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

Abstract

A direct current power supply system, a control method thereof and an energy storage station belong to the technical field of power electronics, comprising a plurality of energy storage modules, a plurality of first switches, a plurality of second switches, a direct current bus and a power supply circuit; each energy storage module is connected to the first end of each first switch in one-to-one correspondence; the second end of each first switch is connected to the first end of each second switch through each first node in one-to-one correspondence; 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 to supply power to secondary equipment; therefore, the direct current power supply system is provided to meet the power supply demand of the secondary equipment of the energy storage station, and the power supply cost is reduced, and the difficulty of insulation withstand voltage design is reduced.

Description

Technical Field

[0001] This application belongs to the field of power electronics technology, and in particular relates to a DC power supply system and its control method, and an energy storage station. Background Technology

[0002] The related secondary equipment power supply architecture mainly uses AC mains power as the power source and converts AC power to DC power required by the equipment or user-side equipment through power conversion modules. However, this scheme only provides an AC power supply architecture and does not consider valve tower energy storage systems (such as energy storage stations) as a power source to supply power to the high-voltage grid, rather than using AC mains power.

[0003] Secondary equipment in energy storage stations plays a crucial role in communication, monitoring, regulation, and safety protection. Therefore, the power supply for secondary equipment is the prerequisite and foundation for all these critical functions. Although traditional mains power supply has a simple and mature architecture, its application in some valve tower energy storage systems using high-voltage grid voltage leads to excessively high transformer hardware costs and significant challenges in designing the insulation withstand voltage on the high-voltage grid side. Thus, continuous power supply to secondary equipment becomes a primary concern.

[0004] Therefore, there is an urgent need to provide a DC power supply system to meet the power supply requirements of the secondary equipment in the energy storage station. Summary of the Invention

[0005] In view of the above problems, this 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 needs of the secondary equipment of the energy storage station through DC power supply.

[0006] In a first aspect, this application provides a DC power supply system, which includes multiple energy storage modules, multiple first switches, multiple second switches, a DC bus, and a power supply circuit.

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

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

[0009] The second terminal of each of the second switches 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 supply power to the secondary equipment.

[0011] In the technical solution of this application embodiment, 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 the power supply voltage to power the secondary equipment. That is, the power supply point of the secondary equipment is placed at the positive and negative terminals of the energy storage module and the confluence terminal of the DC bus, eliminating the AC mains power supply point and abandoning the traditional mains power supply architecture. 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. Moreover, only the insulation withstand voltage design of the energy storage module is required, which reduces the difficulty of the insulation withstand voltage design.

[0012] In some embodiments, the DC power supply system further includes;

[0013] An energy storage converter, connected to the DC bus, is 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 DC power into the supply voltage to power the secondary equipment.

[0015] By adopting the above scheme, it is possible to generate power through the AC side when AC power is input from the grid 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 the closing of each of the second switches after being powered on by the power supply voltage.

[0018] By adopting the above scheme, after the AC side is powered on, each energy storage module is connected to the DC bus, thus enabling each energy storage module to be connected to the power grid and operate normally.

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

[0020] By adopting the above scheme, when each energy storage module is connected to the power grid and is working normally, the DC power output by each energy storage module is fed into the DC bus, and the DC bus is used as the power source 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 the turning off of each of the second switches, so as to supply power to the 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 AC power cut-off and start commands.

[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 the closing of each of the second switches according to the start signal.

[0025] By adopting the above scheme, in the absence of AC power access, black start of the DC power supply system is achieved by using one of the first nodes as the power source for the secondary equipment. After black start, the battery management system and energy management system control the closing of each of the second switches, thereby connecting each energy storage module to the power grid and enabling it to operate normally.

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

[0027] By adopting the above scheme, each energy storage module is connected to the power grid and, under normal working conditions, the DC power output by each energy storage module is fed into the DC bus, and the DC bus is used as the power source 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 is 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 corresponding manner, and is configured to convert the voltage of each of the first nodes into the corresponding second voltage.

[0031] A power distribution circuit, connected to the first power circuit and a plurality of second power circuits, is configured to convert the first voltage into the supply voltage in response to the fact that the difference between each second voltage and the first voltage is less than or equal to a first preset voltage; and in response to the fact that the difference between each 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.

