Energy storage valve submodule and energy storage system

Abstract

An energy storage valve sub-module and an energy storage system belong to the technical field of power supplies, and comprise an energy storage unit, a power conversion unit, a voltage-sharing resistor assembly and a resistance-capacitance branch which are connected in parallel, the resistance-capacitance branch comprises a first capacitor component and a first resistor component which are connected in series; the energy storage valve sub-module further comprises a second resistor assembly. The second resistor assembly and the first capacitor assembly are connected in parallel and can be in on-off connection; therefore, under the condition that the first resistor assembly fails, for example, the first resistor assembly is disconnected, energy on the first capacitor assembly is released through the second resistor assembly by communicating the second resistor assembly with the first capacitor assembly, and the safety and reliability of the energy storage valve sub-module are improved.

Description

Technical Field

[0001] This application belongs to the technical field of power supplies, and particularly relates to an energy storage valve sub-module and an energy storage system. Background Art

[0002] With the development of large-scale energy storage, energy storage systems have gradually been widely used.

[0003] An energy storage system usually includes a plurality of cascaded energy storage valve sub-modules, and each energy storage valve sub-module includes an energy storage unit. During application, the charge and discharge of the energy storage units in each energy storage valve sub-module can be realized by controlling the switching states of the energy storage valve sub-modules. However, the reliability of such energy storage valve sub-modules is relatively low.

[0004] To solve the reliability problem, a related energy storage valve sub-module is provided with a resistor-capacitor branch connected in series with the energy storage unit. Since this resistor-capacitor branch can suppress the underdamped oscillation current generated when the switching state of the energy storage valve sub-module is switched, the underdamped oscillation current generated when the switching state of the energy storage valve sub-module is switched is greatly reduced, achieving the effect of suppressing the underdamped oscillation current, and greatly reducing the harm brought by the underdamped oscillation current to the energy storage valve sub-module, thereby improving the reliability of the energy storage valve sub-module.

[0005] However, in a related energy storage valve sub-module, the resistor-capacitor branch includes a capacitor component and a resistor component. The capacitor component often cannot release the energy on the capacitor component due to the failure of the resistor component, resulting in poor safety and reliability.

[0006] Therefore, the related energy storage valve sub-module has poor safety and reliability. Utility Model Content

[0007] In view of the above problems, this application provides an energy storage valve sub-module and an energy storage system, aiming to solve the problem of poor safety and reliability of related energy storage valve sub-modules.

[0008] In a first aspect, this application provides an energy storage valve sub-module provided in an embodiment of this application, including an energy storage unit, a power conversion unit, a voltage-sharing resistor component, and a resistor-capacitor branch connected in parallel;

[0009] The resistor-capacitor branch includes a first capacitor component and a first resistor component connected in series;

[0010] The energy storage valve sub-module further includes a second resistor component;

[0011] The second resistor component is connected in parallel with the first capacitor component in a switchable manner.

[0012] In the technical solution of the embodiment of the present application, since the second resistor component is connected in parallel with the first capacitor component and can be connected in a switched-on or -off manner, in the case of the failure of the first resistor component, for example, when the first resistor component is open-circuited, by connecting the second resistor component and the first capacitor component, the energy on the first capacitor component is released through the second resistor component, improving the safety and reliability of the energy storage valve sub-module.

[0013] In some embodiments, the energy storage valve sub-module further includes a first switch;

[0014] The first switch and the second resistor component are connected in series to form a first discharge branch;

[0015] The first discharge branch is connected in parallel with the first capacitor component.

[0016] By adopting the above scheme, the switched-on or -off connection of the second resistor component is realized through the first switch, and the circuit is simple and reliable.

[0017] In some embodiments, it further includes:

[0018] A first sensing circuit, connected to the first capacitor component, configured to detect the voltage across the first capacitor component to output a first sampling signal;

[0019] A first control circuit, connected to the first sensing circuit and the first switch, configured to output a first control signal according to the first sampling signal to control the first switch to close.

[0020] By adopting the above scheme, by detecting the voltage across the first capacitor component to control the first switch to close, the accuracy of the first resistor component fault detection and discharge control is improved.

