Energy storage valve submodule and high-voltage directly-connected energy storage system

Abstract

An energy storage valve submodule and a high-voltage directly-connected energy storage system. The energy storage valve submodule comprises a power conversion circuit (10), a first capacitor (20), a first energy storage unit (31), and a second energy storage unit (32); the first capacitor (20), the first energy storage unit (31) and the second energy storage unit (32) are all connected in parallel to the power conversion circuit (10); a first connecting line (311) is provided between the first energy storage unit (31) and the power conversion circuit (10); a second connecting line (321) is provided between the second energy storage unit (32) and the power conversion circuit (10); the difference between the equivalent inductance of the first connecting line (311) and the equivalent inductance of the second connecting line (321) is less than a preset threshold.

Description

Energy storage valve sub-module, high-voltage direct-connected energy storage system

[0001] Cross-references to related applications

[0002] This disclosure is based on Chinese Patent Application No. 202411906254.X, filed on December 20, 2024, entitled "Energy Storage Valve Submodule, High-Voltage Direct-Connected Energy Storage System", and claims priority to that Chinese Patent Application, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of energy storage technology, and in particular to an energy storage valve submodule and a high-voltage direct-connected energy storage system. Background Technology

[0004] With the development of large-scale energy storage, high-voltage direct-connected energy storage systems have gradually gained attention. The basic unit of a high-voltage direct-connected energy storage system is multiple cascaded energy storage valve submodules, each of which includes a power conversion circuit and multiple energy storage units. However, in high-voltage DC direct-connected energy storage valve submodules, current exceeding limits can occur within the energy storage units during operation, potentially causing damage. Summary of the Invention

[0005] The main technical problem solved by this application is to provide an energy storage valve submodule and a high-voltage direct-connected energy storage system, in which the equivalent inductance of the first connecting line and the equivalent inductance of the second connecting line are approximately the same, so that the equivalent inductance between energy storage units is approximately the same, thereby improving the stability and reliability of the energy storage valve submodule.

[0006] In a first aspect, embodiments of this application provide an energy storage valve submodule, which includes a power conversion circuit, a first capacitor, a first energy storage unit, and a second energy storage unit. The first capacitor, the first energy storage unit, and the second energy storage unit are all connected in parallel with the power conversion circuit. A first connection line is provided between the first energy storage unit and the power conversion circuit, and a second connection line is provided between the second energy storage unit and the power conversion circuit. The difference between the equivalent inductance of the first connection line and the equivalent inductance of the second connection line is less than a preset threshold.

[0007] In the technical solution of this application embodiment, at the switching moment when the energy storage valve submodule is put into and taken out, the power conversion circuit is equivalent to a step excitation current source, which may cause the first energy storage unit and / or the second energy storage unit to generate over-limit current. By setting the difference between the equivalent inductance of the first connection line and the equivalent inductance of the second connection line to be less than a preset threshold, that is, the equivalent inductance of the first energy storage unit and the equivalent inductance of the second energy storage unit are close to the same, so that the current of the first energy storage unit and the current of the second energy storage unit are close to the same at the switching moment when the energy storage valve submodule is put into and taken out, thereby suppressing the generation of over-limit current in the first energy storage unit and the second energy storage unit at the switching moment when the energy storage valve submodule is put into and taken out, thereby reducing the damage to the first energy storage unit and the second energy storage unit and improving the stability and reliability of the energy storage valve submodule.

[0008] In some embodiments, the first length of the first connecting line is equal to the second length of the second connecting line.

[0009] In the technical solution of this application embodiment, the equivalent inductance of the first connecting line is related to the first length of the first connecting line, and the equivalent inductance of the second connecting line is related to the second length of the second connecting line. By setting the first length of the first connecting line and the second length of the second connecting line to be equal, the equivalent inductance of the first connecting line and the equivalent inductance of the second connecting line can be made equal, thereby making the equivalent inductance of the first energy storage unit and the equivalent inductance of the second energy storage unit equal, so that the current of the first energy storage unit and the current of the second energy storage unit are the same at the switching time of the energy storage valve submodule being put into and taken out, so as to suppress the generation of over-limit current in the first energy storage unit and the second energy storage unit at the switching time of the energy storage valve submodule being put into and taken out.

[0010] In some embodiments, the cross-sectional area of ​​the first connecting line is equal to the cross-sectional area of ​​the second connecting line.

[0011] In the technical solution of this application embodiment, based on the fact that the first length of the first connecting line is equal to the second length of the second connecting line, the cross-sectional area of ​​the first connecting line is set to be equal to the cross-sectional area of ​​the second connecting line. This can further improve the consistency between the equivalent inductance of the first connecting line and the equivalent inductance of the second connecting line, and reduce the risk of the first energy storage unit and the second energy storage unit generating over-limit current at the switching moment of the energy storage valve submodule being put into and taken out.

[0012] In some embodiments, the first length of the first connecting line is less than the second length of the second connecting line, and the cross-sectional area of ​​the second connecting line is greater than the cross-sectional area of ​​the first connecting line.

[0013] In the technical solution of this application embodiment, the equivalent inductance of the first connecting line is related to the cross-sectional area of ​​the first connecting line, and the equivalent inductance of the second connecting line is related to the cross-sectional area of ​​the second connecting line. When the first length of the first connecting line is less than the second length of the second connecting line, by setting the cross-sectional area of ​​the second connecting line to be greater than the cross-sectional area of ​​the first connecting line, the difference between the equivalent inductance of the first connecting line and the equivalent inductance of the second connecting line is less than a preset threshold. This suppresses the generation of over-limit current in the first energy storage unit and the second energy storage unit at the switching moment of the energy storage valve submodule being put into and taken out, thereby reducing damage to the first energy storage unit and the second energy storage unit and improving the stability and reliability of the energy storage valve submodule.

[0014] In some embodiments, the first connecting line includes a first sub-connecting line and a second sub-connecting line arranged in parallel with the first sub-connecting line, the second connecting line includes a third sub-connecting line and a fourth sub-connecting line arranged in parallel with the third sub-connecting line; a first spacing between the first sub-connecting line and the second sub-connecting line is configured to adjust the equivalent inductance of the first connecting line, and a second spacing between the third sub-connecting line and the fourth sub-connecting line is configured to adjust the equivalent inductance of the second connecting line.

[0015] In the technical solution of this application embodiment, the first spacing between the first sub-connecting line and the second sub-connecting line is configured to adjust the equivalent inductance of the first connecting line, and the second spacing between the third sub-connecting line and the fourth sub-connecting line is configured to adjust the equivalent inductance of the second connecting line. By adjusting the first spacing and the second spacing, the difference between the equivalent inductance of the first connecting line and the equivalent inductance of the second connecting line can be less than a preset threshold.

[0016] In some embodiments, when the first length of the first connecting line is less than the second length of the second connecting line, the first spacing is greater than the second spacing.

[0017] In the technical solution of this application embodiment, when the first length of the first connecting line is less than the second length of the second connecting line, the equivalent inductance of the second connecting line is greater than the equivalent inductance of the first connecting line. The mutual inductance between the first sub-connecting line and the second sub-connecting line is related to the first spacing, and the mutual inductance between the third sub-connecting line and the fourth sub-connecting line is related to the second spacing. By making the first spacing greater than the second spacing, the mutual inductance between the first sub-connecting line and the second sub-connecting line is made less than the mutual inductance between the third sub-connecting line and the fourth sub-connecting line. This adjusts the equivalent inductance of the second connecting line and the equivalent inductance of the first connecting line, enabling the difference between the equivalent inductance of the first connecting line and the equivalent inductance of the second connecting line to be less than a preset threshold.

[0018] In some embodiments, the cross-sectional area of ​​the first sub-connecting line is smaller than the cross-sectional area of ​​the third sub-connecting line; and / or, the cross-sectional area of ​​the second sub-connecting line is smaller than the cross-sectional area of ​​the fourth sub-connecting line.

[0019] In the technical solution of this application embodiment, the first spacing is greater than the second spacing. When the mutual inductance between the first sub-connecting line and the second sub-connecting line is less than the mutual inductance between the third sub-connecting line and the fourth sub-connecting line, the equivalent inductance of the first connecting line is related to the cross-sectional area of ​​the first sub-connecting line and / or the cross-sectional area of ​​the second sub-connecting line, and the equivalent inductance of the second connecting line is related to the cross-sectional area of ​​the third sub-connecting line and / or the cross-sectional area of ​​the fourth sub-connecting line. By adjusting the equivalent inductance of the second connecting line and the equivalent inductance of the first connecting line, the difference between the equivalent inductance of the first connecting line and the equivalent inductance of the second connecting line can be made less than a preset threshold.

[0020] In some embodiments, the direction of the current flowing through the first sub-connector is opposite to the direction of the current flowing through the second sub-connector; the direction of the current flowing through the third sub-connector is opposite to the direction of the current flowing through the fourth sub-connector.

[0021] In the technical solution of this application embodiment, the first sub-connecting line, the second sub-connecting line, the third sub-connecting line, and the fourth sub-connecting line are arranged in parallel with opposite current directions. This can increase the mutual inductance between the first sub-connecting line and the second sub-connecting line, as well as the mutual inductance between the third sub-connecting line and the fourth sub-connecting line, thereby reducing the equivalent inductance of the first connecting line and the equivalent inductance of the second connecting line, and thus reducing the difference between the equivalent inductance of the first connecting line and the equivalent inductance of the second connecting line.

[0022] In some embodiments, both the first connecting line and the second connecting line are cables.

[0023] In the technical solution of this application embodiment, by setting both the first connecting line and the second connecting line to be cables, and the spacing between the positive and negative lines in the cables is small, the mutual inductance between the positive and negative lines in the cables is increased, thereby reducing the equivalent inductance of the first connecting line and the equivalent inductance of the second connecting line, so that the difference between the equivalent inductance of the first connecting line and the equivalent inductance of the second connecting line is less than a preset threshold.

[0024] In some embodiments, the power conversion circuit is located spatially between the first energy storage unit and the second energy storage unit.

[0025] In the technical solution of this application embodiment, by positioning the power conversion circuit between the first energy storage unit and the second energy storage unit in the spatial location, the difference between the distance between the first energy storage unit and the power conversion circuit and the distance between the second energy storage unit and the power conversion circuit is reduced, that is, the difference between the length of the first connecting line and the length of the second connecting line is reduced, and the difference between the equivalent inductance of the first connecting line and the equivalent inductance of the second connecting line is less than a preset threshold.

[0026] In some embodiments, the energy storage valve submodule further includes a resistive element connected in series with the first capacitor.

[0027] In the technical solution of this application embodiment, by connecting a resistor element in series on the branch where the first capacitor is located, the resistor element provides the resistance value required to suppress the underdamped oscillating current generated by the energy storage valve submodule at the time of commissioning. This is not only economical and convenient, but also greatly reduces the additional impact on the overall function of the energy storage valve submodule and further increases the stability of the energy storage valve submodule.

