AC / DC power distribution system networking method suitable for different typical scenes

Abstract

The invention relates to an AC / DC power distribution system networking method suitable for different typical scenes, and the method comprises the following steps: S1, constructing a networking mode based on a grid structure of a DC power distribution network; s2, constructing a networking mode based on the wiring mode of the DC power distribution network; s3, constructing a networking mode based on the grounding mode of the DC power distribution network; s4, constructing a networking mode based on an alternating current and direct current interconnection mode and a system primary and secondary equipment configuration principle; and S5, networking the typical application scenes of the AC / DC power distribution system suitable for the different typical scenes based on the networking modes of the typical application scenes of the AC / DC power distribution system suitable for the different typical scenes constructed in the steps S1 to S4. According to the invention, the networking mode suitable for typical application scenes of the AC / DC power distribution system in different typical scenes is constructed, different power grid structures and operation modes are adapted, and safe power supply is ensured.

Description

Technical Field

[0001] The present invention belongs to the technical field of flexible interconnection, direct current power distribution, and AC / DC mixed supply, and relates to a networking method for an AC / DC power distribution system, and in particular to a networking method for an AC / DC power distribution system suitable for different typical scenarios. Background Art

[0002] The power grid is a key link in supporting carbon emission reduction in the energy system. The power grid will play a more important role in energy supply, consumption, transmission and conversion to meet various needs. The development of the distribution network is characterized by AC / DC interconnection, large-scale access of a high proportion of distributed new energy and power electronic equipment, and faces the dual challenges of ensuring continuous and stable supply and accelerating clean and low-carbon transformation. The access of distributed new energy power sources has the main impact on the operation of the power grid, which is excessive line voltage and excessive short-circuit current. The clustering effect of electric vehicle charging will have a greater impact on the local distribution network, and the development of large-scale electric vehicles will bring challenges to the power supply service of the distribution network. User-side energy storage brings safety risks to the power grid in terms of fire protection and maintenance, and the large-scale disorderly operation of user-side energy storage will affect the reliable operation of the power grid.

[0003] After searching, no public documents of the prior art that are identical or similar to the present invention were found. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and propose a networking method for an AC / DC power distribution system suitable for different typical scenarios. By constructing an AC / DC power distribution system networking mode suitable for different typical scenarios, it adapts to different power grid structures and operation modes, ensures the safe supply of electricity, and meets the requirements for the construction of new power systems.

[0005] The present invention solves the practical problem by adopting the following technical solutions:

[0006] A method for networking an AC / DC power distribution system suitable for different typical scenarios comprises the following steps:

[0007] S1. Based on the grid structure of DC distribution network, build AC / DC distribution system networking modes suitable for different typical scenarios;

[0008] S2. Based on the connection mode of DC distribution network, build AC / DC distribution system networking mode suitable for different typical scenarios;

[0009] S3. Based on the grounding method of the DC distribution network, build an AC / DC distribution system networking mode suitable for different typical scenarios;

[0010] S4. Based on the AC / DC interconnection mode and the configuration principles of the primary and secondary equipment of the system, build AC / DC distribution system networking modes suitable for different typical scenarios;

[0011] S5. Based on the AC / DC power distribution system networking modes adapted to different typical scenarios constructed in steps S1 to S4, AC / DC power distribution system networking adapted to different typical scenarios is performed.

[0012] Moreover, the grid structure of the DC distribution network in step S1 includes: a typical grid structure of a medium-voltage AC / DC hybrid distribution network including a flexible ring network control device, a medium-voltage DC distribution network grid structure, and a low-voltage DC busbar structure;

[0013] The typical grid structure of the medium voltage AC / DC hybrid distribution network containing the flexible ring network control device includes: a grid structure containing a two-terminal flexible ring network control device, and a grid structure containing a three-terminal flexible ring network control device;

[0014] The medium voltage DC distribution network grid structure includes: a single-end radial structure, a single-end ring network structure, a multi-end radial structure, and a multi-end ring structure;

[0015] The low voltage DC busbar structure includes: a single busbar structure, a double busbar structure, a layered busbar structure, and a redundant busbar structure;

[0016] Furthermore, the connection mode of the DC power distribution network in step S2 includes: a connection mode of a converter of a DC power distribution system;

[0017] Among them, the DC distribution system converter wiring forms include: single-pole structure and double-pole structure;

[0018] The monopole structure includes: a symmetrical monopole structure and an asymmetrical monopole structure;

[0019] The asymmetric monopole structure is divided into a monopole ground loop mode and a monopole metal loop mode;

[0020] The bipolar structure comprises: a positive busbar, a negative busbar and a neutral line;