[0021] In some embodiments, it further includes a second switch;

[0022] The second switch is connected in parallel with the first resistor component.

[0023] By adopting the above scheme, the failed first resistor component can be bypassed by connecting the second switch, so that the energy on the first capacitor component is released through the voltage-sharing resistor component, further improving the safety and reliability of the energy storage valve sub-module.

[0024] In some embodiments, it further includes:

[0025] A second sensing circuit, connected to the first capacitor component, configured to detect the voltage across the first capacitor component to output a second sampling signal;

[0026] A second control circuit, connected to the second sensing circuit, the first switch, and the second switch, is configured to output a second control signal to control the closing of the first switch according to the second sampling signal, and output a third control signal according to the second sampling signal to control the closing of the second switch.

[0027] By adopting the above solution, by detecting the voltage across the first capacitor component to control the closing of the first switch and the second switch, the accuracy of the first resistor component fault detection and discharge control is improved.

[0028] In some embodiments, the energy storage valve sub-module further includes a bypass circuit, and the bypass circuit is connected in parallel with the energy storage valve sub-module.

[0029] By adopting the above solution, by providing a bypass circuit between the ports where the energy storage valve sub-module is connected to the main circuit of the energy storage system, the energy storage valve sub-module can be cut out from the high-voltage direct-connected energy storage system in the case of a fault of the energy storage valve sub-module, improving the operating stability and safety of the energy storage system.

[0030] In some embodiments, the energy storage valve sub-module further includes a buffer capacitor component;

[0031] The buffer capacitor component is connected in parallel with the energy storage unit, the power conversion unit, the voltage equalizing resistor component, and the resistor-capacitor branch.

[0032] By adopting the above solution, by integrally connecting a buffer capacitor component in parallel beside the resistor-capacitor branch, the overvoltage stress at the turn-off moment of the power device in the power conversion unit can be reduced. Thus, the risk of the power device in the power conversion unit failing due to excessive overvoltage stress is reduced, thereby increasing the working reliability of the power device in the power conversion unit and further increasing the working reliability of the energy storage valve sub-module.

[0033] In some embodiments, the power conversion unit includes a first switch tube, a second switch tube, a first diode, and a second diode.

[0034] The input end of the first switch tube and the negative electrode of the first diode together serve as the first positive terminal of the power conversion unit; the output end of the second switch tube and the positive electrode of the second diode together serve as the first negative terminal and the second negative terminal of the power conversion unit; the output end of the first switch tube, the positive electrode of the first diode, the input end of the second switch tube, and the negative electrode of the second diode together serve as the second positive terminal of the power conversion unit.

[0035] By adopting the above solution, the power conversion unit has a simple structure and low cost.

[0036] In some embodiments, the first capacitor component includes a DC support capacitor.

[0037] By adopting the above solution, since the DC support capacitor can support the module voltage or suppress voltage fluctuations, the stability of the output voltage of the energy storage valve sub-module is improved.

[0038] In a second aspect, an embodiment of the present invention further provides an energy storage system, and the energy storage system includes the above-mentioned energy storage valve sub-module.

[0039] The above description is only an overview of the technical solution of the present application. In order to be able to understand the technical means of the present application more clearly, it can be implemented according to the content of the specification. And in order to make the above and other purposes, features and advantages of the present application more obvious and understandable, the following specifically illustrates the specific implementation manners of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] By reading the following detailed description of the preferred embodiments, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present application. And in all the drawings, the same reference numerals are used to represent the same components. In the drawings:

[0041] Figure 1 FIG. is a schematic structural diagram of an energy storage valve sub-module provided by an embodiment of the present application;

[0042] Figure 2 FIG. is another schematic structural diagram of an energy storage valve sub-module provided by an embodiment of the present application;

[0043] Figure 3 FIG. is another schematic structural diagram of an energy storage valve sub-module provided by an embodiment of the present application;

[0044] Figure 4 FIG. is another schematic structural diagram of an energy storage valve sub-module provided by an embodiment of the present application;

