Hierarchical power distribution network system, construction method and collaborative load transfer control method

Abstract

The application relates to the technical field of power distribution network architecture, and provides a layered power distribution network system, a building method and a collaborative load transfer control method.The layered power distribution network system comprises a main layer, a secondary main layer and a user layer.The main layer comprises three or four switch stations, and all the switch stations in the main layer are connected through cables to form a closed loop network structure.The total number of power supply paths of the closed loop network structure is equal to twice the number of the switch stations.The secondary main layer comprises a plurality of segments formed by power supply lines, each segment is interconnected through a looped network cabinet, and each segment is connected to different switch stations in the main layer to form a single loop network or a double loop network structure.The user layer comprises a power distribution room, the power distribution room is provided with double power supply access equipment, the double power supply access equipment comprises a first access point and a second access point, the first access point is connected to the looped network cabinet in the secondary main layer, and the second access point is connected to the switch station in the main layer.The application solves the problem that self-healing is difficult to implement under the conditions of tight interval resources in substations and limited line corridors.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power distribution network architecture, in particular to a hierarchical power distribution network system, a building method and a collaborative load transfer control method. BACKGROUND

[0002] In recent years, with the rapid increase of urban load density and the high penetration of distributed energy, the construction of power distribution network is facing two major contradictions:

[0003] First, the interval resources between substations are severely scarce. The traditional double-loop network and radial network architecture need to reserve independent intervals for each circuit. A single 110kV substation needs to be configured with 12 10kV outgoing line intervals to meet the double-loop network architecture, resulting in an interval utilization rate of more than 85%, which directly restricts the landing of the target network architecture.

[0004] Second, the line corridor redundancy and self-healing logic conflict. In order to alleviate the interval pressure, the existing technology tends to increase the line connection points in the limited corridor to form a complex multi-section ring network structure. However, this scheme will cause the self-healing strategy to fail, the excessive connection points will cause the protection setting value to be difficult to cooperate, the centralized master station cannot complete the multi-branch fault path search within 500ms, and the misjudgment rate is high. In addition, it also leads to the overdraft of corridor resources, and the single-circuit cable channel is forced to carry 3-4 cross connections, and the risk of fault spread is increased.

[0005] The root cause is that the problem is attempted to be solved by isomorphic redundancy (such as full double-loop network) or excessive connection, which further aggravates the consumption of interval and corridor resources, forming a vicious cycle of "reliability improvement-resource overload-control failure". SUMMARY

[0006] Therefore, the purpose of the present application is to overcome the problems of interval resource shortage of substations and difficulty in self-healing implementation under the limitation of line corridor in the prior art, and to provide a hierarchical power distribution network system, a building method and a collaborative load transfer control method. Through the design of hierarchical decoupling topological architecture and cross-level differentiated communication collaboration, without relying on complex control equipment, the interval and corridor resource bottleneck of the traditional power distribution network is directly broken through, and at the same time, the cross-level data interaction provides a basic framework support for self-healing collaboration, forming a power distribution network system with resource saving and high reliability.

[0007] In the first aspect, in order to solve the above technical problems, the present application provides a hierarchical power distribution network system, comprising,

[0008] The main layer includes three or four switch stations, and all switch stations included in the main layer are connected by cables to form a closed loop network structure; wherein the total number of power supply paths of the closed loop network structure is equal to twice the number of switch stations;

[0009] The secondary trunk layer includes a plurality of segments formed by power supply lines, each of the segments is interconnected by a ring network cabinet, and each of the segments is connected to a different main trunk layer switch station to form a single ring network or a double ring network structure.

[0010] The user layer includes a power distribution room, the power distribution room is configured with a dual power supply access device, the dual power supply access device includes a first access point and a second access point, the first access point is connected to the secondary trunk layer ring network cabinet, and the second access point is connected to the main trunk layer switch station.

[0011] The main trunk layer, the secondary trunk layer and the user layer are connected through a differentiated communication protocol to realize data interaction.

[0012] Preferably, the four switch stations are a first switch station, a second switch station, a third switch station and a fourth switch station, and the closed ring network structure is formed based on quadrilateral interconnection wiring of the four switch stations; the first switch station is connected to the second switch station through a first cable and connected to the fourth switch station through a second cable; the second switch station is connected to the third switch station through a third cable; and the third switch station is connected to the fourth switch station through a fourth cable.

[0013] Preferably, the cross-sectional area of the cable is greater than or equal to 400 mm2.

[0014] Preferably, the layered self-healing system includes an optical difference protection device and a backup protection device configured in the main trunk layer; when the optical difference protection device detects a fault, it sends a locking signal to the backup protection device, and the backup protection device performs load transfer after receiving the locking signal; a wireless communication module configured in the secondary trunk layer, the wireless communication module communicates with the master station based on LoRKG1WKG1N protocol or 4G communication protocol, uploads the load data and fault information of the ring network cabinet to the master station, and the master station generates an optimal transfer path based on topology analysis and issues an instruction to the target ring network cabinet; and a voltage monitoring module and a backup automatic switching device configured in the user layer; the voltage monitoring module monitors the power supply data on the user side in real time; when the voltage on the user side drops by more than a threshold value, the backup automatic switching device is triggered to switch to a backup power supply; the priority of the backup automatic switching device, the backup protection device and the secondary trunk layer master station self-healing control is I, II and III in turn.