[0021] Moreover, the grounding method of the DC distribution network in step S3 includes: a medium voltage DC distribution network grounding method and a low voltage DC distribution network grounding method;

[0022] Among them, the grounding methods of the medium voltage DC distribution network include: the grounding method of the flexible DC transmission system and the typical grounding method of the medium voltage DC distribution network; the grounding methods of the low voltage DC distribution network include: low voltage true bipolar connection and low voltage pseudo bipolar connection;

[0023] Moreover, the AC / DC interconnection mode and the primary and secondary equipment configuration principles of the system in step S4 include: typical technical principles of AC / DC interconnection mode, typical interconnection mode of AC / DC power distribution system, primary equipment configuration principles of AC / DC system, and secondary configuration principles of protection and automation, metering and communication systems;

[0024] Moreover, the specific steps of step S5 include:

[0025] (1) Initialize the networking failure flag signID = 0. Start traversal with node 1 as the root node, add the nodes visited in the traversal to the set Result = {1, 2, 3, 4}, and add the unvisited nodes in the line corridor to the set NotVisitNodes = {5, 8, 10, 11, 13};

[0026] (2) Take the first node in the unvisited node set, node 5, and search for the node set connected to node 5 by a DC corridor, namely AdjacentNodes = {3, 6, 7, 9, 10}. Determine the node set that can enable node 5 to access the established network after connecting to it, namely PossibleConnectingNodes = {3}. If there are multiple candidate access nodes, randomly select one as the connection point for the new node to access the existing network. In this example, the connection point of node 5 is node 3. Traverse the newly formed network and update the visited node set Result = {1, 2, 3, 4, 5} and the unvisited node set NotVisitNodes = {8, 10, 11, 12, 13}.

[0027] (3) Continue to take the first node in the set of unvisited nodes, node 8. If all the nodes connected to it are not in the established network, then put it at the last position of NotVisitNodes, NotVisitNodes = {10, 11, 12, 13, 8}, and the suspension count GZFlag of node 8 is increased by 1. After the remaining nodes are connected to the network, search for the access point of the node again.

[0028] (4) Continue to take the first node in NotVisitNodes to perform networking operations until the set of unvisited nodes is empty and the DC networking is completed. The network it forms is as follows: Figure 4 shown.

[0029] (5) If a node forms a ring network with existing nodes after access, then other nodes are selected from the nodes it is connected to. If all the nodes it is connected to cannot be networked, it is placed at the end of NotVisitNodes and its GZFlag is increased by 1. If a node still fails to access the existing network after being placed for 3 times, the networking fails and the networking failure flag signID is set to 1. In the particle swarm optimization calculation process, if a particle fails to network, the fitness value of the particle is set to inf, and the particle will not be selected as the optimal particle.

[0030] (6) The networking method is completed and the connection information of the formed network is generated.

[0031] Moreover, the typical application scenarios of the AC / DC power distribution system adapted to different typical scenarios in step S5 include: DC power distribution in DC load concentration areas, DC power distribution in industrial parks, DC transformation of urban load centers, DC power distribution for renewable energy generation, low-voltage flexible interconnection of AC / DC power distribution systems, county-scale photovoltaic access, and wind, solar, and storage microgrids;

[0032] The DC power distribution in the DC load concentration area includes: DC power distribution in data centers, DC power distribution in electric vehicle charging and swapping facilities, and DC power distribution in residential buildings.

[0033] Advantages and beneficial effects of the present invention:

[0034] The present invention proposes a networking method for AC / DC power distribution systems that are suitable for different typical scenarios. According to the grid structure, wiring method, and grounding method of multi-voltage level DC power distribution systems, the different characteristics and applicability are clarified; according to the existing AC / DC related standards and demonstration projects, the AC / DC interconnection method and the configuration principles of primary equipment such as DC power distribution system connection transformers, converters, DC transformers, DC circuit breakers, and DC lines, as well as the configuration principles of secondary equipment such as communication systems and protection systems, and the primary and secondary configuration principles of microgrids are refined; combined with the results of the division of typical application scenarios, system configuration schemes such as voltage level, grid structure, wiring method, and grounding method of DC power distribution systems under different application scenarios are proposed, and finally a networking scheme suitable for typical application scenarios of AC / DC power distribution systems such as DC load concentration areas (including data centers, electric vehicle charging and swapping facilities, and residential buildings), industrial parks, DC transformation of urban load centers, DC distribution that integrates renewable energy power generation, and wind, solar, and storage microgrids are formed. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A diagram of the data center power supply structure of the present invention;

[0036] Figure 2 This is a DC power distribution structure diagram of the electric vehicle charging and swapping facility of the present invention;

