Overvoltage protection method and device, computer equipment and storage medium

Abstract

The invention relates to an overvoltage protection method and device, computer equipment and a storage medium, which are applied to a high-voltage direct hanging type energy storage system, and the high-voltage direct hanging type energy storage system comprises a power unit and an energy storage unit. The method comprises the following steps: acquiring a first voltage of a bus side of the high-voltage direct-hanging type energy storage system, and determining whether overvoltage occurs in the high-voltage direct-hanging type energy storage system according to the first voltage and a preset threshold value; therefore, under the condition that overvoltage occurs in the high-voltage direct-hanging type energy storage system, the access between the power unit and the energy storage unit is disconnected. By adopting the method, overvoltage protection can be carried out on the high-voltage direct-hanging type energy storage system.

Description

Overvoltage protection method, device, computer equipment and storage medium Technical Field

[0001] The present application relates to the field of electric power technology, and in particular to an overvoltage protection method, device, computer equipment, and storage medium. Background Art

[0002] High-voltage direct-mounted energy storage systems are a new type of energy storage system that utilizes modular multi-level cascade technology to cascade multiple energy storage modules. Each module consists of a power unit and an energy storage unit, which includes a battery pack. Because high-voltage direct-mounted energy storage systems can simultaneously achieve AC / DC power conversion and energy storage, and offer advantages such as high modularity, good harmonic characteristics, and low equivalent switching frequency, they are increasingly being used in power grids.

[0003] Due to external factors such as switching operations or internal factors such as ground faults, high-voltage direct-mounted energy storage systems will generate overvoltage. However, the transient overvoltage stress of the battery pack in the energy storage unit is very low, and the battery pack is prone to failure under the action of overvoltage, resulting in abnormalities in the high-voltage direct-mounted energy storage system.

[0004] Therefore, how to perform overvoltage protection on high-voltage direct-mounted energy storage systems has become a key research topic for researchers in this field.

[0005] Summary of the Invention

[0006] Based on this, it is necessary to provide an overvoltage protection method, device, computer equipment and storage medium that can provide overvoltage protection for high-voltage direct-mounted energy storage systems in response to the above technical problems.

[0007] In a first aspect, the present application provides an overvoltage protection method for a high-voltage direct-mounted energy storage system, the high-voltage direct-mounted energy storage system comprising a power unit and an energy storage unit. The method comprises:

[0008] Obtaining a first voltage on a bus side of the high-voltage direct-mounted energy storage system;

[0009] Determining whether an overvoltage occurs in the high-voltage direct-mounted energy storage system based on the first voltage and a preset threshold;

[0010] When an overvoltage occurs in the high-voltage direct-mounted energy storage system, the path between the power unit and the energy storage unit is disconnected.

[0011] The above-mentioned overvoltage protection method is applied to a high-voltage direct-mounted energy storage system, which includes a power unit and an energy storage unit. The method first obtains the first voltage on the bus side of the high-voltage direct-mounted energy storage system, and then determines whether the high-voltage direct-mounted energy storage system has an overvoltage based on the first voltage and a preset threshold value, so that when the high-voltage direct-mounted energy storage system has an overvoltage, the path between the power unit and the energy storage unit is disconnected. Since the present application can judge the overvoltage state of the high-voltage direct-mounted energy storage system based on the first voltage on the bus side of the high-voltage direct-mounted energy storage system and the preset threshold value, and then determine whether the high-voltage direct-mounted energy storage system has an overvoltage. In addition, the present application can disconnect the path between the power unit and the energy storage unit when it is determined that the high-voltage direct-mounted energy storage system has an overvoltage. Therefore, the present application can temporarily remove the energy storage unit from the high-voltage direct-mounted energy storage system in a timely manner when the high-voltage direct-mounted energy storage system generates an overvoltage, that is, temporarily remove the battery pack in the energy storage unit from the high-voltage direct-mounted energy storage system in a timely manner. Therefore, the method provided by the present application solves the problem that when a high-voltage direct-mounted energy storage system generates an overvoltage, the battery pack in the energy storage unit has a very low transient overvoltage stress, causing the battery pack to fail under the action of overvoltage and causing the high-voltage direct-mounted energy storage system to be abnormal. It provides a method for overvoltage protection for the high-voltage direct-mounted energy storage system, thereby improving the operational stability and safety of the high-voltage direct-mounted energy storage system. In addition, since the present application does not require major changes to the circuit, only the path between the power unit and the energy storage unit is disconnected, and the battery pack in the energy storage unit can be temporarily removed from the high-voltage direct-mounted energy storage system in a timely manner. Therefore, the overvoltage protection method provided by the present application is a convenient, fast-acting, and small-change method.

[0012] In one embodiment, determining whether the high-voltage direct-mounted energy storage system has an overvoltage based on the first voltage and a preset threshold value includes:

[0013] If the first voltage includes multiple bus voltages collected within a preset time period, it is determined whether the high-voltage direct-mounted energy storage system has an overvoltage based on the multiple bus voltages and the preset threshold.

[0014] On the one hand, the above embodiment avoids the problem of low accuracy when determining whether a high-voltage direct-mounted energy storage system has an overvoltage based on a bus voltage and a preset threshold value. On the other hand, it determines whether a high-voltage direct-mounted energy storage system has an overvoltage based on multiple bus voltages collected within a preset time period. When an overvoltage occurs in the high-voltage direct-mounted energy storage system, the path between the power unit and the energy storage unit is disconnected, and the operating state of the high-voltage direct-mounted energy storage system is not frequently changed, thereby further improving the safety and stability of the high-voltage direct-mounted energy storage system.

[0015] In one embodiment, determining whether the high-voltage direct-mounted energy storage system has an overvoltage according to the multiple bus voltages and the preset threshold value includes:

[0016] When the multiple bus voltages are all greater than a first preset threshold, determining that an overvoltage occurs in the high-voltage direct-mounted energy storage system;

[0017] When the multiple bus voltages are all less than the first preset threshold, it is determined that the high-voltage direct-mounted energy storage system does not have an overvoltage.

[0018] In the above embodiment, since it is possible to determine whether an overvoltage has occurred in the high-voltage direct-mounted energy storage system based on the comparison results of multiple bus voltages with the first preset threshold value, the accuracy of detecting an overvoltage in the high-voltage direct-mounted energy storage system is improved, and the speed of determining an overvoltage in the high-voltage direct-mounted energy storage system is also improved. Therefore, when an overvoltage occurs in the high-voltage direct-mounted energy storage system, the control system can promptly disconnect the path between the power unit and the energy storage unit.

[0019] In one embodiment, determining whether the high-voltage direct-mounted energy storage system has an overvoltage according to the multiple bus voltages and the preset threshold value includes:

[0020] Obtaining multiple time derivatives of the multiple bus voltages after derivation with respect to time;

[0021] When the multiple bus voltages are all greater than the first preset threshold, and the multiple time derivatives are all greater than the second preset threshold, it is determined that the high-voltage direct-mounted energy storage system has an overvoltage;

[0022] When the multiple bus voltages are not greater than the first preset threshold, and the multiple time derivatives are not greater than the second preset threshold, it is determined that the high-voltage direct-mounted energy storage system does not have an overvoltage.

[0023] Since the above embodiment determines whether an overvoltage has occurred in the high-voltage direct-mounted energy storage system based on multiple bus voltages and a first preset threshold value, as well as multiple time derivatives corresponding to the multiple bus voltages and a second preset threshold value, it further considers the frequency and variation trend of the overvoltage on the basis of the magnitude of the overvoltage, thereby more accurately determining whether an overvoltage has occurred in the high-voltage direct-mounted energy storage system.

[0024] In one embodiment, the method further comprises:

[0025] In the event of an overvoltage in the high-voltage direct-mounted energy storage system, the power unit is locked before the path between the power unit and the energy storage unit is disconnected.

[0026] In the above embodiment, when an overvoltage occurs in the high-voltage direct-mounted energy storage system, before disconnecting the path between the power unit and the energy storage unit, the power unit is locked, and only the path between the power unit and the energy storage unit is disconnected. The high-voltage direct-mounted energy storage system remains in a hot standby state, which facilitates the safe operation of the high-voltage direct-mounted energy storage system after the overvoltage is no longer present in the high-voltage direct-mounted energy storage system, thereby improving the stability of the high-voltage direct-mounted energy storage system.

[0027] In one embodiment, the method further comprises:

[0028] After disconnecting the path between the power unit and the energy storage unit, obtaining a second voltage on the bus side of the high-voltage direct-mounted energy storage system;

[0029] If it is determined based on the second voltage and the preset threshold that the high-voltage direct-mounted energy storage system does not have an overvoltage, the path between the power unit and the energy storage unit is opened.

