Energy storage system and fault isolation method thereof

Abstract

The present application relates to an energy storage system and a fault isolation method thereof. The energy storage system is provided with a first fuse device and a second fuse device connected between a battery cluster and a common DC bus, thyristors connected in parallel at both ends of an output capacitor of a power converter, and a low-voltage switching device and a power device are added to the power converter, wherein the third port of the power conversion circuit is connected to one end of the power device and one end of the output capacitor respectively through the low-voltage switching device, and the fourth port of the power conversion circuit is connected to the other end of the power device and the other end of the output capacitor respectively. The energy storage system can be used to provide overcurrent protection with the help of the thyristor, the low-voltage switching device and the power device in the event of a fault in the energy storage system, ultimately causing the first fuse device or the second fuse device to fuse, thereby achieving fault isolation. The thyristor and the power device are not lost during normal operation of the energy storage system, thereby reducing the cost of fault isolation.

Description

Technical Field

[0001] The present application relates to the field of energy storage technology, and in particular to an energy storage system and a fault isolation method thereof. Background Art

[0002] In existing energy storage systems, the output of the DC / DC converter is connected in series with the battery cluster circuit. Failure to implement effective protection and fault isolation strategies can lead to DC / DC converter burnout or even more serious failures if the system experiences a DC bus short circuit or a short circuit within the battery cluster. Currently, a solid-state IGBT (Insulated Gate Bipolar Transistor) is connected in series with the DC / DC converter input to protect the system in the event of a short circuit by shutting down the solid-state IGBT.

[0003] However, when the solid-state switch IGBT is connected in series in the circuit, the loss is large and there is also the problem of high cost. Summary of the Invention

[0004] Based on this, it is necessary to provide an energy storage system and a fault isolation method thereof that can reduce the fault isolation cost in response to the above technical problems.

[0005] In a first aspect, the present application provides an energy storage system, the energy storage system including a controller, a first fuse device, a second fuse device, a thyristor, a power converter, and a battery cluster, wherein the controller is connected to the thyristor and the power converter respectively;

[0006] The power converter includes a power conversion circuit, an output capacitor, a low-voltage switching device, and a power device; a controller is connected to the power conversion circuit and the low-voltage switching device, respectively; one end of the first fuse device is connected to the common DC bus of the battery cluster; one end of the second fuse device is connected to the common DC bus of the battery cluster; a third port of the power conversion circuit is connected to one end of the power device and one end of the output capacitor respectively through the low-voltage switching device; a fourth port of the power conversion circuit is connected to the other end of the power device and the other end of the output capacitor respectively; and a thyristor is connected in parallel at both ends of the output capacitor;

[0007] The first port of the power conversion circuit is connected to the other end of the first fuse device, and the second port of the power conversion circuit is connected to the other end of the second fuse device; or the first port of the power conversion circuit and the second port of the power conversion circuit are respectively connected to two ends of a power supply;

[0008] One end of the output capacitor is connected to the other end of the first fuse device through the battery cluster, and the other end of the output capacitor is connected to the other end of the second fuse device, or one end of the output capacitor is connected to the other end of the first fuse device, and the other end of the output capacitor is connected to the other end of the second fuse device through the battery cluster.

[0009] In one embodiment, the thyristor comprises a unidirectional thyristor;

[0010] The anode of the unidirectional thyristor is connected to one end of the power device and one end of the output capacitor respectively, the anode of the unidirectional thyristor is connected to the third port of the power conversion circuit through the low-voltage switching device, and the cathode of the unidirectional thyristor is connected to the fourth port of the power conversion circuit, the other end of the power device and the other end of the output capacitor respectively;

[0011] The anode of the one-way thyristor is further connected to the other end of the first fuse device through the battery cluster, or the cathode of the one-way thyristor is further connected to the other end of the second fuse device through the battery cluster.

[0012] In one embodiment, the low-voltage switching device includes a low-voltage MOS transistor;

[0013] The gate of the low-voltage MOS tube is connected to the controller, the drain of the low-voltage MOS tube is connected to the third port of the power conversion circuit, and the source of the low-voltage MOS tube is respectively connected to one end of the power device, one end of the output capacitor, and one end of the thyristor;

[0014] The source of the low-voltage MOS tube is further connected to the other end of the first fuse device through the battery cluster, or the source of the low-voltage MOS tube is further connected to the other end of the second fuse device through the output capacitor and the battery cluster in sequence.

[0015] In one embodiment, the power device includes a power diode;

[0016] The cathode of the power diode is connected to one end of the output capacitor and one end of the thyristor, respectively. The cathode of the power diode is connected to the third port of the power conversion circuit through the low-voltage switching device. The anode of the power diode is connected to the fourth port of the power conversion circuit, the other end of the output capacitor and the other end of the thyristor, respectively.

[0017] The cathode of the power diode is further connected to the other end of the first fuse device through the battery cluster, or the anode of the power diode is further connected to the other end of the second fuse device through the battery cluster.

[0018] In one embodiment, the power source includes a DC power source and an AC power source.

[0019] In a second aspect, the present application further provides a fault isolation method for an energy storage system, which is applied to a controller in the above-mentioned energy storage system; the method comprises:

[0020] obtaining a first voltage of a common DC bus of the battery cluster and a second voltage of the battery cluster;

[0021] If the energy storage system is confirmed to be in a first fault state based on the first voltage, the power conversion circuit is instructed to be blocked, and the duration is recorded. The current value flowing through the low-voltage switch device is obtained. If the current value is greater than or equal to the first protection threshold or the duration reaches a preset duration, the low-voltage switch device is controlled to be disconnected. The duration is used to represent the time between the power conversion circuit blocking and the low-voltage switch device disconnecting.

