Method and system for improving toughness of power distribution network based on reinforcement and enhancement redundancy, and medium

Abstract

The invention relates to a power distribution network toughness improvement method and system based on reinforcement and redundancy enhancement and a medium, and the method comprises the steps: respectively calculating line operation failure probabilities obtained by employing different line toughness enhancement strategies for a target line in a power distribution network, comprehensively considering the cost constraint of the line toughness enhancement and the load loss value caused by the line fault, and selecting the optimal line toughness enhancement strategy to reinforce the target line; energy storage equipment configuration is carried out on the power distribution network, and after the energy storage equipment configuration cost and the energy storage configuration constraint are comprehensively considered, an optimal energy storage equipment configuration scheme is obtained to carry out enhanced redundancy configuration on the power distribution network. Compared with the prior art, the method has the advantages that the toughness of the power distribution network can be effectively and reliably improved, and the cost can be optimized.

Description

Technical Field

[0001] The present invention relates to the field of distribution network structure adjustment, and in particular to a method, system and medium for improving the resilience of a distribution network based on reinforcement and enhanced redundancy. Background Art

[0002] With the rapid development of smart grid technology, the continuous upgrade of distribution automation, the large-scale access of distributed energy, and the continuous progress of microgrid technology, the distribution network has more flexible means to improve resilience. There are mainly four core means to improve the resilience of the distribution network: planning methods for improving resilience, disaster prevention measures, rapid response and recovery capabilities, and coupling analysis and management. For example, the invention with the application number CN202410765123.8 and the publication number CN118333410A discloses a method, system, device and medium for analyzing, determining and preventing the risk transmission of the power grid, realizing the accurate identification of the risk transmission path and key nodes of the power grid system, improving the dimension and efficiency of risk transmission analysis, and enhancing the resilience and security of the power grid.

[0003] Among them, the measures to improve the resilience of the distribution network are shown in Table 1.

[0004] Table 1 Resilience Improvement Measures

[0005]

[0006]

[0007] As can be seen from Table 1, there are a variety of measures that can be taken to improve the resilience of the distribution network, which directly or indirectly improve resilience from different angles and aspects. Therefore, when making decisions, many factors such as economic investment issues, the necessity of measures or the problems brought about need to be weighed at the same time. For example, in the planning method for improving resilience, the measure of selectively using underground cables instead of overhead lines. Compared with overhead lines, underground cables not only have a high cost, but also have a complex maintenance process. Therefore, power grid companies need to consider many factors and optimize investment. This measure can be taken in areas with high reliability requirements, large impact from weather or frequent weather changes. Summary of the Invention

[0008] The purpose of the present invention is to overcome the above-mentioned defects existing in the prior art, and provide a method, system and medium for improving the resilience of a distribution network based on reinforcement and enhanced redundancy, so as to achieve effective and reliable resilience improvement and cost optimization.

[0009] The purpose of the present invention can be achieved by the following technical solutions:

[0010] A method for improving the resilience of a distribution network based on reinforcement and enhanced redundancy, comprising the following steps:

[0011] Calculate the line operation failure probabilities of the target lines in the distribution network obtained by adopting different line resilience enhancement strategies respectively, and comprehensively consider the cost constraint of line resilience enhancement and the value of load loss caused by line faults, and select the optimal line resilience enhancement strategy to reinforce the target lines;

[0012] Configure energy storage devices for the distribution network, and after comprehensively considering the cost of energy storage device configuration and the energy storage configuration constraints, obtain the optimal energy storage device configuration plan to enhance the redundancy configuration of the distribution network.

[0013] Further, the line resilience enhancement strategies include:

[0014] Strategy 1: Do not take measures;

[0015] Strategy 2: Environmental optimization and reinforcement measures, including trimming the vegetation growing along the line, raising the pole towers and stabilizing the bases;

[0016] Strategy 3: Redundancy strategy for setting operation standby;

[0017] Strategy 4: Environmental optimization and reinforcement measures and redundancy strategy for setting operation standby.

[0018] Further, the calculation expression of the line operation failure probability is:

[0019]

[0020] In the formula, ρ i ′ j is the line operation failure probability of line ij after line resilience enhancement, ρ ij is the line operation failure probability of line ij before line resilience enhancement, h1 is the disaster resistance factor, h2 is the environmental optimization efficiency, and k is the strategy number.