[0045] Figure 5 FIG. is another schematic structural diagram of an energy storage valve sub-module provided by an embodiment of the present application;

[0046] Figure 6 FIG. is another schematic structural diagram of an energy storage valve sub-module provided by an embodiment of the present application;

[0047] Figure 7 FIG. is another schematic structural diagram of an energy storage valve sub-module provided by an embodiment of the present application;

[0048] Figure 8 FIG. is another schematic structural diagram of an energy storage valve sub-module provided by an embodiment of the present application;

[0049] Figure 9 Another structural schematic diagram of the energy storage valve sub-module provided by an embodiment of the present application;

[0050] Figure 10 A partial circuit example schematic diagram of the power conversion unit in the energy storage valve sub-module provided by an embodiment of the present application. Detailed implementation manners

[0051] The embodiments of the technical solutions of the present application will be described in detail below with reference to the accompanying drawings. The following embodiments are only used to illustrate the technical solutions of the present application more clearly, so they are only examples and cannot be used to limit the protection scope of the present application.

[0052] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above drawings are intended to cover non-exclusive inclusion.

[0053] In the description of the embodiments of the present application, technical terms such as "first" and "second" are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity, specific order or primary-secondary relationship of the indicated technical features. In the description of the embodiments of the present application, "a plurality of" means more than two, unless otherwise specifically defined.

[0054] Referring to "embodiment" herein means that the specific features, structures or characteristics described in connection with the embodiment may be included in at least one embodiment of the present application. The phrase appears in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art explicitly and implicitly understand that the embodiments described herein may be combined with other embodiments.

[0055] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this article generally represents an "or" relationship between the associated objects before and after.

[0056] In the description of the embodiments of the present application, the term "a plurality of" refers to more than two (including two). Similarly, "a plurality of groups" refers to more than two groups (including two groups), and "a plurality of pieces" refers to more than two pieces (including two pieces).

[0057] Figure 1It is a schematic diagram of an energy storage system architecture, taking the directly-connected energy storage system of three-phase power grid A, B, and C as an example. As Figure 1 shown, the energy storage system includes three-phase energy storage cascaded chains A, B, and C. Each phase of the energy storage cascaded chain includes an arm reactor and m energy storage modules. Among them, the energy storage modules on the three-phase energy storage cascaded chains are respectively represented by SM1#m, SM2#m, and SM3#m, where m is 1, 2, 3,..., n. In other embodiments, such as in a high-voltage DC directly-connected energy storage system, the three-phase alternating current can also be converted into direct current by a converter valve, the energy storage valve is directly connected to the DC power grid, and the energy storage valve includes multiple energy storage valve sub-modules, etc.

[0058] In the related art, the topology of the energy storage valve sub-module in the high-voltage directly-connected energy storage system is as Figure 2 shown, and it includes a resistor-capacitor branch, a power conversion unit, a first capacitor assembly, and an energy storage unit. Among them, Figure 2 S1 and S2 in Figure 1 represent two connection ports. Each energy storage valve sub-module needs to access the main circuit of the high-voltage directly-connected energy storage system through the two connection ports S1 and S2 to be connected to the high-voltage power grid through the main circuit. The connection relationship here can be referred to

[0059] However, this energy storage valve sub-module only adds an underdamped oscillation suppression circuit (resistor-capacitor branch) to reduce the underdamped oscillation current generated when the energy storage valve sub-module switches between on and off states. It cannot release the energy of the capacitor on the resistor-capacitor branch when the resistor in the resistor-capacitor branch fails, resulting in poor safety and reliability.

[0060] In order to solve the problem of releasing the energy of the capacitor in the resistor-capacitor branch when the resistor in the resistor-capacitor branch fails, the applicant's research finds that a switchable resistor assembly can be connected in parallel at both ends of the capacitor in the resistor-capacitor branch. By connecting the resistor assembly when the resistor in the resistor-capacitor branch fails to release the energy of the capacitor in the resistor-capacitor branch, the safety and reliability of the energy storage valve sub-module are improved.

