Power supply system

Abstract

The embodiment of the application provides a power supply system, which comprises an energy storage unit, a plurality of converters, a controller, a plurality of positive switch units and a plurality of negative switch units. The positive and negative DC terminals of the converters are connected with the positive and negative DC buses through the positive and negative switch units respectively, and the positive and negative DC buses are connected with the positive and negative poles of the energy storage unit respectively. The positive and negative DC terminals of the first converter are connected with the positive and negative DC buses through the first positive and negative switch units, and the positive and negative DC terminals of the second converter are connected with the positive and negative DC buses through the second positive and negative switch units. When the first converter is short-circuited, the controller controls the switch devices in the first positive and negative switch units to be disconnected, and controls the switch devices in the second positive and / or negative switch unit to be disconnected.

Description

Technical Field

[0001] This application relates to the field of power electronics, and more particularly to a power supply system. Background Technology

[0002] Energy storage systems are widely used in various scenarios, including industrial and commercial applications, power plants, residential applications, and charging stations. The energy storage converters in these systems primarily convert DC to AC power and control the charging and discharging processes of batteries, interacting with the power grid. In an energy storage system, a battery container needs to be equipped with multiple energy storage converters to simultaneously convert power. These converters are typically integrated inside the container or placed outside. For the entire energy storage system, when an energy storage converter fails, it can be actively disconnected to prevent the fault from spreading to the battery side and other devices connected in parallel with the failed converter. In the common DC / AC connection architecture of energy storage converters used to increase the capacity of the energy storage system, when one energy storage converter fails, there are not only short-circuit current paths between the battery system and the failed converter, and between the grid and the failed converter, but also a short-circuit current path between the grid and the faulty converter, posing a risk of damage to the battery side and devices connected in parallel with the failed converter. Therefore, how to prevent short-circuit faults in energy storage converters from spreading and affecting the normal operation of other equipment in energy storage systems with multiple energy storage converters is one of the urgent technical problems to be solved. Summary of the Invention

[0003] This application provides a power supply system that can cut off the short-circuit current between the converter and the corresponding energy storage unit, and prevent the short-circuit current from spreading and interfering with the normal operation of other converters or even damaging the converter.

[0004] In a first aspect, this application provides a power supply system comprising an energy storage unit, multiple converters, a controller, multiple positive switching units corresponding one-to-one with the multiple converters, and multiple negative switching units. The positive DC terminal of each converter is connected to a positive DC bus via a corresponding positive switching unit, and the negative DC terminal of each converter is connected to a negative DC bus via a corresponding negative switching unit. The positive and negative DC buses are respectively connected to the positive and negative terminals of the energy storage unit. The positive DC terminal of a first converter is connected to the positive DC bus via a first positive switching unit among the multiple positive switching units, and the negative DC terminal of the first converter is connected to the negative DC bus via a first negative switching unit among the multiple negative switching units. The positive DC terminal of a second converter is connected to the positive DC bus via a second positive switching unit among the multiple positive switching units, and the negative DC terminal of the second converter is connected to the negative DC bus via a second negative switching unit among the multiple negative switching units. The controller is used to, when the first converter is short-circuited, control the switching devices in the first positive switch unit and the first negative switch unit connected to the first converter to disconnect, and control the switching devices in the second positive switch unit and / or the second negative switch unit connected to the second converter to disconnect.

[0005] In this application, each converter in the power supply system controls the switching devices in the positive and negative switching units connected to that converter to turn off when any converter is short-circuited, either through its own controller or through a single controller, thereby cutting off the short-circuit current between the converter and the corresponding energy storage unit. Furthermore, the controller controls the switching devices in at least one of the positive and negative switching units connected to other converters in parallel with the faulty converter to turn off, thereby cutting off the short-circuit current path between the power grid, the diffusion equipment, and the faulty converter. This prevents short-circuit current from interfering with the normal operation of the converter or even damaging it, thus improving the reliability of the power supply system.

[0006] In one possible implementation, the controller is used to, when the first converter is short-circuited, control the switching devices in the first positive and first negative switching units connected to the first converter to disconnect, and control the switching devices in the second positive and / or second negative switching units connected to the second converter to disconnect. This includes controlling the switching devices in the first positive and first negative switching units connected to the first converter to disconnect when the voltage between the positive and negative DC buses connected to the first converter is less than a set voltage threshold, and controlling the switching devices in the second positive and / or second negative switching units connected to the second converter to disconnect. Here, the controller acquires the voltage between the positive and negative DC buses connected to each converter to detect whether a short-circuit fault has occurred in each converter, and controls the switching devices in the positive and negative switching units connected to that converter to turn off when the voltage between the positive and negative DC buses connected to any converter is too low, thereby cutting off the short-circuit current between the faulty converter and the corresponding energy storage unit. In addition, the controller controls the switching devices of at least one of the positive and negative switching units connected to the converter that has not experienced a short-circuit fault to turn off, thereby cutting off the short-circuit current path between the power grid, the diffuser, and the faulty converter, preventing short-circuit current from interfering with the normal operation of the converter or even damaging the converter, and improving the reliability of the power supply system.

[0007] In one possible implementation, the positive and / or negative switching units include anti-reverse devices, which are used to cut off short-circuit current when the switching device in the corresponding positive or negative switching unit is open. When a short-circuit fault occurs in the converter, the controller controls the switching devices in the positive and negative switching units connected to that converter to turn off, thereby cutting off the short-circuit current between the faulty converter and the corresponding energy storage unit. The controller also controls the switching devices in at least one of the positive and negative switching units connected to other converters to turn off when a short-circuit fault propagates, thereby cutting off the short-circuit current path flowing between the grid, the propagation equipment, and the faulty converter.

[0008] In one possible implementation, the negative switching unit includes a reverse protection device, and the switching device in the positive switching unit is used to connect or disconnect the connection between the positive DC bus and the positive DC terminal of the first converter, respectively, when the positive switch is turned on or off. The reverse protection device in the first negative switching unit is used to cut off the short-circuit current flowing from the negative DC terminal of the first converter to the negative terminal of the energy storage unit when the switching device in the first negative switching unit is turned off. The reverse protection device in the second negative switching unit is used to cut off the short-circuit current flowing from the negative DC terminal of the second converter to the negative DC terminal of the first converter when the switching device in the second negative switching unit is turned off. Here, the switching devices in each negative switching unit can be semiconductor switches, which can achieve microsecond-level turn-off, that is, can ensure the speed of cutting off short-circuit current and prevent the faulty converter from being damaged by overcurrent. The switching devices in each positive switching unit are fast turn-off devices. When each converter is operating normally, the fast turn-off device can reduce the loss of normal power current and ensure the power supply efficiency of the power supply system.

