Direct-current power supply system, control method thereof and energy storage station

Abstract

A DC power supply system, a control method thereof and an energy storage station belong to the technical field of power electronics, and comprise a plurality of energy storage modules, a plurality of first switches, a plurality of second switches, a DC bus and a power supply circuit. The energy storage modules are connected with the first ends of the first switches in a one-to-one correspondence mode. The second ends of the first switches are connected with the first ends of the second switches in a one-to-one correspondence mode through the first nodes. The second end of each second switch is connected to the direct current bus; the power supply circuit converts the voltage of one of the first nodes or the voltage of the direct current bus into a power supply voltage so as to supply power to secondary equipment; therefore, the direct-current power supply system is provided to meet the power supply requirement of the secondary equipment of the energy storage station, the power supply cost is reduced, and the difficulty of insulation and voltage resistance design is reduced.

Description

Technical Field

[0001] The present application belongs to the field of power electronics technology, and in particular relates to a direct current power supply system and a control method thereof, and an energy storage station. Background Art

[0002] The architecture for powering secondary equipment primarily relies on mains electricity, with power conversion modules converting AC power to DC for powering devices or user-side equipment. However, this solution only addresses the AC power supply architecture and doesn't consider valve tower energy storage systems (such as energy storage stations) as a power source for the high-voltage grid, rather than using mains electricity.

[0003] The secondary equipment in an energy storage station plays a crucial role in communication, monitoring and regulation, and safety protection. Therefore, ensuring power supply for these critical functions is the prerequisite and foundation for all of these. While traditional mains power generation is simple and mature, its application in some valve tower energy storage systems, powered by high-voltage grid voltage, presents limitations. This results in high transformer hardware costs and difficulty designing insulation withstand voltage on the high-voltage grid side. Consequently, ensuring continuous power supply to the secondary equipment becomes a primary concern.

[0004] Therefore, it is urgent to provide a DC power supply system to meet the power supply needs of the secondary equipment of the energy storage station. Summary of the Invention

[0005] In view of the above problems, the present application provides a DC power supply system and an energy storage station, aiming to solve the problem that the relevant power supply system cannot meet the power supply requirements of the secondary equipment of the energy storage station through DC power supply.

[0006] In a first aspect, the present application provides an embodiment of the present application providing a DC power supply system, the DC power supply system comprising a plurality of energy storage modules, a plurality of first switches, a plurality of second switches, a DC bus, and a power supply circuit;

[0007] Each of the energy storage modules is connected to the first end of each of the first switches in a one-to-one correspondence;

[0008] The second end of each first switch is connected to the first end of each second switch via each first node in a one-to-one correspondence;

[0009] The second end of each second switch is connected to the DC bus;

[0010] The power supply circuit is connected to each of the first nodes and the DC bus, and is configured to convert the voltage of one of the first nodes or the voltage of the DC bus into a power supply voltage to power a secondary device.

[0011] In the technical solution of the embodiment of the present application, since the power supply circuit is connected to each first node and the DC bus, the voltage of one of the first nodes or the voltage of the DC bus is converted into a supply voltage to power the secondary equipment, that is, the power supply point of the secondary equipment is placed at the positive and negative ends of the energy storage module and the bus end of the DC bus, the AC power supply point of the mains is eliminated, and the traditional mains power supply architecture is abandoned. The power of the energy storage module of the energy storage station itself is used to power the secondary equipment, reducing the power supply cost, and only the insulation and voltage resistance design needs to be done on the energy storage module, which reduces the difficulty of the insulation and voltage resistance design.

[0012] In some embodiments, the DC power supply system further comprises:

[0013] an energy storage converter connected to the DC bus and configured to convert AC power into input DC power and transmit the input DC power to the DC bus;

[0014] The power supply circuit is specifically configured to convert the input direct current into the supply voltage to power the secondary device.

[0015] By adopting the above solution, it is achieved that when AC power is input from the grid side, power is generated through the AC side.

[0016] In some embodiments, the secondary device includes a battery management system;

[0017] The battery management system is connected to the power supply circuit and each of the second switches, and is configured to control each of the second switches to be closed after being powered on by the power supply voltage.

[0018] By adopting the above solution, after the AC side is powered on, each energy storage module is connected to the DC bus, thereby connecting each energy storage module to the power grid and operating normally.

[0019] In some embodiments, the power supply circuit is specifically configured to convert the voltage of the DC bus into a power supply voltage in response to each second switch being closed, so as to power a secondary device.

[0020] By adopting the above solution, when each energy storage module is connected to the power grid and operates normally, the DC power output by each energy storage module is converged to the DC bus, and the DC bus is used as the power supply point for secondary equipment, thereby improving the balanced control capability of each energy storage module.

[0021] In some embodiments, the power supply circuit is specifically configured to convert the voltage of one of the first nodes into a supply voltage in response to each of the second switches being turned off, so as to power a secondary device;

[0022] The secondary equipment includes a battery management system and an energy management system;

[0023] The energy management system is connected to the energy storage converter and is configured to output a start signal in response to the shutdown and start instructions of the alternating current;

[0024] The battery management system is connected to the energy management system, the power supply circuit and each of the second switches, and is configured to control each of the second switches to be closed according to the start signal.