[0022] If the energy storage system is confirmed to be in the second fault state according to the second voltage, the power conversion circuit is instructed to block the wave and the voltage value of the output capacitor is obtained. When the voltage value is greater than or equal to the second protection threshold, the thyristor is controlled to be turned on.

[0023] In one embodiment, confirming that the energy storage system is in a first fault state based on the first voltage includes:

[0024] If the first voltage is less than the first value, it is confirmed that the energy storage system is in a first fault state.

[0025] In one embodiment, confirming that the energy storage system is in a first fault state based on the first voltage includes:

[0026] If the variation degree of the first voltage is greater than or equal to the first degree threshold, it is determined that the energy storage system is in a first fault state.

[0027] In one embodiment, confirming that the energy storage system is in the second fault state based on the second voltage includes:

[0028] If the second voltage is less than the second value, it is confirmed that the energy storage system is in the second fault state.

[0029] In one embodiment, confirming that the energy storage system is in the second fault state based on the second voltage includes:

[0030] If the variation degree of the second voltage is greater than or equal to the second degree threshold, it is confirmed that the energy storage system is in the second fault state.

[0031] The above energy storage system and fault isolation method thereof are provided by providing a controller, a first fuse device, a second fuse device, a thyristor, a power converter and a battery cluster in the energy storage system, and adding a low-voltage switch device and a power device in the power converter, wherein one end of the first fuse device is connected to the common DC bus of the battery cluster, one end of the second fuse device is connected to the common DC bus of the battery cluster, the third port of the power conversion circuit is respectively connected to one end of the power device and one end of the output capacitor through the low-voltage switch device, the fourth port of the power conversion circuit is respectively connected to the other end of the power device and the other end of the output capacitor, the two ends of the output capacitor are connected in parallel with the thyristor, the first port of the power conversion circuit is connected to the other end of the first fuse device, and the second port of the power conversion circuit is connected to the other end of the second fuse device; or, the first port of the power conversion circuit and the power converter are connected. The second port of the conversion circuit is respectively connected to the two ends of a power supply, and one end of the output capacitor is connected to the other end of the first fuse device through a battery cluster, and the other end of the output capacitor is connected to the other end of the second fuse device, or one end of the output capacitor is connected to the other end of the first fuse device, and the other end of the output capacitor is connected to the other end of the second fuse device through a battery cluster, so as to achieve fault isolation for the energy storage system; the present application uses thyristors, low-voltage switching devices and power devices to perform overcurrent protection in the event of a fault in the energy storage system, and finally causes the first fuse device or the second fuse device to melt, thereby achieving fault isolation. Compared with the solid-state switch IGBT used in the traditional method, the cost required for thyristors, low-voltage switching devices and power devices is lower, and the thyristors and power devices have no loss when the energy storage system is operating normally, thereby reducing the fault isolation cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following briefly introduces the drawings required for use in the embodiments of the present application or related technical descriptions. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying any creative work.

[0033] Figure 1 A schematic structural diagram of a series battery cluster balanced energy storage system according to an embodiment;

[0034] Figure 2 A schematic diagram of the flow of energy in an energy storage system with a solid-state switch IGBT connected in series when a DC bus short circuit occurs in one embodiment;

[0035] Figure 3 A schematic diagram of the flow of a battery cluster short circuit in an energy storage system with a solid-state switch IGBT connected in series according to one embodiment;

[0036] Figure 4A1. A schematic structural diagram of an energy storage system in which a power converter is connected to a common DC bus of a battery cluster via a first fuse device and a second fuse device, respectively, in one embodiment;

[0037] Figure 4B A schematic structural diagram of an energy storage system in another embodiment in which a power converter is connected to a common DC bus of a battery cluster via a first fuse device and a second fuse device respectively;

[0038] Figure 4C FIG1 is a schematic structural diagram of an energy storage system in which a power converter is connected to two ends of a power source in one embodiment;

[0039] Figure 4D FIG1 is a schematic structural diagram of an energy storage system in which a power converter is connected to two ends of a power source in another embodiment;

[0040] Figure 5 A schematic structural diagram of an energy storage system in another embodiment;

[0041] Figure 6 1 is a flow chart of a method for isolating a fault of an energy storage system according to an embodiment;

[0042] Figure 7 A schematic diagram of the flow direction when a DC bus short circuit occurs in an energy storage system according to one embodiment;

[0043] Figure 8 A schematic diagram of the flow of a battery cluster short circuit in an energy storage system according to one embodiment;

[0044] Figure 9 FIG. 4 is a structural block diagram of a fault isolation device for an energy storage system in one embodiment. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application pertains. The terms used herein are for the purpose of describing the embodiments of this application only and are not intended to limit this application.

[0047] It should be understood that terms such as "first" and "second" in this application are used only to distinguish similar objects and should not be understood to indicate or imply relative importance or implicitly indicate the number of technical features indicated. The "connection" appearing in the embodiments of this application refers to various connection methods, such as direct connection and indirect connection, to achieve communication between devices, and this embodiment of the application does not impose any limitation on this.