[0015] Preferably, the master station generates an optimal transfer path based on topology analysis, including constructing an adjacency matrix with ring network cabinets as nodes and line impedance as weights; generating a candidate path set from the fault point to the backup power supply based on the Dijkstra algorithm; arranging the candidate path set in ascending order of impedance to obtain a candidate path set ; and selecting the optimal transfer path from the candidate path set obtaining a shortest impedance path; checking the shortest impedance path according to the following checking condition:

[0016] I rated ≥max(1.2I max , I fault );

[0017] if the shortest impedance path meets the checking condition, the shortest impedance path is the optimal transfer path; if not, starting suboptimal path checking; wherein, I rated is the line real-time carrying capacity of the shortest impedance path; I max is the historical maximum load; I fault is the instantaneous load before the fault.

[0018] Preferably, the master station generates the optimal transfer path based on topology analysis, and further comprises if the candidate path set is not determined, triggering cross-layer cooperative transfer.

[0019] Preferably, during the switching of the backup device, the operation instructions of the sub-main layer and the main layer to the voltage drop exceeding the threshold value are blocked, which comprises sending a blocking signal to the sub-main layer ring network cabinet and the main layer backup protection device 100us before the switching starts; the blocking signal lasts until the switching is completed and the voltage is restored to the rated value ± 5% for a set time; after the blocking signal is released, a state recovery instruction is sent to the sub-main layer ring network cabinet for the sub-main layer master station to update the topology data synchronously.

[0020] Preferably, the main layer, the sub-main layer and the user layer realize data interaction through a differentiated communication protocol, including that the switch station of the main layer is directly connected with the substation dispatching system based on a double-ring fiber channel, the channel switching delay of the double-ring fiber channel is ≤10ms; the sub-main layer ring network cabinet interacts with the master station based on a wireless communication gateway; the user layer interacts with the sub-main layer ring network cabinet based on an Internet of Things terminal.

[0021] The second aspect is to solve the above technical problems, and the application further provides a multi-layer cooperative load transfer control method, which is executed based on the layered power distribution network system, and the load transfer control method comprises,

[0022] When the main layer detects a substation total stop fault, the load transfer is performed based on the backup protection device in the closed ring network structure;

[0023] If the main layer transfer fails, the wireless communication module of the sub-main layer sends a cross-layer transfer request to the master station, the master station generates a cross-layer transfer path based on topology analysis, and controls the sub-main layer ring network cabinet to open and close according to the cross-layer transfer path;

[0024] If the secondary dry layer fails to supply, the backup power device of the user layer is triggered to switch to the standby power supply based on the voltage monitoring result; wherein, the pre-switching instruction is sent to the backup power device of the user layer, so that it enters the standby power supply hot standby state; the non-critical user load is cut off, and the critical user power supply capacity is preferentially guaranteed.

[0025] In a third aspect, to solve the above technical problems, the application further provides a layered power distribution network building method, characterized in that it comprises,

[0026] According to the city planning and load density distribution, the target area is divided into multiple power supply grids, and each power supply grid is further divided into several power supply units;

[0027] A main layer is planned in the power supply grid, the main layer includes three or four switch stations, and all switch stations included in the main layer are connected by cables to form a closed ring network structure;

[0028] A secondary dry layer is planned in the power supply unit, the secondary dry layer includes multiple segments divided by power supply lines, each segment is interconnected by a ring network cabinet, and each segment is connected to different main layer switch stations to form a single ring network or a double ring network structure;

[0029] A user layer is deployed on the user side, the user layer includes a power distribution room, the power distribution room is configured with a dual power supply access device, the dual power supply access device includes a first access point and a second access point, the first access point is connected to the secondary dry layer ring network cabinet, and the second access point is connected to the main layer switch station;

[0030] A layered communication system is configured, including an optical fiber communication terminal configured in the main layer switch station, directly connected with the substation dispatching system; a wireless communication gateway configured in the secondary dry layer ring network cabinet, interacting with the main station; and an Internet of Things terminal configured in the user layer power distribution room, communicating with the secondary dry layer ring network cabinet;

[0031] A layered self-healing system is configured, including an optical difference protection device and a backup power device installed in the main layer switch station; a wireless communication module integrated in the secondary dry layer ring network cabinet; and a backup power device and a voltage monitoring module configured in the user layer power distribution room.

[0032] The above technical solutions of the application have the following beneficial effects compared with the prior art:

[0033] The layered power distribution network system, building method and collaborative load transfer control method provided by the application break through the interval and corridor resource bottleneck of the traditional power distribution network directly without relying on complex control equipment, and at the same time, provide basic framework support for self-healing collaboration through cross-level data interaction, forming a power distribution network system with resource saving and high reliability.

[0034] Three or four switch stations are connected head to tail by cables to form a closed loop network (such as a double loop network or a multi-loop network), the total number of power supply paths is equal to twice the number of switch stations, so that a single interval can carry a multi-direction power supply task (such as one switch station supplying power to two loop networks in different directions), the interval resource reuse rate is improved by more than 40%, and the monopoly occupation of the interval by the traditional single loop network / radial structure is broken through.

[0035] The secondary trunk layer power supply line is divided into multiple segments, each segment is interconnected by a looped network cabinet and connected to different main trunk layer switch stations; for example, a single loop line is divided into three segments and connected to three switch stations, a redundant loop is formed by the looped network cabinet to reduce the outgoing interval demand of a single switch station.

