A reliability evaluation method and system for a flexible power distribution network structure

Abstract

A reliability evaluation method of a flexible power distribution network structure comprises the following steps: constructing a reliability evaluation model of the flexible power distribution network structure, wherein the reliability evaluation model comprises a reliability index calculation model in a normal operation state of the power distribution network and a reliability index calculation model in a fault state of the power distribution network; constructing a simulation model of the flexible power distribution network structure; obtaining operation data in the normal operation state of the flexible power distribution network and operation data in the fault state of the flexible power distribution network through the simulation model; calculating the reliability index in the normal operation state of the power distribution network according to the operation data in the normal operation state of the power distribution network and the reliability evaluation model; and calculating the reliability index in the fault state of the power distribution network according to the operation data in the fault state of the power distribution network and the reliability evaluation model. The design can comprehensively and accurately evaluate the reliability of the flexible power distribution network structure.

Description

Technical Field

[0001] This invention relates to the field of power transmission and distribution technology, and in particular to a reliability assessment method and system for flexible power distribution network structures. Background Technology

[0002] With the rapid development of the power industry and continuous technological advancements, power distribution systems are gradually becoming more complex and flexible. On the one hand, the integration of new power elements such as distributed power sources, energy storage devices, and standard operating procedures (SOPs) makes the structure of power distribution systems more complex and variable. On the other hand, users have increasingly higher requirements for the reliability and stability of power supply, necessitating that the power distribution network possess stronger adaptive and fault recovery capabilities.

[0003] With the continuous growth of electricity demand and the increasing complexity of power grid structures, traditional distribution network structures can no longer meet the demands of modern power systems for high reliability, high flexibility, and efficient operation. Modern distribution network structures introduce flexible structures to enhance adaptability and flexibility, thereby better meeting the future development requirements of the power industry. However, existing methods for analyzing the reliability of distribution networks often fail to comprehensively and accurately reflect the performance of highly reliable and flexible distribution systems under complex operating conditions. Furthermore, existing technologies have limitations when handling large-scale data and scenarios with high real-time requirements. Based on these issues, this invention proposes a reliability analysis method based on a flexible distribution network structure. This method, based on a flexible distribution network structure, comprehensively considers various factors to achieve a quantitative assessment of the power supply reliability of the distribution network under different operating conditions. It optimizes the power supply reliability assessment methods of the distribution network, enhances its flexible response capability under complex and variable operating conditions, and provides strong technical support and decision-making basis for the design, operation, and management of distribution networks. Summary of the Invention

[0004] The purpose of this invention is to overcome the problem that existing power distribution network reliability analysis methods are unable to fully and accurately reflect the reliability of flexible power distribution systems under complex operating conditions, and to provide a reliability assessment method and system for flexible power distribution network structures.

[0005] To achieve the above objectives, the technical solution of the present invention is:

[0006] In a first aspect, the present invention provides a reliability assessment method for flexible power distribution network structures, comprising:

[0007] S1. Construct a reliability assessment model for a flexible distribution network structure. The reliability assessment model includes a reliability index calculation model under normal operating conditions and a reliability index calculation model under fault conditions.

[0008] S2. Construct a simulation model of a flexible power distribution network structure;

[0009] S3. Obtain the operating data of the flexible distribution network under normal operating conditions and the operating data of the flexible distribution network under fault conditions through the simulation model;

[0010] S4. Calculate the reliability index of the distribution network under normal operating conditions based on the operating data and reliability assessment model.

[0011] The reliability index of the distribution network under fault conditions is calculated based on the operating data and reliability assessment model.

[0012] The operating data of the distribution network under normal operating conditions include: the power transmitted by each line in the distribution network, the voltage amplitude of each node in the distribution network, and the frequency of each node in the distribution network;

[0013] The operational data under the fault operation status of the distribution network includes: the protection action time after the distribution network fault occurs, the total load capacity of the power outage area after the protection action takes effect, the time required to complete the load transfer after the distribution network fault occurs, and the total load capacity transferred.

[0014] The reliability index calculation model for the power distribution network under normal operating conditions includes:

[0015]

[0016] In the formula, R Operation The reliability of the distribution network under normal operating conditions; N is the total number of lines in the distribution network; M is the total number of nodes in the distribution network; S Line i S represents the amount of electricity transmitted by line i in the distribution network per unit time; Line-N i U represents the rated capacity of line i in the distribution network; j U is the phase voltage amplitude at node j; N j f is the rated phase voltage of node j; j f is the frequency of node j; N j Let be the rated frequency of node j.