[0025] By adopting the above solution, in the absence of AC power access, a black start of the DC power supply system is achieved by using one of the first nodes as a power supply point for secondary equipment. After the black start, the battery management system and the energy management system control the closure of each second switch to connect each energy storage module to the power grid and ensure normal operation.

[0026] In some embodiments, the power supply circuit is specifically configured to convert the voltage of the DC bus into a power supply voltage in response to each second switch being closed, so as to power a secondary device.

[0027] By adopting the above solution, each energy storage module is connected to the power grid. Under normal operation, the DC power output by each energy storage module is converged to the DC bus, and the DC bus is used as the power supply point for secondary equipment, thereby improving the balanced control capability of each energy storage module.

[0028] In some embodiments, the power supply circuit includes a first power circuit, a plurality of second power circuits, and a power distribution circuit;

[0029] The first power circuit is connected to the DC bus and configured to convert the voltage of the DC bus into a first voltage;

[0030] Each of the second power circuits is connected to each of the first nodes in a one-to-one correspondence, and is configured to convert the voltage of each of the first nodes into a corresponding second voltage;

[0031] A power distribution circuit is connected to the first power circuit and multiple second power circuits, and is configured to convert the first voltage into the supply voltage in response to the difference between each second voltage minus the first voltage being less than or equal to a first preset voltage; and in response to the difference between the second voltage minus the first voltage being greater than the first preset voltage, convert the second voltage with the largest voltage value into the supply voltage.

[0032] By adopting the above solution, power is drawn from the DC bus first. When the voltage of the DC bus is insufficient, power is drawn from the energy storage module with the highest voltage, achieving voltage balance among the energy storage modules and improving system utilization and reliability.

[0033] In some embodiments, the secondary device includes a battery management system;

[0034] The battery management system is connected to each of the energy storage modules, each of the second power circuits, and the power distribution circuit, and is configured to control the second power circuit connected to a target energy storage module to stop working, wherein the target energy storage module is the energy storage module with a power level less than a preset value.

[0035] By adopting the above solution, when the power of the energy storage module is less than a preset value, the second power circuit corresponding to the energy storage module stops working, thereby preventing over-discharge of the energy storage module and improving system reliability.

[0036] In some embodiments, the power distribution circuit includes a first diode, a plurality of second diodes, and a plurality of third diodes;

[0037] The anode of the first diode constitutes the first voltage input terminal of the power distribution circuit and is connected to the first power circuit to receive the first voltage;

[0038] The second diodes are respectively configured as second voltage input terminals of the power distribution circuit and are connected to the second power circuits in a one-to-one correspondence to access the second voltages.

[0039] The cathode of each second diode is connected to the anode of each third diode in a one-to-one correspondence;

[0040] The cathode of each of the third diodes is connected to the cathode of the first diode and constitutes a power supply voltage output end of the power distribution circuit. The power supply voltage output end is connected to the secondary device to output the power supply voltage.

[0041] By adopting the above solution, power is taken from the DC bus first through the circuit topology. When the voltage of the DC bus is insufficient, power is taken from the energy storage module with the highest voltage. This implementation method does not require software configuration, has high reliability and low cost.

[0042] In some embodiments, the first power circuit and the second power circuit each include a power module, and the power module includes a third switch, a fourth diode, an inductor, and a capacitor;

[0043] The first end of the third switch constitutes a voltage input end of the power module, and is connected to the DC bus or the first node to receive the voltage of the DC bus or the voltage of the first node;

[0044] The second end of the third switch is connected to the cathode of the fourth diode and the first end of the inductor;

[0045] The second end of the inductor and the first end of the capacitor are connected together to form a voltage output end of the power module, and the voltage output end of the power module is connected to the power distribution circuit to output the first voltage or the second voltage;

[0046] The second end of the capacitor and the anode of the fourth diode are connected to the power ground.

[0047] By adopting the above solution, the power circuit is simple and reliable, and has a sleep and stop working function.

[0048] The present application also provides a control method for the DC power supply system, including:

[0049] Get the voltage of the DC bus;

[0050] When the voltage of the DC bus is greater than a second preset voltage, converting the voltage of the DC bus into a supply voltage to supply power to a secondary device; the secondary device includes a battery management system;

[0051] When the voltage of the DC bus is less than or equal to a second preset voltage, converting the voltage of one of the first nodes into a power supply voltage to supply power to the secondary device;

[0052] When each of the second switches is closed, the voltage of the DC bus is converted into the supply voltage to supply power to the secondary device; wherein each of the second switches is controlled to be closed by the battery management system after power-on.

[0053] By adopting the above scheme, when the voltage of the DC bus is greater than the second preset voltage, power is taken through the DC bus; when the voltage of the DC bus is less than or equal to the second preset voltage, power is taken through one of the first nodes, that is, power supply can be achieved in various scenarios during AC side power-up, black start and continuous operation.