[0030] In the above embodiment, after disconnecting the path between the power unit and the energy storage unit, it is necessary to determine whether the high-voltage direct-mounted energy storage system still has an overvoltage based on the second voltage, and to connect the path between the power unit and the energy storage unit when no overvoltage occurs in the high-voltage direct-mounted energy storage system. Therefore, after the overvoltage ends, the recovery logic can be executed to operate normally, thereby improving the stability of the high-voltage direct-mounted energy storage system.

[0031] In one embodiment, the step of conducting a path between the power unit and the energy storage unit includes:

[0032] Obtaining a first current voltage of a battery pack in the energy storage unit and a second current voltage of the power unit;

[0033] A path between the power unit and the energy storage unit is conducted according to the first current voltage and the second current voltage.

[0034] In the above embodiment, since the path between the power unit and the energy storage unit is conducted according to the first current voltage and the second current voltage, the problem of damage to the battery pack due to a large difference between the first current voltage of the battery pack in the energy storage unit and the second current voltage of the power unit when the path between the power unit and the energy storage unit is conducted is avoided, thereby improving the safety of conducting the path between the power unit and the energy storage unit.

[0035] In one embodiment, the step of conducting a path between the power unit and the energy storage unit according to the first current voltage and the second current voltage includes:

[0036] If the difference between the first current voltage and the second current voltage is not greater than a third preset threshold, the path between the power unit and the energy storage unit is opened.

[0037] The above embodiment avoids damaging the battery pack when the path between the power unit and the energy storage unit is opened, thereby improving the safety of the high-voltage direct-mounted energy storage system.

[0038] In one embodiment, the step of conducting a path between the power unit and the energy storage unit according to the first current voltage and the second current voltage includes:

[0039] If the difference between the first current voltage and the second current voltage is greater than the third preset threshold, the energy storage unit is connected in series with the voltage dividing resistor, and the path between the energy storage unit and the power unit is opened.

[0040] In the above embodiment, if the difference between the first current voltage and the second current voltage is greater than the third preset threshold, it indicates that the difference between the first current voltage and the second current voltage is large. In this case, when the path between the power unit and the energy storage unit is opened, there is a voltage difference between the battery pack in the power unit and the energy storage unit, which may damage the battery pack. Therefore, when the difference between the first current voltage and the second current voltage is greater than the third preset threshold, the control system connects the energy storage unit in series with the voltage divider resistor and then opens the path between the energy storage unit and the power unit, so that the voltage divider resistor plays the role of current limiting and voltage dividing, thereby improving the safety of the high-voltage direct-mounted energy storage system.

[0041] In one embodiment, the method further comprises:

[0042] After the path between the energy storage unit and the power unit is connected, obtaining a third current voltage of the battery pack in the energy storage unit and a fourth current voltage of the power unit;

[0043] If the difference between the third current voltage and the fourth current voltage is not greater than the third preset threshold, the path between the voltage dividing resistor and the energy storage unit is disconnected.

[0044] In the above embodiment, if the difference between the third current voltage and the fourth current voltage is not greater than the third preset threshold value, it means that after the voltage-dividing resistor is used to open the path between the energy storage unit and the power unit, the fourth current voltage of the capacitor in the power unit and the third current voltage of the battery pack in the energy storage unit are not much different. In this case, there is no need to use the voltage-dividing resistor to perform voltage division and current limiting. Therefore, when the difference between the third current voltage and the fourth current voltage is not greater than the third preset threshold value, the control system disconnects the path between the voltage-dividing resistor and the energy storage unit to ensure the operating efficiency of the high-voltage direct-mounted energy storage system.

[0045] In one embodiment, the method further comprises:

[0046] After the path between the power unit and the energy storage unit is opened, the power unit is unlocked.

[0047] In the above embodiment, after locking the power unit and disconnecting the path between the power unit and the energy storage unit, the control system can continue to conduct the path between the power unit and the energy storage unit and unlock the power unit, thereby restoring the operating state of the high-voltage direct-mounted energy storage system, thereby improving the stability of the high-voltage direct-mounted energy storage system.

[0048] In a second aspect, the present application also provides an overvoltage protection device for use in a high-voltage direct-mounted energy storage system, wherein the high-voltage direct-mounted energy storage system includes a power unit and an energy storage unit. The device includes:

[0049] A first acquisition module, configured to acquire a first voltage on the bus side of the high-voltage direct-mounted energy storage system;

[0050] a determination module, configured to determine whether an overvoltage occurs in the high-voltage direct-mounted energy storage system based on the first voltage and a preset threshold;

[0051] The first disconnection module is used to disconnect the path between the power unit and the energy storage unit when an overvoltage occurs in the high-voltage direct-mounted energy storage system.

[0052] In a third aspect, the present application further provides a computer device comprising a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of any of the above methods when executing the computer program.

[0053] In a fourth aspect, the present application further provides a computer-readable storage medium. The computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of any of the above methods.

[0054] In a fifth aspect, the present application further provides a computer program product, which includes a computer program that performs the steps of any of the above methods when executed by a processor.

[0055] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] FIG1 is a schematic flow chart of an overvoltage protection method according to an embodiment of the present application;

[0057] FIG2 is a diagram illustrating an application environment of an overvoltage protection method according to an embodiment of the present application;

[0058] FIG3 is a diagram illustrating an application environment of an overvoltage protection method according to an embodiment of the present application;

[0059] FIG4 is a schematic structural diagram of a half-bridge energy storage module;

[0060] FIG5 is a schematic structural diagram of a full-bridge energy storage module;

[0061] FIG6 is a schematic structural diagram of a half-bridge energy storage module provided in an embodiment of the present application;

[0062] FIG7 is a schematic diagram of a process for determining whether an overvoltage occurs in a high-voltage direct-mounted energy storage system according to an embodiment of the present application;

[0063] FIG8 is a schematic diagram of another process for determining whether an overvoltage occurs in a high-voltage direct-mounted energy storage system according to an embodiment of the present application;

[0064] FIG9 is a schematic diagram of the overall process of disconnecting the path between the power unit and the energy storage unit in this application;

[0065] FIG10 is a schematic diagram of a flow chart of a conductive path between a power unit and an energy storage unit according to an embodiment of the present application;

[0066] FIG11 is a schematic diagram of a flow chart of a conductive path between a power unit and an energy storage unit according to an embodiment of the present application;

[0067] FIG12 is a schematic structural diagram of a half-bridge energy storage module provided in an embodiment of the present application;

[0068] FIG13 is a schematic structural diagram of another half-bridge energy storage module provided in an embodiment of the present application;

[0069] FIG14 is a schematic diagram of a process for disconnecting a path between a voltage-dividing resistor and an energy storage unit according to an embodiment of the present application;

[0070] FIG15 is a schematic diagram of the overall process of conducting the path between the power unit and the energy storage unit in this application;

[0071] FIG16 is a structural block diagram of an overvoltage protection device according to an embodiment of the present application;

[0072] FIG17 is a diagram showing the internal structure of a computer device in an embodiment of the present application. DETAILED DESCRIPTION

[0073] In order to make the purpose, technical solutions and advantages of this application more clearly understood, the present application is further described in detail below 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.

[0074] High-voltage, direct-mounted energy storage systems are a new type of energy storage system. Each energy storage module in a high-voltage, direct-mounted energy storage system consists of a power unit and an energy storage unit, each of which includes a battery pack. Overvoltages can occur in high-voltage, direct-mounted energy storage systems due to external factors such as switching, lightning strikes, and load shedding, or internal factors such as ground faults, short circuits, and control failures in certain locations. In some operating conditions, high-voltage, direct-mounted energy storage systems cannot be disconnected from the grid and must ride through the fault. In other operating conditions, they can be disconnected from the grid, but the battery pack voltage stress during the disconnection process must be safe and reliable.

[0075] Because the transient overvoltage stress of the battery pack in the energy storage unit is very low and can basically only operate at the rated state, even if the overvoltage lasts for milliseconds, the overvoltage stress of the battery pack is less than 1.1pu. Other devices, such as capacitors and IGBTs in the power unit, have a relatively large overvoltage margin and are very low in cost compared to the battery pack. Therefore, when a condition such as a control failure occurs in a high-voltage direct-mounted energy storage system that cannot effectively limit the DC voltage, the battery pack in the energy storage unit should be quickly protected.

[0076] Closing the bypass switches of all power units would short-circuit the high-voltage direct-mounted energy storage system, rendering the bypass switches in the power units useless. Furthermore, when an overvoltage occurs in the high-voltage direct-mounted energy storage system, the system's actions—from overvoltage onset to fault detection, fault determination, and circuit breaker tripping—take at least a hundred to ten milliseconds. Consequently, the battery pack cannot recover from the overvoltage in a timely manner.

[0077] Therefore, battery packs are prone to failure under the influence of overvoltage, which can cause abnormalities in high-voltage direct-mounted energy storage systems. However, there is currently no overvoltage protection method for high-voltage direct-mounted energy storage systems. Therefore, how to implement overvoltage protection for high-voltage direct-mounted energy storage systems has become a key research topic for researchers in this field.

