Reliability evaluation method and system for flexible power distribution network structure

Abstract

A reliability evaluation method for a flexible power distribution network structure comprises the steps that a reliability evaluation model of the flexible power distribution network structure is constructed, and the reliability evaluation model comprises a reliability index calculation model in a normal operation state of a power distribution network and a reliability index calculation model in a fault state of the power distribution network; constructing a flexible power distribution network structure simulation model; acquiring operation data of the flexible power distribution network in a normal operation state and operation data of the flexible power distribution network in a fault state through the simulation model; calculating a reliability index of the power distribution network in the normal operation state according to the operation data of the power distribution network in the normal operation state and the reliability evaluation model; and calculating a 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. According to the design, the reliability of the flexible power distribution network structure can be comprehensively and accurately evaluated.

Description

Technical Field

[0001] The present invention relates to the technical field of power transmission and distribution, and in particular to a reliability assessment method and system for a flexible distribution network structure. Background Art

[0002] With the rapid development of the power industry and the continuous advancement of technology, the distribution system has gradually become more complex and flexible. On the one hand, the access of new power elements such as distributed power sources, energy storage devices, SOP, etc. makes the structure of the distribution system more complex and changeable; on the other hand, users have higher and higher requirements for the reliability and stability of power supply, requiring the distribution network to have stronger adaptive capabilities and fault recovery capabilities.

[0003] With the continuous growth of electricity demand and the increasing complexity of the power grid structure, the traditional distribution network structure can no longer meet the needs of modern power systems for high reliability, high flexibility and efficient operation. The modern distribution network structure introduces a flexible structure to improve the adaptability and flexibility of the distribution network, so as to better meet the development requirements of the future power industry. However, the existing distribution network power supply reliability analysis method is often difficult to fully and accurately reflect the performance of the high-reliability and high-flexibility flexible structure distribution system under complex working conditions; in addition, the existing technology also has certain limitations when processing large-scale data and scenarios with high real-time requirements. Based on the above problems, the present invention proposes a reliability analysis method based on a flexible distribution network structure. The method is based on the flexible distribution network structure and comprehensively considers a variety of different factors to achieve a quantitative evaluation of the power supply reliability of the distribution network under different working conditions, optimize the power supply reliability evaluation means of the distribution network, and enhance its flexible response capabilities under complex and changeable working conditions, providing strong technical support and decision-making basis for the design, operation and management of the distribution network. Summary of the invention

[0004] The purpose of the present invention is to overcome the problem that the existing distribution network power supply reliability analysis method in the prior art is difficult to fully and accurately reflect the reliability of the flexible structure distribution system under complex working conditions, and to provide a reliability assessment method and system for a flexible distribution network structure.

[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 a flexible distribution network structure, comprising:

[0007] S1. Construct a reliability evaluation model for a flexible distribution network structure, wherein 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 condition of the distribution network;

[0008] S2, construct a simulation model of the flexible distribution network structure;

[0009] S3. Obtaining operation data of the flexible distribution network in a normal operating state and operation data of the flexible distribution network in a fault state through the simulation model;

[0010] S4. Calculate the reliability index of the distribution network under normal operation according to the operation data of the distribution network under normal operation and the reliability evaluation model;

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

[0012] The operating data of the distribution network in a normal operating state includes: 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 operating data under the distribution network fault operation state 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 under the normal operation state of the distribution network includes:

[0015]

[0016] In the formula, R Operation is the reliability of the distribution network under normal operation; 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 is the amount of electricity transmitted by line i in the distribution network per unit time; S Line-N i is the rated capacity of line i in the distribution network; U j is the phase voltage amplitude of node j; U N j is the phase voltage rating of node j; f j is the frequency of node j; f N j is the rated frequency of node j.

[0017] The reliability index calculation model under the fault state of the distribution network includes:

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

[0019] In the formula, R Supply is the reliability index of the distribution network under fault conditions; R Relay To protect reliability; RRecover is the fault recovery reliability; α is the weight coefficient.