[0021] Further, the expression of the cost constraint of line resilience enhancement is:

[0022]

[0023] F ≤ C u

[0024] In the formula, K is the total number of line resilience enhancement strategies, is the cost generated by line ij adopting the k-th reinforcement strategy, is the strategy selection variable, indicates that the k-th reinforcement strategy is selected, F is the total cost of line reinforcement, and C u is the cost upper limit.

[0025] Further, the calculation expression of the value of load loss caused by line faults is:

[0026]

[0027] Wherein, when i≠j, is the loss value of line ij; when i = j, is the load loss value of node i, w i is the load weight of node i, is the node weight of the power outage due to the failure of line ij, and the weight is selected according to the load level of the power system, P loss,ij is the load of each corresponding power outage node, is the transpose of ω loss,ij ω loss,ij and P loss,ij are both column vectors.

[0028] Furthermore, the calculation expression of the configuration cost of the energy storage device is:

[0029]

[0030] Wherein, is the configuration cost of the energy storage device, β es represents the coefficient for converting the total investment cost of the energy storage system to a one-year period according to the planned years; Ω B represents the set of AC and DC distribution network nodes; c e , c p respectively represent the capacity cost coefficient of the energy storage system and the power cost coefficient of the energy storage system; and P i R respectively represent the capacity and rated power of the energy storage system configured at node i.

[0031] Furthermore, the energy storage configuration constraints include the energy storage system configuration quantity constraint and the energy storage rated power and capacity configuration constraint.

[0032] Furthermore, the expression of the energy storage system configuration quantity constraint is:

[0033]

[0034] Wherein, σ i being 1 indicates that an energy storage system is configured at node i, and σ i being 0 indicates that no energy storage system is configured at node i; represents the maximum allowable configuration quantity of the energy storage system;

[0035] The expression of the energy storage rated power and capacity configuration constraint is:

[0036]

[0037] Wherein, P i R,max and respectively represent the configurable rated power and the upper limit of the capacity of the energy storage system.

[0038] The present invention also provides a power distribution network resilience improvement system for implementing a power distribution network resilience improvement method based on reinforcement and enhanced redundancy as described above, including:

[0039] A line reinforcement module, which is used to calculate the line operation failure probabilities obtained by adopting different line resilience enhancement strategies for the target lines in the power distribution network, and comprehensively consider the cost constraint of line resilience enhancement and the value of load loss caused by line faults, and select the optimal line resilience enhancement strategy to reinforce the target lines;

[0040] An enhanced redundancy configuration module, which is used to configure energy storage devices for the power distribution network, and after comprehensively considering the cost of energy storage device configuration and the energy storage configuration constraints, obtain the optimal energy storage device configuration plan to perform enhanced redundancy configuration on the power distribution network.

[0041] The present invention also provides a computer-readable storage medium, on which a computer program is stored, and the computer program is executed by a processor to perform the method as described above.

[0042] Compared with the prior art, the present invention has the following advantages:

[0043] (1) Before an extreme disaster comes, the system takes preventive measures against possible damages to resist fault disturbances. The reinforcement measures for vulnerable network units are effective means to improve resilience in the prevention stage. The present invention proposes four resilience enhancement strategies for line operation reinforcement, namely taking no measures, environment optimization, redundancy, environment optimization and redundancy. By calculating the line operation failure probability, and comprehensively considering the cost constraint of line resilience enhancement and the value of load loss caused by line faults, the optimal line resilience enhancement strategy is selected to reinforce the target lines, realizing effective and reliable resilience improvement and cost optimization.

[0044] (2) Energy storage devices have the advantages of flexible capacity configuration, fast response speed, stable output power, etc. Under normal conditions, they are mainly applied to peak shaving, frequency modulation, congestion mitigation, voltage support and reactive power control, etc. When an extreme natural disaster occurs, the energy storage device can also be used as an emergency power source to provide power supply guarantee for important load nodes. After comprehensively considering the cost of energy storage device configuration and the energy storage configuration constraints, the present invention obtains the optimal energy storage device configuration plan to perform enhanced redundancy configuration on the power distribution network, which can realize effective and reliable power distribution network resilience improvement and cost optimization. Description of the Drawings

[0045] Figure 1Schematic flow chart of a method for improving the resilience of a distribution network based on reinforcement and enhanced redundancy provided in an embodiment of the present invention;

[0046] Figure 2 Schematic diagram of the topological structure of a three-phase asymmetric IEEE-33 node system provided in an embodiment of the present invention. Detailed implementation manners

[0047] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations.