[0028] In some embodiments, the first capacitor and the resistive element constitute a RC branch, and the energy storage valve submodule further includes a second capacitor, which is connected in parallel with the RC branch.

[0029] In the technical solution of this application embodiment, since the second capacitor is connected in parallel with the RC branch, the second capacitor can be used to buffer the high-frequency current in the current of the energy storage valve submodule at the time of activation, so as to reduce the rate of change of the turn-off current at the time of turn-off of the switching switch, thereby reducing the overvoltage stress at the time of turn-off of the switching switch tube.

[0030] In some embodiments, the input current of the energy storage valve submodule includes a stepped wave.

[0031] In the technical solution of this application embodiment, for scenarios where the input current of the energy storage valve submodule includes a stepped wave, since the stepped wave may cause the first energy storage unit and / or the second energy storage unit to generate over-limit current; by setting the difference between the equivalent inductance of the first connection line and the equivalent inductance of the second connection line to be less than a preset threshold, that is, the equivalent inductance of the first energy storage unit and the equivalent inductance of the second energy storage unit are close to the same, the current of the first energy storage unit and the current of the second energy storage unit at the step moment of the stepped wave can be made close to the same, thereby suppressing the generation of over-limit current in the first energy storage unit and the second energy storage unit at the step moment, thereby reducing the damage to the first energy storage unit and the second energy storage unit and improving the stability and reliability of the energy storage valve submodule.

[0032] In some embodiments, the energy storage valve submodule further includes a connecting busbar, and both the first connecting line and the second connecting line are connected to the power conversion circuit through the connecting busbar.

[0033] In the technical solution of this application embodiment, since the equivalent inductance of the connecting busbar is usually low, both the first connecting line and the second connecting line are connected to the power conversion circuit through the connecting busbar. This can reduce the equivalent inductance of the current transmission path between the first energy storage unit and the power conversion circuit, and also reduce the equivalent inductance of the current transmission path between the second energy storage unit and the power conversion circuit. As a result, the equivalent inductance of the current transmission path between the first energy storage unit and the power conversion circuit, and the equivalent inductance of the current transmission path between the second energy storage unit and the power conversion circuit, can be made to be approximately the same. This helps to suppress the generation of over-limit current in the first energy storage unit and the second energy storage unit at the switching moment when the energy storage valve submodule is put into and taken out.

[0034] In some embodiments, the current transmission path between the power conversion circuit and the first energy storage unit on the connecting busbar has a third length, and the current transmission path between the power conversion circuit and the second energy storage unit on the connecting busbar has a fourth length, and the difference between the third length and the fourth length is less than a preset length threshold.

[0035] In the technical solution of this application embodiment, the difference between the third length and the fourth length is less than a preset length threshold, that is, the transmission path length of the current between the power conversion circuit and the first energy storage unit on the connecting busbar and the transmission path length of the current between the power conversion circuit and the second energy storage unit on the connecting busbar are approximately equal, thereby making the equivalent inductance of the current transmission path between the first energy storage unit and the power conversion circuit and the equivalent inductance of the current transmission path between the second energy storage unit and the power conversion circuit approximately the same.

[0036] In some embodiments, the connecting busbar includes a first connecting busbar and a second connecting busbar. The first connecting busbar is connected to the positive terminals of the first energy storage unit and the second energy storage unit, and is connected to the positive terminal of the power conversion circuit through a first busbar. The second connecting busbar is connected to the negative terminals of the first energy storage unit and the second energy storage unit, and is connected to the negative terminal of the power conversion circuit through a second busbar. The first busbar and the second busbar are located spatially between the first energy storage unit and the second energy storage unit.

[0037] In the technical solution of this application embodiment, the first connecting bar connecting the positive terminal of the first energy storage unit and the positive terminal of the second energy storage unit is connected to the positive terminal of the power conversion circuit through the first bus point. The second connecting bar connecting the negative terminal of the first energy storage unit and the negative terminal of the second energy storage unit is connected to the negative terminal of the power conversion circuit through the second bus point. Since the first bus point and the second bus point are located between the first energy storage unit and the second energy storage unit in spatial position, the difference in distance between the positive terminal of the first energy storage unit and the positive terminal of the second energy storage unit to the first bus point can be reduced, and the difference in distance between the negative terminal of the first energy storage unit and the negative terminal of the second energy storage unit to the second bus point can also be reduced. That is, the difference between the equivalent inductance of the current transmission path between the first energy storage unit and the power conversion circuit and the equivalent inductance of the current transmission path between the second energy storage unit and the power conversion circuit can be reduced.

[0038] In some embodiments, the energy storage valve submodule further includes an inductor, through which both the first connecting line and the second connecting line are connected to the power conversion circuit.

[0039] In the technical solution of this application embodiment, by setting both the first connecting line and the second connecting line to be connected to the power conversion circuit through the inductor element, the same inductance can be introduced into the current transmission path between the first energy storage unit and the power conversion circuit, as well as the current transmission path between the second energy storage unit and the power conversion circuit. This reduces the impact of the difference between the equivalent inductance of the first energy storage unit and the equivalent inductance of the second energy storage unit during the underdamped oscillation process. As a result, at the switching moment when the energy storage valve submodule is put into and taken out, the current between the first energy storage unit and the power conversion circuit and the current between the second energy storage unit and the power conversion circuit tend to be consistent, thereby reducing the risk of the first energy storage unit and the second energy storage unit generating over-limit current.

[0040] In some embodiments, the inductance value of the inductor is greater than a preset multiple of the target inductance value, and the target inductance value is the average value between the equivalent inductance of the first connecting line and the equivalent inductance of the second connecting line.

[0041] In the technical solution of this application embodiment, the inductance value of the inductor is greater than a preset multiple of the average value between the equivalent inductance of the first connecting line and the equivalent inductance of the second connecting line. This can further reduce the influence of the difference between the equivalent inductance of the first energy storage unit and the equivalent inductance of the second energy storage unit during the underdamped oscillation process, thereby further reducing the risk of the first energy storage unit and the second energy storage unit generating over-limit current.

[0042] In some embodiments, the energy storage valve submodule further includes an isolating switch unit connected between the first energy storage unit and the first capacitor, and / or the isolating switch unit is connected between the second energy storage unit and the first capacitor.

[0043] In the technical solution of this application embodiment, the disconnecting switch unit is connected between the first energy storage unit and the first capacitor, and / or the disconnecting switch unit is connected between the second energy storage unit and the first capacitor. The disconnecting switch unit can control the on / off state of the first energy storage unit and / or the second energy storage unit to achieve protection of the first energy storage unit and / or the second energy storage unit, so that the energy storage valve submodule can work stably.

[0044] Secondly, embodiments of this application provide a high-voltage direct-connected energy storage system, which includes a main circuit and the aforementioned energy storage valve sub-modules, with two connection ports of each energy storage valve sub-module connected to the main circuit.

[0045] It is understood that the beneficial effects of the second aspect mentioned above can be found in the relevant descriptions in the first aspect mentioned above.

[0046] The above description is merely an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more apparent and understandable, the following are exemplary embodiments of this application. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0048] Figure 1 is a schematic diagram of the architecture of an embodiment of the high-voltage AC direct-connected energy storage system provided in this application;

[0049] Figure 2 is a circuit diagram of an embodiment of the energy storage valve submodule provided in this application;

[0050] Figure 3 is a schematic diagram of an embodiment of the equivalent inductance and equivalent internal resistance of the energy storage unit in the energy storage valve submodule in Figure 2.

[0051] Figure 4 is a circuit diagram of another embodiment of the energy storage valve submodule provided in this application;

[0052] Figure 5 is a circuit diagram of an embodiment of the power conversion circuit in Figure 4;

[0053] Figure 6 is a circuit diagram of an embodiment of the energy storage valve submodule provided in this application;

[0054] Figure 7 is a structural schematic diagram of an embodiment of the energy storage valve submodule provided in this application;

[0055] Figure 8 is a circuit diagram of an embodiment of the energy storage valve submodule provided in this application.

[0056] Figure 9 is a circuit diagram of an embodiment of the energy storage valve submodule provided in this application;

[0057] Figure 10 is a structural schematic diagram of an embodiment of the energy storage valve submodule provided in this application;

[0058] Figure 11 is a structural schematic diagram of an embodiment of the energy storage valve submodule provided in this application;

[0059] Figure 12 is a circuit diagram of an embodiment of the energy storage valve submodule provided in this application;

[0060] Figure 13 is a circuit diagram of an embodiment of the energy storage valve submodule provided in this application.

[0061] The reference numerals in the accompanying drawings of the specific implementation are as follows: Power conversion circuit 10, first capacitor 20, resistor element 21, first energy storage unit 31, second energy storage unit 32, first connecting line 311, second connecting line 321, first sub-connecting line 3111, second sub-connecting line 3112, third sub-connecting line 3211, fourth sub-connecting line 3212, second capacitor 40, bypass circuit 50, port S1, port S2, switch Q1, switch Q2, power device T1, power device T2, diode D1, diode D2, isolating switch K1, isolating switch K2, starting resistor R, reactor Z1, reactor Z2, starting resistor bypass switch K3, energy storage module SM#m, connecting busbar 60, first connecting busbar 61, second connecting busbar 62, first busbar 611, second busbar 621. Detailed Implementation

[0062] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0063] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0064] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0065] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0066] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0067] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0068] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0069] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0070] High-voltage direct-connected energy storage systems are a new type of energy storage system. Utilizing modular multilevel cascading technology, multiple energy storage valve submodules are cascaded to simultaneously achieve AC / DC power conversion and energy storage. They offer advantages such as high modularity and good harmonic characteristics, leading to their increasingly widespread application in power grids. Each energy storage valve submodule in a high-voltage direct-connected energy storage system includes multiple energy storage units, and each energy storage unit contains a battery cluster. In practical applications, the charging and discharging of the energy storage units within each cascaded energy storage valve submodule can be controlled.

[0071] Taking a high-voltage direct-connected energy storage system as an example, as shown in Figure 1, Figure 1 is a schematic diagram of the architecture of an embodiment of the high-voltage direct-connected energy storage system provided in this application. It utilizes modular cascading technology to cascade multiple energy storage sub-modules. The high-voltage direct-connected energy storage system may include two isolating switches K1 and K2, a starting resistor R, two reactors Z1 and Z2, a starting resistor bypass switch K3, and m energy storage modules SM#m, where m is 1, 2, 3, ..., n. Their connection relationships are shown in Figure 1. In other embodiments, such as a high-voltage AC direct-connected energy storage system, a converter valve can also convert DC power into multiphase AC power. The high-voltage direct-connected energy storage system includes a multiphase energy storage cascade chain, and each phase energy storage cascade chain may include a bridge arm reactor and multiple energy storage modules, etc.