[0032] By adopting the above scheme, power is preferentially drawn from the DC bus. When the voltage of the DC bus is insufficient, power is drawn from the energy storage module with the highest voltage, thus 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 the target energy storage module to stop working, wherein the target energy storage module is the energy storage module whose power is less than a preset value.

[0035] By adopting the above scheme, when the energy storage module's charge 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 the system's 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 positive terminal of the first diode forms the first voltage input terminal of the power distribution circuit and is connected to the first power circuit to receive the first voltage.

[0038] Each of the second diodes is configured to serve as a second voltage input terminal of the power distribution circuit, and is connected to each of the second power circuits in a one-to-one correspondence to receive the second voltage.

[0039] The negative terminal of each second diode is connected to the positive terminal of each third diode in a one-to-one correspondence.

[0040] The negative terminals of each of the third diodes are connected to the negative terminals of the first diodes to form the power supply voltage output terminal of the power distribution circuit. The power supply voltage output terminal is connected to the secondary equipment to output the power supply voltage.

[0041] By adopting the above scheme, power is preferentially drawn from the DC bus through circuit topology. When the voltage of the DC bus is insufficient, power is drawn 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, both the first power circuit and the second power circuit 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 the voltage input terminal 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 terminal of the third switch is connected to the negative terminal of the fourth diode and the first terminal of the inductor;

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

[0046] The second terminal of the capacitor and the positive terminal of the fourth diode are both connected to the power supply ground.

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

[0048] This application also provides a control method for the above-mentioned DC power supply system, including:

[0049] Obtain the voltage of the DC bus;

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

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

[0052] When each of the second switches is closed, the voltage of the DC bus is converted into the supply voltage to power the secondary equipment; wherein each of the second switches is controlled to close 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 drawn through the DC bus; when the voltage of the DC bus is less than or equal to the second preset voltage, power is drawn through one of the first nodes. That is, power supply can be realized in various scenarios when the AC side is powered on, during black start, and during 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 is 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 the respective second voltage;

[0057] A power distribution circuit, connected to the first power circuit and a plurality of second power circuits, is configured to convert the first voltage into the supply voltage in response to the fact that the difference between each second voltage and the first voltage is less than or equal to a first preset voltage; and to convert the second voltage with the largest voltage value into the supply voltage in response to the fact that the difference between each second voltage and the first voltage is greater than the first preset voltage.

[0058] The control method further includes:

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

[0060] The energy storage module whose power is less than a preset value is marked as the 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 scheme, when the energy storage module's charge 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 the system's reliability.

[0063] Secondly, embodiments of the present invention also provide an energy storage station, the energy storage station including the aforementioned DC power supply system.

[0064] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0065] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

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

[0067] Figure 2 This is another schematic diagram of a DC power supply system provided in one embodiment of the present application;

[0068] Figure 3 This is another schematic diagram of a DC power supply system provided in one embodiment of the present application;

[0069] Figure 4This is another schematic diagram of a DC power supply system provided in one embodiment of the present application;

[0070] Figure 5 This is another schematic 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 this application;

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

[0073] Figure 8 This is a schematic diagram of another structure of a DC power supply system provided in one embodiment of this application. Detailed Implementation

[0074] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0075] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0076] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

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

[0078] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0079] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0080] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0081] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0082] Currently, judging from market trends, the application of energy storage power systems is becoming increasingly widespread. Energy storage power systems are widely used in the power transmission and distribution network sector. As the application areas of energy storage power systems continue to expand, the market demand for them is also constantly increasing.

[0083] With the widespread application of energy storage power systems in power transmission and distribution networks, solving the power supply problem for secondary equipment has become a current social issue. The safety and reliability of power supply for secondary equipment have attracted attention. The aforementioned energy storage power supply system includes a mains power network and N load power supply devices. Each load power supply device is connected to the mains power network via 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, receiving relevant power parameters from each load power supply device. Based on these parameters, the control module performs power regulation judgments and calculations. When the judgment and calculation results indicate that the load power supply device corresponding to the control module needs to allocate power to a load power supply device with insufficient power, the control module outputs power to the AC power supply network to supply power to the load power supply device with insufficient power. However, this energy storage power supply system requires a dedicated energy storage module and insulation withstand voltage design on the mains power network side, resulting in high power supply costs and significant challenges in insulation withstand voltage design.