[0009] In one possible implementation, the positive and negative switching units include reverse protection devices. The reverse protection device in the first negative switching unit is used to cut off the short-circuit current flowing from the negative DC terminal of the first converter to the negative terminal of the energy storage unit when the switching device in the first negative switching unit is open. The reverse protection device in the second positive switching unit is used to cut off the short-circuit current flowing from the positive DC terminal of the second converter to the positive DC terminal of the first converter when the switching device in the second positive switching unit is open. The reverse protection device in the second negative switching unit is used to cut off the short-circuit current flowing from the negative DC terminal of the second converter to the negative DC terminal of the first converter when the switching device in the corresponding negative switching unit is open. When a short-circuit fault occurs in the converter, the controller controls the switching devices in the positive and negative switching units connected to that converter to turn off, thereby cutting off the short-circuit current between the faulty converter and the corresponding energy storage unit. The controller also controls the switching devices of at least one of the positive and negative switching units connected to other converters to turn off when a short-circuit fault propagates, thereby cutting off the short-circuit current path between the grid, the propagating machine, and the faulty converter.

[0010] In one possible implementation, the positive and negative switching units include reverse protection devices. The reverse protection device in the first positive switching unit is used to block the short-circuit current flowing from the positive terminal of the energy storage unit to the positive DC terminal of the first converter, and to block the short-circuit current flowing from the positive DC terminal of the second converter to the positive DC terminal of the first converter, when the switching device in the first positive switching unit is open. The reverse protection device in the first negative switching unit is used to block the short-circuit current flowing from the negative DC terminal of the first converter to the negative terminal of the energy storage unit, when the switching device in the first negative switching unit is open. The reverse protection device in the second negative switching unit is used to block the short-circuit current flowing from the negative DC terminal of the second converter to the negative DC terminal of the first converter, when the switching device in the second negative switching unit is open. When a short-circuit fault occurs in the converter, the controller controls the switching devices in the positive and negative switching units connected to the converter to turn off, thereby blocking the short-circuit current between the faulty converter and the corresponding energy storage unit. The controller also controls the switching devices of at least one of the positive and negative switching units connected to other converters to turn off when a short-circuit fault propagates, thereby cutting off the short-circuit current path between the grid, the propagating machine, and the faulty converter.

[0011] In one possible implementation, the energy storage unit and multiple converters are installed inside the container, and the AC terminals of the multiple converters are connected to the power grid through interfaces on the container.

[0012] Secondly, this application provides a power supply system, which includes an energy storage unit, multiple converters, a controller, multiple positive switching units and multiple negative switching units corresponding to the multiple converters. The positive DC terminal of each converter is connected to a positive DC bus through a corresponding positive switching unit, and the negative DC terminal of each converter is connected to a negative DC bus through a corresponding negative switching unit. The positive and negative DC buses are respectively connected to the positive and negative terminals of the energy storage unit. The positive DC terminal of the first converter among the multiple converters is connected to the positive DC bus through a first positive switching unit among the multiple positive switching units, and the negative DC terminal of the first converter is connected to the negative DC bus through a first negative switching unit among the multiple negative switching units. The positive DC terminal of the second converter among the multiple converters is connected to the positive DC bus through a second positive switching unit among the multiple positive switching units, and the negative DC terminal of the second converter is connected to the negative DC bus through a second negative switching unit among the multiple negative switching units. The switching devices in the first positive switching unit are used to cut off the current flowing into the positive DC terminal of the first converter when open. The switching devices in the first negative switching unit are used to cut off the current flowing into the negative DC terminal of the first converter or to cut off the current flowing out of the negative DC terminal of the first converter when open. The controller is used to control the switching devices in the first positive switching unit and the first negative switching unit connected to the first converter to disconnect when the first converter is short-circuited.

[0013] In this application, when a short-circuit fault occurs in the first converter, the controller controls the switching devices in the first positive switch unit and the first negative switch unit connected to the first converter to turn off. Since the switching devices in the first positive switch unit cut off the current flowing into the positive DC terminal of the first converter when they are disconnected, and the switching devices in the first negative switch unit cut off the current flowing into or out of the negative DC terminal of the first converter when they are disconnected, the short-circuit current between the faulty converter and the corresponding energy storage unit, as well as the short-circuit current flowing between the power grid, the diffusion machine, and the faulty converter, can be simultaneously cut off when the switching devices in the first positive and first negative switch units are disconnected. This prevents the short-circuit current from spreading and interfering with the normal operation of the converter or even damaging the converter, thus improving the reliability of the power supply system.

[0014] In one possible implementation, the positive and negative switching units include reverse protection devices. The reverse protection device in the first positive switching unit is used to block short-circuit current flowing from the positive terminal of the energy storage unit to the positive DC terminal of the first converter, and to block short-circuit current flowing from the positive DC terminal of the second converter to the positive DC terminal of the first converter, when the switching device in the first positive switching unit is open. The reverse protection device in the first negative switching unit is used to block short-circuit current flowing from the negative terminal of the energy storage unit to the negative DC terminal of the first converter, and to block short-circuit current flowing from the negative DC terminal of the second converter to the negative DC terminal of the first converter, when the switching device in the first negative switching unit is open. When a short-circuit fault occurs in the converter, the controller controls the switching devices in the positive and negative switching units connected to the converter to turn off, cutting off the short-circuit current between the faulty converter and the corresponding energy storage unit. At the same time, it can also cut off the short-circuit current path flowing between the power grid, the diffusion machine and the faulty converter. The operation is simple and prevents the short-circuit current from interfering with the normal operation of the converter or even damaging the converter.

[0015] In one possible implementation, the positive switching unit includes a reverse protection device, and the switching device in the negative switching unit is used to connect or disconnect the connection between the negative DC bus and the negative DC terminal of the first converter, respectively, when the switch in the first positive switching unit is turned off. The reverse protection device in the first positive switching unit is used to cut off the short-circuit current flowing from the positive terminal of the energy storage unit to the positive DC terminal of the first converter, and to cut off the short-circuit current flowing from the positive DC terminal of the second converter to the positive DC terminal of the first converter, when the switch in the first positive switching unit is turned off. When a short-circuit fault occurs in the converter, the controller controls the switching devices in the positive and negative switching units connected to the converter to turn off, cutting off the short-circuit current between the faulty converter and the corresponding energy storage unit. At the same time, it can also cut off the short-circuit current path flowing between the power grid, the diffusion machine, and the faulty converter. The operation is simple and prevents the short-circuit current from interfering with the normal operation of the converter or even damaging the converter. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of an application scenario of the power supply system provided in this application;

[0017] Figure 2 This is a schematic diagram of another application scenario of the power supply system provided in this application;

[0018] Figure 3 This is a structural schematic diagram of the power supply system provided in this application;

[0019] Figure 4 This is another structural schematic diagram of the power supply system provided in this application;

[0020] Figure 5This is another structural schematic diagram of the power supply system provided in this application;

[0021] Figure 6 This is another structural schematic diagram of the power supply system provided in this application;

[0022] Figure 7 This is another structural schematic diagram of the power supply system provided in this application;

[0023] Figure 8 This is another structural schematic diagram of the power supply system provided in this application;

[0024] Figure 9 This is another structural schematic diagram of the power supply system provided in this application;

[0025] Figure 10 This is another structural schematic diagram of the power supply system provided in this application. Detailed Implementation

[0026] See Figure 1 , Figure 1 This is a schematic diagram of an application scenario for the power supply system provided in this application. The power supply system provided in this application may include an energy storage unit and multiple converters. The positive DC terminal and negative DC terminal of each converter are connected to the positive and negative terminals of the energy storage unit via positive and negative DC busbars, respectively. The AC terminal of each converter is connected to the power grid, and each energy storage unit is connected to multiple converters. The converters can invert and convert the DC power provided by the energy storage unit to AC power and output it to the power grid. Furthermore, when the converters are connected to the grid, they can also rectify the AC power provided by the grid and output it to the corresponding energy storage unit for charging.