[0036] When the secondary trunk layer is interconnected to form a single loop network or a double loop network through a looped network cabinet, the existing cable channel can be directly used to avoid repeated excavation for new tie lines, and the corridor utilization rate is improved.

[0037] The secondary trunk layer loop network structure is based on segmented access to the main trunk layer, reducing the complex multi-loop line cross-connection, and reducing the path search complexity of the self-healing strategy.

[0038] The user layer distribution room obtains double power supply through the first access point and the second access point, realizes cross-level redundant power supply, and when the secondary trunk layer fails, the user can directly maintain power supply through the main trunk layer power supply, and the user side power failure probability is reduced.

[0039] The main trunk layer, the secondary trunk layer, and the user layer realize data interaction through differentiated communication protocols, support cross-layer transmission and collaborative control of fault information, and shorten the fault positioning time to seconds. BRIEF DESCRIPTION OF DRAWINGS

[0040] In order to make the content of the present application more easily and clearly understood, the present application will be further described in detail below according to specific embodiments of the present application and in conjunction with the accompanying drawings, wherein,

[0041] Figure 1 The structure block diagram of the layered power distribution network system in the preferred embodiment of the present application is shown in the figure;

[0042] Figure 2 The layered self-healing system in the preferred embodiment of the present application is shown in the figure; Figure 1 The layered power distribution network system and the substation bus connection schematic diagram are shown in the figure;

[0043] Figure 3 The structure block diagram of the layered self-healing system in the preferred embodiment of the present application is shown in the figure;

[0044] Figure 4 The flowchart of the multi-level collaborative load transfer control method in the preferred embodiment of the present application is shown in the figure;

[0045] Figure 5The flow chart of the method for building the layered power distribution network in the preferred embodiment of the present application;

[0046] Figure 6 The topology map of Linfen central urban area before the reconstruction;

[0047] Figure 7 For Figure 6 The topology map after the reconstruction.

[0048] The description of the figures in the specification: 10-main layer, 20-secondary layer, 30-user layer. DETAILED DESCRIPTION

[0049] The present application will be further described below in conjunction with the figures and specific embodiments, so that those skilled in the art can better understand the present application and implement it, but the embodiments are not limiting to the present application.

[0050] Example 1:

[0051] Referring to Figure 1 and Figure 2 It is shown that the embodiment of the present application discloses a layered power distribution network system, which comprises a main layer 10, a secondary layer 20 and a user layer 30. The main layer comprises three or four switch stations, and all the switch stations in the main layer are connected by cables to form a closed ring network structure. The total number of power supply paths of the closed ring network structure is equal to twice the number of the switch stations. The secondary layer comprises a plurality of segments formed by power supply lines, each segment is interconnected by a ring network cabinet, and each segment is connected to different main layer switch stations to form a single ring network or a double ring network structure. The user layer comprises a power distribution room, which is provided with a dual power supply access device. The dual power supply access device comprises a first access point and a second access point. The first access point is connected to the secondary layer ring network cabinet, and the second access point is connected to the main layer switch station.

[0052] In specific application scenarios, the backbone layer includes three or four switch stations, preferably four: switch station KG1, switch station KG2, switch station KG3, and switch station KG4. The four switch stations KG1, KG2, KG3, and KG4 are interconnected in a crisscross pattern to form a closed loop network. For example, switch station KG1 is connected to switch station KG2 (KG1-KG2) via a first cable and to switch station KG4 (KG1-KG4) via a second cable; switch station KG2 is connected to switch station KG3 (KG2-KG3) via a third cable; and switch station KG3 is connected to switch station KG4 (KG3-KG4) via a fourth cable. Two independent cables are laid between each of the following KG1-KG2, KG2-KG3, KG3-KG4, and KG1-KG4 connections, resulting in a total of 4 × 2 = 8 paths. The closed-loop structure allows a single circuit bay to carry out power supply tasks in multiple directions (such as a switch station supplying power to two ring network directions at the same time), increasing the bay resource reuse rate by more than 40%, breaking through the exclusive occupation of bays by the traditional single-ring network / radial structure.

[0053] During network setup, the busbars of the four switching stations KG1, KG2, KG3, and KG4 are respectively connected to the busbars of the four substations. The four busbars can originate from two, three, or four substations. When there are four substations, the busbars of the four switching stations KG1, KG2, KG3, and KG4 are respectively connected to the four busbars of the four substations.

[0054] The main layer of multiple switching stations forms a closed loop network structure through cables. Only a few substation outgoing lines are needed to cover multiple switching stations, freeing up bay resources and alleviating bay resource shortages. In addition, when a substation fails, the load is quickly transferred through the main layer closed loop network structure, so that users do not lose power and achieve full power outage and full transfer.

[0055] The secondary trunk layer includes a plurality of segments formed by dividing the power supply lines, each of the segments is interconnected by a ring network cabinet, and each of the segments is connected to different main trunk layer switch stations to form a single ring network or a double ring network structure. For example, each power supply line is divided into two segments A and B, the first end of the segment A is connected to the switch station KG1, and the first end of the segment B is connected to the switch station KG2. If each power supply line is divided into three segments A, B and C, the first end of the segment A is connected to the switch station KG1, the first end of the segment B is connected to the switch station KG2, and the first end of the segment C is connected to the switch station KG1. The single ring network is connected to two different main trunk layer switch stations by the ring network cabinet for each segment to form a single closed loop structure, which ensures that power supply can be provided through the switch station on the other side when any segment fails. The double ring network is two independent closed loops, and the segment lines of each closed loop are still connected to two different main trunk layer switch stations, but the overall double ring network structure is supported by four main trunk layer switch stations. For example, ring 1: segments A, B and C are connected to the switch stations KG1 and KG2 (the connection method is the same as above); ring 2: segments D, E and F are connected to the switch stations KG3 and KG4, and the double rings are interconnected through a tie switch (or a ring network cabinet) to form a higher redundancy, and power supply can still be transferred under N-2 failure. Under the double ring network structure, single segment line failure can be transferred through the same ring or cross-ring path, and the risk of group load loss is reduced.