[0054] In some embodiments, the power supply circuit includes a first power circuit, a plurality of second power circuits, and a power distribution circuit;

[0055] The first power circuit is connected to the DC bus and configured to convert the voltage of the DC bus into a first voltage;

[0056] Each of the second power circuits is connected to each of the first nodes in a one-to-one correspondence, and is configured to convert the voltage of each of the first nodes into a second voltage;

[0057] a power distribution circuit connected to the first power circuit and a plurality of the second power circuits, and configured to, in response to a difference between each of the second voltages minus the first voltage being less than or equal to a first preset voltage, convert the first voltage into the supply voltage; and, in response to a difference between each of the second voltages minus the first voltage being greater than the first preset voltage, convert the second voltage having the largest voltage value into the supply voltage;

[0058] The control method further includes:

[0059] Obtaining the power of each of the energy storage modules;

[0060] Marking the energy storage module whose power is less than a preset value as a target energy storage module;

[0061] The second power circuit connected to the target energy storage module is controlled to stop working.

[0062] By adopting the above solution, when the power of the energy storage module is less than a preset value, the second power circuit corresponding to the energy storage module stops working, thereby preventing over-discharge of the energy storage module and improving system reliability.

[0063] In a second aspect, an embodiment of the present invention further provides an energy storage station, which includes the above-mentioned DC power supply system.

[0064] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present application. The same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0066] Figure 1 A schematic structural diagram of a DC power supply system provided in one embodiment of the present application;

[0067] Figure 2 Another structural diagram of a DC power supply system provided in one embodiment of the present application;

[0068] Figure 3 Another structural diagram of a DC power supply system provided in one embodiment of the present application;

[0069] Figure 4Another structural diagram of a DC power supply system provided in one embodiment of the present application;

[0070] Figure 5 Another structural diagram of a DC power supply system provided in one embodiment of the present application;

[0071] Figure 6 A schematic circuit diagram of a power distribution circuit in a DC power supply system provided in one embodiment of the present application;

[0072] Figure 7 A schematic circuit diagram of a power module in a DC power supply system provided in one embodiment of the present application;

[0073] Figure 8 Another structural schematic diagram of a DC power supply system provided in one embodiment of the present application. DETAILED DESCRIPTION

[0074] The following embodiments of the technical solution of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only examples and are not intended to limit the scope of protection of the present application.

[0075] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0076] In the description of the embodiments of this application, the technical terms "first" and "second" are used only to distinguish different objects and should not be understood to indicate or imply relative importance or implicitly specify the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0077] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0078] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0079] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0080] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0081] In the description of the embodiments of the present application, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; internal connections between two components or interactions between two components. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present application based on specific circumstances.

[0082] Currently, market developments indicate that energy storage systems are becoming increasingly widespread. They are widely used in transmission and distribution grids. As their application areas continue to expand, market demand for them is also growing.

[0083] With the widespread application of energy storage power systems and transmission and distribution networks, solving the power supply problem of secondary equipment has become a current social issue. The safety and reliability of the power supply of secondary equipment have attracted attention. The relevant energy storage power supply system includes a mains network and N load power supply devices. Each load power supply device is connected to the mains network through an AC power supply network. Each load power supply device includes an energy storage module, a power conversion module and a control module. The control modules of each load power supply device communicate with each other and can receive the relevant power parameters of each load power supply device. According to the relevant power parameters of all the load power supply devices, power control judgment and calculation are performed. When it is detected according to the judgment and calculation results that the load power supply device corresponding to the control module needs to transfer power to the load power supply device with insufficient power, the energy storage module is controlled to output power to the AC power supply network to supply energy to the load power supply device with insufficient power through the AC power supply network. However, this energy storage power supply system requires a dedicated energy storage module to be separately set up, and insulation withstand voltage design needs to be done on the mains network side. The power supply cost is high and the insulation withstand voltage design is difficult.

[0084] In order to solve the problems of high power supply costs and difficult insulation withstand voltage design, the research found that the power of the energy storage station's own energy storage modules can be used to power the secondary equipment in the design, and power can be drawn from the positive and negative terminals of the energy storage modules and the busbar end of the DC bus to power the secondary equipment, thereby reducing power supply costs and the difficulty of insulation withstand voltage design.

[0085] According to some embodiments of the present application, referring to Figure 1 , Figure 1 A schematic diagram of the structure of a DC power supply system provided by an embodiment of the present application is shown. For ease of explanation, only the parts related to this embodiment are shown, which are detailed as follows:

[0086] The DC power supply system includes a plurality of energy storage modules 11 , a plurality of first switches K1 , a plurality of second switches K2 , a DC bus, and a power supply circuit 12 .

[0087] Each energy storage module 11 is connected to the first end of each first switch K1 in a one-to-one correspondence.

[0088] The second end of each first switch K1 is connected to the first end of each second switch K2 via each first node A in a one-to-one correspondence.