[0027] In some feasible implementations, the power supply system may include a transformer; see [link to relevant documentation]. Figure 2 , Figure 2 This is a schematic diagram of another application scenario of the power supply system provided in this application. The output terminals of each converter can be connected to the power grid through a transformer. The transformer can change (either step up or step down) the AC power provided by the converter and supply the transformed AC power to the power grid.

[0028] In some feasible implementations, the above Figure 1 or Figure 2 In the power supply system shown, the energy storage unit and multiple converters can be installed inside the container, and the AC terminals of the multiple converters are connected to the power grid through interfaces on the container.

[0029] exist Figure 1 or Figure 2In the power supply system application scenario shown, the converters connected to each energy storage unit are connected in a common DC-AC configuration. In other words, among the multiple converters connected to one energy storage unit, one end of each converter is connected to the same energy storage unit, and the other end of the converter is connected to the same power grid. When one of the energy storage converters in the power supply system fails, there is a short-circuit current path not only between the energy storage unit and the failed converter, but also between the power grid, the diffusion mechanism, and the failed converter. The diffusion mechanism refers to the other converters connected in parallel with the failed converter. Therefore, when one of the energy storage converters in the power supply system fails, the diffusion of the short-circuit current may simultaneously affect the energy storage unit and other converters connected in parallel. If the diffusion of the short-circuit fault is not prevented in time, it will further interfere with the normal operation of other converters in the power supply system and may even pose a risk of damage.

[0030] The power supply system provided in this application includes an energy storage unit, multiple converters, a controller, multiple positive switching units corresponding to each converter, and multiple negative switching units. The positive DC terminal of each converter is connected to a positive DC bus via a corresponding positive switching unit, and the negative DC terminal of each converter is connected to a negative DC bus via a corresponding negative switching unit. The positive and negative DC buses are respectively connected to the positive and negative terminals of the energy storage unit. The AC terminals of each converter are connected to the power grid. Here, the converter can be an independent power conversion device or a power conversion unit within a power conversion device. When the converter is an independent power conversion device, the positive and negative switching units are connected to the converter externally. When the converter is a power conversion unit, the positive and negative switching units are connected to the converter within the power conversion device. The aforementioned controller can be a controller located within multiple converters, with each converter controlling the corresponding switching unit connected to it. Alternatively, the controller can be located outside the converters, controlling the switching units connected to each converter. The specific controller choice depends on the actual application scenario and is not limited here. When a short-circuit fault occurs in one of the multiple converters (which can be referred to as the first converter), a short-circuit current appears in the power supply system. This short-circuit current includes a first short-circuit current and a second short-circuit current. Specifically, the first short-circuit current includes the short-circuit current flowing from the positive terminal of the energy storage unit to the positive DC terminal of the first converter, and the short-circuit current flowing from the negative DC terminal of the first converter to the negative terminal of the energy storage unit. The second short-circuit current includes the short-circuit current flowing from other converters (which can be referred to as the second converters) connected in parallel with the first converter to the first converter. The controller is used to turn off the switching devices in the first positive and first negative switching units connected to the first converter when the first converter is short-circuited. For example, the controller controls the switching devices in the first positive and first negative switching units to turn off, thereby cutting off the first short-circuit current, or simultaneously cutting off the first and second short-circuit currents. The controller is also used to control the switching devices in the second positive or second negative switching unit connected to the second converter to turn off, or to control the switching devices in the second positive and second negative switching units to turn off simultaneously, to cut off the second short-circuit current. Here, each converter, through its own controller, or through a single controller, controls the switching devices in the positive and negative switching units connected to that converter to turn off when any converter is short-circuited, thereby cutting off the short-circuit current between the converter and the corresponding energy storage unit.In addition, the controller controls the switching devices of at least one of the positive and negative switching units of other converters connected in parallel with the faulty converter to turn off, thereby cutting off the short-circuit current path between the power grid, the diffuser, and the faulty converter, preventing short-circuit current from interfering with the normal operation of the converter or even damaging the converter, and improving the reliability of the power supply system.

[0031] In some feasible implementations, the controller is configured to determine that a short-circuit fault has occurred in the first converter when the voltage between the positive and negative DC buses connected to the first converter is less than a set voltage threshold. When a short-circuit fault occurs in the first converter, a first short-circuit current and a second short-circuit current appear in the power supply system. Then, the controller controls the switching devices in the first positive and first negative switching units connected to the first converter to turn off. For example, the controller controls the switching devices in the first positive and first negative switching units to turn off, thereby cutting off the first short-circuit current, or simultaneously cutting off both the first and second short-circuit currents. The controller is also configured to determine that the magnitude of the second short-circuit current output by the second converter is greater than a set current threshold, for example, by detecting the common-mode current output by the second converter to obtain the magnitude of the second short-circuit current between the first converter and the parallel-connected second converter. When the magnitude of the second short-circuit current output by the second converter exceeds a set current threshold, the controller controls the switching devices in the second positive or second negative switching unit connected to the second converter to turn off, or controls the switching devices in both the second positive and second negative switching units to turn off simultaneously, in order to cut off the second short-circuit current. Here, each converter obtains the voltage between the positive and negative DC buses connected to each converter through its own controller, or through a single controller, to detect whether a short-circuit fault has occurred in each converter. When the voltage between the positive and negative DC buses connected to any converter is too low, the controller controls the switching devices in the positive and negative switching units connected to that converter to turn off, thereby cutting off the short-circuit current between the faulty converter and the corresponding energy storage unit. In addition, when the second short-circuit current output by the converter is too high, the controller determines that a short-circuit fault has spread and controls at least one of the switching devices in the positive and negative switching units connected to the converter to turn off, thereby cutting off the short-circuit current path between the power grid, the spreading machine and the faulty converter, preventing the short-circuit current from interfering with the normal operation of the converter or even damaging the converter, thus improving the reliability of the power supply system.

