A flexible interconnection topology design method and system for balancing different source-load structures between distribution stations

Abstract

The present invention discloses a flexible interconnection topology design method and system for balancing different source-load structures between distribution stations, the method comprising: arranging multiple AC loads at the outlet of the low-voltage side of the transformer; connecting multiple charging devices to a DC bus, and interconnecting and supplying each other through a single bus structure; configuring an energy storage unit with a preset capacity for the charging device; connecting multiple data centers to the DC bus, and connecting multiple data centers using a bus segmentation structure, and interconnecting two adjacent data centers through a DC bus circuit breaker; configuring an energy storage unit for each segmented bus; connecting the energy storage unit to the DC bus through a DC / DC converter; connecting multiple load users to the DC bus, and using a common DC bus structure for multiple load users; connecting an AC outlet on the low-voltage side of the transformer to a DC ring network through an AC / DC converter, and the AC / DC converter adopts a pseudo-bipolar wiring form.

Description

Technical Field

[0001] The present invention relates to the technical field of low-voltage AC / DC hybrid power distribution, and more specifically, to a method and system for balancing load rates between stations with different economic structures in the same area. Background Art

[0002] The distribution substation is one of the important components of the power system, which directly affects the local economic development and the daily life quality of users. Most of the existing low-voltage substations adopt the form of single transformer and single line power supply, which has low reliability, and the power supply between each substation is independent and lacks unified management and control. In rural areas, with the construction of beautiful villages and the advancement of the government's rural electrification project, the capacity of access to public transformers has increased, and the requirements of users under these substations for power supply reliability have increased day by day. The original single power supply has been difficult to meet the growing power consumption capacity and high reliability requirements. In addition, due to different economic structures, seasonal load fluctuations often occur in the same area, which leads to large differences in the load rate of the substation. If it is solved blindly by increasing capacity and deploying points, the remaining capacity of the substation with lighter load in the area is still not fully utilized. And with the increasing number of DC loads such as electric vehicle charging stations, data centers, DC home appliances, and communication equipment, as well as the high proportion and large-capacity decentralized access of DC distributed power sources such as photovoltaics, the current distribution network source-load-storage DC characteristics are becoming more and more obvious. The access of DC distributed power sources and loads increases the conversion links and grid connection difficulties of the power grid, directly affecting the power quality and operation control of the existing distribution substations, while reducing the overall operation efficiency of the system. The access location and capacity of residential photovoltaic and large-scale photovoltaic in some areas are uncontrollable, which will affect the quality of power and power fluctuations. If the absorption problem of high-penetration photovoltaic cannot be solved, it will also cause power backflow. In addition, the disorderly access of large-scale electric vehicles will also cause insufficient capacity of distribution areas and some power lines, requiring a large amount of capital to increase capacity and expand.

[0003] Therefore, a technology is needed to balance the load rates between stations with different economic structures in the same region. Summary of the invention

[0004] The technical solution of the present invention provides a flexible interconnection topology design method and system for balancing different source-load structures between distribution stations, so as to solve the problem of how to balance the load rates between stations with different economic structures in the same area.

[0005] In order to solve the above problems, the present invention provides a flexible interconnection topology design method for balancing different source-load structures between distribution stations, the method comprising:

[0006] Multiple AC loads are set at the low-voltage side outlet of the transformer;

[0007] Connect multiple charging devices to the DC bus, and interconnect and supply each other through a single bus structure; the charging devices are equipped with energy storage units with preset capacities;

[0008] Connect multiple data centers to the DC bus. The multiple data centers are connected using a bus segmentation structure. Two adjacent data centers are interconnected through a DC bus circuit breaker. Each segmented bus is configured with an energy storage unit. The energy storage unit is connected to the DC bus through a DC / DC converter.

[0009] Connect multiple load users to the DC bus, and multiple load users adopt a common DC bus structure;

[0010] An AC outgoing line on the low-voltage side of the transformer is connected to the DC ring network through an AC / DC converter, and the AC / DC converter adopts a pseudo-bipolar wiring form.

[0011] Preferably, the method further comprises: reserving a plurality of DC interfaces for the DC bus.

[0012] Preferably, the method further comprises: the circuit breaker is in a closed state.

[0013] Preferably, it also includes: a plurality of AC interfaces are reserved at the low-voltage side outlet of the transformer.