[0089] The second end of each second switch K2 is connected to the DC bus.

[0090] The power supply circuit 12 is connected to each first node A and the DC bus, and is configured to convert the voltage of one of the first nodes A or the voltage of the DC bus into a power supply voltage to power the secondary device 13.

[0091] It is understood that the energy storage module 11 includes a battery module, which contains battery cells and components such as copper bars or wiring harnesses for high-voltage connections. The first switch K1 can be a manually controllable switch device. The second switch K2 can be a high-voltage contactor or relay. The relay can be an electromagnetic relay, an induction relay, an electric relay, an electronic relay, etc., without limitation. The high-voltage contactor can be an electromagnetic contactor, a permanent magnet contactor, etc., without limitation.

[0092] exist Figure 1 The DC power supply system shown works as follows:

[0093] In response to the voltage of the DC bus being greater than a second preset voltage, converting the voltage of the DC bus into a power supply voltage to power the secondary device 13; the secondary device 13 includes a battery management system 131;

[0094] In response to the voltage of the DC bus being less than or equal to a second preset voltage, converting the voltage of one of the first nodes A into a power supply voltage to power the secondary device 13;

[0095] After the battery management system 131 is powered on, it controls each second switch K2 to be closed; after each second switch K2 is closed, the voltage of the DC bus is converted into a power supply voltage to supply power to the secondary device 13 .

[0096] Since the power supply circuit 12 is connected to each first node A and the DC bus, the voltage of one of the first nodes A or the voltage of the DC bus is converted into a supply voltage to power the secondary device 13. That is, the power supply point of the secondary device 13 is placed at the positive and negative ends of the energy storage module 11 and the bus end of the DC bus, the AC power supply point of the mains is eliminated, and the traditional mains power supply architecture is abandoned. The power of the energy storage module 11 of the energy storage station itself is used to power the secondary device 13, which reduces the power supply cost. In addition, only the insulation and voltage resistance design needs to be done on the energy storage module 11, which reduces the difficulty of the insulation and voltage resistance design and improves safety and reliability.

[0097] According to some embodiments of this application, optionally, please continue to refer to Figure 2 , Figure 2 A schematic diagram of the structure of a DC power supply system provided by another embodiment of the present application is shown. For ease of explanation, only the parts related to this embodiment are shown, which are detailed as follows:

[0098] The above DC power supply system is Figure 1 In addition to all the components and assemblies of the DC power supply system shown, the system also includes an energy storage converter 14 .

[0099] The energy storage converter 14 is connected to the DC bus and is configured to convert AC power into input DC power and transmit the input DC power to the DC bus.

[0100] The power supply circuit 12 is specifically configured to convert the input direct current into a supply voltage to supply power to the secondary device 13 .

[0101] It should be noted that the energy storage converter 14 can be an AC / DC conversion circuit. A first end of the energy storage converter 14 is connected to the power grid, and a second end of the energy storage converter 14 is connected to the DC bus. This allows the DC power supply system to be connected to the power grid, enabling the AC power provided by the power grid to charge each energy storage module 1110 in the DC power supply system, or for each energy storage module 11 in the DC power supply system to discharge power to the power grid, thereby improving the practicality of the DC power supply system.

[0102] By adopting the above solution, it is achieved that when AC power is input from the grid side, power is generated through the AC side.

[0103] According to some embodiments of this application, optionally, please continue to refer to Figure 3 , Figure 3 A schematic diagram of the structure of a DC power supply system provided by another embodiment of the present application is shown. For ease of explanation, only the parts related to this embodiment are shown, which are detailed as follows:

[0104] The secondary device 13 includes a battery management system 131 .

[0105] The battery management system 131 is connected to the power supply circuit 12 and each second switch K2, and is configured to control each second switch K2 to be closed after being powered on by a power supply voltage.

[0106] When the AC side is powered, the second switch K2 is disconnected. At this time, the electric energy reaches the DC bus first, so priority is given to taking power from the DC bus and supplying power to the secondary device 13. After the battery management system 131 is powered on, it drives the second switch K2 to close. At this time, the energy storage module 11 on the DC side is connected to the AC side current, and the system then continues to operate normally.

[0107] By adopting the above solution, after the AC side is powered, each energy storage module 11 is connected to the DC bus, thereby connecting each energy storage module 11 to the power grid and operating normally.

[0108] According to some embodiments of this application, optionally, please continue to refer to Figure 3 The power supply circuit 12 is specifically configured to convert the voltage of the DC bus into a power supply voltage in response to the closing of each second switch K2 to supply power to the secondary device 13.

[0109] It is understandable that after the second switch K2 is driven to close, each energy storage module 11 self-discharges and achieves voltage balance. At this time, power is taken from the DC bus to power the secondary device 13, which is conducive to balanced discharge of each energy storage module 11.