[0032] In some feasible implementations, the energy storage unit in the above-described power supply system is a battery cluster. See also Figure 3 , Figure 3 This is a structural schematic diagram of the power supply system provided in this application. Figure 3The power supply system shown includes an energy storage unit and multiple converters. The energy storage unit is a battery cluster comprising multiple battery packs connected in series. The energy storage unit is connected to multiple converters; taking two converters as an example... Figure 3 The system includes converter A and converter B. The positive and negative DC terminals of converter A are connected to the positive and negative terminals of the energy storage unit via positive and negative DC buses, respectively. A positive switch unit K11 and a negative switch unit K12 are connected in series on the positive and negative DC buses of converter A, respectively. Similarly, the positive and negative DC terminals of converter B are connected to the positive and negative terminals of the energy storage unit via positive and negative DC buses, respectively. A positive switch unit K21 and a negative switch unit K22 are connected in series on the positive and negative DC buses of converter B, respectively. Furthermore, the AC terminals of both converter A and converter B are connected to the power grid, and the AC terminals of both converter A and converter B can include three-phase output. Figure 3 In the power supply system shown, the controller ( Figure 3(Not shown) The controller acquires the voltage between the positive and negative DC buses connected to each converter, and determines that a short-circuit fault has occurred in the converter when the voltage between the positive and negative DC buses connected to any converter is less than a set voltage threshold. For example, the controller acquires the voltage between the positive and negative DC buses connected to converter A, and if this voltage is lower than a set voltage threshold, it determines that converter A has a short-circuit fault. When converter A experiences a short-circuit fault, a first short-circuit current Ia appears in the power supply system. The first short-circuit current Ia may include the short-circuit current flowing from the positive terminal of the energy storage unit to the positive DC terminal of the first converter, and the short-circuit current flowing from the negative DC terminal of the first converter to the negative terminal of the energy storage unit. When a short-circuit fault occurs in converter A, since converter B is connected in parallel with converter A, a second short-circuit current Ib1 and a second short-circuit current Ib2 also appear in the power supply system. The second short-circuit current Ib1 flows from the positive DC terminal of converter B to the positive DC terminal of converter A, and the second short-circuit current Ib2 flows from the negative DC terminal of converter B to the negative DC terminal of converter A. Then, the controller controls the switching devices in the positive switching unit K11 and the negative switching unit K12 connected to converter A to turn off. For example, the controller controls the switching devices in the positive switching unit K11 and the negative switching unit K12 to turn off, so that the first short-circuit current Ia is cut off, or simultaneously, the first short-circuit current Ia, the second short-circuit current Ib1, and the second short-circuit current Ib2 are cut off. The controller is also used to detect the second short-circuit current output by converter B, and when the magnitude of the second short-circuit current output by converter B is greater than a set current threshold, it determines that a second short-circuit current still exists between converter A and the parallel-connected converter B. The controller controls the switching devices in the positive switching unit K21 or the negative switching unit K22 connected to converter B to turn off, or controls the switching devices in the positive switching unit K21 and the negative switching unit K22 to turn off simultaneously, so as to cut off the second short-circuit current Ib1 and the second short-circuit current Ib2. Here, each converter obtains the voltage between the positive DC bus and the negative DC bus connected to each converter through its own controller, or through a single controller, to detect whether a short-circuit fault has occurred in each converter, and controls the switching devices in the positive and negative switching units connected to that converter to turn off when the voltage between the positive and negative DC buses connected to any converter is too low, thereby cutting off the short-circuit current between the faulty converter and the corresponding energy storage unit. In addition, the controller controls the switching devices of at least one of the positive and negative switching units connected to the converter that has not experienced a short-circuit fault to turn off, thereby cutting off the short-circuit current path between the power grid, the diffuser, and the faulty converter, preventing short-circuit current from interfering with the normal operation of the converter or even damaging the converter, and improving the reliability of the power supply system.

[0033] In some feasible implementations, the negative switching unit connected to each converter in the above-mentioned power supply system includes a reverse protection device, and the switching device in the positive switching unit is used to connect or disconnect the connection between the positive DC bus and the positive DC terminal of the corresponding converter when it is turned on or off. Figure 3 Taking the power supply system shown as an example, the negative switch unit K12 connected to converter A and the negative switch unit K22 connected to converter B include reverse polarity protection devices, while the positive switch unit K11 connected to converter A and the positive switch unit K21 connected to converter B are fast shutdown devices. Please refer to [the relevant documentation / reference]. Figure 4 , Figure 4 This is another structural schematic diagram of the power supply system provided in this application. Figure 4 In the power supply system shown, the switching devices in the positive switching unit K11 connected to converter A and the positive switching unit K21 connected to converter B are fast-shutdown devices. These fast-shutdown devices can be explosive fuses, excitation fuses, or other devices with fast-shutdown functions. The negative switching unit K12 connected to converter A includes a switching device and a reverse protection device. The switching device can be a semiconductor switch, and the reverse protection device is a diode connected in parallel with the semiconductor switch. The anode of this diode is connected to the cathode of the energy storage unit, and the cathode of the diode is connected to the negative DC terminal of converter A. Similarly, the negative switching unit K22 connected to converter B includes a semiconductor switch and a reverse protection device. The reverse protection device is a diode connected in parallel with the semiconductor switch, and the anode of this diode is connected to the cathode of the energy storage unit, and the cathode of the diode is connected to the negative DC terminal of converter B. (Controller) Figure 4(Not shown) The controller acquires the voltage between the positive and negative DC buses connected to each converter, and determines that a short-circuit fault has occurred in the converter when the voltage between the positive and negative DC buses connected to any converter is less than a set voltage threshold. For example, the controller acquires the voltage between the positive and negative DC buses connected to converter A, and if this voltage is lower than a set voltage threshold, it determines that converter A has a short-circuit fault. When converter A experiences a short-circuit fault, a first short-circuit current Ia appears in the power supply system. The first short-circuit current Ia may include the short-circuit current flowing from the positive terminal of the energy storage unit to the positive DC terminal of the first converter, and the short-circuit current flowing from the negative DC terminal of the first converter to the negative terminal of the energy storage unit. When a short-circuit fault occurs in converter A, since converter B is connected in parallel with converter A, a second short-circuit current Ib1 and a second short-circuit current Ib2 also appear in the power supply system. The second short-circuit current Ib1 flows from the positive DC terminal of converter B to the positive DC terminal of converter A, and the second short-circuit current Ib2 flows from the negative DC terminal of converter B to the negative DC terminal of converter A. Then, the controller can control the fast-shutdown device connected to the positive DC terminal of converter A to disconnect and control the semiconductor switch in the negative switching unit K12 to turn off. The aforementioned fast-shutdown device, when disconnected, disconnects the connection between the positive DC bus and the positive DC terminal of converter A, thereby cutting off the short-circuit current flowing from the positive terminal of the energy storage unit to the positive DC terminal of converter A in the first short-circuit current Ia, and the diode in the switching unit K12 cuts off the short-circuit current flowing from the negative DC terminal of the first converter to the negative terminal of the energy storage unit. The current path of the second short-circuit current Ib1 includes the fast-shutdown device connected to the positive DC terminal of converter A. Therefore, when the fast-shutdown device is disconnected, the second short-circuit current Ib1 is also cut off. After the semiconductor switch in the negative switching unit K12 is turned off, the second short-circuit current Ib2 flows from the positive terminal of the diode in the negative switching unit K12 to the negative terminal of the diode. That is, the direction of the second short-circuit current Ib2 is consistent with the conduction direction of the diode in the negative switching unit K12, so the second short-circuit current Ib2 cannot be cut off. When the magnitude of the second short-circuit current output by converter B is greater than the set current threshold, the controller determines that a second short-circuit current still exists between converter A and the parallel converter B. The controller controls the semiconductor switch in the negative switching unit K22 to turn off, and the second short-circuit current Ib2 flows from the negative terminal of the diode in the negative switching unit K22 to the positive terminal of the diode. That is, the diode in the negative switching unit K22 can reverse-directly cut off the second short-circuit current Ib2. Here, when a short-circuit fault occurs in the converter, the controller controls the switching devices in the positive and negative switching units connected to the converter to turn off, thereby cutting off the short-circuit current between the faulty converter and the corresponding energy storage unit.The controller also controls the switching devices of at least one of the positive and negative switching units connected to other converters to turn off when a short-circuit fault propagates. This cuts off the short-circuit current path between the power grid, the propagating machine, and the faulty converter, preventing the short-circuit current from interfering with the normal operation of the converter or even damaging it. Furthermore, as mentioned above... Figure 4 The switching devices in each negative switch unit are semiconductor switches. Semiconductor switches can achieve microsecond-level shutdown, which can ensure the speed of cutting off short-circuit current and prevent the faulty converter from being damaged by overcurrent. Figure 4 The switching devices in each positive switch unit are fast turn-off devices. When each converter is working normally, the fast turn-off device can reduce the loss of normal power current and ensure the power supply efficiency of the power supply system.