[0072] The topology of the energy storage valve submodule in the high-voltage direct-connected energy storage system of this application embodiment is shown in Figure 2. It includes a power conversion circuit 10, a first capacitor 20, a first energy storage unit 31 and a second energy storage unit 32. In Figure 2, S1 and S2 represent two connection ports. Each energy storage valve submodule needs to be connected to the main circuit of the high-voltage direct-connected energy storage system through ports S1 and S2 in order to be connected to the high-voltage power grid through the main circuit.

[0073] The equivalent resistance, equivalent inductance, and first capacitor within the energy storage unit of the energy storage valve submodule are equivalent to a parallel RLC network. The energy storage valve submodule operates in two modes within the entire high-voltage direct-connected energy storage system: on and off. During the switching between on and off states, current from the main circuit of the high-voltage direct-connected energy storage system enters the energy storage valve submodule. Because the switching devices of the energy storage valve submodule, such as insulated-gate bipolar transistors (IGBTs), have extremely fast turn-on and turn-off speeds, the current in the main circuit of the high-voltage direct-connected energy storage system can be considered a step current source excitation for the RLC network. It is understandable that in a high-voltage direct-connected energy storage system, the input current in the main circuit during the switching between on and off states of the energy storage valve submodule can be considered a stepped wave, whereas in a low-voltage energy storage system, no stepped wave is generated in the input current.

[0074] Please refer to Figure 3. Figure 3 is a schematic diagram of an embodiment of the equivalent inductance and equivalent internal resistance of the energy storage unit in the energy storage valve submodule in Figure 2. In the figure, L1 represents the equivalent inductance of the first energy storage unit 31, R1 represents the equivalent internal resistance of the first energy storage unit 31, Ln represents the equivalent inductance of the second energy storage unit 32, and Rn represents the equivalent internal resistance of the second energy storage unit 32. For example, n equals 2. I / P represents the step current source excitation. The power conversion circuit 10 and the first capacitor 20 in the energy storage valve submodule are not shown in Figure 3. The power conversion circuit 10 is equivalent to the step current source excitation.

[0075] Because the equivalent internal resistance and equivalent stray inductance of different energy storage units may differ—for example, the equivalent inductance L1 of the first energy storage unit 31 is different from that of the second energy storage unit 32, and the equivalent internal resistance R1 of the first energy storage unit 31 is different from that of the second energy storage unit 32—the currents of the first energy storage unit 31 and the second energy storage unit 32 are different. During the switching between the activation and deactivation of the energy storage valve submodule, under the step current source excitation I / P, the difference in current between the first energy storage unit 31 and the second energy storage unit 32 makes it easier to form asymmetrical oscillations. This leads to an increase in the amplitude of the oscillation current, and consequently, the charging and discharging current of the first energy storage unit 31 and / or the second energy storage unit 32 may exceed the rated operating current due to the oscillation current. In other words, the first energy storage unit 31 and / or the second energy storage unit 32 will experience current over-limit. At this time, if the rated DC current is used as the long-term operating current of the first energy storage unit 31 and / or the second energy storage unit 32, the over-limit current will damage the first energy storage unit 31 and / or the second energy storage unit 32. For example, overcurrent in the energy storage unit will cause damage, deterioration, and reduced lifespan of the energy storage unit. If the peak value of the over-limit current is used as the long-term operating current of the first energy storage unit 31 and / or the second energy storage unit 32, the current output capability of the first energy storage unit 31 and / or the second energy storage unit 32 will be reduced, thereby reducing the power of the energy storage valve submodule.

[0076] In some embodiments, when the equivalent internal resistance R1 of the first energy storage unit 31 and the equivalent internal resistance Rn of the second energy storage unit 32 are the same, the equivalent inductance L1 of the first energy storage unit 31 and the equivalent inductance Ln of the second energy storage unit 32 are different, resulting in different currents in the first energy storage unit 31 and the second energy storage unit 32, which may cause damage to the first energy storage unit 31 and / or the second energy storage unit 32.

[0077] This application provides an energy storage valve submodule and a high-voltage direct-connected energy storage system. The energy storage valve submodule includes a power conversion circuit 10, a first capacitor 20, a first energy storage unit 31, and a second energy storage unit 32. The first capacitor 20, the first energy storage unit 31, and the second energy storage unit 32 are all connected in parallel with the power conversion circuit 10. A first connection line 311 connects the first energy storage unit 31 to the power conversion circuit 10, and a second connection line 321 connects the second energy storage unit 32 to the power conversion circuit 10. The difference between the equivalent inductance of the first connection line 311 and the equivalent inductance of the second connection line 321 is less than a preset threshold.

[0078] The preset threshold can be equal to a first preset ratio of the sum of the equivalent inductance of the first connecting line 311 and the equivalent inductance of the second connecting line 321. The first preset ratio ranges from 5% to 15%, i.e., the first preset ratio can be 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, or 15%, etc. For example, if the equivalent inductance of the first connecting line 311 is 9 Henry (H) and the equivalent inductance of the second connecting line 321 is 10H, and the average of the sum of the equivalent inductances of the first connecting line 311 and the second connecting line 321 is 9.5H, and the first preset ratio is 10%, then the preset threshold is 0.95.

[0079] In some embodiments, the preset threshold can be a first preset ratio of the equivalent inductance of the first connecting line 311 or the equivalent inductance of the second connecting line 321. For example, if the preset threshold is 10% of the equivalent inductance of the second connecting line 321, then the preset threshold is 1H.

[0080] In this design, the equivalent inductance L1 of the first energy storage unit 31 is determined by the equivalent inductance of the first connecting line 311, and the equivalent inductance Ln of the second energy storage unit 32 is determined by the equivalent inductance of the second connecting line 321. By ensuring that the difference between the equivalent inductance of the first connecting line 311 and the equivalent inductance of the second connecting line 321 is less than a preset threshold, the equivalent inductances of the first connecting line 311 and the second connecting line 321 are made approximately the same, thereby making the equivalent inductance L1 of the first energy storage unit 31 and the equivalent inductance Ln of the second energy storage unit 32 approximately the same.

[0081] At the switching moment when the energy storage valve submodule is put into operation and cut off, the power conversion circuit 10 is equivalent to a step excitation current source, which may cause the first energy storage unit 31 and / or the second energy storage unit 32 to generate over-limit current. By setting the difference between the equivalent inductance of the first connection line 311 and the equivalent inductance of the second connection line 321 to be less than a preset threshold, that is, the equivalent inductance L1 of the first energy storage unit 31 and the equivalent inductance Ln of the second energy storage unit 32 are close to the same, so that the current of the first energy storage unit 31 and the current of the second energy storage unit 32 are close to the same at the switching moment when the energy storage valve submodule is put into operation and cut off, thereby suppressing the generation of over-limit current in the first energy storage unit 31 and the second energy storage unit 32 at the switching moment when the energy storage valve submodule is put into operation and cut off, thereby reducing the damage to the first energy storage unit 31 and the second energy storage unit 32, and improving the stability and reliability of the energy storage valve submodule.

[0082] According to some embodiments of this application, as shown in Figures 2, 3, and 4, Figure 4 is a circuit diagram of another embodiment of the energy storage valve submodule provided in this application. The energy storage valve submodule includes a power conversion circuit 10, a first capacitor 20, a first energy storage unit 31, and a second energy storage unit 32. The first capacitor 20, the first energy storage unit 31, and the second energy storage unit 32 are all connected in parallel with the power conversion circuit 10. A first connection line 311 connects the first energy storage unit 31 to the power conversion circuit 10, and a second connection line 321 connects the second energy storage unit 32 to the power conversion circuit 10. The difference between the equivalent inductance of the first connection line 311 and the equivalent inductance of the second connection line 321 is less than a preset threshold.

[0083] In this embodiment, the term "energy storage valve submodule" broadly refers to any submodule in a high-voltage direct-connected energy storage system. This energy storage system, in relation to the power flow of the power grid, can regulate the direction or magnitude of the power flow, functioning similarly to a valve, and is therefore also called an energy storage valve. However, it is important to emphasize that the term "energy storage valve submodule" used in this embodiment is merely an example of a name for each submodule within the energy storage system and does not limit the function, structure, or application scenario of each submodule. Therefore, in practice, it can also be referred to as an energy storage submodule, charge / discharge electronic module, submodule, etc., depending on actual needs. This embodiment does not limit the names of the submodules in the energy storage system.

[0084] Specifically, the difference between the equivalent inductance of the first connecting line 311 and the equivalent inductance of the second connecting line 321 is less than a preset threshold, so that the equivalent inductances of the first connecting line 311 and the second connecting line 321 are approximately the same. For example, if the equivalent inductance of the first connecting line 311 is 9H and the equivalent inductance of the second connecting line 321 is 10H, and the preset threshold is 1.5H, then 1H is less than 1.5H, meaning the difference between the equivalent inductances of the first connecting line 311 and the second connecting line 321 is less than the preset threshold. The equivalent inductance of the first connecting line 311 is close to the equivalent inductance of the second connecting line 321, including but not limited to: the equivalent inductance of the first connecting line 311 is equal to the equivalent inductance of the second connecting line 321; or, the equivalent inductance of the first connecting line 311 is less than the equivalent inductance of the second connecting line 321; or, the equivalent inductance of the first connecting line 311 is greater than the equivalent inductance of the second connecting line 321.

[0085] In some embodiments, the equivalent inductance of the first connecting line 311 is nearly the same as the equivalent inductance of the second connecting line 321, and thus the equivalent inductance L1 of the first energy storage unit 31 and the equivalent inductance Ln of the second energy storage unit 32 are nearly the same.

[0086] In some embodiments, the energy storage valve submodule may include multiple energy storage units, wherein the first energy storage unit 31 is one of the multiple energy storage units, and the second energy storage unit 32 is another of the multiple energy storage units. The equivalent inductance of the first connecting line 311 is approximately the same as the equivalent inductance of the second connecting line 321, which means that the equivalent inductance of the connecting lines between any two energy storage units in the energy storage valve submodule and the power conversion circuit 10 is approximately the same. The first energy storage unit 31 and the second energy storage unit 32 may refer to different battery clusters, which are battery combinations consisting of multiple battery cells connected in series, parallel, or series-parallel configurations.

[0087] It should be noted that the energy storage valve submodule provided in this application embodiment can be used to improve the consistency of stray inductance between the connection lines of energy storage units and power conversion circuits in different battery clusters, and can also be used to improve the consistency of stray inductance between different boxes in the same battery cluster, which is not limited here.

[0088] In some embodiments, the first capacitor 20 includes a DC support capacitor, which is a capacitor located at the DC terminal of the energy storage valve submodule, has a large capacitance value, and is used to support the voltage of the energy storage valve submodule or suppress voltage fluctuations of the energy storage valve submodule.

[0089] In some embodiments, the power conversion circuit 10 mainly realizes two operating modes—the activation and deactivation of the first energy storage unit 31 and the second energy storage unit 32—during the charging and discharging states through different pathways. The power conversion circuit 10 can be implemented as a half-bridge circuit composed of power semiconductor devices, a full-bridge circuit composed of power semiconductor devices, or a quasi-full-bridge circuit composed of power semiconductor devices, etc.