[0078] Based on the above considerations, the applicant has conducted in-depth research and proposed a method for overvoltage protection for high-voltage direct-mounted energy storage systems. The method includes: obtaining a first voltage on the bus side of the high-voltage direct-mounted energy storage system, and then determining whether the high-voltage direct-mounted energy storage system has an overvoltage based on the first voltage and a preset threshold value, thereby disconnecting the path between the power unit and the energy storage unit when the high-voltage direct-mounted energy storage system has an overvoltage. This method can temporarily remove the energy storage unit from the high-voltage direct-mounted energy storage system in a timely manner when the high-voltage direct-mounted energy storage system generates an overvoltage, that is, it can temporarily remove the battery pack in the energy storage unit from the high-voltage direct-mounted energy storage system in a timely manner. Therefore, it solves the problem in current usage scenarios that when the high-voltage direct-mounted energy storage system generates an overvoltage, the battery pack fails under the action of the overvoltage and causes the high-voltage direct-mounted energy storage system to be abnormal, thereby improving the operating stability and safety of the high-voltage direct-mounted energy storage system. Moreover, since the present application only disconnects the path between the power unit and the energy storage unit, the battery pack in the energy storage unit can be temporarily removed from the high-voltage direct-mounted energy storage system in a timely manner. This is a convenient, fast-acting, and minimally modified overvoltage protection method.

[0079] The overvoltage protection method of the present application will be introduced below. Please refer to Figure 1, which is a flow chart of the overvoltage protection method in an embodiment of the present application. The method can be applied to a high-voltage direct-mounted energy storage system.

[0080] In order to more clearly explain the overvoltage protection method in the present application, it is illustrated here with reference to Figures 2 to 5. Figures 2 and 3 are application environment diagrams of the overvoltage protection method in the embodiment of the present application. The access control method provided in the embodiment of the present application can be applied to the high-voltage direct-mounted energy storage system as shown in Figures 2 and 3. Figure 2 shows a system architecture diagram of a DC high-voltage direct-mounted energy storage system, and Figure 3 shows a system architecture diagram of an AC high-voltage direct-mounted energy storage system. Figure 4 is a structural diagram of a half-bridge energy storage module, and Figure 5 is a structural diagram of a full-bridge energy storage module.

[0081] As shown in Figure 2, a DC high-voltage direct-mounted energy storage system can be configured in a high-voltage DC transmission line, that is, between the positive DC bus and the negative DC bus. The DC high-voltage direct-mounted energy storage system includes an isolation switch, a reactor, at least one energy storage module SM, and a control system. Where n is an integer greater than or equal to 1, and the total number of energy storage modules n can be configured according to the voltage level of the transmission system. SM n In Figure 3, similarly, in an AC high-voltage direct-mounted energy storage system, each phase of the AC busbar is connected in series with a cascaded energy storage module. The number of cascaded energy storage modules can still be configured according to the voltage level and capacity of the AC high-voltage direct-mounted energy storage system, which will not be further described here.

[0082] In conjunction with Figures 4 and 5, the energy storage module in Figure 2 or Figure 3 includes a power unit and an energy storage unit, that is, the high-voltage direct-mounted energy storage system includes a power unit and an energy storage unit. Specifically, the power unit 401 in Figure 4 is a half-bridge type, and the power unit 401 includes a bypass switch 403, a fully controlled switch 404, a fully controlled switch 405, a capacitor 406, and a voltage equalizing resistor 407. The energy storage unit 402 includes a battery pack 408. The power unit 501 in Figure 5 is a full-bridge type, and the power unit 501 includes a bypass switch 503, a fully controlled switch 504, a fully controlled switch 505, a fully controlled switch 506, a fully controlled switch 507, a capacitor 508, and a voltage equalizing resistor 509. The energy storage unit 502 includes a battery pack 510. That is to say, in the topology of the high-voltage direct-mounted energy storage system, the full-bridge or half-bridge power unit is connected in parallel with the energy storage unit, and the energy storage unit includes a battery pack. It should be noted that, in addition to the structures shown in FIG. 4 and FIG. 5 , the power unit may also be in other forms, such as a quasi-full-bridge type, which is not limited in this embodiment.

[0083] Continuing with Figure 2, the isolation switch controls whether the high-voltage direct-mounted energy storage system is connected to the transmission line, and the reactor suppresses harmonics and short-circuit currents. Furthermore, in conjunction with Figures 2 and 3, the control system controls and protects the high-voltage direct-mounted energy storage system. The control system may include at least one of a digital signal processor (DSP) and a field-programmable gate array (FPGA).

[0084] Taking the half-bridge energy storage module in Figure 4 as an example, when the high-voltage direct-mount energy storage system is operating normally, the control system controls bypass switch 404 to open, the insulated gate bipolar transistors (IGBTs) in fully-controlled switches 404 and 405 to disconnect, and the diodes in fully-controlled switches 404 and 405 to conduct, thereby unlocking power unit 401 and connecting battery pack 408 to the high-voltage direct-mount energy storage system. The same principle applies to Figure 4 and will not be repeated here.

[0085] Please continue to refer to FIG1 . In one embodiment, as shown in FIG1 , the overvoltage protection method in this application includes the following steps:

[0086] S101, obtaining a first voltage on the bus side of a high-voltage direct-mounted energy storage system.

[0087] Overvoltage in a high-voltage direct-mounted energy storage system will occur on the bus side. Therefore, in this embodiment, please refer to Figures 2 and 3. The control system obtains the first voltage on the bus side of the high-voltage direct-mounted energy storage system. For example, for the DC high-voltage direct-mounted energy storage system in Figure 2, the control system obtains the first voltage of the DC bus. For the AC high-voltage direct-mounted energy storage system in Figure 3, the control system obtains the first voltage of the AC bus.

[0088] The first bus-side voltage includes at least one instantaneous bus-side voltage, such as first bus-side voltage 1 at time 1 and first bus-side voltage 2 at time 2. The control system may obtain the first bus-side voltage of the high-voltage direct-mounted energy storage system by: a voltage monitoring device establishes communication with the control system, the voltage monitoring device obtains the first bus-side voltage, and the voltage monitoring device sends the obtained first voltage to the control system, thereby obtaining the first bus-side voltage.

[0089] S102: Determine whether an overvoltage occurs in the high-voltage direct-mounted energy storage system based on the first voltage and a preset threshold.

[0090] In this embodiment, after obtaining the first bus-side voltage, the control system can determine whether the high-voltage direct-mounted energy storage system has an overvoltage based on the first voltage and a preset threshold. The preset threshold is a threshold set based on the overvoltage stress of the high-voltage direct-mounted energy storage system.

[0091] For example, the preset thresholds include a first preset threshold of 1.3 times the standard voltage, where the standard voltage is also the system voltage of the high-voltage direct-mounted energy storage system, for example, 2000 volts. Of course, the first preset threshold may also use other per-unit values, and this embodiment is not limited thereto. The control system may obtain the first voltage on the bus side in chronological order, and then the control system obtains the first voltage at time 1, the first voltage at time 2, and so on. When the first voltage at time 2 is greater than the first preset threshold, the control system determines that an overvoltage has occurred in the high-voltage direct-mounted energy storage system.

[0092] Alternatively, the preset threshold includes a second preset threshold, for example, the second preset threshold is 100. The control system may obtain the first voltage on the bus side in chronological order and determine the time derivative of the first voltage with respect to time. The control system then obtains the time derivative of the first voltage at time 1, the time derivative of the first voltage at time 2, and so on. When the time derivative of the first voltage at time 2 is greater than the second preset threshold, the control system determines that an overvoltage has occurred in the high-voltage direct-mounted energy storage system.

[0093] Of course, the control system may also determine whether the high-voltage direct-mounted energy storage system has an overvoltage according to the first voltage and the preset threshold value in other ways, and this embodiment does not impose any limitation thereto.

[0094] S103 , when an overvoltage occurs in the high-voltage direct-mounted energy storage system, disconnect the path between the power unit and the energy storage unit.

[0095] In this embodiment, the control system disconnects the path between the power unit and the energy storage unit if it determines that the high-voltage direct-mounted energy storage system has an overvoltage. It is understood that the control system may not take any action if it determines that the high-voltage direct-mounted energy storage system has not an overvoltage.

[0096] One way to disconnect the path between the power unit and the energy storage unit is to add a solid-state switch on the energy storage unit side. Please refer to Figure 6, which is a structural diagram of the half-bridge energy storage module provided in an embodiment of the present application. Taking the half-bridge energy storage module as an example, a solid-state switch 609 is added to the path between the power unit 601 and the energy storage unit 602. During normal operation, the bypass switch 603 is disconnected, the solid-state switch 609 is closed, the IGBTs in the full-control switch 604 and the full-control switch 605 are both disconnected, and the diodes in the full-control switch 604 and the full-control switch 605 are both turned on, so that the power unit 601 is unlocked and the battery pack 608 is connected to the high-voltage direct-mounted energy storage system.