[0056] The power supply lines of the secondary trunk layer do not need to directly occupy the transformer substation bay, but are transferred through the main trunk layer, thereby further releasing the bay resources; in addition, through segment control, the failure influence range is reduced to the secondary trunk layer ring network, and the group load loss is reduced.

[0057] The following compares three segments connected to three different switch stations in the prior art and three segments connected to two different switch stations in the embodiment of the present application:

[0058] Three segments A, B and C in the prior art are connected to three different switch stations KG1, KG2 and KG3, when the switch station KG1 fails, the segment A is powered off, and the segments B and C are not affected, but 3 bays and 3 independent corridors need to be occupied.

[0059] In the embodiment of the present application, three segments are connected to two different switch stations, which satisfies the non-adjacent segment multiplexing the same station (or the bay segment multiplexing the same switch station), the segment A is connected to the switch station KG1, the segment B is connected to the switch station KG2, and the segment C is connected to the switch station KG1. When the switch station KG1 fails, the segment A and the segment C are interconnected by the ring network cabinet to be transferred to the switch station KG2, the three segments are all powered by the switch station KG2, and the segments A, B and C are not affected, and only two bays are needed.

[0060] Therefore, the layered power supply network based on the embodiment of the present application reduces the bay requirement while ensuring the power supply reliability.

[0061] The user layer configures a dual power access device, a first access point of the dual power access device connects a secondary trunk layer ring net cabinet as a main power supply, a second access point connects a main trunk layer switch station as a backup power supply, the dual power supplies are mutual backups, when the main power supply fails, the backup power supply is automatically put into operation, and the switching time is shorter than a user sensitive device tolerance threshold (such as millisecond level), and the system is especially suitable for hospitals, data centers and other scenes with extremely high requirements for power supply continuity.

[0062] In summary, the hierarchical power distribution network system described in the embodiment of the application releases interval resources by the main trunk layer composed of switch stations for global load transfer and full stop and full transfer; reduces network loss by the secondary trunk layer formed by connecting different main trunk layer switch stations by ring net cabinets through power supply lines for local load transfer; realizes uninterrupted power supply for users by the user layer with dual power supplies as mutual backups; forms triple redundancy of the main trunk layer (ring net), the secondary trunk layer (multiple transfer paths) and the user layer (dual power supply + load grading), and can still guarantee power supply for core load under N-2 system failure.

[0063] On the other hand, the main trunk layer, the secondary trunk layer and the user layer realize data interaction through differentiated communication protocols, specifically, the main trunk layer switch station is directly connected with a substation dispatching system based on a dual-ring fiber channel, the channel switching delay of the dual-ring fiber channel is ≤10 ms; the secondary trunk layer ring net cabinet interacts with the main station based on a wireless communication gateway, the working frequency band is 470-510 MHz, the transmission power is ≤14 dBm, and the transmission delay for interaction with the main station is ≤50 ms; the user layer interacts with the secondary trunk layer ring net cabinet based on an Internet of Things terminal.

[0064] In a specific application scenario, the main trunk layer switch station needs high reliability and low delay communication as a high-voltage node, and optical fiber direct connection is adopted to meet the differential protection demand; the dual-ring fiber channel refers to two independent optical fiber communication loops, which are based on physical path separation and logical hot standby, so that when any loop fails, the communication is automatically switched to the standby loop, ensuring zero-interruption data transmission; the fiber channel directly accesses the communication interface (such as an SDH optical terminal or a switch) of the dispatching system, without passing through intermediate forwarding nodes, reducing transmission hops and reducing delay. The ring net cabinet is deployed in a dispersed manner, wireless communication avoids the high cost of laying optical fibers, and the bandwidth supports second-level command transmission. Differentiated communication of each layer provides basic architecture support for self-healing cooperation through cross-level data interaction.

[0065] In summary, the hierarchical power distribution network system described in the embodiment of the application breaks through the interval and corridor resource bottleneck of the traditional power distribution network directly without relying on complex control equipment, and at the same time, provides basic architecture support for self-healing cooperation through cross-level data interaction, forming a power distribution network system with resource saving and high reliability of power supply.

[0066] Specifically, the cross-sectional area of the cable is greater than or equal to 400 mm2. It should be noted that the cross-sectional area of the cable is greater than or equal to 400 mm2, which is not a simple parameter selection, but a deep coupling of physical characteristics and layered power distribution network system requirements, to achieve comprehensive improvement of transmission efficiency, reliability, economy and system scalability. The specific application effects are as follows: the cable with a cross-sectional area greater than or equal to 400 mm2 can carry a current greater than or equal to 800 A (copper core, ambient temperature 30 DEG C) under rated operating conditions, and can simultaneously meet the dual power supply path power supply demand of a single loop line; for example, when the main layer switch station KG1 fails, the secondary trunk layer segment (such as A, C) is transferred by the ring network cabinet interconnection cable (cross-sectional area greater than or equal to 400 mm2) from KG2, avoiding secondary power failure due to cable overload, and the cable load rate is less than or equal to 70% under line N-1 failure, meeting the redundancy design requirements of GB 50217-2018. The low impedance characteristic (R less than or equal to 0.075 omega / km) of the large cross-sectional area cable can reduce the cross-layer power transmission loss between the main layer and the secondary trunk layer, supporting energy-efficient scheduling under the "layer decoupling" architecture.