[0090] This application embodiment sets the difference between the equivalent inductance of the first connecting line 311 and the equivalent inductance of the second connecting line 321 to be less than a preset threshold, that is, the equivalent inductance L1 of the first energy storage unit 31 and the equivalent inductance Ln of the second energy storage unit 32 are nearly the same. This makes the current of the first energy storage unit 31 and the current of the second energy storage unit 32 nearly the same at the switching time when the energy storage valve submodule is put into operation and cut off. In this way, the over-limit current generated by the first energy storage unit 31 and the second energy storage unit 32 is suppressed at the switching time when the energy storage valve submodule is put into operation and cut off, thereby reducing the damage to the first energy storage unit 31 and the second energy storage unit 32 and improving the stability and reliability of the energy storage valve submodule.

[0091] According to some embodiments of this application, as shown in FIG5, FIG5 is a circuit diagram of an embodiment of the power conversion circuit in FIG4. FIG5 illustrates a half-bridge circuit composed of power semiconductor devices, wherein T1 and T2 are both power devices, for example, they can be implemented as insulated gate bipolar transistors (IGBTs).

[0092] Taking power devices T1 and T2 in power conversion circuit 10 as examples, since IGBTs are switching transistors, the gates of power devices T1 and T2 in Figure 5 are both connected to a driving circuit, mainly used to drive the power devices T1 and T2 to turn on and off. However, for the sake of clarity and highlighting the key points, the driving circuits connecting the gates of power devices T1 and T2 are not shown in this embodiment.

[0093] In actual operation, the first energy storage unit 31 and the second energy storage unit 32 in the energy storage valve submodule are divided into charging mode and disconnection mode, as well as discharging mode and disconnection mode. Taking Figure 5 as an example, the working principle of the above charging mode and disconnection mode is explained with reference to the circuit diagram as follows:

[0094] The first energy storage unit 31 and the second energy storage unit 32 are in the charging state of the operation mode: the power device T2 is turned off, and the diode D2 and the power device T1 are not conducting due to the reverse voltage. Then the current in the main circuit of the high-voltage direct-connected energy storage system enters from port S1, passes through the diode D1, enters the first energy storage unit 31 and the second energy storage unit 32, and then flows out through port S2 to form a circuit, so that the first energy storage unit 31 and the second energy storage unit 32 can be charged.

[0095] In the disconnection mode where the first energy storage unit 31 and the second energy storage unit 32 are in a charging state: power device T2 is turned on. Since the voltage drop across power device T2 is very low when it is turned on, the current in the main circuit of the high-voltage direct-connected energy storage system enters from port S1 and flows directly through power device T2 and then out from port S2, forming a loop. This disconnects the first energy storage unit 31 and the second energy storage unit 32 from the main circuit of the high-voltage direct-connected energy storage system, and the first energy storage unit 31 and the second energy storage unit 32 are no longer charged. At this time, because there is voltage on the first energy storage unit 31 and the second energy storage unit 32, diode D1 is reverse voltage clamped and is in the cutoff state.

[0096] The first energy storage unit 31 and the second energy storage unit 32 are in the discharge state of the operation mode: power device T2, diode D2 and diode D1 are not conducting, while power device T1 is conducting. Then the current on the main circuit of the high-voltage direct-connected energy storage system enters the first energy storage unit 31 and the second energy storage unit 32 directly from port S2, passes through power device T1 and flows out from port S1 to form a circuit, so that the first energy storage unit 31 and the second energy storage unit 32 are in the discharge state.

[0097] The first energy storage unit 31 and the second energy storage unit 32 are in the discharge state cut-off mode: power device T2, diode D1 and power device T1 are not conducting. The current in the main circuit of the high-voltage direct-connected energy storage system enters from port S2, flows through diode D2 and flows directly out to port S1 to form a circuit, completely cutting off the first energy storage unit 31 and the second energy storage unit 32 from the main circuit, and no longer discharging.

[0098] As mentioned above, the equivalent internal resistance of the first energy storage unit 31 and the equivalent internal resistance of the second energy storage unit 32 mainly originate from the internal resistance of the numerous series-parallel connected cells. The equivalent internal resistance is relatively low, causing it to fluctuate significantly with the charging and discharging frequency. Therefore, it is difficult to change the current of the first energy storage unit 31 and the second energy storage unit 32 by changing their equivalent internal resistances. Instead, the current of the first energy storage unit 31 and the second energy storage unit 32 is changed by changing their equivalent inductance L1 and equivalent inductance Ln. The equivalent inductance L1 of the first energy storage unit 31 is related to the equivalent inductance of the first connecting line 311, and the equivalent inductance Ln of the second energy storage unit 32 is related to the equivalent inductance of the second connecting line 321.

[0099] According to some embodiments of this application, the first length of the first connecting line 311 is equal to the second length of the second connecting line 321.

[0100] In some embodiments, the first connecting line 311 and the second connecting line 321 may be the same type of cable. The cross-sectional shape of the first connecting line 311 and the cross-sectional shape of the second connecting line 321 are the same, and the cross-sectional shape of the first connecting line 311 includes, but is not limited to, a circle, a rectangle or other irregular shapes.

[0101] In one embodiment, the cross-sectional shape of the first connecting line 311 and the cross-sectional shape of the second connecting line 321 are circular. The equivalent inductance of the first connecting line 311 and the equivalent inductance of the second connecting line 321 are calculated as shown in the following formula (1):

[0102] Where w is the first length of the first connecting line 311 or the second length of the second connecting line 311, and r is the cross-sectional radius of the first connecting line 311 or the cross-sectional radius of the second connecting line 311.

[0103] When the first length w1 of the first connecting line 311 and the second length w of the second connecting line 321 n When the inductances are equal and the radius is r, the equivalent inductance L11 of the first connecting line 311 is shown in the following formula (2):

[0104] The equivalent inductance Ln1 of the second connecting line 321 is shown in the following formula (3):

[0105] At this point, L11 = Ln1, that is, the first length w1 of the first connecting line 311 and the second length w of the second connecting line 321. n When they are equal, the equivalent inductance of the first connection line 311 is equal to the equivalent inductance of the second connection line 321.

[0106] In some embodiments, when the equivalent internal resistance R1 of the first energy storage unit 31 and the equivalent internal resistance Rn of the second energy storage unit 32 are the same, the first length of the first connecting line 311 is equal to the second length of the second connecting line 321, that is, the equivalent inductance L11 of the first connecting line 311 is equal to the equivalent inductance Ln1 of the second connecting line 321, and the equivalent inductance L1 of the first energy storage unit 31 and the equivalent inductance Ln of the second energy storage unit 32 are equal.

[0107] In this embodiment, the equivalent inductance of the first connecting line 311 is related to its first length, and the equivalent inductance of the second connecting line 321 is related to its second length. By setting the first length of the first connecting line 311 and the second length of the second connecting line 321 to be equal, the equivalent inductance of the first connecting line 311 and the equivalent inductance of the second connecting line 321 can be made equal. Thus, the equivalent inductance L1 of the first energy storage unit 31 and the equivalent inductance Ln of the second energy storage unit 32 are equal, so that the current of the first energy storage unit 31 and the current of the second energy storage unit 32 are the same at the switching time when the energy storage valve submodule is put into and taken out, thereby suppressing the generation of over-limit current in the first energy storage unit 31 and the second energy storage unit 32 at the switching time when the energy storage valve submodule is put into and taken out.

[0108] According to some embodiments of this application, the first length of the first connecting line 311 is less than the second length of the second connecting line 321, and the cross-sectional area of ​​the second connecting line 321 is greater than the cross-sectional area of ​​the first connecting line 311.

[0109] In some embodiments, the first connecting line 311 and the second connecting line 321 can be the same type of cable, and the first length w1 of the first connecting line 311 is less than the second length w of the second connecting line 321. n The cross-sectional area of ​​the second connecting line 321 is larger than that of the first connecting line 311. For example, the cross-sectional shape of the first connecting line 311 and the cross-sectional shape of the second connecting line 321 are circular, and the second diameter r of the second connecting line 321 is... n The first diameter r1 of the second connecting line 321 is greater than that of the first connecting line 311, so that the cross-sectional area of ​​the second connecting line 321 is greater than that of the first connecting line 311.

[0110] Taking the cross-sectional shape of the first connecting line 311 and the cross-sectional shape of the second connecting line 321 as circular as an example, the equivalent inductance L11 of the first connecting line 311 is shown in the following formula (4):

[0111] The equivalent inductance Ln1 of the second connecting line 321 is shown in the following formula (5):

[0112] The first length w1 of the first connecting line 311 is less than the second length w of the second connecting line 321. n At that time, by adding the second diameter r of the second connecting line 321 n So that the second diameter r of the second connecting line 321 n The first diameter r1 of the first connecting line 311 is greater than the second diameter r1 of the second connecting line 321, and the difference between the equivalent inductance L11 of the first connecting line 311 and the equivalent inductance Ln1 of the second connecting line 321 is less than a preset threshold. That is, when the first length of the first connecting line 311 is less than the second length of the second connecting line 321, and the cross-sectional area of ​​the second connecting line 321 is greater than the cross-sectional area of ​​the first connecting line 311, the equivalent inductance L11 of the first connecting line 311 and the equivalent inductance Ln1 of the second connecting line 321 can approach the same value.

[0113] For example, the second length w of the second connecting line 321 n If the first length w1 of the first connecting line 311 is twice the first length w1, then the second diameter r of the second connecting line 321 is... n The diameter r1 of the first connecting line 311 is twice that of the first connecting line 311, so that the equivalent inductance L11 of the first connecting line 311 is approximately the same as the equivalent inductance Ln1 of the second connecting line 321. In this embodiment, the equivalent inductance L11 of the first connecting line 311 is related to its cross-sectional area, and the equivalent inductance Ln1 of the second connecting line 321 is related to its cross-sectional area. When the first length of the first connecting line 311 is less than the second length of the second connecting line 321, by setting the cross-sectional area of ​​the second connecting line 321 to be greater than that of the first connecting line 311, the difference between the equivalent inductance of the first connecting line 311 and the equivalent inductance of the second connecting line 321 is less than a preset threshold. This suppresses the generation of over-limit current in the first energy storage unit 31 and the second energy storage unit 32 at the switching moments of the energy storage valve submodule's activation and deactivation, thereby reducing damage to the first energy storage unit 31 and the second energy storage unit 32 and improving the stability and reliability of the energy storage valve submodule.

[0114] In some embodiments, the first length w1 of the first connecting line 311 is greater than the second length w of the second connecting line 321. n The cross-sectional area of ​​the second connecting line 321 is smaller than that of the first connecting line 311. For example, the cross-sectional shape of the first connecting line 311 and the cross-sectional shape of the second connecting line 321 are circular, and the second diameter r of the second connecting line 321 is... n The first diameter r1 is smaller than that of the first connecting line 311.

