N-1 safety analysis method for distribution network based on minimum isolation region information array
By describing the switch and transformer information within the distribution network feeder using the minimum isolation area information array, the total amount of downstream load to be transferred and the switch carrying capacity of the transfer path are determined. This solves the problem of insufficient identification of weak links in the existing N-1 analysis of the distribution network, and realizes fast and accurate N-1 safety analysis and power restoration of the distribution network.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- QUANZHOU POWER SUPPLY COMPANY OF STATE GRID FUJIAN ELECTRIC POWER
- Filing Date
- 2022-09-05
- Publication Date
- 2026-06-23
AI Technical Summary
Existing N-1 analysis methods for distribution networks fail to accurately reflect the actual power transfer capacity and power supply reliability of the distribution network, resulting in false alarms and omissions in the perception of weak links, and making it impossible to perceive the operating status of the distribution network in real time.
A method based on the minimum isolation area information matrix is adopted to describe the switch and transformer information in the minimum isolation area of the distribution network feeder, determine the total load to be transferred downstream of the fault, describe the active power margin that the switches in the transfer path can carry through the load transfer path and the switch carrying capacity information matrix, and finally compare the minimum margin information matrix with the total load to be transferred to realize the analysis of the power supply restoration status downstream of the fault area.
It can quickly perform N-1 security analysis on the distribution network, identify the minimum isolation area and weak link that does not meet N-1, meet the needs of real-time online calculation and analysis on site, and improve the power supply reliability and security of the distribution network.
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Figure CN115333095B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of online rapid analysis of the operation safety of distribution networks, and specifically relates to an N-1 safety analysis method for distribution networks based on a minimum isolation area information array. Background Technology
[0002] With rapid economic development, people's demands for the continuity, security, and stability of power supply are constantly increasing. As a power supply network serving demand-side users, the rational planning and safe operation of the distribution network are of great significance for improving power supply reliability.
[0003] N-1 analysis of power grids is an important means of assessing the safety risks of power grid operation. It primarily refers to the ability of other equipment in a power grid to maintain normal power supply even when one piece of equipment fails. Transmission networks are designed and operate in a closed loop. The N-1 analysis in static security analysis assumes that when one piece of equipment in the grid, such as a line, transformer, or switch, fails, other equipment can maintain normal power supply through the action of protection devices and automatic safety devices. If the affected area can maintain normal power supply after equipment failure or maintenance shutdown, then the power grid meets the N-1 requirement; otherwise, if the affected area cannot restore normal power supply, then the power grid does not meet the N-1 requirement after equipment failure or maintenance shutdown.
[0004] The N-1 analysis for closed-loop design and open-loop operation of distribution networks differs from that of transmission networks. When distribution network equipment fails or is taken out of service for maintenance, power restoration to affected areas requires the operation of devices such as tie switch closing and substation outgoing line switch reclosing. Current distribution network N-1 analysis primarily focuses on scenarios assuming a substation outgoing line fault leading to a complete power outage along the feeder. This extreme case analysis fails to accurately reflect the actual power transfer capacity and reliability of the distribution network, and may result in false alarms and missed alarms regarding weak points in the distribution network.
[0005] In summary, researching the N-1 security analysis method for distribution networks, real-time sensing of the operation status of distribution networks, and extrapolation and prediction of the future evolution trend of distribution networks are of great practical significance. Summary of the Invention
[0006] The purpose of this invention is to provide a method for N-1 security analysis of distribution networks based on the minimum isolation area information array. This method is beneficial for convenient and quick implementation of N-1 security analysis of distribution networks.
[0007] To achieve the above objectives, the technical solution adopted by this invention is: an N-1 security analysis method for distribution networks based on a minimum isolation region information array, comprising:
[0008] Establish a minimum isolation area information matrix to describe the switch and transformer information within the minimum isolation area of all feeders in the distribution network;
[0009] Establish a real-time load information matrix for the minimum isolation zone to determine the total load to be transferred downstream of the fault;
[0010] Establish a load transfer path switch information matrix and a switch carrying capacity information matrix to describe the active power margin that switches in the transfer path can carry.
[0011] A minimum margin information matrix is established, and the minimum margin information matrix is compared with the total load to be transferred to achieve the analysis of the downstream power supply status of the fault area.