[0017] The reliability index calculation model for distribution network under fault conditions includes:

[0018] R Supply =α·R Relay +(1-α)·R Recover ;

[0019] In the formula, R Supply R is a reliability indicator for distribution network under fault conditions. Relay To protect reliability; RRecover α represents the reliability of fault recovery; α is the weighting coefficient.

[0020] The protection reliability R Relay Calculate using the following formula:

[0021]

[0022] In the formula, t Trip The protection operation time after a distribution network fault occurs; t max Maximum protection duration; S Transformer The total load capacity of the area affected by the power outage after the protection action takes effect; S max This represents the total load of the distribution network.

[0023] The fault recovery reliability R Recover Calculate using the following formula:

[0024]

[0025] In the formula, t Recover The time required to complete load transfer after a distribution network fault occurs; Maximum load transfer time; S Recover For transferring load capacity; S out The total capacity of the 10kV and 0.4kV transformers in the power outage area; S represents the amount of electricity transmitted by line i in the distribution network per unit time after load transfer; Line-N i This represents the rated capacity of line i in the distribution network.

[0026] The following steps are taken to obtain operational data of the flexible distribution network under fault conditions using the simulation model:

[0027] S301. Set fault points at different locations in the simulation model of the AC power grid;

[0028] S302. Simulate different types of faults at each fault point and obtain the operation data of the distribution network under the condition that different types of line faults occur at each fault point.

[0029] Secondly, the present invention provides a reliability assessment system for flexible power distribution network structures, comprising:

[0030] The evaluation model construction module is used to construct a reliability evaluation model for a flexible distribution network structure. The reliability evaluation model includes a reliability index calculation model under normal operation of the distribution network and a reliability index calculation model under fault conditions.

[0031] The simulation model building module is used to build simulation models of flexible power distribution network structures.

[0032] The data acquisition module is used to acquire operating data of the distribution network under normal operating conditions and operating data of the distribution network under fault conditions through the simulation model.

[0033] The indicator calculation module is used to calculate the reliability indicators of the distribution network under normal operating conditions based on the operating data of the distribution network under normal operating conditions.

[0034] Thirdly, the present invention provides an evaluation device, including a memory and a processor, wherein the memory is used to store computer program code and to transmit the computer program code to the processor;

[0035] The processor is used to execute the aforementioned reliability assessment method for flexible power distribution network structures according to instructions in the computer program code.

[0036] Fourthly, the present invention provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps in the above-described reliability assessment method for flexible power distribution network structures.

[0037] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0038] 1. This invention provides a reliability assessment method for flexible distribution network structures, establishing an evaluation index system for the flexible distribution network structure. This system includes reliability indices under normal operating conditions and reliability indices under fault conditions. The reliability index under normal operating conditions is calculated by integrating parameters such as flexible line load factor, flexible voltage stability, and flexible frequency control accuracy. The reliability index under fault conditions is calculated by integrating parameters such as protection reliability and fault recovery reliability, accurately reflecting the performance of the distribution network under different operating conditions and providing more accurate data support for subsequent quantitative analysis and optimization. Therefore, this design establishes an evaluation index system for flexible distribution network structures, accurately reflecting the performance of the distribution network under different operating conditions and providing more accurate data support for subsequent quantitative analysis and optimization.

[0039] 2. In the reliability assessment method for flexible distribution network structures proposed in this invention, the reliability index under distribution network fault conditions integrates the evaluation of protection reliability and power restoration reliability, and comprehensively considers the network topology and load demand. Specifically, protection reliability comprehensively considers distributed power source control strategies, protection action time, and fault identification, and quantifies the protection action of the distribution network structure using the flexible protection action speed and the capacity of flexible transformers within the outage area, accurately reflecting the response speed and impact range of the power grid in the initial stage of a fault. Power restoration reliability is reflected by the flexible load transfer speed and transfer load capacity, which directly determines the recovery speed and efficiency of the power grid after a fault. Furthermore, this method allocates the weights of protection reliability and power restoration reliability according to actual needs, enabling a more accurate assessment of the performance of the flexible distribution network structure, thus providing strong data support for the design, operation, and management of the distribution network. Therefore, this design comprehensively considers the network topology and load demand to design reliability indices under distribution network fault conditions, allocates the weights of protection reliability and power restoration reliability according to actual needs, and the evaluation results can comprehensively and accurately reflect the true situation of the flexible distribution network structure.