[0020] The protection reliability R Relay Calculated according to the following formula:

[0021]

[0022] Where, t Trip is the protection action time after the distribution network fault occurs; t max The maximum protection action time; S Transformer S is the total load capacity of the blackout area after the protection action takes effect; max is the total load of the distribution network.

[0023] The failure recovery reliability R Recover Calculated according to the following formula:

[0024]

[0025] Where, t Recover It is the time required to complete load transfer after a distribution network failure occurs; The maximum load transfer time; S Recover is the transfer load capacity; S out The total capacity of the 10kV transformer and 0.4kV transformer in the blackout area; is the amount of electricity transmitted by line i in the distribution network per unit time after load transfer; S Line-N i is the rated capacity of line i in the distribution network.

[0026] The following steps are used to obtain the operation data of the flexible distribution network under the fault operation state through the simulation model:

[0027] S301, setting fault points at different locations of the simulation model of the AC power grid;

[0028] S302: Simulate different types of faults at each fault point to obtain operation data of the distribution network when different types of line faults occur at each fault point.

[0029] In a second aspect, the present invention provides a reliability assessment system for a flexible distribution network structure, comprising:

[0030] An evaluation model building module is used to build a reliability evaluation model of a flexible distribution network structure, wherein 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 condition of the distribution network;

[0031] A simulation model building module is used to build a simulation model of the flexible distribution network structure;

[0032] A data acquisition module, used to acquire operation data of the distribution network in a normal operating state and operation data of the distribution network in a fault state through the simulation model;

[0033] 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.

[0034] In a third aspect, the present invention provides an evaluation device, 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;

[0035] The processor is used to execute the above-mentioned reliability assessment method of the flexible distribution network structure according to the instructions in the computer program code.

[0036] In a fourth aspect, the present invention provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps in the reliability assessment method of the above-mentioned flexible distribution network structure.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] 1. In a reliability assessment method for a flexible distribution network structure of the present invention, an assessment index system for a flexible distribution network structure is established, including reliability indicators under normal operating conditions of the distribution network and reliability indicators under fault conditions of the distribution network. Among them, the calculation of the reliability index under normal operating conditions of the distribution network integrates the flexible line load rate, flexible voltage stability, and flexible frequency control accuracy parameters for calculation; the reliability index under the fault state of the distribution network integrates the protection reliability and fault recovery reliability parameters for calculation, accurately reflecting the performance of the distribution network under different working conditions, and providing more accurate data support for subsequent quantitative analysis and optimization. Therefore, this design establishes an assessment index system for a flexible distribution network structure, accurately reflecting the performance of the distribution network under different working conditions, and providing more accurate data support for subsequent quantitative analysis and optimization.

[0039] 2. In a reliability assessment method for a flexible distribution network structure of the present invention, the reliability index under the fault state of the distribution network comprehensively evaluates the protection reliability and power supply restoration reliability, and comprehensively considers the network topology and load demand. Among them, the protection reliability comprehensively considers the distributed power supply control strategy, the protection action time, and the fault identification, and quantifies the protection action of the distribution network structure by the flexible protection action speed and the flexible transformer capacity in the power outage area, which can accurately and quickly reflect the response speed and impact range of the power grid at the initial stage of the fault; the power supply restoration reliability is reflected by the flexible load transfer speed and the transfer load capacity, which directly determines the recovery speed and efficiency of the power grid after the fault; and, in this method, the weights of protection reliability and power supply restoration reliability are allocated according to actual needs, which can more accurately judge the performance of the flexible distribution network structure, and then provide 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 the reliability index under the fault state of the distribution network, and allocates the weights of protection reliability and power supply restoration reliability according to actual needs. The evaluation results can comprehensively and accurately reflect the real situation of the flexible distribution network structure.

