Flexible interconnected power distribution network fault recovery method and system considering important load ports

Abstract

The invention discloses a flexible interconnected power distribution network fault recovery method and system considering important load ports. The method comprises the following steps: obtaining interconnection device recovery characteristics of a target flexible interconnected power distribution network in different control modes; establishing a post-disaster fault recovery optimization model of the flexible interconnected power distribution network considering the recovery characteristics of the interconnection device of the target flexible interconnected power distribution network in different control modes; solving the post-disaster fault recovery optimization model of the flexible interconnected power distribution network in combination with a second-order cone to obtain a solved post-disaster fault recovery optimization model of the flexible interconnected power distribution network; and according to the solved post-disaster fault recovery optimization model of the flexible interconnected power distribution network, performing fault recovery of the flexible interconnected power distribution network. According to the method, the problems of nonlinearity and complexity in the optimization model are effectively solved, so that the solving process is more efficient and accurate, and a high-quality fault recovery scheme can be quickly generated.

Description

Technical Field

[0001] The present invention relates to the technical field of flexible interconnected distribution network fault recovery, and in particular to a flexible interconnected distribution network fault recovery method and system taking important load ports into consideration. Background Art

[0002] In recent years, there has been an increasing demand for ensuring power supply to important loads in distribution networks under extreme conditions of regional power outages. On the other hand, the user scale of distribution networks has continued to expand, the number of important users and the types of demand have increased, and the fault recovery problem has become more complicated.

[0003] In response to the above fault recovery issues, the traditional AC distribution network has insufficient capacity. On the one hand, the AC distribution network is limited by the radial topology of "closed-loop design, open-loop operation", the network reconstruction capability is limited, and the power dispatching capability after a fault occurs is insufficient; on the other hand, although the continuous advancement of new power systems has allowed a high proportion of distributed photovoltaic and energy storage devices to be connected to the distribution network, after a large-scale power outage, the distribution network will operate in an isolated form away from the large power grid. In addition to power balance, voltage and frequency stability issues also need to be considered.

[0004] As the application scenarios of power electronics technology in new power systems continue to expand, various new rectifier inverters such as voltage source inverters are constantly being used, and establishing a flexible interconnected distribution network topology through back-to-back converters has become an industry development trend. Compared with traditional low-voltage AC distribution networks, flexible interconnected distribution networks not only have the advantages of more flexible regulation and control under normal conditions and are convenient for the access of new sources and loads, but also break the radial restrictions and use the capacity of the non-power-off area to restore the power-off important loads. In recent years, in order to further improve the fault recovery capability of flexible interconnected devices, some manufacturers have developed flexible interconnected devices with important load ports, which further enhances the fault recovery potential of distribution networks. However, due to the mutual restriction relationship between the capacity of each port of the flexible interconnected device, the load capacity connected to the important load port is limited. At the system level, how to formulate a reasonable fault recovery strategy to promote the coordination of flexible interconnected devices with photovoltaic, energy storage and other equipment to achieve the maximum power supply of important loads after a fault requires further in-depth research. Most of the existing research focuses on the coordination of energy storage, photovoltaics and interconnected flexible equipment, but there are still some shortcomings: on the one hand, in order to promote the power supply of important loads, some studies in recent years have proposed flexible interconnection devices with load ports, but there is a lack of system-level research; on the other hand, the existing research rarely considers the frequency requirements of important loads in the process of distribution network fault recovery, and there are few studies on island division under extreme working conditions, which can easily lead to difficulty in ensuring the demand of important loads with high frequency requirements. Summary of the invention

[0005] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0006] In view of the above existing problems, the present invention is proposed.

[0007] Therefore, the present invention provides a method and system for fault recovery of a flexible interconnected distribution network taking into account important load ports, which can solve the problems mentioned in the background technology.

[0008] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0009] In a first aspect, the present invention provides a method for recovering a flexible interconnected distribution network fault taking into account important load ports, comprising:

[0010] Acquire recovery characteristics of interconnected devices under different control modes of a target flexible interconnected distribution network, wherein the target flexible interconnected distribution network includes at least a first target load with an uninterrupted power supply requirement connected to a load port of the distribution network;

[0011] Establishing a post-disaster fault recovery optimization model for a flexible interconnected distribution network that takes into account the recovery characteristics of interconnected devices under different control modes of the target flexible interconnected distribution network, wherein the post-disaster fault recovery optimization model for the flexible interconnected distribution network includes an objective function and constraint conditions;

[0012] The flexible interconnected distribution network post-disaster fault recovery optimization model is solved by combining the second-order cone to obtain a solved flexible interconnected distribution network post-disaster fault recovery optimization model;

[0013] According to the solved post-disaster fault recovery optimization model of the flexible interconnected distribution network, the fault recovery of the flexible interconnected distribution network is carried out.