[0048] It will be understood that "at least one" means one or more, and "a plurality of" means two or more.

[0049] As used herein, the singular forms "a," "an," and "the" may also include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include," "comprising," "having," and the like specify the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof. Furthermore, the term "and / or" as used in this specification includes any and all combinations of the relevant listed items.

[0050] With the growing prosperity of the energy storage market, energy storage battery products are developing towards large capacity and high density. Large-capacity battery products and high-energy-density container energy storage systems can effectively reduce integration costs, reduce floor space, and shorten construction periods, thereby improving the economic benefits of energy storage systems. Figure 1 As shown, Figure 1 A series-type battery cluster balanced energy storage system is demonstrated as an example. Increasing the number of parallel battery clusters in the energy storage system can achieve an increase in power consumption under the same container size. However, this also brings the following difficulties: because the output end of the DC / DC converter is connected in series in the battery cluster circuit, when the energy storage system suffers a fault such as a short circuit on the DC bus side or a short circuit within the battery cluster, if effective protection and fault isolation strategies are not implemented, the DC / DC converter will burn out, or even lead to more serious faults.

[0051] Currently, to address the above problem, a solid-state switch IGBT is often connected in series on the output side of the DC / DC converter to achieve protection by turning off the solid-state switch IGBT in the event of a short-circuit fault.

[0052] In some examples, when a DC bus short circuit occurs, such as Figure 2 As shown, each battery cluster forms a short-circuit loop through the diodes connected in series with the DC / DC converter's output. This fault loop can be interrupted by shutting off the solid-state IGBTs (Insulated Gate Bipolar Transistors), preventing overcurrent damage to the DC / DC converter. The specific process is as follows: 1) When a DC bus short is detected, the low-voltage MOSFETs (S1 to S8) on the primary and secondary sides of the DC / DC converter are shut down. 2) After shutting down, the battery cluster forms a short-circuit loop through the short-circuit point and the body diodes of the low-voltage MOSFETs (S5 to S8) on the secondary side of the DC / DC converter, causing the current to rise. 3) When an overcurrent is detected in the secondary-side MOSFETs (S5 to S8) of the DC / DC converter, the solid-state IGBTs are shut off for protection.

[0053] In other examples, when any battery cluster is short-circuited, such as Figure 3 As shown, other battery clusters will form a short-circuit loop through the faulty battery cluster's short-circuit point and the capacitor on the output side of the series DC / DC converter. Turning off the solid-state IGBT (IGBT) disconnects the faulty loop, preventing overvoltage damage on the DC / DC converter's output side. The specific process is as follows: 1) When a short circuit is detected in this battery cluster, the low-voltage MOSFETs (S1 to S8) on the primary and secondary sides are muted. 2) Other battery clusters form a short-circuit loop through the short-circuit point of this cluster's cells and the output capacitor, causing the output capacitor voltage to surge. 3) When the output capacitor voltage reaches the overvoltage protection threshold, the solid-state IGBT (IGBT) is turned off, achieving protection.

[0054] However, the high-voltage solid-state switch IGBT solution has the advantages of fast protection speed and active short-circuit current limitation, but it also has the following disadvantages: 1) Solid-state switch IGBTs suitable for high voltage and high current are expensive; 2) Solid-state switch IGBTs are connected in series in the circuit, resulting in large losses and high heat dissipation costs; 3) There is a risk of overvoltage breakdown when the solid-state switch IGBT is turned off, requiring additional clamping circuits, absorption circuits or the use of solid-state switch IGBTs with higher voltage resistance, which increases costs.

[0055] The energy storage system provided in the embodiments of the present application adds thyristors, low-voltage switching devices, and power devices to the energy storage system. In the event of a fault in the energy storage system, overcurrent protection is provided by the thyristors, low-voltage switching devices, and power devices, ultimately causing the first fuse device or the second fuse device to blow, thereby achieving fault isolation. Compared with the solid-state switch IGBT used in traditional methods, the cost of the thyristors, low-voltage switching devices, and power diodes is lower, and the thyristors and power devices are all connected in parallel between the two ends of the output capacitor in the power converter. During normal operation of the energy storage system, the system does not operate, eliminating loss and heat dissipation risks. In addition, when the low-voltage switching device is shut down for protection, the short-circuit current can continue to flow through the added power device, thereby avoiding the overvoltage problem caused by shutdown.

[0056] In an exemplary embodiment, Figure 4A 、 Figure 4B 、 Figure 4C and Figure 4D As shown, an energy storage system is provided, which includes a controller, a first fuse device 410, a second fuse device 420, a thyristor 430, a power converter 440 and a battery cluster, wherein the controller is connected to the thyristor 430 and the power converter 440 respectively;

[0057] The power converter 440 includes a power conversion circuit 442, an output capacitor C out, low-voltage switch device 444 and power device 446; the controller is connected to the power conversion circuit 442 and the low-voltage switch device 444 respectively, one end of the first fuse device 410 is connected to the common DC bus of the battery cluster, one end of the second fuse device 420 is connected to the common DC bus of the battery cluster, and the third port of the power conversion circuit 442 is connected to one end of the power device 446 and the output capacitor C respectively through the low-voltage switch device 444. out The fourth port of the power conversion circuit 442 is connected to the other end of the power device 446 and the output capacitor C out The other end of the output capacitor C out The two ends of the circuit are connected in parallel with a thyristor 430;

[0058] The first port of the power conversion circuit 442 is connected to the other end of the first fuse device 410, and the second port of the power conversion circuit 442 is connected to the other end of the second fuse device 420; or, the first port of the power conversion circuit 442 and the second port of the power conversion circuit 442 are respectively connected to two ends of a power source;

[0059] Output capacitor C out One end of the output capacitor C is connected to the other end of the first fuse device 410 through the battery cluster. out The other end of the second fuse device 420 is connected to the other end of the output capacitor C out One end of the first fuse device 410 is connected to the other end of the output capacitor C out The other end of is connected to the other end of the second fuse device 420 through the battery cluster.