[0061] According to some embodiments of the present application, referring to Figure 3 , Figure 3 shows a schematic structural diagram of an energy storage valve sub-module provided by an embodiment of the present application. For the convenience of description, only the parts related to this embodiment are shown, and the details are as follows:

[0062] The above-mentioned energy storage valve sub-module includes an energy storage unit 10, a power conversion unit 20, a voltage-sharing resistor assembly 30, and a resistor-capacitor branch connected in parallel;

[0063] The resistor-capacitor branch includes a first capacitor assembly 40 and a first resistor assembly 50 connected in series;

[0064] The energy storage valve sub-module further includes a second resistor component 60;

[0065] The second resistor component 60 is connected in parallel with the first capacitor component 40 in a switchable manner.

[0066] It can be understood that the energy storage unit 10 includes one or more cells connected in parallel and / or in series. In the energy storage valve sub-module, the power conversion unit 20 mainly realizes two working modes of the energy storage unit 10 being put into and cut off in the charging and discharging states through different paths. The power conversion unit 20 can be implemented as a half-bridge circuit composed of power semiconductor devices, or a full-bridge circuit composed of power semiconductor devices, or a quasi-full-bridge circuit composed of power semiconductor devices, and so on.

[0067] In the technical solution of the embodiment of the present application, since the second resistor component 60 is connected in parallel with the first capacitor component 40 and can be switched on and off, in the case of failure of the first resistor component 50, for example, in the case of an open circuit of the first resistor component 50, by connecting the second resistor component 60 to the first capacitor component 40, through the discharging action of the second resistor component 60, the energy on the first capacitor component 40 is released, improving the safety and reliability of the energy storage valve sub-module.

[0068] According to some embodiments of the present application, optionally, please continue to refer to Figure 4 , Figure 4 which shows a schematic structural diagram of an energy storage valve sub-module provided by another embodiment of the present application. For the convenience of description, only the parts related to this embodiment are shown and are described in detail as follows:

[0069] In addition to all the components and assemblies of the energy storage valve sub-module as shown in Figure 3 , the energy storage valve sub-module further includes a first switch K1;

[0070] The first switch K1 and the second resistor component 60 are connected in series to form a first discharge branch;

[0071] The first discharge branch is connected in parallel with the first capacitor component 40.

[0072] It should be noted that in the case of failure of the first resistor component 50, the first switch K1 is closed, so that the first discharge branch is turned on, and the second resistor component 60 releases the energy on the first capacitor component 40.

[0073] By adopting the above solution, the switchable connection of the second resistor component 60 is realized through the first switch K1, and the circuit is simple and reliable.

[0074] According to some embodiments of the present application, optionally, please continue to refer to Figure 5 , Figure 5The schematic structural diagram of the energy storage valve sub-module provided by another embodiment of the present application is shown. For the sake of convenience of description, only the parts related to this embodiment are shown and are described in detail as follows:

[0075] In addition to all the components and assemblies of the energy storage valve sub-module as shown in Figure 3 the energy storage valve sub-module further includes a first sensing circuit 70 and a first control circuit 80.

[0076] The first sensing circuit 70 is connected to the first capacitor assembly 40 and is configured to detect the voltage across the first capacitor assembly 40 to output a first sampling signal;

[0077] The first control circuit 80 is connected to the first sensing circuit 70 and the first switch K1 and is configured to output a first control signal according to the first sampling signal to control the closing of the first switch K1.

[0078] It can be understood that the first switch K1 is a normally open switch controlled by the first control circuit 80. The first sensing circuit 70 can be a voltage dividing circuit, and the first control circuit 80 can be a microprocessor or a comparator.

[0079] In one embodiment, the voltage of the first sampling signal is positively correlated with the voltage across the first capacitor assembly 40. The first control circuit 80 is specifically configured to output a first control signal to control the closing of the first switch K1 in response to the voltage of the first sampling signal being greater than or equal to a first preset value after the energy storage valve sub-module is powered off for a preset duration.