[0048] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0049] It should be noted that: similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0050] Embodiment 1

[0051] As Figure 1 shown, this embodiment provides a method for improving the resilience of a distribution network based on reinforcement and enhanced redundancy, including the following steps:

[0052] S1: Calculate the line operation failure probabilities obtained by using different line resilience enhancement strategies for the target lines in the distribution network, and comprehensively consider the cost constraints of line resilience enhancement and the value of load loss caused by line faults, and select the optimal line resilience enhancement strategy to reinforce the target lines;

[0053] S2: Configure energy storage devices for the distribution network, and after comprehensively considering the cost of energy storage device configuration and energy storage configuration constraints, obtain the optimal energy storage device configuration plan to perform enhanced redundancy configuration on the distribution network.

[0054] The following is a specific description of each part:

[0055] 1. Line reinforcement measure S1

[0056] Before extreme disasters strike, the system takes preventive measures against possible damages to resist fault disturbances. Strengthening measures for vulnerable network units are effective means to enhance resilience during the prevention stage.

[0057] The line strengthening measures also need to consider the value of load loss caused by line faults, and its matrix L value is:

[0058]

[0059] where, when i≠j is the loss value of line ij, when i = j, is the load loss value of node i, w i is the load weight of node i, is the weight of the nodes that lose power due to the fault of line ij, and the weight is selected according to the load level of the power system, P loss,ij is the load of each corresponding power - off node is the transpose of ω loss,ij ω loss,ij and P loss,ij are both column vectors.

[0060] To cope with extreme disaster disturbances, for lines, environmental optimization and strengthening technologies such as trimming the vegetation growing along the line, raising the pole towers, and stabilizing the base can be adopted. In addition, the system resilience can be improved by setting redundant strategies for operation reserve. Based on this, four resilience - enhancing strategies for line operation reinforcement are proposed: no measure, environmental optimization, redundancy, and environmental optimization and redundancy. The failure probability ρ of the reinforced line operation ′ is:

[0061]

[0062] where, h1 is the disaster resistance factor, h2 is the environmental optimization efficiency, and k is the strategy number.

[0063] Due to the cost generated by the optimization strategy, line strengthening must be optimally selected within a certain cost range, and the constraints are as follows:

[0064]

[0065] F≤C u

[0066] where, k is the optimization strategy set, is the cost generated by adopting the k - th strengthening strategy for line ij, is the strategy selection variable, indicates that the k - th strengthening strategy is selected, F is the total cost of line strengthening, and C u is the cost ceiling.

[0067] 2. Enhanced Redundancy Measure S2

[0068] In recent years, with the continuous maturity of energy storage device technologies, the cost of energy storage batteries has been continuously decreasing, and the proportion of energy storage devices in the distribution network has been increasing. Energy storage devices have the advantages of flexible capacity configuration, fast response speed, and stable output power. Under normal conditions, they are mainly applied to peak shaving, frequency modulation, congestion mitigation, voltage support, and reactive power control, etc.; when extreme natural disasters occur, energy storage devices can also be used as emergency power supplies to provide power supply guarantees for important load nodes.

[0069] The energy storage configuration cost is linearly related to the total capacity and rated power of the energy storage system:

[0070]

[0071] In the formula: β es represents the coefficient for converting the total investment cost of the energy storage system to a one-year period according to the planned years; Ω B represents the set of AC and DC distribution network nodes; c e , c p respectively represent the capacity cost coefficient and power cost coefficient of the energy storage system; and P i R respectively represent the capacity and rated power of the energy storage system configured at node i.

[0072] The energy storage configuration needs to meet the following constraints. The constraints for the operation of the energy storage system are not elaborated here:

[0073] 2.1 Energy Storage System Configuration Quantity Constraint

[0074]

[0075] In the formula: σ i When it is 1, it means that an energy storage system is configured at node i, otherwise it is not configured; represents the maximum allowable configuration quantity of the energy storage system.

[0076] 2.2 Energy Storage Rated Power and Capacity Configuration Constraint

[0077]

[0078] In the formula: P i R,max and respectively represent the upper limits of the rated power and capacity that can be configured for the energy storage system.