[0067] As a further improvement of the embodiment of the application, the layered power distribution network system further comprises a layered self-healing system, as shown in Figure 3 The layered self-healing system comprises an optical differential protection device and a backup protection device configured in the main layer; wherein the optical differential protection device sends a locking signal to the backup protection device after detecting a fault, and the backup protection device performs load transfer after receiving the locking signal; a wireless communication module configured in the secondary trunk layer, the wireless communication module communicates with the master station based on LoRKG1WKG1N protocol or 4G communication protocol, uploads the load data and fault information of the ring network cabinet to the master station, and the master station generates an optimal transfer path based on topology analysis and issues an instruction to the target ring network cabinet; and a voltage monitoring module and a backup automatic switching device configured in the user layer; wherein the voltage monitoring module monitors the power supply data on the user side in real time; the backup automatic switching device is triggered to switch to the backup power supply when the voltage drop on the user side exceeds the threshold; wherein the priority of self-healing control of the backup automatic switching device, the backup protection device and the secondary trunk layer master station is I, II and III in turn.

[0068] In a specific application scenario, the user layer starts the backup automatic switching device based on the monitoring result of the voltage monitoring module, and the self-healing control priority is I. The voltage monitoring module detects voltage drop, and the backup automatic switching device switches to the backup power supply within 20 ms, ensuring uninterrupted power supply to users.

[0069] The backbone layer is locally fast self-healing, decoupled from the master station, and has a self-healing control priority of level II. The optical fiber current differential protection is used to compare the current amplitude and phase at both ends of the line in real time, detect faults, support directional blocking logic, distinguish between intra-zone faults (such as switch station KG1 short circuit) and extra-zone faults (such as faults in the upper-level substation), and send a blocking signal to the backup protection device through a double-ring optical fiber channel to prevent misoperation. After receiving the blocking signal from the optical differential protection device, the backup protection device starts the local fast backup, opens the fault section switch, closes the standby power supply switch, and transfers the load through the interconnection cable of the ring network cabinet. The optical differential protection blocks the backup protection device within 25 ms, and the backup protection device isolates the fault and transfers the power within 50 ms.

[0070] The secondary backbone layer is controlled by the master station for self-healing, and has a self-healing control priority of level III. The wireless communication module uploads the load data (current, voltage, power, etc.) of the ring network cabinet at a certain frequency and pushes the fault information (location, type, recording data, etc.) in real time when a fault occurs. The master station generates an optimal transfer path according to the load data and fault information reported by the wireless communication module and issues instructions to the target ring network cabinet. After receiving the fault information, the master station generates an optimal transfer path and issues instructions within 3 seconds to restore power supply to the non-fault section.

[0071] Compared with the centralized decision self-healing scheme in the traditional scheme and the hierarchical self-healing system in the embodiment of the present application:

[0072] The traditional centralized self-healing scheme uploads all data to the master station, which has a large bandwidth pressure. If the master station fails, it will cause the self-healing function of the entire network to be dependent on the single-thread processing of the master station, and the recovery success rate is less than 80%.

[0073] Based on the hierarchical self-healing system in the embodiment of the present application, the user layer with a self-healing control priority of level I is independently controlled and does not depend on the master station. It can still act independently when the communication is interrupted, avoiding the risk of "one paralysis of the entire paralysis" in centralized systems. The wireless communication module transmits data on demand, reducing the probability of network congestion. The hierarchical self-healing system realizes multi-level parallel processing through time decoupling (millisecond / second level division of labor) and spatial decoupling (independent control of each layer), achieving a user-side power outage time of 20 ms (backup switch-over device switching), a fault section recovery time of 3 seconds, and no load loss in the entire network.

[0074] Further, the master station generates an optimal transfer path based on topology analysis, including constructing an adjacency matrix with ring network cabinets as nodes and line impedance as weights; generating a candidate path set from the fault point to the backup power supply based on the Dijkstra algorithm; arranging the candidate path set in ascending order of impedance to obtain a candidate path set ; obtaining the shortest impedance path according to the candidate path set ; and verifying the shortest impedance path according to the following verification conditions:

[0075] I rated ≥max(1.2Imax , I fault );

[0076] If the shortest impedance path meets the check condition, the shortest impedance path is the optimal transfer path; if not, start suboptimal path checking; wherein, I rated is the real-time line carrying capacity of the shortest impedance path; I max is the historical maximum load; I fault is the instantaneous load before the fault.

[0077] In a specific application scenario, the optimal transfer path generation scheme includes:

[0078] Construct an adjacency matrix: abstract all ring main units (RMUs) in the secondary dry layer as graph nodes, numbered as RMU1, RMU2,..., RMUn, and calculate the line impedance weight Z based on cable parameters; if RMUi and RMUj are directly connected, then the adjacency matrix element A ij = Z ij ; otherwise A ij = infinity, to construct the adjacency matrix.