[0034] In some feasible implementations, both the positive and negative switching units connected to each converter in the above power supply system include reverse polarity protection devices. Please refer to [further details omitted]. Figure 5 , Figure 5 This is another structural schematic diagram of the power supply system provided in this application. Figure 5 In the power supply system shown, the positive switch unit K11 and negative switch unit K12 connected to converter A include switching devices and reverse protection devices. The switching devices can be semiconductor switches, and the reverse protection devices are diodes connected in parallel with the semiconductor switches. The anodes of the diodes in positive switch unit K11 and negative switch unit K12 are connected to the positive and negative terminals of the energy storage unit, respectively, and the cathodes of the diodes are connected to the positive and negative DC terminals of converter A, respectively. The positive switch unit K21 and negative switch unit K22 connected to converter B include switching devices and reverse protection devices. The switching devices can be semiconductor switches, and the reverse protection devices are diodes connected in parallel with the semiconductor switches. The anodes of the diodes in positive switch unit K21 and negative switch unit K22 are connected to the positive and negative terminals of the energy storage unit, respectively, and the cathodes of the diodes are connected to the positive and negative DC terminals of converter B, respectively. (Controller) Figure 5 (Not shown) The controller acquires the voltage between the positive and negative DC buses connected to each converter, and determines that a short-circuit fault has occurred in that converter when the voltage between the positive and negative DC buses connected to any converter is less than a set voltage threshold. For example, the controller acquires the voltage between the positive and negative DC buses connected to converter A, and if this voltage is lower than a set voltage threshold, it determines that converter A has a short-circuit fault. When converter A experiences a short-circuit fault, a first short-circuit current Ia, a second short-circuit current Ib1, and a second short-circuit current Ib2 appear in the power supply system, wherein the paths of each short-circuit current are as described above. Figure 4Similarly, this will not be repeated here. Next, the controller can turn off the semiconductor switch in the positive switching unit K11 and the semiconductor switch in the negative switching unit K12. The diode in switching unit K12 cuts off the short-circuit current flowing from the negative DC terminal of converter A to the negative terminal of the energy storage unit, thus cutting off the first short-circuit current Ia. After the semiconductor switch in the positive switching unit K11 is turned off, the second short-circuit current Ib1 flows from the anode to the cathode of the diode in the positive switching unit K11, meaning the direction of the second short-circuit current Ib1 is the same as the conduction direction of the diode in the positive switching unit K11, therefore the second short-circuit current Ib1 cannot be cut off. Similarly, after the semiconductor switch in the negative switching unit K12 is turned off, the second short-circuit current Ib2 flows from the anode to the cathode of the diode in the negative switching unit K12, meaning the direction of the second short-circuit current Ib2 is the same as the conduction direction of the diode in the negative switching unit K12, therefore the second short-circuit current Ib2 cannot be cut off. When the magnitude of the second short-circuit current output by converter B exceeds a set current threshold, the controller determines that a second short-circuit current still exists between converter A and the parallel-connected converter B. The controller then turns off the semiconductor switch in the negative switching unit K21, allowing the second short-circuit current Ib1 to flow from the negative terminal of the diode in the positive switching unit K21 to the positive terminal, meaning the diode in the positive switching unit K21 can reverse-block the second short-circuit current Ib1. Similarly, the controller turns off the semiconductor switch in the negative switching unit K22, allowing the second short-circuit current Ib2 to flow from the negative terminal of the diode in the negative switching unit K22 to the positive terminal, also meaning the diode in the negative switching unit K22 can reverse-block the second short-circuit current Ib2. In this scenario, when a short-circuit fault occurs in the converter, the controller turns off the switching devices in the positive and negative switching units connected to the converter, thereby cutting off the short-circuit current between the faulty converter and the corresponding energy storage unit. The controller also controls the switching devices of at least one of the positive and negative switching units connected to other converters to turn off when a short-circuit fault propagates. This cuts off the short-circuit current path between the power grid, the propagating machine, and the faulty converter, preventing the short-circuit current from interfering with the normal operation of the converter or even damaging it. Furthermore, the above... Figure 5 The switching devices in each switching unit are semiconductor switches. Semiconductor switches can achieve microsecond-level shutdown, which can ensure the speed of cutting off short-circuit current and prevent the faulty converter from being damaged by overcurrent.