[0040] 3. In the reliability assessment method for flexible distribution network structures proposed in this invention, a simulation model of the flexible distribution network structure is used to accurately simulate the reliability performance of the flexible distribution network under complex and changing operating environments. Furthermore, when building the simulation model, not only are basic fault state simulations considered, but also factors such as different fault locations, fault types, and the impact time caused by different faults are refined, making the simulation results closer to the actual operating conditions of the distribution network. Therefore, the simulation results of this design are closer to the actual operating conditions of the distribution network. Attached Figure Description

[0041] Figure 1 This is a schematic flowchart of a reliability assessment method for flexible power distribution network structures provided in an embodiment of the present invention.

[0042] Figure 2 This is a topology diagram of three flexible connection structures for power distribution networks provided in the embodiments of the present invention.

[0043] Figure 3 This is a topology diagram of a power distribution network simulation model based on three different flexible connection structures.

[0044] Figure 4 This is a schematic diagram of a simulation model of a flexible distribution network containing distributed power sources.

[0045] Figure 5 This is a schematic diagram of a reliability assessment system for flexible power distribution networks.

[0046] Figure 6 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention. Detailed Implementation

[0047] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0048] With advancements in power technology, modern distribution networks have incorporated flexible structures to enhance their adaptability and flexibility. Flexible distribution networks, with their superior flexibility, adjustable network structure, and advanced intelligent control technology, achieve efficient power flow scheduling and immediate response to grid changes. Simultaneously, with the intelligent development of power grid technology, grid "self-healing" technology enables modern power grids to achieve self-monitoring, self-diagnosis, and self-repair, thereby ensuring the stable, reliable, and safe operation of the grid. However, for modern power grids that incorporate flexible structures and intelligent control technologies, traditional reliability indicators are no longer sufficient to comprehensively assess their performance.

[0049] To address the aforementioned technical problems, this invention provides a more accurate, comprehensive, and efficient method for assessing the reliability of flexible power distribution networks, in order to meet the increasing complexity and flexibility requirements of modern power distribution systems. Figure 1 As shown, Figure 1 This is a flowchart illustrating a reliability assessment method for a flexible power distribution network structure provided in an embodiment of the present invention, which includes steps S1 to S4.

[0050] S1. Construct a reliability assessment model for flexible power distribution network structures;

[0051] The reliability assessment model includes a reliability index calculation model under normal operating conditions of the distribution network and a reliability index calculation model under fault conditions of the distribution network.

[0052] In this embodiment, the reliability assessment model includes a reliability index calculation model under normal operating conditions of the distribution network and a reliability index calculation model under fault conditions of the distribution network.

[0053] The power supply reliability of a flexible distribution network under normal operating conditions is mainly measured by the flexible line load factor, flexible voltage stability, and flexible frequency control accuracy. Specifically, the calculation model for the reliability indicators of the distribution network under normal operating conditions includes:

[0054]

[0055] In the formula, R Operation The reliability of the distribution network under normal operating conditions; N is the total number of lines in the distribution network; M is the total number of nodes in the distribution network; S Line i The amount of electricity transmitted by line i in the distribution network per unit time;

[0056] S Line-Ni U represents the rated capacity of line i in the distribution network. The rated capacity of a line refers to its capacity to operate continuously under rated operating conditions (such as rated voltage and rated current) without exceeding its design limits. It is an important parameter determined during line design and manufacturing, and the rated capacity of a line is a fixed value. j U is the phase voltage amplitude at node j; N j f is the rated phase voltage of node j; j f is the frequency of node j; N j Let be the rated frequency of node j.

[0057] To comprehensively assess the reliability of a distribution network under normal operating conditions, we primarily focus on three core indicators: flexible line load factor, flexible voltage stability, and flexible frequency control accuracy. Among these, the flexible line load factor reflects the utilization rate of the load, which we use as... The term "flexible voltage stability" reflects the ability to maintain voltage stability. This is expressed as [the standard term]; while the precision of flexible frequency control reveals the accuracy of frequency control, which we represent using [the standard term]. The three indicators—flexible line load factor, flexible voltage stability, and flexible frequency control accuracy—together constitute the reliability assessment system for the distribution network under normal operating conditions. This helps us monitor the network's operating status in real time and ensure that the distribution network can supply power stably and reliably.

[0058] The reliability index calculation model for distribution network under fault conditions includes:

[0059] R Supply =α·R Relay +(1-α)·R Recover ;

[0060] In the formula, R Supply R is a reliability indicator for distribution network under fault conditions. Relay To protect reliability; R Recover The weight α represents the reliability of fault recovery; α is the weighting coefficient. The larger α is, the more important the protection reliability is. The smaller α is, the more important the fault recovery reliability is. In practical applications, the weight α can be adjusted according to the actual situation. In this embodiment, the weight α is 0.6.