[0037] Figure 3 This is a structural diagram of a low-voltage flexible Internet of AC and DC power distribution systems of the present invention;

[0038] Figure 4 It is a schematic diagram of the DC power distribution network architecture of a certain area in a specific implementation manner of the present invention. DETAILED DESCRIPTION

[0039] The embodiments of the present invention are further described in detail below with reference to the accompanying drawings:

[0040] A networking method for an AC / DC power distribution system suitable for different typical scenarios, including: a grid structure of a DC distribution network, a wiring method of a DC distribution network, a grounding method of a DC distribution network, an AC / DC interconnection method and configuration principles of primary and secondary equipment of the system, and a networking method for typical scenarios of an AC / DC power distribution system (microgrid).

[0041] A method for networking an AC / DC power distribution system suitable for different typical scenarios comprises the following steps:

[0042] S1. Based on the grid structure of DC distribution network, build AC / DC distribution system networking modes suitable for different typical scenarios;

[0043] In this embodiment, the grid structure of the DC distribution network in step S1 includes: a typical grid structure of a medium-voltage AC / DC hybrid distribution network including a flexible ring network control device, a medium-voltage DC distribution network grid structure, and a low-voltage DC bus structure;

[0044] Among them, the typical grid structure of the medium-voltage AC / DC hybrid distribution network containing the flexible ring network control device includes: a grid structure containing a two-terminal flexible ring network control device, and a grid structure containing a three-terminal flexible ring network control device; the grid structure of the medium-voltage DC distribution network includes: a single-end radial structure, a single-end ring network structure, a multi-end radial structure, and a multi-end ring structure; the low-voltage DC busbar structure includes: a single busbar structure, a double busbar structure, a layered busbar structure, and a redundant busbar structure;

[0045] S2. Based on the connection mode of DC distribution network, build AC / DC distribution system networking mode suitable for different typical scenarios;

[0046] The connection mode of the DC power distribution network in step S2 includes: a connection mode of a DC power distribution system converter; wherein the connection mode of the DC power distribution system converter includes: a monopole structure and a bipole structure;

[0047] The monopole structure includes: a symmetrical monopole structure (also called a "pseudo-bipole" structure) and an asymmetrical monopole structure;

[0048] The asymmetric monopole structure can be further divided into a monopole polar loop mode and a monopole metal loop mode.

[0049] The bipolar structure includes a positive busbar, a negative busbar and a neutral line. Compared with a unipolar structure, it contains two voltage levels and can more effectively improve the utilization rate of a DC power supply system.

[0050] S3. Based on the grounding method of the DC distribution network, build an AC / DC distribution system networking mode suitable for different typical scenarios;

[0051] The grounding method of the DC distribution network in step S3 includes: a medium voltage DC distribution network grounding method and a low voltage DC distribution network grounding method;

[0052] Among them, the grounding methods of the medium voltage DC distribution network include: the grounding method of the flexible DC transmission system and the typical grounding method of the medium voltage DC distribution network; the grounding methods of the low voltage DC distribution network include: low voltage true bipolar connection and low voltage pseudo bipolar connection;

[0053] The grounding methods of the flexible direct current transmission system specifically include: the typical grounding method of VSC-HVDC (voltage source converter direct current transmission with pseudo bipolar connection), the typical grounding method of MMC-HVDC (modular multilevel converter direct current transmission with pseudo bipolar connection), and the typical grounding method of the true bipolar flexible direct current transmission system; the typical grounding methods of the medium voltage direct current distribution network specifically include: pseudo bipolar connection formed by MMC, pseudo bipolar connection formed by two-level converters, and medium voltage true bipolar connection.

[0054] S4. Based on the AC / DC interconnection mode and the configuration principles of the primary and secondary equipment of the system, build AC / DC distribution system networking modes suitable for different typical scenarios;

[0055] The AC / DC interconnection mode and the primary and secondary equipment configuration principles of the system in step S4 include: typical technical principles of AC / DC interconnection mode, typical interconnection mode of AC / DC power distribution system, primary equipment configuration principles of AC / DC system, and secondary configuration principles of protection and automation, metering and communication systems;

[0056] The typical technical principles of the AC / DC interconnection method include:

[0057] ① The interconnection between the DC distribution network and the AC distribution network should ensure the safe, reliable and efficient operation of the AC distribution network and the DC distribution network;

[0058] ② When the DC distribution network and the AC distribution network are interconnected, they should be able to isolate faults independently to reduce the impact of interconnection;

[0059] ③ The interconnection between DC distribution network and AC distribution network should follow the principle of voltage matching and mutual adaptation of transmission capacity;