[0035] In some feasible implementations, both the positive and negative switching units connected to each converter in the above power supply system include reverse polarity protection devices. Please refer to [further details omitted]. Figure 6 , Figure 6 This is another structural schematic diagram of the power supply system provided in this application. Figure 6In the power supply system shown, the positive switching unit K11 connected to converter A and the positive switching unit K21 connected to converter B include switching devices and reverse protection devices. The switching devices can be semiconductor switches, and the reverse protection devices are diodes connected in parallel with the semiconductor switches. The anodes of the diodes in positive switching units K11 and K21 are connected to the positive DC terminals of converter A and converter B, respectively, and the cathodes of the diodes are connected to the positive terminal of the energy storage unit. The negative switching units K12 connected to converter A and K22 connected to converter B include switching devices and reverse protection devices. The switching devices can be semiconductor switches, and the reverse protection devices are diodes connected in parallel with the semiconductor switches. The anodes of the diodes in negative switching units K12 and K22 are connected to the negative terminal of the energy storage unit, and the cathodes of the diodes are connected to the negative DC terminals of converter A and converter B, respectively. (Controller) Figure 6 (Not shown) The controller acquires the voltage between the positive and negative DC buses connected to each converter, and determines that a short-circuit fault has occurred in that converter when the voltage between the positive and negative DC buses connected to any converter is less than a set voltage threshold. For example, the controller acquires the voltage between the positive and negative DC buses connected to converter A, and if this voltage is lower than a set voltage threshold, it determines that converter A has a short-circuit fault. When converter A experiences a short-circuit fault, a first short-circuit current Ia, a second short-circuit current Ib1, and a second short-circuit current Ib2 appear in the power supply system, wherein the paths of each short-circuit current are as described above. Figure 4Similarly, this will not be repeated here. Next, the controller can control the semiconductor switch in the positive switching unit K11 to turn off and the semiconductor switch in the negative switching unit K12 to turn off. The diode in switching unit K11 blocks the short-circuit current flowing from the positive terminal of the energy storage unit to the positive DC terminal of the converter A, and the diode in switching unit K12 blocks the short-circuit current flowing from the negative DC terminal of the converter A to the negative terminal of the energy storage unit, thus cutting off the first short-circuit current Ia. After the semiconductor switch in the positive switching unit K11 is turned off, the second short-circuit current Ib1 flows from the negative terminal of the diode in the positive switching unit K11 to the positive terminal of the diode, meaning the diode in the positive switching unit K11 can reverse-block the second short-circuit current Ib1. After the semiconductor switch in the negative switching unit K12 is turned off, the second short-circuit current Ib2 flows from the positive terminal of the diode in the negative switching unit K12 to the negative terminal of the diode. That is, the direction of the second short-circuit current Ib2 is consistent with the conduction direction of the diode in the negative switching unit K12, therefore the second short-circuit current Ib2 cannot be cut off. When the magnitude of the second short-circuit current output by converter B is greater than the set current threshold, the controller determines that a second short-circuit current still exists between converter A and the parallel converter B. The controller controls the semiconductor switch in the negative switching unit K22 to turn off, and the second short-circuit current Ib2 flows from the negative terminal of the diode in the negative switching unit K22 to the positive terminal of the diode. That is, the diode in the negative switching unit K22 can reverse and cut off the second short-circuit current Ib2. Here, when a short-circuit fault occurs in the converter, the controller controls the switching devices in the positive and negative switching units connected to the converter to turn off, thereby cutting off the short-circuit current between the faulty converter and the corresponding energy storage unit. The controller also controls the switching devices of at least one of the positive and negative switching units connected to other converters to turn off when a short-circuit fault propagates. This cuts off the short-circuit current path between the power grid, the propagating machine, and the faulty converter, preventing the short-circuit current from interfering with the normal operation of the converter or even damaging it. Furthermore, the above... Figure 6 The switching devices in each switching unit are semiconductor switches. Semiconductor switches can achieve microsecond-level shutdown, which can ensure the speed of cutting off short-circuit current and prevent the faulty converter from being damaged by overcurrent.

[0036] In some feasible implementations, the switching devices in the first positive switching unit are used to cut off the current flowing into the positive DC terminal of the first converter when open, and the switching devices in the first negative switching unit are used to cut off the current flowing into the negative DC terminal of the first converter or the current flowing out of the negative DC terminal of the first converter when open. The controller is used to control the switching devices in the first positive and first negative switching units connected to the first converter to disconnect when the first converter is short-circuited. Each converter, through its own controller, or through a single controller, controls the switching devices in the positive and negative switching units connected to that converter to turn off when any converter is short-circuited, thereby cutting off the short-circuit current between the converter and the corresponding energy storage unit. Furthermore, when the switching device in the first positive switching unit is open, it cuts off the current flowing into the positive DC terminal of the first converter. Similarly, when the switching device in the first negative switching unit is open, it cuts off the current flowing into or out of the negative DC terminal of the first converter. Therefore, when the switching devices in the first positive and first negative switching units are open, the short-circuit current between the faulty converter and the corresponding energy storage unit, as well as the short-circuit current flowing between the power grid, the diffusion machine, and the faulty converter, can be simultaneously cut off. This prevents short-circuit current from interfering with the normal operation of the converter or even damaging it, thus improving the reliability of the power supply system.

[0037] In some feasible implementations, both the positive and negative switching units connected to each converter in the above power supply system include reverse polarity protection devices. Please refer to [further details omitted]. Figure 7 , Figure 7 This is another structural schematic diagram of the power supply system provided in this application. Figure 7 In the power supply system shown, the positive switch unit K11 and negative switch unit K12 connected to converter A include switching devices and reverse protection devices. The switching devices can be semiconductor switches, and the reverse protection devices are diodes connected in parallel with the semiconductor switches. The anodes of the diodes in positive switch unit K11 and negative switch unit K12 are connected to the positive DC terminal and negative DC terminal of converter A, respectively, and the cathodes of the diodes are connected to the positive and negative terminals of the energy storage unit, respectively. The positive switch unit K21 and negative switch unit K22 connected to converter B include switching devices and reverse protection devices. The switching devices can be semiconductor switches, and the reverse protection devices are diodes connected in parallel with the semiconductor switches. The anodes of the diodes in positive switch unit K21 and negative switch unit K22 are connected to the positive DC terminal and negative DC terminal of converter B, respectively, and the cathodes of the diodes are connected to the positive and negative terminals of the energy storage unit, respectively. (Controller) Figure 7(Not shown) The controller acquires the voltage between the positive and negative DC buses connected to each converter, and determines that a short-circuit fault has occurred in that converter when the voltage between the positive and negative DC buses connected to any converter is less than a set voltage threshold. For example, the controller acquires the voltage between the positive and negative DC buses connected to converter A, and if this voltage is lower than a set voltage threshold, it determines that converter A has a short-circuit fault. When converter A experiences a short-circuit fault, a first short-circuit current Ia, a second short-circuit current Ib1, and a second short-circuit current Ib2 appear in the power supply system, wherein the paths of each short-circuit current are as described above. Figure 4 Similarly, this will not be repeated here. Next, the controller can control the semiconductor switch in the positive switching unit K11 to turn off and the semiconductor switch in the negative switching unit K12 to turn off. The diode in switching unit K11 blocks the short-circuit current flowing from the positive terminal of the energy storage unit to the positive DC terminal of the converter A, thus cutting off the first short-circuit current Ia. After the semiconductor switch in the positive switching unit K11 turns off, the second short-circuit current Ib1 flows from the negative terminal of the diode in the positive switching unit K11 to the positive terminal, meaning the diode in the positive switching unit K11 can reverse-block the second short-circuit current Ib1. After the semiconductor switch in the negative switching unit K12 turns off, the second short-circuit current Ib2 flows from the negative terminal of the diode in the negative switching unit K12 to the positive terminal, meaning the diode in the negative switching unit K12 can reverse-block the second short-circuit current Ib2. Here, when a short-circuit fault occurs in the converter, the controller controls the switching devices in the positive and negative switching units connected to the converter to turn off, cutting off the short-circuit current between the faulty converter and the corresponding energy storage unit. At the same time, it can also cut off the short-circuit current path flowing between the power grid, the diffusion machine and the faulty converter. The operation is simple and prevents the short-circuit current from interfering with the normal operation of the converter or even damaging the converter.