[0115] The equivalent inductance L11 of the first connecting line 311 is shown in the following formula (6):

[0116] The equivalent inductance Ln1 of the second connecting line 321 is shown in the following formula (7):

[0117] The first length w1 of the first connecting line 311 is greater than the second length w of the second connecting line 321. n By reducing the second diameter r of the second connecting line 321 n So that the second diameter r of the second connecting line 321 n The difference between the equivalent inductance L11 of the first connecting line 311 and the equivalent inductance Ln1 of the second connecting line 321 is less than a preset threshold. For example, the second length w of the second connecting line 321 is less than the first diameter r1 of the first connecting line 311. n If the first length w1 of the first connecting line 311 is half of the first length w1, then the second diameter r of the second connecting line 321 is... n The value is half the first diameter r1 of the first connecting line 311, so that the equivalent inductance L11 of the first connecting line 311 is close to the same as the equivalent inductance Ln1 of the second connecting line 321.

[0118] According to some embodiments of this application, as shown in FIG6, the first connecting line 311 includes a first sub-connecting line 3111 and a second sub-connecting line 3112 arranged in parallel with the first sub-connecting line 3111, and the second connecting line 321 includes a third sub-connecting line 3211 and a fourth sub-connecting line 3212 arranged in parallel with the third sub-connecting line 3211; the first spacing between the first sub-connecting line 3111 and the second sub-connecting line 3112 is configured to adjust the equivalent inductance of the first connecting line 311, and the second spacing between the third sub-connecting line 3211 and the fourth sub-connecting line 3212 is configured to adjust the equivalent inductance of the second connecting line 321.

[0119] In some embodiments, the first sub-connecting line 3111 and the second sub-connecting line 3112 are arranged side by side, and the direction of the current flowing through the first sub-connecting line 3111 is opposite to the direction of the current flowing through the second sub-connecting line 3112. The third sub-connecting line 3211 and the fourth sub-connecting line 3212 are arranged side by side, and the direction of the current flowing through the third sub-connecting line 3211 is opposite to the direction of the current flowing through the fourth sub-connecting line 3212. In this way, the mutual inductance between the first and second sub-connecting lines, as well as the mutual inductance between the third and fourth sub-connecting lines, can be increased, thereby reducing the equivalent inductance of the first connecting line and the equivalent inductance of the second connecting line, and thus reducing the difference between the equivalent inductance of the first connecting line and the equivalent inductance of the second connecting line.

[0120] For example, the first sub-connection line 3111 can be the positive connection line between the first energy storage unit 31 and the power conversion circuit 10, the second sub-connection line 3112 can be the negative connection line between the first energy storage unit 31 and the power conversion circuit 10, the third sub-connection line 3211 can be the positive connection line between the second energy storage unit 32 and the power conversion circuit 10, and the fourth sub-connection line 3212 can be the negative connection line between the second energy storage unit 32 and the power conversion circuit 10.

[0121] In some embodiments, the cross-sectional shapes of the first sub-connecting line 3111, the second sub-connecting line 3112, the third sub-connecting line 3211, and the fourth sub-connecting line 3212 are all circular. The formula for calculating the mutual inductance between the first sub-connecting line 3111 and the second sub-connecting line 3112, and the mutual inductance between the third sub-connecting line 3211 and the fourth sub-connecting line 3212 is M=k*(L3L4)1 / 2, where L3 and L4 are the self-inductance of the first sub-connecting line 3111 and the second sub-connecting line 3112 or the self-inductance of the third sub-connecting line 3211 and the fourth sub-connecting line 3212. The value of M increases with the first gap between the first sub-connecting line 3111 and the second sub-connecting line 3112 or the second gap between the third sub-connecting line 3211 and the fourth sub-connecting line 3212. That is, the smaller the first gap or the second gap, the greater the mutual inductance between the first sub-connecting line 3111 and the second sub-connecting line 3112 or the mutual inductance between the third sub-connecting line 3211 and the fourth sub-connecting line 3212.

[0122] When the first sub-connecting line 3111 and the second sub-connecting line 3112, or the third sub-connecting line 3211 and the fourth sub-connecting line 3212, are arranged in parallel and the current directions are opposite, the equivalent inductance of the first connecting line 311 is equal to the inductance of the first connecting line 311 minus the mutual inductance between the first sub-connecting line 3111 and the second sub-connecting line 3112; the equivalent inductance of the second connecting line 321 is equal to the inductance of the second connecting line 321 minus the mutual inductance between the third sub-connecting line 3211 and the fourth sub-connecting line 3212. Specifically, the inductance of the first connecting line 311 is equal to the sum of the equivalent inductances of the first sub-connecting line 3111 and the second sub-connecting line 3112, and the inductance of the second connecting line 321 is equal to the sum of the equivalent inductances of the third sub-connecting line 3211 and the fourth sub-connecting line 3212. The equivalent inductance of the first sub-connection line 3111, the second sub-connection line 3112, the third sub-connection line 3211, and the fourth sub-connection line 3212 can be calculated using the formulas described in the above embodiments.

[0123] Understandably, the first spacing between the first sub-connection line 3111 and the second sub-connection line 3112 is configured to adjust the equivalent inductance of the first connection line 311. That is, the equivalent inductance of the first connection line 3111 can be adjusted by adjusting the first spacing between the first sub-connection line 3111 and the second sub-connection line 3112. For example, increasing the first spacing between the first sub-connection line 3111 and the second sub-connection line 3112 increases the equivalent inductance of the first connection line 311, or decreasing the first spacing between the first sub-connection line 3111 and the second sub-connection line 3112 decreases the equivalent inductance of the first connection line 311. The second spacing between the third sub-connection line 3211 and the fourth sub-connection line 3212 is configured to adjust the equivalent inductance of the second connection line 321. That is, the equivalent inductance of the second connection line 321 can be adjusted by adjusting the second spacing between the third sub-connection line 3211 and the fourth sub-connection line 3212.

[0124] In other embodiments, the cross-sectional shapes of the first sub-connecting line 3111, the second sub-connecting line 3112, the third sub-connecting line 3211, and the fourth sub-connecting line 3212 are all rectangular.

[0125] In this embodiment of the application, the first spacing between the first sub-connecting line 3111 and the second sub-connecting line 3112 is configured to adjust the equivalent inductance of the first connecting line 311, and the second spacing between the third sub-connecting line 3211 and the fourth sub-connecting line 3212 is configured to adjust the equivalent inductance of the second connecting line 321. By adjusting the first spacing and the second spacing, the difference between the equivalent inductance of the first connecting line 311 and the equivalent inductance of the second connecting line 321 can be made less than a preset threshold.

[0126] According to some embodiments of this application, when the first length of the first connecting line 311 is less than the second length of the second connecting line 312, the first spacing is greater than the second spacing.

[0127] In some embodiments, when the first length of the first connecting line 311 is less than the second length of the second connecting line 321, that is, when the length of the first sub-connecting line 3111 is equal to the length of the second sub-connecting line 3112, the length of the third sub-connecting line 3211 is equal to the length of the fourth sub-connecting line 3212, and the length of the first sub-connecting line 3111 is less than the length of the third sub-connecting line 3211; the first spacing between the first sub-connecting line 3111 and the second sub-connecting line 3112 is greater than the second spacing between the third sub-connecting line 3211 and the fourth sub-connecting line 3212.

[0128] In some embodiments, the cross-sectional area of ​​the first connecting line 311 is equal to the cross-sectional area of ​​the second connecting line 321, that is, the cross-sectional areas of the first sub-connecting line 3111, the second sub-connecting line 3112, the third sub-connecting line 3211, and the fourth sub-connecting line 3212 are equal. Thus, by setting the cross-sectional areas of the first connecting line and the second connecting line to be equal, based on the first length of the first connecting line being equal to the second length of the second connecting line, the consistency between the equivalent inductance of the first connecting line and the equivalent inductance of the second connecting line can be further improved, reducing the risk of over-limit current generation in the first and second energy storage units during the switching of the energy storage valve submodule into and out of the module.

[0129] When the length of the first sub-connecting line 3111 is less than the length of the third sub-connecting line 3211, according to formula (1), the equivalent inductance of the first connecting line 311 is less than the equivalent inductance of the second connecting line 321. By setting the first gap between the first sub-connecting line 3111 and the second sub-connecting line 3112 to be greater than the second gap between the third sub-connecting line 3211 and the fourth sub-connecting line 3212.

[0130] In some embodiments, the first spacing between the first sub-connecting line 3111 and the second sub-connecting line 3112 is increased so that the first spacing is greater than the second spacing. According to the mutual inductance calculation formula, the mutual inductance between the first sub-connecting line 3111 and the second sub-connecting line 3112 is reduced by increasing the first spacing, thereby increasing the equivalent inductance of the first connecting line 311. This makes the difference between the equivalent inductance of the first connecting line 311 and the equivalent inductance of the second connecting line 321 less than a preset threshold.

[0131] In some embodiments, the second spacing between the third sub-connecting line 3211 and the fourth sub-connecting line 3212 is reduced so that the first spacing is greater than the second spacing. According to the mutual inductance calculation formula, the mutual inductance between the third sub-connecting line 3211 and the fourth sub-connecting line 3212 is increased by reducing the second spacing, thereby reducing the equivalent inductance of the second connecting line 321. This makes the difference between the equivalent inductance of the first connecting line 311 and the equivalent inductance of the second connecting line 321 less than a preset threshold.

[0132] In some embodiments, the first spacing between the first sub-connecting line 3111 and the second sub-connecting line 3112 is increased, while the second spacing between the third sub-connecting line 3211 and the fourth sub-connecting line 3212 is reduced, so that the mutual inductance between the first sub-connecting line 3111 and the second sub-connecting line 3112 is reduced, and the mutual inductance between the third sub-connecting line 3211 and the fourth sub-connecting line 3212 is increased, so that the difference between the equivalent inductance of the first connecting line 311 and the equivalent inductance of the second connecting line 321 is less than a preset threshold.

[0133] When the first length of the first connecting line 311 is less than the second length of the second connecting line 321, the equivalent inductance of the second connecting line 321 is greater than the equivalent inductance of the first connecting line 311. The mutual inductance between the first sub-connecting line 3111 and the second sub-connecting line 3112 is related to the first spacing, and the mutual inductance between the third sub-connecting line 3211 and the fourth sub-connecting line 3212 is related to the second spacing. By making the first spacing greater than the second spacing, the mutual inductance between the first sub-connecting line 3111 and the second sub-connecting line 3112 is less than the mutual inductance between the third sub-connecting line 3211 and the fourth sub-connecting line 3212. This adjusts the equivalent inductance of the second connecting line 321 and the equivalent inductance of the first connecting line 311, enabling the difference between the equivalent inductance of the first connecting line 311 and the equivalent inductance of the second connecting line 321 to be less than a preset threshold.

[0134] According to some embodiments of this application, the cross-sectional area of ​​the first sub-connecting line 3111 is smaller than the cross-sectional area of ​​the third sub-connecting line 3211; and / or, the cross-sectional area of ​​the second sub-connecting line 3112 is smaller than the cross-sectional area of ​​the fourth sub-connecting line 3212.