[0040] 3. In the reliability assessment method of a flexible distribution network structure of the present invention, a simulation model of the flexible distribution network structure is used to accurately simulate the reliability performance of the flexible distribution network in a complex and changeable operating environment; at the same time, when building the simulation model, not only the basic fault state simulation is considered, but also the different fault locations, fault types, and the impact time caused by different faults are refined, so that the simulation results are closer to the actual operation of the distribution network. Therefore, the simulation results of this design are closer to the actual operation of the distribution network. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a flow chart of a reliability assessment method of a flexible distribution network structure provided by an embodiment of the present invention.

[0042] Figure 2 It is a topological diagram of three flexible connection structures of the distribution network provided by the embodiments of the present invention.

[0043] Figure 3 It is a topological diagram of the distribution network simulation model based on three different flexible connection structures.

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

[0045] Figure 5 It is a structural diagram of a reliability assessment system for a flexible distribution network structure.

[0046] Figure 6 It is a structural schematic diagram of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0047] The present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0048] With the advancement of power technology, modern distribution network structures have introduced flexible structures to improve the adaptability and flexibility of distribution networks. Flexible distribution networks have achieved efficient scheduling of power flows and immediate response to grid changes with their excellent flexibility, adjustable network structure, and advanced intelligent control technology. At the same time, with the intelligent development of grid technology, grid "self-healing" technology enables modern grids to achieve self-monitoring, self-diagnosis, and self-repair, thereby ensuring the stable, reliable, and safe operation of the grid. For modern grids that have introduced flexible structures and intelligent control technologies, traditional reliability indicators have been difficult to fully evaluate their performance.

[0049] In order to solve the above technical problems, the present invention provides a more accurate, comprehensive and efficient flexible distribution network power supply reliability assessment method to cope with the increasing complexity and flexibility requirements of modern distribution systems, such as Figure 1 As shown, Figure 1 It is a flow chart of a reliability assessment method of a flexible distribution network structure provided by an embodiment of the present invention, the method comprising steps S1 to S4;

[0050] S1. Construct a reliability assessment model for the flexible distribution network structure;

[0051] 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 condition of the distribution network.

[0052] In this embodiment, 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 condition of the distribution network.

[0053] The power supply reliability of the flexible distribution network under normal operation is mainly measured by the flexible line load rate, flexible voltage stability and flexible frequency control accuracy. Specifically, the reliability index calculation model under normal operation of the distribution network includes:

[0054]

[0055] In the formula, R Operation is the reliability of the distribution network under normal operation; 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 is the amount of electricity transmitted by line i in the distribution network per unit time;

[0056] S Line-Ni is the rated capacity of line i in the distribution network. The rated capacity of a line refers to the capacity of the line that can continue to work for a long time under rated working conditions (such as rated voltage, rated current, etc.) without exceeding its design limit. It is an important parameter determined during line design and manufacturing. The rated capacity of the line is a fixed value. j is the phase voltage amplitude of node j; U N j is the phase voltage rating of node j; f j is the frequency of node j; f N j is the rated frequency of node j.

[0057] When the distribution network is operating normally, in order to comprehensively evaluate the reliability of the distribution network under normal operating conditions, we mainly focus on three core indicators: flexible line load rate, flexible voltage stability and flexible frequency control accuracy. Among them, the flexible line load rate reflects the utilization degree of the load. Flexible voltage stability reflects the ability of voltage to maintain stability. The flexible frequency control accuracy reveals the accuracy of frequency control. The three indicators of flexible line load rate, flexible voltage stability and flexible frequency control accuracy together constitute the reliability evaluation system of the distribution network under normal operation, helping us to monitor the operation status of the power grid in real time and ensure that the distribution network can supply power stably and reliably.

[0058] The reliability index calculation model under the fault state of the distribution network includes:

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

[0060] In the formula, R Supply is the reliability index of the distribution network under fault conditions; R Relay To protect reliability; R Recover is fault recovery reliability; α is a weight 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 actual conditions. In this embodiment, the weight α is 0.6.