[0014] Based on another aspect of the present invention, the present invention provides a flexible interconnection topology design system for balancing different source-load structures between distribution stations, the system comprising:

[0015] The initial unit is used to set multiple AC loads at the outlet of the low-voltage side of the transformer;

[0016] A configuration unit is provided, which is used to connect multiple charging devices to a DC bus, and the multiple charging devices are interconnected and supplied to each other through a single bus structure; the charging devices are configured with energy storage units of preset capacity; multiple data centers are connected to the DC bus, and the multiple data centers are connected using a bus segmentation structure, and two adjacent data centers are interconnected through a DC bus circuit breaker; each segmented bus is configured with an energy storage unit; the energy storage unit is connected to the DC bus through a DC / DC converter; multiple load users are connected to the DC bus, and multiple load users use a common DC bus structure; an AC output line on the low-voltage side of the transformer is connected to the DC ring network through an AC / DC converter, and the AC / DC converter uses a pseudo-bipolar wiring form.

[0017] Preferably, the configuration unit is further used to: reserve a plurality of DC interfaces for the DC bus.

[0018] Preferably, the configuration unit is further used for: the circuit breaker is in a closed state.

[0019] Preferably, the configuration unit is also used to reserve multiple AC interfaces at the low-voltage side outlet of the transformer.

[0020] The technical solution of the present invention realizes balancing the load rate between substations with different economic structures in the same area by providing a structural topology for flexible interconnection of low-voltage distribution substations. The structural topology proposed by the present invention can be applied to large-scale charging pile access, data center access scenarios, and to cope with the increase in terminal electrification rate such as "coal to electricity", seasonal load fluctuations and flexible interconnection of high-penetration distributed photovoltaic access substations, and reserves charging piles, photovoltaics, and energy storage interfaces on the DC side; when the system is operating normally, it adjusts the flow, balances the load, and realizes dynamic capacity expansion of the substation; when a single substation fails, its subordinate important loads can be supplied by other substations or energy storage devices to improve power supply reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] A more complete understanding of exemplary embodiments of the present invention may be obtained by referring to the following drawings:

[0022] Figure 1 A schematic diagram of a low-voltage distribution station area flexible interconnection system according to a preferred embodiment of the present invention;

[0023] Figure 2 A schematic diagram of the structural topology of a flexible interconnection system in a large-scale fast charging station access scenario according to a preferred embodiment of the present invention;

[0024] Figure 3 A schematic diagram of the topology of the flexible interconnection system in the data center access scenario according to a preferred embodiment of the present invention;

[0025] Figure 4 A schematic diagram of the structural topology of a flexible interconnection system in a substation under a scenario of seasonal load fluctuation and high-proportion distributed photovoltaic access according to a preferred embodiment of the present invention;

[0026] Figure 5 This is a schematic diagram of an AC outgoing line on the low voltage side according to a preferred embodiment of the present invention;

[0027] Figure 6 A flow chart of a method for balancing load rates between stations with different economic structures in the same region according to a preferred embodiment of the present invention;

[0028] Figure 7 This is a system structure diagram for balancing the load rates between stations with different economic structures in the same area according to a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0029] Now, exemplary embodiments of the present invention are described with reference to the accompanying drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to disclose the present invention in detail and completely and to fully convey the scope of the present invention to those skilled in the art. The terms used in the exemplary embodiments shown in the accompanying drawings are not intended to limit the present invention. In the accompanying drawings, the same units / elements are marked with the same reference numerals.

[0030] Unless otherwise specified, the terms (including technical terms) used herein have the commonly understood meanings to those skilled in the art. In addition, it is understood that the terms defined in commonly used dictionaries should be understood to have the same meanings as those in the context of the relevant fields, and should not be understood as idealized or overly formal meanings.

[0031] The present invention provides a structural topology for flexible interconnection of low-voltage distribution substations to achieve load balance between substations with different economic structures in the same region. The invention can be applied to large-scale charging pile access, data center access scenarios, and to address the increase in terminal electrification rates such as coal-to-electricity conversion, seasonal load fluctuations, and flexible interconnection and mutual supply of high-penetration distributed photovoltaic access substations, and reserve charging piles, photovoltaics, and energy storage interfaces on the DC side.

[0032] The structural topology of the present invention is mainly used in system conditions where the load rate of the substations is unbalanced in different scenarios. Based on the goals of achieving load balancing between substations, dynamic capacity expansion and energy optimization, the flexible interconnected structural topology of the substations will lay the foundation for the application of multi-energy scheduling technology for the combination of power, heating and cooling networks in the region, and realize the comprehensive utilization and complementary advantages of different substations and different types of energy. Figure 1 The low-voltage distribution station area flexible interconnection system shown is taken as an example to illustrate the content and effectiveness of the present invention.