[0060] ④ The determination of AC / DC interconnection voltage needs to take into account the existing AC voltage and DC voltage sequence, distributed power sources and convenient access of users;

[0061] ⑤ The determination of technical requirements for AC / DC interconnection devices needs to comprehensively consider factors such as technological development and equipment manufacturing level;

[0062] ⑥ The relay protection of the interconnection between the DC distribution network and the AC distribution network should meet the requirements of reliability, selectivity, sensitivity and speed;

[0063] ⑦ The grounding method of the DC distribution system should be coordinated with the grounding method of the AC system, the type of AC / DC converter, the converter topology, and the reliability requirements and insulation design of the DC system, and should be considered comprehensively;

[0064] ⑧The AC / DC interconnection device generally includes typical components such as connection (commutation) transformers, converters, DC reactors, and DC circuit breakers; the AC / DC interconnection device can be composed of multiple components that independently perform a single function, or it can be a single component that integrates multiple functions.

[0065] The typical interconnection modes of the AC / DC power distribution system include:

[0066] ① Direct interconnection via unidirectional power transmission converter;

[0067] ②Isolated and interconnected with the unidirectional power transmission converter via a 1:1 connection (commutation) transformer;

[0068] ③Isolated and interconnected with the unidirectional power transmission converter via the step-up / step-down connection (commutation) transformer;

[0069] ④ Direct interconnection via bidirectional power transmission converter;

[0070] ⑤Isolated and interconnected with the bidirectional power transmission converter via a 1:1 connection (commutation) transformer;

[0071] ⑥Isolated and interconnected with the bidirectional power transmission converter via a step-up / step-down connection (commutation) transformer.

[0072] ⑦ The typical topological structures of AC / DC interconnection mainly include AC-DC mode, DC-AC mode and AC-DC-AC mode. Other interconnection topological structures are generally a combination of these three typical structures.

[0073] The primary equipment configuration principles of the AC / DC system include:

[0074] ① Equipment capacity configuration should be determined based on factors such as load density, space resource conditions, coordination between upper and lower power grids, and overall economic efficiency;

[0075] ② Reasonable margins should be left for DC equipment and line capacity to ensure that the equipment meets operating requirements when load fluctuates or when power is transferred. At the same time, power reverse transmission or switching operation modes should be considered;

[0076] ③ Equipment selection should adhere to the principles of safety, reliability, economy, energy conservation, environmental protection and differentiation. Equipment with mature technology, low (no) maintenance, low loss, and expandable interfaces and functions should be used. The equipment should be tested by institutions with relevant qualifications. Areas with high requirements for power quality should appropriately improve the configuration standards of equipment;

[0077] ④ The configuration of AC equipment should comply with the provisions of DL / T 5729 "Technical Guidelines for Distribution Network Planning and Design";

[0078] ⑤ The energy router, converter, and DC transformer should be located close to the load center and installed indoors, and the capacity should be selected according to the load demand;

[0079] ⑥ The DC side switch selection should be coordinated with the converter / DC transformer. When the converter / DC transformer does not have the fault ride-through capability, a DC circuit breaker should be selected;

[0080] ⑦ When supplying power to DC loads with higher reliability requirements, more than two converters or DC transformers can be configured. When any converter or DC transformer is out of operation, the capacity of the remaining converters or DC transformers should meet the load power supply requirements.

[0081] The secondary configuration principles of the AC / DC system include:

[0082] 1) Configuration principles of protection system

[0083] ① AC / DC hybrid distribution network should be configured with protection devices according to its own characteristics and the principle of proximity, simplicity and overlapping zones;

[0084] ② The protection device should meet the requirements of reliability, selectivity, speed and sensitivity. The protection of various faults should have main protection and backup protection, and auxiliary protection can be added as needed;

[0085] ③ Any single component failure should not cause the protection device to malfunction or fail to operate, and there should be no protection dead zone under any operating conditions;

[0086] ④ AC and DC power distribution equipment should be equipped with abnormal operation monitoring and protection devices, and the protection functions and set values ​​should be dynamically configured and adjusted according to the operation mode;

[0087] ⑤ The protection of AC / DC hybrid distribution network should be divided into AC side protection area, AC / DC interconnection equipment protection area and DC side protection area. Faults in different protection areas should be cleared by the area concerned and should not affect the normal operation of other areas.

