discloses a power distribution network fault recovery method and device considering photovoltaic grid-connected and off-grid, and the method comprises the steps: building a fault isolation model after a fault occurs based on a virtual fault flow in a fault isolation stage; obtaining circuit breaker actions according to the fault isolation model so as to isolate faults; in the network reconstruction stage, constructing a network reconstruction model after fault isolation based on the virtual fault flow; obtaining a switching action according to the network reconstruction model so as to reconstruct a network; taking the fault isolation model and the network reconstruction model as basic models, taking the maximum total power loss load recovery amount as a target, and establishing a power distribution network fault recovery model considering photovoltaic grid-connected and off-grid; solving the power distribution network fault recovery model to obtain a fault recovery result; according to the method, the influence of photovoltaic grid-connected and off-grid control in the fault recovery process of the power distribution network is considered, and the fault recovery effect of the power distribution network is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of distribution network control, and in particular to a distribution network fault recovery method and device considering photovoltaic grid-connected and off-grid. Background Art

[0002] In recent years, with the continuous increase in the scale of new energy access, the volatility of the net load of the distribution network has increased, causing the distribution network to face problems such as source-load timing mismatch and tight flexibility. Therefore, it is of great significance to study the fault recovery strategy of the distribution network considering the access of new energy to ensure the continuous power supply of important loads, which is of great significance to the improvement of the safety and economy of the distribution network. However, in the current distribution network fault recovery model considering photovoltaic access, the control of photovoltaic grid connection and off-grid is rarely considered, which is different from the actual operation of the distribution network, resulting in unsatisfactory effect of distribution network fault recovery. Summary of the invention

[0003] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a distribution network fault recovery method and device taking into account photovoltaic grid-connected and off-grid control, taking into account the influence of photovoltaic grid-connected and off-grid control in the distribution network fault recovery process, the distribution network fault recovery effect is better, and it is of great significance to improve the safety and economy of the distribution network.

[0004] To achieve the above object, the present invention is implemented by adopting the following technical solutions: In a first aspect, the present invention provides a distribution network fault recovery method considering photovoltaic grid-connected and off-grid connected, comprising: In the fault isolation stage, a fault isolation model is constructed based on the virtual fault power flow after the fault occurs; Obtaining circuit breaker action according to the fault isolation model to isolate the fault; In the network reconstruction phase, a network reconstruction model after fault isolation is constructed based on virtual fault flow; Acquire a switch action according to the network reconstruction model to reconstruct the network; Taking the fault isolation model and the network reconstruction model as the basic model and maximizing the total power-off load recovery amount as the goal, a distribution network fault recovery model considering photovoltaic grid connection and off-grid operation is established; Solving the distribution network fault recovery model to obtain a fault recovery result; Wherein, the consideration of photovoltaic grid-connected and off-grid includes: In the first fault recovery period, it is considered that all photovoltaics on the nodes affected by the fault are off-grid, and the photovoltaic output of each node is not counted; From the second fault recovery period to the final fault recovery period, the photovoltaic power generation on the nodes restored by network reconstruction is considered to be grid-connected, and the nodes restored by network reconstruction are included in the photovoltaic output.

[0005] Optionally, the fault isolation model is: ; ; ; ; ; ; ; ; ; In the formula, Fault isolation phase branch Virtual fault flow; For branch Middle node Side and back nodes The state of the switch on the side in the normal operation scenario, is a very large number, For Node , branch road and nodes On the branch road The corresponding virtual power flow variables after a fault occurs, Rely on nodes A branch circuit assembly with switches on one side and circuit breakers on the other. Rely on nodes A branch circuit assembly equipped with switches on one side and circuit breakers on the other; For branch Middle node Side and back nodes The circuit breaker on the branch line Status after a failure occurs; is the substation node set and the load node set, For Node Branch The status affected by the fault.

[0006] Optionally, the network reconstruction model is: ; ; ; ; ; ; ; ; ; ; In the formula, Reconstruction phase branch for the network Virtual fault flow; For branch Middle node Side and back nodes The switch on the branch The state after a failure occurs, is a very large number, For Node , branch road and nodes The corresponding virtual power flow variables after network reconstruction are: Rely on nodes Side and back nodes A branch collection equipped with switches on the side; is the substation node set and the load node set, For Node Branch The state affected by the fault, For Node In the recovery state after network reconstruction, For Node During the failure recovery period The active power and reactive power of For Node During the failure recovery period The active power demand and reactive power demand of A collection of failure recovery periods.