[0033] exist Figure 1 In the system, each distribution station area is interconnected on the DC side through an AC / DC converter. The DC bus can be connected to energy storage devices, distributed power sources such as photovoltaics, and energy users such as DC fast charging piles, data centers, and smart homes. The original AC load is still retained at the low-voltage side outlet of the transformer.

[0034] Figure 2 For the flexible interconnection system structure topology of the substation under the large-scale fast charging station access scenario, considering the general requirements of electric vehicle charging and swapping equipment for power supply reliability, a single busbar structure is adopted for interconnection and supply. While connecting to the DC fast charging pile, it is equipped with energy storage of appropriate capacity to guide orderly charging and fill the valley with peak loads, which can effectively alleviate the peak load rate of the substation and realize advanced applications to a certain extent.

[0035] Figure 3For the flexible interconnection system structure topology of the substation in the data center access scenario, considering the high requirements of the data center for power supply reliability, and considering the comprehensive economy and reliability, the present invention adopts a single bus segmented structure. The busbars at both ends are interconnected through a DC bus tie circuit breaker, and the circuit breaker is in a normally closed state. Each bus section needs to be configured with energy storage or diesel generator as a backup power supply. The energy storage can be directly connected to the DC bus through a DC / DC converter, and the diesel generator is connected to the substation AC low-voltage bus through an ATS.

[0036] Figure 4 It is a flexible interconnection system structure topology for the seasonal load fluctuation and high proportion of distributed photovoltaic access scenarios. Its load is mainly composed of small agricultural industrial loads, tourism, irrigation, tea-making loads, and ordinary residential electricity loads. The power load does not have high requirements for power supply reliability. The interconnection and mutual supply mainly solve the problems of unbalanced load rate and clean energy consumption in the substation. The structure of common DC bus is adopted. By configuring energy storage of corresponding capacity, the power supply reliability of important loads in the substation is improved while improving the clean energy consumption efficiency in the substation, and realizing the optimized operation and regulation of source-grid-load-storage.

[0037] Figure 5 A multi-terminal ring structure topology for the flexible interconnection system in the substation under high-reliability power supply demand scenario. Figure 5 The AC outgoing line on the low-voltage side is connected to the DC ring network through an AC / DC converter. The converter adopts a pseudo-bipolar connection form. The voltage of each DC bus section is ±375V, and the inter-stage voltage is 750V. This structure is suitable for scenarios where the distance between adjacent substations is long, the transfer power is small, the power supply reliability is high, and each substation has a high proportion of distributed power sources and loads connected.

[0038] Figure 6 This is a flow chart of a method for balancing the load rate between stations with different economic structures in the same region according to a preferred embodiment of the present invention. Figure 6 As shown, the present invention provides a method for balancing the load rate between stations with different economic structures in the same area, the method comprising:

[0039] Step 601: multiple AC loads are set at the low-voltage side outlet of the transformer; preferably, it also includes: multiple AC interfaces are reserved at the low-voltage side outlet of the transformer.

[0040] Step 602: multiple charging devices are connected to the DC bus, and the multiple charging devices are interconnected and supplied to each other through a single bus structure; the charging devices are configured with energy storage units of preset capacity;

[0041] Step 603: multiple data centers are connected to the DC bus. The multiple data centers are connected using a bus segmentation structure. Two adjacent data centers are interconnected via a DC bus circuit breaker. Each segmented bus is configured with an energy storage unit. The energy storage unit is connected to the DC bus via a DC / DC converter. Preferably, the circuit breaker is in a closed state.

[0042] Step 604: multiple load users are connected to the DC bus, and the multiple load users adopt a common DC bus structure;

[0043] Step 605: connect an AC outgoing line on the low-voltage side of the transformer to the DC ring network through an AC / DC converter, where the AC / DC converter adopts a pseudo-bipolar connection form.

[0044] Preferably, the present invention further comprises: reserving a plurality of DC interfaces for the DC bus.

[0045] When the system is operating normally, the present invention can realize flow regulation, load balancing, and dynamic capacity expansion of substations; when a single substation fails, its subordinate important loads can be supplied by other substations or energy storage devices, thereby improving power supply reliability.

[0046] Compared with conventional capacity expansion and deployment solutions, the present invention reserves DC interfaces for energy storage, photovoltaics, charging piles, etc., which can improve the power supply level and interactive capabilities of diversified integrated substations, improve power supply reliability, and is one of the important ways to achieve regional autonomy.