[0012] Furthermore, the minimum isolation area is defined as the connected area in a power distribution feeder that is bounded by an isolation device and contains no other isolation devices. The minimum isolation area is the smallest unit for fault isolation, and the isolation area is the same for any device within it that fails.
[0013] A Minimum Isolation Area Information Matrix (MIAM) is established to describe the switch and transformer information within the minimum isolation area of all feeders in the distribution network. Specifically:
[0014]
[0015] In the formula, each row represents all the minimum isolation regions on a feeder; MA ij This is the information for the j-th minimum isolation zone on the i-th feeder. If the minimum isolation zone does not exist, the value is -1; i = 1, 2, ..., n, where n is the number of feeders in the distribution network; j = 1, 2, ..., m, where m is the maximum number of minimum isolation zones contained in the feeder.
[0016]
[0017] In the formula, the first row represents the switch information contained in the minimum isolation zone, and the second row represents the distribution transformer information contained in the minimum isolation zone; ma ij,1k This represents the unique identifier of the k-th switch in the j-th minimum isolation region on the i-th feeder; if the switch does not exist, it is represented by -1; ma ij,2k This represents the unique identifier of the k-th transformer in the j-th minimum isolation region on the i-th feeder. If the transformer does not exist, it is represented by -1; k = 1, 2, ..., p, where p is the minimum isolation region MA. ij The maximum number of switches and distribution transformers contained therein.
[0018] Furthermore, a minimum isolation zone real-time load information matrix (RLIM) is established to describe the total active power of the real-time load within the minimum isolation zone of all feeders in the distribution network, specifically as follows:
[0019]
[0020]
[0021] In the formula, RL ij MA is the j-th minimum isolation region on the i-th feeder. ij The real-time total active power, which is determined by MA ij The real-time active power of the transformers contained within is determined, in kW; if the minimum isolation zone does not exist, the value is -1; P(ma ij,2k ) is a distribution transformer ma ij,2k Real-time active power;
[0022] When a fault occurs, power supply to the upstream area is restored through the reclosing of the substation outgoing circuit breaker. If there is no tie switch in the downstream area, it indicates that the fault occurred on a branch line, and power supply cannot be restored downstream, thus failing to meet N-1. If there is a tie switch in the downstream area, but it is under maintenance or faulty and cannot be used normally, power supply to the downstream area also cannot be restored, failing to meet N-1. If there is a tie switch in the downstream area and it is operating normally, power supply to the fault area is restored by closing the tie switch. The total load to be transferred is determined by the real-time total load power of the minimum isolation area downstream of the fault, specifically:
[0023]
[0024] In the formula, TLBT ij MA is the j-th minimum isolation region on the i-th feeder. ij The total downstream load awaiting transfer during a fault, in kW; RL iw For MA ij The real-time total active power of the downstream minimum isolation zone; w = a, a+1, ..., h, where h is the maximum active power per unit area (MA). ij The minimum number of downstream isolation zones, where a is MA ij The smallest isolation zone downstream is numbered.
[0025] Furthermore, starting from the tie switch, based on the distribution network topology, the search proceeds in reverse along the power flow until the fault area and the substation outgoing circuit breaker are reached. The area traversed constitutes a load transfer path. A load transfer path switch information matrix (LTSM) is established to describe the switch information in all transfer paths downstream of the fault, specifically:
[0026]
[0027] In the formula, each row contains switching information for a load transfer path, LT dcLet be the unique identifier of the c-th switch in the d-th load transfer path, where d = 1, 2, ..., f, f is the number of paths for load transfer downstream of the fault, and c = 1, 2, ..., e, e is the maximum number of switches included in all load transfer paths. If LT dc If it does not exist, use -1 to represent it;
[0028] A Switch Capacity Information Matrix (SCIM) is established to describe the active power margin that switches in the power transfer path can carry. Specifically:
[0029]
[0030] SC dc =S(LT) dc )-P(LT dc (8)
[0031] In the formula, each row represents the active power margin that the switches in a load transfer path can carry, S(LT). dc ) is the switch LT dc Rated active power, P(LT) dc ) is the switch LT dc Real-time active power; SC dc For switch LT dc The active power margin that can be carried is expressed in kW. If the switch is not present, it is represented by -1.