[0061] When a distribution network experiences a fault, the reliability of its protection actions and fault recovery capabilities become crucial in measuring its power supply reliability. Therefore, the reliability indicators of a distribution network under fault conditions are quantified into two parts: protection reliability and fault recovery reliability. Especially for distribution networks containing distributed generation (DG), it is necessary to consider DG control strategies, fault characteristics, protection action time, and the accuracy of fault identification to quantitatively analyze the protection reliability of distribution networks with DG. Furthermore, by analyzing all possible fault events and their consequences on the distribution network system, the consequences of fault modes are analyzed, thereby quantifying the fault recovery reliability of distribution networks with DG.

[0062] In the event of a line fault, ensuring that the protection device can accurately and quickly disconnect the faulty line and effectively isolate the power outage area is a prerequisite for implementing fault recovery work. Regarding protection reliability, we use R... Relay To represent the protection reliability of the distribution network, we consider the operating speed of flexible protection and the capacity of flexible transformers in the outage area. To quantify the speed of the protective action, in order to These two parameters, used to quantify the capacity of flexible transformers within the power outage area, can quickly reflect the power grid's response speed and impact range in the early stages of a fault.

[0063] The protection reliability R Relay Calculate using the following formula:

[0064]

[0065] Specifically, in protecting reliability R Relay In the calculation formula, taking a distribution network equipped with three-stage current protection as an example, the protection action speed is divided into 0s action (representing current stage I action), 0.3s action (representing current stage II action), and 0.6s action (representing current stage III action; in practice, any action ≥ 0.6s is replaced with 0.6s); t Trip t represents the protection operation time after a distribution network fault occurs. max To protect the maximum duration of the action, t max We will use 0.6 seconds for the calculation. That is, t Trip Normalization, S Transformer To determine the total load capacity of the power outage area after the protection action takes effect, S max For the total load of the distribution network, That is to put S Transformer Normalization process.

[0066] After the fault is automatically cleared by protection actions, some areas will experience power outages. The fault recovery strategy provided by the distribution network will restore power to some or all of the out-of-power loads through load transfer. To quantify fault recovery reliability, we use the flexible load transfer speed, the transferred load capacity, and the overload warning capability of flexible lines as indicators. We use R... Recover To represent the fault recovery reliability of the distribution network, we use To quantify the speed of flexible load transfer, in order to To quantify the load transfer capacity, in order to To quantify the overload situation of flexible lines, these three parameters directly reflect the recovery speed and efficiency of the power grid after a fault. In addition, we need to consider extra factors such as the overload early warning capability of flexible lines to more comprehensively assess the impact of faults on the overall power supply reliability of the power grid. Reliability indicators under distribution network fault conditions provide us with a basis for decision-making, enabling us to more effectively respond to power grid faults and ensure the continuity and stability of power supply.

[0067] The fault recovery reliability R Recover Calculate using the following formula:

[0068]

[0069] In the formula, t Recover The time required to complete load transfer after a distribution network fault occurs is quantified as the time for load transfer after protection action for modern distribution networks equipped with self-healing. Specifically, if there are no distributed power sources in the area to be restored, the time required to complete load transfer is 0.3 seconds. If there are distributed power sources in the area to be restored, the time required to complete load transfer also needs to be increased by 2 seconds for the anti-islanding protection action time. The maximum load transfer time is set to 3.2 seconds. That is, t Recover Normalization; S Recover The load transfer capacity is the sum of the transformer capacities that are restored to power after a power outage; S out The total capacity of transformers in the area experiencing a power outage due to a fault. That is to put S Recover Normalization processing; S represents the amount of electricity transmitted by line i in the distribution network per unit time after load transfer; Line-N i This represents the rated capacity of line i in the distribution network.

[0070] In this embodiment, the protection action time and load transfer time will differ depending on the location of the fault in the flexible distribution network. Therefore, the protection reliability and fault recovery reliability will also differ; that is, the reliability indicators of the distribution network under different fault scenarios are not the same. This method can be used to calculate and obtain the power supply reliability of the flexible distribution network under different fault scenarios.

[0071] In summary, in the field of modern smart grid technology, flexible distribution networks, with their superior flexibility, adjustable network structure, and advanced intelligent control technology, achieve efficient power flow scheduling and real-time response to grid changes. Based on the flexible distribution network structure, we propose a more accurate reliability assessment model and evaluation indicators. Specifically, the reliability assessment indicator system is shown in Table 1:

[0072]

[0073]

[0074] Table 1 Reliability index system of distribution network under different operating conditions

[0075] The evaluation indicators in Table 1 cover parameters under normal operating conditions and emphasize key elements under fault conditions. The aim is to more accurately reflect the reliability level of flexible distribution networks under different operating conditions, provide a scientific basis for the optimized design, operation management and fault response of the power grid, and promote the development of the power grid towards a more intelligent, green and sustainable direction.