[0047] The present invention provides a structural topology for flexible interconnection of low-voltage distribution stations, which can be applied to large-scale charging pile access, data center access scenarios, and flexible interconnection to cope with seasonal load fluctuations and high-penetration distributed photovoltaic access stations, and reserves charging pile, photovoltaic, and energy storage interfaces on the DC side. When the system of the present invention is operating normally, the topology can achieve flow regulation, load balancing, and dynamic capacity expansion of the station; when a single station fails, its subordinate important loads can be supplied by other stations or energy storage devices, thereby improving power supply reliability. Compared with conventional capacity expansion and point distribution solutions, the present invention reserves DC interfaces for energy storage, photovoltaics, charging piles, etc., which can improve the power supply level and interactive capabilities of the diversified integrated stations and improve power supply reliability.

[0048] Figure 7 This is a system structure diagram for balancing the load rates between stations with different economic structures in the same area according to a preferred embodiment of the present invention. Figure 7 As shown, the present invention provides a system for balancing the load rate between stations with different economic structures in the same area, and the system includes:

[0049] Initial unit 701, used to set multiple AC loads at the low-voltage side outlet of the transformer;

[0050] Configuration unit 702 is used to connect multiple charging devices to the DC bus, and the multiple charging devices are interconnected and supplied to each other through a single bus structure; the charging devices are configured with energy storage units of preset capacity; multiple data centers are connected to the DC bus, and the multiple data centers are connected using a bus segmentation structure, and two adjacent data centers are interconnected through a DC bus circuit breaker; each segmented bus is configured with an energy storage unit; the energy storage unit is connected to the DC bus through a DC / DC converter; multiple load users are connected to the DC bus, and multiple load users use a common DC bus structure; an AC output line on the low-voltage side of the transformer is connected to the DC ring network through an AC / DC converter, and the AC / DC converter uses a pseudo-bipolar wiring form.

[0051] Preferably, the configuration unit is further used to: reserve a plurality of DC interfaces for the DC bus.

[0052] Preferably, the configuration unit is further configured to: the circuit breaker is in a closed state.

[0053] Preferably, the configuration unit is also used to: reserve multiple AC interfaces at the low-voltage side outlet of the transformer.

[0054] The invention has been described above with reference to a few embodiments. However, it is readily apparent to a person skilled in the art that other embodiments than the ones disclosed above are equally within the scope of the invention, as defined by the appended patent claims.

[0055] Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a / said / the [means, components, etc.]" are to be openly interpreted as at least one instance of the means, components, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not necessarily have to be performed in the exact order disclosed, unless explicitly stated otherwise.

Claims

1. A flexible interconnection topology design method for balancing different source-load structures between distribution stations, the method comprising: Multiple AC loads are set at the low-voltage side outlet of the transformer; Connect multiple charging devices to the DC bus, and interconnect and supply each other through a single bus structure; the charging devices are equipped with energy storage units with preset capacities; Connect multiple data centers to a DC bus, connect multiple data centers using a bus segmentation structure, and interconnect two adjacent data centers via a DC bus circuit breaker; configure an energy storage unit on each segmented bus; connect the energy storage unit to the DC bus via a DC / DC converter; reserve multiple DC interfaces on the DC bus; and the circuit breaker is in a closed state; Connect multiple load users to the DC bus, and multiple load users adopt a common DC bus structure; An AC outgoing line on the low-voltage side of the transformer is connected to the DC ring network through an AC / DC converter, and the AC / DC converter adopts a pseudo-bipolar wiring form.

2. The method according to claim 1, further comprising: Multiple AC interfaces are reserved at the low-voltage side outlet of the transformer.

3. A flexible interconnection topology design system for balancing different source-load structures between distribution stations, the system comprising: The initial unit is used to set multiple AC loads at the outlet of the low-voltage side of the transformer; A configuration unit is used to connect multiple charging devices to the DC bus, and the multiple charging devices are interconnected and supplied to each other through a single bus structure; the charging devices are configured with energy storage units of preset capacity; multiple data centers are connected to the DC bus, and multiple data centers are connected using a bus segmentation structure, and two adjacent data centers are interconnected through a DC bus circuit breaker; each segmented bus is configured with an energy storage unit; the energy storage unit is connected to the DC bus through a DC / DC converter; multiple load users are connected to the DC bus, and multiple load users use a common DC bus structure; an AC output line on the low-voltage side of the transformer is connected to the DC ring network through an AC / DC converter, and the AC / DC converter adopts a pseudo-bipolar wiring form; The configuration unit is also used to: reserve multiple DC interfaces for the DC bus; The configuration unit is also used to: the circuit breaker is in a closed state.

4. According to the system of claim 3, the configuration unit is also used to: reserve multiple AC interfaces at the low-voltage side outlet of the transformer.

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