[0032] Furthermore, the load transfer process is limited by the minimum carrying capacity margin in the transfer path; a minimum carrying capacity information matrix (MMIM) is established to describe the active power margin that switches in each transfer path can carry, specifically:
[0033] MMIM = [MM1 MM2 … MM] d …MM f (9)
[0034] MM d =min(SC) d1 ,SC d2 ,…,SC dc ,…,SC de (10)
[0035] In the formula, MM d Let d be the minimum value in the d-th row of the switch load-bearing capacity information matrix SCIM, and min() is used to take the minimum value;
[0036] If the downstream loads affected by the fault can have their power restored through a joint power transfer path, then the N-1 analysis is also satisfied; specifically:
[0037]
[0038] If formula (11) holds, then it represents the j-th minimum isolation region MA on the i-th feeder. ij In the event of a fault, the feeder satisfies the N-1 safety analysis; otherwise, it does not satisfy the N-1 analysis.
[0039] Compared with existing technologies, this invention offers the following advantages: It provides an N-1 security analysis method for distribution networks based on a minimum isolation area information matrix. This method first describes the switch and transformer information within the minimum isolation area of all feeders in the distribution network using the minimum isolation area information matrix. Then, it determines the total load to be transferred downstream of the fault using the real-time load information matrix of the minimum isolation area. Next, it describes the active power margin that switches in the transfer path can carry using the switch information matrix and switch carrying capacity information matrix. Finally, by comparing the minimum margin information matrix with the total load to be transferred, it analyzes the restoreable power supply situation downstream of the fault area. This method can quickly perform N-1 security analysis of the distribution network, identifying minimum isolation areas and weak links that do not meet N-1 requirements. It is convenient and fast, and can meet the needs of real-time online calculation and analysis in the field. Attached Figure Description
[0040] Figure 1 This is a flowchart illustrating the method implementation of an embodiment of the present invention.
[0041] Figure 2 This is a power distribution network diagram in an embodiment of the present invention. Detailed Implementation
[0042] The present invention will be further described below with reference to the accompanying drawings and embodiments.
[0043] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.
[0044] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.
[0045] like Figure 1 As shown, this embodiment provides a distribution network N-1 security analysis method based on the minimum isolation region information array, including the following steps:
[0046] (1) Establish a minimum isolation area information matrix to describe the switch and transformer information in the minimum isolation area of all feeders in the distribution network.
[0047] (2) Establish a real-time load information array for the minimum isolation area to determine the total load to be transferred downstream of the fault.
[0048] (3) Establish a load transfer path switch information matrix and a switch carrying capacity information matrix to describe the active power margin that the switches in the transfer path can carry.
[0049] (4) Establish a minimum margin information matrix and compare the minimum margin information matrix with the total load to be transferred to realize the analysis of the downstream power supply situation of the fault area.
[0050] Circuit breakers, sectionalizing switches, and branch switches are isolation devices in power distribution networks. When a fault occurs, the faulty area can be isolated by opening the isolation devices, separating it from the entire distribution feeder; the load in the downstream area of the fault can be transferred and power restored by closing the tie switch.
[0051] The smallest isolation zone is defined as the connected area in a power distribution feeder that is bounded by an isolation device and contains no other isolation devices. The smallest isolation zone is the smallest unit for fault isolation, and any fault in any equipment within it, such as feeders or transformers, will result in the same isolated area.
[0052] like Figure 2 The power distribution network shown includes Bus1 and Bus2 as 10kV busbars of the substation, Feeder1 to Feeder4 as four feeders, S1 to S4 as substation outgoing circuit breakers for the feeders, L1 to L3 as tie switches, B1 to B19 as sectionalizing switches, T1 to T61 as distribution transformers, and Fault1 as the fault point.
[0053] By definition, the minimum isolation zone for fault point Fault1 is the area enclosed by switches B1 and B2. When the fault occurs, the substation outgoing circuit breaker S1 trips, causing power loss to the entire Feeder 1 feeder. Section switch B1 reports an overcurrent alarm signal to the distribution automation master station system. The feeder automation (FA) function determines that the fault occurs downstream of switch B1, and the fault can be isolated by tripping switches B1 and B2. Power can be restored to the upstream area of the fault by closing circuit breaker S1, and power can be restored to the downstream area of the fault by closing tie switch L1. When all equipment within the minimum isolation zone, including distribution transformers T4, T5, and T6, experiences a fault, the isolation range is the same: tripping switches B1 and B2. Therefore, the minimum isolation zone B1B2 can be treated as a whole for N-1 safety analysis. When a fault occurs within the minimum isolation zone B1B2, switches B1 and B2 open, separating the minimum isolation zone from feeder1. Power is restored upstream of the fault zone via circuit breaker S1, and downstream of the fault zone via tie switch L1. Power is restored to all areas affected by the fault, meeting the requirements of distribution network N-1.