[0007] Optionally, the constraints considered for photovoltaic grid-connected and off-grid connected systems include: Constraints for the first failure recovery period: ; Constraints from the second failure recovery period to the final failure recovery period; ; Power flow constraints: ; ; ; ; In the formula, is a very large number, For branch Middle node Side and back nodes The switch on the side is in the fault recovery period status, is a branch set, For branch During the failure recovery period By Node Flow to Node The active power and reactive power of is a set of failure recovery time periods; Node voltage constraints: ; ; In the formula, are the lower and upper limits of the node voltage, For Node and nodes During the failure recovery period The voltage, Reconstruct the branch line for the network The disconnected state, For branch resistance and reactance; Branch capacity constraints: ; ; ; In the formula, For branch Maximum transmission power; Node power balance constraints: ; ; In the formula, For the node Adjacent but not on the node The set of nodes on the path to the root node, For branch During the failure recovery period By Node Flow to Node The active power and reactive power of For Node During the failure recovery period of reactive power.

[0008] Optionally, the distribution network fault recovery model is: ; In the formula, is the total power-off load recovery amount, For Node During the failure recovery period The recovery state and active power, For Node The weight coefficient of is a set of failure recovery periods, is the set of load nodes.

[0009] Optionally, the constraints of the distribution network fault recovery model include: Radial topology constraints: ; ; In the formula, For branch Middle node Side and back nodes The switch on the side is in the fault recovery period status, For branch During the failure recovery period The disconnected state, For Node During the failure recovery period The recovery state, A collection of branches.

[0010] Optionally, the solution of the distribution network fault recovery model includes: The distribution network fault recovery model is equivalently converted into a mixed integer linear programming model, and the mixed integer linear programming model is solved by using a branch and bound method.

[0011] In a second aspect, the present invention provides a distribution network fault recovery device considering photovoltaic grid-connected and off-grid, the device comprising: A fault isolation processing module is used to construct a fault isolation model after a fault occurs based on a virtual fault flow during the fault isolation phase; and obtain a circuit breaker action according to the fault isolation model to isolate the fault; A network reconstruction processing module is used to construct a network reconstruction model after fault isolation based on a virtual fault flow during the network reconstruction phase; and obtain a switch action according to the network reconstruction model to reconstruct the network; A fault recovery processing module is used to establish a distribution network fault recovery model considering photovoltaic grid connection and off-grid operation based on the fault isolation model and the network reconstruction model as the basic model and with the maximum total power loss load recovery as the goal; solve the distribution network fault recovery model to obtain a fault recovery result; Wherein, the consideration of photovoltaic grid-connected and off-grid includes: In the first fault recovery period, it is considered that all photovoltaics on the nodes affected by the fault are off-grid, and the photovoltaic output of each node is not counted; From the second fault recovery period to the final fault recovery period, the photovoltaic power generation on the nodes restored by network reconstruction is considered to be grid-connected, and the nodes restored by network reconstruction are included in the photovoltaic output.

[0012] In a third aspect, the present invention provides an electronic device, including a processor and a storage medium; The storage medium is used to store instructions; The processor is used to operate according to the instructions to execute the steps according to the above method.

[0013] In a fourth aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, which implements the steps of the above method when executed by a processor.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a distribution network fault recovery method and device considering photovoltaic grid-connected and off-grid control, taking into account the influence of photovoltaic grid-connected and off-grid control in the distribution network fault recovery process, and defaults to all photovoltaics on nodes affected by the fault at the initial moment being off-grid, and then taking into account the photovoltaic power on the restored nodes after network reconstruction, which is more in line with the actual operation of the distribution network; thereby improving the distribution network fault recovery effect, which is of great significance to the improvement of the safety and economy of the distribution network. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a flow chart of a distribution network fault recovery method considering photovoltaic grid-connected and off-grid provided by an embodiment of the present invention; Figure 2 It is a structural diagram of an IEEE 33-node test system provided by an embodiment of the present invention; Figure 3 It is a schematic diagram of a distribution network fault recovery process of an IEEE 33-node test system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0016] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0017] Embodiment 1:

[0018] like Figure 1 As shown, an embodiment of the present invention provides a distribution network fault recovery method considering photovoltaic grid-connected and off-grid, comprising the following steps: Step S1: In the fault isolation stage, a fault isolation model after a fault occurs is constructed based on a virtual fault flow; a circuit breaker action is obtained according to the fault isolation model to isolate the fault; Before the fault branch is isolated, the circuit breaker cuts off the fault current by the following actions: When the virtual fault power flows through a branch or bus, if the branch or bus is affected by the fault, the corresponding virtual power flow variable is equal to 0; if the network is running normally, the corresponding virtual power flow variable is equal to 1; if the virtual fault power flow comes from the fault branch xy ; The fault current propagates along the connection path. xy When a fault occurs, if the branch ij of i end or j A switch is installed at the end. ij Affected by the fault, that is, when the branch virtual fault flow is 0, the node side switch will operate to isolate the fault. ij If there is no circuit breaker or switch installed at one end of the branch, the virtual fault flow of the node at that end is always equal to the virtual fault flow of the branch. The above actions form a fault isolation model: ; ; ; ; ; ; ; ; ; In the formula, Fault isolation phase branch Virtual fault flow; For branch Middle node Side and back nodes The state of the switch on the side in the normal operation scenario, is a very large number, For Node , branch road and nodes On the branch road The corresponding virtual power flow variables after a fault occurs, Rely on nodes A branch circuit assembly with switches on one side and circuit breakers on the other. Rely on nodes A branch circuit assembly equipped with switches on one side and circuit breakers on the other; For branch Middle node Side and back nodes The circuit breaker on the branch line Status after a failure occurs; is the substation node set and the load node set, For Node Branch The status affected by the fault.

[0019] Step S2: In the network reconstruction phase, a network reconstruction model after fault isolation is constructed based on the virtual fault flow; a switch action is obtained according to the network reconstruction model to reconstruct the network; Network reconstruction by opening / closing switches to restore as much of the outage load as possible, including: After the network is reconfigured, the isolated part of the network is represented by another virtual power flow variable; if the virtual fault flow flows through a branch or node, if the branch or node is isolated, the corresponding virtual power flow variable is equal to 0, and if the branch or node belongs to another part of the network, the corresponding virtual power flow variable is equal to 1. The above actions form a network reconstruction model: ; ; ; ; ; ; ; ; ; ; In the formula, Reconstruction phase branch for the network Virtual fault flow; For branch Middle node Side and back nodes The switch on the branch The state after a failure occurs, is a very large number, For Node , branch road and nodes The corresponding virtual power flow variables after network reconstruction are: Rely on nodes Side and back nodes A branch collection equipped with switches on the side; is the substation node set and the load node set, For Node Branch The state affected by the fault, For Node In the recovery state after network reconstruction, For Node During the failure recovery period The active power and reactive power of For Node During the failure recovery period The active power demand and reactive power demand of A collection of failure recovery periods.

[0020] Step S3: Taking the fault isolation model and the network reconstruction model as the basic model and maximizing the total power loss load recovery as the goal, a distribution network fault recovery model considering photovoltaic grid connection and off-grid operation is established; solving the distribution network fault recovery model to obtain the fault recovery result.

[0021] Wherein, the consideration of photovoltaic grid-connected and off-grid includes: In the first fault recovery period, it is considered that all photovoltaics on the nodes affected by the fault are off-grid, and the photovoltaic output of each node is not counted; From the second fault recovery period to the final fault recovery period, the photovoltaic power generation on the nodes restored by network reconstruction is considered to be grid-connected, and the nodes restored by network reconstruction are included in the photovoltaic output.

[0022] Considering the photovoltaic grid-connected and off-grid conditions, the distribution network fault recovery is iteratively solved: The default conditions in the iteration are as follows: in each round of iteration, for nodes that have not been restored, the photovoltaic power is completely ignored in the subsequent time period; the time scale of photovoltaic grid connection and disconnection is set to be consistent with the time scale of load power and photovoltaic power; in each round of iteration, the reconstructed topology needs to meet the power supply capacity constraints of subsequent time periods; the branch switches that have been closed before the constraint must be closed in the subsequent time period, that is, the restored nodes will not be powered off again.

[0023] The first round of iteration: In the initial period after the fault occurs, it is assumed that all photovoltaics on the nodes affected by the fault are disconnected from the grid, and the established distribution network fault recovery model is used to perform fault isolation and the first network reconstruction.