[0110] By adopting the above solution, when each energy storage module 11 is connected to the power grid and operates normally, the DC power output by each energy storage module 11 is converged to the DC bus, and the DC bus is used as the power supply point for the secondary equipment 13, thereby improving the balanced control capability of each energy storage module 11.

[0111] According to some embodiments of this application, optionally, please continue to refer to Figure 4 , Figure 4 A schematic diagram of the structure of a DC power supply system provided by another embodiment of the present application is shown. For ease of explanation, only the parts related to this embodiment are shown, which are detailed as follows:

[0112] The power supply circuit 12 is specifically configured to convert the voltage of one of the first nodes A into a supply voltage in response to each second switch K2 being turned off, so as to power the secondary device 13 ; the secondary device 13 includes a battery management system 131 and an energy management system 132 .

[0113] The energy management system 132 is connected to the energy storage converter 14 and is configured to output a start signal in response to the shutdown and start instructions of the AC power.

[0114] The battery management system 131 is connected to the energy management system 132 , the power supply circuit 12 and each second switch K2 , and is configured to control each second switch K2 to be closed according to the start signal.

[0115] It should be noted that in the black start state, the DC bus is in a power-free state. The first node A has a high voltage due to the presence of the energy storage module 11, so power is taken from the first node A. When the battery management system 131 receives the start signal, the second switch K2 is closed to turn on the entire main circuit, thereby connecting each energy storage module 11 to the AC side to complete the black start.

[0116] By adopting the above solution, in the absence of AC power access, a black start of the DC power supply system is achieved by using one of the first nodes A as a power supply point for the secondary device 13. After the black start, the battery management system 131 and the energy management system 132 control the closure of each second switch K2, thereby connecting each energy storage module 11 to the power grid and operating normally.

[0117] According to some embodiments of this application, optionally, please continue to refer to Figure 4 The power supply circuit 12 is specifically configured to convert the voltage of the DC bus into a power supply voltage in response to the closing of each second switch K2 to supply power to the secondary device 13.

[0118] It is understandable that after the second switch K2 is driven to close, each energy storage module 11 self-discharges and achieves voltage balance. At this time, power is taken from the DC bus to power the secondary device 13, which is conducive to balanced discharge of each energy storage module 11.

[0119] By adopting the above solution, each energy storage module 11 is connected to the power grid. When the energy storage modules 11 are operating normally, the DC power output by each energy storage module 11 is converged to the DC bus, and the DC bus is used as the power supply point for the secondary equipment 13, thereby improving the balanced control capability of each energy storage module 11.

[0120] According to some embodiments of this application, optionally, please continue to refer to Figure 5 , Figure 5 A schematic diagram of the structure of a DC power supply system provided by another embodiment of the present application is shown. For ease of explanation, only the parts related to this embodiment are shown, which are detailed as follows:

[0121] The power supply circuit 12 includes a first power circuit 121 , a plurality of second power circuits 122 , and a power distribution circuit 123 .

[0122] The first power circuit 121 is connected to the DC bus and is configured to convert the voltage of the DC bus into a first voltage.

[0123] Each second power circuit 122 is connected to each first node A in a one-to-one correspondence, and is configured to convert the voltage of each first node A into a corresponding second voltage.

[0124] The distribution circuit 123 is connected to the first power circuit 121 and multiple second power circuits 122, and is configured to convert the first voltage into a power supply voltage in response to the difference between each second voltage minus the first voltage being less than or equal to the first preset voltage; and in response to the difference between the second voltage minus the first voltage being greater than the first preset voltage, convert the largest second voltage into a power supply voltage.

[0125] It should be noted that the DC power supply system has a DC bus terminal power point for current measurement and multiple power supply points for energy storage modules 11. Each of these converts the high voltage into the low voltage required by the secondary device 13 through the corresponding power circuit for power supply. A distribution circuit 123 is also provided between the power circuit and the secondary device 13. The distribution circuit 123 is used to follow the principle of "whoever has the highest voltage takes it" to take the DC power with the highest voltage on the input side and output a supply voltage. Its purpose is to take priority over the energy storage module 11 with high power at the input end to further optimize the balancing strategy. For example, the output voltage of the first power circuit 121 can be designed to be outputted in priority over the output voltage of the second power circuit 122. Therefore, when the second switch K2 is closed and the self-discharge of each energy storage module 11 reaches equilibrium, the output voltage of all power circuits will continue to be drawn from the DC bus after passing through the distribution module.

[0126] If the DC bus voltage is insufficient or unable to supply power for other reasons, each energy storage module 11 can adopt a "rotational power supply" strategy through the power distribution circuit 123. When the voltage of the current energy storage module 11 reaches a certain value, the other energy storage modules 11 will replace it according to the principle of "whoever has the higher voltage will take over", and so on. This ensures that the power consumption of all energy storage modules 11 is balanced, and prevents a single energy storage module 11 from continuously supplying power and causing the SOC to be too low. This method ensures voltage balance among the energy storage modules 11, solves the power supply problem of the off-ground energy storage system, and improves system utilization and overall reliability.