[0084] To address the issues of high power supply costs and complex insulation withstand voltage design, research has found that the secondary equipment can be powered by the energy storage modules themselves. Power can be drawn from the positive and negative terminals of the energy storage modules and the DC bus junction to supply power to the secondary equipment, thereby reducing power supply costs and the complexity of insulation withstand voltage design.

[0085] According to some embodiments of this application, refer to Figure 1 , Figure 1 A schematic diagram of a DC power supply system according to an embodiment of this application is shown. For ease of explanation, only the parts relevant to this embodiment are shown, and are described in detail below:

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

[0087] Each energy storage module 11 is connected to the first terminal 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.

[0089] The second terminal 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 equipment 13.

[0091] It is understood that the energy storage module 11 includes a battery module, which internally contains battery cells and components such as copper busbars or wiring harnesses for high-voltage connection. The first switch K1 can be a manually controllable switching device. The second switch K2 can be a high-voltage contactor or a relay. The relay can be an electromagnetic relay, an inductive relay, an electric relay, an electronic relay, etc., and is not limited here. The high-voltage contactor can be an electromagnetic contactor, a permanent magnet contactor, etc., and is not limited here.

[0092] exist Figure 1 The working principle of the DC power supply system shown is as follows:

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

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

[0095] After the battery management system 131 is powered on, it controls each of the second switches K2 to close; after each of the second switches K2 is closed, the voltage of the DC bus is converted into the power supply voltage to supply power to the secondary equipment 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 the power supply voltage to power the secondary equipment 13. That is, the power supply point of the secondary equipment 13 is placed at the positive and negative terminals of the energy storage module 11 and the DC bus junction, eliminating the AC mains power supply point and abandoning the traditional mains power supply architecture. The power of the energy storage module 11 itself is used to power the secondary equipment 13, reducing the power supply cost. Moreover, only the insulation withstand voltage design of the energy storage module 11 is required, which reduces the difficulty of the insulation withstand voltage 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 a DC power supply system according to another embodiment of this application is shown. For ease of explanation, only the parts relevant to this embodiment are shown, and are described in detail below:

[0098] The above-mentioned DC power supply system, in addition to Figure 1 In addition to all the components and assemblies of the DC power supply system shown, it 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 DC power into the supply voltage to power the secondary device 13.

[0101] It should be noted that the energy storage converter 14 can be an AC-DC conversion circuit. The first terminal of the energy storage converter 14 is connected to the power grid, and the second terminal is connected to the DC bus. This allows the DC power supply system to be connected to the power grid, enabling the charging of each energy storage module 1110 in the DC power supply system using AC power supplied by the grid, or the discharging of each energy storage module 11 to the grid, thus improving the practicality of the DC power supply system.

[0102] By adopting the above scheme, it is possible to generate power through the AC side when AC power is input from the grid side.

[0103] According to some embodiments of this application, optionally, please continue to refer to Figure 3 , Figure 3 A schematic diagram of a DC power supply system according to another embodiment of this application is shown. For ease of explanation, only the parts relevant to this embodiment are shown, and are described in detail below:

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

[0105] The battery management system 131 is connected to the power supply circuit 12 and each of the second switches K2, and is configured to control each of the second switches K2 to close after the power supply voltage is applied.

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

[0107] By adopting the above scheme, after the AC side is powered on, each energy storage module 11 is connected to the DC bus, thus enabling each energy storage module 11 to be connected to the power grid and to operate 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 the power supply voltage in response to the closing of each second switch K2, so as to supply power to the secondary equipment 13.

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

[0110] By adopting the above scheme, when each energy storage module 11 is connected to the power grid and is working normally, the DC power output by each energy storage module 11 is fed into the DC bus, and the DC bus is used as the power source 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 a DC power supply system according to another embodiment of this application is shown. For ease of explanation, only the parts relevant to this embodiment are shown, and are described in detail below:

[0112] The power supply circuit 12 is specifically configured to convert the voltage of one of the first nodes A into a power supply voltage in response to the turn-off of each of the second switches K2, so as to supply power to 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 AC power off and start commands.