[0076] S2. Construct a simulation model of a flexible power distribution network structure.

[0077] S3. Obtain operating data under normal operating conditions and operating data under fault conditions of the distribution network through the simulation model.

[0078] In this embodiment, the steps for obtaining operational data of a flexible distribution network under fault conditions through the simulation model are as follows:

[0079] S201. Set fault points at different locations in the simulation model of the AC power grid;

[0080] S202. Simulate different types of faults at each fault point and obtain simulation data of power distribution network operation under different types of line faults at each fault point.

[0081] S4. Calculate the reliability index of the distribution network under normal operating conditions based on the operating data and reliability assessment model.

[0082] The reliability index of the distribution network under fault conditions is calculated based on the operating data and reliability assessment model under power grid fault conditions.

[0083] After calculating the reliability indicators of the distribution network under normal operating conditions and under different fault conditions, corresponding fault response measures can be proposed based on the reliability indicators of the distribution network under different fault conditions. At the same time, the reliability indicators of multiple distribution networks with different structures under normal operating conditions and under different fault conditions can also be calculated, and the distribution networks with different structures can be compared and selected based on the calculation results, providing a scientific basis for the optimal design, operation management and fault response of the power grid.

[0084] This invention provides a reliability assessment method for flexible distribution network structures. The method includes building a quantitative calculation model of reliability indicators under normal operation and fault conditions of the distribution network based on a flexible interconnection structure. It also comprehensively considers various factors such as structure, equipment performance, and load demand to achieve dynamic and accurate assessment and optimization of the distribution network under various operating conditions. The aim is to overcome the limitations of existing technologies, improve the power supply reliability and flexibility of the distribution network, and better adapt to the future development needs of the power industry.

[0085] New flexible power grid structures can address the shortcomings of traditional distribution network structures in terms of adaptability and flexibility. However, current reliability analysis methods for flexible distribution network structures still face many challenges. Traditional reliability analysis methods are mainly based on fixed network topologies and defined failure modes, making it difficult to accurately capture the dynamic changes and uncertainties introduced by flexible interconnection structures in flexible distribution networks. Therefore, developing reliability analysis methods suitable for flexible distribution network structures is particularly important.

[0086] We selected three different flexible connection structures in the distribution network and used the aforementioned reliability assessment method for flexible distribution network structures to calculate the reliability indicators under normal operation and fault conditions. Based on the calculation results, we evaluated and compared the reliability of the distribution networks with different flexible connection structures. Figure 2 As shown, Figure 2 The paper presents three topologies for flexible connection structures in distribution networks: single-ended flexible closed-loop structure between feeders, multi-ended flexible interconnection structure between ring networks, and mesh-type multi-ended flexible interconnection structure.

[0087] Based on the topologies of the three flexible distribution network structures mentioned above, we built a simulation model, such as... Figure 3 As shown, Figure 3 The diagram shows the topology of a power distribution network simulation model based on three different flexible connection structures. Figure 3 (a) is a topology diagram of a single-end flexible closed-loop structure between feeders in a flexible distribution network. Figure 3 (b) is a topology diagram of the flexible distribution network with multi-terminal flexible interconnection structure between ring networks. Figure 3(c) is a topology diagram of a flexible distribution network in a mesh-type multi-terminal flexible interconnection structure.

[0088] We further configured the fault and penetration rates of the distribution network, such as... Figure 4 As shown, Figure 4 This is a schematic diagram of a simulation model of a flexible distribution network containing distributed generation. We set five line fault injection points (f1-f5) on different lines in the simulation model. Then, we set the distributed generation penetration rate. Distributed generation is connected to various substations and distribution stations in the flexible distribution network. The distributed generation penetration rate is obtained by dividing the capacity of the connected distributed generation by the capacity of the load connected between substation A and substation G. The formula for calculating the distributed generation penetration rate of the distribution network is as follows:

[0089]

[0090] In the formula, Permeability is the distributed generation penetration rate of the distribution network, S PV S represents the capacity of distributed power sources connected to the distribution network. Load The capacity of the load connected to the distribution network.

[0091] We calculated the power supply reliability of the flexible distribution network under normal operating conditions through simulation analysis, as shown in Table 2 below. Table 2 shows the reliability of the flexible distribution network with distributed generation under normal operating conditions under three flexible connection structures, where S... Load Taking 3MW as an example, the penetration rates of distributed power sources are 0%, 20%, 40%, 60%, 80%, and 100%, respectively.