[0079] Generate a candidate path set from the fault point to the backup power supply based on the Dijkstra algorithm:

[0080] Input the fault point position RMU_k and the available backup power supply access point, initialize the shortest path from the fault point RMU_k to all nodes as infinity, set the RMU_k distance as 0, traverse all adjacent nodes, update the shortest path, and iterate until the shortest path of RMU_m is found to generate a candidate path set , arranged in ascending order of impedance. For example, P1: RMU_k → RMU_a → RMU_m (Z=0.8Ω); P2: RMU_k → RMU_b → RMU_c → RMU_m (Z=1.2Ω).

[0081] Path checking: traverse the candidate path set in ascending order of impedance, check whether the I rated of each line segment in the path meets the check condition, and the shortest path that first meets the condition is the optimal transfer path; if not, check the suboptimal paths (such as P2, P3) in turn, until the optimal transfer path is found. If the candidate path set is not determined, trigger cross-layer collaborative transfer.

[0082] The layered power distribution network system disclosed in the embodiment of the application generates an optimal transfer path based on topology analysis of the main station, and a dynamic checking mechanism considering real-time load flow, historical load and load before failure reduces the overload risk of the transfer path from 35% to below 2%, and the success rate of transfer is increased to 98%. The layered system checking of the shortest path to the suboptimal path realizes full-scene coverage, and the complex fault recovery time is greatly shortened.

[0083] Further, during the switching of the backup power supply device, the operation instructions of the secondary trunk layer and the main trunk layer to the loop are blocked, which includes sending a blocking signal to the secondary trunk layer ring network cabinet and the main trunk layer backup protection device 100 microseconds before the switching starts; the blocking signal lasts until the switching is completed and the voltage is restored to the rated value ± 5% for a set time, and then is released; after the blocking signal is released, a state recovery instruction is sent to the secondary trunk layer ring network cabinet for the secondary trunk layer main station to synchronously update the topology data.

[0084] In a specific application scenario, the backup power supply device sends a blocking signal 100 microseconds before switching, forcibly locks the operation authority of the secondary trunk layer ring network cabinet and the main trunk layer backup protection device, completely avoids misoperation caused by cross-level instruction competition during switching (such as ring network cabinet misoperation and repeated transfer of backup protection), the blocking signal lasts until the voltage is restored to the rated value ± 5% and is stable for ≥500 ms, ensures that the power transient process after switching is completely calm, and prevents secondary faults (such as secondary off-network of sensitive equipment) caused by voltage fluctuations; after the blocking is released, the backup power supply device sends a state recovery instruction to the secondary trunk layer ring network cabinet, triggers the main station to update the topology data in real time, eliminates the global information lag caused by local operation, and ensures that the subsequent self-healing strategy is strictly consistent with the current network state. Through the strong timing control of “blocking first-recovery later”, the dual protection of fast switching of the user layer and stable system of cross-level is realized, supporting millisecond-level fault isolation and second-level global data synchronization.

[0085] Embodiment two:

[0086] Referring to Figure 4 The embodiment of the application discloses a multi-level cooperative load transfer control method based on the layered power distribution network system, which includes,

[0087] When the main trunk layer detects a substation total stop fault, load transfer is performed based on the backup protection device in the closed ring network structure;

[0088] If the main trunk layer fails to transfer, the wireless communication module of the secondary trunk layer sends a cross-layer transfer request to the main station, the main station generates a cross-layer transfer path based on topology analysis, and controls the secondary trunk layer ring network cabinet to open and close according to the cross-layer transfer path;

[0089] If the secondary dry layer fails to transfer, the backup power device of the user layer is triggered to switch to the standby power supply based on the voltage monitoring result; wherein, a pre-switching instruction is sent to the backup power device of the user layer, so that it enters the standby power supply hot standby state; the non-critical user load is cut off, and the critical user power supply capacity is preferentially guaranteed.

[0090] In a specific application scenario, the multi-level collaborative load transfer control method realizes multi-level collaborative load transfer based on the strategy of main layer priority response, secondary dry layer global optimization and user layer ultimate disaster recovery in the case of substation total failure. Specifically, in the case of substation total failure, millisecond-level local transfer is realized by closing the backup protection device in the ring network structure (action time ≤ 50 ms), avoiding dependence on upper-layer communication; if the main dry layer fails to transfer, the master station generates a cross-layer transfer path based on real-time topology, controls the ring network cabinet to open and close through wireless communication, and restores power supply in the non-fault area in seconds; when the secondary dry layer fails, the user layer backup power device switches to the standby power supply based on voltage monitoring, preferentially guarantees the critical users (such as hospitals and data centers), and the non-critical load cutting rate is ≤ 20%, realizing reasonable allocation of power supply capacity.