[0060] Among them, the power conversion circuit can be set according to actual conditions and is not limited in the embodiments of the present application; the first fuse device and the second fuse device can both refer to devices for circuit fusing. In the embodiments of the present application, the first fuse device and the second fuse device are taken as fuses as an example for explanation.

[0061] It should be noted that Figure 4A 、 Figure 4B 、 Figure 4C and Figure 4D The controller is not shown in the figure, and the patterns ①, ②, ③ and ④ in the power conversion circuit 442 correspond to the first port, the second port, the third port and the fourth port of the power conversion circuit 442 respectively; Figure 4A The structure shown is that the first port of the power conversion circuit 442 is connected to the other end of the first fuse device 410, the second port of the power conversion circuit 442 is connected to the other end of the second fuse device 420, and the output capacitor C out One end of the output capacitor C is connected to the other end of the first fuse device 410 through the battery cluster. out The other end of the second fuse device 420 is connected to the other end of the second fuse device 420; Figure 4B The structure shown is that the first port of the power conversion circuit 442 is connected to the other end of the first fuse device 410, the second port of the power conversion circuit 442 is connected to the other end of the second fuse device 420, and the output capacitor C out One end of the first fuse device 410 is connected to the other end of the output capacitor C out The other end is connected to the other end of the second fuse device 420 through the battery cluster; Figure 4C The structure shown is that the first port of the power conversion circuit 442 and the second port of the power conversion circuit 442 are connected to two ends of a power supply, and the output capacitor C out One end of the output capacitor C is connected to the other end of the first fuse device 410 through the battery cluster. out The other end of the second fuse device 420 is connected to the other end of the second fuse device 420; Figure 4D The structure shown is that the first port of the power conversion circuit 442 and the second port of the power conversion circuit 442 are connected to two ends of a power supply, and the output capacitor C out One end of the first fuse device 410 is connected to the other end of the output capacitor C out The other end of is connected to the other end of the second fuse device 420 through the battery cluster.

[0062] Specifically, Figure 4A The energy storage system in the example is used to illustrate that the energy storage system is provided with a thyristor 430, and the output capacitor C out When the voltage is too large, the controller can turn on the thyristor 430 and the output capacitor C out Discharge can be performed through the thyristor 430. When the short-circuit current increases to a certain level, the first fuse device 410 or the second fuse device 420 is blown to achieve protection. The power converter 440 in the energy storage system is provided with a power conversion circuit 442, an output capacitor C out , low-voltage switch device 444 and power device 446, the controller can achieve overcurrent protection by turning off the low-voltage switch device 444. During the process of turning off the low-voltage switch device 444, the short-circuit current will gradually be commutated to the power device 446. After the short-circuit current increases to a certain level, the first fuse device 410 or the second fuse device 420 is melted to achieve protection; wherein, Figure 4B 、 Figure 4C and Figure 4D The method for implementing protection in the energy storage system is similar to the above method and will not be repeated in the embodiments of this application.

[0063] Exemplarily, the power converter may be a DC / DC converter or an AC / DC converter, which is not limited in the embodiments of the present application.

[0064] In the above energy storage system, thyristors are connected in parallel across the output capacitor of the power converter, and a low-voltage switching device and a power device are added to the power converter. The third port of the power conversion circuit is connected to one end of the power device and one end of the output capacitor, respectively, through the low-voltage switching device, and the fourth port of the power conversion circuit is connected to the other end of the power device and the other end of the output capacitor, respectively, to achieve fault isolation of the energy storage system. Compared with the solid-state switch IGBT used in traditional methods, the cost of the thyristor, low-voltage switching device, and power device is lower, and the thyristor and power device are lossless during normal operation of the energy storage system, thereby reducing the cost of fault isolation.

[0065] In one embodiment, the power source includes a DC power source and an AC power source.

[0066] Specifically, the power source may be an alternating current power source (AC source), a direct current power source (DC source), or a battery cluster, which is not limited in the embodiments of the present application.

[0067] In one embodiment, Figure 5 As shown, thyristors include unidirectional thyristors SCR (Silicon Controlled Rectifier, thyristor rectifier);

[0068] The anode of the unidirectional thyristor SCR is connected to one end of the power device D1 and the output capacitor C out The anode of the unidirectional thyristor SCR is connected to the third port of the power conversion circuit through the low-voltage switch device Q1, and the cathode of the unidirectional thyristor SCR is connected to the fourth port of the power conversion circuit, the other end of the power device D1 and the output capacitor C out the other end;

[0069] The anode of the one-way thyristor SCR is further connected to the other end of the first fuse device F1 through the battery cluster, or the cathode of the one-way thyristor SCR is further connected to the other end of the second fuse device F2 through the battery cluster.

[0070] In the embodiment of the present application, the first fuse device is a battery cluster high voltage box fuse F1 and the second fuse device is a battery cluster high voltage box fuse F2 as an example for description.