[0061] When a distribution network fails, the reliability of its protection action and fault recovery capability become the key to measuring its power supply reliability. Therefore, the reliability index of the distribution network under fault conditions is quantified into two parts, namely protection reliability and fault recovery reliability. Especially for distribution networks containing distributed power sources, it is necessary to consider the distributed power control strategy, fault characteristics, protection action time, and whether the fault identification is correct, and quantitatively analyze the protection reliability of the distribution network containing distributed power sources; by analyzing all possible fault events and the consequences of fault events on the distribution network system, the consequences of fault modes are analyzed, and then the fault recovery reliability of the distribution network containing distributed power sources is quantitatively analyzed.

[0062] When a line fails, ensuring that the protection device can accurately and quickly cut off the faulty line and effectively isolate the power outage area is a prerequisite for implementing fault recovery work. For protection reliability, we use R Relay To represent the protection reliability of the distribution network, we consider the flexible protection action speed and the flexible transformer capacity in the blackout area. To quantify the protection action speed, To quantify the capacity of flexible transformers in the blackout area, these two parameters can quickly reflect the response speed and impact range of the power grid at the initial stage of a fault.

[0063] The protection reliability R Relay Calculated according to the following formula:

[0064]

[0065] Specifically, in terms of protection reliability R Relay In the calculation formula, taking the 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, actual ≥ 0.6s are replaced by 0.6s); t Trip is the protection action time after the distribution network fault occurs, t max is the maximum protection action time, t max Take 0.6 seconds for calculation, That is to Trip Normalization processing, S Transformer S is the total load capacity of the power outage area after the protection action takes effect. max is the total load of the distribution network, That is to S Transformer Normalization processing.

[0066] After the fault is automatically removed by protection action, there will be a power outage in some areas. The fault recovery strategy equipped by the distribution network will restore part or all of the power outage load through load transfer. For fault recovery reliability, we quantitatively analyze the reliability of fault recovery by flexible load transfer speed, transfer load capacity, and flexible line overload warning capability. We use R Recover To represent the fault recovery reliability of the distribution network, we use To quantify the flexible load transfer speed, To quantify the transfer load capacity, To quantify the overload of flexible lines, these three parameters directly reflect the speed and efficiency of the power grid's recovery after a fault. In addition, we also need to consider additional factors such as the overload warning capability of flexible lines to more comprehensively evaluate the impact of faults on the overall power supply reliability of the power grid. The reliability indicators of the distribution network under fault conditions provide us with a basis for decision-making to more effectively respond to power grid faults and ensure the continuity and stability of power supply.

[0067] The failure recovery reliability R Recover Calculated according to the following formula:

[0068]

[0069] Where, t Recover It is the time required to complete load transfer after a distribution network fault occurs. For modern distribution networks equipped with self-healing, the flexible load transfer speed is quantified as the load transfer time after the protection action. Specifically, if there is no distributed power source in the area to be restored, the time required to complete the load transfer is 0.3 seconds. If there is a distributed power source in the area to be restored, the time required to complete the load transfer needs to add the action time of the anti-islanding protection by 2 seconds. is the maximum load transfer time, which is 3.2 seconds. That is to Recover Normalization processing; S Recover S is the transfer load capacity, that is, the sum of the transformer capacities that resume power supply after a power outage; out is the total capacity of the transformers in the area where the power outage occurred due to the fault, That is to S Recover Normalization processing; is the amount of electricity transmitted by line i in the distribution network per unit time after load transfer; S Line-N i is the rated capacity of line i in the distribution network.

[0070] In this embodiment, when a fault occurs at different locations of the flexible distribution network, its protection action time and load transfer time will be different, so its protection reliability and fault recovery reliability will also be different, that is, the reliability index of the distribution network under fault conditions in different fault scenarios is different. Through this method, the power supply reliability of the flexible distribution network under different fault scenarios can be calculated.