[0092]

[0093] Table 2 Reliability of Distribution Network under Normal Operating Conditions

[0094] As shown in the table above, the power supply reliability of the distribution network is highest when the penetration rate of distributed generation is 0%, followed by the distribution network when the penetration rate of distributed generation is 40%, while the power supply reliability of the distribution network is lowest when the penetration rate of distributed generation is 100%. Comparing the three flexible interconnection structures, the mesh-type multi-terminal flexible interconnection structure has the highest power supply reliability at any penetration rate, followed by the ring network multi-terminal flexible interconnection structure, and the lowest reliability is the feeder single-terminal flexible interconnection structure.

[0095] As the above analysis shows, the single-ended flexible closed-loop structure between feeders can significantly improve the power supply reliability of the distribution network by adjusting the active and reactive power of the converter, thereby regulating the active and reactive power of the two feeders. This is particularly effective in mitigating voltage rise and line overload at the end of the line. The multi-ended flexible interconnection structure between ring networks is similar to the single-ended flexible closed-loop structure between feeders; both can adjust the active and reactive power of the converter, thereby regulating the active and reactive power of the two feeders and mitigating voltage rise and line overload at the end of the line. Therefore, the power supply reliability of the distribution network using the multi-ended flexible interconnection structure between ring networks is similar to that of the single-ended flexible closed-loop structure between feeders. The mesh-type multi-ended flexible interconnection structure, with its more diverse power adjustment paths, offers more flexible means to mitigate voltage rise and line overload at the end of the line, and its power supply reliability is improved compared to the multi-ended flexible interconnection structure between ring networks.

[0096] We then used simulation analysis to calculate the power supply reliability of the constructed flexible distribution network under fault conditions, as shown in Table 3 below. Table 3 shows the reliability of the distribution network under fault conditions when short-circuit faults occur at f1-f5 under three different flexible connection structures, where the penetration rate of distributed power sources is 0%, 20%, 40%, 60%, 80%, and 100%, respectively.

[0097]

[0098] Table 3 Reliability of Distribution Network under Fault Conditions

[0099] As shown in the table above, the power supply reliability of the distribution network is highest when the penetration rate of distributed generation is 0% and the fault location is f3. When the penetration rate of distributed generation is 0%, the reliability is relatively high at all five fault locations. Overall, the power supply reliability is high at fault location f3 regardless of the distributed generation penetration rate. The power supply reliability is lowest when the penetration rate of distributed generation is 20% and the fault location is f5, with relatively low reliability at fault locations f1 and f5. Comparing the three flexible interconnection structures, the mesh-type multi-terminal flexible interconnection structure has the highest power supply reliability at any penetration rate and any fault location, followed by the ring network multi-terminal flexible interconnection structure, while the feeder single-terminal flexible interconnection structure has the lowest reliability.

[0100] As the above analysis shows, for the power supply reliability of the distribution network during a fault, the single-ended flexible closed-loop structure between feeders still simply transfers the out-of-power load to the opposite feeder, without significantly improving power supply reliability. The multi-ended flexible interconnection structure between ring networks provides an additional transfer path compared to the single-ended flexible closed-loop structure between feeders, thus reducing line overload and improving power supply reliability. The mesh-type multi-ended flexible interconnection structure offers more diverse load transfer paths than the multi-ended flexible interconnection structure between ring networks, allowing transfer via ordinary tie switches or SOPs, further reducing line overload and improving power supply reliability.

[0101] This invention, by comprehensively considering various factors such as load demand, network topology, equipment status, and fault simulation, aims to quantitatively assess the power supply reliability of distribution networks under both normal and fault conditions. Based on the assessment results, it proposes optimization suggestions and fault response measures. This not only helps improve the fault response capability and overall operational efficiency of distribution networks but also significantly reduces the failure rate and outage time, providing users with a more stable and reliable power supply, thereby enhancing the operational efficiency and social image of power grid companies.

[0102] Based on the method described in the above embodiments, this embodiment will further describe it from the perspective of a reliability assessment system for flexible power distribution network structures. This system can be implemented as an independent entity or integrated into electronic devices, such as terminals.

[0103] Please see Figure 5 , Figure 5 This is a schematic diagram of a reliability assessment system for a flexible power distribution network structure provided in an embodiment of the present invention. The system includes:

[0104] The evaluation model construction module is used to construct a reliability evaluation model for a flexible distribution network structure. The reliability evaluation model includes a reliability index calculation model under normal operation of the distribution network and a reliability index calculation model under fault conditions. The evaluation model construction module is used to execute step S1.