[0024] Second round of iteration: Starting from the second period after the fault occurs, for the nodes whose power supply has been restored after reconstruction, the power of photovoltaic power is taken into account, the node injection power is corrected, and the distribution network fault recovery model established is used for the second network reconstruction.

[0025] The third and subsequent iterations: In each iteration, the steps of the second iteration are repeated for the nodes that have been restored to power after the previous iteration until all loads are restored to power or all iterations of the fault recovery period are completed, and the iterative solution is completed.

[0026] At the first moment after the fault, it is considered that all photovoltaics on the nodes affected by the fault are offline, and the network is reconstructed; starting from the second moment, for the restored nodes, the power of photovoltaics is taken into account and the node injection power is corrected; for the load transfer stage, the power supply capacity constraints in each time period under the topological state after the transfer need to be met.

[0027] Constraints include; Constraints for the first failover window: ; Constraints from the second failure recovery period to the final failure recovery period: ; In the formula, For Node During the failure recovery period The injected power and active power, For Node During the failure recovery period The photovoltaic output For Node Recovery state after network reconstruction; is a set of failure recovery periods, is the set of load nodes; Power flow constraints: ; ; ; ; In the formula, is a very large number, For branch Middle node Side and back nodes The switch on the side is in the fault recovery period status, is a branch set, For branch During the failure recovery period By Node Flow to Node The active power and reactive power of is a set of failure recovery time periods; Node voltage constraints: ; ; In the formula, are the lower and upper limits of the node voltage, For Node and nodes During the failure recovery period The voltage, Reconstruct the branch line for the network The disconnected state, For branch resistance and reactance; Branch capacity constraints: ; ; ; In the formula, For branch Maximum transmission power; Node power balance constraints: ; ; In the formula, For the node Adjacent but not on the node The set of nodes on the path to the root node, For branch During the failure recovery period By Node Flow to Node The active power and reactive power of For Node During the failure recovery period of reactive power.

[0028] Based on the aforementioned virtual fault power flow model, it is suggested to consider the distribution network fault recovery model of photovoltaic grid-connected and off-grid. The constraints include all the aforementioned constraints, and the objective function is to maximize the total power loss load recovery: ; In the formula, is the total power-off load recovery amount, For Node During the failure recovery period The recovery state and active power, For Node The weight coefficient of is a set of failure recovery periods, is the set of load nodes.

[0029] The constraints of the distribution network fault recovery model include: Radial topology constraints: ; ; In the formula, For branch Middle node Side and back nodes The switch on the side is in the fault recovery period status, For branch During the failure recovery period The disconnected state, For Node During the failure recovery period The recovery state, A collection of branches.

[0030] The solution of the distribution network fault recovery model includes: The distribution network fault restoration model is equivalently transformed into a mixed integer linear programming model, and the mixed integer linear programming model is solved by the branch and bound method.

[0031] Based on the above embodiment, a distribution network fault recovery method considering photovoltaic grid-connected and off-grid is applied and analyzed as follows: The IEEE 33-node test system is used in this embodiment. Figure 2 As shown, the system includes 33 nodes and 37 lines, of which there are 5 tie lines. To analyze the feasibility of the distribution network fault recovery model of this embodiment, this embodiment sets all photovoltaic nodes affected by the fault to be disconnected from the grid, performs network reconstruction, and then counts the photovoltaic power of the nodes that have been restored after network reconstruction and corrects the node injection power. Three load weight coefficients of 0.1, 1, and 10 are assigned to each load node respectively. The load weight distribution is shown in Table 1, and the photovoltaic power connected to each node is shown in Table 2.

[0032] Table 1 Load weight coefficient of each node

[0033] Table 2 Photovoltaic power connected to each node (unit: 10MW)

[0034] In this embodiment, it is assumed that branch 5-6 fails and there are 6 failure recovery periods. The topology recovery result is as follows: Figure 3 The total power-off load recovery amount is shown in Table 3.