[0080] In another embodiment, when the energy storage valve sub-module is powered off, due to the existence of the voltage equalizing resistor assembly 30, the voltage of the first capacitor assembly 40 is the rated working voltage of the energy storage valve sub-module. At this time, the energy of the first capacitor assembly 40 is released through the first resistor assembly 50, the voltage equalizing resistor assembly 30 and the device power supply, and the release time is where U N is the rated operating working voltage of the energy storage valve sub-module, U off is the power-off voltage threshold of the energy harvesting power supply. μ is the efficiency of the energy harvesting power supply, R is the sum of the resistances of the first resistor assembly 50 and the voltage equalizing resistor assembly 30, C is the capacitance value of the first capacitor assembly 40, U C is the voltage of the first capacitor assembly 40, and P is the power of the control board of the energy storage valve sub-module.

[0081] When the voltage of the first capacitor assembly 40 drops to the power-off threshold, the energy of the first capacitor assembly 40 is completely discharged through the resistor assembly (including the first resistor assembly 50 and the voltage equalizing resistor assembly 30). At this time, the voltage drop time of the first capacitor assembly 40 is U o is the capacitance voltage setting threshold of the energy storage valve sub-module.

[0082] By recording the relationship between the voltage and time of the first sampling signal in real time, a first relationship curve is established. Then, the first relationship curve is compared with the formula curve of the voltage drop time of the first capacitor component 40, and a first control signal is output according to the comparison result.

[0083] In another embodiment, after the energy storage valve sub-module is powered off in advance, when the first resistor component 50 with normal configuration function is present, the voltage drop time and voltage value of the first capacitor component 40 can be collected in real time by the first sensor, a preset curve is fitted and stored; then during the operation of the energy storage valve sub-module, the voltage drop time and voltage value of the first capacitor component 40 are collected in real time by the first sensor, a capacitor discharge curve is fitted, and the capacitor discharge curve is compared with the preset curve, and a first control signal is output according to the comparison result.

[0084] By adopting the above scheme, by detecting the voltage across the first capacitor component 40 to control the closing of the first switch K1, the accuracy of the fault detection and discharge control of the first resistor component 50 is improved.

[0085] According to some embodiments of the present application, optionally, please continue to refer to Figure 6 , Figure 6 FIG. shows a schematic structural diagram of an energy storage valve sub-module provided by another embodiment of the present application. For the sake of convenience of description, only the parts related to this embodiment are shown and are described in detail as follows:

[0086] In addition to all the components and assemblies of the energy storage valve sub-module as shown in FIG. 3, the energy storage valve sub-module further includes a second switch K2.

[0087] The second switch K2 is connected in parallel with the first resistor component 50.

[0088] It can be understood that when the first resistor component 50 fails, the second switch K2 closes, so that the discharge loop including the first capacitor component 40, the second switch K2 and the voltage equalizing resistor component 30 is turned on, and the voltage equalizing resistor component 30 releases the energy on the first capacitor component 40.

[0089] By adopting the above scheme, the failed first resistor component 50 can be bypassed by connecting the second switch K2, so that the energy on the first capacitor component 40 is released through the voltage equalizing resistor component 30, further improving the safety and reliability of the energy storage valve sub-module.

[0090] According to some embodiments of the present application, optionally, please continue to refer to Figure 7 , Figure 7The schematic structural diagram of the energy storage valve sub-module provided by another embodiment of the present application is shown. For the sake of convenience of description, only the parts related to this embodiment are shown and are described in detail as follows:

[0091] In addition to all the components and assemblies of the energy storage valve sub-module as shown in Figure 3 the energy storage valve sub-module further includes a second sensing circuit 90 and a second control circuit 100.

[0092] The second sensing circuit 90 is connected to the first capacitor assembly 40 and is configured to detect the voltage across the first capacitor assembly 40 to output a second sampling signal;

[0093] The second control circuit 100 is connected to the second sensing circuit 90, the first switch K1 and the second switch K2, and is configured to output a second control signal to control the closing of the first switch K1 according to the second sampling signal, and output a third control signal according to the second sampling signal to control the closing of the second switch K2.