[0038] In some feasible implementations, the switching devices in the negative switching units connected to each converter in the above power supply system are used to connect or disconnect the connection between the negative DC bus and the negative DC terminal of the corresponding converter, respectively, when the circuit is turned on or off. The positive switching unit includes a reverse protection device. Please refer to [further details omitted]. Figure 8 , Figure 8 This is another structural schematic diagram of the power supply system provided in this application. Figure 8In the power supply system shown, the switching devices in the negative switch unit K12 connected to converter A and the negative switch unit K22 connected to converter B are fast-shutdown devices, such as explosive fuses or excitation fuses. The positive switch unit K11 connected to converter A and the positive switch unit K21 connected to converter B include switching devices and reverse protection devices. The switching devices can be semiconductor switches, and the reverse protection devices are diodes connected in parallel with the semiconductor switches. The negative terminals of the diodes in positive switch units K11 and K21 are connected to the negative terminal of the energy storage unit, and the positive terminals of the diodes are connected to the positive DC terminals of converter A and converter B, respectively. (Controller) Figure 8 (Not shown) The controller acquires the voltage between the positive and negative DC buses connected to each converter, and determines that a short-circuit fault has occurred in that converter when the voltage between the positive and negative DC buses connected to any converter is less than a set voltage threshold. For example, the controller acquires the voltage between the positive and negative DC buses connected to converter A, and if this voltage is lower than a set voltage threshold, it determines that converter A has a short-circuit fault. When converter A experiences a short-circuit fault, a first short-circuit current Ia, a second short-circuit current Ib1, and a second short-circuit current Ib2 appear in the power supply system, wherein the paths of each short-circuit current are as described above. Figure 4 Similarly, this will not be repeated here. Next, the controller can disconnect the fast-shutdown device connected to the negative DC terminal of converter A and turn off the semiconductor switch in the positive switching unit K11. The diode in switching unit K11 cuts off the short-circuit current flowing from the positive terminal of the energy storage unit to the positive DC terminal of converter A, thus cutting off the first short-circuit current Ia. The current path of the aforementioned second short-circuit current Ib2 includes the fast-shutdown device connected to the negative DC terminal of converter A; therefore, after the fast-shutdown device is disconnected, the second short-circuit current Ib2 is also cut off. After the semiconductor switch in the positive switching unit K11 is turned off, the second short-circuit current Ib1 flows from the negative terminal of the diode in the positive switching unit K11 to the positive terminal of the diode; that is, the diode in the positive switching unit K11 can reverse-directively cut off the second short-circuit current Ib1. Here, when a short-circuit fault occurs in the converter, the controller controls the switching devices in the positive and negative switching units connected to the converter to turn off, cutting off the short-circuit current between the faulty converter and the corresponding energy storage unit. At the same time, it can also cut off the short-circuit current path flowing between the power grid, the diffusion machine and the faulty converter. The operation is simple and prevents the short-circuit current from interfering with the normal operation of the converter or even damaging the converter.

[0039] In some feasible implementations, the switching devices in the positive and negative switching units connected to each converter in the above power supply system are reverse-resistance type switching transistors. Specifically, the switching devices in the positive and negative switching units can be reverse-resistance type insulated-gate bipolar transistors (IGBTs) with bidirectional symmetrical blocking capability. Please refer to [further details omitted]. Figure 9 , Figure 9 This is another structural schematic diagram of the power supply system provided in this application. Figure 9 In the power supply system shown, the switching devices in the positive switching unit K11 and negative switching unit K12 connected to converter A are reverse-resistance type IGBTs, and the switching devices in the positive switching unit K21 and negative switching unit K22 connected to converter B are also reverse-resistance type IGBTs. Controller ( Figure 9 (Not shown) The controller acquires the voltage between the positive and negative DC buses connected to each converter, and determines that a short-circuit fault has occurred in that converter when the voltage between the positive and negative DC buses connected to any converter is less than a set voltage threshold. For example, the controller acquires the voltage between the positive and negative DC buses connected to converter A, and if this voltage is lower than a set voltage threshold, it determines that converter A has a short-circuit fault. When converter A experiences a short-circuit fault, a first short-circuit current Ia, a second short-circuit current Ib1, and a second short-circuit current Ib2 appear in the power supply system, wherein the paths of each short-circuit current are as described above. Figure 4 Similarly, this will not be repeated here. Next, the controller can disconnect the reverse-resistance IGBTs in the positive switch unit K11 and the negative switch unit K12, thus cutting off the first short-circuit current Ia. Since the reverse-resistance IGBTs have bidirectional symmetrical blocking capability, the reverse-resistance IGBT in the positive switch unit K11 can also reverse-block the second short-circuit current Ib1, and the reverse-resistance IGBT in the negative switch unit K12 can also reverse-block the second short-circuit current Ib2. Here, when a short-circuit fault occurs in the converter, the controller controls the switching devices in the positive and negative switch units connected to the converter to turn off, cutting off the short-circuit current between the faulty converter and the corresponding energy storage unit. Simultaneously, it can also cut off the short-circuit current path flowing between the grid, the diffusion machine, and the faulty converter. The operation is simple, preventing short-circuit current from interfering with the normal operation of the converter or even damaging it.

[0040] In some feasible implementations, a snubber circuit is connected to the two ends of the switching devices in the positive and negative switching units of each converter in the above-mentioned power supply system. This snubber circuit is used to absorb voltage spikes when the corresponding switching devices operate. Figure 4Taking the power supply system shown as an example, both the negative switch unit K12 connected to converter A and the negative switch unit K22 connected to converter B include semiconductor switches. These semiconductor switches operate quickly, and due to the presence of inductance and capacitance in the circuit where they operate, overvoltages can occur during operation, such as turn-off overvoltage and resonant overvoltage after turn-off. To address overvoltage scenarios, corresponding stress-absorbing circuits are connected across the semiconductor switches. Similarly, the switching devices in the positive switch unit K11 connected to converter A and the positive switch unit K21 connected to converter B are fast turn-off devices, and corresponding stress-absorbing circuits can also be connected across these fast turn-off devices. Please refer to [further details omitted]. Figure 10 , Figure 10 This is another structural schematic diagram of the power supply system provided in this application. Figure 10 In the power supply system shown, both the semiconductor switches in the negative switching unit K12 connected to converter A and the semiconductor switches in the negative switching unit K22 connected to converter B are connected in parallel with an absorption circuit. Similarly, the fast-turn-off devices in the positive switching unit K11 connected to converter A and the positive switching unit K21 connected to converter B are also connected in parallel with an absorption circuit. This absorption circuit is used to absorb voltage spikes when the corresponding semiconductor switch or fast-turn-off device operates, preventing overvoltage of the semiconductor switch or fast-turn-off device. Specifically, the absorption circuit can be an absorption circuit composed of a varistor, Zener diode, TVS diode, RCD circuit, or gas amplifier, or an absorption circuit composed of series and parallel combinations of the above devices. The specific choice depends on the actual application scenario and is not limited here.