[0071] It should be noted that Figure 5 For Figure 4A Further description of the energy storage system shown, Figure 4B 、 Figure 4C and Figure 4D The connection relationship of the components in the energy storage system shown is only described in text, wherein the anode of the thyristor SCR is also connected to the other end of the first fuse device F1 through the battery cluster, respectively corresponding to Figure 4A and Figure 4CIn the energy storage system, the cathode of the one-way thyristor SCR is also connected to the other end of the second fuse device F2 through the battery cluster, corresponding to Figure 4B and Figure 4D The energy storage system in the embodiment of the present application will not be described in detail.

[0072] Among them, such as Figure 5 As shown, the patterns ①, ②, ③ and ④ in the power conversion circuit correspond to the first port, the second port, the third port and the fourth port of the power conversion circuit 442 respectively.

[0073] Specifically, if Figure 5 As shown, in the case of a short circuit in the battery cluster, the controller can control other switch tubes in the power conversion circuit to block the wave and turn on the one-way thyristor SCR. Other battery clusters can form a short circuit loop through the short circuit point of the battery cluster and the one-way thyristor SCR, and the output capacitor C out The energy can be discharged through the one-way thyristor SCR; when the short-circuit current increases to a certain level, the input fuse F1 (first fuse device) of the battery cluster high-voltage box or the input fuse F2 (second fuse device) of the battery cluster high-voltage box will melt to achieve protection.

[0074] In the embodiment of the present application, the unidirectional thyristor SCR is connected in parallel between the first output terminal of the power converter and the second output terminal of the power converter. It does not work when the energy storage system is operating normally, and there is no loss and heat dissipation risk, thereby reducing costs.

[0075] In one embodiment, Figure 5 As shown, the low-voltage switch device includes a low-voltage MOS tube Q1;

[0076] The gate of the low-voltage MOS tube Q1 is connected to the controller, the drain of the low-voltage MOS tube Q1 is connected to the third port of the power conversion circuit, and the source of the low-voltage MOS tube Q1 is connected to one end of the power device D1 and the output capacitor C out One end of the thyristor and one end of the SCR;

[0077] The source of the low voltage MOS transistor Q1 is also connected to the other end of the first fuse device F1 through the battery cluster, or the source of the low voltage MOS transistor Q1 is also connected to the other end of the first fuse device F1 through the output capacitor C out The battery cluster is connected to the other end of the second fuse device F2.

[0078] It should be noted that the source of the low voltage MOS tube Q1 is also connected to the other end of the first fuse device F1 through the battery cluster, corresponding to Figure 4A and Figure 4C In the energy storage system, the source of the low-voltage MOS tube Q1 is also connected to the output capacitor C out The other end of the battery cluster connected to the second fuse device F2 corresponds to Figure 4Band Figure 4D The energy storage system in the embodiment of the present application will not be described in detail.

[0079] Specifically, if Figure 5 As shown in the figure, when the DC bus (PBUS+, PBUS-) is short-circuited, the controller can control other switching tubes in the power conversion circuit to block the wave and turn off the low-voltage MOS tube Q1 to achieve overcurrent protection.

[0080] In the embodiment of the present application, when the low-voltage MOS tube is turned off for protection, the short-circuit current can continue to flow through the power device, thereby avoiding the overvoltage problem of turning off the solid-state switch IGBT in the traditional way.

[0081] In one embodiment, Figure 5 As shown, the power device includes a power diode D1;

[0082] The cathode of power diode D1 is connected to output capacitor C out The cathode of the power diode D1 is connected to the third port of the power conversion circuit through the low-voltage switch device Q1, and the anode of the power diode D1 is connected to the fourth port of the power conversion circuit and the output capacitor C out The other end of the thyristor SCR;

[0083] The cathode of the power diode D1 is further connected to the other end of the first fuse device F1 through the battery cluster, or the anode of the power diode D1 is further connected to the other end of the second fuse device F2 through the battery cluster.

[0084] It should be noted that the cathode of the power diode D1 is also connected to the other end of the first fuse device F1 through the battery cluster, respectively corresponding to Figure 4A and Figure 4C In the energy storage system, the anode of the power diode D1 is also connected to the other end of the second fuse device F2 through the battery cluster, respectively corresponding to Figure 4B and Figure 4D The energy storage system in the embodiment of the present application will not be described in detail.

[0085] Specifically, if Figure 5As shown in the figure, when a short circuit occurs in the DC bus (PBUS+, PBUS-), the controller can control the other switching tubes in the power conversion circuit to block the current and turn off the low-voltage MOS tube Q1 to achieve overcurrent protection. During the process of turning off the low-voltage MOS tube Q1, the short-circuit current will gradually commutate to the branch where the diode D1 is located. Therefore, no high overvoltage will be generated when the low-voltage MOS tube Q1 is turned off. The short-circuit current flowing through the diode D1 gradually increases and eventually melts the input fuse F1 (first fuse device) or the input fuse F2 (second fuse device) of the battery cluster high-voltage box to achieve protection. It should be noted that the melting integral value of the diode D1 (I 2 t value) must be greater than the melting integral value of the fuse.

[0086] For example, the power device can be replaced by a thyristor (SCR) and a corresponding driving circuit, and the overcurrent protection and short-circuit current output can be achieved by cooperating with the low-voltage MOS tube Q1, which is not limited in the embodiments of the present application.