[0054] Table 1 shows the information on each minimum isolation zone and the distribution transformers contained in Feeder1:
[0055] Table 1 Minimum Isolation Zone Information Table
[0056] area Area 1 Area2 Area 3 Area 4 Area 5 Area 6 Area 7 switch S1,B1 B1, B2 B2~B5 B4 B3,L2 B5, B6 B6,L1 Distribution transformer T1~T3 T4~T6 T7~T9 T10~T12 T13~T15 T16 T17, T18
[0057] A Minimum Isolation Area Information Matrix (MIAM) is established to describe the switch and transformer information within the minimum isolation area of all feeders in the distribution network. Specifically:
[0058]
[0059] In the formula, each row represents all the minimum isolation regions on a feeder; MA ij This is the information for the j-th minimum isolation zone on the i-th feeder. If the minimum isolation zone does not exist, the value is -1; i = 1, 2, ..., n, where n is the number of feeders in the distribution network; j = 1, 2, ..., m, where m is the maximum number of minimum isolation zones contained in the feeder.
[0060]
[0061] In the formula, the first row represents the switch information contained in the minimum isolation zone, and the second row represents the distribution transformer information contained in the minimum isolation zone; ma ij,1k This represents the unique identifier of the k-th switch in the j-th minimum isolation region on the i-th feeder; if the switch does not exist, it is represented by -1; ma ij,2kThis represents the unique identifier of the k-th transformer in the j-th minimum isolation region on the i-th feeder. If the transformer does not exist, it is represented by -1; k = 1, 2, ..., p, where p is the minimum isolation region MA. ij The maximum number of switches and distribution transformers contained therein.
[0062] A Real-Time Load Information Array (RLIM) is established to describe the total active power of real-time loads within the minimum isolation zones of all feeders in the distribution network. Specifically:
[0063]
[0064]
[0065] In the formula, RL ij MA is the j-th minimum isolation region on the i-th feeder. ij The real-time total active power, which is determined by MA ij The real-time active power of the transformers contained within is determined, in kW; if the minimum isolation zone does not exist, the value is -1; P(ma ij,2k ) is a distribution transformer ma ij,2k Real-time active power.
[0066] When a fault occurs, power supply to the upstream area is restored through the reclosing of the substation outgoing circuit breaker. If there is no tie switch in the downstream area, it indicates that the fault occurred on a branch line, and power supply cannot be restored downstream, thus failing to meet N-1. If there is a tie switch in the downstream area, but it is under maintenance or faulty and cannot be used normally, power supply to the downstream area also cannot be restored, failing to meet N-1. If there is a tie switch in the downstream area and it is operating normally, power supply to the fault area is restored by closing the tie switch. The total load to be transferred is determined by the real-time total load power of the minimum isolation area downstream of the fault, specifically:
[0067]
[0068] In the formula, TLBT ij MA is the j-th minimum isolation region on the i-th feeder. ij The total downstream load awaiting transfer during a fault, in kW; RL iw For MA ij The real-time total active power of the downstream minimum isolation zone; w = a, a+1, ..., h, where h is the maximum active power per unit area (MA). ij The minimum number of downstream isolation zones, where a is MA ij The smallest isolation zone downstream is numbered.
[0069] Starting from the tie switch, and based on the distribution network topology, the search proceeds in reverse order along the power flow until the fault area and the substation outgoing circuit breaker are reached. The area traversed constitutes a load transfer path. A load transfer path switch information matrix (LTSM) is established to describe the switch information in all transfer paths downstream of the fault, specifically:
[0070]
[0071] In the formula, each row contains switching information for a load transfer path, LT dc Let be the unique identifier of the c-th switch in the d-th load transfer path, where d = 1, 2, ..., f, f is the number of paths for load transfer downstream of the fault, and c = 1, 2, ..., e, e is the maximum number of switches included in all load transfer paths. If LT dc If it does not exist, use -1 to represent it.