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

[0115] It should be noted that in the black start state, the DC bus is de-energized. The first node A has a high voltage due to the presence of the energy storage module 11, so power is drawn from the first node A. When the battery management system 131 receives the start signal, it will close the second switch K2 to conduct the entire main circuit, thereby connecting each energy storage module 11 to the AC side and completing the black start.

[0116] By adopting the above scheme, in the absence of AC power access, the black start of the DC power supply system is achieved by using one of the first nodes A as the power source for the secondary equipment 13. After the black start, the battery management system 131 and the energy management system 132 control the closing of each second switch K2, thereby connecting each energy storage module 11 to the power grid and enabling it to work 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 the power supply voltage in response to the closing of each second switch K2, so as to supply power to the secondary equipment 13.

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

[0119] By adopting the above scheme, each energy storage module 11 is connected to the power grid and, under normal working conditions, the DC power output by each energy storage module 11 is fed into the DC bus, and the DC bus is used as the power source 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 a DC power supply system according to another embodiment of this application is shown. For ease of explanation, only the parts relevant to this embodiment are shown, and are described in detail below:

[0121] The power supply circuit 12 includes a first power circuit 121, multiple 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 of the second power circuits 122 is connected to each of the first nodes A in a one-to-one correspondence, and is configured to convert the voltage of each of the first nodes A into the corresponding second voltage.

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

[0125] It should be noted that the DC power supply system has one DC bus terminal power take-off point and multiple energy storage module 11 terminal power take-off points. Each module, through its corresponding power circuit, converts the high voltage to the low voltage required by the secondary equipment 13 for power supply. A distribution circuit 123 is also provided between the power circuit and the secondary equipment 13. The distribution circuit 123 is used to take the highest DC voltage from the input side according to the principle of "whoever has the highest voltage takes the highest voltage" and output a single power supply voltage. Its purpose is to prioritize the energy storage module 11 with the highest input voltage, further optimizing the balancing strategy. For example, the output voltage of the first power circuit 121 can be designed to take precedence 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 is balanced, the output voltage of all power circuits, after passing through the distribution module, will always draw power from the DC bus.

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

[0127] By adopting the above scheme, power is preferentially drawn from the DC bus. When the voltage of the DC bus is insufficient, power is drawn from the energy storage module 11 with the highest voltage. This achieves voltage balance among the energy storage modules 11 and improves 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 a DC power supply system according to another embodiment of this application is shown. For ease of explanation, only the parts relevant to this embodiment are shown, and are described in detail below:

[0129] The secondary equipment 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 power 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 level less than a preset value.

[0131] When the power of one energy storage module 11 is insufficient, the second power circuit 122 corresponding to that energy storage module 11 will go into hibernation. Other energy storage modules 11 can adopt a "rotational power supply" strategy through the power distribution circuit 123 to ensure the power balance of the energy storage modules 11 and prevent the over-discharge of the energy storage modules 11.

[0132] By adopting the above scheme, when the energy storage module 11 has a power level lower than the preset value, the second power circuit 122 corresponding to the energy storage module 11 stops working, thereby preventing the energy storage module 11 from being over-discharged and improving the reliability of the system.

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

[0134] The anode of the first diode D1 forms the first voltage input terminal of the power distribution circuit 123 and is connected to the first power circuit 121 to receive the first voltage. The anodes of each second diode D2 form the second voltage input terminals of the power distribution circuit 123 and are connected to each second power circuit 122 to receive the second voltage. The cathodes of each second diode D2 are connected to the anodes of each third diode D3. The cathodes of each third diode D3 are connected to the cathodes of the first diode D1 and form the power supply voltage output terminal of the power distribution circuit 123, which is connected to the secondary device 13 to output the power supply voltage.

[0135] It is understandable that the first voltage is stepped down by the first diode D1, and the second voltage is stepped down by the second diode D2 and the third diode D3.

[0136] When each second switch K2 is closed and each energy storage module 11 self-discharges to achieve voltage balance, and the first voltage and the second voltage are equal, since the first voltage is stepped down by only one diode and the second voltage is stepped down by two diodes, each second diode D2 and each third diode D3 are cut off, and the branches of each second diode D2 and each third diode D3 are disconnected. The power distribution circuit 123 draws power from the first voltage (the voltage of the DC bus), thereby realizing the conversion of the first voltage into the supply voltage when the difference between each second voltage and the first voltage is 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 all second switches K2 are open, and there is no voltage on the DC bus), the first diode D1 is turned off, converting the maximum second voltage into the supply voltage. That is, power is drawn 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 another energy storage module 11. Thus, the second voltage corresponding to the other energy storage module 11 is stepped down by the second diode D2 and the third diode D3 and converted into the supply voltage. This cycle is repeated to achieve balanced discharge of each energy storage module 11.