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

[0072]

[0073]

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

[0075] The evaluation indicators in Table 1 cover the parameters under normal operating conditions and emphasize the key factors under fault conditions. They aim to more accurately reflect the reliability level of the flexible distribution network under different operating conditions, provide a scientific basis for the optimal 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 flexible distribution network structure simulation model.

[0077] S3. Obtaining operation data of the distribution network in a normal operating state and operation data of the distribution network in a fault state through the simulation model.

[0078] In this embodiment, the following steps are performed to obtain the operation data of the flexible distribution network in a fault operation state through the simulation model:

[0079] S201, setting fault points at different locations of the simulation model of the AC power grid;

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

[0081] S4. Calculate the reliability index of the distribution network under normal operation according to the operation data of the distribution network under normal operation and the reliability evaluation model;

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

[0083] After calculating the reliability index of the distribution network under normal operation and the reliability index of the distribution network under different fault conditions, corresponding fault response measures can be put forward according to the reliability index of the distribution network under different fault conditions; at the same time, the reliability index of multiple distribution networks with different structures under normal operation and the reliability index of the distribution network under different fault conditions can also be calculated, and the distribution networks with different structures can be compared and selected according to the calculation results, so as to provide a scientific basis for the optimal design, operation management and fault response of the power grid.

[0084] An embodiment of the present invention provides a reliability assessment method for a flexible distribution network structure. The method includes building a reliability index quantitative calculation model under normal operating conditions and fault conditions of the distribution network based on a flexible interconnected structure, and comprehensively considering various factors such as structure, equipment performance, and load demand, so as to achieve dynamic and accurate assessment and optimization of the distribution network under various operating conditions, aiming to overcome the limitations of the existing technology, improve the power supply reliability and flexibility of the distribution network, and better adapt to the development needs of the future power industry.

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

[0086] We selected three distribution networks with different flexible connection structures and used the above-mentioned reliability assessment method for the flexible distribution network structure to calculate the reliability indexes of the three distribution networks with different flexible connection structures under normal operation and under fault conditions, and evaluated and compared the reliability of distribution networks with different flexible connection structures based on the calculation results. Figure 2 As shown, Figure 2 The topologies of three flexible connection structures of distribution networks are given, namely, the single-end flexible closed-loop structure between feeders, the multi-end flexible interconnection structure between ring networks, and the mesh-type multi-end flexible interconnection structure.

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

[0088] We further set the fault and penetration rate of the distribution network, such as Figure 4 As shown, Figure 4 The figure is a schematic diagram of the simulation model of a flexible distribution network with distributed generation. We set five line fault injection points f1-f5 on different lines of the simulation model. Then we set the distributed generation penetration rate. The distributed generation is connected to each substation and distribution station of 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 calculation formula for the distributed generation penetration rate of the distribution network is as follows:

[0089]

[0090] Where Permeability is the penetration rate of distributed power generation in the distribution network, S PV is the capacity of distributed generation connected to the distribution network, S Load It is the capacity of the load connected to the distribution network.

[0091] We simulate and analyze the reliability of the power supply of the flexible distribution network under normal operation, as shown in Table 2. Table 2 shows the reliability of the flexible distribution network containing distributed power sources under three flexible connection structures under normal operation. Load Taking 3MW, the penetration rates of distributed generation are 0%, 20%, 40%, 60%, 80% and 100% respectively.

[0092]

[0093] Table 2 Reliability of distribution network under normal operation

[0094] It can be seen from the above table that when the penetration rate of distributed power sources is 0%, the power supply reliability of the distribution network is the highest, followed by when the penetration rate of distributed power sources is 40%, and when the penetration rate of distributed power sources is 100%, the power supply reliability of the distribution network is the lowest; 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 multi-terminal flexible interconnection structure between ring networks, and the lowest reliability is the single-terminal flexible interconnection structure between feeders.