[0127] By adopting the above solution, power is taken from the DC bus first. When the voltage of the DC bus is insufficient, power is taken from the energy storage module 11 with the highest voltage, thereby achieving voltage balance among the energy storage modules 11 and improving system utilization and reliability.

[0128] According to some embodiments of this application, optionally, please continue to refer to Figure 5 , Figure 5 A schematic diagram of the structure of a DC power supply system provided by another embodiment of the present application is shown. For ease of explanation, only the parts related to this embodiment are shown, which are detailed as follows:

[0129] The secondary device 13 includes a battery management system 131 .

[0130] The battery management system 131 is connected to each energy storage module 11, each second power circuit 122 and the distribution circuit 123, and is configured to control the second power circuit 122 connected to the target energy storage module 11 to stop working, wherein the target energy storage module 11 is an energy storage module 11 with a power less than a preset value.

[0131] When one energy storage module 11 is low on power, the second power circuit 122 corresponding to the energy storage module 11 is put into hibernation, and the other energy storage modules 11 can adopt a "rotational power supply" strategy through the power distribution circuit 123, thereby ensuring the balance of power among the energy storage modules 11 and preventing over-discharge of the energy storage modules 11.

[0132] By adopting the above solution, when the power level of the energy storage module 11 is less than a preset value, the second power circuit 122 corresponding to the energy storage module 11 stops working, thereby preventing over-discharge of the energy storage module 11 and improving system reliability.

[0133] In some embodiments, optionally, please continue to refer to Figure 6 , the power distribution circuit 123 includes a first diode D1, a plurality of second diodes D2, and a plurality of third diodes D3.

[0134] The anode of the first diode D1 constitutes the first voltage input terminal of the distribution circuit 123, and is connected to the first power circuit 121 to access the first voltage; the anodes of each second diode D2 respectively constitute the second voltage input terminals of the distribution circuit 123, and are connected one-to-one with each second power circuit 122 to access each second voltage; the cathode of each second diode D2 is connected one-to-one with the anode of each third diode D3; the cathode of each third diode D3 is connected to the cathode of the first diode D1 and constitutes the power supply voltage output terminal of the distribution circuit 123, and is connected to the secondary device 13 to output the power supply voltage.

[0135] It can be understood that the first voltage is stepped down through the first diode D1 , and the second voltage is stepped down through the second diode D2 and the third diode D3 .

[0136] After each second switch K2 is closed and each energy storage module 11 self-discharges to reach voltage equilibrium, when the first voltage and the second voltage are equal, since the first voltage is only stepped down by one diode and the second voltage is stepped down by two diodes, each second diode D2 and each third diode D3 is cut off, and the branches of each second diode D2 and each third diode D3 are disconnected. The distribution circuit 123 draws power from the first voltage (the voltage of the DC bus), thereby converting the first voltage into a supply voltage in response to the difference between each second voltage and the first voltage being less than or equal to the first preset voltage (the voltage drop of one diode).

[0137] When the difference between the second voltage and the first voltage is greater than the first preset voltage (the voltage drop of a diode) (for example, when there is no AC power input and each second switch K2 is disconnected, there is no voltage on the DC bus), the first diode D1 is cut off, and the maximum second voltage is converted into a supply voltage, that is, power is taken from the energy storage module 11 corresponding to the maximum second voltage. After the energy storage module 11 discharges for a period of time, the voltage of the energy storage module 11 is lower than the voltage of the other energy storage module 11, so that the second voltage corresponding to the other energy storage module 11 is converted into a supply voltage through the second diode D2 and the third diode D3. This cycle is repeated to achieve balanced discharge of each energy storage module 11.

[0138] By adopting the above solution, power is taken from the DC bus first through the circuit topology. When the voltage of the DC bus is insufficient, power is taken from the energy storage module 11 with the highest voltage. This implementation method does not require software configuration, has high reliability and low cost.

[0139] In some embodiments, optionally, please continue to refer to Figure 7 The first power circuit 121 and the second power circuit 122 both include a power module, and the power module includes a third switch S3, a fourth diode D4, an inductor L, and a capacitor C.

[0140] The first end of the third switch S3 constitutes the voltage input end of the power module and is connected to the DC bus or the first node A to receive the voltage of the DC bus or the voltage of the first node A; the second end of the third switch S3 is connected to the cathode of the fourth diode D4 and the first end of the inductor L; the second end of the inductor L is connected to the first end of the capacitor C and constitutes the voltage output end of the power module, and the voltage output end of the power module is connected to the distribution circuit 123 to output the first voltage or the second voltage; the second end of the capacitor C and the anode of the fourth diode D4 are connected to the power ground.

[0141] It is understandable that the circuit of the power module is a step-down circuit, and the power module can also be implemented through other circuit topologies, which is not limited here.

[0142] In a specific implementation, the battery management system 131 controls the second power circuit 122 connected to the target energy storage module 11 to stop working. Specifically, the battery management system 131 controls the third switch S3 in the second power circuit 122 connected to the target energy storage module 11 to be disconnected.