[0138] By adopting the above scheme, power is preferentially drawn from the DC bus through circuit topology. When the voltage of the DC bus is insufficient, power is drawn 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 Both the first power circuit 121 and the second power circuit 122 include a power module, which includes a third switch S3, a fourth diode D4, an inductor L, and a capacitor C.

[0140] The first terminal of the third switch S3 forms the voltage input terminal 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 terminal of the third switch S3 is connected to the negative terminal of the fourth diode D4 and the first terminal of the inductor L; the second terminal of the inductor L and the first terminal of the capacitor C are connected to form the voltage output terminal of the power module, and the voltage output terminal of the power module is connected to the power distribution circuit 123 to output the first voltage or the second voltage; the second terminal of the capacitor C and the positive terminal of the fourth diode D4 are connected to the power supply ground.

[0141] It is understood that the circuit of this power module is a step-down circuit, but other circuit topologies can also be used to implement the power module, 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 open.

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

[0144] According to some embodiments of this application, a method for applying based on Figure 1 The control method for the DC power supply system shown includes:

[0145] Obtain 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 power supply voltage to supply power to the secondary equipment 13; the secondary equipment 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, the voltage of one of the first nodes A is converted into the power supply voltage to supply power to the secondary equipment 13;

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

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

[0150] In the black start state, the DC bus is de-energized. Each first node A has a high voltage due to the presence of the energy storage module 11, so power is drawn from the first node A. Similarly, when the battery management system 131 is powered on, it will close the second switch K2 to conduct the entire main circuit, thereby driving the entire AC side to complete the black start. The system then continues to operate normally.

[0151] When the system is in normal operation, since each first node A is distributed on each energy storage module 11, the duration of power extraction affects the voltage inconsistency of each energy storage module 11. Therefore, the DC bus on the combiner side is preferred as the power extraction 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 drawn through the DC bus; when the voltage of the DC bus is less than or equal to the second preset voltage, power is drawn through one of the first nodes A. That is, power supply can be realized in various scenarios when the AC side is powered on, during black start, and during continuous operation.

[0153] According to some embodiments of this application, optionally, such as Figure 8 As shown, the power supply circuit 12 includes a first power circuit 121, multiple 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 of the second power circuits 122 is connected to each of the first nodes A in a one-to-one correspondence, and is configured to convert the voltage of each of the first nodes A into the respective second voltage.

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

[0157] Control methods also include:

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

[0159] Energy storage module 11 with a power level less than a preset value is marked as target energy storage module 11;

[0160] The second power circuit 122, which is connected to the target energy storage module 11, stops working.

[0161] When the power of one energy storage module 11 is insufficient, the second power circuit 122 corresponding to that energy storage module 11 will go into hibernation. Other energy storage modules 11 can adopt a "rotational power supply" strategy through the power distribution circuit 123 to ensure the power balance of the energy storage modules 11 and prevent the over-discharge of the energy storage modules 11.

[0162] By adopting the above scheme, when the energy storage module 11 has a power level lower than the preset value, the second power circuit 122 corresponding to the energy storage module 11 stops working, thereby preventing the energy storage module 11 from being over-discharged and improving the reliability of the system.

[0163] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling 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 terminal of each of the first switches in a one-to-one correspondence. The second end of each of the first switches is connected to the first end of each of the second switches in a one-to-one correspondence via each of the first nodes; The second terminal of each of the second switches 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 the secondary equipment. The power supply circuit includes a first power circuit, multiple second power circuits, and a power distribution circuit. The first power circuit is connected to the DC bus and is 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 corresponding manner, and is configured to convert the voltage of each of the first nodes into the corresponding second voltage. A power distribution circuit, connected to the first power circuit and a plurality of second power circuits, is configured to convert the first voltage into the supply voltage in response to each second voltage minus the first voltage being less than or equal to a first preset voltage; Furthermore, in response to the existence of a difference between the second voltage and the first voltage that is greater than the first preset voltage, the second voltage with the largest voltage value is converted into the power supply voltage.