[0088] ⑥ The AC side protection area shall be equipped with relay protection and safety automatic devices in accordance with the provisions of GB / T 14285 "Technical Specifications for Relay Protection and Safety Automatic Devices", and the setting calculation of the relay protection device shall comply with the provisions of DL / T584 "3-110kV Power Grid Relay Protection Device Operation Setting Regulations";

[0089] ⑦ The connecting transformer in the protection area of ​​AC / DC interconnection equipment should adopt differential protection and body protection; the converter should be equipped with overcurrent protection, and bridge arm reactance differential protection can be added as needed; the protection configuration of the commutation reactor should be determined in accordance with GB / T14285;

[0090] ⑧ In addition to the ability to quickly cut off the fault of the equipment itself, the protection of DC equipment should also be able to quickly isolate external faults;

[0091] ⑨ The coordination of different protection areas shall comply with the following provisions:

[0092] a) When a fault occurs on the AC side, the AC side protection should selectively cut off the fault, and the protection action of the AC / DC interconnected equipment should be avoided, and the DC side protection should not be caused to malfunction;

[0093] b) The backup protection of AC lines should ensure sufficient sensitivity in the event of a fault at the end of the line and should be coordinated with the protection of AC and DC interconnection equipment.

[0094] 2) Automation control principle

[0095] ① The automation and informatization requirements of AC / DC hybrid distribution network should be based on the primary grid structure to achieve information collection, operation control and rapid fault handling of AC / DC distribution network. For areas with more complex control, AC / DC hybrid distribution network should be equipped with a coordinated control system;

[0096] ② The planning and design of the automation control system should meet the scale and application requirements of the distribution network in the next 5 to 10 years, and reasonably determine the system functions and hardware configuration solutions;

[0097] ③ The AC / DC hybrid distribution network automation control system should be reasonably configured according to the distribution network structure, communication mode, and real-time information volume requirements;

[0098] ④ The AC / DC hybrid distribution network automation control system should adopt an isolated, reliable, and highly anti-interference network structure;

[0099] ⑤ The AC / DC hybrid distribution network automation control system can adopt a standard universal software and hardware platform, can be based on an information exchange bus, and have the functions of external interactive graphics data, real-time data and historical data, can support the vertical and horizontal connection and layered application of data at all levels, and should comply with the configuration requirements of DL / T 814 "Distribution Automation System Functional Specification";

[0100] ⑥Automated information collection and transmission should comply with the provisions of GB / T 37138 "Guidelines for the Implementation of Security Level Protection of Power Information Systems".

[0101] S5. Based on the AC / DC power distribution system networking modes adapted to different typical scenarios constructed in steps S1 to S4, an AC / DC power distribution system networking method adapted to different typical scenarios is provided.

[0102] The basic requirement of the networking method is that all power supply points and load points of the power grid are connected, and no islands or isolated links should appear; no ring network should be formed in the network. The method is a radiation network repair method based on breadth-first search, which checks and repairs the connectivity and radiation of the generated network. For the network composed of known nodes on the line, a networking method is formed.

[0103] The specific steps of step S5 include:

[0104] like Figure 4 As shown in the figure, it is assumed that it is the DC distribution network architecture of a certain area. The solid line is the built DC line, and the dotted line is the DC corridor where the new line can be built. The DC corridor has 14 nodes, node 1 is the root node, nodes 1 to 4 are the built load nodes, and the remaining nodes are nodes to be built. Lines 1-2, 1-3, and 1-4 are built lines. Assuming that nodes 5, 8, 10, 11, and 13 are the access points of the optimized DC components, the process of these points forming a DC network is as follows:

[0105] (1) Initialize the networking failure flag signID = 0. Start traversal with node 1 as the root node, add the nodes visited in the traversal to the set Result = {1, 2, 3, 4}, and add the unvisited nodes in the line corridor to the set NotVisitNodes = {5, 8, 10, 11, 13};

[0106] (2) Take the first node in the unvisited node set, node 5, and search for the node set connected to node 5 by a DC corridor, namely AdjacentNodes = {3, 6, 7, 9, 10}. Determine the node set that can enable node 5 to access the established network after connecting to it, namely PossibleConnectingNodes = {3}. If there are multiple candidate access nodes, randomly select one as the connection point for the new node to access the existing network. In this example, the connection point of node 5 is node 3. Traverse the newly formed network and update the visited node set Result = {1, 2, 3, 4, 5} and the unvisited node set NotVisitNodes = {8, 10, 11, 12, 13}.

[0107] (3) Continue to take the first node in the set of unvisited nodes, node 8. If all the nodes connected to it are not in the established network, then put it at the last position of NotVisitNodes, NotVisitNodes = {10, 11, 12, 13, 8}, and the suspension count GZFlag of node 8 is increased by 1. After the remaining nodes are connected to the network, search for the access point of the node again.