[0095] From the above analysis, it can be seen that the single-end flexible closed-loop structure between feeders can adjust the active and reactive power of the converters and then adjust the active and reactive power of the two feeders, which has a significant effect on alleviating the terminal voltage increase and line overload, and can significantly improve the power supply reliability of the distribution network. The multi-terminal flexible connection structure between ring networks is not much different from the single-end flexible closed-loop structure between feeders. Both can adjust the active and reactive power of the converters and then adjust the active and reactive power of the two feeders, thereby alleviating the problem of terminal voltage increase and line overload. Therefore, the power supply reliability of the multi-terminal flexible connection structure between ring networks is similar to that of the single-end flexible closed-loop structure between feeders. The mesh-type multi-terminal flexible interconnection structure has more diverse power adjustment paths and has flexible adjustment means to alleviate the problem of terminal voltage increase and line overload. The mesh-type multi-terminal flexible interconnection structure has a certain improvement in power supply reliability compared to the multi-terminal flexible connection structure between ring networks.

[0096] We then use 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 in the distribution network containing distributed power sources under three different flexible connection structures, where the penetration rates of distributed power sources are 0%, 20%, 40%, 60%, 80% and 100% respectively.

[0097]

[0098] Table 3 Reliability of distribution network under fault conditions

[0099] As can be seen from the above table, when the penetration rate of distributed power sources is 0% and the fault location is f3, the power supply reliability of the distribution network is the highest. When the penetration rate of distributed power sources is 0%, the reliability at the 5 fault locations is high. Overall, no matter how much the penetration rate of distributed power sources is, the power supply reliability at the fault location f3 is high. When the penetration rate of distributed power sources is 20% and the fault location is f5, the power supply reliability of the distribution network is the lowest, and the power supply reliability at the fault locations f1 and f5 is low. 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 multi-terminal flexible interconnection structure between ring networks, and the lowest reliability is the single-terminal flexible interconnection structure between feeders.

[0100] From the above analysis, it can be seen that for the power supply reliability of the distribution network during faults, the use of a single-end flexible closed-loop structure between feeders still transfers the power outage load to the opposite feeder, and the power supply reliability has not been significantly improved. Compared with the single-end flexible closed-loop structure between feeders, the use of a multi-terminal flexible interconnection structure between ring networks has an additional transfer path, so there are fewer line overloads and improved power supply reliability. Compared with the multi-terminal flexible interconnection structure between ring networks, the use of a mesh-type multi-terminal flexible interconnection structure has more diverse load transfer paths, which can be transferred through ordinary interconnection switches or through SOPs, so there are fewer line overloads and improved power supply reliability.

[0101] The present invention aims to achieve a quantitative evaluation of the power supply reliability of the distribution network under normal and fault conditions by comprehensively considering multiple factors such as load demand, network topology, equipment status, and fault simulation, and to propose optimization suggestions and fault response measures based on the evaluation results. This will not only help improve the fault response capability and overall operating efficiency of the distribution network, but also significantly reduce the failure rate and power outage time, provide users with a more stable and reliable power supply, and thus improve the operating benefits and social image of power grid companies.

[0102] According to the method described in the above embodiment, this embodiment will be further described from the perspective of a reliability assessment system for a flexible distribution network structure. The system can be implemented as an independent entity or integrated in an electronic device, such as a terminal.

[0103] See also Figure 5 , Figure 5 1 is a schematic diagram of a structure of a reliability assessment system for a flexible distribution network structure provided by an embodiment of the present invention, the system comprising:

[0104] An evaluation model construction module is used to construct a reliability evaluation model of a flexible distribution network structure, wherein 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 condition of the distribution network, and the evaluation model construction module is used to execute step S1;

[0105] The reliability index calculation model under the normal operation state of the distribution network includes:

[0106]

[0107] In the formula, R Operation is the reliability of the distribution network under normal operation; 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 is the amount of electricity transmitted by line i in the distribution network per unit time; S Line-N i is the rated capacity of line i in the distribution network; Uj is the phase voltage amplitude of node j; U N j is the phase voltage rating of node j; f j is the frequency of node j; f N j is the rated frequency of node j.