[0097] When the control system determines that the high-voltage direct-mounted energy storage system has an overvoltage, it can disconnect solid-state switch 609 to cut off the path between power unit 601 and energy storage unit 602. Solid-state switch 609 can be an IGBT, an integrated gate-commutated thyristor (IGCT), or other component, and this embodiment does not limit this. The principles of a full-bridge energy storage module are similar and will not be further described here.

[0098] In conjunction with Figure 6, the present application adds a solid-state switch on the energy storage unit side, that is, after making minor changes to the circuit of the current high-voltage direct-mounted energy storage system, it is possible to promptly disconnect the path between the power unit and the energy storage unit when an overvoltage occurs in the high-voltage direct-mounted energy storage system. Therefore, the overvoltage protection method provided by the present application not only responds quickly but also has low cost, and can effectively protect the high-voltage direct-mounted energy storage system.

[0099] The overvoltage protection method provided in this embodiment is applied to a high-voltage direct-mounted energy storage system, which includes a power unit and an energy storage unit. The method first obtains a first voltage on the bus side of the high-voltage direct-mounted energy storage system, and then determines whether the high-voltage direct-mounted energy storage system has an overvoltage based on the first voltage and a preset threshold. In this way, if the high-voltage direct-mounted energy storage system has an overvoltage, the path between the power unit and the energy storage unit is disconnected. Because this embodiment can judge the overvoltage state of the high-voltage direct-mounted energy storage system based on the first voltage on the bus side of the high-voltage direct-mounted energy storage system and the preset threshold, and then determine whether the high-voltage direct-mounted energy storage system has an overvoltage, and further, if it is determined that the high-voltage direct-mounted energy storage system has an overvoltage, the embodiment can disconnect the path between the power unit and the energy storage unit when it is determined that the high-voltage direct-mounted energy storage system has an overvoltage, thus, the embodiment can timely temporarily remove the energy storage unit from the high-voltage direct-mounted energy storage system when the high-voltage direct-mounted energy storage system has an overvoltage, that is, timely temporarily remove the battery pack in the energy storage unit from the high-voltage direct-mounted energy storage system. Therefore, the method provided in this embodiment solves the problem that when a high-voltage direct-mounted energy storage system generates an overvoltage, the battery pack in the energy storage unit has a very low transient overvoltage stress, and the battery pack fails under the action of overvoltage and causes an abnormality in the high-voltage direct-mounted energy storage system. It provides a method for overvoltage protection for the high-voltage direct-mounted energy storage system, thereby improving the operational stability and safety of the high-voltage direct-mounted energy storage system. In addition, since the present application does not require major changes to the circuit, only the path between the power unit and the energy storage unit is disconnected, and the battery pack in the energy storage unit can be temporarily removed from the high-voltage direct-mounted energy storage system in a timely manner. Therefore, the overvoltage protection method provided by the present application is a convenient, fast-acting, and small-change method.

[0100] Optionally, the above-mentioned S102, determining whether the high-voltage direct-mounted energy storage system has an overvoltage according to the first voltage and a preset threshold, can be implemented as follows:

[0101] If the first voltage includes multiple bus voltages collected within a preset time period, it is determined whether the high-voltage direct-mounted energy storage system has an overvoltage based on the multiple bus voltages and a preset threshold.

[0102] In this embodiment, to improve the accuracy of determining whether a high-voltage, direct-mounted energy storage system has experienced overvoltage, the first voltage includes multiple bus voltages collected over a preset time period. The control system then determines whether the high-voltage, direct-mounted energy storage system has experienced overvoltage based on the multiple bus voltages and a preset threshold. The preset time period can be set as needed, for example, to 1 millisecond.

[0103] For example, assuming the preset time length is 1 millisecond, the control system obtains 50 first voltages on the bus side of the high-voltage direct-mounted energy storage system within 1 millisecond. The control system can compare the above 50 first voltages with the first preset threshold. When 48 of the 50 first voltages are greater than the first preset threshold, the control system determines that an overvoltage has occurred in the high-voltage direct-mounted energy storage system.

[0104] Alternatively, after the control system obtains 50 first bus-side voltages of the high-voltage direct-mounted energy storage system within 1 millisecond, the control system may average the 50 first voltages and compare the average with a first preset threshold. When the average of the 50 first voltages is greater than the first preset threshold, the control system determines that an overvoltage has occurred in the high-voltage direct-mounted energy storage system. This embodiment is not limited to this.

[0105] In this embodiment, if the first voltage includes multiple bus voltages collected within a preset time period, then the determination of whether the high-voltage direct-mounted energy storage system has experienced an overvoltage is made based on the multiple bus voltages and a preset threshold. This avoids the problem of low accuracy when determining whether the high-voltage direct-mounted energy storage system has experienced an overvoltage based on a single bus voltage and a preset threshold. Furthermore, by determining whether the high-voltage direct-mounted energy storage system has experienced an overvoltage based on multiple bus voltages collected within a preset time period, disconnecting the path between the power unit and the energy storage unit in the event of an overvoltage in the high-voltage direct-mounted energy storage system prevents frequent changes in the operating state of the high-voltage direct-mounted energy storage system, thereby further improving the safety and stability of the high-voltage direct-mounted energy storage system.

[0106] FIG7 is a flow chart of a method for determining whether a high-voltage direct-mounted energy storage system has an overvoltage according to an embodiment of the present application. Referring to FIG7 , this embodiment relates to an optional implementation method for determining whether a high-voltage direct-mounted energy storage system has an overvoltage. Based on the above embodiment, the above method for determining whether a high-voltage direct-mounted energy storage system has an overvoltage according to multiple bus voltages and preset thresholds includes the following steps:

[0107] S701: When multiple bus voltages are greater than a first preset threshold, determine that an overvoltage occurs in the high-voltage direct-mounted energy storage system.

[0108] In this embodiment, assuming that the preset duration is 1 millisecond, the control system obtains 50 first voltages on the bus side of the high-voltage direct-mounted energy storage system within 1 millisecond. When all 50 first voltages are greater than the first preset threshold, it is determined that an overvoltage has occurred in the high-voltage direct-mounted energy storage system. Since the preset duration can be changed according to demand, in other words, the control system determines that an overvoltage has occurred in the high-voltage direct-mounted energy storage system when N (N is an integer greater than 1) consecutive bus voltages are greater than the first preset threshold. The first preset threshold is a threshold set according to the maximum tolerable overvoltage of the high-voltage direct-mounted energy storage system, for example, 1.3 times the standard voltage.

[0109] S702: When the voltages of the multiple buses are not greater than a first preset threshold, determine that the high-voltage direct-mounted energy storage system does not have an overvoltage.

[0110] In this embodiment, similar to S701, the control system determines that the high-voltage direct-mounted energy storage system has an overvoltage if N consecutive bus voltages (N is an integer greater than 1) are no greater than a first preset threshold. For example, assuming the preset duration is 1 millisecond, and the control system obtains 50 first bus-side voltages of the high-voltage direct-mounted energy storage system within 1 millisecond, then if none of the 50 first voltages are greater than the first preset threshold, the high-voltage direct-mounted energy storage system is determined to be free of overvoltage.

[0111] This embodiment determines that an overvoltage has occurred in the high-voltage direct-mounted energy storage system when multiple bus voltages are all greater than a first preset threshold value, and determines that no overvoltage has occurred in the high-voltage direct-mounted energy storage system when multiple bus voltages are not greater than the first preset threshold value. Because the determination of whether an overvoltage has occurred in the high-voltage direct-mounted energy storage system can be made based on the comparison results of multiple bus voltages with the first preset threshold value, this improves the accuracy of determining an overvoltage in the high-voltage direct-mounted energy storage system and also increases the speed of determining an overvoltage in the high-voltage direct-mounted energy storage system. Consequently, if an overvoltage occurs in the high-voltage direct-mounted energy storage system, the control system can promptly disconnect the path between the power unit and the energy storage unit.

[0112] FIG8 is a flow chart of another method for determining whether a high-voltage direct-mounted energy storage system has an overvoltage according to an embodiment of the present application. Referring to FIG8 , this embodiment relates to an optional implementation method for determining whether a high-voltage direct-mounted energy storage system has an overvoltage. Based on the above embodiment, the above method for determining whether a high-voltage direct-mounted energy storage system has an overvoltage according to multiple bus voltages and preset thresholds may further include the following steps:

[0113] S801, obtaining a plurality of time derivatives of a plurality of bus voltages after time derivatives are obtained.

[0114] In this embodiment, after obtaining multiple bus voltages, the control system further obtains multiple time derivatives of the multiple bus voltages after derivation with respect to time. Specifically, the control system can obtain the time derivative of the bus voltage du(t+1) / dt according to the following formula (1).