[0035] Table 3 Total power failure load recovery

[0036] Depend on Figure 3 It can be seen that in the initial period after the fault, due to the photovoltaic off-grid and insufficient power supply capacity of the power grid, the power supply of 21 nodes was restored, and there were still 12 nodes that had not been restored. Among the nodes connected to the photovoltaic, nodes 8, 11, 14, 20, 23, 25, and 29 have been restored to power. The photovoltaic power will be counted in the second round of iteration, and the node injection power will be corrected for the second round of network reconstruction iteration. In the second round, 5 new nodes were restored to power, among which the nodes connected to the photovoltaic were nodes 26 and 30. Their photovoltaic power will be counted in the third round of iteration, and the node injection power will be corrected for the third round of iteration. In the third round of iteration, 5 new nodes were restored to power, and in the fifth round of iteration, 1 new node was restored to power.

[0037] In summary, as the photovoltaic power plants connected to the load nodes gradually resume grid-connected operation, the power supply capacity of the network is improved, and the power supply to each load node is gradually restored, which verifies the effectiveness of the present invention.

[0038] Embodiment 2: An embodiment of the present invention provides a distribution network fault recovery device considering photovoltaic grid-connection and off-grid connection, the device comprising: The fault isolation processing module is used to construct a fault isolation model after the fault occurs based on the virtual fault flow during the fault isolation phase; obtain the circuit breaker action according to the fault isolation model to isolate the fault; The network reconstruction processing module is used to construct a network reconstruction model after fault isolation based on the virtual fault flow during the network reconstruction phase; obtain the switch action according to the network reconstruction model to reconstruct the network; The fault recovery processing module is used to establish a distribution network fault recovery model considering photovoltaic grid connection and off-grid operation based on the fault isolation model and the network reconstruction model, with the goal of maximizing the total power loss load recovery; solve the distribution network fault recovery model to obtain the fault recovery result; Wherein, the consideration of photovoltaic grid-connected and off-grid includes: In the first fault recovery period, it is considered that all photovoltaics on the nodes affected by the fault are off-grid, and the photovoltaic output of each node is not counted; From the second fault recovery period to the final fault recovery period, the photovoltaic power generation on the nodes restored by network reconstruction is considered to be grid-connected, and the nodes restored by network reconstruction are included in the photovoltaic output.

[0039] Embodiment three:

[0040] Based on the first embodiment, the embodiment of the present invention provides an electronic device, including a processor and a storage medium; The storage medium is used to store instructions; The processor is used to operate according to the instructions to execute the steps according to the above method.

[0041] Embodiment 4:

[0042] Based on the first embodiment, the embodiment of the present invention provides a computer-readable storage medium, on which a computer program is stored, and when the program is executed by a processor, the steps of the above method are implemented.

[0043] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0044] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0045] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0046] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0047] The above is only 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 technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A distribution network fault recovery method considering photovoltaic grid-connected and off-grid, characterized in that: include: In the fault isolation stage, a fault isolation model is constructed based on the virtual fault power flow after the fault occurs; Obtaining circuit breaker action according to the fault isolation model to isolate the fault; In the network reconstruction phase, a network reconstruction model after fault isolation is constructed based on virtual fault flow; Acquire a switch action according to the network reconstruction model to reconstruct the network; Taking the fault isolation model and the network reconstruction model as the basic model and maximizing the total power-off load recovery amount as the goal, a distribution network fault recovery model considering photovoltaic grid connection and off-grid operation is established; Solving the distribution network fault recovery model to obtain a fault recovery result; Wherein, the consideration of photovoltaic grid-connected and off-grid includes: In the first fault recovery period, it is considered that all photovoltaics on the nodes affected by the fault are off-grid, and the photovoltaic output of each node is not counted; From the second fault recovery period to the final fault recovery period, the photovoltaic power generation on the nodes restored by network reconstruction is considered to be grid-connected, and the nodes restored by network reconstruction are included in the photovoltaic output.

2. The distribution network fault recovery method considering photovoltaic grid-connected and off-grid according to claim 1 is characterized in that: The fault isolation model is: ； ； ； ； ； ； ； ； ； In the formula, Fault isolation phase branch Virtual fault flow; For branch Middle node Side and back nodes The state of the switch on the side in the normal operation scenario, is a very large number, For Node , branch road and nodes On the branch road The corresponding virtual power flow variables after a fault occurs, Rely on nodes A branch circuit assembly with switches on one side and circuit breakers on the other. Rely on nodes A branch circuit assembly equipped with switches on one side and circuit breakers on the other; For branch Middle node Side and back nodes The circuit breaker on the branch line Status after a failure occurs; is the substation node set and the load node set, For Node Branch The status affected by the fault.