[0091] Embodiment three:

[0092] Referring to Figure 5 The embodiment of the application discloses a layered power distribution network building method, which comprises,

[0093] According to the city planning and the load density distribution, the target area is divided into a plurality of power supply grids, and each power supply grid is further divided into a plurality of power supply units;

[0094] The main dry layer is planned in the power supply grid, and the main dry layer comprises a plurality of switch stations connected by cables to form a closed ring network structure;

[0095] The secondary dry layer is planned in the power supply unit, and the secondary dry layer comprises a plurality of segments formed by power supply lines, each segment is interconnected by a ring network cabinet, and each segment is connected to different main dry layer switch stations to form a single ring network or a double ring network structure;

[0096] The user layer is deployed on the user side, and the user layer comprises a power distribution room, the power distribution room is provided with a dual power supply access device, the dual power supply access device comprises a first access point and a second access point, the first access point is connected to the secondary dry layer ring network cabinet, and the second access point is connected to the main dry layer switch station;

[0097] A layered communication system is configured, including an optical fiber communication terminal configured in the main dry layer switch station, which is directly connected with the substation dispatching system; a wireless communication gateway is configured in the secondary dry layer ring network cabinet, which interacts with the master station; an Internet of Things terminal is configured in the user layer power distribution room, which communicates with the secondary dry layer ring network cabinet;

[0098] The system is configured with a hierarchical self-healing system, including the installation of optical differential protection devices and backup protection devices in the main trunk layer switch stations; the integration of wireless communication modules in the secondary trunk layer ring network cabinets; and the configuration of backup automatic transfer devices and voltage monitoring modules in the user layer power distribution rooms.

[0099] The hierarchical power distribution network construction method described in this embodiment of the invention has the same technical effects as that in Embodiment 1, and will not be repeated here.

[0100] Based on the solutions in Embodiment 1 and Embodiment 3, the following description will be based on a specific application scenario:

[0101] Four switching stations—Yuelongtai, Wuyi West, Central City, and Caihong—were selected in the central urban area of ​​Linfen to construct a grid-like wiring system. The project area is bounded by Gulou West Street to the north, Binhe Road to the west, Changxing Middle Street to the east, and Xizhao Road to the south, forming an urban grid. The planned area within this region is 0.749 km². According to the municipal planning, the grid is positioned as a multi-functional urban complex, primarily residential with some commercial components. A comparison of the 10kV power grid before and after the upgrade is provided. Figure 6 and Figure 7 As shown,

[0102] The total investment in the project was 5.73 million yuan, including 3.7km of cable, 16 sets of optical differential protection, and 4 sets of backup protection. Through the simplification and optimization of the existing lines, a grid-shaped main trunk line connection was formed, consisting of "Yuelongtai Substation - Wuyi West Substation - Caihong Substation - Central City Substation", and 6 sets of secondary trunk line standard single-ring network connections. Seven bays of the substation were freed up for the construction of other target network structures, enabling the full shutdown and switching of loads connected to the four substations, as well as the hierarchical and unitized management of regional loads.

[0103] Analysis of the advantages and disadvantages of the double-ring network project:

[0104] 1. The project is relatively easy to implement. Utilizing existing cable channels, ring main units are installed near the network switching station to achieve grid layering and optimize the grid structure.

[0105] 2. More efficient fault restoration. Compared with the traditional dual-ring network centralized distribution automation self-healing method, the "well"-shaped main line can achieve protection self-healing within "4 seconds" through optical differential protection and backup protection.

[0106] 3. Low line operation and maintenance difficulty. Standard optical differential and backup protection are used, requiring no additional special equipment and minimal professional skills from maintenance personnel. Furthermore, the substation has relatively good operating conditions, allowing for comprehensive consideration of weather conditions such as flooding, high temperatures, and extreme cold during the upgrade process to ensure stable operation of communication and protection equipment.

[0107] 4. Engineering investment is more economical. A set of "well" connection, only need to configure 16 sets of optical difference protection, 4 sets of backup protection, and can solve the problem of "blind adjustment" of the substation without remote device in the community. While the double ring network connection, to achieve the same self-healing level, need to use distributed self-healing logic, configure distributed optical difference protection, etc., the investment cost is higher, suitable for high load density area.

[0108] Those skilled in the art will appreciate that embodiments of the application can be supplied as a method, a system, or a computer program product. Thus, the application can take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the application can take the form of a computer program product on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROMs, optical storage devices, etc.) embodying computer readable program code.

[0109] The application is described with reference to the flowcharts and / or block diagrams of the methods, apparatus (systems) and computer program products according to embodiments of the application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, as well as combinations of flows and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing apparatus to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing apparatus produce a device that implements the functions specified in the flowcharts and / or block diagrams. Figure 1 One or more flows and / or blocks Figure 1 An apparatus that performs the functions specified in one or more flows and / or blocks.

[0110] These computer program instructions can also be stored in a computer-readable memory that can direct the computer or other programmable data processing apparatus to work in a specific manner, so that the instructions stored in the computer-readable memory produce a manufactured product including instruction apparatus, which implements the functions specified in the flowcharts and / or block diagrams. Figure 1 One or more flows and / or blocks Figure 1 An apparatus that performs the functions specified in one or more flows and / or blocks.

[0111] These computer program instructions can also be loaded into a computer or other programmable data processing apparatus, so that a series of operation steps are performed on the computer or other programmable data processing apparatus to produce a computer-implemented process, so that the instructions executed on the computer or other programmable data processing apparatus provide a process for implementing the functions specified in the flowcharts and / or block diagrams. Figure 1 One or more flows and / or blocks Figure 1 An apparatus that performs the functions specified in one or more flows and / or blocks.

[0112] Obviously, the above embodiments are merely example for clearly illustrating, and are not limitation to the embodiments. For ordinary skilled in the art, other different forms of changes or variations can be made on the basis of the above description. Here, all the embodiments need not and can not be exhausted. The obvious changes or variations derived therefrom are still within the scope of the present invention.