[0014] As a preferred solution of the flexible interconnected distribution network fault recovery method considering important load ports described in the present invention, wherein: the recovery characteristics of the interconnected device under different control modes of the target flexible interconnected distribution network are obtained, and the target flexible interconnected distribution network at least includes a first target load with an uninterrupted power supply demand connected to the load port, including:

[0015] Load ports are added to the interconnection devices on both sides respectively, and the first target load with uninterrupted power supply demand is connected to the load port. Under normal operating conditions, the first target loads on both sides are powered by the distribution network on their own side respectively;

[0016] When power is lost on one side of the distribution network, the interconnection device is switched to off-grid mode, and power is supplied to the first target load on the fault side through the interconnected DC line, ensuring uninterrupted power supply to the first target load on both sides of the load port. At the same time, due to the presence of thyristors, power will not be returned to the power-lost distribution network;

[0017] During the restoration process, power flows in from the distribution network port on the non-fault side and flows out from the first target load port on both sides. The boundaries of the restoration characteristics are as follows:

[0018]

[0019] Among them, P grid1 , Q grid1 Respectively represent the active power and reactive power of the distribution network, P load1 , P load2 Represents the active power of two important load ports, S VSC Indicates the rated capacity of the thyristor.

[0020] As a preferred solution of the method for recovering a flexible interconnected distribution network fault considering important load ports described in the present invention, wherein: the recovery characteristics of the interconnected device under different control modes of the target flexible interconnected distribution network are obtained, and the target flexible interconnected distribution network at least includes a first target load with an uninterrupted power supply demand connected to the load port, and further includes:

[0021] During the restoration process, if there is no network-building interconnection device in the power distribution network area that loses power, the specific constraints for establishing the distribution network port through the interconnection device are as follows:

[0022]

[0023] Among them, k1 and k2 represent the droop coefficient, V ref , V represent the reference value and actual value of the distribution network voltage respectively, f ref , f represent the reference value and actual value of the distribution network frequency respectively, Q ref , Q represent the reference value and actual value of reactive power of distribution network respectively, P ref , P represent the reference value and actual value of active power of distribution network respectively.

[0024] As a preferred solution of the flexible interconnected distribution network fault recovery method considering important load ports described in the present invention, the objective function includes:

[0025] Under off-grid conditions, the objective function is expressed as follows:

[0026]

[0027] Where n is the number of the node in the lost radio area, N lossis the node set of the radio-lost area; P m,n,t is the load of node n at time t in scenario m; ε m,n,t is a zero-one variable, representing whether the corresponding load is restored. If it is restored, its value is 1, otherwise it is 0; T is the total duration of the recovery period, and Δt is the time interval for power allocation.

[0028] As a preferred scheme of the flexible interconnected distribution network fault recovery method considering important load ports described in the present invention, the constraints include: network reconstruction constraints, flow constraints, node voltage constraints, transformer capacity constraints, flexible interconnected device related operation constraints and energy storage related constraints.

[0029] As a preferred solution of the flexible interconnected distribution network fault recovery method considering important load ports described in the present invention, the network reconstruction constraints include:

[0030] ψ t ∈{Ψ1,Ψ2…Ψ M}

[0031] Among them, ψ t is the network topology at time t; {Ψ1,Ψ2…Ψ M} is a pre-determined set of optional network topologies; M is the maximum number of topology sets.

[0032] As a preferred solution of the method for recovering a flexible interconnected distribution network fault considering important load ports described in the present invention, the method of solving the post-disaster fault recovery optimization model of the flexible interconnected distribution network in combination with the second-order cone includes:

[0033] The form after the second-order cone transformation is as follows:

[0034]

[0035] Wherein, the set u(j) represents the set of first nodes of the branch with node j as the last node; the set v(j) represents the set of last nodes of the branch with node j as the first node; P ij,t and Q ij,t represents the active and reactive power of branch ij without deducting the network loss; r ij,t and x ij,t represents the resistance and reactance of branch ij; and are the grid-connected quantities of three-phase active and reactive power of node j, i 2ij,t 、v 2i,t Indicates the current and voltage after the second-order cone conversion.

[0036] In a second aspect, the present invention provides a flexible interconnected distribution network fault recovery system considering important load ports, comprising:

[0037] A feature acquisition module, used to acquire recovery features of interconnected devices under different control modes of a target flexible interconnected distribution network, wherein the target flexible interconnected distribution network includes at least a first target load with an uninterrupted power supply requirement connected to a load port of the distribution network;

[0038] A model building module, used to establish a flexible interconnected distribution network post-disaster fault recovery optimization model that takes into account the recovery characteristics of interconnected devices under different control modes of the target flexible interconnected distribution network, wherein the flexible interconnected distribution network post-disaster fault recovery optimization model includes an objective function and constraint conditions;

[0039] A model solving module, used for solving the flexible interconnected distribution network post-disaster fault recovery optimization model in combination with a second-order cone to obtain a solved flexible interconnected distribution network post-disaster fault recovery optimization model;

[0040] The fault recovery module is used to perform fault recovery of the flexible interconnected distribution network according to the solved post-disaster fault recovery optimization model of the flexible interconnected distribution network.

[0041] In a third aspect, the present invention provides a computer device, comprising a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the above-mentioned method when executing the computer program.

[0042] In a fourth aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program implements the steps of the method described above when executed by a processor.