[0094] It can be understood that at this time, both the first switch K1 and the second switch K2 are normally open switches controlled by the second control circuit 100. The second sensing circuit 90 can be a voltage dividing circuit, and the second control circuit 100 can be a microprocessor or a comparator. In one embodiment, the voltage of the second sampling signal is positively correlated with the voltage across the first capacitor assembly 40. The second control circuit 100 is specifically configured to output the second control signal and the third control signal to control the closing of the first switch K1 and the second switch K2 respectively in response to the voltage of the second sampling signal being greater than or equal to a second preset value after the energy storage valve sub-module is powered off for a preset duration.

[0095] In another embodiment, when the energy storage valve sub-module is powered off, due to the existence of the voltage equalizing resistor assembly 30, the voltage of the first capacitor assembly 40 is the rated operating voltage of the energy storage valve sub-module. At this time, the energy of the first capacitor assembly 40 is released through the first resistor assembly 50, the voltage equalizing resistor assembly 30 and the device power supply, and the release time is where U N is the rated operating voltage of the energy storage valve sub-module, U off is the power-off voltage threshold of the energy harvesting power supply. μ is the efficiency of the energy harvesting power supply, R is the sum of the resistances of the first resistor assembly 50 and the voltage equalizing resistor assembly 30, C is the capacitance value of the first capacitor assembly 40, U C is the voltage of the first capacitor assembly 40, and P is the power of the control board of the energy storage valve sub-module.

[0096] When the voltage of the first capacitor assembly 40 drops to the power-off threshold, the energy of the first capacitor assembly 40 is completely discharged through the resistor assembly (including the first resistor assembly 50 and the voltage equalizing resistor assembly 30). At this time, the voltage drop time of the first capacitor assembly 40 is U o Set a threshold value for the capacitance voltage of the energy storage valve sub-module.

[0097] By recording in real time the relationship between the voltage and time of the first sampling signal, a first relationship curve is established. Then, the first relationship curve is compared with the formula curve of the voltage drop time of the first capacitor assembly 40, and the first control signal and the second control signal are output according to the comparison result.

[0098] In another embodiment, after the energy storage valve sub-module is powered off in advance, when the first resistor assembly 50 with normal configuration function is available, the voltage drop time and voltage value of the first capacitor assembly 40 can be collected in real time by the first sensor, a preset curve is fitted and stored. Then, during the operation of the energy storage valve sub-module, the voltage drop time and voltage value of the first capacitor assembly 40 are collected in real time by the first sensor, a capacitor discharge curve is fitted, and the capacitor discharge curve is compared with the preset curve, and the first control signal and the second control signal are output according to the comparison result.

[0099] By adopting the above solution, by detecting the voltage across the first capacitor assembly 40, the closing of the first switch K1 and the second switch K2 is controlled, improving the accuracy of the fault detection and discharge control of the first resistor assembly 50.

[0100] According to some embodiments of the present application, optionally, please continue to refer to Figure 8 , Figure 8 shows a schematic structural diagram of the energy storage valve sub-module provided by another embodiment of the present application. For the convenience of description, only the parts related to this embodiment are shown, and the details are as follows:

[0101] In addition to all the components and elements of the energy storage valve sub-module as shown in Figure 3 , the energy storage valve sub-module further includes a bypass circuit, and the bypass circuit is connected in parallel with the energy storage valve sub-module.

[0102] In some embodiments, the bypass switch Ks may be, but is not limited to, a mechanical bypass switch Ks or a semiconductor device bypass switch Ks.

[0103] In the case of a fault in the energy storage valve sub-module, the current on the main circuit enters from the S1 port. At this time, the bypass switch Ks closes, and the current flows out from the S2 port through the bypass switch Ks, short-circuiting the entire energy storage valve sub-module and thus completely cutting the energy storage valve sub-module out of the energy storage system.

[0104] By adopting the above solution, by providing a bypass circuit between the ports where the energy storage valve sub-module is connected to the main circuit of the energy storage system, the energy storage valve sub-module can be cut out of the high-voltage direct-connected energy storage system in the case of a fault in the energy storage valve sub-module, improving the operation stability and safety of the energy storage system.