[0115]

[0116] Wherein, du(t+1) / dt represents the time derivative of the t+1th bus voltage within the preset time length, u(t+1) represents the t+1th bus voltage within the preset time length, u(t) represents the tth bus voltage within the preset time length, T is the time difference between t+1 and t-1, and t is an integer greater than or equal to 1.

[0117] S802 : When multiple bus voltages are greater than a first preset threshold and multiple time derivatives are greater than a second preset threshold, determine that an overvoltage occurs in the high-voltage direct-mounted energy storage system.

[0118] In this embodiment, after the control system determines multiple time derivatives of multiple bus voltages derived with respect to time, when the multiple bus voltages are all greater than the first preset threshold value, and the multiple time derivatives are all greater than the second preset threshold value, the control system determines that the high-voltage direct-mounted energy storage system has an overvoltage. In other words, the control system determines that the high-voltage direct-mounted energy storage system has an overvoltage when N consecutive bus voltages are greater than the first preset threshold value, and M (M is an integer greater than 1) consecutive time derivatives of the bus voltage are greater than the second preset threshold value. Wherein, the number of M and N can be the same or different, and the second preset threshold value is a threshold value set according to the frequency of the overvoltage of the high-voltage direct-mounted energy storage system, and the second preset threshold value is generally a number greater than 50. For example, if the frequency of the operating overvoltage is usually above 100 Hz, the second preset threshold value can be 100.

[0119] S803: When the multiple bus voltages are not greater than the first preset threshold and the multiple time derivatives are not greater than the second preset threshold, determine that the high-voltage direct-mounted energy storage system does not have an overvoltage.

[0120] In this embodiment, the principle is the same as that of S802. The control system determines that the high-voltage direct-mounted energy storage system is not overvoltage when N consecutive bus voltages are not greater than a first preset threshold and M (M is an integer greater than 1) consecutive bus voltage time derivatives are not greater than a second preset threshold.

[0121] This embodiment obtains multiple time derivatives of multiple bus voltages derived with respect to time. If all of the multiple bus voltages are greater than a first preset threshold value and all of the multiple time derivatives are greater than a second preset threshold value, it is determined that the high-voltage direct-mounted energy storage system has experienced an overvoltage. If all of the multiple bus voltages are not greater than the first preset threshold value and all of the multiple time derivatives are not greater than the second preset threshold value, it is determined that the high-voltage direct-mounted energy storage system has not experienced an overvoltage. Because the determination of whether the high-voltage direct-mounted energy storage system has experienced an overvoltage is based on the multiple bus voltages and the first preset threshold value, as well as the multiple time derivatives and second preset threshold values ​​corresponding to the multiple bus voltages, the frequency and changing trend of the overvoltage are further considered in addition to the magnitude of the overvoltage, thereby more accurately determining whether the high-voltage direct-mounted energy storage system has experienced an overvoltage.

[0122] Optionally, the above overvoltage protection method further includes:

[0123] In the event of overvoltage in the high-voltage direct-mounted energy storage system, the power unit is locked before the path between the power unit and the energy storage unit is disconnected.

[0124] In this embodiment, referring to FIG6 , taking a half-bridge energy storage module as an example, when the control system determines that the high-voltage direct-mounted energy storage system has an overvoltage, the control system controls the IGBTs in fully-controlled switches 604 and 605 to conduct evenly and controls the diodes in fully-controlled switches 604 and 605 to be disconnected before disconnecting solid-state switch 609 to cut off the path between power unit 601 and energy storage unit 602. This causes power unit 601 to be locked, and capacitor 606 in power unit 601 supports the voltage of the high-voltage direct-mounted energy storage system. Voltage-sharing resistor 607 is used to balance the current and voltage in this situation. In other words, after locking power unit 601, the high-voltage direct-mounted energy storage system is not completely off-grid and remains in a hot standby state.

[0125] In the present embodiment, when an overvoltage occurs in the high-voltage direct-mounted energy storage system, before disconnecting the path between the power unit and the energy storage unit, the power unit is locked, and only the path between the power unit and the energy storage unit is disconnected. The high-voltage direct-mounted energy storage system remains in a hot standby state, facilitating safe operation of the high-voltage direct-mounted energy storage system after the overvoltage is eliminated, thereby improving the stability of the high-voltage direct-mounted energy storage system.

[0126] In order to more clearly explain the overvoltage protection method in this application, it is illustrated in conjunction with Figure 9. Figure 9 is a schematic diagram of the overall process of disconnecting the path between the power unit and the energy storage unit in this application. The control system obtains multiple bus voltages collected within a preset time period. If the multiple bus voltages are all greater than a first preset threshold, it is determined that the high-voltage direct-mounted energy storage system has an overvoltage. Otherwise, it is determined that the high-voltage direct-mounted energy storage system has not an overvoltage. Alternatively, the control system obtains multiple bus voltages collected within a preset time period and multiple time derivatives of the multiple bus voltages after time derivatives are taken. If the multiple bus voltages are all greater than a first preset threshold and the multiple time derivatives are all greater than a second preset threshold, it is determined that the high-voltage direct-mounted energy storage system has an overvoltage. Otherwise, it is determined that the high-voltage direct-mounted energy storage system has not an overvoltage. Furthermore, the control system does not take any action if the high-voltage direct-mounted energy storage system has not an overvoltage. If the high-voltage direct-mounted energy storage system has an overvoltage, it locks the power unit and disconnects the path between the power unit and the energy storage unit.

[0127] FIG10 is a flow chart of a method for conducting a path between a power unit and an energy storage unit according to an embodiment of the present application. Referring to FIG10 , this embodiment relates to an optional implementation method for conducting a path between a power unit and an energy storage unit. Based on the above embodiment, the above overvoltage protection method further includes the following steps:

[0128] S1001: After disconnecting the path between the power unit and the energy storage unit, obtain a second voltage on the bus side of the high-voltage direct-mounted energy storage system.

[0129] In this embodiment, after the control system disconnects the path between the power unit and the energy storage unit, it obtains a second voltage on the bus side of the high-voltage direct-mounted energy storage system. This second voltage still includes at least one instantaneous bus side voltage, such as second bus side voltage 1 at time 4 and second bus side voltage 2 at time 5.

[0130] S1002: If it is determined based on the second voltage and the preset threshold that the high-voltage direct-mounted energy storage system does not have an overvoltage, then a path between the power unit and the energy storage unit is opened.

[0131] In this embodiment, the method for determining that the high-voltage direct-mounted energy storage system has not experienced overvoltage based on the second voltage and the preset threshold is the same as the principle of the method for determining that the high-voltage direct-mounted energy storage system has not experienced overvoltage based on the first voltage and the preset threshold, and will not be repeated here. For example, the control system obtains 50 second voltages on the bus side of the high-voltage direct-mounted energy storage system within 1 millisecond. The control system can compare the above 50 second voltages with the first preset threshold. If none of the 50 second voltages are greater than the first preset threshold, it is determined that the high-voltage direct-mounted energy storage system has not experienced overvoltage. Alternatively, the control system obtains 50 second voltages on the bus side of the high-voltage direct-mounted energy storage system within 1 millisecond and takes the time derivative of the above 50 second voltages to determine the corresponding 50 time derivatives. If the 50 second voltages are not greater than the first preset threshold, and the time derivatives corresponding to the 50 second voltages are all less than the second preset threshold, it is determined that the high-voltage direct-mounted energy storage system has not experienced overvoltage. It should be noted that the second voltage may also include multiple bus voltages collected within a preset time period, and the preset time period may be the same as or different from the preset time period set when obtaining the first voltage.

[0132] Furthermore, if the high-voltage direct-mounted energy storage system is determined to be free of overvoltage based on the second voltage and the preset threshold, the control system opens the path between the power unit and the energy storage unit. Using Figure 6 as an example, the control system controls solid-state switch 609 to close, thereby opening the path between the power unit and the energy storage unit. Of course, the control system may also open the path between the power unit and the energy storage unit using other methods, and this embodiment is not limiting.

[0133] After disconnecting the path between the power unit and the energy storage unit, this embodiment obtains a second voltage on the busbar side of the high-voltage direct-mounted energy storage system. If, based on the second voltage and a preset threshold, it is determined that the high-voltage direct-mounted energy storage system has not experienced an overvoltage, the path between the power unit and the energy storage unit is opened. Since, after disconnecting the path between the power unit and the energy storage unit, it is necessary to determine whether the high-voltage direct-mounted energy storage system still has an overvoltage based on the second voltage, and to open the path between the power unit and the energy storage unit if the high-voltage direct-mounted energy storage system has not experienced an overvoltage, the restoration logic can be executed to operate normally after the overvoltage ends, thereby improving the stability of the high-voltage direct-mounted energy storage system.