2. The DC power supply system as described in claim 1, characterized in that, The DC power supply system also includes; An energy storage converter, connected to the DC bus, is 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 DC power into the supply voltage to power the secondary equipment.

3. The DC power supply system as described in claim 2, characterized in that, The secondary equipment 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 the closing of each of the second switches after being powered on by the power supply voltage.

4. The DC power supply system as described in claim 3, characterized in that, The power supply circuit is specifically configured to convert the voltage of the DC bus into a power supply voltage in response to the closing of each of the second switches, so as to supply power to the secondary equipment.

5. The DC power supply system as described in claim 2, characterized in that, 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 the turning off of each of the second switches, so as to supply power to the secondary equipment. 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 commands of the AC power. 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 the closing of each of the second switches according to the start signal.

6. The DC power supply system as described in claim 5, characterized in that, The power supply circuit is specifically configured to convert the voltage of the DC bus into a power supply voltage in response to the closing of each of the second switches, so as to supply power to the secondary equipment.

7. The DC power supply system as described in claim 1, characterized in that, The secondary equipment 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 the target energy storage module to stop working, wherein the target energy storage module is the energy storage module whose power is less than a preset value.

8. The DC power supply system as described in claim 1, characterized in that, The power distribution circuit includes a first diode, multiple second diodes, and multiple third diodes; The positive terminal of the first diode forms the first voltage input terminal of the power distribution circuit and is connected to the first power circuit to receive the first voltage. The positive terminals of each second diode constitute the respective second voltage input terminals of the power distribution circuit, and are connected one-to-one with each of the second power circuits to access the respective second voltages; The negative terminal of each second diode is connected to the positive terminal of each third diode in a one-to-one correspondence. The negative terminals of each of the third diodes are connected to the negative terminals of the first diodes to form the power supply voltage output terminal of the power distribution circuit. The power supply voltage output terminal is connected to the secondary equipment to output the power supply voltage.

9. The DC power supply system as described in claim 1, characterized in that, Both the first power circuit and the second power circuit include a power module, and the power module includes a third switch, a fourth diode, an inductor, and a capacitor; The first end of the third switch constitutes the voltage input terminal 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 terminal of the third switch is connected to the negative terminal of the fourth diode and the first terminal of the inductor; The second end of the inductor and the first end of the capacitor are connected to form the voltage output terminal of the power module. The voltage output terminal of the power module is connected to the power distribution circuit to output the first voltage or the second voltage. The second terminal of the capacitor and the positive terminal of the fourth diode are connected to the power supply ground.

10. An energy storage station, characterized in that, The energy storage station includes a DC power supply system as described in any one of claims 1 to 9.

11. A control method applied to a DC power supply system as described in any one of claims 1 to 9, characterized in that, include: Obtain the voltage of the DC bus; When the voltage of the DC bus is greater than the second preset voltage, the voltage of the DC bus is converted into a power supply voltage to supply power to the secondary equipment; the secondary equipment includes a battery management system. When the voltage of the DC bus is less than or equal to the second preset voltage, the voltage of one of the first nodes is converted into a power supply voltage to supply power to the secondary equipment; When each of the second switches is closed, the voltage of the DC bus is converted into the supply voltage to power the secondary equipment; wherein each of the second switches is controlled to close by the battery management system after power-on.

12. The control method as described in claim 11, characterized in that, The power supply circuit includes a first power circuit, multiple second power circuits, and a power distribution circuit. The first power circuit is connected to the DC bus and is 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 the respective second voltage; A power distribution circuit, connected to the first power circuit and a plurality of second power circuits, is configured to convert the first voltage into the supply voltage in response to each second voltage minus the first voltage being less than or equal to a first preset voltage; Furthermore, in response to the existence of a difference between the second voltage and the first voltage that is greater than the first preset voltage, the second voltage with the largest voltage value is converted into the supply voltage; The control method further includes: Obtain the power of each of the energy storage modules; The energy storage module whose power is less than a preset value is marked as the target energy storage module; The second power circuit connected to the target energy storage module is controlled to stop working.

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