Claims

1. A power supply system, characterized in that, The power supply system includes an energy storage unit, multiple converters, a controller, multiple positive switch units and multiple negative switch units corresponding to the multiple converters. The positive DC terminal of each converter is connected to the positive DC bus through the corresponding positive switch unit, and the negative DC terminal of each converter is connected to the negative DC bus through the corresponding negative switch unit. The positive DC bus and the negative DC bus are respectively connected to the positive and negative terminals of the energy storage unit. The positive DC terminal of the first converter in the plurality of converters is connected to the positive DC bus through the first positive switching unit in the plurality of positive switching units, and the negative DC terminal of the first converter is connected to the negative DC bus through the first negative switching unit in the plurality of negative switching units. The positive DC terminal of the second converter in the plurality of converters is connected to the positive DC bus through the second positive switching unit in the plurality of positive switching units, and the negative DC terminal of the second converter is connected to the negative DC bus through the second negative switching unit in the plurality of negative switching units. The controller is configured to, when the first converter is short-circuited, control the switching devices in the first positive switch unit and the first negative switch unit connected to the first converter to disconnect, and control the switching devices in the second positive switch unit and / or the second negative switch unit connected to the second converter to disconnect.

2. The power supply system according to claim 1, characterized in that, The controller is configured to, when the first converter is short-circuited, control the switching devices in the first positive switch unit and the first negative switch unit connected to the first converter to disconnect, and control the switching devices in the second positive switch unit and / or the second negative switch unit connected to the second converter to disconnect, including: When the voltage between the positive DC bus and the negative DC bus connected to the first converter is less than a set voltage threshold, the switching devices in the first positive switch unit and the first negative switch unit connected to the first converter are controlled to disconnect, and the switching devices in the second positive switch unit and / or the second negative switch unit connected to the second converter are controlled to disconnect.

3. The power supply system according to claim 1 or 2, characterized in that, The positive switch unit and / or the negative switch unit includes an anti-reverse device, which is used to cut off the short-circuit current when the switch device in the corresponding positive switch unit or negative switch unit is disconnected.

4. The power supply system according to claim 3, characterized in that, The negative switch unit includes the anti-reverse device, and the switch device in the positive switch unit is used to connect or disconnect the connection between the positive DC bus and the positive DC terminal of the first converter when it is turned on or off, respectively. The anti-reverse device in the first negative switch unit is used to cut off the short-circuit current flowing from the negative DC terminal of the first converter to the negative terminal of the energy storage unit when the switch device in the first negative switch unit is open. The anti-reverse device in the second negative switch unit is used to cut off the short-circuit current flowing from the negative DC terminal of the second converter to the negative DC terminal of the first converter when the switch device in the second negative switch unit is turned off.

5. The power supply system according to claim 3, characterized in that, The positive switch unit and the negative switch unit include the anti-reverse device; The anti-reverse device in the first negative switch unit is used to cut off the short-circuit current flowing from the negative DC terminal of the first converter to the negative terminal of the energy storage unit when the switch device in the first negative switch unit is open. The anti-reverse device in the second positive switch unit is used to cut off the short-circuit current flowing from the positive DC terminal of the second converter to the positive DC terminal of the first converter when the switch device in the second positive switch unit is open; The anti-reverse device in the second negative switch unit is used to cut off the short-circuit current flowing from the negative DC terminal of the second converter to the negative DC terminal of the first converter when the switch device in the corresponding negative switch unit is turned off.

6. The power supply system according to claim 3, characterized in that, The positive switch unit and the negative switch unit include the anti-reverse device; The anti-reverse device in the first positive switch unit is used to cut off the short-circuit current flowing from the positive terminal of the energy storage unit to the positive DC terminal of the first converter when the switch device in the first positive switch unit is turned off, and to cut off the short-circuit current flowing from the positive DC terminal of the second converter to the positive DC terminal of the first converter. The anti-reverse device in the first negative switch unit is used to cut off the short-circuit current flowing from the negative DC terminal of the first converter to the negative terminal of the energy storage unit when the switch device in the first negative switch unit is open. The anti-reverse device in the second negative switch unit is used to cut off the short-circuit current flowing from the negative DC terminal of the second converter to the negative DC terminal of the first converter when the switch device in the second negative switch unit is turned off.

7. The power supply system according to any one of claims 1-6, characterized in that, The energy storage unit and the plurality of converters are installed inside the container, and the AC terminals of the plurality of converters are connected to the power grid through interfaces on the container.

8. A power supply system, characterized in that, The power supply system includes an energy storage unit, multiple converters, a controller, multiple positive switch units and multiple negative switch units corresponding to the multiple converters. The positive DC terminal of each converter is connected to the positive DC bus through the corresponding positive switch unit, and the negative DC terminal of each converter is connected to the negative DC bus through the corresponding negative switch unit. The positive DC bus and the negative DC bus are respectively connected to the positive and negative terminals of the energy storage unit. The positive DC terminal of the first converter in the plurality of converters is connected to the positive DC bus through the first positive switching unit in the plurality of positive switching units, and the negative DC terminal of the first converter is connected to the negative DC bus through the first negative switching unit in the plurality of negative switching units. The positive DC terminal of the second converter in the plurality of converters is connected to the positive DC bus through the second positive switching unit in the plurality of positive switching units, and the negative DC terminal of the second converter is connected to the negative DC bus through the second negative switching unit in the plurality of negative switching units. The switching device in the first positive switch unit is used to cut off the current flowing into the positive DC terminal of the first converter when it is open, and the switching device in the first negative switch unit is used to cut off the current flowing into the negative DC terminal of the first converter or cut off the current flowing out of the negative DC terminal of the first converter when it is open. The controller is used to control the switching devices in the first positive switch unit and the first negative switch unit connected to the first converter to disconnect when the first converter is short-circuited.

9. The power supply system according to claim 8, characterized in that, The positive switch unit and the negative switch unit include anti-reverse devices; The anti-reverse device in the first positive switch unit is used to cut off the short-circuit current flowing from the positive terminal of the energy storage unit to the positive DC terminal of the first converter when the switch device in the first positive switch unit is turned off, and to cut off the short-circuit current flowing from the positive DC terminal of the second converter to the positive DC terminal of the first converter. The anti-reverse device in the first negative switch unit is used to cut off the short-circuit current flowing from the negative terminal of the energy storage unit to the negative DC terminal of the first converter when the switch device in the first negative switch unit is turned off, and to cut off the short-circuit current flowing from the negative DC terminal of the second converter to the negative DC terminal of the first converter.

10. The power supply system according to claim 8, characterized in that, The positive switch unit includes an anti-reverse device, and the switch device in the negative switch unit is used to connect or disconnect the connection between the negative DC bus and the negative DC terminal of the first converter when it is turned on or off, respectively. The anti-reverse device in the first positive switch unit is used to cut off the short-circuit current flowing from the positive terminal of the energy storage unit to the positive DC terminal of the first converter when the switch device in the first positive switch unit is turned off, and to cut off the short-circuit current flowing from the positive DC terminal of the second converter to the positive DC terminal of the first converter.

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