[0087] In the embodiment of the present application, the power diode is connected in parallel between the first output terminal of the power converter and the second output terminal of the power converter, and does not work when the energy storage system is operating normally, so there is no loss and heat dissipation risk, which reduces costs.

[0088] In an exemplary embodiment, Figure 6 As shown, a fault isolation method for an energy storage system is provided, which is applied to a controller in the above energy storage system; the method includes:

[0089] S602 : Acquire a first voltage of a common DC bus of the battery cluster and a second voltage of the battery cluster.

[0090] Specifically, the controller can obtain the voltage corresponding to the positive pole (PBUS+) of the common DC bus of the battery cluster and the voltage corresponding to the negative pole (PBUS-) of the common DC bus of the battery cluster, and use the difference between the two as the first voltage. The controller can also obtain the second voltage of the battery cluster.

[0091] S604: If the energy storage system is confirmed to be in a first fault state based on the first voltage, the power conversion circuit is instructed to be blocked, and the duration is recorded. The current value flowing through the low-voltage switch device is obtained. If the current value is greater than or equal to the first protection threshold or the duration reaches a preset duration, the low-voltage switch device is controlled to be disconnected. The duration is used to represent the time from the blocking of the power conversion circuit to the disconnection of the low-voltage switch device.

[0092] Among them, the first protection threshold and the preset duration can be set according to actual conditions and are not limited in the embodiments of the present application.

[0093] Specifically, the first fault state may be a fault state corresponding to a DC bus short circuit, such as Figure 7 As shown, the controller can instruct the switch tube in the power conversion circuit to block the wave when it is confirmed that the DC bus is short-circuited according to the first voltage, wait for the switch tube (S1 to S8) in the power conversion circuit to be turned off, and when the output capacitor C out After the battery is discharged through the DC bus, the anode of the battery cluster will return to the cathode of the battery cluster through the short-circuit point of the DC bus and diode D1 in turn (such as Figure 7 On the other hand, the anode of the battery cluster also returns to the cathode of the battery cluster through the short-circuit point of the DC bus, the body diodes of the switches S5 to S8 in the power conversion circuit, and the low-voltage MOSFET Q1 (low-voltage switching device). The controller can obtain the current flowing through the low-voltage MOSFET Q1 and, if the current value is greater than or equal to the first protection threshold or the current duration reaches a preset time, control the low-voltage MOSFET Q1 to disconnect, thereby achieving overcurrent protection. During the shutdown process of the low-voltage MOSFET Q1, the short-circuit current gradually commutates to the branch where the power diode D1 (power device) is located. Therefore, when the low-voltage MOSFET Q1 is turned off, no high overvoltage is generated. The short-circuit current flowing through the power diode D1 gradually increases, eventually blowing the input fuse F1 (first fuse device) or the input fuse F2 (second fuse device) of the battery cluster high-voltage box, thereby achieving protection. In other words, by detecting the busbar short circuit or output overcurrent and coordinating the corresponding protection action sequence, fault isolation is achieved.

[0094] For example, if the duration reaches a preset duration, it can be indicated that the switch tubes S1 to S8 in the power conversion circuit are completely locked. At this time, the low-voltage MOS tube Q1 is controlled to be disconnected to achieve overcurrent protection.

[0095] It should be noted that Figure 7 The circuit structure within the medium power conversion circuit is merely an exemplary structure and is not intended to limit the present application.

[0096] In one embodiment, confirming that the energy storage system is in a first fault state based on the first voltage includes:

[0097] If the first voltage is less than the first value, it is confirmed that the energy storage system is in a first fault state.

[0098] Among them, the first value can be set according to actual conditions and is not used to limit this application.

[0099] Specifically, when the energy storage system is operating normally, the first voltage should be within a normal range. If it is detected that the first voltage is less than the voltage threshold (first value) of the short-circuit protection, it can be determined that the DC bus is short-circuited, that is, it is confirmed that the energy storage system is in the first fault state.

[0100] In one embodiment, confirming that the energy storage system is in a first fault state based on the first voltage includes:

[0101] If the variation degree of the first voltage is greater than or equal to the first degree threshold, it is determined that the energy storage system is in a first fault state.

[0102] The first degree threshold can be set according to actual conditions and is not intended to limit this application.

[0103] Specifically, the controller can detect the voltage drop change rate of the first voltage. When the voltage drop slope (change degree) is greater than or equal to the first degree threshold, it can also determine that the DC bus is short-circuited, that is, confirm that the energy storage system is in the first fault state.

[0104] S606: If the energy storage system is confirmed to be in the second fault state according to the second voltage, the power conversion circuit is instructed to shut down, and the voltage value of the output capacitor is obtained. When the voltage value is greater than or equal to the second protection threshold, the thyristor is controlled to be turned on.

[0105] Among them, the second protection threshold can be set according to actual conditions and is not limited in the embodiments of the present application.