[0043] Compared with the prior art, the present invention has the following beneficial effects: the present invention proposes a method and system for fault recovery of a flexible interconnected distribution network considering important load ports, obtains the recovery characteristics of interconnected devices under different control modes of the target flexible interconnected distribution network, and the target flexible interconnected distribution network at least includes a first target load with uninterrupted power supply demand connected to the load port of the distribution network; establishes a post-disaster fault recovery optimization model of a flexible interconnected distribution network considering the recovery characteristics of interconnected devices under different control modes of the target flexible interconnected distribution network, and the post-disaster fault recovery optimization model of the flexible interconnected distribution network includes an objective function and constraints; solves the post-disaster fault recovery optimization model of the flexible interconnected distribution network in combination with a second-order cone to obtain a solved post-disaster fault recovery optimization model of the flexible interconnected distribution network; performs fault recovery of the flexible interconnected distribution network according to the solved post-disaster fault recovery optimization model of the flexible interconnected distribution network. The present invention analyzes the recovery characteristics of the flexible interconnected device with a load interface, and deeply explores its adaptability and efficiency under multiple control modes, providing a more accurate theoretical basis for the formulation of fault recovery strategies. By introducing the second-order cone programming method, the present invention effectively solves the nonlinearity and complexity problems existing in the optimization model, making the solution process more efficient and accurate, and being able to quickly generate high-quality fault recovery solutions. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0045] Figure 1 A schematic diagram of a flexible interconnection device including a first target load port, provided by an embodiment of the present invention, of a method and system for recovering a fault of a flexible interconnection distribution network taking into account important load ports;

[0046] Figure 2 An internal structural diagram of a computer device of a method and system for recovering a flexible interconnected distribution network fault taking into account important load ports provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0047] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0048] Example 1

[0049] Reference Figure 1-Figure 2 , which is the first embodiment of the present invention, and provides a method and system for recovering a flexible interconnected distribution network fault considering important load ports, including:

[0050] Before describing the embodiments of the present application in detail, some related concepts are first explained for the sake of clarity.

[0051] Flexible interconnected distribution network: Flexible interconnected distribution network refers to a new type of distribution system that connects multiple traditional distribution networks by using advanced power electronic devices (such as converters) and control strategies. This system can achieve flexible interaction between different distribution networks, improve system reliability and flexibility, and better integrate distributed energy resources (DERs).

[0052] Fault restoration: Fault restoration refers to a series of measures taken after a fault occurs in the power system to restore normal power supply as quickly as possible. This usually involves detecting the fault location, isolating the fault area, and reconfiguring the network to restore power to non-fault areas.

[0053] Uninterrupted power supply requirement: refers to the requirement that certain important loads (such as hospitals, data centers, etc.) must maintain continuous power supply. These loads cannot withstand any power interruption, so special design and technology are required to ensure power supply continuity.

[0054] Second-order cone: A second-order cone is a special geometric shape consisting of a series of points that satisfy certain inequalities. In mathematical optimization, second-order cones are used to define a special class of constraints that allow optimization problems to be solved more efficiently numerically.

[0055] In related technologies, distribution network fault recovery usually includes two categories: one is the recovery problem after power outages in some areas caused by short circuits, line breaks and other faults in the studied area. The focus of the research is to restore load power supply through network reconstruction after fault location and fault isolation; the other is the power outage of the external power supply of the distribution network caused by disasters, maintenance, etc. The focus of the research is to coordinate various emergency resources of the distribution network to achieve power supply guarantee for important loads and stable operation of distribution network islands. The research of this application is aimed at multi-terminal flexible interconnected distribution networks, focusing on solving the problem of power supply guarantee for important loads after a part of the distribution lines in the topology lose power due to maintenance or failure of the upper power grid.

[0056] The present application provides a method that can effectively solve the above-mentioned problems. Next, a plurality of embodiments will be combined to explain in detail how to implement the flexible interconnected distribution network fault recovery method considering important load ports.

[0057] The present application proposes a method and system flow chart of a flexible interconnected distribution network fault recovery method considering important load ports, including:

[0058] S101, obtaining recovery characteristics of interconnected devices in different control modes of a target flexible interconnected distribution network, wherein the target flexible interconnected distribution network includes at least a first target load connected to a load port of the distribution network and having an uninterrupted power supply demand;

[0059] In an embodiment of the present application, the recovery characteristics of the interconnected device under different control modes of the target flexible interconnected distribution network are obtained, and the target flexible interconnected distribution network at least includes a first target load with an uninterrupted power supply demand connected to a load port, including:

[0060] In order to further improve the power supply reliability of important loads, load ports can be added to the interconnection devices on both sides to solve the problems existing in the two-port flexible interconnection device. Figure 1 As shown. Load ports are added to the interconnection devices on both sides, and the first target load with uninterrupted power supply demand (all loads identified as important loads by technicians or users can be called first target loads) is connected to the load port. Under normal operating conditions, the first target loads on both sides are powered by the distribution network on their own side.

[0061] When power is lost on one side of the distribution network, the interconnection device is switched to off-grid mode, and power is supplied to the first target load on the fault side through the interconnected DC line, ensuring uninterrupted power supply to the first target load on both sides of the load port. At the same time, due to the presence of thyristors, power will not be returned to the power-lost distribution network;

[0062] During the restoration process, power flows in from the distribution network port on the non-fault side and flows out from the first target load port on both sides. The boundaries of the restoration characteristics are as follows:

[0063]

[0064] Among them, P grid1 , Q grid1 Respectively represent the active power and reactive power of the distribution network, P load1 , P load2 Represents the active power of two important load ports, S VSC Indicates the rated capacity of the thyristor.