3. The distribution network fault recovery method considering photovoltaic grid-connected and off-grid according to claim 1, characterized in that: The network reconstruction model is: ； ； ； ； ； ； ； ； ； ； In the formula, Reconstruction phase branch for the network Virtual fault flow; For branch Middle node Side and back nodes The switch on the branch The state after a failure occurs, is a very large number, For Node , branch road and nodes The corresponding virtual power flow variables after network reconstruction are: Rely on nodes Side and back nodes A branch collection equipped with switches on the side; is the substation node set and the load node set, For Node Branch The state affected by the fault, For Node In the recovery state after network reconstruction, For Node During the failure recovery period The active power and reactive power of For Node During the failover period The active power demand and reactive power demand of A collection of failure recovery periods.

4. The distribution network fault recovery method considering photovoltaic grid-connected and off-grid according to claim 1, characterized in that: The constraints for considering photovoltaic grid-connected and off-grid connection include: Constraints for the first failure recovery period: ； Constraints from the second failure recovery period to the final failure recovery period; ； In the formula, For Node During the failover period The injected power and active power, For Node During the failover period The photovoltaic output For Node Recovery state after network reconstruction; is a set of failure recovery periods, is the set of load nodes; Power flow constraints: ； ； ； ； In the formula, is a very large number, For branch Middle node Side and back nodes The switch on the side is in the fault recovery period status, is a branch set, For branch During the failover period By Node Flow to Node The active power and reactive power of is a set of failure recovery time periods; Node voltage constraints: ； ； In the formula, are the lower and upper limits of the node voltage, For Node and nodes During the failover period The voltage, Reconstruct the branch line for the network The disconnected state, For branch resistance and reactance; Branch capacity constraints: ； ； ； In the formula, For branch Maximum transmission power; Node power balance constraints: ； ； In the formula, For the node Adjacent but not on the node The set of nodes on the path to the root node, For branch During the failover period By Node Flow to Node The active power and reactive power of For Node During the failover period of reactive power.

5. The distribution network fault recovery method considering photovoltaic grid-connected and off-grid according to claim 1, characterized in that: The distribution network fault recovery model is: ； In the formula, is the total power-off load recovery amount, For Node During the failover period The recovery state and active power, For Node The weight coefficient of is a set of failure recovery periods, is the set of load nodes.

6. The distribution network fault recovery method considering photovoltaic grid-connected and off-grid according to claim 5 is characterized in that: The constraints of the distribution network fault recovery model include: Radial topology constraints: ； ； In the formula, For branch Middle node Side and back nodes The switch on the side is in the fault recovery period status, For branch During the failover period The disconnected state, For Node During the failover period The recovery state, A collection of branches.

7. The distribution network fault recovery method considering photovoltaic grid-connected and off-grid according to claim 5, characterized in that: The solution of the distribution network fault recovery model includes: The distribution network fault recovery model is equivalently converted into a mixed integer linear programming model, and the mixed integer linear programming model is solved by using a branch and bound method.

8. A distribution network fault recovery device considering photovoltaic grid-connected and off-grid, characterized in that: The device comprises: A fault isolation processing module is used to construct a fault isolation model after a fault occurs based on a virtual fault flow during the fault isolation phase; and obtain a circuit breaker action according to the fault isolation model to isolate the fault; A network reconstruction processing module is used to construct a network reconstruction model after fault isolation based on a virtual fault flow during the network reconstruction phase; and obtain a switch action according to the network reconstruction model to reconstruct the network; A fault recovery processing module is used to establish a distribution network fault recovery model considering photovoltaic grid connection and off-grid operation based on the fault isolation model and the network reconstruction model as the basic model and with the maximum total power loss load recovery as the goal; solve the distribution network fault recovery model to obtain a fault recovery result; Wherein, the consideration of photovoltaic grid-connected and off-grid includes: In the first fault recovery period, it is considered that all photovoltaics on the nodes affected by the fault are off-grid, and the photovoltaic output of each node is not counted; From the second fault recovery period to the final fault recovery period, the photovoltaic power generation on the nodes restored by network reconstruction is considered to be grid-connected, and the nodes restored by network reconstruction are included in the photovoltaic output.

9. An electronic device, characterized in that: including processor and storage medium; The storage medium is used to store instructions; The processor is configured to operate according to the instructions to execute the steps of the method according to any one of claims 1-7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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