[0134] FIG11 is a flow chart of a method for conducting a path between a power unit and an energy storage unit in an embodiment of the present application. Referring to FIG11 , this embodiment relates to an optional implementation method for conducting a path between a power unit and an energy storage unit. Based on the above embodiment, the above-mentioned method for conducting a path between a power unit and an energy storage unit includes the following steps:

[0135] S1101, obtaining a first current voltage of a battery pack in an energy storage unit and a second current voltage of a power unit.

[0136] In this embodiment, before the path between the power unit and the energy storage unit is established, the control system obtains the first current voltage of the battery pack in the energy storage unit and the second current voltage of the power unit. Taking Figure 4 as an example, the second current voltage of power unit 401 is also the second current voltage of capacitor 406 in power unit 401. Obtaining the first current voltage of battery pack 408 in energy storage unit 402 and the second current voltage of power unit 401 is equivalent to the control system obtaining the first current voltage of battery pack 408 and the second current voltage of capacitor 406 in power unit 401. The same applies to Figure 5 and will not be repeated here.

[0137] S1102 : Conducting a path between the power unit and the energy storage unit according to the first current voltage and the second current voltage.

[0138] In this embodiment, the control system conducts the path between the power unit and the energy storage unit based on the first current voltage and the second current voltage. In conjunction with Figure 4, when the path between power unit 401 and energy storage unit 402 is conducted, it also means that the battery pack 408 is connected to the high-voltage direct-mounted energy storage system. In this case, the battery pack 408 in the energy storage unit 402 and the capacitor 406 in the power unit form a circuit. If the second current voltage of the capacitor 406 in the power unit 401 differs too much from the first current voltage of the battery pack 408 in the energy storage unit 402, the path between the power unit 401 and the energy storage unit 402 will be damaged. Therefore, the control system needs to conduct the path between the power unit and the energy storage unit based on the first current voltage and the second current voltage. For example, the control system conducts the path between the power unit and the energy storage unit when the ratio of the first current voltage to the second current voltage is close to 1; or, the control system conducts the path between the power unit and the energy storage unit when the difference between the first current voltage and the second current voltage is equal to 0.

[0139] This embodiment obtains the first current voltage of the battery pack in the energy storage unit and the second current voltage of the power unit, and conducts a path between the power unit and the energy storage unit based on the first current voltage and the second current voltage. Because the path between the power unit and the energy storage unit is conducted based on the first current voltage and the second current voltage, this avoids the problem of damage to the battery pack caused by a large difference between the first current voltage of the battery pack in the energy storage unit and the second current voltage of the power unit when conducting the path between the power unit and the energy storage unit, thereby improving safety when conducting the path between the power unit and the energy storage unit.

[0140] Optionally, the above-mentioned S1102, conducting the path between the power unit and the energy storage unit according to the first current voltage and the second current voltage, can be implemented in the following manner:

[0141] If the difference between the first current voltage and the second current voltage is not greater than a third preset threshold, the path between the power unit and the energy storage unit is turned on.

[0142] In this embodiment, if the difference between the first current voltage and the second current voltage is not greater than the third preset threshold, it indicates that the difference between the first current voltage and the second current voltage is not significant. In this case, opening the path between the power unit and the energy storage unit will not damage the battery pack. Therefore, the control system will open the path between the power unit and the energy storage unit if the difference between the first current voltage and the second current voltage is not greater than the third preset threshold. For example, with reference to FIG6 , the control system closes solid-state switch 609. The third preset threshold can be set based on demand and experience, for example, a value below 100 volts, such as 10 volts or 20 volts.

[0143] In this embodiment, if the difference between the first current voltage and the second current voltage is not greater than the third preset threshold, the path between the power unit and the energy storage unit is opened, thereby avoiding damage to the battery pack when the path between the power unit and the energy storage unit is opened, thereby improving the safety of the high-voltage direct-mounted energy storage system.

[0144] Optionally, the above-mentioned S1102, conducting the path between the power unit and the energy storage unit according to the first current voltage and the second current voltage, can also be implemented in the following manner:

[0145] If the difference between the first current voltage and the second current voltage is greater than a third preset threshold, the energy storage unit is connected in series with the voltage dividing resistor to open a path between the energy storage unit and the power unit.

[0146] In this embodiment, if the difference between the first current voltage and the second current voltage is greater than a third preset threshold, this indicates a significant difference between the first current voltage and the second current voltage. In this case, when the path between the power unit and the energy storage unit is opened, a voltage difference exists between the power unit and the battery pack in the energy storage unit, potentially damaging the battery pack. Therefore, when the difference between the first current voltage and the second current voltage is greater than the third preset threshold, the control system connects the energy storage unit in series with a voltage divider resistor and then opens the path between the energy storage unit and the power unit, allowing the voltage divider resistor to act as a current limiter and voltage divider, thereby improving the safety of the high-voltage direct-mounted energy storage system.

[0147] FIG12 is a schematic diagram of the structure of a half-bridge energy storage module provided in an embodiment of the present application. One possible implementation method is to add a solid-state switch 1209, a solid-state switch 1210, and a voltage divider resistor 1211 to the high-voltage direct-mounted energy storage system. If the difference between the first current voltage and the second current voltage is greater than a third preset threshold, the control system closes the solid-state switch 1210. Since the solid-state switch 1210 is connected in series with the voltage divider resistor 1211, closing the solid-state switch 1210 means that the control system connects the energy storage unit and the voltage divider resistor in series, thereby opening the path between the energy storage unit and the power unit.

[0148] FIG13 is a schematic diagram of the structure of another half-bridge energy storage module provided in an embodiment of the present application. Another possible implementation method is to add a solid-state switch 1309, a solid-state switch 1310, and a voltage-dividing resistor 1311 to the high-voltage direct-mounted energy storage system. If the difference between the first current voltage and the second current voltage is greater than a third preset threshold, the control system closes the solid-state switch 1309. Since the solid-state switch 1309 is connected in series with the voltage-dividing resistor 1311, closing the solid-state switch 1309 means that the control system connects the energy storage unit and the voltage-dividing resistor in series, thereby opening the path between the energy storage unit and the power unit.

[0149] It should be noted that solid-state switches 1209 and 1210 in FIG. 12 , and solid-state switches 1309 and 1311 in FIG. 12 , may also be IGBTs, integrated gate-commutated thyristors (IGCTs), and other components, without limitation in this embodiment. The same applies to the full-bridge energy storage module and will not be further described here.

[0150] In this embodiment, if the difference between the first current voltage and the second current voltage is greater than a third preset threshold, the energy storage unit is connected in series with the voltage-dividing resistor, and then the path between the energy storage unit and the power unit is opened. Since the energy storage unit can be connected in series with the voltage-dividing resistor when there is a large difference between the first current voltage and the second current voltage, and then the path between the energy storage unit and the power unit is opened, damage to the battery pack during conduction is avoided, thereby improving the safety of the high-voltage direct-mounted energy storage system.

[0151] FIG14 is a flow chart of disconnecting the path between the voltage divider resistor and the energy storage unit according to an embodiment of the present application. Referring to FIG14 , this embodiment relates to an optional implementation method of disconnecting the path between the voltage divider resistor and the energy storage unit. Based on the above embodiment, the above overvoltage protection method further includes the following steps:

[0152] S1401: Obtain a third current voltage of the battery pack in the energy storage unit and a fourth current voltage of the power unit.

[0153] In this embodiment, after the path between the energy storage unit and the power unit is opened, the control system obtains the third current voltage of the battery pack in the energy storage unit and the fourth current voltage of the power unit. Taking Figure 12 as an example, after the path between the energy storage unit and the power unit is opened via solid-state switch 1210, the control system obtains the third current voltage of battery pack 1208 and the fourth current voltage of power unit 1201, i.e., the fourth current voltage of capacitor 1206 in power unit 1201.

[0154] S1402: If the difference between the third current voltage and the fourth current voltage is not greater than a third preset threshold, disconnecting the path between the voltage-dividing resistor and the energy storage unit.

[0155] In this embodiment, if the difference between the third current voltage and the fourth current voltage is not greater than the third preset threshold value, it means that after the voltage-dividing resistor is used to conduct the path between the energy storage unit and the power unit, the fourth current voltage of the capacitor in the power unit and the third current voltage of the battery pack in the energy storage unit are not much different. In this case, there is no need to perform voltage division and current limiting through the voltage-dividing resistor. Therefore, when the difference between the third current voltage and the fourth current voltage is not greater than the third preset threshold value, the control system disconnects the path between the voltage-dividing resistor and the energy storage unit to ensure the operating efficiency of the high-voltage direct-mounted energy storage system.

[0156] In conjunction with Figure 12, one way to disconnect the path between the voltage divider resistor and the energy storage unit is: if the difference between the third current voltage and the fourth current voltage is not greater than the third preset threshold, the control system disconnects the solid-state switch 1210 and closes the solid-state switch 1209, thereby disconnecting the path between the voltage divider resistor and the energy storage unit.