[0108] (4) Continue to take the first node in NotVisitNodes to perform networking operations until the set of unvisited nodes is empty and the DC networking is completed. The network it forms is as follows: Figure 4 shown.

[0109] (5) If a node forms a ring network with existing nodes after access, then other nodes are selected from the nodes it is connected to. If all the nodes it is connected to cannot be networked, it is placed at the end of NotVisitNodes and its GZFlag is increased by 1. If a node still fails to access the existing network after being placed for 3 times, the networking fails and the networking failure flag signID is set to 1. In the particle swarm optimization calculation process, if a particle fails to network, the fitness value of the particle is set to inf, and the particle will not be selected as the optimal particle.

[0110] (6) The networking method is completed and the connection information of the formed network is generated.

[0111] Typical application scenarios of the AC / DC power distribution system adapted to different typical scenarios in step S5 include: DC power distribution in DC load concentration areas, DC power distribution in industrial parks, DC transformation of urban load centers, DC power distribution for renewable energy generation, low-voltage flexible interconnection of AC / DC power distribution systems, county-scale photovoltaic access, and wind, solar, and storage microgrids;

[0112] The DC power distribution in the DC load concentration area includes: DC power distribution in data centers, DC power distribution in electric vehicle charging and swapping facilities, and DC power distribution in residential buildings.

[0113] The present invention is further described below in conjunction with specific examples:

[0114] Example 1

[0115] This embodiment discloses a DC power distribution application scenario of a data center in a DC power distribution in a DC load concentration area, including the following steps:

[0116] Data centers mainly provide server data management services for various enterprises to ensure the security of various types of data. The main load of the data center is the server load. In addition, the data center server needs to maintain a constant temperature of 7 degrees Celsius all year round. The cooling load is also the main load of the data center. Considering that the main load of the data center is the DC server and the variable frequency cooling load, the conventional AC power access needs to go through the AC / DC link, so the large-scale DC load of the data center requires more reliable support from DC power access and DC distribution network.

[0117] S1. Determine the voltage level. The AC power supply uses 380 (400) V and the DC power supply uses ±375 V. This voltage level can power some large household appliances (such as air conditioners);

[0118] S2, now combined Figure 1 Describe the power supply structure of the data center;

[0119] Determine the busbar structure. Data centers have high requirements for the reliability of server power supply. It is recommended to use a single busbar segmented structure with two busbars interconnected. At the same time, each two busbars are equipped with a diesel generator as a backup power supply. The ATS switch is used to switch between the mains and diesel generators. Under normal circumstances, DC power supply is used, and the diesel generator is used as a backup to ensure high-reliability power supply for the server and to ensure that the server does not lose power under various circumstances.

[0120] S3. Determine the wiring method. Considering the difference in reliability between symmetrical unipolar and true bipolar power supply and the high reliability requirements of data centers, it is recommended to use true bipolar wiring;

[0121] S4. Determine the grounding method. Taking into account factors such as personal safety, power supply reliability, and electrochemical corrosion of the grounding grid by stray current at the grounding point, it is recommended that the low-voltage power system of the data center adopt an ungrounded method. At the same time, a low-voltage insulation monitoring system needs to be configured to promptly detect and eliminate single-point grounding events to ensure personal safety;

[0122] S5. Equipment configuration principles. The equipment configuration principles refer to the primary and secondary equipment configuration principles of the DC power distribution system, and should also comply with relevant standards such as the data center power supply system configuration standards.

[0123] Example 2

[0124] This embodiment discloses a DC power distribution application scenario of electric vehicle charging and swapping facilities in DC power distribution in a DC load concentration area, including the following steps:

[0125] S1. Determine the voltage level. According to the different charging speeds of electric vehicle chargers, the output voltage of electric vehicle chargers is currently between DC 200V and DC 700V. According to the DC voltage level sequence recommended by GB / T 35727, it is recommended to use ±375V voltage as the DC bus voltage of electric vehicle charging facilities. The DC / DC converter can be used in the middle to obtain voltages of various voltage levels.

[0126] S2, now combined Figure 2 The DC power distribution structure of electric vehicle charging and swapping facilities is explained.

[0127] Determine the busbar structure. Considering that the reliability requirements of electric vehicle charging and swapping facilities are generally average, the busbar structure can adopt a single busbar structure or a single busbar segmented structure.

[0128] S3. Determine the wiring method. Taking into account the technical economy, reliability and other requirements, in this application scenario, the inverter wiring method is recommended to use a symmetrical unipolar (pseudo-bipolar) structure; if the charging station is large, after technical and economic analysis, a true bipolar wiring method can also be used to provide a larger capacity and more voltage options.