[0106] Specifically, the second fault state may be a fault state corresponding to a short circuit of the battery cluster, such as Figure 8 As shown, when the controller confirms that a battery cluster short circuit occurs based on the second voltage, it can instruct the switch tube in the power conversion circuit to block the wave, and wait for the switch tubes (S1 to S8) in the power conversion circuit to be closed. Then, other battery clusters on the DC bus will pass through the short-circuit point of the faulty battery cluster and the output capacitor C out Forming a loop, the output capacitor C out The voltage rises rapidly, and the voltage value of the output capacitor is obtained. When the voltage value is greater than or equal to the second protection threshold, the thyristor SCR is controlled to turn on, and other battery clusters form a short-circuit loop through the short-circuit point of the battery in this cluster and the thyristor SCR. The output capacitor C out The energy is discharged through the thyristor SCR (such as Figure 8 When the short-circuit current increases to a certain level, the input fuse (fusing device) of the battery cluster high-voltage box blows, providing protection. That is, fault isolation is achieved by detecting a short circuit within the battery cluster or output overvoltage, and coordinating the corresponding protection action sequence.

[0107] It should be noted that Figure 8 The circuit structure within the medium power conversion circuit is merely an exemplary structure and is not intended to limit the present application.

[0108] In one embodiment, confirming that the energy storage system is in the second fault state based on the second voltage includes:

[0109] If the second voltage is less than the second value, it is confirmed that the energy storage system is in the second fault state.

[0110] The second value can be set according to actual conditions and is not used to limit this application.

[0111] Specifically, when the energy storage system is operating normally, the second voltage should be within a normal range. If the second voltage is detected to be less than the short-circuit protection voltage threshold (the second value), it can be determined that the battery cluster is short-circuited, that is, the energy storage system is confirmed to be in the second fault state.

[0112] In one embodiment, confirming that the energy storage system is in the second fault state based on the second voltage includes:

[0113] If the variation degree of the second voltage is greater than or equal to the second degree threshold, it is confirmed that the energy storage system is in the second fault state.

[0114] The second degree threshold can be set according to actual conditions and is not intended to limit this application.

[0115] Specifically, the controller can detect the voltage drop change rate of the second voltage. When the voltage drop slope (change degree) is greater than or equal to the second degree threshold, it can also determine that the battery cluster is short-circuited, that is, confirm that the energy storage system is in the second fault state.

[0116] It should be understood that, although the various steps in the flowcharts involved in the various embodiments described above are displayed in sequence according to the instructions of the arrows, these steps are not necessarily executed in sequence in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and these steps can be executed in other orders. Moreover, at least a portion of the steps in the flowcharts involved in the various embodiments described above can include multiple steps or multiple stages, and these steps or stages are not necessarily executed and completed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a portion of steps or stages in other steps.

[0117] Based on the same inventive concept, embodiments of the present application also provide a fault isolation device for an energy storage system for implementing the aforementioned method for isolating an energy storage system. The solution provided by this device is similar to the solution described in the aforementioned method. Therefore, the specific limitations of one or more embodiments of the fault isolation device for an energy storage system provided below can be found in the aforementioned definition of the method for isolating an energy storage system, and will not be further elaborated here.

[0118] In an exemplary embodiment, Figure 9As shown, a fault isolation device 900 for an energy storage system is provided, comprising:

[0119] The acquisition module 901 is configured to acquire a first voltage of a common DC bus of a battery cluster and a second voltage of the battery cluster.

[0120] Confirmation module 902 is used to, if it is confirmed based on the first voltage that the energy storage system is in the first fault state, instruct the power conversion circuit to be blocked, record the duration, obtain the current value flowing through the low-voltage switching device, and control the low-voltage switching device to be disconnected when the current value is greater than or equal to the first protection threshold or the duration reaches a preset duration; wherein the duration is used to represent the time between the blocking of the power conversion circuit and the disconnection of the low-voltage switching device.

[0121] The confirmation module 902 is further configured to, if it is determined based on the second voltage that the energy storage system is in the second fault state, instruct the power conversion circuit to block the wave, obtain the voltage value of the output capacitor, and control the thyristor to conduct when the voltage value is greater than or equal to the second protection threshold.

[0122] In one embodiment, the confirmation module 902 is further configured to confirm that the energy storage system is in a first fault state if the first voltage is less than a first value.

[0123] In one embodiment, the confirmation module 902 is further configured to confirm that the energy storage system is in a first fault state if the variation degree of the first voltage is greater than or equal to a first degree threshold.

[0124] In one embodiment, the confirmation module 902 is further configured to confirm that the energy storage system is in a second fault state if the second voltage is less than a second value.

[0125] In one embodiment, the confirmation module 902 is further configured to confirm that the energy storage system is in a second fault state if the variation degree of the second voltage is greater than or equal to a second degree threshold.

[0126] Each module in the fault isolation device of the energy storage system described above can be implemented in whole or in part through software, hardware, or a combination thereof. Each module can be embedded in or independent of a processor in a computer device in hardware form, or stored in a computer device memory in software form, so that the processor can call and execute the corresponding operations of each module.

[0127] In an exemplary embodiment, a computer device is provided, including a memory and a processor. The memory stores a computer program, and the processor implements the above-mentioned energy storage system fault isolation method when executing the computer program.

[0128] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the above-mentioned fault isolation method of the energy storage system is implemented.

[0129] In one embodiment, a computer program product is provided, including a computer program, which implements the above-mentioned fault isolation method for the energy storage system when executed by a processor.

[0130] It should be noted that the data involved in this application (including but not limited to data used for analysis, stored data, displayed data, etc.) are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of relevant data must comply with relevant regulations.