Claims

1. A multi-tiered coordinated load transfer control method, characterized by: Based on the layered power distribution network system execution, the layered power distribution network system comprises: The main layer includes three or four switch stations, all switch stations included in the main layer are connected by cables to form a closed loop network structure; wherein the total number of power supply paths of the closed loop network structure is equal to twice the number of switch stations; The secondary trunk layer includes a plurality of segments formed by power supply lines, each segment is interconnected by a ring network cabinet, and each segment is connected to a different main layer switch station to form a single ring network or a double ring network structure; The user layer includes a power distribution room, the power distribution room is provided with a dual power supply access device, the dual power supply access device includes a first access point and a second access point, the first access point is connected to the secondary trunk layer ring network cabinet, and the second access point is connected to the main layer switch station; Wherein, the main layer, the secondary trunk layer and the user layer realize data interaction through differentiated communication protocol; The load transfer control method comprises, When the main layer detects a substation full stop fault, the load transfer is performed based on the backup protection device in the closed loop network structure; If the main layer transfer fails, the wireless communication module of the secondary trunk layer sends a cross-layer transfer request to the master station, the master station generates a cross-layer transfer path based on topology analysis, and controls the secondary trunk layer ring network cabinet to open and close according to the cross-layer transfer path; If the secondary trunk layer transfer fails, the backup protection device of the user layer switches to the standby power supply based on the voltage monitoring result; wherein, the pre-switching instruction is sent to the backup protection device of the user layer, so that it enters the standby power supply standby state; the non-critical user load is cut off, and the critical user power supply capacity is preferentially guaranteed.

2. The multi-tiered coordinated load shed control method of claim 1, wherein: The four switch stations are respectively a first switch station, a second switch station, a third switch station and a fourth switch station, and the four switch stations form the closed loop network structure based on quadrilateral interconnection wiring; Wherein, the first switch station is connected to the second switch station through a first cable and to the fourth switch station through a second cable; The second switch station is connected to the third switch station through a third cable; The third switch station is connected to the fourth switch station through a fourth cable.

3. The multi-tiered coordinated load shed control method of claim 2, wherein: The cross-sectional area of the cable is greater than or equal to 400 mm2.

4. The multi-tiered coordinated load shed control method of any of claims 1-3, wherein: It also includes a layered self-healing system, which comprises, The optical differential protection device and the backup protection device are configured in the main layer; wherein, after the optical differential protection device detects a fault, it sends a locking signal to the backup protection device, and the backup protection device performs load transfer after receiving the locking signal; The wireless communication module is configured in the secondary trunk layer, the wireless communication module communicates with the master station based on LoRKG1WKG1N protocol or 4G communication protocol, uploads the load data and fault information of the ring network cabinet to the master station, and the master station generates the optimal transfer path based on topology analysis and issues instructions to the target ring network cabinet; The voltage monitoring module and the backup protection device are configured in the user layer; wherein, the voltage monitoring module monitors the power supply data of the user side in real time; when the voltage drop of the user side exceeds the threshold, the backup protection device is triggered to switch to the standby power supply; The priority of the backup power injection device, the backup injection protection device and the secondary main station self-healing control is I, II and III in sequence.

5. The multi-tiered coordinated load shed control method of claim 4, wherein: The main station generates an optimal transfer path based on topology analysis, comprising, an adjacent matrix is constructed with ring network cabinets as nodes and line impedance as weights; a candidate path set from a fault point to a backup power source is generated based on Dijkstra algorithm; arranging the candidate path set in ascending order of impedance to obtain a candidate path set ; According to the candidate path set Obtaining the shortest impedance path; the shortest impedance path is verified according to the following verification condition: I rated ≥max(1.2I max ,I fault ); if the shortest impedance path meets the verification condition, the shortest impedance path is the optimal transfer path; otherwise, a suboptimal path verification is started; where I rated is the real-time current carrying capacity of the line for the shortest impedance path; I max is the historical maximum load; I fault is the instantaneous load before the fault.

6. The multi-tiered coordinated load shed control method of claim 5, wherein: The master station generates an optimal transfer path based on topology analysis, and further comprises triggering cross-layer cooperative transfer if the optimal transfer path is not determined The master station generates an optimal transfer path based on topology analysis, and further comprises triggering cross-layer cooperative transfer if the optimal transfer path is not determined 7. The multi-tiered coordinated load shed control method of claim 4, wherein: during switching of the backup power injection device, operation instructions of the secondary main station and the primary main station to a voltage drop exceeding a threshold value loop are blocked, which comprises, a blocking signal is sent to the secondary main station ring network cabinet and the primary backup injection protection device 100 microseconds before switching starts; the blocking signal lasts until switching is completed and the voltage is restored to the rated value ± 5% for a set time, and then is released; after the blocking signal is released, a state recovery instruction is sent to the secondary main station ring network cabinet for the secondary main station to update topology data synchronously.

8. The multi-tiered coordinated load shed control method of claim 1, wherein: data interaction is realized among the primary main station, the secondary main station and the user layer through a differentiated communication protocol, comprising, the primary main station switch station is directly connected with the substation dispatching system based on a dual-ring fiber channel, and the channel switching delay of the dual-ring fiber channel is less than or equal to 10 ms; the secondary main station ring network cabinet interacts with the main station based on a wireless communication gateway; the user layer interacts with the secondary main station ring network cabinet based on an Internet of Things terminal.

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