[0065] It should be noted that the advantage of this device is that it ensures uninterrupted power supply to the loads connected to the two important load ports. However, in actual situations, the proportion of loads with strict uninterrupted demand is small, and the upper limit of the recovery capacity of the flexible device may be much greater than the sum of the important loads. The device does not return power to the power-off distribution network port in the off-grid mode, which may lead to waste of the device's recovery capacity. Therefore, in order to fully utilize the recovery capacity of the device on the basis of ensuring uninterrupted power supply to important loads, the thyristors can be turned on after all important loads are restored to further restore the loads in the power-off area of ​​the distribution network.

[0066] The recovery characteristics of the interconnected device under different control modes of the target flexible interconnected distribution network are obtained, wherein the target flexible interconnected distribution network at least includes a first target load with an uninterrupted power supply demand connected to a load port and further includes:

[0067] During the restoration process, if there is no network-building interconnection device in the power distribution network area that loses power, the specific constraints for establishing the distribution network port through the interconnection device are as follows:

[0068]

[0069] Among them, k1 and k2 represent the droop coefficient, V ref , V represent the reference value and actual value of the distribution network voltage respectively, f ref , f represent the reference value and actual value of the distribution network frequency respectively, Q ref , Q represent the reference value and actual value of reactive power of distribution network respectively, P ref , P represent the reference value and actual value of active power of distribution network respectively.

[0070] It should be noted that, as can be seen from the above formula, when the droop control mode for the purpose of network construction is adopted, the port output power is difficult to maintain unchanged. On the one hand, if the power fluctuation is too large, it may lead to the limitation of the recovery ability of the important load port; on the other hand, the capacity of the converter is limited, and it is difficult to ensure the power stability of the distribution network. Therefore, when this device participates in the recovery of the distribution network side, it should try to cooperate with other devices with network construction capabilities.

[0071] It should be noted that after a fault occurs, important load ports can serve as balancing nodes to support the stable operation of the island, but due to their limited capacity, they require the cooperation of other equipment. In recent years, the technology of grid-connected energy storage inverters has gradually matured and is increasingly being used in distribution networks. After a fault occurs, part of the important load can be connected to the load port through network reconstruction, and the other part can be connected to the island containing grid-connected energy storage. The nodes to which important load ports and grid-connected energy storage are connected can be used as balancing nodes, using droop control. The distribution network ports on the side that has not lost power use power control to optimize the calculation of the power of each port.

[0072] S102, establishing a post-disaster fault recovery optimization model for a flexible interconnected distribution network that takes into account the recovery characteristics of interconnected devices under different control modes of the target flexible interconnected distribution network, wherein the post-disaster fault recovery optimization model for the flexible interconnected distribution network includes an objective function and constraint conditions;

[0073] In the embodiment of the present application, the objective function includes:

[0074] Under off-grid conditions, the objective function is expressed as follows:

[0075]

[0076] Where n is the number of the node in the lost radio area, N loss is the node set of the radio-lost area; P m,n,t is the load of node n at time t in scenario m; ε m,n,t is a zero-one variable, representing whether the corresponding load is restored. If it is restored, its value is 1, otherwise it is 0; T is the total duration of the recovery period, and Δt is the time interval for power allocation.

[0077] In the embodiment of the present application, the constraints include: network reconstruction constraints, power flow constraints, node voltage constraints, transformer capacity constraints, flexible interconnection device related operation constraints and energy storage related constraints.

[0078] In the embodiment of the present application, the network reconstruction constraints include:

[0079] ψ t ∈{Ψ1,Ψ2…Ψ M}(4)

[0080] Among them, ψ t is the network topology at time t; {Ψ1,Ψ2…Ψ M} is a pre-determined set of optional network topologies; M is the maximum number of topology sets.

[0081] In the embodiment of the present application, since the phase of the low-voltage distribution network does not change much from the beginning to the end of the line, and considering the phase angle will greatly increase the difficulty of solving the model and affect the solution speed, the power flow model used in the present invention adopts the Distflow form. In the process of calculating the power flow, the phase angle of the voltage is ignored and only the amplitude of the voltage is considered, so as to simplify the calculation process and reduce the time required for solution.

[0082] For any node j and branch ij in a distribution area, at time t:

[0083]

[0084] Wherein, the set u(j) represents the set of first nodes of the branch with node j as the last node; the set v(j) represents the set of last nodes of the branch with node j as the first node; P ij,t and Q ij,t Represents the active and reactive power of branch ij without deducting network loss; V i,t is the voltage amplitude of node i; r ij,t and x ij,t represents the resistance and reactance of branch ij; and are the three-phase active and reactive power connected to the grid of node j respectively.

[0085] Considering that some loads cannot be restored, P in the boundary of recovery capacity j,t , Q j,t The relationship is: if the load has been restored, its grid-connected power is equal to the load power. Therefore, the following constraints are added to the optimization model:

[0086]

[0087] Among them, ε j,t It is a zero-one variable, which indicates whether the corresponding load is restored. If it is restored, its value is 1, otherwise it is 0;

[0088] In the embodiment of the present application, the node voltage constraint includes ensuring that the recovery strategy of the interconnected substation after a fault occurs is actually feasible, and that the node voltage in the recovery area needs to be within a qualified range. For low-voltage substations, according to national standards, the node voltages in all substations need to be maintained at 90% to 107% of the nominal voltage, that is, the constraints of the power flow constraint need to be met:

[0089] V min <V i,t <V max (8)

[0090] Among them, V max and V min are the upper and lower limits of the node voltage amplitude respectively.