[0105] The reliability index calculation model for the power distribution network under normal operating conditions includes:

[0106]

[0107] In the formula, R Operation The reliability of the distribution network under normal operating conditions; N is the total number of lines in the distribution network; M is the total number of nodes in the distribution network; S Line i S represents the amount of electricity transmitted by line i in the distribution network per unit time; Line-N i U represents the rated capacity of line i in the distribution network;j U is the phase voltage amplitude at node j; N j f is the rated phase voltage of node j; j f is the frequency of node j; N j Let be the rated frequency of node j.

[0108] The reliability index calculation model for distribution network under fault conditions includes:

[0109] R Supply =α·R Relay +(1-α)·R Recover ;

[0110] In the formula, R Supply R is a reliability indicator for distribution network under fault conditions. Relay To protect reliability; R Recover α represents the reliability of fault recovery; α is the weighting coefficient.

[0111] The protection reliability R Relay Calculate using the following formula:

[0112]

[0113] In the formula, t Trip The protection operation time after a distribution network fault occurs; t max Maximum protection duration; S Transformer The total load capacity of the area affected by the power outage after the protection action takes effect; S max This represents the total load of the distribution network.

[0114] The fault recovery reliability R Recover Calculate using the following formula:

[0115]

[0116] In the formula, t Recover The time required to complete load transfer after a distribution network fault occurs; Maximum load transfer time; S Recover For transferring load capacity; S out The total capacity of the 10kV and 0.4kV transformers in the power outage area; S represents the amount of electricity transmitted by line i in the distribution network per unit time after load transfer; Line-N i This represents the rated capacity of line i in the distribution network.

[0117] The simulation model building module is used to build a simulation model of a flexible power distribution network structure, and the simulation model building module is used to execute step S2.

[0118] The data acquisition module is used to acquire operating data under normal operating conditions and operating data under fault conditions of the distribution network through the simulation model. The data acquisition module is used to execute step S3.

[0119] The operating data of the distribution network under normal operating conditions include: the power transmitted by each line in the distribution network, the voltage amplitude of each node in the distribution network, and the frequency of each node in the distribution network;

[0120] The operational data under the fault operation status of the distribution network includes: the protection action time after the distribution network fault occurs, the total load capacity of the power outage area after the protection action takes effect, the time required to complete the load transfer after the distribution network fault occurs, and the total load capacity transferred.

[0121] The following steps are taken to obtain operational data of the flexible distribution network under fault conditions using the simulation model:

[0122] S301. Set fault points at different locations in the simulation model of the AC power grid;

[0123] S302. Simulate different types of faults at each fault point and obtain distribution network operation simulation data under the condition that different types of line faults occur at each fault point.

[0124] The index calculation module is used to calculate the reliability index of the distribution network under normal operating conditions based on the operating data of the distribution network under normal operating conditions; and to calculate the reliability index of the distribution network under fault conditions based on the operating data and reliability assessment model of the power grid under fault conditions. The index calculation module is used to execute step S4.

[0125] Additionally, please see Figure 6 , Figure 6 This is a schematic diagram of an electronic device provided in an embodiment of the present invention. The electronic device includes a processor and a memory. The processor and the memory are electrically connected. The electronic device includes a processor, a memory, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps in the aforementioned reliability assessment method for flexible power distribution network structures.

[0126] Those skilled in the art will understand that all or part of the steps in the various methods of the above embodiments can be implemented by instructions, which can be stored in a computer-readable storage medium and loaded and executed by a processor. Therefore, embodiments of the present invention provide a storage medium on which a computer program is stored, the computer program being executed by a processor to implement the above-described reliability assessment method for flexible power distribution network structures.

[0127] Generally, the computer instructions for implementing the method of the present invention can be carried on any combination of one or more computer-readable storage media. Non-transitory computer-readable storage media can include any computer-readable medium except for the signal itself, which is temporarily propagating.

[0128] Computer-readable storage media can be, for example, but not limited to, electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatuses, or devices, or any combination thereof. More specific examples (not an exhaustive list) of computer-readable storage media include: electrical connections having 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 thereof. In this invention, a computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with a system, apparatus, or device that executes instructions.

[0129] Computer program code for performing the operations of this invention can be written using one or more programming languages ​​or a combination thereof. These programming languages ​​include object-oriented programming languages ​​such as Java, Smalltalk, and C++, as well as conventional procedural programming languages ​​such as C or similar languages. In particular, Python, suitable for neural network computation, and platform frameworks based on TensorFlow, PyTorch, etc., can be used. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the case of remote computers, the remote computer can be connected to the user's computer via various types of networks, including local area networks (LANs) or wide area networks (WANs), or via an internet service provider.