[0157] In conjunction with Figure 13, another way to disconnect the path between the voltage-dividing resistor and the energy storage unit is: if the difference between the third current voltage and the fourth current voltage is not greater than the third preset threshold, the control system continues to close the solid-state switch 1311 on the basis of closing the solid-state switch 1309, so that the voltage-dividing resistor 1311 is short-circuited, thereby disconnecting the path between the voltage-dividing resistor and the energy storage unit.

[0158] After the path between the energy storage unit and the power unit is connected, this embodiment obtains a third current voltage of the battery pack in the energy storage unit and a fourth current voltage of the power unit. If the difference between the third current voltage and the fourth current voltage is not greater than a third preset threshold, the path between the voltage divider resistor and the energy storage unit is disconnected. Since the voltage divider resistor is disconnected when the difference between the third current voltage and the fourth current voltage is not large, voltage division and current limiting are no longer performed, thereby improving the operating efficiency of the energy storage unit, that is, improving the operating efficiency of the high-voltage direct-mounted energy storage system.

[0159] Optionally, the above overvoltage protection method further includes the following steps:

[0160] After the path between the power unit and the energy storage unit is established, the power unit is unlocked.

[0161] In this embodiment, please continue to refer to Figure 12. In Figure 12, the high-voltage direct-mounted energy storage system is normally closed in solid-state switch 1209. If the control system determines that an overvoltage has occurred in the high-voltage direct-mounted energy storage system, the control system opens solid-state switch 1209 to disconnect the path between power unit 1201 and energy storage unit 1202.

[0162] After disconnecting the path between power unit 1201 and energy storage unit 1202, if the control system determines, based on the second voltage and the preset threshold, that the high-voltage direct-mounted energy storage system is no longer overvoltage, the control system then connects the path between power unit 1201 and energy storage unit 1202. After connecting the path between the power unit and the energy storage unit, the control system controls the IGBTs in full-controlled switches 1204 and 1205 to be disconnected and the diodes in full-controlled switches 1204 and 1205 to be conductive, thereby unlocking power unit 601 and restoring the operating state of the high-voltage direct-mounted energy storage system. The same applies to the full-bridge energy storage module and will not be further described here.

[0163] In this embodiment, after the path between the power unit and the energy storage unit is opened, the power unit is unlocked. Since the control system can continue to open the path between the power unit and the energy storage unit and unlock the power unit after locking the power unit and disconnecting the path between the power unit and the energy storage unit, restoring the operating state of the high-voltage direct-mounted energy storage system, the stability of the high-voltage direct-mounted energy storage system is improved.

[0164] FIG15 is a schematic diagram of the overall process of conducting the path between the power unit and the energy storage unit in the present application. As shown in FIG15 , when an overvoltage occurs in the high-voltage direct-mounted energy storage system, the control system locks the power unit and disconnects the path between the power unit and the energy storage unit, then obtains a second voltage on the bus side of the high-voltage direct-mounted energy storage system and determines that the high-voltage direct-mounted energy storage system has not experienced an overvoltage based on the second voltage and a preset threshold. Specifically, the control system obtains multiple second voltages collected within a preset time period. If none of the multiple second voltages is greater than a first preset threshold, the control system determines that an overvoltage has occurred in the high-voltage direct-mounted energy storage system. Otherwise, the control system determines that an overvoltage still exists in the high-voltage direct-mounted energy storage system. Alternatively, the control system obtains multiple second voltages collected within a preset time period and multiple time derivatives of the multiple second voltages derived with respect to time. If none of the multiple second voltages is greater than the first preset threshold and none of the multiple time derivatives is greater than a second preset threshold, the control system determines that an overvoltage has not occurred in the high-voltage direct-mounted energy storage system. Otherwise, the control system determines that an overvoltage still exists in the high-voltage direct-mounted energy storage system.

[0165] Furthermore, after the control system determines that an overvoltage has occurred in the high-voltage direct-mounted energy storage system, it obtains the first current voltage of the battery pack in the energy storage unit and the second current voltage of the power unit. If the difference between the first current voltage and the second current voltage is not greater than a third preset threshold, the path between the power unit and the energy storage unit is directly opened, and the power unit is unlocked.

[0166] If the difference between the first current voltage and the second current voltage is greater than a third preset threshold, the energy storage unit is connected in series with the voltage divider resistor, and then the path between the energy storage unit and the power unit is opened, thereby unlocking the power unit. In this case, the control unit continues to obtain the third current voltage of the battery pack in the energy storage unit and the fourth current voltage of the power unit. If the difference between the third current voltage and the fourth current voltage is not greater than the third preset threshold, the path between the voltage divider resistor and the energy storage unit is disconnected.

[0167] In summary, the overvoltage protection method of the present application only requires adding a solid-state switch to the current high-voltage direct-mounted energy storage system to achieve overvoltage protection for the high-voltage direct-mounted energy storage system, thereby avoiding functional loss and transient instability caused by frequent disconnection of the high-voltage direct-mounted energy storage system when overvoltage occurs. Therefore, the overvoltage protection method of the present application is low-cost, simple to implement, and safe and reliable in operation.

[0168] 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.

[0169] Based on the same inventive concept, embodiments of the present application also provide an overvoltage protection device for implementing the overvoltage protection method described above. The solution provided by this device is similar to the solution described in the method described above. Therefore, the specific limitations of one or more of the overvoltage protection device embodiments provided below can be found in the above-described limitations of the overvoltage protection method and will not be further elaborated here.

[0170] FIG16 is a block diagram of the structure of an overvoltage protection device in an embodiment of the present application. As shown in FIG16 , an overvoltage protection device 1600 is provided in an embodiment of the present application, including: a first acquisition module 1601, a determination module 1602, and a first disconnection module 1603, wherein:

[0171] A first acquisition module 1601 is configured to acquire a first voltage on the bus side of the high-voltage direct-mounted energy storage system;

[0172] A determination module 1602 is configured to determine whether an overvoltage occurs in the high-voltage direct-mounted energy storage system based on the first voltage and a preset threshold;

[0173] The first disconnection module 1603 is used to disconnect the path between the power unit and the energy storage unit when an overvoltage occurs in the high-voltage direct-mounted energy storage system.

[0174] The overvoltage protection device provided in this embodiment is applied to a high-voltage direct-mounted energy storage system, which includes a power unit and an energy storage unit. The device first obtains a first voltage on the bus side of the high-voltage direct-mounted energy storage system, and then determines whether the high-voltage direct-mounted energy storage system has an overvoltage based on the first voltage and a preset threshold value. In this way, when the high-voltage direct-mounted energy storage system has an overvoltage, the path between the power unit and the energy storage unit is disconnected. Because this embodiment can judge the overvoltage state of the high-voltage direct-mounted energy storage system based on the first voltage on the bus side of the high-voltage direct-mounted energy storage system and the preset threshold value, and then determine whether the high-voltage direct-mounted energy storage system has an overvoltage, and further, when it is determined that the high-voltage direct-mounted energy storage system has an overvoltage, the embodiment can disconnect the path between the power unit and the energy storage unit. Therefore, when the high-voltage direct-mounted energy storage system has an overvoltage, the embodiment can temporarily disconnect the energy storage unit from the high-voltage direct-mounted energy storage system in a timely manner, that is, temporarily disconnect the battery pack in the energy storage unit from the high-voltage direct-mounted energy storage system in a timely manner. Therefore, the device provided in this embodiment solves the problem that when a high-voltage direct-mounted energy storage system generates an overvoltage, the battery pack in the energy storage unit has a very low transient overvoltage stress, and the battery pack fails under the action of overvoltage, causing the high-voltage direct-mounted energy storage system to be abnormal. It provides a device for overvoltage protection of the high-voltage direct-mounted energy storage system, thereby improving the operational stability and safety of the high-voltage direct-mounted energy storage system. In addition, since the present application does not require major changes to the circuit, only the path between the power unit and the energy storage unit is disconnected, and the battery pack in the energy storage unit can be temporarily removed from the high-voltage direct-mounted energy storage system in a timely manner. Therefore, the overvoltage protection device provided in this application is a convenient, fast-acting, and small-change device.

[0175] Optionally, the determining module 1602 includes:

[0176] The determining unit is configured to determine whether an overvoltage occurs in the high-voltage direct-mounted energy storage system based on the multiple bus voltages and a preset threshold value if the first voltage includes multiple bus voltages collected within a preset time period.

[0177] Optionally, the determining unit includes:

[0178] The first determination subunit is used to determine that an overvoltage occurs in the high-voltage direct-mounted energy storage system when multiple bus voltages are all greater than a first preset threshold.

[0179] The second determining subunit is used to determine that no overvoltage occurs in the high-voltage direct-mounted energy storage system when the voltages of the multiple bus bars are not greater than the first preset threshold.