[0143] By adopting the above solution, the power circuit is simple and reliable, and has a sleep and stop working function.

[0144] According to some embodiments of the present application, there is also provided a method for Figure 1 The control method of the DC power supply system shown includes:

[0145] Get the voltage of the DC bus;

[0146] When the voltage of the DC bus is greater than the second preset voltage, the voltage of the DC bus is converted into a supply voltage to supply power to the secondary device 13; the secondary device 13 includes a battery management system 131;

[0147] When the voltage of the DC bus is less than or equal to the second preset voltage, converting the voltage of one of the first nodes A into a power supply voltage to supply power to the secondary device 13;

[0148] After each second switch K2 is closed, the voltage of the DC bus is converted into a supply voltage to supply power to the secondary device 13 ; wherein each second switch K2 is controlled to be closed by the battery management system 131 after power-on.

[0149] It should be noted that when the AC side is powered, the second switch K2 is not closed. At this time, the electricity reaches the DC bus first (the voltage of the DC bus is greater than the second preset voltage), so priority is given to taking power from the DC bus. After the battery management system 131 is powered on, it drives the second switch K2 to close. At this time, the DC side battery is connected to the AC side current, and the system then continues to operate normally.

[0150] In the black start state, the DC bus is in a power-free state. Due to the presence of the energy storage module 11, each first node A has a high voltage, so power is taken from the first node A. Similarly, when the battery management system 131 is powered on, the second switch K2 is closed to turn on the entire main circuit, thereby driving the entire AC side, completing the black start, and the system then continues to operate normally.

[0151] When the system is in normal operation, since the first nodes A are distributed on each energy storage module 11, the length of the power-drawing time affects the inconsistency of the voltages of each energy storage module 11. Therefore, priority is given to using the DC bus on the bus side as the power-drawing point to protect the consistency of each energy storage module 11 and improve the reliability of the DC power supply system.

[0152] By adopting the above scheme, when the voltage of the DC bus is greater than the second preset voltage, power is taken through the DC bus; when the voltage of the DC bus is less than or equal to the second preset voltage, power is taken through one of the first nodes A, that is, power supply can be achieved in various scenarios during AC side power-up, black start and continuous operation.

[0153] According to some embodiments of the present application, optionally, as Figure 8 As shown, the power supply circuit 12 includes a first power circuit 121 , a plurality of second power circuits 122 and a power distribution circuit 123 .

[0154] The first power circuit 121 is connected to the DC bus and is configured to convert the voltage of the DC bus into a first voltage.

[0155] Each second power circuit 122 is connected to each first node A in a one-to-one correspondence, and is configured to convert the voltage of each first node A into a second voltage.

[0156] The power distribution circuit 123 is connected to the first power circuit 121 and the plurality of second power circuits 122 and is configured to convert the first voltage into a supply voltage in response to the difference between each second voltage minus the first voltage being less than or equal to the first preset voltage; and in response to the difference between the second voltage minus the first voltage being greater than the first preset voltage, convert the second voltage having the largest voltage value into the supply voltage;

[0157] The control method also includes:

[0158] Obtaining the power of each energy storage module 11;

[0159] Mark the energy storage module 11 whose power is less than the preset value as the target energy storage module 11;

[0160] The second power circuit 122 connected to the target energy storage module 11 is controlled to stop working.

[0161] When one energy storage module 11 is low on power, the second power circuit 122 corresponding to the energy storage module 11 is put into hibernation, and the other energy storage modules 11 can adopt a "rotational power supply" strategy through the power distribution circuit 123, thereby ensuring the balance of power among the energy storage modules 11 and preventing over-discharge of the energy storage modules 11.

[0162] By adopting the above solution, when the power level of the energy storage module 11 is less than a preset value, the second power circuit 122 corresponding to the energy storage module 11 stops working, thereby preventing over-discharge of the energy storage module 11 and improving system reliability.

[0163] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A DC power supply system, characterized in that: The DC power supply system includes multiple energy storage modules, multiple first switches, multiple second switches, a DC bus and a power supply circuit; Each of the energy storage modules is connected to the first end of each of the first switches in a one-to-one correspondence; The second end of each first switch is connected to the first end of each second switch via each first node in a one-to-one correspondence; The second end of each second switch is connected to the DC bus; The power supply circuit is connected to each of the first nodes and the DC bus, and is configured to convert the voltage of one of the first nodes or the voltage of the DC bus into a power supply voltage to power a secondary device.

2. The DC power supply system according to claim 1, wherein: The DC power supply system also includes: an energy storage converter connected to the DC bus and configured to convert AC power into input DC power and transmit the input DC power to the DC bus; The power supply circuit is specifically configured to convert the input direct current into the supply voltage to power the secondary device.

3. The DC power supply system according to claim 2, wherein: The secondary device includes a battery management system; The battery management system is connected to the power supply circuit and each of the second switches, and is configured to control each of the second switches to be closed after being powered on by the power supply voltage.