[0129] S4. Determine the grounding method. Taking into account factors such as personal safety, power supply reliability, and electrochemical corrosion of the grounding grid by stray current at the grounding point, it is recommended that the DC power distribution of electric vehicle charging and swapping facilities adopt an ungrounded method. At the same time, a low-voltage insulation monitoring system needs to be configured to promptly detect and eliminate single-point grounding events to ensure personal safety.

[0130] S5. Equipment configuration principles. The equipment configuration principles refer to the primary and secondary equipment configuration principles of DC power distribution systems, and should also comply with relevant technical standards such as GB / T 36278.

[0131] Example 3

[0132] This embodiment discloses an application scenario of low-voltage flexible interconnection of AC and DC power distribution systems, including the following steps:

[0133] S1. Determine the voltage level. In this application scenario, flexible interconnection of AC distribution networks can be achieved by using flexible ring network control devices (flexible DC power electronic devices used to realize the operation of medium-voltage distribution network ring networks, divided into two ports, three ports, four ports, etc.), or by installing AC / DC converters at appropriate locations of the intended interconnected power grid. Considering that my country's AC medium and low voltage distribution networks are mainly 10kV and 380V, combined with objective factors such as technology maturity, equipment manufacturing difficulty and investment, the recommended voltage levels for the application scenario of AC distribution network zone interconnection are: AC10kV, 380V, DC750V.

[0134] S2, now combined Figure 3 The structure diagram of the low-voltage flexible internet of AC and DC power distribution systems is used to illustrate this.

[0135] For the use of two-port and three-port flexible ring network control devices to achieve AC distribution network partition interconnection, its typical grid structure mainly includes cable network-two-terminal type, cable network-three-terminal type, cable network-opening and closing station type, etc. The interconnection method can be equipped with AC380V / DC750V flexible interconnection devices in AC10kV / 380V distribution transformer room, connected to a 750V low-voltage ring network structure through flexible interconnection devices, and distributed photovoltaic, energy storage and charging piles are connected to the 750V DC bus to achieve load balancing and flow mutual assistance between different distribution transformers.

[0136] S3. Determine the wiring method. In this application scenario, the main purpose is to achieve the interconnection of AC distribution networks. Therefore, the pseudo-bipolar wiring method is recommended as the wiring method. For the application scenario of zone interconnection with very high reliability requirements, the true bipolar wiring method can also be used as appropriate.

[0137] S4. Determine the grounding method. In this application scenario, the grounding method needs to be determined based on factors such as the type of converter, whether there is a connecting transformer, and the grounding conditions on the AC and DC sides. For interconnected systems using two-level / three-level converters, it is recommended to use the DC side capacitor midpoint grounding method; for interconnected systems using MMC converters, it is recommended to use the connecting transformer midpoint grounding via a resistor or the DC side clamping resistor midpoint grounding method.

[0138] S5. Protection and control measures. The DC link is equipped with insulation monitoring devices and low-voltage DC bus protection, and the AC / DC interface converter has a bidirectional overcurrent protection function. The communication method uses optical fiber, RS485 or Ethernet. Configure a coordinated control system for station-level energy management, control interconnected devices, DC piles, distributed photovoltaics, and energy storage to achieve power regulation in different distribution rooms and different distribution transformers, ensure accurate regulation of DC pile charging and discharging power, and reduce the impact of randomness of electric vehicle charging and concentrated charging during peak hours on the public power grid.

[0139] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0140] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, 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 device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0141] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0142] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

Claims

1. A method for networking AC and DC power distribution systems suitable for different typical scenarios, characterized in that: The steps include: S1. Based on the grid structure of DC distribution network, build AC and DC distribution system networking modes suitable for different typical scenarios; S2. Based on the connection mode of DC distribution network, build AC / DC distribution system networking mode suitable for different typical scenarios; S3. Based on the grounding method of the DC distribution network, build an AC / DC distribution system networking mode suitable for different typical scenarios; S4. Based on the AC / DC interconnection mode and the configuration principles of the primary and secondary equipment of the system, build AC / DC distribution system networking modes suitable for different typical scenarios; S5. Based on the AC / DC power distribution system networking modes adapted to different typical scenarios constructed in steps S1 to S4, AC / DC power distribution system networking adapted to different typical scenarios is performed.