[0180] Optionally, the determining unit includes:

[0181] The acquisition subunit is used to obtain multiple time derivatives of multiple bus voltages after derivation with respect to time.

[0182] The third determination subunit is used to determine that an overvoltage occurs in the high-voltage direct-mounted energy storage system when multiple bus voltages are all greater than a first preset threshold and multiple time derivatives are all greater than a second preset threshold.

[0183] The fourth determination subunit is used to determine that the high-voltage direct-mounted energy storage system has no overvoltage when the multiple bus voltages are not greater than the first preset threshold and the multiple time derivatives are not greater than the second preset threshold.

[0184] Optionally, the overvoltage protection device 1600 further includes:

[0185] The locking module is used to lock the power unit before disconnecting the path between the power unit and the energy storage unit when an overvoltage occurs in the high-voltage direct-mounted energy storage system.

[0186] Optionally, the overvoltage protection device 1600 further includes:

[0187] The second acquisition module is used to obtain a second voltage on the bus side of the high-voltage direct-mounted energy storage system after disconnecting the path between the power unit and the energy storage unit.

[0188] The conduction module is used to conduct the path between the power unit and the energy storage unit if it is determined that the high-voltage direct-mounted energy storage system does not have an overvoltage based on the second voltage and the preset threshold.

[0189] Optionally, the conduction module includes:

[0190] The acquisition unit is used to acquire a first current voltage of the battery pack in the energy storage unit and a second current voltage of the power unit.

[0191] The conducting unit is used to conduct a path between the power unit and the energy storage unit according to the first current voltage and the second current voltage.

[0192] Optionally, the conduction unit includes:

[0193] The first conducting subunit is configured to conduct a path between the power unit and the energy storage unit if the difference between the first current voltage and the second current voltage is not greater than a third preset threshold.

[0194] The second conducting subunit is used to connect the energy storage unit and the voltage dividing resistor in series and then conduct the path between the energy storage unit and the power unit if the difference between the first current voltage and the second current voltage is greater than a third preset threshold.

[0195] Optionally, the overvoltage protection device 1600 further includes:

[0196] The third module is used to obtain the third current voltage of the battery pack in the energy storage unit and the fourth current voltage of the power unit after the path between the energy storage unit and the power unit is connected.

[0197] The second disconnection module is configured to disconnect the path between the voltage-dividing resistor and the energy storage unit if the difference between the third current voltage and the fourth current voltage is not greater than a third preset threshold.

[0198] Optionally, the overvoltage protection device 1600 further includes:

[0199] The unlocking module is used to unlock the power unit after the path between the power unit and the energy storage unit is connected.

[0200] Each module in the above-mentioned overvoltage protection device 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 the form of hardware, or can be stored in a memory in the computer device in the form of software, so that the processor can call and execute the corresponding operations of each module.

[0201] Figure 17 is an internal structure diagram of a computer device in an embodiment of the present application. In an embodiment of the present application, a computer device is provided, which may be a server, and its internal structure diagram may be as shown in Figure 17. The computer device includes a processor, a memory, and a network interface connected via a system bus. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program, and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store relevant data. The network interface of the computer device is used to communicate with an external terminal via a network connection. When the computer program is executed by the processor, an overvoltage protection method is implemented.

[0202] Those skilled in the art will understand that the structure shown in Figure 17 is merely a block diagram of a portion of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than shown in the figure, or combine certain components, or have a different component arrangement.

[0203] In one embodiment, a computer device is provided, including a memory and a processor. The memory stores a computer program, and the processor implements the steps in the above method embodiments when executing the computer program.

[0204] 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 steps in the above-mentioned method embodiments are implemented.

[0205] In one embodiment, a computer program product is provided, including a computer program, which implements the steps in the above method embodiments when executed by a processor.

[0206] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties.

[0207] Those skilled in the art will appreciate that all or part of the processes in the above-mentioned embodiment methods can be implemented by instructing the relevant hardware through a computer program, and 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. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application may include at least one of non-volatile and volatile memory. Non-volatile memory may include read-only memory (ROM), magnetic tape, floppy disk, flash memory or optical memory, etc. Volatile memory may include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0208] The technical features of the above embodiments can be combined arbitrarily. 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 specification.

[0209] The above 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 invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. An overvoltage protection method, characterized in that: Applied to a high-voltage direct-mounted energy storage system, the high-voltage direct-mounted energy storage system includes a power unit and an energy storage unit; the method includes: Obtaining a first voltage on a busbar side of the high-voltage direct-mounted energy storage system; Determining whether an overvoltage occurs in the high-voltage direct-mounted energy storage system based on the first voltage and a preset threshold; When an overvoltage occurs in the high-voltage direct-mounted energy storage system, the path between the power unit and the energy storage unit is disconnected.

2. The method according to claim 1, characterized in that The determining whether the high-voltage direct-mounted energy storage system has an overvoltage according to the first voltage and a preset threshold value includes: If the first voltage includes multiple bus voltages collected within a preset time period, it is determined whether the high-voltage direct-mounted energy storage system has an overvoltage based on the multiple bus voltages and the preset threshold.

3. The method according to claim 2, characterized in that The determining whether the high-voltage direct-mounted energy storage system has an overvoltage according to the multiple bus voltages and the preset threshold value includes: When the plurality of bus voltages are all greater than a first preset threshold, determining that an overvoltage occurs in the high-voltage direct-mounted energy storage system; When the multiple bus voltages are not greater than the first preset threshold, it is determined that the high-voltage direct-mounted energy storage system does not have an overvoltage.

4. The method according to claim 3, characterized in that The determining whether the high-voltage direct-mounted energy storage system has an overvoltage according to the multiple bus voltages and the preset threshold value includes: Obtaining a plurality of time derivatives of the plurality of bus voltages after derivation with respect to time; When the multiple bus voltages are all greater than the first preset threshold, and the multiple time derivatives are all greater than the second preset threshold, it is determined that the high-voltage direct-mounted energy storage system has an overvoltage; When the multiple bus voltages are not greater than the first preset threshold and the multiple time derivatives are not greater than the second preset threshold, it is determined that the high-voltage direct-mounted energy storage system does not have an overvoltage.

5. The method according to any one of claims 1 to 4, characterized in that The method further comprises: In the event of an overvoltage in the high-voltage direct-mounted energy storage system, the power unit is locked before the path between the power unit and the energy storage unit is disconnected.

6. The method according to any one of claims 1 to 5, characterized in that The method further comprises: After disconnecting the path between the power unit and the energy storage unit, obtaining a second voltage on the bus side of the high-voltage direct-mounted energy storage system; If it is determined based on the second voltage and the preset threshold that the high-voltage direct-mounted energy storage system does not have an overvoltage, the path between the power unit and the energy storage unit is opened.

7. The method according to claim 6, characterized in that The conducting path between the power unit and the energy storage unit includes: Obtaining a first current voltage of a battery pack in the energy storage unit and a second current voltage of the power unit; A path between the power unit and the energy storage unit is conducted according to the first current voltage and the second current voltage.

8. The method according to claim 7, characterized in that The step of conducting a path between the power unit and the energy storage unit according to the first current voltage and the second current voltage includes: If the difference between the first current voltage and the second current voltage is not greater than a third preset threshold, the path between the power unit and the energy storage unit is opened.

9. The method according to claim 8, characterized in that The step of conducting a path between the power unit and the energy storage unit according to the first current voltage and the second current voltage includes: If the difference between the first current voltage and the second current voltage is greater than the third preset threshold, the energy storage unit is connected in series with a voltage divider resistor to open a path between the energy storage unit and the power unit.

10. The method according to claim 9, characterized in that The method further comprises: After the path between the energy storage unit and the power unit is connected, obtaining a third current voltage of the battery pack in the energy storage unit and a fourth current voltage of the power unit; If the difference between the third current voltage and the fourth current voltage is not greater than the third preset threshold, the path between the voltage dividing resistor and the energy storage unit is disconnected.

11. The method according to claim 6, characterized in that The method further comprises: After the path between the power unit and the energy storage unit is opened, the power unit is unlocked.

12. An overvoltage protection device, characterized in that: Applicable to a high-voltage direct-mounted energy storage system, the high-voltage direct-mounted energy storage system includes a power unit and an energy storage unit; the device includes: A first acquisition module, configured to acquire a first voltage on the bus side of the high-voltage direct-mounted energy storage system; a determination module, configured to determine whether an overvoltage occurs in the high-voltage direct-mounted energy storage system based on the first voltage and a preset threshold; The first disconnection module is used to disconnect the path between the power unit and the energy storage unit when an overvoltage occurs in the high-voltage direct-mounted energy storage system.

13. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 11 are implemented.

14. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 11 are implemented.

15. A computer program product comprising a computer program, characterized in that When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 11 are implemented.

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