4. The DC power supply system according to claim 3, wherein: The power supply circuit is specifically configured to convert the voltage of the DC bus into a power supply voltage in response to each second switch being closed, so as to supply power to a secondary device.

5. The DC power supply system according to claim 2, wherein: The power supply circuit is specifically configured to convert the voltage of one of the first nodes into a power supply voltage in response to each of the second switches being turned off, so as to power a secondary device; The secondary equipment includes a battery management system and an energy management system; The energy management system is connected to the energy storage converter and is configured to output a start signal in response to the shutdown and start instructions of the alternating current; The battery management system is connected to the energy management system, the power supply circuit and each of the second switches, and is configured to control each of the second switches to be closed according to the start signal.

6. The DC power supply system according to claim 5, wherein: The power supply circuit is specifically configured to convert the voltage of the DC bus into a power supply voltage in response to each second switch being closed, so as to supply power to a secondary device.

7. The DC power supply system according to claim 1, wherein: The power supply circuit includes a first power circuit, a plurality of second power circuits and a power distribution circuit; The first power circuit is connected to the DC bus and configured to convert the voltage of the DC bus into a first voltage; Each of the second power circuits is connected to each of the first nodes in a one-to-one correspondence, and is configured to convert the voltage of each of the first nodes into a corresponding second voltage; a power distribution circuit connected to the first power circuit and a plurality of the second power circuits, and configured to convert the first voltage into the supply voltage in response to a difference between each of the second voltages and the first voltage being less than or equal to a first preset voltage; In response to the fact that the difference between the second voltage and the first voltage is greater than the first preset voltage, the second voltage with the largest voltage value is converted into the supply voltage.

8. The DC power supply system according to claim 7, wherein: The secondary device includes a battery management system; The battery management system is connected to each of the energy storage modules, each of the second power circuits, and the power distribution circuit, and is configured to control the second power circuit connected to a target energy storage module to stop working, wherein the target energy storage module is the energy storage module with a power level less than a preset value.

9. The DC power supply system according to claim 7, wherein: The power distribution circuit includes a first diode, a plurality of second diodes, and a plurality of third diodes; The anode of the first diode constitutes the first voltage input terminal of the power distribution circuit and is connected to the first power circuit to receive the first voltage; The anodes of the second diodes respectively constitute the second voltage input terminals of the power distribution circuit and are connected to the second power circuits in a one-to-one correspondence to access the second voltages. The cathode of each second diode is connected to the anode of each third diode in a one-to-one correspondence; The cathode of each of the third diodes is connected to the cathode of the first diode and constitutes a power supply voltage output end of the power distribution circuit. The power supply voltage output end is connected to the secondary device to output the power supply voltage.

10. The DC power supply system according to claim 7, wherein: The first power circuit and the second power circuit each include a power module, wherein the power module includes a third switch, a fourth diode, an inductor, and a capacitor; The first end of the third switch constitutes a voltage input end of the power module, and is connected to the DC bus or the first node to receive the voltage of the DC bus or the voltage of the first node; The second end of the third switch is connected to the cathode of the fourth diode and the first end of the inductor; The second end of the inductor and the first end of the capacitor are connected to form a voltage output end of the power module, and the voltage output end of the power module is connected to the power distribution circuit to output the first voltage or the second voltage; The second end of the capacitor and the anode of the fourth diode are connected to the power ground.

11. An energy storage station, characterized in that: The energy storage station includes the direct current power supply system according to any one of claims 1 to 10.

12. A control method applied to a DC power supply system according to any one of claims 1 to 10, characterized in that: include: Get the voltage of the DC bus; When the voltage of the DC bus is greater than a second preset voltage, converting the voltage of the DC bus into a supply voltage to supply power to a secondary device; the secondary device includes a battery management system; When the voltage of the DC bus is less than or equal to a second preset voltage, converting the voltage of one of the first nodes into a power supply voltage to supply power to the secondary device; When each of the second switches is closed, the voltage of the DC bus is converted into the supply voltage to supply power to the secondary device; wherein each of the second switches is controlled to be closed by the battery management system after power-on.

13. The control method according to claim 12, wherein: The power supply circuit includes a first power circuit, a plurality of second power circuits and a power distribution circuit; The first power circuit is connected to the DC bus and configured to convert the voltage of the DC bus into a first voltage; Each of the second power circuits is connected to each of the first nodes in a one-to-one correspondence, and is configured to convert the voltage of each of the first nodes into a second voltage; a power distribution circuit connected to the first power circuit and a plurality of the second power circuits, and configured to convert the first voltage into the supply voltage in response to a difference between each of the second voltages and the first voltage being less than or equal to a first preset voltage; In response to the difference between the second voltage and the first voltage being greater than the first preset voltage, converting the second voltage having the largest voltage value into the supply voltage; The control method further includes: Obtaining the power of each of the energy storage modules; Marking the energy storage module whose power is less than a preset value as a target energy storage module; The second power circuit connected to the target energy storage module is controlled to stop working.

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