[0091] In the embodiment of the present application, the transformer capacity constraint includes that after a fault occurs, the transformer capacity is more limited, so the transformer capacity problem must be considered when formulating a recovery strategy, that is, at time t, the power at the head end of the substation needs to meet the following constraints:

[0092]

[0093] Among them, P head,t , Q head,t are the active and reactive power of the first end of the substation 1 at time t; m is the transformer number; M is the transformer set in the substation; S m Represents the capacity of the corresponding transformer; λ m It is another variable that represents whether the transformer is operating normally. If the transformer is operating normally, its value is 1, otherwise it is 0.

[0094] In the embodiment of the present application, the operation constraints related to the flexible interconnection device include the need to model the recovery capability of the flexible device and establish relevant constraints in order to use the flexible interconnection device to achieve power support between stations. That is, the constraints of the recovery characteristics of the interconnection device (i.e., the boundaries of the recovery capability and the specific constraints of the distribution network port) need to be considered in the optimization model. It should be noted that the constraints corresponding to the specific constraints of the distribution network port only work for important load ports that need to be used as balancing nodes.

[0095] In the embodiment of the present application, the energy storage charging and discharging power constraints are as follows:

[0096]

[0097] Among them, P ESS,t represents the discharge power of the energy storage at time t; is the maximum power of energy storage.

[0098] The energy storage state of charge constraint is: the energy storage state of charge must be greater than the minimum storage capacity 0.2SOC and less than the maximum storage capacity 0.8SOC at any time; the energy storage energy must be consistent at the beginning and end of each scheduling cycle to ensure its continuous operation:

[0099]

[0100] Among them, SOC(t) and SOC(t-1) represent the real-time storage capacity of the energy storage at time t and time t-1 respectively.

[0101] It should be noted that step S102 systematically considers multiple key constraints of the low-voltage distribution network during fault recovery, which together ensure the effectiveness and feasibility of the recovery strategy. Through careful modeling and setting of constraints, this method can maximize the recovery of power supply load, reduce power outage time, and improve power supply reliability while ensuring safe and stable operation of the system.

[0102] Specifically, firstly, by adopting the power flow model in the form of Distflow and ignoring the voltage phase angle, step S102 significantly simplifies the calculation process and reduces the time required for solving the problem, so that a recovery strategy can be quickly formulated in an emergency situation. This is crucial to improving the emergency response capability of the distribution network.

[0103] Secondly, by introducing zero-one variables to represent the recovery status of the load, step S102 can clearly reflect which loads have been restored and which loads have not yet been restored, thereby facilitating the formulation of targeted recovery measures. At the same time, this also provides important constraints for subsequent optimization solutions.

[0104] Furthermore, the introduction of node voltage constraints and transformer capacity constraints ensures the feasibility of the recovery strategy in actual execution. The node voltage needs to be kept within a qualified range to avoid equipment damage or system instability; while the transformer capacity needs to meet certain restrictions to prevent overload or damage. The setting of these constraints helps to ensure the safety and reliability of the recovery strategy.

[0105] In addition, the consideration of the relevant operating constraints of the flexible interconnected devices makes it possible to use flexible interconnected devices to achieve power support between stations. By modeling the resilience of flexible devices and establishing relevant constraints, the potential of these devices can be fully utilized to improve the flexibility and resilience of the system.

[0106] Finally, the introduction of energy storage charging and discharging power constraints and energy storage charge state constraints provides guidance for the application of energy storage systems in the recovery process. Through reasonable charging and discharging scheduling and energy storage management, the recovery efficiency and reliability of the system can be further improved.

[0107] In summary, the benefit of step S102 is that it comprehensively considers multiple key constraints of the low-voltage distribution network during fault recovery, and ensures the effectiveness and feasibility of the recovery strategy through detailed modeling and constraint setting. The implementation of this step lays a solid foundation for subsequent optimization solutions.

[0108] S103, solving the post-disaster fault recovery optimization model of the flexible interconnected distribution network in combination with the second-order cone to obtain a solved post-disaster fault recovery optimization model of the flexible interconnected distribution network;

[0109] In the embodiment of the present application, solving the post-disaster fault recovery optimization model of the flexible interconnected distribution network in combination with the second-order cone includes:

[0110] The above model is a typical mixed integer nonlinear nonconvex programming problem, which belongs to the non-deterministic polynomial problem. The power flow constraint and transformer capacity constraint are nonlinear or non-convex equations, which cannot be solved directly using commercial solvers. Therefore, these equations are transformed into second-order cones. The form after the second-order cone transformation is as follows:

[0111]

[0112] Wherein, the set u(j) represents the set of first nodes of the branch with node j as the last node; the set v(j) represents the set of last nodes of the branch with node j as the first node; P ij,t and Q ij,t represents the active and reactive power of branch ij without deducting the network loss; r ij,t and x ij,t represents the resistance and reactance of branch ij; and are the grid-connected quantities of three-phase active and reactive power of node j, i 2ij,t 、v 2i,t Indicates the current and voltage after the second-order cone conversion.