[0079] 3. Case Study

[0080] To verify the effectiveness of the above method, the proposed method is verified on the three-phase unbalanced IEEE-33 node system, and the case topology is asFigure 2 As shown in the figure, the example includes 33 nodes and 32 lines. DG in the figure represents distributed power sources. Among them, the AC distribution network voltage level is 12.66 kV. On the basis of the radial distribution network, 4 new lines are added to increase its loop redundancy. The distributed power sources connected to the AC distribution network are all dispatchable gas turbines, and the new energy units are only connected to the DC distribution network. The upper limit of the line load capacity and the allowable passing upper limit of the apparent power of the VSC tie line are both set to 2 MVA. The resistance and reactance of the VSC are taken as 0.2 Ω and 0.6 Ω respectively. The maximum number of lines for reinforcement is set to 3, and the cost of single-line reinforcement is 1000 yuan / m. The length of all lines is 1 km. The technical parameters of the energy storage system are shown in Table 1, and the costs have been converted to an annual basis. Assuming that before the extreme event occurs, the distribution network operator has received a fault warning message and taken preventive measures in advance, the initial SOC of the energy storage is set to 0.85. Considering that the extreme event occurs 5 times within one year, the failure rate before line reinforcement is 0.9, and the failure rate after reinforcement is 0.1.

[0081] The example will design 2 different scenarios to analyze the strategies for improving the resilience of the urban distribution network.

[0082] Scenario 1: Do not adopt the pre-disaster resilience improvement strategy.

[0083] Scenario 2: Only adopt the line reinforcement strategy.

[0084] The test results are shown in Tables 2 and 3.

[0085] Table 2 Comparison of the effects of resilience improvement strategies under different scenarios

[0086]

[0087] Table 3 Load shedding conditions under different scenarios

[0088] Scenario First-level load shedding amount / (kWh) Other load shedding amount / (kWh) 1 1137.6 10791.6 2 858.2 7323.3

[0089] If no pre-disaster defense strategy is adopted, the extreme event directly causes about 57% of the first-level load shedding in the AC-DC hybrid distribution network, resulting in huge economic losses. Although this measures the worst-case scenario, it has very important practical significance. The types of extreme events include not only natural disasters but also a high proportion of human attacks. Natural disasters are accidental, while malicious attacks often have strong directivity. Therefore, analyzing the pre-disaster defense strategy in the most severe fault situation is also the result of seeking certainty in contingency. In Scenario 2, the line reinforcement strategy is adopted, and the objective function is reduced by 10.7% compared with Scenario 1. Compared with the scenario without line reinforcement, the resilience improvement effect is obvious.

[0090] Therefore, the method for improving resilience by considering line reinforcement strategies can serve as a reference for power grid dispatchers' decision-making in power outage accidents. While reinforcing lines, it can supply power to critical loads through the coordinated cooperation of local resources and mobile power generation resources, reducing various losses caused by power interruption.

[0091] Embodiment 2

[0092] This embodiment provides a power grid resilience improvement system for implementing a power grid resilience improvement method based on reinforcement and enhanced redundancy as described in Embodiment 1, including:

[0093] A line reinforcement module, which is used to calculate the line operation failure probabilities obtained by adopting different line resilience enhancement strategies for the target lines in the power grid, and comprehensively consider the cost constraints of line resilience enhancement and the value of load losses caused by line faults, and select the optimal line resilience enhancement strategy to reinforce the target lines;

[0094] An enhanced redundancy configuration module, which is used to configure energy storage devices for the power grid, and after comprehensively considering the energy storage device configuration cost and energy storage configuration constraints, obtain the optimal energy storage device configuration plan to perform enhanced redundancy configuration on the power grid.

[0095] It should be noted that the specific content and beneficial effects of the system of this application can be referred to the above method embodiments and will not be elaborated here.

[0096] Embodiment 3

[0097] This embodiment provides a computer-readable storage medium, on which a computer program is stored, and the computer program is executed by a processor to perform the steps of the power grid resilience improvement method based on reinforcement and enhanced redundancy as described in Embodiment 1.

[0098] The computer-readable storage medium can be a tangible medium, which can contain or store a program for use by or in connection with an instruction execution system, apparatus, or device. The computer-readable storage medium can be a machine-readable signal medium or a machine-readable storage medium. The computer-readable storage medium can include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatuses, or devices, or any suitable combination of the above. More specific examples of the machine-readable storage medium would include electrical connections based on one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the above.

[0099] The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those of ordinary skill in the art can make many modifications and variations based on the concept of the present invention without creative efforts. Therefore, all technical solutions that can be obtained by those skilled in the art in the technical field based on the concept of the present invention through logical analysis, reasoning, or limited experiments on the basis of the prior art shall fall within the protection scope determined by the claims.