[0135] When the cross-sectional area of ​​the first connecting line 311 is not equal to the cross-sectional area of ​​the second connecting line 321, the equivalent inductance of the first connecting line 311 is less than the equivalent inductance of the second connecting line 321, and the first gap is greater than the second gap.

[0136] In some embodiments, the cross-sectional area of ​​the first sub-connecting line 3111 is the same as the cross-sectional area of ​​the second sub-connecting line 3112, and the cross-sectional areas of the third sub-connecting line 3211 and the fourth sub-connecting line 3212 are the same. The cross-sectional area of ​​the first sub-connecting line 3111 is different from the cross-sectional area of ​​the third sub-connecting line 3211. The cross-sectional area of ​​the first sub-connecting line 3111 is smaller than the cross-sectional area of ​​the third sub-connecting line 3211, and the cross-sectional area of ​​the second sub-connecting line 3112 is smaller than the cross-sectional area of ​​the fourth sub-connecting line 3212.

[0137] When the lengths of the first sub-connecting line 3111, the second sub-connecting line 3112, the third sub-connecting line 3211, and the fourth sub-connecting line 3212 are equal, the first spacing is greater than the second spacing. The cross-sectional area of ​​the first sub-connecting line 3111 is less than the cross-sectional area of ​​the third sub-connecting line 3211, and the cross-sectional area of ​​the second sub-connecting line 3112 is less than the cross-sectional area of ​​the fourth sub-connecting line 3212. According to formula (1), the equivalent inductance of the first sub-connecting line 3111 and the equivalent inductance of the second sub-connecting line 3112 can be reduced, thereby reducing the equivalent inductance of the first connecting line 311 and realizing that the difference between the equivalent inductance of the first connecting line 311 and the equivalent inductance of the second connecting line 321 is less than a preset threshold.

[0138] In some embodiments, the cross-sectional areas of the first sub-connecting line 3111 and the second sub-connecting line 3112 are different, the cross-sectional areas of the third sub-connecting line 3211 and the fourth sub-connecting line 3212 are different, and the cross-sectional areas of the first sub-connecting line 3111 and the third sub-connecting line 3211 are different. The cross-sectional area of ​​the first sub-connecting line 3111 is smaller than the cross-sectional area of ​​the third sub-connecting line 3211, or the cross-sectional area of ​​the second sub-connecting line 3112 is smaller than the cross-sectional area of ​​the fourth sub-connecting line 3212. According to formula (1), the equivalent inductance of the first sub-connecting line 3111 or the equivalent inductance of the second sub-connecting line 3112 can be reduced, thereby reducing the equivalent inductance of the first connecting line 311, and realizing that the difference between the equivalent inductance of the first connecting line 311 and the equivalent inductance of the second connecting line 321 is less than a preset threshold.

[0139] In this embodiment, by using a first spacing greater than a second spacing, when the mutual inductance between the first sub-connecting line 3111 and the second sub-connecting line 3112 is less than the mutual inductance between the third sub-connecting line 3211 and the fourth sub-connecting line 3212, the equivalent inductance of the first connecting line 311 is related to the cross-sectional area of ​​the first sub-connecting line 3111 and / or the cross-sectional area of ​​the second sub-connecting line 3112, and the equivalent inductance of the second connecting line 321 is related to the cross-sectional area of ​​the third sub-connecting line 3211 and / or the cross-sectional area of ​​the fourth sub-connecting line 3212. By adjusting the equivalent inductance of the second connecting line 321 and the equivalent inductance of the first connecting line 311, the difference between the equivalent inductance of the first connecting line 311 and the equivalent inductance of the second connecting line 321 can be made less than a preset threshold.

[0140] According to some embodiments of this application, both the first connecting line 311 and the second connecting line 321 are cables.

[0141] The first connecting line 311 and the second connecting line 321 are both cables. One cable connects the first energy storage unit 31 to the power conversion circuit 10, and the other cable connects the second energy storage unit 32 to the power conversion circuit 10.

[0142] A small spacing between the positive and negative wires in a cable increases the mutual inductance between them. For example, the small spacing between the first sub-connecting wire 3111 (e.g., positive wire) and the second sub-connecting wire 3112 (e.g., negative wire) in the first connecting wire 311, and the small second spacing between the third sub-connecting wire 3211 and the fourth sub-connecting wire 3212 in the second connecting wire 321, increases the mutual inductance between the first sub-connecting wire 3111 and the second sub-connecting wire 3112 in the first connecting wire 311, and increases the mutual inductance between the third sub-connecting wire 3211 and the fourth sub-connecting wire 3212 in the second connecting wire 321, thereby reducing the equivalent inductance of the first connecting wire 311 and the equivalent inductance of the second connecting wire 321.

[0143] In this embodiment, by setting both the first connecting line 311 and the second connecting line 321 to be cables, and the small spacing between the positive and negative lines in the cables, the mutual inductance between the positive and negative lines in the cables is increased, thereby reducing the equivalent inductance of the first connecting line 311 and the equivalent inductance of the second connecting line 321. This enables the difference between the equivalent inductance of the first connecting line 311 and the equivalent inductance of the second connecting line 321 to be less than a preset threshold.

[0144] According to some embodiments of this application, as shown in FIG7, the power conversion circuit 10 is located spatially between the first energy storage unit 31 and the second energy storage unit 32.

[0145] The first energy storage unit 31 is connected to the power conversion circuit 10 via a first connecting line 311, and the second energy storage unit 32 is connected to the power conversion circuit 10 via a second connecting line 321. The power conversion circuit 10 is positioned in a spatial location between the first energy storage unit 31 and the second energy storage unit 32. The spatial location refers to the actual placement of the power conversion circuit 10, the first energy storage unit 31, and the second energy storage unit 32 in specific applications.

[0146] In one embodiment, the first energy storage unit 31 and the second energy storage unit 32 are located on the same side of the power conversion circuit 10. Assuming the second energy storage unit 32 is farther from the first energy storage unit 31 than the power conversion circuit 10, the distance between the second energy storage unit 32 and the power conversion circuit 10 is greater than the distance between the first energy storage unit 31 and the power conversion circuit 10. By positioning the power conversion circuit 10 between the first energy storage unit 31 and the second energy storage unit 32 in the spatial location, the distance between the second energy storage unit 32 and the power conversion circuit 10 can be made similar to or equal to the distance between the first energy storage unit 31 and the power conversion circuit 10, thus reducing the difference between the distance between the first energy storage unit 31 and the power conversion circuit 10 and the distance between the second energy storage unit 32 and the power conversion circuit 10.

[0147] In this embodiment, by positioning the power conversion circuit 10 between the first energy storage unit 31 and the second energy storage unit 32 in spatial location, the difference between the distance between the first energy storage unit 31 and the power conversion circuit 10 and the distance between the second energy storage unit 32 and the power conversion circuit 10 is reduced, that is, the difference between the length of the first connecting line 311 and the length of the second connecting line 321 is reduced, so that the difference between the equivalent inductance of the first connecting line 311 and the equivalent inductance of the second connecting line 321 is less than a preset threshold.

[0148] According to some embodiments of this application, as shown in FIG8, the energy storage valve submodule further includes an isolating switch unit connected between the first energy storage unit 31 and the first capacitor 20.

[0149] The isolating switch unit may include switches Q1 and Q2, which are connected between the first energy storage unit 31 and the first capacitor 20. For example, one end of the first capacitor 20 is connected to the positive terminal of the first energy storage unit 31 via switch Q1, and the other end of the first capacitor 20 is connected to the negative terminal of the first energy storage unit 31 via switch Q2. The connection between the first energy storage unit 31 and the first capacitor 20 is controlled by the on / off state of switches Q1 and Q2, thereby controlling the on / off state of the first energy storage unit 31 and the power conversion circuit 10. When switches Q1 and Q2 are off, the first energy storage unit 31 is disconnected from the power conversion circuit 10; when switches Q1 and Q2 are on, the first energy storage unit 31 is connected to the power conversion circuit 10.

[0150] It should be noted that Figure 8 only shows the disconnecting switch unit connected between the first energy storage unit 31 and the first capacitor 20. In practical applications, the disconnecting switch unit can also be connected between the second energy storage unit 32 and the first capacitor 20 simultaneously, that is, the conduction status of the first energy storage unit 31 and the second energy storage unit 32 can be controlled through the disconnecting switch unit.

[0151] In this embodiment, an isolating switch unit is connected between the first energy storage unit 31 and the first capacitor 20. The isolating switch unit controls the on / off state of the first energy storage unit 31 to protect the first energy storage unit 31 and enable the energy storage valve submodule to work stably.

[0152] According to some embodiments of this application, as shown in FIG9, the energy storage valve submodule further includes a resistor element 21, which is connected in series with the first capacitor 20.

[0153] In the energy storage valve submodule, a resistor element 21 is connected in series on the branch where the first capacitor 20 is located, forming a RC branch. The RC branch is connected in parallel with the power conversion circuit 10 and the first energy storage unit 31.

[0154] In some embodiments, referring further to FIG9, the energy storage valve submodule also includes a second capacitor 40, which is connected in parallel with the RC branch. Thus, since the second capacitor is connected in parallel with the RC branch, it can be used to buffer the high-frequency current in the current of the energy storage valve submodule at the time of activation, thereby reducing the rate of change of the turn-off current at the time of switch-off and reducing the overvoltage stress at the time of switch-off.

[0155] It is understood that the connection method of the second capacitor 40 shown in Figure 9 is only an example. In practical applications, the second capacitor 40 can be connected in parallel between the RC branch and the power conversion circuit 10 as shown in Figure 9; or it can be connected in parallel between the RC branch and the first energy storage unit 31, etc.

[0156] The second capacitor 40 includes a buffer capacitor. The main function of the second capacitor 40 in the energy storage valve submodule is to buffer the high-frequency current in the current of the energy storage valve submodule at the time of activation, so as to reduce the rate of change of the turn-off current at the time of IGBT turn-off, thereby reducing the overvoltage stress at the time of IGBT turn-off.

[0157] In this embodiment, a resistor element 21 is connected in series on the branch where the first capacitor 20 is located to form a RC branch. The resistor element 21 provides the resistance value required to suppress the underdamped oscillating current generated by the energy storage valve submodule at the time of commissioning. This is not only economical and convenient, but also greatly reduces the additional impact on the overall function of the energy storage valve submodule and further increases the stability of the energy storage valve submodule.

[0158] According to some embodiments of this application, as shown in FIG9, the energy storage valve submodule further includes a bypass circuit 50, which is connected in parallel with the energy storage valve submodule.

[0159] One end of the bypass circuit 50 is connected to port S1 of the energy storage valve submodule, and the other end of the bypass circuit 50 is connected to port S2 of the energy storage valve submodule. The bypass circuit 50 is used to disconnect the energy storage valve submodule from the high-voltage direct-connected energy storage system in the event of a fault in the energy storage valve submodule, or in the event that the energy storage valve submodule may fail.