[0108] The reliability index calculation model under the fault state of the distribution network includes:

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

[0110] In the formula, R Supply is the reliability index of the distribution network under fault conditions; R Relay To protect reliability; R Recover is the fault recovery reliability; α is the weight coefficient.

[0111] The protection reliability R Relay Calculated according to the following formula:

[0112]

[0113] Where, t Trip is the protection action time after the distribution network fault occurs; t max The maximum protection action time; S Transformer S is the total load capacity of the blackout area after the protection action takes effect; max is the total load of the distribution network.

[0114] The failure recovery reliability R Recover Calculated according to the following formula:

[0115]

[0116] Where, t Recover It is the time required to complete load transfer after a distribution network failure occurs; The maximum load transfer time; S Recover is the transfer load capacity; S out The total capacity of the 10kV transformer and 0.4kV transformer in the blackout area; is the amount of electricity transmitted by line i in the distribution network per unit time after load transfer; S Line-N i is the rated capacity of line i in the distribution network.

[0117] A simulation model construction module, used to construct a flexible distribution network structure simulation model, and the simulation model construction module is used to perform the step S2;

[0118] A data acquisition module, used for acquiring operation data of the distribution network in a normal operating state and operation data of the distribution network in a fault state through the simulation model, wherein the data acquisition module is used for executing step S3;

[0119] The operating data of the distribution network in a normal operating state includes: 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 operation data under the distribution network fault operation state includes: protection action time after the distribution network fault occurs, total load capacity of the blackout area after the protection action takes effect, time required to complete load transfer after the distribution network fault occurs, and total load capacity transferred;

[0121] The following steps are used to obtain the operation data of the flexible distribution network under the fault operation state through the simulation model:

[0122] S301, setting fault points at different locations of 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 when 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 according to the operating data of the distribution network under normal operating conditions; calculate the reliability index of the distribution network under fault conditions according to the operating data of the distribution network under fault conditions and the reliability evaluation model. The index calculation module is used to execute the step S4.

[0125] Also, see Figure 6 , Figure 6 1 is a structural diagram of an electronic device provided in an embodiment of the present invention, wherein the electronic device includes a processor and a memory. The processor is electrically connected to the memory. The electronic device includes a processor, a memory, and a computer program stored in the memory and executable on the processor, and the processor implements the steps in the reliability assessment method of the flexible distribution network structure when executing the computer program.

[0126] Those skilled in the art can understand that all or part of the steps in the various methods of the above embodiments can be completed by instructions, which can be stored in a computer-readable storage medium and loaded and executed by a processor. To this end, an embodiment of the present invention provides a storage medium, on which a computer program is stored, and when the computer program is executed by the processor, the reliability assessment method of the above flexible distribution network structure is implemented.

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

[0128] Computer-readable storage media, for example, may be, but are not limited to, electrical, magnetic, optical, electromagnetic, infrared or semiconductor systems, devices or devices, or any combination thereof. More specific examples of computer-readable storage media (a non-exhaustive list) include: an electrical connection with one or more conductors, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof. In the present invention, a computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in conjunction with a system, device or device for executing instructions.

[0129] One or more programming languages ​​or their combinations can be used to write computer program codes for performing the operation of the present invention. These programming languages ​​include object-oriented programming languages, such as Java, Smalltalk, C++, and also include conventional procedural programming languages, such as C language or similar programming languages. In particular, Python language suitable for neural network calculations and platform frameworks based on TensorFlow, PyTorch, etc. can be used. The program code can be executed completely on the user's computer, partially on the user's computer, as an independent software package, partially on the user's computer and partially on the remote computer, or completely on the remote computer or server. In the case of a remote computer, the remote computer can be connected to the user's computer through various types of networks, including a local area network (LAN) or a wide area network (WAN), or an Internet connection is performed through an Internet service provider.