[0105] According to some embodiments of the present application, optionally, please continue to refer to Figure 9 , Figure 9 which shows a schematic structural diagram of an energy storage valve sub-module provided by another embodiment of the present application. For the sake of convenience of description, only the parts related to this embodiment are shown and are described in detail as follows:

[0106] In addition to all the components and assemblies of the energy storage valve sub-module as shown in Figure 3 , the energy storage valve sub-module further includes a buffer capacitor assembly 110;

[0107] The buffer capacitor assembly 110 is connected in parallel with the energy storage unit 10, the power conversion unit 20, the voltage equalizing resistor assembly 30, and the resistor-capacitor branch.

[0108] It can be understood that the function of the buffer capacitor assembly 110 in the energy storage valve sub-module is mainly to buffer the high-frequency current in the current at the moment of input of the energy storage valve sub-module, so as to reduce the rate of change of the turn-off current at the moment when the IGBT is turned off, thereby reducing the overvoltage stress at the moment when the IGBT is turned off.

[0109] By adopting the above scheme, by integrally connecting a buffer capacitor assembly 110 in parallel beside the resistor-capacitor branch, the overvoltage stress at the moment when the power device in the power conversion unit 20 is turned off can be reduced. In this way, the risk that the power device in the power conversion unit 20 fails due to excessive overvoltage stress is reduced, thereby increasing the working reliability of the power device in the power conversion unit 20 and further increasing the working reliability of the energy storage valve sub-module.

[0110] According to some embodiments of the present application, optionally, please continue to refer to Figure 10 , Figure 10 which shows a schematic structural diagram of the power conversion unit 20 in the energy storage valve sub-module provided by another embodiment of the present application. For the sake of convenience of description, only the parts related to this embodiment are shown and are described in detail as follows:

[0111] The power conversion unit 20 includes a first switch K1 tube T1, a second switch K2 tube T2, a first diode D1, and a second diode D2.

[0112] The input end of the first switch K1 tube T1 and the negative electrode of the first diode D1 together serve as the first positive terminal of the power conversion unit 20; the output end of the second switch K2 tube T2 and the positive electrode of the second diode D2 together serve as the first negative terminal and the second negative terminal of the power conversion unit 20; the output end of the first switch K1 tube T1, the positive electrode of the first diode D1, the input end of the second switch K2 tube T2, and the negative electrode of the second diode D2 together serve as the second positive terminal of the power conversion unit 20.

[0113] It should be noted that the above-mentioned switching tubes include triodes, field effect transistors, and insulated gate bipolar transistors.

[0114] Specifically, when the above-mentioned power conversion unit 20 operates in the first switching state: the positive electrode of the first diode D1 is connected to the first direct current output by the power grid, and the negative electrode of the first diode D1 outputs the first direct current to the positive electrode of the energy storage unit 10, and the negative electrode of the energy storage unit 10 outputs the first direct current after charging the energy storage unit 10 to the power grid.

[0115] Specifically, when the above-mentioned power conversion unit 20 operates in the second switching state: the input end of the first switch K1 tube T1 is connected to the second direct current output from the positive electrode of the energy storage unit 10, the output end of the first switch K1 tube T1 outputs the second direct current to the power grid, and the power grid feeds back the second direct current to the negative electrode of the energy storage unit 10.

[0116] Specifically, when the above-mentioned power conversion unit 20 operates in the first cut-off state: the input end of the second switch K2 tube T2 is connected to the first direct current output by the power grid, and the output end of the second switch K2 tube T2 outputs the first direct current.

[0117] Specifically, when the above-mentioned power conversion unit 20 operates in the second cut-off state: the positive electrode of the second diode D2 is connected to the third direct current, and the negative electrode of the second diode D2 outputs the third direct current.

[0118] The structure of the above-mentioned power conversion unit 20 is simple and the cost is relatively low.

[0119] According to some embodiments of the present application, optionally, the first capacitor assembly 40 includes a DC support capacitor.

[0120] It should be noted that the DC support capacitor refers to a capacitor located at the DC end of the module, having a relatively large capacitance value, and is used to support the module voltage or suppress voltage fluctuations.