Claims

1. A method for improving the resilience of a distribution network based on reinforcement and enhanced redundancy, characterized in that, It includes the following steps: Calculate the line operation failure probabilities obtained by adopting different line resilience enhancement strategies for the target lines in the distribution network respectively, and comprehensively consider the cost constraint of line resilience enhancement and the value of load loss caused by line faults, and select the optimal line resilience enhancement strategy to reinforce the target lines; Configure energy storage devices for the distribution network, and after comprehensively considering the energy storage device configuration cost and energy storage configuration constraints, obtain the optimal energy storage device configuration plan to perform enhanced redundancy configuration on the distribution network.

2. A method for improving the resilience of a distribution network based on reinforcement and enhanced redundancy according to claim 1, characterized in that, The line resilience enhancement strategies include: Strategy 1: Do not take measures; Strategy 2: Environmental optimization and reinforcement measures, including trimming the vegetation growing along the line, raising the poles and stabilizing the bases; Strategy 3: Redundancy strategy for setting up operating reserves; Strategy 4: Environmental optimization and reinforcement measures and redundancy strategy for setting up operating reserves.

3. A method for improving the resilience of a distribution network based on reinforcement and enhanced redundancy according to claim 2, characterized in that, The calculation expression of the line operation failure probability is: where ρ i ′ j is the line operation failure probability of line ij after the line toughness is enhanced, and ρ ij is the line operation failure probability of line ij before the line toughness is enhanced, h1 is the disaster resistance factor, h2 is the environmental optimization efficiency, and k is the strategy number.

4. A method for improving the resilience of a distribution network based on reinforcement and enhanced redundancy according to claim 3, characterized in that, The expression of the cost constraint of line resilience enhancement is: F ≤ C u Where K is the total number of line toughness enhancement strategies, is the cost generated by the k-th reinforcement strategy adopted by line ij, is the strategy selection variable, indicates that the k-th reinforcement strategy is selected, F is the total cost of line reinforcement, and C u is the cost ceiling.

5. A method for improving the resilience of a distribution network based on reinforcement and enhanced redundancy according to claim 1, characterized in that, The calculation expression of the value of load loss caused by line faults is: Wherein, when i≠j, is the loss value of line ij; When i = j, is the value of load loss of node i, w i is the load weight of node i, is the weight of the node that loses power due to the failure of line ij. The weight is selected according to the load level of the power system, P loss,ij is the load of each corresponding power - loss node, is the transpose of ω loss,ij , ω loss,ij and P loss,ij are both column vectors.

6. A method for improving the resilience of a distribution network based on reinforcement and enhanced redundancy according to claim 1, characterized in that The calculation expression of the energy storage device configuration cost is: In the formula, is the configuration cost of the energy storage device, and β es represents the coefficient for converting the total investment cost of the energy storage system to a one-year period according to the planned years; Ω B represents the set of AC and DC distribution network nodes; c e and c p represent the capacity cost coefficient and the power cost coefficient of the energy storage system respectively; and represent the capacity and rated power of the energy storage system configured at node i respectively.

7. A method for improving the resilience of a distribution network based on reinforcement and enhanced redundancy according to claim 6, characterized in that, The energy storage configuration constraints include the energy storage system configuration quantity constraint and the energy storage rated power and capacity configuration constraint.

8. A method for improving the resilience of a distribution network based on reinforcement and enhanced redundancy according to claim 7, characterized in that, The expression of the energy storage system configuration quantity constraint is: where, σ i being 1 indicates that the node i is configured with an energy storage system, and σ i being 0 indicates that the node i is not configured with an energy storage system; represents the maximum allowable number of configured energy storage systems; The expression of the energy storage rated power and capacity configuration constraint is: In the formula, and respectively represent the configurable rated power and the upper limit of the capacity of the energy storage system.

9. A distribution network resilience improvement system for implementing a distribution network resilience improvement method based on reinforcement and enhanced redundancy as described in any one of claims 1-8, characterized in that, It includes: A line reinforcement module, which is used to calculate the line operation failure probabilities obtained by adopting different line resilience enhancement strategies for the target lines in the distribution network respectively, and comprehensively consider the cost constraint of line resilience enhancement and the value of load loss caused by line faults, and select the optimal line resilience enhancement strategy to reinforce the target lines; An enhanced redundancy configuration module, which is used to configure energy storage devices for the distribution network, and after comprehensively considering the energy storage device configuration cost and energy storage configuration constraints, obtain the optimal energy storage device configuration plan to perform enhanced redundancy configuration on the distribution network.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, and the computer program is executed by a processor to perform the method according to any one of claims 1 to 8.

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