[0130] Although the 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 limitations on the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A reliability assessment method for a flexible distribution network structure, characterized in that: The reliability assessment method of the flexible distribution network structure includes: S1. Construct a reliability evaluation model for a flexible distribution network structure, wherein 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 condition of the distribution network; S2, construct a simulation model of the flexible distribution network structure; S3. Acquiring operation data of the distribution network in a normal operating state and operation data of the distribution network in a fault state through the simulation model; S4. Calculate the reliability index of the distribution network under normal operation according to the operation data of the distribution network under normal operation and the reliability evaluation model; The reliability index of the distribution network under fault condition is calculated based on the operating data and reliability evaluation model under the distribution network fault condition.

2. The reliability assessment method of a flexible distribution network structure according to claim 1, characterized in that: The operating data of the distribution network in normal operation state includes: 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 operating data under the distribution network fault operation state 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 of a flexible distribution network structure according to claim 2 is characterized in that: The reliability index calculation model under the normal operation state of the distribution network includes: In the formula, R Operation is the reliability of the distribution network under normal operation; 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 is the amount of electricity transmitted by line i in the distribution network per unit time; S Line-N i is the rated capacity of line i in the distribution network; U j is the phase voltage amplitude of node j; U N j is the phase voltage rating of node j; f j is the frequency of node j; f N j is the rated frequency of node j.

4. The reliability assessment method of a flexible distribution network structure according to claim 2 is characterized in that: The reliability index calculation model under the fault state of the distribution network includes: R Supply =α·R Relay +(1-a)·R Recover ; In the formula, R Supply is the reliability index of the distribution network under fault conditions; R Relay To protect reliability; R Recover is the fault recovery reliability; α is the weight coefficient.

5. The reliability assessment method of a flexible distribution network structure according to claim 4 is characterized in that: The protection reliability R Relay Calculated according to the following formula: In the formula, t Trip is the protection action time after the distribution network fault occurs; t max The maximum time for protection action; S Transformer S is the total load capacity of the blackout area after the protection action takes effect; max is the total load of the distribution network.

6. The reliability assessment method of a flexible distribution network structure according to claim 5 is characterized in that: The failure recovery reliability R Recover Calculated according to the following formula: In the formula, t Recover It is the time required to complete load transfer after a distribution network failure occurs; The maximum load transfer time; S Recover is the transfer load capacity; S out is the total capacity of 10kV transformer and 0.4kV transformer in the power outage area; S' Line i is the amount of electricity transmitted by line i in the distribution network per unit time after load transfer; S Line-N i is the rated capacity of line i in the distribution network.

7. The reliability assessment method of a flexible distribution network structure according to claim 1 is characterized in that: The following steps are used to obtain the operation data of the flexible distribution network under the fault operation state through the simulation model: S301, setting fault points at different locations of the simulation model of the AC power grid; S302: Simulate different types of faults at each fault point to obtain operation data of the distribution network when different types of line faults occur at each fault point.

8. A reliability assessment system for a flexible distribution network structure, comprising: An evaluation model building module is used to build a reliability evaluation model of a flexible distribution network structure, wherein 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 condition of the distribution network; A simulation model building module is used to build a simulation model of the flexible distribution network structure; A data acquisition module, used to acquire operation data of the distribution network in a normal operating state and operation data of the distribution network in a fault state through the simulation model; The index calculation module is used to calculate the reliability index of the distribution network under normal operating conditions according to the operating data of the distribution network under normal operating conditions; and calculate the reliability index of the distribution network under fault conditions according to the operating data of the power grid under fault conditions and the reliability evaluation model.

9. A reliability assessment device for a flexible distribution network structure, comprising a memory and a processor, wherein the memory is used to store a computer program code and transmit the computer program code to the processor; The processor is used to execute the reliability assessment method of the flexible distribution network structure as described in any one of claims 1 to 7 according to the instructions in the computer program code.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the reliability assessment method for a flexible distribution network structure according to any one of claims 1 to 7 is implemented.

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