[0121] By adopting the above solution, since the DC support capacitor can support the module voltage or suppress voltage fluctuations, the stability of the output voltage of the energy storage valve sub-module is improved.

[0122] According to some embodiments of the present application, the present application also provides an energy storage system, including the energy storage valve sub-module of any of the above solutions.

[0123] In specific implementation, the energy storage system may include an energy storage station, and the energy storage valve sub-module stores electrical energy for the energy storage station and releases electrical energy when the power grid is short of energy.

[0124] Since the energy storage system includes the energy storage valve sub-module of any of the above solutions, the energy on the capacitor assembly can be released in the case of the failure of the resistor assembly, improving the safety and reliability of the energy storage valve sub-module.

[0125] It can be understood that the resistor component in the present application can physically be a single resistor or be composed of two or more resistors connected in parallel; the capacitor component can physically be a single capacitor or be composed of two or more capacitors connected in parallel.

[0126] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be covered by the scope of the claims and the description of the present application. In particular, as long as there is no structural conflict, the technical features mentioned in each embodiment can be combined in any way. The present application is not limited to the specific embodiments disclosed in the text, but includes all technical solutions falling within the scope of the claims.

Claims

1. A energy storage valve sub-module, characterized in that, It includes an energy storage unit, a power conversion unit, a voltage equalizing resistor assembly, and an RC branch connected in parallel. The RC branch includes a first capacitor assembly and a first resistor assembly connected in series. The energy storage valve sub-module further includes a second resistor assembly. The second resistor assembly is connected in parallel with the first capacitor assembly and can be connected in a switched-on or -off manner.

2. The energy storage valve sub-module according to claim 1, characterized in that The energy storage valve sub-module further includes a first switch. The first switch and the second resistor assembly are connected in series to form a first discharge branch. The first discharge branch is connected in parallel with the first capacitor assembly.

3. The energy storage valve sub-module according to claim 2, wherein It further includes: A first sensing circuit, connected to the first capacitor assembly, configured to detect the voltage across the first capacitor assembly to output a first sampling signal. A first control circuit, connected to the first sensing circuit and the first switch, configured to output a first control signal according to the first sampling signal to control the closing of the first switch.

4. The energy storage valve sub-module according to claim 1, wherein It further includes a second switch. The second switch is connected in parallel with the first resistor assembly.

5. The energy storage valve sub-module according to claim 4, characterized in that, It further includes: A second sensing circuit, connected to the first capacitor assembly, configured to detect the voltage across the first capacitor assembly to output a second sampling signal. A second control circuit, connected to the second sensing circuit, the first switch, and the second switch, configured to output a second control signal according to the second sampling signal to control the closing of the first switch, and output a third control signal according to the second sampling signal to control the closing of the second switch.

6. The energy storage valve sub-module according to any one of claims 1 to 5, characterized in that The energy storage valve sub-module further includes a bypass circuit, which is connected in parallel with the energy storage valve sub-module.

7. The energy storage valve sub-module according to any one of claims 1 to 5, characterized in that The energy storage valve sub-module further includes a buffer capacitor assembly. The buffer capacitor assembly is connected in parallel with the energy storage unit, the power conversion unit, the voltage equalizing resistor assembly, and the RC branch.

8. The energy storage valve sub-module according to any one of claims 1 to 5, characterized in that, The power conversion unit includes a first switching tube, a second switching tube, a first diode, and a second diode. The input end of the first switching tube and the negative electrode of the first diode together serve as the first positive terminal of the power conversion unit; the output end of the second switching tube and the positive electrode of the second diode together serve as the first negative terminal and the second negative terminal of the power conversion unit; the output end of the first switching tube, the positive electrode of the first diode, the input end of the second switching tube, and the negative electrode of the second diode together serve as the second positive terminal of the power conversion unit.

9. The energy storage valve sub-module according to any one of claims 1 to 5, characterized in that The first capacitor assembly includes a DC support capacitor.

10. An energy storage system, characterized in that, The energy storage system includes the energy storage valve sub-module according to any one of claims 1 to 9.

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