[0160] For example, when an overvoltage occurs in the high-voltage direct-connected energy storage system, the bypass circuit 50 can conveniently and promptly disconnect the energy storage valve submodule from the high-voltage direct-connected energy storage system, thereby significantly reducing the probability of the energy storage valve submodule failing due to the overvoltage generated by the high-voltage direct-connected energy storage system, thus improving the operational stability and safety of the high-voltage direct-connected energy storage system.

[0161] In some embodiments, the bypass circuit 50 may be a bypass switch, which may be, in some embodiments, a mechanical bypass switch or a semiconductor device bypass switch, but is not limited to.

[0162] In the event of a fault in the energy storage valve submodule, current enters the main circuit from port S1. At this time, the bypass switch closes, and the current flows out from port S2 through the bypass switch, completely short-circuiting the entire energy storage valve submodule and thus completely disconnecting the energy storage valve submodule from the high-voltage direct-connected energy storage system.

[0163] In this embodiment, by setting a bypass circuit 50 between the ports of the energy storage valve submodule connected to the main circuit of the high-voltage direct-connected energy storage system, the energy storage valve submodule can be disconnected from the high-voltage direct-connected energy storage system in the event of a fault in the energy storage valve submodule, thereby improving the operational stability and safety of the high-voltage direct-connected energy storage system.

[0164] In some embodiments, the input current of the energy storage valve submodule includes a stepped wave. Thus, in scenarios where the input current of the energy storage valve submodule includes a stepped wave, since the stepped wave may cause the first energy storage unit and / or the second energy storage unit to generate over-limit currents, by setting the difference between the equivalent inductance of the first connection line and the equivalent inductance of the second connection line to be less than a preset threshold, i.e., the equivalent inductance of the first energy storage unit and the equivalent inductance of the second energy storage unit are approximately the same, the current in the first energy storage unit and the current in the second energy storage unit can be made approximately the same at the step time, thereby suppressing the generation of over-limit currents in the first and second energy storage units at the step time, thus reducing damage to the first and second energy storage units and improving the stability and reliability of the energy storage valve submodule.

[0165] In some embodiments, as shown in FIG10, the energy storage valve submodule further includes a connecting busbar 60, and the first connecting line 311 and the second connecting line 321 are both connected to the power conversion circuit 10 through the connecting busbar 60.

[0166] Here, the connection path of the busbar 60 can be any suitable path, and this application embodiment does not limit it.

[0167] In some embodiments, the first connecting line 311 and the second connecting line 321 can be copper bars, that is, the first energy storage unit 31 and the second energy storage unit 32 can both be welded to the connecting busbar 60 through copper bars.

[0168] The connecting busbar 60 is a power busbar with high current carrying capacity in the circuit connection, and can be used as a main transmission line to connect with several branch lines. The branch lines may include connecting lines from each energy storage unit to the connecting busbar 60. For example, the first energy storage unit 31 can be connected to the connecting busbar 60 through the first connecting line 311, and the second energy storage unit 32 can be connected to the connecting busbar 60 through the second connecting line 321.

[0169] In implementation, the connecting busbar 60 can be made of, but is not limited to, copper or aluminum. The cross-section of the connecting busbar 60 (perpendicular to its extension direction) can be approximately rectangular or grooved. Furthermore, the surface of the connecting busbar 60 can be insulated to reduce the risk of leakage; for example, the surface of the connecting busbar 60 can be coated with an insulating layer or bonded with insulating adhesive.

[0170] Understandably, since the connecting busbar has a strong current carrying capacity and its equivalent inductance is usually low, both the first and second connecting lines are connected to the power conversion circuit through the connecting busbar. This can reduce the equivalent inductance of the current transmission path between the first energy storage unit and the power conversion circuit, and also reduce the equivalent inductance of the current transmission path between the second energy storage unit and the power conversion circuit. As a result, the equivalent inductance of the current transmission path between the first energy storage unit and the power conversion circuit, and the equivalent inductance of the current transmission path between the second energy storage unit and the power conversion circuit, can be made to be nearly the same. This helps to suppress the generation of over-limit current in the first and second energy storage units at the switching moments when the energy storage valve submodule is put into and taken out.

[0171] In some embodiments, the current transmission path between the power conversion circuit 10 and the first energy storage unit 31 on the connecting busbar 60 has a third length, and the current transmission path between the power conversion circuit 10 and the second energy storage unit 32 on the connecting busbar has a fourth length, and the difference between the third length and the fourth length is less than a preset length threshold.

[0172] Here, the preset length threshold can be a small pre-set length threshold. By setting the difference between the third length and the fourth length to be less than the preset length threshold, the third length and the fourth length can be made to approach equal length.

[0173] In some implementations, the preset length threshold can be a second preset percentage of the average of the sum of the third length and the fourth length. For example, the range of the second preset percentage is between 5% and 15%, that is, the second preset percentage can be 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, or 15%, etc.

[0174] In some implementations, the preset length threshold can be a second preset ratio of the third length or the fourth length, for example, the preset length threshold is 10% of the third length. Another example is that the preset length threshold is 5% of the fourth length.

[0175] In the technical solution of this application embodiment, the difference between the third length and the fourth length is less than a preset length threshold, that is, the transmission path length of the current between the power conversion circuit and the first energy storage unit on the connecting busbar and the transmission path length of the current between the power conversion circuit and the second energy storage unit on the connecting busbar are approximately equal, thereby making the equivalent inductance of the current transmission path between the first energy storage unit and the power conversion circuit and the equivalent inductance of the current transmission path between the second energy storage unit and the power conversion circuit approximately the same.

[0176] In some embodiments, as shown in FIG11, the connecting bus 60 includes a first connecting bus 61 and a second connecting bus 62. The first connecting bus 61 is connected to the positive terminal of the first energy storage unit 31 and the positive terminal of the second energy storage unit 32, and is connected to the positive terminal of the power conversion circuit 10 through a first bus point 611. The second connecting bus 62 is connected to the negative terminal of the first energy storage unit 31 and the negative terminal of the second energy storage unit 32, and is connected to the negative terminal of the power conversion circuit 10 through a second bus point 621. The first bus point 61 and the second bus point 62 are located spatially between the first energy storage unit 31 and the second energy storage unit 32.

[0177] Here, the first junction point 61 and the second junction point 62 can be set at any suitable location between the first energy storage unit 31 and the second energy storage unit 32, and this embodiment does not limit this.

[0178] In some embodiments, the path from the positive electrode of the first energy storage unit 31 to the first junction point 61 is similar in length to or equal to the path from the positive electrode of the second energy storage unit 32 to the first junction point 61; the path from the positive electrode of the first energy storage unit 31 to the second junction point 62 is similar in length to or equal to the path from the positive electrode of the second energy storage unit 32 to the second junction point 62.

[0179] In the technical solution of this application embodiment, the first connecting bar connecting the positive terminal of the first energy storage unit and the positive terminal of the second energy storage unit is connected to the positive terminal of the power conversion circuit through the first bus point. The second connecting bar connecting the negative terminal of the first energy storage unit and the negative terminal of the second energy storage unit is connected to the negative terminal of the power conversion circuit through the second bus point. Since the first bus point and the second bus point are located between the first energy storage unit and the second energy storage unit in spatial position, the difference in distance between the positive terminal of the first energy storage unit and the positive terminal of the second energy storage unit to the first bus point can be reduced, and the difference in distance between the negative terminal of the first energy storage unit and the negative terminal of the second energy storage unit to the second bus point can also be reduced. That is, the difference between the equivalent inductance of the current transmission path between the first energy storage unit and the power conversion circuit and the equivalent inductance of the current transmission path between the second energy storage unit and the power conversion circuit can be reduced.

[0180] In some embodiments, as shown in FIG12, the energy storage valve submodule further includes an inductor 70, and the first connecting line 311 and the second connecting line 321 are both connected to the power conversion circuit 10 through the inductor 70.

[0181] Here, one end of the inductor 70 is connected to the power conversion circuit 10, and the other end is connected to the first connection line 311 and the second connection line 321.

[0182] In some embodiments, one end of the inductor 70 is connected to the power conversion circuit 10 and the first capacitor 20, and the other end is connected to the first connection line 311 and the second connection line 321.

[0183] The inductance value of the inductor 70 can be set according to actual conditions, and this embodiment does not limit it. For example, the inductance value of the inductor 70 can be greater than the equivalent inductance of the first connecting line 311 and greater than the equivalent inductance of the second connecting line 321.

[0184] The inductor 70 can be placed on the positive side of the power conversion circuit 10 or on the negative side of the power conversion circuit 10; there is no limitation on this.

[0185] In the technical solution of this application embodiment, by setting both the first connecting line and the second connecting line to be connected to the power conversion circuit through the inductor element, the same inductance can be introduced into the current transmission path between the first energy storage unit and the power conversion circuit, as well as the current transmission path between the second energy storage unit and the power conversion circuit. This reduces the impact of the difference between the equivalent inductance of the first energy storage unit and the equivalent inductance of the second energy storage unit during the underdamped oscillation process. As a result, at the switching moment when the energy storage valve submodule is put into and taken out, the current between the first energy storage unit and the power conversion circuit and the current between the second energy storage unit and the power conversion circuit tend to be consistent, thereby reducing the risk of the first energy storage unit and the second energy storage unit generating over-limit current.

[0186] In some embodiments, the inductance value of the inductor 70 is greater than a preset multiple of the target inductance value, where the target inductance value is the average of the equivalent inductance of the first connecting line 311 and the equivalent inductance of the second connecting line 321. The preset multiple can be greater than 1; for example, the value of the preset multiple can be between 1 and 10.

[0187] In some implementations, the preset multiple is 5, meaning that the inductance value of the inductor 70 is greater than 5 times the target inductance value.

[0188] In some embodiments, the energy storage valve submodule includes multiple energy storage units. One end of the inductor 70 is connected to the power conversion circuit 10, and the other end is connected to the corresponding connection line of each energy storage unit. The target inductance value is the average value among the equivalent inductances of the corresponding connection lines of each energy storage unit. The inductance value of the inductor 70 is greater than a preset multiple of the target inductance value.

[0189] In the technical solution of this application embodiment, the inductance value of the inductor is greater than a preset multiple of the average value between the equivalent inductance of the first connecting line and the equivalent inductance of the second connecting line. This can further reduce the influence of the difference between the equivalent inductance of the first energy storage unit and the equivalent inductance of the second energy storage unit during the underdamped oscillation process, thereby further reducing the risk of the first energy storage unit and the second energy storage unit generating over-limit current.

[0190] In some embodiments, as shown in FIG13, the energy storage valve submodule further includes a clamping circuit 80, which is connected in parallel between the RC branch and the first energy storage unit 31. The clamping circuit 80 is used to clamp the voltage of the first energy storage unit 31 within a set voltage range. For example, the clamping circuit 80 may include, but is not limited to, a clamping diode, a transient voltage suppressor (TVS), etc.