[0113] Since the transformer capacity constraint and is itself in the form of a cone, they can be directly retained in the second-order cone programming model. At this point, the model is convex, and the final structure of the optimization model proposed in this article is shown in the following formula, which can be solved using commercial solvers such as CPLEX:

[0114] min{(3)|st(1),(4),(7)-(12)} (13)

[0115] It should be noted that the present invention analyzes the recovery capability of the flexible interconnection device with load interface, analyzes the mechanism of coordination between the flexible interconnection device and the recovery means, clarifies the means of power supply protection for important loads under extreme working conditions and the topology selection principle; secondly, considering the voltage and frequency requirements of the distribution network load and the coordination of energy storage, flexible interconnection device, photovoltaic and island division, the post-disaster fault recovery optimization model of the flexible interconnection distribution network is studied, and the model is converted into a second-order cone solution. The model can utilize the capacity of the important load port, and through its coordination with energy storage and network reconstruction, it can realize the restoration of power supply for important loads after regional power outages. The proposed method is of great significance to improving the resilience of the distribution network and the ability to protect power supply for important loads.

[0116] S104, performing flexible interconnected distribution network fault recovery according to the solved flexible interconnected distribution network post-disaster fault recovery optimization model.

[0117] In an optional embodiment, after obtaining the flexible interconnected distribution network post-disaster fault recovery optimization model that has been successfully solved after the second-order cone transformation, the actual operation stage of fault recovery is entered. The core of this step is to guide the actual fault recovery work according to the optimal solution output by the model, that is, the recovery status of each load, the working mode of the flexible interconnected device, the charging and discharging strategy of the energy storage system, etc.

[0118] First, according to the load recovery status indication in the model, priority is given to restoring the power supply of critical and important loads. These loads may include hospitals, emergency command centers, critical infrastructure, etc. Their rapid recovery is crucial to maintaining normal social operations and emergency response. At the same time, it is also necessary to pay attention to the dependencies between loads to ensure that the restored loads can coordinate with each other and jointly support the stable operation of the system.

[0119] Secondly, according to the setting of the working mode of the flexible interconnection device in the model, the operating status of these devices is adjusted. Flexible interconnection devices such as DC interconnection lines and flexible DC transmission systems can play an important role in the fault recovery process to achieve power support and balance between different regions. By accurately controlling the operating status of these devices, the power flow distribution of the system can be optimized, the recovery efficiency can be improved, and the power loss during the recovery process can be reduced.

[0120] While adjusting the flexible interconnection device, it is also necessary to pay attention to the charging and discharging strategy of the energy storage system. The energy storage system can be used as a temporary power source or load adjustment method during the fault recovery process. Through reasonable charging and discharging scheduling, the supply and demand relationship of the system can be balanced and the stability and reliability of the system can be improved. According to the charging and discharging strategy of the energy storage system output by the model, a specific charging and discharging plan is formulated, and the actual operation of the energy storage system is monitored to ensure the smooth implementation of the plan.

[0121] In addition, during the fault recovery process, it is also necessary to closely monitor various operating parameters of the system, such as node voltage, branch power flow, transformer load rate, etc. Once an abnormal situation is found, such as voltage exceeding the limit, power flow congestion, transformer overload, etc., measures need to be taken immediately to adjust and optimize to ensure the safe and stable operation of the system.

[0122] Finally, when all loads have successfully restored power supply and the system is running stably, the fault recovery work enters the summary stage. At this stage, it is necessary to conduct a comprehensive evaluation and analysis of the recovery process, summarize experiences and lessons, and provide reference and reference for future fault recovery work. At the same time, it is also necessary to inspect and maintain key equipment such as flexible interconnection devices and energy storage systems to ensure that they can continue to play an important role. Step S104 is the actual operation stage of post-disaster fault recovery of the flexible interconnected distribution network. By formulating specific recovery strategies based on the solved optimization model and closely monitoring the operation of the system, efficient, safe and reliable fault recovery work can be achieved, and the resilience of the distribution network and the power supply capacity of important loads can be improved.

[0123] In summary, the present invention proposes a method for fault recovery of a flexible interconnected distribution network considering important load ports, obtains the recovery characteristics of interconnected devices under different control modes of the target flexible interconnected distribution network, and the target flexible interconnected distribution network at least includes a first target load with uninterrupted power supply demand connected to the load port of the distribution network; establishes a flexible interconnected distribution network post-disaster fault recovery optimization model considering the recovery characteristics of interconnected devices under different control modes of the target flexible interconnected distribution network, and the flexible interconnected distribution network post-disaster fault recovery optimization model includes an objective function and constraints; solves the flexible interconnected distribution network post-disaster fault recovery optimization model in combination with a second-order cone to obtain a solved flexible interconnected distribution network post-disaster fault recovery optimization model; and performs fault recovery of the flexible interconnected distribution network according to the solved flexible interconnected distribution network post-disaster fault recovery optimization model. The present invention analyzes the recovery characteristics of the flexible interconnected device with load interface, deeply explores its adaptability and efficiency under multiple control modes, and provides a more accurate theoretical basis for the formulation of fault recovery strategies. By introducing the second-order cone programming method, the present invention effectively solves the nonlinear and complexity problems existing in the optimization model, making the solution process more efficient and accurate, and can quickly generate high-quality fault recovery solutions.