[0131] Those skilled in the art will understand that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. In particular, any reference to memory, database, or other media used in the embodiments provided in this application can include at least one of non-volatile memory and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The databases involved in the various embodiments provided herein may include at least one of a relational database and a non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the various embodiments provided herein may be, but are not limited to, general-purpose processors, central processing units (CPUs), graphics processing units (GPUs), digital signal processors (DSPs), programmable logic devices (PLDs), quantum computing-based data processing logic devices, artificial intelligence (AI) processors, and the like.

[0132] The technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0133] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be determined by the appended claims.

Claims

1. An energy storage system, characterized in that: The energy storage system includes a controller, a first fuse device, a second fuse device, a thyristor, a power converter and a battery cluster, wherein the controller is connected to the thyristor and the power converter respectively; The power converter includes a power conversion circuit, an output capacitor, a low-voltage switching device, and a power device; the controller is connected to the power conversion circuit and the low-voltage switching device respectively; one end of the first fuse device is connected to the common DC bus of the battery cluster; one end of the second fuse device is connected to the common DC bus of the battery cluster; the third port of the power conversion circuit is connected to one end of the power device and one end of the output capacitor respectively through the low-voltage switching device; the fourth port of the power conversion circuit is connected to the other end of the power device and the other end of the output capacitor respectively; the two ends of the output capacitor are connected in parallel with the thyristor; The first port of the power conversion circuit is connected to the other end of the first fuse device, and the second port of the power conversion circuit is connected to the other end of the second fuse device; or the first port of the power conversion circuit and the second port of the power conversion circuit are respectively connected to two ends of a power supply; One end of the output capacitor is connected to the other end of the first fuse device through the battery cluster, and the other end of the output capacitor is connected to the other end of the second fuse device, or one end of the output capacitor is connected to the other end of the first fuse device, and the other end of the output capacitor is connected to the other end of the second fuse device through the battery cluster.

2. The energy storage system according to claim 1, characterized in that The thyristor includes a unidirectional thyristor; The anode of the unidirectional thyristor is connected to one end of the power device and one end of the output capacitor respectively, the anode of the unidirectional thyristor is connected to the third port of the power conversion circuit through the low-voltage switch device, and the cathode of the unidirectional thyristor is connected to the fourth port of the power conversion circuit, the other end of the power device and the other end of the output capacitor respectively; The anode of the one-way thyristor is further connected to the other end of the first fuse device through the battery cluster, or the cathode of the one-way thyristor is further connected to the other end of the second fuse device through the battery cluster.

3. The energy storage system according to claim 1, characterized in that The low-voltage switch device includes a low-voltage MOS tube; The gate of the low-voltage MOS transistor is connected to the controller, the drain of the low-voltage MOS transistor is connected to the third port of the power conversion circuit, and the source of the low-voltage MOS transistor is respectively connected to one end of the power device, one end of the output capacitor, and one end of the thyristor; The source of the low-voltage MOS transistor is further connected to the other end of the first fuse device through the battery cluster, or the source of the low-voltage MOS transistor is further connected to the other end of the second fuse device through the output capacitor and the battery cluster in sequence.

4. The energy storage system according to claim 1, characterized in that The power device includes a power diode; The cathode of the power diode is connected to one end of the output capacitor and one end of the thyristor, respectively; the cathode of the power diode is connected to the third port of the power conversion circuit through the low-voltage switching device; and the anode of the power diode is connected to the fourth port of the power conversion circuit, the other end of the output capacitor, and the other end of the thyristor, respectively; The cathode of the power diode is further connected to the other end of the first fuse device through the battery cluster, or the anode of the power diode is further connected to the other end of the second fuse device through the battery cluster.

5. The energy storage system according to claim 1, characterized in that: The power supply includes a direct current power supply and an alternating current power supply.

6. A fault isolation method for an energy storage system, characterized in that: The method is applied to the controller in the energy storage system according to any one of claims 1 or 5; the method comprises: Acquiring a first voltage of a common DC bus of the battery cluster and a second voltage of the battery cluster; If the energy storage system is confirmed to be in a first fault state based on the first voltage, the power conversion circuit is instructed to be blocked, and the duration is recorded, and a current value flowing through the low-voltage switch device is obtained. If the current value is greater than or equal to a first protection threshold or the duration reaches a preset duration, the low-voltage switch device is controlled to be disconnected; wherein the duration is used to represent the time from the blocking of the power conversion circuit to the disconnection of the low-voltage switch device; If the energy storage system is confirmed to be in the second fault state according to the second voltage, the power conversion circuit is instructed to block the wave, and the voltage value of the output capacitor is obtained. When the voltage value is greater than or equal to the second protection threshold, the thyristor is controlled to be turned on.

7. The method according to claim 6, characterized in that The confirming, based on the first voltage, that the energy storage system is in a first fault state includes: If the first voltage is less than a first value, it is confirmed that the energy storage system is in the first fault state.

8. The method according to claim 6, characterized in that The confirming, based on the first voltage, that the energy storage system is in a first fault state includes: If the variation degree of the first voltage is greater than or equal to a first degree threshold, it is confirmed that the energy storage system is in the first fault state.

9. The method according to claim 6, characterized in that Confirming that the energy storage system is in a second fault state according to the second voltage includes: If the second voltage is less than a second value, it is confirmed that the energy storage system is in the second fault state.

10. The method according to claim 6, characterized in that Confirming that the energy storage system is in a second fault state according to the second voltage includes: If the variation degree of the second voltage is greater than or equal to a second degree threshold, it is confirmed that the energy storage system is in the second fault state.

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