[0191] For ease of understanding, the energy storage valve submodule using cable connection in this application embodiment is described by way of example. A simulation circuit model is built using finite element simulation software (e.g., Space Claim), creating two 95mm... 2 The cable model has a diameter of 11mm, a length of 2m, and a spacing of 50mm. The cross-sections on the same side of the two cables are set as excitation sources Source1 and Source2 (i.e., the step current source excitation mentioned above), and the corresponding cross-sections are set as Sink1 and Sink2.

[0192] The simulation results show that there is mutual inductance between cable 1 and cable 2. When the current in cable 1 (e.g., the first sub-connector 3111 or the third sub-connector 3211) and cable 2 (e.g., the second sub-connector 3112 or the fourth sub-connector 3212) are in the same direction and the spacing is set to 50mm, the inductance value can be, for example, the 2*2 matrix in Table 1 below.

[0193] Table 1. Inductance of two cables with current in the same direction (50mm spacing)

[0194] The total inductance of cable 1 and cable 2 is 7.38 μH, which is the sum of all values ​​in the matrix. For example, if the currents in the first sub-connector 3111 and the second sub-connector 3112 are in the same direction, the sum of the equivalent inductances of the first sub-connector 3111 and the second sub-connector 3112 is 7.38 μH. Alternatively, if the currents in the third sub-connector 3211 and the fourth sub-connector 3212 are in the same direction, the sum of the equivalent inductances of the third sub-connector 3211 and the fourth sub-connector 3212 is 7.38 μH.

[0195] When the current in cables 1 and 2 is in the same direction and the spacing is set to 25mm, the inductance value can be, for example, the 2*2 matrix in Table 2 below.

[0196] Table 2 Inductance of dual cables with current in the same direction (spacing 25mm)

[0197] The total inductance of cable 1 and cable 2 is 4.05 μH, which is the sum of all values ​​in the matrix. For example, by reducing the first spacing between the first sub-connection line 3111 and the second sub-connection line 3112, the sum of the equivalent inductance of the first sub-connection line 3111 and the equivalent inductance of the second sub-connection line 3112 is 4.05 μH; or by reducing the second spacing between the third sub-connection line 3211 and the fourth sub-connection line 3212, the sum of the equivalent inductance of the third sub-connection line 3211 and the equivalent inductance of the fourth sub-connection line 3212 is 4.05 μH.

[0198] Comparing Table 1, it can be seen that for cables 1 and 2 with the same current direction, their mutual inductance is superimposed. When the distance decreases, the mutual inductance of cables 1 and 2 increases, and the sum of the equivalent inductance of cable 1 and cable 2 decreases.

[0199] Furthermore, based on the above cable model, the input and output positions of the excitation source are adjusted, and the cross sections on the same side of the two cables are set as Source1 and Sink2 respectively, and the corresponding cross sections on the other side are set as Sink2 and Source1.

[0200] When the currents of cable 1 and cable 2 are reversed and the spacing is set to 50mm, the inductance value can be, for example, the 2*2 matrix in Table 3 below.

[0201] Table 3 Inductance of dual cables when current is reversed (50mm spacing)

[0202] The total inductance of cable 1 and cable 2 is 1.9 μH, which is the sum of all values ​​in the matrix. For example, the sum of the equivalent inductance of the first sub-connection 3111 and the equivalent inductance of the second sub-connection 3112 is 1.9 μH, or the sum of the equivalent inductance of the third sub-connection 3211 and the equivalent inductance of the fourth sub-connection 3212 is 1.9 μH.

[0203] When the currents of cable 1 and cable 2 are reversed and the spacing is set to 25mm, the inductance value can be, for example, the 2*2 matrix in Table 4 below.

[0204] Table 4. Inductance of two cables with current in the same direction (spacing 25mm)

[0205] The total inductance of cables 1 and 2 is 1.18 μH, which is the sum of all values ​​in the matrix. For example, by reducing the first spacing, the sum of the equivalent inductance of the first sub-connector 3111 and the equivalent inductance of the second sub-connector 3112 is 1.18 μH; or by reducing the second spacing, the sum of the equivalent inductance of the third sub-connector 3211 and the equivalent inductance of the fourth sub-connector 3212 is 1.18 μH.

[0206] Comparing Tables 1-4, for cables 1 and 2 with opposite current directions, their mutual inductance cancels each other out. When the distance between them decreases, the mutual inductance between cables 1 and 2 increases, and the sum of the equivalent inductance of cable 1 and cable 2 decreases.

[0207] Therefore, in this embodiment of the application, by adjusting the first spacing between the first sub-connecting line 3111 and the second sub-connecting line 3112, and / or adjusting the second spacing between the third sub-connecting line 3211 and the fourth sub-connecting line 3212, the difference between the equivalent inductance of the first connecting line 311 and the equivalent inductance of the second connecting line 321 can be less than a preset threshold. For example, when multiple cables are arranged in a circuit, the current direction of each cable can be analyzed, and by changing the gap between them, the spacing between cables with the same current direction can be increased, and the spacing between cables with the opposite current direction can be decreased, thereby optimizing the total circuit inductance value.

[0208] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims. Industrial applicability

[0209] This application provides an energy storage valve submodule and a high-voltage direct-connected energy storage system. The energy storage valve submodule includes a power conversion circuit, a first capacitor, a first energy storage unit, and a second energy storage unit. The first capacitor, the first energy storage unit, and the second energy storage unit are all connected in parallel with the power conversion circuit. A first connection line connects the first energy storage unit to the power conversion circuit, and a second connection line connects the second energy storage unit to the power conversion circuit. The difference between the equivalent inductance of the first connection line and the equivalent inductance of the second connection line is less than a preset threshold. This application can suppress the generation of over-limit current in the first and second energy storage units during the switching between the activation and deactivation of the energy storage valve submodule, thereby reducing damage to the first and second energy storage units and improving the stability and reliability of the energy storage valve submodule.

Claims

1. An energy storage valve submodule, the energy storage valve submodule comprising a power conversion circuit, a first capacitor, a first energy storage unit and a second energy storage unit, wherein the first capacitor, the first energy storage unit and the second energy storage unit are all connected in parallel with the power conversion circuit, a first connection line between the first energy storage unit and the power conversion circuit, a second connection line between the second energy storage unit and the power conversion circuit, wherein the difference between the equivalent inductance of the first connection line and the equivalent inductance of the second connection line is less than a preset threshold.

2. The energy storage valve sub-module of claim 1, wherein, The first length of the first connecting line is equal to the second length of the second connecting line.

3. The energy storage valve sub-module of claim 2, wherein, The cross-sectional area of ​​the first connecting line is equal to the cross-sectional area of ​​the second connecting line.

4. The energy storage valve sub-module of claim 1, wherein, The first length of the first connecting line is less than the second length of the second connecting line, and the cross-sectional area of ​​the second connecting line is greater than the cross-sectional area of ​​the first connecting line.

5. The energy storage valve sub-module of claim 1, wherein, The first connecting line includes a first sub-connecting line and a second sub-connecting line arranged in parallel with the first sub-connecting line. The second connecting line includes a third sub-connecting line and a fourth sub-connecting line arranged in parallel with the third sub-connecting line. A first spacing between the first sub-connecting line and the second sub-connecting line is configured to adjust the equivalent inductance of the first connecting line, and a second spacing between the third sub-connecting line and the fourth sub-connecting line is configured to adjust the equivalent inductance of the second connecting line.

6. The energy storage valve sub-module of claim 5, wherein, When the first length of the first connecting line is less than the second length of the second connecting line, the first spacing is greater than the second spacing.

7. The energy storage valve sub-module of claim 6, wherein, The cross-sectional area of ​​the first sub-connecting line is smaller than the cross-sectional area of ​​the third sub-connecting line; and / or, the cross-sectional area of ​​the second sub-connecting line is smaller than the cross-sectional area of ​​the fourth sub-connecting line.

8. The energy storage valve sub-module of any of claims 5-7, wherein, The direction of the current flowing through the first sub-connecting line is opposite to the direction of the current flowing through the second sub-connecting line; the direction of the current flowing through the third sub-connecting line is opposite to the direction of the current flowing through the fourth sub-connecting line.

9. The energy storage valve sub-module of any of claims 1-8, wherein, Both the first connecting line and the second connecting line are cables.

10. The energy storage valve sub-module of any of claims 1-9, wherein, The power conversion circuit is located spatially between the first energy storage unit and the second energy storage unit.

11. The energy storage valve submodule according to any one of claims 1-10, wherein the energy storage valve submodule further comprises a resistive element, the resistive element being connected in series with the first capacitor.

12. The energy storage valve sub-module of claim 11, wherein, The first capacitor and the resistive element form a RC branch, and the energy storage valve submodule also includes a second capacitor, which is connected in parallel with the RC branch.

13. The energy storage valve submodule according to any one of claims 1-12, wherein the input current of the energy storage valve submodule comprises a stepped wave.

14. The energy storage valve submodule according to any one of claims 1-13, wherein the energy storage valve submodule further includes a connecting busbar, and the first connecting line and the second connecting line are both connected to the power conversion circuit through the connecting busbar.

15. The energy storage valve sub-module of claim 14, wherein, The current transmission path between the power conversion circuit and the first energy storage unit on the connecting busbar has a third length, and the current transmission path between the power conversion circuit and the second energy storage unit on the connecting busbar has a fourth length. The difference between the third length and the fourth length is less than a preset length threshold.

16. The energy storage valve sub-module of claim 14 or 15, wherein, The connecting busbar includes a first connecting busbar and a second connecting busbar. The first connecting busbar connects the positive terminals of the first energy storage unit and the second energy storage unit, and is connected to the positive terminal of the power conversion circuit through a first busbar. The second connecting busbar connects the negative terminals of the first energy storage unit and the second energy storage unit, and is connected to the negative terminal of the power conversion circuit through a second busbar. The first busbar and the second busbar are located spatially between the first energy storage unit and the second energy storage unit.

17. The energy storage valve submodule according to any one of claims 1-16, wherein the energy storage valve submodule further comprises an inductor, and both the first connecting line and the second connecting line are connected to the power conversion circuit through the inductor.

18. The energy storage valve sub-module of claim 17, wherein, The inductance value of the inductor is greater than a preset multiple of the target inductance value, and the target inductance value is the average value between the equivalent inductance of the first connecting line and the equivalent inductance of the second connecting line.

19. The energy storage valve submodule according to claims 1-18, wherein the energy storage valve submodule further comprises an isolating switch unit connected between the first energy storage unit and the first capacitor, and / or the isolating switch unit is connected between the second energy storage unit and the first capacitor.

20. A high-voltage direct-connected energy storage system, the high-voltage direct-connected energy storage system comprising a main circuit and an energy storage valve submodule as described in any one of claims 1-19, wherein two connection ports of each energy storage valve submodule are connected to the main circuit.

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