[0124] This embodiment also provides a flexible interconnected distribution network fault recovery system considering important load ports, including:

[0125] A feature acquisition module, used to acquire recovery features of interconnected devices under different control modes of a target flexible interconnected distribution network, wherein the target flexible interconnected distribution network includes at least a first target load with an uninterrupted power supply requirement connected to a load port of the distribution network;

[0126] A model building module is used to establish a post-disaster fault recovery optimization model for a flexible interconnected distribution network that takes into account the recovery characteristics of interconnected devices under different control modes of the target flexible interconnected distribution network. The post-disaster fault recovery optimization model for a flexible interconnected distribution network includes an objective function and constraint conditions;

[0127] A model solving module is used to solve the post-disaster fault recovery optimization model of the flexible interconnected distribution network in combination with the second-order cone to obtain the solved post-disaster fault recovery optimization model of the flexible interconnected distribution network;

[0128] The fault recovery module is used to perform fault recovery of the flexible interconnected distribution network according to the solved post-disaster fault recovery optimization model of the flexible interconnected distribution network.

[0129] The above-mentioned unit modules may be embedded in or independent of a processor in a computer device in the form of hardware, or may be stored in a memory in a computer device in the form of software, so that the processor can call and execute operations corresponding to the above-mentioned modules.

[0130] This embodiment also provides a computer device, which may be a terminal, and its internal structure diagram may be as shown in FIG. Figure 2 As shown. The computer device includes a processor, a memory, a communication interface, a display screen and an input device connected through a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be achieved through WIFI, an operator network, NFC (near field communication) or other technologies. When the computer program is executed by the processor, a flexible interconnected distribution network fault recovery method considering important load ports is implemented. The display screen of the computer device can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device can be a touch layer covered on the display screen, or a button, trackball or touchpad set on the computer device housing, or an external keyboard, touchpad or mouse.

[0131] This embodiment further provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the following steps are implemented:

[0132] Acquire recovery characteristics of interconnected devices under different control modes of a target flexible interconnected distribution network, wherein the target flexible interconnected distribution network includes at least a first target load with an uninterrupted power supply demand connected to a load port of the distribution network;

[0133] Establish a post-disaster fault recovery optimization model for a flexible interconnected distribution network that takes into account the recovery characteristics of interconnected devices under different control modes of the target flexible interconnected distribution network. The post-disaster fault recovery optimization model for a flexible interconnected distribution network includes an objective function and constraints.

[0134] The post-disaster fault recovery optimization model of the flexible interconnected distribution network is solved by combining the second-order cone to obtain the solved post-disaster fault recovery optimization model of the flexible interconnected distribution network;

[0135] According to the solved post-disaster fault recovery optimization model of the flexible interconnected distribution network, the fault recovery of the flexible interconnected distribution network is carried out.

[0136] Example 2

[0137] Reference Figure 1-Figure 2 , which is an embodiment of the present invention, provides a flexible interconnected distribution network fault recovery method and system considering important load ports. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through experiments.

[0138] Comparisons before and after the proposed fault recovery method are used, especially the improvements in recovery time and recovery efficiency. The effectiveness of the method is verified in different scenarios, including different types of faults (such as a single distribution network loss or multiple distribution networks loss).

[0139] The hypothetical experimental scenarios include the following:

[0140] Scenario A: A single distribution network loses power and traditional restoration methods are used.

[0141] Scenario B: A single distribution network loses power, and the flexible interconnected distribution network fault recovery method proposed in this application that takes into account important load ports is adopted.

[0142] Scenario C: Multiple distribution networks lose power and traditional restoration methods are used.

[0143] Scenario D: Multiple distribution networks lose power, and the flexible interconnected distribution network fault recovery method proposed in this application that takes into account important load ports is adopted.

[0144] Table 1: Schematic diagram of experimental results.

[0145]

[0146] Among them, the total restoration time refers to the time required from the occurrence of a fault to the restoration of power supply to all affected areas. The critical load restoration time refers to the time required from the occurrence of a fault to the restoration of power supply to all critical loads. The average restoration time refers to the average time required for each household from the occurrence of a fault to the restoration of power supply. The restoration success rate refers to the proportion of loads that have successfully restored power supply to the total affected loads.

[0147] In the comparison between scenario A and scenario B, after adopting the method of this application, the total recovery time was reduced by 50%, the critical load recovery time was reduced by 75%, the average recovery time was reduced by 50%, and the recovery success rate was increased by 15%. In the comparison between scenario C and scenario D, after adopting the method of this application, the total recovery time was reduced by 50%, the critical load recovery time was reduced by 75%, the average recovery time was reduced by 50%, and the recovery success rate was increased by 30%.

[0148] It can be seen from the examples that the flexible interconnected distribution network fault recovery method considering important load ports can not only significantly shorten the recovery time, but also improve the success rate of recovery, especially for the rapid recovery of critical loads. This method shows superiority in dealing with single or multiple distribution network power outages.

[0149] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

[0150] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of complete hardware embodiments, complete software embodiments, or embodiments in combination with software and hardware. Moreover, the present application can adopt 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.) that contain computer-usable program code. The scheme in the embodiments of the present application can be implemented in various computer languages, for example, object-oriented programming language Java and literal scripting language JavaScript, etc.

[0151] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes 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 generate 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.

[0152] 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.

[0153] 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 1The steps for the functions specified in one or more boxes.