[0072] Due to the current carrying capacity limitations of equipment such as switches, the load will be affected by the rated power of switches in the power transfer path during the power transfer process; a Switch Capacity Information Matrix (SCIM) is established to describe the active power margin that switches in the power transfer path can carry, specifically:
[0073]
[0074] SC dc =S(LT) dc )-P(LT dc (8)
[0075] In the formula, each row represents the active power margin that the switches in a load transfer path can carry, S(LT). dc ) is the switch LT dc Rated active power, P(LT) dc ) is the switch LT dc Real-time active power; SC dc For switch LT dc The active power margin that can be carried is expressed in kW. If the switch is not present, it is represented by -1.
[0076] During load transfer, the load is limited by the minimum carrying capacity margin in the transfer path. A Minimum Margin Information Matrix (MMIM) is established to describe the active power margin that switches in each transfer path can carry, specifically:
[0077] MMIM = [MM1 MM2 … MM] d …MM f (9)
[0078] MM d =min(SC) d1 ,SCd2 ,…,SC dc ,…,SC de (10)
[0079] In the formula, MM d Let d be the minimum value in the d-th row of the switch load-bearing capacity information matrix SCIM, and min() is used to take the minimum value.
[0080] If the downstream loads affected by the fault can have their power restored through a joint power transfer path, then the N-1 analysis is also satisfied; specifically:
[0081]
[0082] If formula (11) holds, then it represents the j-th minimum isolation region MA on the i-th feeder. ij In the event of a fault, the feeder satisfies the N-1 safety analysis; otherwise, it does not satisfy the N-1 analysis.
[0083] In this embodiment, the active power of each transformer and switch in the power distribution network is as follows: Figure 2 As shown, the rated power limit of the substation outgoing circuit breakers S1 to S4 is 1600kW, the rated power limit of the sectionalizing switch B8 is 800kW, the rated power limit of the sectionalizing switch B13 is 500kW, and the rated power limit of the tie switches L1 to L4 and other sectionalizing switches is 1500kW.
[0084] According to this method, assuming a fault occurs in the minimum isolation area enclosed by switches B1 and B2, power supply to the upstream area can be restored by closing circuit breaker S1. The downstream area has two power transfer paths: one is through feeder 2 via the closing of tie switch L1, and the other is through feeder 3 via the closing of tie switch L2.
[0085] According to formulas (1) to (5), the load TLBT that needs to be transferred can be determined. ij The power is 1059kW. The load transfer path switch information matrix can be generated using formula (6) as follows:
[0086]
[0087] The switch bearing capacity information matrix can be generated from formulas (7) to (8) as follows:
[0088]
[0089] The minimum margin information matrix generated by formulas (9) to (10) is as follows:
[0090] MMIM = [310 334]
[0091] From formula (11), we can see that:
[0092] 1059 > 310 + 334
[0093] It does not satisfy formula (11), so the downstream area of the fault cannot achieve complete power transfer and restoration, which does not satisfy the N-1 analysis.
[0094] The N-1 analysis for other minimum isolation region faults is similar and will not be repeated here.
[0095] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.