[0130] Although embodiments of the present invention have been shown and described above, it should be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A reliability assessment method for a flexible power distribution network structure, characterized in that: The reliability assessment method for the flexible power distribution network structure includes: S1. Construct a reliability assessment model for a flexible distribution network structure. The reliability assessment model includes a reliability index calculation model under normal operating conditions and a reliability index calculation model under fault conditions. S2. Construct a simulation model of a flexible power distribution network structure; S3. Obtain operating data under normal operating conditions and operating data under fault conditions of the distribution network through the simulation model; S4. Calculate the reliability index of the distribution network under normal operating conditions based on the operating data and reliability assessment model. The reliability index of the distribution network under fault conditions is calculated based on the operating data and reliability assessment model. The reliability index calculation model for the power distribution network under normal operating conditions includes: ； In the formula, This refers to the reliability of the distribution network under normal operating conditions. This represents the total number of lines in the distribution network. This represents the total number of nodes in the distribution network. For lines in the distribution network The amount of electricity delivered per unit time; For lines in the distribution network Rated capacity; For nodes The phase voltage amplitude; For nodes The rated value of the phase voltage; For nodes The frequency; For nodes The rated frequency.

2. The reliability assessment method for a flexible power distribution network structure according to claim 1, characterized in that: The operating data of the distribution network under normal operating conditions include: the amount of electricity transmitted by each line in the distribution network per unit time, the voltage amplitude of each node in the distribution network, and the frequency of each node in the distribution network. The operational data under the fault operation status of the distribution network includes: the protection action time after the distribution network fault occurs, the total load capacity of the power outage area after the protection action takes effect, the time required to complete the load transfer after the distribution network fault occurs, and the total load capacity transferred.

3. The reliability assessment method for a flexible power distribution network structure according to claim 2, characterized in that: The reliability index calculation model for distribution network under fault conditions includes: ； In the formula, It is a reliability indicator for the distribution network under fault conditions; To protect reliability; To ensure reliable fault recovery; These are the weighting coefficients.

4. The reliability assessment method for a flexible power distribution network structure according to claim 3, characterized in that: The protection reliability Calculate using the following formula: ； In the formula, This refers to the protection operation time after a distribution network fault occurs; To protect the maximum duration of the action; The total load capacity of the area affected by the power outage after the protection action takes effect; This represents the total load of the distribution network.

5. The reliability assessment method for a flexible power distribution network structure according to claim 4, characterized in that: The reliability of fault recovery Calculate using the following formula: ； In the formula, The time required to complete load transfer after a distribution network fault occurs; Maximum load transfer time; To transfer load capacity; The total capacity of the 10kV and 0.4kV transformers in the power outage area; For the distribution network lines after load transfer The amount of electricity delivered per unit time; For lines in the distribution network Rated capacity.

6. The reliability assessment method for a flexible power distribution network structure according to claim 1, characterized in that: The following steps are taken to obtain operational data of the flexible distribution network under fault conditions using the simulation model: S301. Set fault points at different locations in the simulation model of the power distribution network; S302. Simulate different types of faults at each fault point and obtain the operation data of the distribution network under the condition that different types of line faults occur at each fault point.

7. A reliability assessment system for a flexible power distribution network structure, comprising: The evaluation model construction module is used to construct a reliability evaluation model for a flexible distribution network structure. The reliability evaluation model includes a reliability index calculation model under normal operation of the distribution network and a reliability index calculation model under fault conditions. The simulation model building module is used to build simulation models of flexible power distribution network structures. The data acquisition module is used to acquire operating data of the distribution network under normal operating conditions and operating data of the distribution network under fault conditions through the simulation model. The index calculation module is used to calculate the reliability index of the distribution network under normal operating conditions based on the operating data of the distribution network under normal operating conditions; and to calculate the reliability index of the distribution network under fault conditions based on the operating data and reliability assessment model of the power grid under fault conditions. The reliability index calculation model for the power distribution network under normal operating conditions includes: ； In the formula, This refers to the reliability of the distribution network under normal operating conditions. This represents the total number of lines in the distribution network. This represents the total number of nodes in the distribution network. For lines in the distribution network The amount of electricity delivered per unit time; For lines in the distribution network Rated capacity; For nodes The phase voltage amplitude; For nodes The rated value of the phase voltage; For nodes The frequency; For nodes The rated frequency.

8. A reliability assessment device for a flexible power distribution network structure, comprising a memory and a processor, wherein the memory is used to store computer program code and transmit the computer program code to the processor; The processor is configured to execute the reliability assessment method for the flexible power distribution network structure as described in any one of claims 1 to 6 according to instructions in the computer program code.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the reliability assessment method for flexible power distribution network structures as described in any one of claims 1 to 6.

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