2. According to claim 1, a method for networking AC and DC power distribution systems suitable for different typical scenarios is characterized in that: The grid structure of the DC distribution network in step S1 includes: a typical grid structure of a medium-voltage AC / DC hybrid distribution network including a flexible ring network control device, a medium-voltage DC distribution network grid structure, and a low-voltage DC busbar structure; The typical grid structure of the medium voltage AC / DC hybrid distribution network containing the flexible ring network control device includes: a grid structure containing a two-terminal flexible ring network control device, and a grid structure containing a three-terminal flexible ring network control device; The medium voltage DC distribution network grid structure includes: a single-end radial structure, a single-end ring network structure, a multi-end radial structure, and a multi-end ring structure; The low voltage DC busbar structure includes: a single busbar structure, a double busbar structure, a layered busbar structure, and a redundant busbar structure.

3. According to claim 1, a method for networking AC and DC power distribution systems adapted to different typical scenarios is characterized in that: The connection mode of the DC power distribution network in step S2 includes: the connection mode of the converter of the DC power distribution system; Among them, the DC distribution system converter wiring forms include: single-pole structure and double-pole structure; The monopole structure includes: a symmetrical monopole structure and an asymmetrical monopole structure; The asymmetric monopole structure is divided into a monopole ground loop mode and a monopole metal loop mode; The bipolar structure includes a positive busbar, a negative busbar and a neutral line.

4. According to claim 1, a method for networking AC and DC power distribution systems adapted to different typical scenarios is characterized in that: The grounding method of the DC distribution network in step S3 includes: a medium voltage DC distribution network grounding method and a low voltage DC distribution network grounding method; Among them, the grounding methods of the medium-voltage DC distribution network include: the grounding method of the flexible DC transmission system and the typical grounding method of the medium-voltage DC distribution network; the grounding methods of the low-voltage DC distribution network include: low-voltage true bipolar connection and low-voltage pseudo bipolar connection.

5. The AC / DC power distribution system networking method adapted to different typical scenarios according to claim 1 is characterized in that: The AC / DC interconnection mode and the primary and secondary equipment configuration principles of the system in step S4 include: typical technical principles of AC / DC interconnection mode, typical interconnection mode of AC / DC power distribution system, primary equipment configuration principles of AC / DC system, and secondary configuration principles of protection and automation, metering and communication system.

6. The AC / DC power distribution system networking method adapted to different typical scenarios according to claim 1 is characterized in that: The specific steps of step S5 include: (1) Initialize the networking failure flag signID = 0; start traversal with node 1 as the root node, add the nodes visited during the traversal to the set Result = {1, 2, 3, 4}, and add the unvisited nodes in the line corridor to the set NotVisitNodes = {5, 8, 10, 11, 13}; (2) Take the first node in the unvisited node set, node 5, and search for the node set connected to node 5 by a DC corridor, AdjacentNodes = {3, 6, 7, 9, 10}. Determine the node set that can enable node 5 to access the established network after connecting to it, PossibleConnectingNodes = {3}. If there are multiple candidate access nodes, randomly select one as the connection point for the new node to access the existing network. In this example, the connection point of node 5 is node 3. Traverse the newly formed network and update the visited node set Result = {1, 2, 3, 4, 5}. The unvisited node set NotVisitNodes={8,10,11,12,13}; (3) Continue to take the first node in the unvisited node set, node 8. If all the nodes connected to it are not in the established network, then put it at the last position of NotVisitNodes, NotVisitNodes = {10, 11, 12, 13, 8}, and increase the shelving count GZFlag of node 8 by 1. After the remaining nodes are connected to the network, search for the access point of the node again. (4) Continue to take the first node in NotVisitNodes to perform networking operations until the set of unvisited nodes is empty and the DC networking is completed. The network it forms is shown in Figure 4.

3. (5) If a node forms a ring network with existing nodes after access, then other nodes are selected from the nodes it is connected to. If all the nodes it is connected to cannot be networked, it is placed at the end of NotVisitNodes and its GZFlag is increased by 1. If a node still fails to access the existing network after being placed for 3 times, the networking fails and the networking failure flag signID is set to 1. In the particle swarm optimization calculation process, if a particle fails to network, the fitness value of the particle is set to inf, and the particle will not be selected as the optimal particle. (6) The networking method is completed and the connection information of the formed network is generated.

7. The AC / DC power distribution system networking method adapted to different typical scenarios according to claim 1 is characterized in that: The AC / DC power distribution system adapted to different typical scenarios in step S5 includes: DC power distribution in DC load concentration areas, DC power distribution in industrial parks, DC transformation of urban load centers, DC power distribution for renewable energy generation, low-voltage flexible interconnection of AC / DC power distribution systems, county-scale photovoltaic access, and wind, solar, and storage microgrids; The DC power distribution in the DC load concentration area includes: DC power distribution in data centers, DC power distribution in electric vehicle charging and swapping facilities, and DC power distribution in residential buildings.

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