Claims
1. A distribution network N-1 security analysis method based on a minimum isolation region information array, characterized in that, include: Establish a minimum isolation area information matrix to describe the switch and transformer information within the minimum isolation area of all feeders in the distribution network; Establish a real-time load information matrix for the minimum isolation zone to determine the total load to be transferred downstream of the fault; Establish a load transfer path switch information matrix and a switch carrying capacity information matrix to describe the active power margin that switches in the transfer path can carry. A minimum margin information matrix is established, and the minimum margin information matrix is compared with the total load to be transferred to achieve the analysis of the downstream power supply status of the fault area. The minimum isolation zone is defined as the connected area in a power distribution feeder that is bounded by an isolation device and contains no other isolation devices. The minimum isolation zone is the smallest unit for fault isolation, and the isolation area is the same for any device within it that fails. A Minimum Isolation Area Information Matrix (MIAM) is established to describe the switch and transformer information within the minimum isolation area of all feeders in the distribution network. Specifically: (1) In the formula, each row represents all the minimum isolation regions on a feeder; MA ij This is the information of the j-th minimum isolation zone on the i-th feeder. If the minimum isolation zone does not exist, the value is -1; i = 1, 2, ..., n, where n is the number of feeders in the distribution network; j = 1, 2, ..., m, where m is the maximum number of minimum isolation zones contained in the feeder. (2) In the formula, the first row represents the switch information contained in the minimum isolation zone, and the second row represents the distribution transformer information contained in the minimum isolation zone; ma ij,1k This represents the unique identifier of the k-th switch in the j-th minimum isolation region on the i-th feeder; if the switch does not exist, it is represented by -1. ma ij,2k This represents the unique identifier of the k-th transformer in the j-th minimum isolation region on the i-th feeder. If the transformer does not exist, it is represented by -1; k = 1, 2, ..., p, where p is the minimum isolation region MA. ij The maximum number of switches and distribution transformers contained therein; A Switch Capacity Information Matrix (SCIM) is established to describe the active power margin that switches in the power transfer path can carry. Specifically: (7) (8) In the formula, each row represents the active power margin that the switches in a load transfer path can carry, S(LT). dc ) is the switch LT dc Rated active power, P(LT) dc ) is the switch LT dc Real-time active power; SC dc For switch LT dc The active power margin that can be carried, in kW. If the switch is not present, it is represented by -1; LT dc Let f be the unique identifier of the c-th switch in the d-th load transfer path, where d = 1, 2, ..., f, f is the number of paths for load transfer downstream of the fault, and c = 1, 2, ..., e, e is the maximum number of switches included in all load transfer paths. The load transfer process is limited by the minimum carrying capacity margin in the transfer path; a minimum carrying capacity information matrix (MMIM) is established to describe the active power margin that switches in each transfer path can carry, specifically: (9) (10) In the formula, MM d Let be the minimum value in the d-th row of the switch bearing capacity information matrix SCIM, and min() is the minimum value. If the downstream loads affected by the fault can have their power restored through a joint power transfer path, then the N-1 analysis is also satisfied; specifically: (11) In the formula, TLBT ij MA is the j-th minimum isolation region on the i-th feeder. ij The total downstream load to be transferred during a fault, in kW; if formula (11) holds, then it represents the j-th minimum isolation zone MA on the i-th feeder. ij In the event of a fault, the feeder satisfies the N-1 safety analysis; otherwise, it does not satisfy the N-1 analysis.
2. The N-1 security analysis method for distribution networks based on the minimum isolation region information array according to claim 1, characterized in that, A Real-Time Load Information Array (RLIM) is established to describe the total active power of real-time loads within the minimum isolation zones of all feeders in the distribution network. Specifically: (3) (4) In the formula, RL ij MA is the j-th minimum isolation region on the i-th feeder. ij The real-time total active power of the load, which is determined by MA ij The real-time active power of the transformers contained within is determined, in kW; if the minimum isolation zone does not exist, the value is -1; P(ma ij,2k ) is a distribution transformer ma ij,2k Real-time active power; When a fault occurs, power supply to the upstream area is restored through the reclosing of the substation outgoing circuit breaker. If there is no tie switch in the downstream area, it indicates that the fault occurred on a branch line, and power supply cannot be restored downstream, thus failing to meet N-1. If there is a tie switch in the downstream area, but it is under maintenance or faulty and cannot be used normally, power supply to the downstream area also cannot be restored, failing to meet N-1. If there is a tie switch in the downstream area and it is operating normally, power supply to the fault area is restored by closing the tie switch. The total load to be transferred is determined by the real-time total active power of the minimum isolation area downstream of the fault, specifically: (5) In the formula, RL iw For MA ij The real-time total active power of the downstream minimum isolation zone; w = a, a+1, ..., h, where h is the maximum active power per unit area (MA). ij The minimum number of downstream isolation zones, where a is MA ij The smallest isolation zone downstream is numbered.
3. The N-1 security analysis method for distribution networks based on the minimum isolation region information array according to claim 1, characterized in that, Starting from the tie switch, and based on the distribution network topology, the search proceeds in reverse order along the power flow until the fault area and the substation outgoing circuit breaker are reached. The area traversed constitutes a load transfer path. A load transfer path switch information matrix (LTSM) is established to describe the switch information in all transfer paths downstream of the fault, specifically: (6) In the formula, each row contains switching information included in a load transfer path. If LT dc If it does not exist, use -1 to represent it.