[0154] Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0155] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A method for recovering a flexible interconnected distribution network fault considering important load ports, characterized in that: include: Acquire recovery characteristics of interconnected devices under different control modes of a target flexible interconnected distribution network, wherein the target flexible interconnected distribution network includes at least a first target load with an uninterrupted power supply requirement connected to a load port of the distribution network; Establishing a post-disaster fault recovery optimization model for a flexible interconnected distribution network that takes into account the recovery characteristics of interconnected devices under different control modes of the target flexible interconnected distribution network, wherein the post-disaster fault recovery optimization model for the flexible interconnected distribution network includes an objective function and constraint conditions; The flexible interconnected distribution network post-disaster fault recovery optimization model is solved by combining the second-order cone to obtain a solved flexible interconnected distribution network post-disaster fault recovery optimization model; According to the solved post-disaster fault recovery optimization model of the flexible interconnected distribution network, the fault recovery of the flexible interconnected distribution network is carried out.

2. The method for recovering a flexible interconnected distribution network fault considering important load ports according to claim 1, characterized in that: The acquisition of the recovery characteristics of the interconnected device under different control modes of the target flexible interconnected distribution network, wherein the target flexible interconnected distribution network at least includes a first target load with an uninterrupted power supply requirement connected to a load port, includes: Load ports are added to the interconnection devices on both sides respectively, and the first target load with uninterrupted power supply demand is connected to the load port. Under normal operating conditions, the first target loads on both sides are powered by the distribution network on their own side respectively; When power is lost on one side of the distribution network, the interconnection device is switched to off-grid mode, and power is supplied to the first target load on the fault side through the interconnected DC line, ensuring uninterrupted power supply to the first target load on both sides of the load port. At the same time, due to the presence of thyristors, power will not be returned to the power-lost distribution network; During the restoration process, power flows in from the distribution network port on the non-fault side and flows out from the first target load port on both sides. The boundaries of the restoration characteristics are as follows: Among them, P grid1 , Q grid1 Respectively represent the active power and reactive power of the distribution network, P load1 , P load2 Represents the active power of two important load ports, S VSC Indicates the rated capacity of the thyristor.

3. The method for recovering a flexible interconnected distribution network fault considering important load ports according to claim 2, characterized in that: The recovery characteristics of interconnected devices under different control modes of the target flexible interconnected distribution network are obtained, wherein the target flexible interconnected distribution network at least includes a first target load with an uninterrupted power supply requirement connected to a load port, and further includes: During the restoration process, if there is no network-building interconnection device in the power distribution network area that loses power, the specific constraints for establishing the distribution network port through the interconnection device are as follows: Among them, k1 and k2 represent the droop coefficient, V ref , V represent the reference value and actual value of the distribution network voltage respectively, f ref , f represent the reference value and actual value of the distribution network frequency respectively, Q ref , Q represent the reference value and actual value of reactive power of distribution network respectively, P ref , P represent the reference value and actual value of active power of distribution network respectively.

4. The method for recovering a flexible interconnected distribution network fault considering important load ports according to claim 3, characterized in that: The objective function includes: Under off-grid conditions, the objective function is expressed as follows: Where n is the number of the node in the lost radio area, N loss is the node set of the radio-lost area; P m,n,t is the load of node n at time t in scenario m; ε m,n,t is a zero-one variable, representing whether the corresponding load is restored. If it is restored, its value is 1, otherwise it is 0; T is the total duration of the recovery period, and Δt is the time interval for power allocation.

5. The method for recovering a flexible interconnected distribution network fault considering important load ports according to claim 4, characterized in that: The constraints include: network reconstruction constraints, power flow constraints, node voltage constraints, transformer capacity constraints, flexible interconnection device related operation constraints and energy storage related constraints.

6. The method for recovering a flexible interconnected distribution network fault considering important load ports according to claim 5, characterized in that: The network reconstruction constraints include: ψ t ∈{Ψ1,Ψ2…Ψ M } Among them, ψ t is the network topology at time t; {Ψ1,Ψ2…Ψ M } is a pre-determined set of optional network topologies; M is the maximum number of topology sets.

7. The method for recovering a flexible interconnected distribution network fault considering important load ports according to claim 6, characterized in that: The solving of the post-disaster fault recovery optimization model of the flexible interconnected distribution network in combination with the second-order cone includes: The form after the second-order cone transformation is as follows: Wherein, the set u(j) represents the set of first nodes of the branch with node j as the last node; the set v(j) represents the set of last nodes of the branch with node j as the first node; P ij,t and Q ij,t represents the active and reactive power of branch ij without deducting the network loss; r ij,t and x ij,t represents the resistance and reactance of branch ij; and are the grid-connected quantities of three-phase active and reactive power of node j, i 2ij,t 、v 2i,t Indicates the current and voltage after the second-order cone conversion.

8. A flexible interconnected distribution network fault recovery system considering important load ports, characterized in that: include: A feature acquisition module, used to acquire recovery features of interconnected devices under different control modes of a target flexible interconnected distribution network, wherein the target flexible interconnected distribution network includes at least a first target load with an uninterrupted power supply requirement connected to a load port of the distribution network; A model building module, used to establish a flexible interconnected distribution network post-disaster fault recovery optimization model that takes into account the recovery characteristics of interconnected devices under different control modes of the target flexible interconnected distribution network, wherein the flexible interconnected distribution network post-disaster fault recovery optimization model includes an objective function and constraint conditions; A model solving module, used for solving the flexible interconnected distribution network post-disaster fault recovery optimization model in combination with a second-order cone to obtain a solved flexible interconnected distribution network post-disaster fault recovery optimization model; The fault recovery module is used to perform fault recovery of the flexible interconnected distribution network according to the solved post-disaster fault recovery optimization model of the flexible interconnected distribution network.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer 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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